| Armature shaft for an electrical machine -> Monitor Keywords |
|
|
 
Armature shaft for an electrical machineArmature shaft for an electrical machine description/claimsThe Patent Description & Claims data below is from USPTO Patent Application 20060033401, Armature shaft for an electrical machine. Brief Patent Description - Full Patent Description - Patent Application Claims
BACKGROUND OF THE INVENTION [0001] 1. Field of the Invention [0002] The invention is based on an armature shaft for an electrical machine having a plurality of notches, which extend along the circumference of the armature shaft essentially parallel to the longitudinal direction and form a notching heap. [0003] 2. Description of the Prior Art [0004] In packet-making by means of notches, two notches each extending longitudinally are made in the armature shaft with a two-piece, U-shaped tool. The notching creates a heap or ridge of displaced material, which increases the outer diameter of the armature shaft in the notched region. As a result, the armature shaft can be firmly press-fitted into the bore in the packet. The notching heap joins each lamination in the packet solidly to the armature shaft. Moreover, because the notching heap slightly penetrates the laminations, a positive engagement is achieved which markedly increases the torques of the packet. The axial displacement force of the packet, however, is usually slight, above all at the end laminations, and these laminations must therefore as a rule also be ring-calked. By means of notches, an extremely stable connection is created, which meets the most stringent demands in terms of the quality of the balancing and low-vibration operation. Thus very low-noise motors can be produced. However, complicated technical production prerequisites must be met, if the method is to be used at all with long, thin shafts. [0005] In production, bore tolerances, for instance, selected must be close. The heaps of the notches must likewise have close tolerances; otherwise, the press-fitting forces exceed the buckling force of the shaft. Because of the close tolerances, introducing the shaft is difficult. A high rejection rate must be expected, because of cold welding of shaft material to the packet sheet metal. Especially long packets, with a length of about 50 mm, for instance, have a particularly pronounced tendency to cold welding because of the long press-fitting distances. Because of the relatively high press-fitting forces, excessively great errors of concentricity often occur at the shaft upon press-fitting and must then be corrected manually or by machine in a further operation. Packet-making by press-fitting a notched shaft is indeed the appropriate method for producing low-noise motors that are relatively impact-resistant. However, they require considerable effort and expense technically. Rejections from buckling of the shaft after seizing are highly likely in the press-fitting process. [0006] Notches with a notching heap are in contrast to knurling, in which no notching heaps are created, or only indentations are created because of compaction of the material. This makes knurling unsuitable for an armature shaft to which an armature packet is to be secured. OBJECT AND SUMMARY OF THE INVENTION [0007] The object of the invention is to markedly minimize the high rejection rates in packet-making with a notched, long and thin shaft (for instance, 150 mm long with a 4 mm diameter) and a greater packet length. Moreover, the high structure-borne sound values of small motors, especially small power window motors, are to be reduced markedly. [0008] By means of the armature shaft of the invention for an electrical machine the advantage has been attained that the imbalance of the armature directly after the shafts are press-fitted into the lamination packet is reduced markedly. Moreover, the structure-borne sound of motors is reduced by 8 dBR compared to motors with stamped-out armature packets. For this purpose, an armature shaft for an electrical machine is provided that has a plurality of notches, which extend along the circumference of the armature shaft essentially parallel to its longitudinal direction and form a notching heap; the notches and the notching heaps form acute angles relative to one another. [0009] The acute angle can be formed such that adjacent notching heaps each form an angle of 1.degree. to 5.degree., as a result of which each lamination is securely held. [0010] The acute angle can furthermore be formed by providing that the depth of the notches on one end is greater than on the other end, and that the height of the notching heap on one end is greater than the other end, so that the bottom of the notch and the spine of the notch form the acute angle. The result is a conical course along the shaft, which has a positive effect on the press-fitting process. Preferably, the notch base has a slope of 0.01 mm over 50 mm of length. [0011] The acute angle can also be formed by providing that only the tail ends of the notches are arrowhead-shaped, creating a chamfer on the notching heap that prevents chips from forming in the press-fitting process, because chips in the interstice between the shaft and the notch are the primary cause of seizing. [0012] The armature shaft with the notches can be produced more precisely and in only one operation if the notching heaps extend on only one side of the notches. In this respect it is also advantageous that the notching heaps of adjacent notches are oriented toward or away from one another, which additionally makes easier visual monitoring possible. [0013] Because the notching heaps are rounded, they are not sharp, and thus the tendency to chip development is reduced. [0014] Preferably, the pitch of the notches varies over the circumference in the longitudinal direction, and as a result all the sheet-metal laminations have a defined contact with the armature shaft. This is assured especially well in that a first, second, third and fourth notch are provided; that the first notch and the second notch form an angle with respect to the center axis of the armature shaft, and the angle is smaller than 90.degree. on one end of the notches and larger than 90.degree. on the other end; that the second notch and the third notch form an angle with respect to the center axis of the armature shaft, and the angle is smaller than 90.degree. on one end of the notches and larger than 90.degree. on the other end; that the third notch and the fourth notch form an angle with respect to the center axis of the armature shaft, and the angle is smaller than 90.degree. on one end of the notches and larger than 90.degree. on the other end; and that the larger angle is preferably about 91.degree., and the smaller angle is preferably about 89.degree.. [0015] An armature with an armature packet and with an armature shaft of this kind has only very little imbalance. An electrical machine with such an armature has reduced structure-borne sound. This is advantageous especially in the passenger compartment of a passenger car. BRIEF DESCRIPTION OF THE DRAWINGS [0016] The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of a preferred embodiment, taken in conjunction with the drawings, in which: [0017] FIG. 1 is a side view of an electrical drive unit; [0018] FIG. 2 shows an armature with a partial section; [0019] FIG. 3 shows the armature shaft in an end-on view; [0020] FIG. 4 shows the armature shaft in a developed view; [0021] FIG. 5 shows the armature shaft in a side view; Continue reading about Armature shaft for an electrical machine... Full patent description for Armature shaft for an electrical machine Brief Patent Description - Full Patent Description - Patent Application Claims Click on the above for other options relating to this Armature shaft for an electrical machine patent application. ###  How KEYWORD MONITOR works... a FREE service from FreshPatents1. Sign up (takes 30 seconds). 2. Fill in the keywords to be monitored. 3. Each week you receive an email with patent applications related to your keywords. Start now! - Receive info on patent apps like Armature shaft for an electrical machine or other areas of interest. ### Previous Patent Application: Four-pole synchronous motor Next Patent Application: Transport system and dynamo-electric machine Industry Class: Electrical generator or motor structure ### FreshPatents.com Support Thank you for viewing the Armature shaft for an electrical machine patent info. IP-related news and info Results in 0.1768 seconds Other interesting Feshpatents.com categories: Novartis , Pfizer , Philips , Polaroid , Procter & Gamble , 174 |
 * Protect your Inventions * US Patent Office filing 
PATENT INFO |
|
