GB1588660A

GB1588660A - Electric machines

Info

Publication number: GB1588660A
Application number: GB2061378A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-02-14
Filing date: 1978-05-19
Publication date: 1981-04-29
Also published as: IT7920741V0; FR2417242A7; DE2806116A1

Description

(54) ELECTRIC MACHINES (71) We, ROBERT BOSCH GMBH, a German company of Postfach 50, 7 Stuttgart 1, Federal Republic of Germany. do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to fractional-horsepower electric machines.

An electric motor is already known in which the cover and the housing member are provided with a plurality of mutually associated openings distributed around the periphery, one limb of a U-shaped leaf spring being inserted under tension into each pair of openings. Several working operations are required to produce these bow-type springs. Furthermore, the openings for the U-shaped arms of the leaf springs have to be produced.

The present invention provides a fractional-horsepower electric machine having a tubular housing member in one end portion of which is fitted at least a portion of a cover, said portion of cover being applied against at least one stop shoulder of the housing member by means of at least one spring element, wherein the at least one spring element is arranged so that a portion thereof abuts the side of the, cover remote from the stop shoulder, and an edge of said at least one spring element is in spring engagement with the interior wall of the tubular housing member to maintain the cover in abutment with the stop shoulder.

The , fractional-horspower machine in accordance with the invention has the advantage that the cover is secured to the tubular housing member in a simple manner without having to provide additional fastening shoulders for the spring elements.

Embodiments of the invention are illustrated in the drawings by way of examples, and will be further described in the following description. Figure 1 is a fragmentary longitudinal section through fractionalhorsepower electric motor of a first embodiment, Figure 2 is an elevation of the motor, viewed in the direction of the arrow II of Figure 1; and Figure 3 is a fragmentary elevation, corresponding to Figure 2, of a different embodiment of the motor in accordance with the invention.

A fractional-horsepower motor 10 illustrated in Figure 1 has a tubular housing member 12 of circular cross section, permanent magnets 16 being secured to the interior wall 14 of the housing member.

A motor armature 18 is arranged in the housing member 12 and is secured to an armature shaft 20. The interior space 28 of the housing member is closed by means of a cover 26 which is inserted into that end portion 24 of the tubular housing member 12 which is provided with a mouth 22.

The cover 26 is of cup-shaped construction and is fitted into the end portion 24 of the housing member 12 such that an extension 30 of the cover 26 extends beyond the mouth 22 of the tubular housing member 12. The extension 30 is located coaxially of the inner wall 14 of the tubular housing member 12. The cup-shaped extension 30 merges into a flange-like portion 32 whose diameter is adapted to the diameter of the inner wall 14 of the tubular housing member 12. The concave side of the cupshaped extension 30 is formed to receive a journal bearing 34 in which the armature shaft 20 is carried. Furthermore, the cupshaped extension 30 of the cover 26 has a cylindrical portion 36 which extends substantially at right angles to the flange-like portion 32 of the cover 26. The flangelike portion 32 of the cover 26 abuts against a stop shoulder 38 of the housing member 12, the stop shoulder 38 being formed by a plurality of inwardly pressed tongues 40 which are pressed out of the housing member 12. The tongues 40 are arranged such that the distance from the stop shoulder 38 to the mouth 22 of the tubular housing member 12 is greater than the thickness of the flange-like portion 32 of the cover 26. Thus, an annular chamber 42, open towards the mouth 22 of the tubular housing member 12, is formed between the interior wall 14 of the tubular housing member 12 in the region of the end portion 24 and the cylindrical portion 36 of the cover 26 (Figure 1). The annular chamber 42 accommodates a spring element 44 for securing the cover 26 in its position illustrated in Figure 1. The spring element 44 is of circular construction and has an external diameter which is larger than the internal diameter of the housing member 12. Furthermore, the internal diameter of the circular spring element 44 is smaller than the external diameter of the extension 30 in the region of the cylindrical portion 36 thereof. The outer edge 46 of the spring element 44 is interrupted by a plurality of radially directed, openedged slots 48 (Figure 2). The inner edge 50 of the spring element 44 is sub-divided by a plurality of open-edged radially directed slots 52. The slots 48 in the outer edge 46 are staggered relative to the slots 52 in the inner edge 50. The arrangement of the slots 48 and 52 sub-divide the outer edge 46 and the inner edge 50 of the spring element 44 into a plurality of resiliently deflectable portions 54 and 56.

When the cover 26 is fitted in the housing member 12, the spring element 44 is placed over the extension 30 of the cover 26 and is then pressed into the mouth 22 of the tubular member 12 in the direction of the arrow II. The resilient portions 54 and 56 are then deflected to an extent where the spring element 44 can be pressed into the annular chamber 42 until the spring element 44 comes into abutment against the side of the flange-like. portion 32 of the cover 26, whereupon 32 is located opposite the stop shoulder 38 of the housing portion 12. The sharp knife edges of the outer edge 46 and of the inner edge 50 of the spring element 44 are then clamped against the interior wall 14 of the tubular member 12 and against the cylindrical portion 36 of the cover 26, thus ensuring that the cover is secured in a satisfactory manner. Appropriate tensioning of the portions 54 and 56 also produces an adequate contact pressure by which the cover 26 is applied against the stop shoulder of the housing member 12.

In another embodiment (not illustrated), the internal diameter of the spring element 44 can be chosen to be larger than the external diameter of the cylindrical portion 36 of the cover 26, so that only the outer edge 46 of the spring element 44 is clamped against the interior wall 14 of the housing member 12.

In accordance with the alternative solution illustrated in Figure 3, the spring element 44 is replaced by a plurality of individual leaf springs 60 which are fitted in the annular chamber 42 and whose length is greater than the radial width of the annular chamber 42. Advantageously, the edges of the leaf springs 60, which abut against the interior wall 14 of the tubular housing member 12 and against the cylindrical portion 36, are adapted to the shape of the interior wall 14 of the tubular housing member 12 and the shape of the portion 36. In this case, the leaf springs 60 are separate members which may be removed. However, it is also conceivable for the leaf springs to be shorter than the radial width of the annular chamber 42. In this case, the leaf springs are rigidly connected to the flange-like portion 32 of the cover 26 (by riveting or welding), such that one edge of each leaf spring extends somewhat beyond the rim of the portion 32. Upon fitting the cover 26, these edges are clamped against the interior wall 14 of the tubular housing member 12.

Strictly speaking, the embodiment of Figures 1 and 2 corresponds to the embodiment of Figure 3, although, in the embodiment of Figures 1 and 2, a sufficient number of leaf springs are fitted in the annular chamber 42 to cover the entire annular surface. Furthermore, the individual spring elements separated from one another by the slots 48 and 52 are integrally interconnected in a central annular region.

WHAT WE CLAIM IS: 1. A fractional-horsepower electric machine having a tubular housing member in one end portion of which is fitted at least a portion of a cover, said portion of cover being applied against at least one stop shoulder of the housing member by means of at least one spring element, wherein the at least one spring element is arranged so that a portion thereof abuts the side of the cover remote from the stop shoulder, and an edge of said at least one spring element is in spring engagement with the interior wall of the tubular housing member to maintain the cover in abutment with the stop shoulder.

2. A fractional-horsepower electric machine as claimed in claim 1, wherein the portion of the cover is of flange-like construction and is disposed in a plane located transversely of the axis of the tubular housing member.

3. A fractional-horsepower machine as claimed in claim 1 or 2, wherein the spring element is a leaf spring which is also in spring engagement with the cover.

4. A fractional-horsepower machine as claimed in claim 3, wherein the leaf spring is in spring engagement with an extension of the cover which extends towards the mouth of the tubular housing member.

5. A fractional-horsepower machine as claimed in claim 4, wherein a plurality of leaf springs are fitted into an annular

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. housing member 12 in the region of the end portion 24 and the cylindrical portion 36 of the cover 26 (Figure 1). The annular chamber 42 accommodates a spring element 44 for securing the cover 26 in its position illustrated in Figure 1. The spring element 44 is of circular construction and has an external diameter which is larger than the internal diameter of the housing member 12. Furthermore, the internal diameter of the circular spring element 44 is smaller than the external diameter of the extension 30 in the region of the cylindrical portion 36 thereof. The outer edge 46 of the spring element 44 is interrupted by a plurality of radially directed, openedged slots 48 (Figure 2). The inner edge 50 of the spring element 44 is sub-divided by a plurality of open-edged radially directed slots 52. The slots 48 in the outer edge 46 are staggered relative to the slots 52 in the inner edge 50. The arrangement of the slots 48 and 52 sub-divide the outer edge 46 and the inner edge 50 of the spring element 44 into a plurality of resiliently deflectable portions 54 and 56. When the cover 26 is fitted in the housing member 12, the spring element 44 is placed over the extension 30 of the cover 26 and is then pressed into the mouth 22 of the tubular member 12 in the direction of the arrow II. The resilient portions 54 and 56 are then deflected to an extent where the spring element 44 can be pressed into the annular chamber 42 until the spring element 44 comes into abutment against the side of the flange-like. portion 32 of the cover 26, whereupon 32 is located opposite the stop shoulder 38 of the housing portion 12. The sharp knife edges of the outer edge 46 and of the inner edge 50 of the spring element 44 are then clamped against the interior wall 14 of the tubular member 12 and against the cylindrical portion 36 of the cover 26, thus ensuring that the cover is secured in a satisfactory manner. Appropriate tensioning of the portions 54 and 56 also produces an adequate contact pressure by which the cover 26 is applied against the stop shoulder of the housing member 12. In another embodiment (not illustrated), the internal diameter of the spring element 44 can be chosen to be larger than the external diameter of the cylindrical portion 36 of the cover 26, so that only the outer edge 46 of the spring element 44 is clamped against the interior wall 14 of the housing member 12. In accordance with the alternative solution illustrated in Figure 3, the spring element 44 is replaced by a plurality of individual leaf springs 60 which are fitted in the annular chamber 42 and whose length is greater than the radial width of the annular chamber 42. Advantageously, the edges of the leaf springs 60, which abut against the interior wall 14 of the tubular housing member 12 and against the cylindrical portion 36, are adapted to the shape of the interior wall 14 of the tubular housing member 12 and the shape of the portion 36. In this case, the leaf springs 60 are separate members which may be removed. However, it is also conceivable for the leaf springs to be shorter than the radial width of the annular chamber 42. In this case, the leaf springs are rigidly connected to the flange-like portion 32 of the cover 26 (by riveting or welding), such that one edge of each leaf spring extends somewhat beyond the rim of the portion 32. Upon fitting the cover 26, these edges are clamped against the interior wall 14 of the tubular housing member 12. Strictly speaking, the embodiment of Figures 1 and 2 corresponds to the embodiment of Figure 3, although, in the embodiment of Figures 1 and 2, a sufficient number of leaf springs are fitted in the annular chamber 42 to cover the entire annular surface. Furthermore, the individual spring elements separated from one another by the slots 48 and 52 are integrally interconnected in a central annular region. WHAT WE CLAIM IS:

1. A fractional-horsepower electric machine having a tubular housing member in one end portion of which is fitted at least a portion of a cover, said portion of cover being applied against at least one stop shoulder of the housing member by means of at least one spring element, wherein the at least one spring element is arranged so that a portion thereof abuts the side of the cover remote from the stop shoulder, and an edge of said at least one spring element is in spring engagement with the interior wall of the tubular housing member to maintain the cover in abutment with the stop shoulder.

chamber defined by the interior wall of the tubular housing member and the extension of the cover.

6. A fractional-horsepower machine as claimed in claim 5, wherein the interior wall of the tubular housing member is of cylindrical configuration, and the extension of the cover is located preferably concentrically of the interior wall of the tubular housing member.

7. A fractional-horsepower machine as claimed in claim 6, wherein the leaf springs are interconnected and, in the region of their edges abutting against the interior wall of the tubular housing member and against the extension of the cover, are separated from one another by slots directed preferably towards the axis of the tubular housing member.

8. A fractional-horsepower machine as claimed in claim 7, wherein the leaf springs are in the form of a one-piece annular disc whose external diameter is greater than the internal diameter of the tubular housing member, the outer edge of the annular disc being interrupted by a plurality of, preferably radial, open-ended slots.

9. A fractional-horsepower machine as claimed in claim 8, wherein the internal diameter of the annular disc is smaller than the external diameter of the extension of the cover, and wherein the inner edge of the annular disc is interrupted by a plurality of, preferably radial, open-ended slots.

10. A fractional-horsepower machine as claimed in claim 9, wherein the slots in the inner edge of the disc are staggered relative to the slots in the outer edge.

11. A fractional-horsepower machine as claimed in any of claims 4 to 10, wherein the extension of the cover is open towards the interior space of the tubular housing member and is in the form of means for receiving a bearing element for carrying a machine shaft.

12. A fractional-horsepower machine as claimed in any of claims 1 to 11, wherein the stop shoulder for the cover is formed by preferably a plurality of inwardly pressed tongues which are pressed out of the tubular housing member.

13. Fractional - horsepower e 1 e c t r i c machines substantially as hereinbefore described with reference to the accompanying drawings.