GB2216814A

GB2216814A - Electric motor for food mixer

Info

Publication number: GB2216814A
Application number: GB8806745A
Authority: GB
Inventors: Patrick Shui-Chung Wang
Original assignee: Johnson Electric Industrial Manufactory Ltd
Current assignee: Johnson Electric Industrial Manufactory Ltd
Priority date: 1988-03-22
Filing date: 1988-03-22
Publication date: 1989-10-18
Also published as: GB8806745D0; CN2048638U; DE8903363U1

Abstract

An electric motor for a food mixer has plastics sleeves 11 for holding implements such as beaters, carried in housings 12 cast in the motor frame 2. The sleeves 11 are journalled in drawn steel bearings to avoid the need to ream the housings 12 and to provide greater wear resistance. Adjacent pairs of bearings may be linked by a bridge to prevent rotation of the bearings and provide resistance to lateral spreading of the sleeves 12. The motor comprises a shaft 6 formed with a worm 10 which meshes with wormwheels 13 integral with the sleeves 11. <IMAGE>

Description

ELECTRIC MOTOR The present invention relates to an electric motor, and in particular to a motor having output gears for use in a food mixer or the like.

The present invention provides an electric motor comprising a frame, the frame supporting a stator and brushgear, and having a rotor rotatably mounted therein, the rotor having a shaft with a worm at one end for rotating two wormwheels mounted on the frame, the wormwheels driving respective plastics sleeves which are arranged to receive implements such as food beaters, the sleeves being received in tubular housings formed on the frame, wherein a bearing is provided at each end of each tubular housing, the sleeves being journalled in the bearings.

In prior art arrangements, the plastics sleeve has been journalled directly in the tubular housing which is die cast of alluminium alloy. It is necessary to ream the sleeve to ensure a good fit, and both parts undergo significant wear, limiting the lifetime of the product. By mounting the sleeves in bearings the lifetime is significantly increased and the manufacturing process simplified. The invention is also applicable to motors having frames of other material, such as plastics.

Preferably the bearings at adjacent ends of the housings may be coupled together. This will prevent rotation of the bearings in the housings, and provided increased rigidity between the housings.

Other preferred features and advantages of the invention will be apparent from the following description and the accompanying claims.

The invention will be further described by way of example with reference to the accompanying drawings, in which: Figure 1 is a perspective view of an electric motor in accordance with the invention; and Figure 2 is a schematic cross-section on line II-II of figure 1.

In Figure 1, a universal motor 1 comprises a frame 2 of cast metal, such as aluminium alloy, or moulded from plastics material. The frame 2 supports a U-shaped laminated stator core 3 carrying a stator coil 4, and brushgear 5. A rotor comprising a shaft 6, wound armature coil 7 and commutator 8 is rotatably mounted in bearings 9 carried by the frame 2 (the bearing adjacent the exposed coil end is hidden). The configuration of such universal motors is well known in the art. A worm 18 is formed on an end of the shaft 6. Frame 2 supports two sleeves 11 which are rotatably mounted in tubular housings 12 cast in the frame 1. The lower ends (as seen in the drawings) of the sleeves 11 each have a wormwheel 13 integrally formed thereon, the wormwheels 13 being in mesh with the worm 10.Sleeves 11 each have a through bore 14 and are configured to receive and hold food mixing implements such as beaters. A manner of doing this is well known in the art and need not be described here.

In prior art designs the frame 2 is typically of aluminium alloy and the sleeves are of a hard plastics such as delrin. The housings 12 are reamed to form a sleeve bearing for the sleeves 11. The wear characteristics of such an arrangement are not optimum.

In accordance with the present invention, bearings 15, 16 are inserted in the upper and lower ends of the housings 12. The bearing may be of drawn steel.

This obviates the need to ream the housings 12. Also the frame may be moulded of plastics material.

To prevent rotation of the bearings 15, 16 in the housings 12 they may be an interference fit in the housing ends or keyed to the housings. In a particularly preferred embodiment, the bearings at adjacent housing ends are coupled together by a bridge piece 17 integrally formed with the bearings 15. The bridge piece 17 will prevent rotation of the bearings and also prevent the housings 12 spreading apart at their ends.

In the embodiment shown, the housings 12 are connected at their lower ends by a plate portion 18 of the frame and a bridge 19. Nevertheless, the lower bearings 16 may be connected by a similar bridge piece (not shown).

A flat washer 20 and wavy washer 21 are interposed between the wormwheels 13 and bearings 16, and the sleeves 11 are held in the housings 12 by a circlip 22 and washer 23.

Various modifications may be made to the described embodiment and it is desired to include all such modifications as fall within the scope of the accompanying claims.

Claims

1. An electric motor comprising a frame, the frame supporting a stator and brushgear and having a rotor rotatably mounted therein, the rotor having a shaft with a worm at one end for rotating two wormwheels, the wormwheels driving respective sleeves which are arranged to receive implements such as food beaters, the sleeves being received in tubular housings formed on the frame, wherein a bearing is provided at each end of each tubular housing, the sleeves being journalled in the bearings.

2. An electric motor as claimed in claim 1, wherein the wormwheels are integrally formed on respective sleeves.

3. An electric motor as claimed in claim 1 or 2, wherein the bearing at one end of a housing is connected to the bearing at the adjacent end of the other housing by a bridge piece.

4. An electric motor as claimed in claim 3, wherein the bearings and bridge piece are integrally formed.

5. An electric motor as claimed in any one of claims 1 to 4, wherein the frame is of cast alloy.

6. An electric motor as claimed in any one of claims 1 to 5 wherein the sleeves are of plastics.

7. An electric motor as claimed in any one of claims 1 to 6, wherein the bearings are of drawn steel.

8. An electric motor substantially as hereinbefore described with reference to the accompanying drawings.

9. A food mixer including an electric motor as defined in any one of claims 1 to 8.