JPS58192454A - Cooler for brush of rotary electric machine - Google Patents

Abstract

PURPOSE:To facilitate the maintenance of a brush for a rotary electric machine and to improve the mechanical strength of the brush by burying a heat pipe in the main wall of a brush retainer. CONSTITUTION:A heat pipe 13 is buried in the main wall 5c of a brush retainer 5. In other words, a hole of small diameter is formed between the ends of the head of the main wall 5c at the side of a current collecting ring 1, and the pipe 13 is buried in the hole. An evaporation unit T of the pipe 13 is provided at the head side with a condenser S at the end of the evaporation unit T of the pipe 13 at the side of the ring 3. The pipe 13 may be held with the wall 5c instead of burying the pipe 13 in the wall 5c.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling device for a bluff for a rotating electrical machine, and more particularly to a cooling device for a bluff for a rotating electrical machine having a heat pipe.

As is well known, except for special cases such as oil cooling or water cooling,
The cooling method used to cool the brushes and current collecting ring of the current collector is to cool the brushes and current collecting ring by forcing ventilation by a fan installed externally or on the rotor itself. It is normal to have However, as the capacity of rotating electric machines has increased in recent years and the field current has increased, the number of brushes attached to the same current collection ring has also increased, and the density of brush attachment (installation density) has increased. At the same time, the current flowing through the brush also increases. Such an increase in brush mounting density and brush current density increases the resistance loss caused by frictional heat and current due to sliding contact between the brush and the current collector ring, and reduces the temperature near the contact area between the brush and the current collector ring. raise it abnormally. This temperature rise causes the brushes to lose their lubricating action, causing increased brush wear and chatter, leading to increased brush breakage and current collector ring damage, which does not seriously impede the operation of the rotating electrical machine. It becomes like this.

Therefore, in large-capacity rotating electric machines, forced ventilation is used to provide sufficient cooling air to the current collector to suppress temperature rises, but as the capacity of rotating electric machines increases, the number of brush holes installed increases. Then, since the brush and the plank holder are arranged so as to cover the outer peripheral surface of the current collecting ring, the amount of air flowing through the surface of the current collecting ring is limited. For this reason, effective cooling cannot be obtained simply by increasing the air volume and speed using the forced ventilation method, and a phenomenon that inhibits sliding contact of the brushes tends to occur.

A conventional example of such brush cooling is shown in FIG. The figure takes the case of a turbine generator as an example, and the current collector ring (rotating current collector) 1 is attached to the rotor shaft 2 via an insulator 3. Brushes 4 are attached to the outer peripheral surface at approximately equal intervals. This plan 4 is supported by a plan holder 5 so as to be in sliding contact with the current collecting ring 1, and its head is pressed with a predetermined pressure by a spring 6 provided in the plan holder 5. The brush retainer 5 is fixed to a bus ring 7 which carries out current transmission to a generator field (not shown). In the current collector configured in this way, plan 4 is the rotor shaft 2
Forced draft cooling is performed by a cooling fan 8 installed coaxially with the cooling fan 8 .

In other words, as shown by the arrow in the figure, the cooling fan 8
The cooling air taken in from the intake port a is Plan 4,
After cooling the plan holder 5, the current collecting ring 1, and the internal hole 9 of the current collecting ring 1, it enters the ventilation path partitioned by the guides 10 and 11 and is discharged from the exhaust port 1]. In the figure, 12 is a cover for the entire current collector.

In the bra/4 and plan holder 5 which are cooled by ventilation in this way, the current collecting ring 1 as shown in FIG.
A, A near the sliding contact surface side.

The temperature distribution with respect to the radial length A-E of the blade/rabra/4 and the radial length A, ~F1 of the brush holder 5 changes as shown in FIG. 3.

In Figure 3, the vertical axis shows the temperature, and the horizontal axis shows the temperature according to the radial length by taking the respective radial lengths mentioned above. .

Temperature curve 1) Plan holder temperature curve Q shown as a one-dot line
As shown in , the temperature of both the brush and the brush holder is high near the sliding contact surface, and the temperature decreases as the distance from A, A near the sliding contact surface in the radial direction increases. There is.

That is, as shown by the curve P, from the OA near the sliding contact surface of the brush to the brush box 5a (see FIG. 2)
The temperature gradient dT/dL (T is the temperature, L is the length of the plan) from the brush box end C to the vicinity of the plan box end C (near the brush head) is It is extremely small compared to the anus in Et. This is because, compared to the A-0 section on the sliding contact surface side, the C-E section on the radial end side is exposed from the brush box, so heat dissipation due to ventilation is greater. In addition, the temperature curve Q according to the length of the brush retainer almost corresponds to the plan temperature curve P, and there are two points in the figure for Fl near the radial end side (plano retainer, near the head of the retainer). It is approximately equal to the internal temperature S shown by the chain line. The brush box usually has a space of 0.1 to 0.0 mm between the brush and the brush so that the brush can move freely.
Since there is a gap of 5 degrees, the thermal resistance of (5)/1 degree between the brush and the plan holder is large, but there is still a gap of about 80 degrees between the brush and the brush holder, which is the source of heat. % of heat is transferred. This is because the material of the brush holder is made of a good thermal conductor. In this way, the vicinity of the brush head, which is the vicinity of the radial end E of the brush, receives a good flow of cooling air, so cooling is extremely good, but the temperature rise is excessive in the vicinity of the sliding contact surface with the current collector ring. , the plan is unable to maintain normal sliding contact and begins to chatter.

As a measure to reduce the temperature near this plano sliding contact surface, it is possible to improve the temperature to some extent by installing brushes that can easily receive the flow of cooling air, that is, by increasing the distance between adjacent plans. It is possible. This increases the outer circumferential surface area of the current collection ring, and cooling air can easily circulate by increasing the diameter of the current collection ring or increasing the width (length in the axial direction) of the current collection ring. Brushes can be attached at brush intervals. However, increasing the diameter of the current collection ring increases the circumferential speed of the brush sliding part.
(6) This makes the sliding contact of the brushes unstable, and increasing the width of the current collector ring increases the axial length of the rotating electric machine, which is not desirable.

An alternative to this is a cooling method using heat pipes that utilizes evaporation of refrigerant and latent heat. This is done by attaching one end of the heat pipe to a part of the brush box near the brush sliding contact surface, which is the source of the bluff temperature rise, and using it as a heating evaporation section, and cooling the other end as a heat dissipation condensation section. It is something. As is well known, the operating performance of this heat pipe is determined by the cooling capacity of the heat radiating part, so there are two methods: exposing the heat radiating part to the outside through the cover of the current collector and cooling it naturally, and cooling the area around the current collecting ring. One possible method is to provide a heat dissipation section in the cooling air passageway for forced cooling. According to these methods, the temperature near the sliding contact surface of the brush is reduced and the change in temperature due to the radial length of the brush is suppressed, as shown by the temperature curve R shown by the dashed line in Fig. 3. However, in the former case, when used as a current collector for a large-capacity rotating electric machine, the distance to the cover is long, resulting in a long heat pipe and an unstable structure.

In addition, in the latter case, the heat dissipation parts of the heat nozzles stand in a row near the brush holder and protrude, so maintenance operations such as brush replacement and inspection are extremely difficult to perform on rotating electric machines where multiple planar blades are installed. There are some serious drawbacks.

The present invention has been made in view of the above points, and an object thereof is to provide a cooling device for brushes for a rotating electrical machine that is mechanically strong and easy to maintain.

That is, the present invention is characterized in that the heat pipe is embedded in the main wall of the plan holder.

The present invention will be explained below based on the illustrated embodiments. $
FIG. 4 shows an embodiment of the present invention. Note that parts that are the same as those in the conventional model are given the same reference numerals, and therefore their explanations will be omitted. In this embodiment, the end pipe 13 is connected to the main wall 5 of the brush holder 5.
It was buried in C. That is, a small diameter hole was provided between the head of the main wall 5C and the side end of the current collecting ring 1, and the heat tube 13 was buried in this small diameter hole. The evaporating section T of the heat pipe 13 was provided at the end on the current collecting ring 3 side, and the condensing section S was provided on the head side. By doing so, it is possible to obtain a cooling device for brushes for a rotating electrical machine that is mechanically strong and easy to maintain. That is, the heat pipe 13 is connected to the main wall 5C.
Since it is wrapped by the main wall 5C, it does not become elongated and lack stability against vibrations etc. as in the conventional case, and the mechanical strength is improved and it becomes stable. In addition, since the heat pipes 13 are placed inside the existing main wall 5C, the heat pipes 13 will not stand in a forest or protrude from the vicinity of the brush holder 5 due to mud, and there will be no obstructions.
Maintenance such as replacement and inspection work becomes easier.

Of course, the heat generated between the brush 4 and the current collector ring 1 is released into the atmosphere from the evaporation section T through the condensation section S, as indicated by the arrow in the figure, and a good cooling effect can be achieved. Needless to say.

In this embodiment, the heat pipe 13 is buried in the main wall 5c, but it may be buried in the main wall 5C. In this case as well, the same effects as described in (9) above can be achieved.

Another embodiment of the invention is shown in FIG.

In this embodiment, the heat pipe 13a was formed with its evaporation portion T in contact with the brush 4. In this way, the heat generated from the brush 4 can be directly conducted to the heat vibrator 13a, so that the cooling effect of the plan 4 can be made better than in the case described above.

FIG. 6 shows yet another embodiment of the invention. In this embodiment, a plurality of heat pipes 13b are provided with their evaporation parts in contact with the plan 4. By doing so, the amount of heat directly conducted from the plastic/4 to the heat pipe 13b increases, and the cooling effect of the brush 4 can be improved more than in the case described above.

Further embodiments of the present invention are shown in FIGS. 7 and 8. In this embodiment, a part of the heat pipe 13C is made to protrude from the main wall 5C, and a cooling fin 14 is provided on the protrusion to form a condensing section S.

By doing this, the condensing part S is
) Since the brush 4 is exposed to cooling air, heat dissipation is improved, and the cooling effect of the brush 4 can be improved compared to the case described above. Note that since the heat squib 13C has its condensing portion S only partially protruding from the head 5b of the plan holder 5, there is no concern that the mechanical strength will be impaired.

As described above, in the present invention, the heat pipe is embedded in the main wall of the existing brush holder, so that it is wrapped in the main wall, and the heat pipe becomes long or close to the brush holder as in the conventional case. The beat pipes do not stand in a row or protrude, and a mechanically strong brush cooling device for a rotating electrical machine that is easy to maintain and that is mechanically strong can be obtained.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional side view of a current collector of a conventional brush cooling device for rotating electric machines, Fig. 2 is a longitudinal cross-sectional side view of the brushes and brush holder of a conventional brush cooling device for rotating electric machines, and Fig. 3 is a vertical cross-sectional side view of a current collector of a conventional brush cooling device for rotating electric machines. FIG. 4 is a characteristic diagram showing the relationship between the radial length and temperature of the brushes and brush holder of a cooling device for a conventional rotating electric machine plan. FIG. 5 is a vertical side view of another embodiment of the brush cooling device for rotating electrical machines of the present invention, and FIG. 6 is a longitudinal sectional side view of another embodiment of the brush cooling device for rotating electrical machines of the present invention. FIG. 7 is a longitudinal sectional side view of a current collector of still another embodiment of the brush cooling device for a rotating electric machine of the present invention, and FIG. 8 is a longitudinal sectional side view of a cooling device of still another embodiment of the present invention. Out. ■... Current collector ring (rotating current collector), 4... Plan, 5...
...Brush retainer, 5C...Main wall, 13, 13a, 1
3b. 13G... Heat pipe, S... Condensing section, T...
Evaporation section. Agent: Patent attorney Hiroo Nagasaki (and 1 other person)” (12) Figure 4 Figure 5 Dream 7 l

Claims (1)

[Scope of Claims] 1. A rotating electric machine brush cooling device that cools brushes held by a brush holder and sliding on the surface of a rotating current collector using cooling air and a heat pipe, wherein the heat pipe A brush cooling device for a rotating electric machine, characterized in that the brush holder is embedded in the main wall of the brush holder. 2. The cooling device for a brush for a rotating electric machine according to claim 1, wherein the heat pipe is formed with an evaporation portion thereof in contact with the brush. 3. The cooling device for a brush for a rotating electric machine according to claim 1, wherein the heat pipe is a plurality of heat pipes each having an evaporation portion that is in contact with the brush.