JPH0229808Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to a pressure equalization device that can cope with a wide range of pressure changes inside and outside of a submersible electric motor used under water pressure.

<Prior art> Submersible electric motors used under water pressure have fluid inside them (inside the machine) under pressure, and the pressure of this fluid (internal pressure) and the pressure outside the motor (external pressure) are balanced. Equipped with a pressure equalization device.

Figure 3 shows a typical submersible electric motor equipped with a pressure equalization device. The structure of the electric motor itself is almost the same as a general electric motor, and 1 is the frame of the electric motor, 2 is a shaft supported by the frame 1 via a bearing 3, 4 is a rotor integrated with the shaft 2, and 5 is the side of the frame 1. 6 is a stator coil, and 7 is a cable. A bellows 8 is attached to the case 11 as a bellows pressure equalizing device on one end surface of the frame 1.
It is placed inside. One end of the bellows 8 communicates with the outside of the motor through a hole 15, and the other end communicates with the outside of the motor through a hole 16.
It leads into the electric motor through. The imbalance between the internal pressure and external pressure of the electric motor is corrected by the expansion and contraction of the bellows 8.

<Problems to be solved by the invention> Since the pressure equalization device up to now has only one bellows 8 with a fixed spring constant, if the external pressure becomes higher than expected, The volume of the fluid shrinks and the bellows 8 stretches, making it impossible to adjust the pressure and increasing the pressure difference between the internal pressure of the motor and the external pressure, which may cause water to enter the machine or cause deformation of the frame 1. There is a risk that this may occur. On the other hand, if the volume of the sealed fluid expands due to a rise in temperature during operation of the electric motor, the bellows 8 will be compressed, making it impossible to adjust the pressure and potentially damaging it.

In order to solve the above problems, methods such as increasing the number of bellows to absorb the volume change of the enclosed fluid, increasing the spring constant of the bellows, and even increasing the stroke of the bellows have been considered. However, both have drawbacks such as increasing the overall length of the motor and increasing costs.

In view of the above circumstances, this invention aims to provide a new pressure equalization device that can absorb the pressure difference between the inside and outside of an underwater electric motor over a wide range, without increasing the length of the electric motor, and without increasing the cost. It is something.

<Means for Solving the Problems> In order to solve the above problems, in the present invention, two or more types of bellows with different spring constants are installed in the frame of the submersible electric motor so that one of the inner and outer sides of the bellows is connected to the fluid pressure inside the frame. The other side of the frame was provided to receive fluid pressure from outside the frame.

<Function> Since this pressure equalization device consists of two or more bellows with different spring constants, different bellows function depending on the magnitude of the pressure difference inside and outside the motor.

<Example> FIG. 1 shows an underwater motor equipped with pressure equalizing devices (two in this example) according to an example, and FIG. 2 shows details of the bellows side having a low spring constant.

The configuration of the underwater motor itself is the same as that shown in FIG. Among the brackets 9a and 9b at both ends of the frame 1, which together with the frame 1 constitute a frame body, one bracket 9a is provided with a bellows 10a having a large spring constant, and the other bracket 9b is provided with a bellows 10b having a smaller spring constant than the bellows 10a. will be provided. Both of the bellows 10a and 10b have one side (for example, the outside) facing the fluid inside the electric motor and receiving its pressure, and the other side (for example, the inside) facing water, seawater, etc. outside the electric motor. It's starting to come under pressure.

As shown in FIG. 2, the bellows 10b with a low spring constant is housed in a case 11 integrated with a bracket 9b, one end of which is fixed to the inner end wall surface 12 of the case 11, and a holder 13 attached to the other free end. A guide 14 along the inner surface of the case 11 is attached to the holder 13. A hole 15 is installed in the end wall of the case 11 for introducing external pressure (water pressure) into the bellows 10b. On the other hand, bracket 9b
and the case 11 are communicated through a hole 16, and a stopper 17 on which the holder 13 can abut is provided protruding from the edge of the hole 16.

In the range where the pressure difference inside and outside the motor is relatively small,
The bellows 10b with a smaller spring constant expands and contracts to absorb the pressure difference. When the pressure difference between the inside and outside of the motor becomes large, the bellows 10a having a large spring constant functions to absorb the pressure difference between the inside and outside of the motor. Therefore, the bellows 10a with a larger spring constant is
The spring constant is determined so that the bellows 10a with the smaller spring constant operates within a range where it is not fully extended.
Note that if there is a pressure difference large enough to cause the bellows 10a with a larger spring constant to function, a pressure large enough to fully extend the bellows 10b will act on the bellows 10b with a smaller spring constant.
As shown by the two-dot chain line in Fig. 2, the bellows 10b
Since the holder 13 at the tip hits the stopper 17 on the bracket 9b side and is restrained, the bellows 10b will not be fully extended and damaged.

As described above, by absorbing the pressure difference between the inside and outside of the electric motor using the two types of bellows 10a and 10b with different spring constants, the pressure inside the electric motor is always kept at equilibrium with the outside pressure even if there is a large fluctuation in the pressure difference. This has the effect of being able to maintain the

Note that the two types of bellows 10a, 10b may be provided separately on both brackets 9a, 9b as in the illustrated embodiment, or may be provided separately on one bracket 9a or 9b.
They may be provided together in b. Furthermore, the bellows is 3
Even if more than one is provided, the same effect can be obtained.

<Effects of the invention> The pressure equalization device according to the invention is made up of a combination of multiple types of bellows with different spring constants, so it can respond to a wide range of pressure changes inside and outside the electric motor, and the stroke of each bellows can be short. Therefore, the total length of the electric motor does not need to be increased, and the cost does not increase significantly.

[Brief explanation of the drawing]

Figure 1 is a front view of an underwater electric motor equipped with a pressure equalization device according to the present invention, Figure 2 is a detailed sectional view of the bellows side with a small spring constant, and Figure 3 is a submersible electric motor equipped with a conventional pressure equalization device. FIG. In the drawing, 1 is a frame, 9a and 9b are brackets, 10a is a bellows with a large spring constant, and 10b
1 is a bellows with a small spring constant, 13 is a holder, 1
5 is a hole, and 17 is a stopper.

Claims (1)

[Scope of utility model registration request] An underwater motor characterized in that two or more types of bellows having different spring constants are provided in the frame of the submersible electric motor so that one side of the inside and outside of the bellows receives the fluid pressure inside the frame and the other side receives the pressure outside the frame. Electric motor pressure equalization device.