Rotor with an oil drain

Abstract

Rotor (1) for a motor, wherein the rotor has a stack of plates, the stack forming a cylindrical body with an axial bore (2) that is rotationally symmetric about a central axis (3) for rotatably supporting the body on an axis, wherein the rotor (1) has a first set of plates forming a first part (12) of the body in which the axial bore (2) has a first diameter, and a second set of plates forming an axially opposite part (11) in which the axial bore (2) has a second diameter which is larger than the first diameter, and each plate is coupled to an adjacent plate by the use of at least one coupling recess (15, 21), wherein the plates of the first set of plates are connected by a first set of coupling pockets (21) at a first radial distance from the central axis (3) and the plates of the second set of plates are connected by a second set of coupling pockets (15) at a second radial distance from the central axis (3), the second distance being greater than the first, wherein the rotor (1) has an oil drain channel (16, 17) which extends through at least part of the body, wherein the oil drain channel (16, 17) is formed at least partially by clutch indentations (21).

Description

Introduction

[0001] The invention relates to a rotor for a motor, the rotor comprising a stack of plates, the stack forming a cylindrical body with an axle bore that is rotationally symmetrical about a central axis for rotationally mounting the body on an axle, the rotor comprising a first set of plates forming a first part in which the axle bore has a first diameter, and a second set of plates forming an axially opposite part in which the axle bore has a second diameter that is larger than the first diameter, and each plate is coupled to an adjacent plate with at least one coupling engagement point.

[0002] The invention further relates to a compressor with a motor having such a rotor, and a method for effecting oil drainage in a compressor. Background of the invention

[0003] Typically, the core of a motor consists of layers of steel plates with several layers of insulators (such as clear varnish) in between. The layered structure prevents eddy currents from heating the core. The multilayer stack is usually formed in progressive dies, meaning the rotor is generally manufactured in a continuous process where: • individual pieces of metal are punched from a steel plate • The steel plates are stacked • the steel plates are connected by domes

[0004] During the coupling process, a small portion of one plate is pressed into a recess or hole in an adjacent plate, forming coupling sinks where the two adjacent plates are joined together. Typically, rotor windings, e.g., in the form of a squirrel cage, are cast into slots in the stacked core, and the layers are thereby firmly fixed by the cast windings—i.e., the sink should only hold the stacked structure until the casting process is complete.

[0005] In electric motors for household applications, such as refrigerators or freezers, etc., the rotor is supported by an axle or shaft through a stepped arrangement. For this purpose, the rotor has a bore with two different radial sizes, i.e., a bore with a stepped configuration that matches that of the axle.

[0006] For example, DE 20 2009 007 597 U1 discloses a rotor core consisting of several layered rotor laminations, which has T-shaped projections for accommodating the winding. The projections also feature embossed portions by which the rotor laminations are connected to the adjacent rotor laminations. The axial bore of the rotor core has regions of different diameters.

[0007] DE 10 2004 011 477 A1 discloses an electric motor with a rotor. Individual lamination sections of such a rotor can be produced by stamping. The laminated lamination sections form a lamination stack of the rotor.

[0008] JP 2002- 354 717 A deals with the provision of a laminated iron core and a manufacturing method therefor.

[0009] Furthermore, a rotor with laminated plate-shaped magnetic elements is known from JP 2007-306 726 A. Due to the stepped design, the clutch recesses are usually positioned at positions that are not optimal with regard to the desired magnetic conductivity of the rotor core. Description of the invention

[0010] It is an object of embodiments of the invention to provide an improved rotor for an electric motor and to provide a method for using improved rotors for oil drainage purposes.

[0011] It is also a task to improve the way the plates in a rotor are connected.

[0012] Accordingly, the invention provides a rotor having the features of claim 1.

[0013] In the rotor, the plates of the first plate set are connected to each other by means of a first set of clutch engagement points at a first radial distance from the center of the axis and the plates of the second plate set are connected by a second set of clutch engagement points at a second radial distance from the center of the axis, the second distance being smaller than the first distance.

[0014] Due to the through-bore with two radial sizes, the magnetic field is different in the first and second parts of the rotor. Since the sinkholes according to the invention are positioned at different radial distances, the sinkholes can be positioned such that they have a smaller negative influence on the magnetic field in both the first and second parts of the rotor. This means that the sinkholes in the first part can be positioned at a distance that best suits the magnetic field in the first part, and the sinkholes of the second part can be positioned at a distance that best suits the magnetic field in the second part.

[0015] Regarding coupling, the following definitions apply throughout this document. Coupling is a process where two adjacent plate-shaped elements are locked together when a sagging point in a first plate is pressed into a recess or opening in the adjacent second plate. The sagging point is generally formed as a protrusion through plastic deformation.

[0016] If we consider a plate 1 in a stack of three adjacent plates, here called plate 0, plate 1, and plate 2, a sag is made in one surface of plate 1, while at the same time plastic deformation makes a depression or opening in the opposite surface of plate 1. The depression or opening in plate 1 can now accommodate a sag from plate 0, and the sag from plate 1 can be accommodated in a depression or opening in plate 2.

[0017] Here, conventional coupling refers to a process where the sagging point is in the form of a bar partially cut out of a plate, such that it forms an open end that is not flush with the plate and the opposite joint side where it connects to the plate. That is, the interface between the flat part of the plate and the externally bonded part is called "the joint" here, and the externally bonded part is called "the bar."

[0018] In general, both the first and second radial distances can be set such that the sag point is as close to the axle bore as mechanically possible. This means that the distance of the sag point from the axle center can depend on the size of the axle bore.

[0019] In particular, it has been found that the second distance may preferably be greater than the first distance since the diameter of the bore in the second part of the rotor body is larger.

[0020] Additionally, the rotor may include plates from an intermediate set of plates arranged between the plates of the first set and the plates of the second set of plates. The plates of the intermediate set of plates are both connected by coupling engagement points of the first set and engagement points of the second set of engagement points. In this way, the first and second parts of the rotor are connected by the plates of the intermediate set of plates.

[0021] The intermediate set of plates may, for example, comprise between 1 and 10 plates, or it may comprise between 5 and 25 percent of the total number of plates in the rotor. The intermediate set of plates may form an intermediate part of the body, which includes pocket locations of both the first and second sets of clutch pocket locations.

[0022] The clutch bagging points of at least one of the first and second groups of bagging points can preferably be Corpack speed bagging points from Corrada (see Corrada company information, URL: http: / / www.eurotranciatura.it / eng / 120_040.php, archived at http: / / www.archive.org on August 24, 2006). In one embodiment, the bagging points of both groups are Corpack speed bagging points, whereas in another embodiment, one group of bagging points can be conventional Corpack bagging points. This could enable the use of the bagging points for oil drainage purposes.

[0023] At least one of the first and second sets of plates can be coupled at a maximum of one coupling insertion point for each plate. In other embodiments, at least one of the first, second, and intermediate sets of plates can be coupled by at least two insertion points for each plate.

[0024] Lubricating oil sometimes enters the engine air gap between the outer surface of the rotor and the inner surface of the stator. This is a disadvantage because it causes wattage surges and reduced system performance due to frictional resistance between the rotor and stator.

[0025] To improve the performance of this type of engine, rotors are sometimes equipped with an oil drain through which the lubricating oil is led in a drainage channel back to the oil pan under the engine.

[0026] The rotor according to the invention has an oil drainage channel extending through at least a part of the body, in particular through the first part of the body in which the axle bore has a smaller diameter.

[0027] The oil drainage channel may, in particular, extend through the axial end of the rotor and the step of the bore. Here, the step of the bore refers to the axial surface that derives from the stepped arrangement of the bore, i.e., the surface that connects the first part of the bore, which has the first diameter, and the part of the bore, which has the second diameter. In this way, oil that penetrates the axle bore can drain from the step through the channel through the first part of the body, where the crankshaft axis fits into the axle bore, thereby preventing oil drainage through this part of the axle bore.

[0028] According to the invention, the oil drain channel is formed at least partially by coupling recesses. In this way, the production of the drain channel can become part of the integrated process of manufacturing, stacking, and coupling the plates.

[0029] To form an oil drainage channel from the sinkholes, it may be advantageous to use conventional coupling principles, whereby a portion of a plate is partially cut out and bent outward away from the surface of the plate.

[0030] In this structure, the holes, although they accommodate the latch of an adjacent plate, remain open for the oil to drain through the plate. In the manufacturing process of the conventional coupling structure, two different processes are performed. In a first process, a round hole is punched out of the plate, and in a subsequent process, the latch is detached from the plate except at the hinge. The latch leaves behind an elongated hole that intersects the first round hole. The resulting hole, at least in principle, is like a keyhole with an elongated arm extending from a circle. Here, we refer to the structure as the "circle and arm" hole.Due to improved drainage capabilities by using the conventional clutch structure, it might be advantageous to use such a structure for at least one of the first and second and intermediate parts of the rotor and to use the opening of these clutch sink points for drainage purposes.

[0031] It may be particularly advantageous to use conventional coupling structures for mounting the first part of the rotor, thereby providing a drainage channel through the first part of the body. In this embodiment, it may be particularly advantageous to prepare the coupling structure so that it is visible at the bore stage. In this embodiment, the plates may be prepared by stamping the aforementioned "circle and arm-shaped" hole in such a way that part of the circle becomes visible at the bore stage, while the arm is hidden under the plates of the first part.

[0032] In general, the drainage channel is preferably hidden under the plates of the first part of the body, so that only an entrance opening into the channel is visible at the drilling stage.

[0033] To increase the stability of the structure, the hinge can preferably be displaced relative to the latch and relative to the hole that accommodates the latch. The displacement of the hinge is in a direction away from the center, i.e., in the direction of a larger radius.

[0034] Due to different radial distances, clutch sinks at one radial distance may form a rotor drainage channel extending through the first part, while other clutch sinks may be at other radial distances, providing better bonding, ie typically at a larger radial distance.

[0035] The clutch recesses forming the drainage channel, or at least part of the channel, can, in particular, be arranged in a helically coiled pattern. This enables improved drainage performance when the rotor rotates in a specific direction relative to the coiled pattern. This can, for example, involve recesses that are rotated in the range of 15-20 degrees, e.g., 16.5 degrees, across 80 to 100 plates.

[0036] In a second aspect, the invention provides a motor, in particular a compressor motor, having a rotor as previously described and as claimed herein.

[0037] Particularly in combination with motors with conical rotors, e.g., in combination with motors with single-sided bearings for the rotor support, i.e., in combination with conventional compressor motors for refrigerators, etc., it is necessary to avoid or at least reduce the presence of oil or coolant in the air gap to reduce frictional resistance on the rotor. This particularly urgent need is caused by the very small air gap typically provided between the rotor and stator in motors of this type.

[0038] In particular, the engine rotor can be adapted to rotate in a direction that matches the helical pattern of the clutch sinkhole, so that the pattern allows oil drainage through the sinkholes as the rotor rotates. This means that when the rotor rotates, e.g., clockwise, the oil or coolant is drawn toward the outside of the channel by centrifugal force and further down into the oil pan, e.g., the bottom of a compressor, by gravity.

[0039] In a third aspect, the invention provides a method of draining oil through a portion of the rotor having a plurality of plates joined together by the use of clutch sinks, the method comprising providing a first set of sinks for use as drain holes for the oil and providing a second set of sinks at different radial distances from the center of the axis of engine rotation. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The invention will now be described by way of example with reference to the following figures, in which: Fig. 1 and Fig. 2 show perspective views of the rotor according to the invention; Fig. Figure 3 shows a cross-section of the rotor according to the invention; Fig. 4 shows a plan view of the rotor; Fig. 5 represents a plate used for the manufacture of the first part of the rotor; Fig. 6 represents a plate used for the manufacture of the intermediate part 13 of the rotor block; Fig. 7 represents a plate used for the manufacture of the second part 11 of the rotor stack; Fig. 8 shows an enlarged view of one of the pocket locations of the first set of pocket locations; and Fig. 9, Fig. 10 represent alternative embodiments of the rotor. DETAILED DESCRIPTION OF AN EMBODIMENT

[0041] Further scope of applicability of the present invention will become apparent from the following detailed descriptions and examples. However, it should be understood that the detailed description and specific examples, which represent preferred embodiments of the invention, are given for illustrative purposes only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description.

[0042] The Fig. The rotor 1 shown in Figures 1-3 is intended for a motor in a refrigerator compressor. The rotor is formed from a stack of plates that form a cylindrical body with an axial bore 2 that is rotationally symmetrical about the central axis 3.

[0043] In the compressor, the rotor is supported by a vertical axis or shaft (not shown). The axis extends from top to bottom through the bore from the upper axial end 4 into the first part 5 of the rotor, see Fig. 3, which represents a cross-section of the rotor. In the first part 5, the bore 2 has a larger diameter.

[0044] The axle extends further into the second part 6, where the bore 2 has a smaller diameter. In this part of the rotor, the axle is typically pressed into the bore, so that the rotor and axle are tightly joined. Due to the interference fit of the axle into the smaller diameter of the axle bore, oil is prevented from flowing between the axle and the inner surface 7 of the bore 2.

[0045] Typically, the axle extends through the lower axial end and forms a cone which is submerged in the oil pan, thereby pumping oil vertically upward into the axle.

[0046] During operation, the oil is pumped upward by the rotation of the shaft and returns to the oil pan under the influence of gravity. In this cycle, oil enters the larger diameter of bore 2.

[0047] Fig. 1 and Fig. 2, lines 9 and 10 illustrate that the rotor has a first portion 12, where the bore has a smaller diameter and where the plates are connected by clutch recesses of the first set and recesses, and a second portion 11 with a corresponding larger diameter in the opposite end of the rotor. The second portion has plates connected by a second set of clutch recesses.

[0048] Between the first and the second part, the rotor has an intermediate part 13 in which the plates are connected by clutch engagement points of the first and second type.

[0049] The slots 14 are for the rotor windings, typically in the form of a squirrel cage cast directly into the slots.

[0050] A clutch pocket 15, namely a clutch pocket of the first set of clutch pocket locations, is visible on the upper axial end 4 of the rotor stack.

[0051] The rotor stack forms two oil drainage channels 16, 17, each of which extends through at least part of the body. The channels 16, 17 begin at the step 18 in the transition between the large and small diameters of the bore 2 and extend to the lower axial end 8.

[0052] Where the channels begin, the entrance is partially hidden under the plates of the first part by the projection 19. To provide improved oil drainage, the plates of the first group may have recesses 20, see also Fig. 5, so that the channels are uncovered. Fig. 10 shows an alternative embodiment in which no recesses are provided in the first part, thus partially concealing the channels.

[0053] The oil drain channels 16,17 are formed by clutch depressions, as will be explained further below.

[0054] Fig. Figure 4 shows a top view of the rotor. In this view, the partially concealed inlet openings 20 into the channels 16, 17 are clearly visible.

[0055] Fig. Figure 5 shows a plate used for manufacturing the first part 12 of the rotor stack. The plates are assembled with, for example, a single clutch pocket, e.g., a Speedy Corepack type, or with any number and type of clutch pocket.

[0056] Fig. Figure 6 shows a plate used to manufacture the intermediate section 13 of the rotor stack. The plates are assembled, for example, with a double set of sagging points, e.g., a Speedy Corepack Type 15 and a standard Corepack sagging point 21, which forms a hole 22 in the plate. This hole 22 forms one of the aforementioned channels 16, 17.

[0057] Fig. Figure 7 shows a plate used for manufacturing the second part 11 of the rotor block. The plates are joined together, e.g., with a single indentation or a set of indentations 21, e.g., of the conventional Corpack type, so that the holes 22 form the channels 16, 17.

[0058] Fig. Figure 8 shows an enlarged view of the pocket locations 21 of the first set of pocket locations and one of the pocket locations 15 of the second set of pocket locations. The pocket location 21 includes a latch 24 connected to the plate 25 by a hinge 26. The hinge is displaced radially outward relative to the latch and relative to the hole that receives the latch. In practice, the hinge is simply a portion of the plate that is bent outward, away from the plane of the plate.

[0059] Fig. 9, Fig.10 represent the above-mentioned embodiment, where the inputs to the channels 16,17 are partially covered.

Claims

[1] A rotor (1) for a motor, the rotor comprising a stack of plates, the stack forming a cylindrical body with an axle bore (2) which is rotationally symmetrical about a central axis (3) for rotatably supporting the body on an axis, the rotor (1) comprising a first set of plates forming a first part (12) of the body in which the axle bore (2) has a first diameter, and a second set of plates forming an axially opposite part (11) in which the axle bore (2) has a second diameter which is larger than the first diameter, and each plate is coupled to an adjacent plate by the use of at least one coupling pocket (15, 21), wherein the plates of the first set of plates are connected by a first set of coupling engagement points (21) at a first radial distance from the central axis (3) and the plates of the second set of plates are connected by a second set of coupling engagement points (15) at a second radial distance from the central axis (3), the second distance being greater than the first, wherein the rotor (1) has an oil drain channel (16, 17) extending through at least part of the body, wherein the oil drain channel (16, 17) is at least partially formed by clutch sink points (21). [2] A rotor according to claim 1, wherein an intermediate set of plates (13) are connected by both coupling pocket locations (21) of the first set and pocket locations (15) of the second set of pocket locations. [3] A rotor according to any one of the preceding claims, wherein the clutch pocket locations (15, 21) of at least one of the first and second sets of pocket locations are conventional clutch pocket locations. [4] A rotor according to any one of the preceding claims, wherein at least a first set of plates are connected by at most one clutch engagement point for each plate. [5] A rotor according to any one of the preceding claims, wherein at least a second set of plates is connected by at least two clutch engagement points for each plate. [6] A rotor according to any one of the preceding claims, wherein the second set of clutch sink points forms a helically wound pattern in the first part of the body, the helically wound pattern. [7] A rotor according to any one of the preceding claims, wherein the drain channel is hidden beneath the plates of the second part (11) and has an inlet opening into the channel located at the junction (18) of the bore between the first and second parts of the rotor. [8] A rotor according to any one of the preceding claims, wherein at least one of the first and second sets of pocket locations comprises a latch (24) connected to the plate (25) with a hinge (26), the hinge being displaced radially outwardly relative to the latch and relative to the hole in which the latch is received. [9] A motor comprising a rotor according to any one of the preceding claims. [10] An engine according to claim 9, wherein a rotor is adapted for rotation in a rotational direction and wherein the second set of clutch pockets forms a helically coiled pattern having a coiling direction that facilitates the drainage of oil through the pockets of the second set of clutch pockets when the rotor rotates in the rotational direction. [11] A compressor comprising a motor according to claim 9 or 10.

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