JPS6155333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to electrically conductive brushes for rotating electrical machines, and more particularly to apparatus for supporting and manipulating brushes proximate a current collection ring of a rotating electrical machine.

Recently, as the power ratings of rotating electrical machines have increased significantly, properly handling the large amounts of heat generated in the machine's current-carrying conductors has become a significant problem. Due to the very large dimensions of certain parts, and the consequent difficulty in assembling and transporting certain unit parts, it has been decided not to increase the size of certain parts of the machine any further. The problem of avoiding overheating is particularly important as higher ratings become desirable.

One component of a machine that requires increased current carrying capacity is the current collector assembly, where it is desired to increase the rating without increasing the length or diameter of the rotor of the rotating electrical machine. This section typically uses brushes of conductive material, such as graphite, to carry current from the stationary parts of the machine to a rotating collector ring, which provides magnetizing power to the rotor's field windings. . Excessive heat generated in this area can cause the temperature of the brushes to rise to high levels, causing rapid wear and tear on the brushes, requiring their frequent replacement, and causing damage to the current collection ring. It may cause damage.

In the prior art, there are several devices for attaching brushes to rotating electrical machines, such as those described in U.S. Pat. No. 3,387,155, U.S. Pat. Other brush assemblies are disclosed in US Pat. Nos. 3,628,051, 3,968,391 and US Pat.
Described in No. 3983432. Both of the patents mentioned above describe devices by which brushes can be removed from a current collector ring or other rotating parts of a rotating electrical machine without stopping the operation of the machine. Further, both patents describe a box-shaped structure that houses and supports the brushes so that they rest stably on the current collection ring.

While such conventional devices can reduce the labor involved in replacing worn brushes and avoid power outages and wasted time associated with stopping and restarting the rotor of a machine, in certain applications However, the box-like structure that these devices create around the brushes can prevent heat from being carried away from the brushes. This box-shaped structure acts to shield most of the brush from the surrounding gas, usually air. JS Bischop et al.'s paper ``Large Turbine Power Generation'' presented at the Joint Power Conference of the Institute of Electrical and Electronics Engineers and the American Society of Mechanical Engineers in September 1974. Some machines, such as turbine generators with excitation systems such as those described in ``Attempts at Alterex Excitation for Machines'', use fans to circulate air near the brushes and current collector rings. However, especially at higher ratings, this arrangement may not be as efficient as it would like, since the fan must overcome the shielding effects of the brush box. As a result, too much power may be consumed to pump the air, or the brushes may operate at high temperatures and wear out quickly. Frequent inspection and replacement of the 100 or more brushes on a typical large rotating electrical machine is a significant maintenance expense.

It is therefore an object of the present invention to support a conductive brush near the rotor of a rotating electrical machine such that substantially all lateral areas of the brush are exposed and do not impede the carrying away of heat from the brush. and to provide an improved apparatus for operating the same.

Another object of the present invention is to provide a brush holder apparatus with internally supported brushes to improve heat transfer from the face of the brush and to reduce wear and tear on the brush.

Another object of the invention is to include a retainer that properly directs the cooling gas near the brushes and that allows worn brushes to be safely removed and replaced without having to take the rotating electrical machine out of service. Another object of the present invention is to provide a brush holder device that also includes means for.

The present invention provides an apparatus for supporting and operating a conductive brush near the rotor of a rotating electrical machine. In a preferred embodiment of the invention, the brush holder assembly has a pair of generally parallel pins or legs which fit into the longitudinal holes of the brush and which are connected to the current collecting ring of the rotating electrical machine. It supports the brush when it is worn, thus leaving substantially all of the outer surface of the brush exposed so that heat can be carried away from the brush. In a preferred embodiment, a cylindrical casing concentric with the rotor provides support for the brush holder assembly. The brush holder assembly projects inwardly through an opening in the casing toward the current collection ring. The casing provides a ventilation envelope that properly directs the cooling gas circulated by the fan, as well as a common electrical connection between the several brush holder assemblies and the current source. A removable insulating handle allows the brush holder assembly to be removed and inserted without stopping the operation of the rotating electrical machine. During these operations, the brush retention lever ensures that the brush is retained by the brush holder assembly.

Although the gist of the invention is specifically and clearly described in the claims, the invention will be better understood from the following description of the drawings.

FIG. 1 depicts a portion of a rotating electrical machine representing a typical operating environment for a preferred embodiment of the invention. In the illustrated configuration, a rotor 30 having a field winding 31 is arranged to rotate within a laminated stator core 32, which is surrounded by an airtight main housing 34. The rotor 30 extends past the main housing 34 and is located inside the current collector assembly 36. The main action of the current collector assembly is
The purpose of this is to convey current from an excitation source (not shown) to the rotating field winding 31. Current collector assembly 3
6 is a current collecting ring 3 attached to the outer periphery of the rotor 30;
8, a plurality of conductive brushes 40 are supported by a brush holder assembly 42 near or in contact with the current collection ring 38. The current collector assembly may include a fan, such as radial fan 43 mounted on the rotor 30, to circulate a cooling gas, such as air, near the brushes 40 and current collection ring 38. As is known in the art, the current collector ring 38 connects the field winding 31 of the rotor of the rotating electrical machine by means such as radially extending terminal bolts 44 and generally axially disposed connecting rods 46. electrically connected to. Both the bolt 44 and the connecting rod 46 have an insulating ring 47
It is suitably insulated from the rotor 30 by.
It goes without saying that a typical rotating electric machine has another current collector assembly on the opposite side of the fan 43 to provide a return path for the current flowing from the field winding 31 to the excitation source (not shown). Nor. Each brush row shown in FIG. 1 typically has several brushes spaced apart along the collector ring 38, with the number of brush rows depending on the current rating of the collector, the size of the brushes, and the brush size. related to other factors.

In a preferred configuration of the invention shown in FIG.
A stationary conductor or busbar ring that provides a common electrical connection between the brush holder assembly 42 and the excitation source is preferably cylindrical and connected to the rotor 30.
It is constituted by a concentric casing 48 of. The casing 48 firmly supports the brush holder assembly 42 and is circulated by a fan 43 to provide high gas velocity and heat transfer near the brush 40 and current collector ring 38. This provides a flow path for the cooling gas.

The preferred embodiment of the brush holder assembly 42, shown in more detail in FIGS. 2, 3 and 4, has a pair of generally parallel elongated members or cylindrical brush pins 50 which are connected to the block. 52 and is firmly attached to the block 52 using a pin 54 or the like. The lower part of the brush pin 50 can be slidably inserted into a mating vertical hole 55 provided in the brush 40 to stably support the brush when it rests on the current collector ring 38. Brush pin 50 supports brush 40 from the inside, unlike conventional devices which are box-shaped and supported externally, so that the sides of the brush (typically four sides of a rectangular shape) are close to the brush. It remains freely exposed to the circulating cooling gas, thus significantly improving convective heat transfer.

The brush holding lever 56 may be a channel member (a member having a channel or U-shaped cross section), but may be attached to the brush holder assembly 42 by a pivot pin 58 or the like.
a first position in which the lever 56 is pivotally connected to the block 52 of the brush holder assembly 42 so that the lever does not contact the brush 40 supported on the brush holder assembly 42; Casing 4
8 and a second position (shown in phantom in FIG. 2) that allows the brush 40 to be retained by the brush holder assembly 42 during insertion or removal from the appropriate hole 60 in FIG. (by means to be explained later). coil spring 6
2 can be attached to the free end of lever 56 by rivets 64 or the like. As is known in the art, this spring applies a force pressing the brush 40 against the current collector ring 38 to account for changes in the height of the brush 40 due to wear and tear.

As shown in FIGS. 2, 3, and 4, the lower body member 68 is mounted and firmly attached to the head of the block 52 of the brush holder assembly 42 by a pair of countersunk screws 66 or the like. There is. The lower body member 68 is attached to the upper body member 7 by a pair of screws 72.
Attached to 0. Screws 72 attach cap 73 to upper body member 70. Lower body member 68 may have a pair of locating pins 74 that can be inserted into mating holes (not shown) in casing 48. The positioning pin 74 is
This helps orient the brush holder assembly 42 when inserting it into the casing 48.

The block 52 also has means such as a threaded hole 75 and a bolt 76 for engaging the brush 4.
A flexible conductor or pair of conductors 77 from 0
is attached to the brush holder assembly 42, and the brush 4 is attached to the brush holder assembly 42.
0 and the brush holder assembly 42.

In the upper portion of the brush holder assembly 42 is a rotatable rod 78. The rod has a cylindrical portion that passes through an opening 79 in cap 73 (see FIGS. 2 and 5) and a hole 80 in upper body member 70, and a cylindrical portion that is smaller in diameter and extends through hole 82 in lower body member 68. and a lower cylindrical portion extending therethrough and into hole 84 in block 52. The lower portion of rod 78 has a cam portion 86 which abuts one end of a pin 88 located in a recess 90 in block 52. Since the other end of the pin 88 contacts the side surface of the brush holding lever 56, the rod 7
As the cam portion 86 of
position, the lever 56 is rotated to a second position in which the lower end of the lever 56 engages the side of the brush 40. block 52
A spring 94 disposed in the hole 96 contacts the side of the lever 56 below the pivot pin 58, and the pin 88 and the lever 56
6 is maintained in contact with brush 40, and when rod 78 returns to its initial position, it applies a return moment that returns lever 56 to its first position out of contact with brush 40.

The portion of the rod 78 that passes through the lower body member 68 is covered with a plurality of Belleville washers 97.
The washers abut a collar on the rod 78 formed at the intersection between the upper and lower cylindrical portions of the rod 78 to attach the brush holder assembly 42 to the casing 48. Alternatively, the rod 78 may be allowed to flex slightly in the axial direction when removed from there.

A locking pin 98 extends from the upper portion of rod 78 and passes through a pair of slots 100 on opposite sides of upper body member 70 . Each slot 100 is generally in the shape of a right triangle when viewed from above (see FIG. 4), and the rod 78
When the fixing pin 98 is turned, the fixing pin 98 can be rotated within a limited range. A top view of the brush holder assembly 42 mounted within the opening 60 of the casing 48 is shown in FIG.
FIG. 6 is a side view showing the relationship between the fixing pin 98 and the pair of protrusions 101. A pair of protrusions 101 are attached to the shoulders (not shown) of the casing 48 within the opening 60 by bolts 102, 103, etc.
is installed. The protrusion 101 is connected to the fixing pin 9
8 and thus secure the brush holder assembly 42 to the casing 48.

A removable handle 104 is provided to facilitate insertion and removal of the brush holder assembly 42 and associated brush 40 into the casing 48.
is provided. At least the upper portion of the handle 104 is insulated from the brush holder assembly 42 so that worn brushes can be inspected and replaced without risk of electrical shock during operation of the rotating electrical machine. In the embodiment shown in FIGS. 3 and 4, the handle 104 is connected to the upper shaft 105 and the transverse member 106, both of which are made of non-metallic or non-conductive material, and the upper shaft 108 by means of a pin 108 or the like.
The lower shaft 107 held inside the lower shaft 1
07 and a transparent protection disk 110 attached to it. The lower shaft 107 has a hole 112 below the shielding disc 110 that slidably receives a spring 114 and a washer 116. Handle 10
4 is not in contact with assembly 42, spring 114
and washer 116 is connected to hole 1 by horizontal pin 118.
12. The transverse pin 118 is inserted into the recess 12 of the rotatable rod 78 of the brush holder assembly 42.
0, and as shown in FIG.
When 8 is pressed down, the notch 122 of the cap 73
(See Figure 5) The dimensions are such that it can be passed through.

Because of the casing 48, unless the brush holder assembly 42 is removed from the casing 48,
Since it is difficult to visually inspect brushes for wear directly, each brush is provided with a wear indicator or scale 124.
(see FIG. 2), and the access port (opening through which the wear indicator passes) 12 is attached to the main body members 68, 70.
6 is preferably provided so that the wear indicator 124 passes through the brush holder assembly 42 and is visible from the outside of the casing 48.

Next, the operation of the device of this invention will be explained. To remove brush holder assembly 42 and brush 40 from casing 48, handle 104 is inserted into recess 120 in rotatable rod 78 of brush holder assembly 42, and the head of rod 78 and washer 1 of handle 104 are removed.
16 applies downward pressure to rod 78. This compresses the spring 114 and washer 97, allowing the transverse pin 118 to pass through the notch 122 in the cap 73. Next, when the handle 104 is rotated approximately 45 degrees, this rotation is stopped by the contact between the fixing pin 98 and the side surface of the slot 100 of the upper body member 70. Handle 104
By the rotation of the rod 78, the horizontal pin 118 is pressed under the cap 73, and the horizontal pin 118 is pressed against the spring 1.
14 and washer 97, it is firmly pressed against the cap. Therefore, the handle 104 and the brush holder assembly 42 are fixed. By turning the aforementioned handle 104, the fixing pin 9
8 disengages from protrusion 101, thereby releasing brush holder assembly 42 from casing 48 and moving brush holding lever 56 into firm contact with brush 40. At this point, handle 104, brush holder assembly 42, and brush 40 can be lifted from casing 48 as a unit. Next, if desired, rotate the handle 104 in the opposite direction to the brush 40.
can be removed from the brush holder assembly 42. With a new brush in place, the brush holder assembly 42 and brush can be installed in the operative position by reversing the steps described above.

As described above, it is possible to easily dissipate heat from the brushes and current collecting ring of a rotating electrical machine, and also to easily perform maintenance work on the brushes while the machine is operating.
An apparatus has been described that includes a brush holder assembly, a casing, and a removable handle. The preferred configuration of the apparatus described above has been tested and found to reduce the maximum average brush operating temperature by about a factor of four and to extend the useful life of the brush by about a factor of two.

While the preferred embodiments of the invention have been illustrated and described, it will be appreciated that various modifications may be made thereto. For example, although the device has been described with respect to individual brushes or a single brush, U.S. Pat.
It is also easy to apply the invention to interlocking or magazine type brush holder devices such as those described in No. 3,387,155. Additionally, knowing the invention, other means of mounting the brush in an enclosed or semi-enclosed area with substantially all sides exposed so as to provide effective heat transfer will be readily apparent to those skilled in the art. I can think of it. It is understood that all such modifications are included within the scope of this invention.

[Brief explanation of the drawing]

FIG. 1 is a side view of a portion of a rotating electrical machine, partially cut away to show the interior, showing a current collector assembly and several brush holder assemblies mounted in a casing in accordance with the invention; , the brush holder assembly supports the brushes near the current collector ring of the machine. FIG. 2 shows the brush holder assembly of the present invention and the brush holder assembly supported therein.
FIG. 3 is a side view of the brush disposed near the current collector ring, with the brush retaining lever positioned to engage the side of the brush also shown in broken lines. Figure 3 is a front view of the brush holder assembly, associated brushes, and removable insulating handle used to insert and remove the assembly and brushes from the casing; Figure 4 is a front view of the brush holder assembly and associated brushes; FIG. 3 is a perspective view of the associated brush, with the removable handle removed; FIG. 5 is a plan view of the brush holder assembly seen through the opening in the casing, and FIG. 6 is a side view showing the relationship between the fixing pin and the pair of protrusions, showing a preferred method of attachment to the casing that supports the assembly. Explanation of main symbols, 30: rotor, 38: current collector ring, 40: brush, 42: brush holder assembly, 43: fan, 48: casing, 50: brush pin, 56: brush holding lever, 60: Opening, 62: Coil spring, 78: Rotatable rod, 9
8: Fixing pin, 101: Projection, 104: Detachable handle, 124: Wear indicator.

Claims (1)

[Scope of Claims] 1. An apparatus for supporting and operating an electrically conductive brush that facilitates the exchange of current between the electrically conductive brush and a current collecting ring of a rotor of a rotating electrical machine, comprising: having a pair of elongated members inserted into the longitudinal holes of the brush so that the brush is slidably held and substantially all sides of the brush are exposed so that heat is carried away by the cooling gas near the brush; a brush holder assembly disposed concentrically with and radially outwardly of the current collector ring for removably retaining the brush holder assembly in position; Apparatus including a casing having an open end for directing a flow of cooling gas between the casing and the casing past the surface of the brush. 2. The apparatus according to claim 1, wherein the brush holder assembly is inserted into or removed from the casing and into a first position in which the brush holder assembly is pivotally attached to the assembly and the lever does not come into contact with the brush. Apparatus having a brush retaining lever rotatable between a second position abutting and engaging the brush for retaining the brush in the brush assembly. 3. The apparatus according to claim 2, further comprising means for fixing the brush holder assembly to the casing, the means being attached to the brush holder assembly, and the brush holder assembly being attached to the casing. a rod rotatable between a first position fixed to the casing and a second position where the brush holder assembly can be inserted into or removed from the casing; and a rod extending substantially perpendicularly to the axis of the rod. A device having a removable fixing pin and a protrusion further attached to the casing and defining a recess for receiving the fixing pin when the rod is rotated to the first position. 4. The device according to claim 3, further comprising a brush wear indicator attached to the brush, movable together with the brush, and having a scale graduated with a distance indicating wear of the brush. 5. The apparatus according to claim 2, wherein the brush holder assembly is arranged to operate between the brush holding lever and the brush and pushes the brush into contact with the current collecting ring. A device containing a spring that attaches. 6. The apparatus according to claim 1, wherein a fan is attached to the rotor of a rotating electric machine, and the apparatus has a gas inlet connected to one end of a cylindrical casing having an open end, and has a brush and a current collector. A device that circulates cooling gas near the ring.