Double-casing frame of an electric machine

Abstract

Disclosed is a double-casing frame of an electric machine that is cooled by a fluid circulating in the fluid circulation space (26) inside the double casing, said double-casing frame comprising: an inner casing (22) on which an end flange (30) is mounted at the rear of the machine; and an outer casing (24) that fits over the inner casing (22) and can be separated from the inner casing (22) without removing the end flange (30).

Claims

1. A double-casing frame of an electric machine which is cooled by a fluid circulating inside the double casing, comprising: an inner casing; an end flange mounted on the inner casing at a rear; and an outer casing which fits over a front of the inner casing and is separable from the inner casing without removing the end flange by sliding the outer casing to the rear along the inner casing, the outer casing and the inner casing defining between them a fluid circulation space, the outer casing having a rear end wall oriented perpendicularly to an axis of rotation of the electric machine and at least partially covering the inner casing, the outer casing forming with the end flange a radial clearance e.

2. The frame as claimed in claim 1, the inner casing having a rear end wall oriented perpendicularly to an axis of the rotation of the electrical machine and covering the end flange over a part of its height, the end flange being mounted on the rear end wall of the inner casing.

3. The frame as claimed in claim 1, the outer casing being removably fixed to the inner casing and/or to the end flange.

4. The frame as claimed in claim 1, the radial clearance being between 0.5 mm and 5 mm.

5. The frame as claimed in claim 1, the end flange not having any elements for fixing to the outer casing.

6. The frame as claimed in claim 1, the outer casing at least partially covering the end flange.

7. The frame as claimed in claim 1, the outer casing covering the inner casing over only a part of its length.

8. The frame as claimed in claim 7, the inner casing and the outer casing being made of stainless steel.

9. The frame as claimed in claim 1, the inner casing comprising a front assembly flange, a front end wall of the outer casing being fixed thereto.

10. The frame as claimed in claim 1, the inner casing comprising a passage for cables toward a terminal box of the electrical machine, the terminal box being mounted thereon, and the passage for cables being in front of the outer casing.

11. The frame as claimed in claim 1, the outer casing comprising a terminal box support, the terminal box of the electrical machine being removably fixed thereto.

12. The frame as claimed in claim 1, an external surface of the inner casing and/or an internal surface of the outer casing having ribs forming chicanes in the fluid circulation space.

13. The frame as claimed in claim 12, the ribs being longitudinal.

14. The frame as claimed in claim 1, comprising a seal between a rear end wall of the inner casing and the rear end wall of the outer casing.

15. The frame as claimed in claim 1, comprising at least one headless screw borne by one of the inner casings and the outer casing comprising a drilled hole into which this screw may be engaged.

16. The frame as claimed in claim 1, the inner casing and/or the outer casing comprising lifting lugs for the frame.

17. The frame as claimed in claim 1, the outer casing comprising an orifice for an inlet of fluid into the fluid circulation space and an orifice for an outlet of fluid from the fluid circulation space.

18. A double-casing electric machine which is cooled by a fluid circulating inside the double casing, comprising a frame, as claimed in claim 1.

19. The double-casing electric machine as claimed in claim 18, comprising a terminal box which is fixed to the inner casing.

20. The double-casing electric machine as claimed in claim 19, the outer casing being separable from the inner casing without removing the terminal box from the inner casing.

21. The double-casing electric machine as claimed in claim 19, the terminal box being removably fixed to the outer casing.

22. A method for inspecting the fluid circulation space of a frame of an electric machine, as claimed in claim 1, comprising the steps consisting in unscrewing bolts for fixing the outer casing to the inner casing and then removing the outer casing and inspecting the fluid circulation space in order to check an absence of undesirable elements.

Description

(1) The invention will be understood more clearly by reading the following detailed description of the non-limiting exemplary embodiments thereof, and by examining the accompanying drawing, in which:

(2) FIG. 1 shows schematically in section an electric motor according to the invention,

(3) FIG. 2 shows the inner casing of the frame illustrated in FIG. 1,

(4) FIG. 3 is a schematic view in section of the assembled inner and outer casings of the frame illustrated in FIG. 1,

(5) FIG. 4 is an enlarged view of the end of the motor of FIG. 1,

(6) FIG. 5 shows schematically the electric machine according to the invention,

(7) FIG. 6 is a schematic view in section of a detail of the electric machine according to the invention illustrating the separation of the casings,

(8) FIG. 7 shows schematically the assembly of a terminal box on an electric machine according to the invention,

(9) FIG. 8 shows schematically the separation of the inner and outer casings of an electric machine according to the invention, and

(10) FIG. 9 shows a variant of the frame according to the invention.

(11) The electric machine 10 shown in FIGS. 1 to 8 is a motor comprising a frame 20 of elongated shape, along a longitudinal axis X, which is closed at its two axial ends by front and rear flanges 30.

(12) The frame 20 surrounds a stator 13, the rotor 11 rotating therein.

(13) The rotor 11 comprises a shaft 15, having a longitudinal axis X, which is guided by bearings 32 borne by the flanges 30 in the conventional manner. The rotor may also comprise fan blades 17 at the front and rear, at its front and rear ends.

(14) The flanges 30 each have a grease nipple 34 to supply the bearings 32 with lubricant.

(15) The frame 20 comprises an inner casing 22 nested in an outer casing 24. The inner casing 22 and the outer casing 24 form together a fluid circulation space 26 extending over the entire circumference of the electric motor 10.

(16) In FIGS. 5 to 8, the outer casing 24 is shown transparently for illustrative purposes.

(17) The circulation of fluid in this space 26 is guided by longitudinal ribs 28.

(18) As visible in FIG. 2, these longitudinal ribs 28 protrude over the external surface of the inner casing 22.

(19) In a variant, not illustrated, the ribs 28 extend from the internal surface of the outer casing 24, or extend from the external surface of the inner casing 22 and from the internal surface of the outer casing 24.

(20) The ribs 28 are distributed equally around the longitudinal axis and extend alternately as far as one or the other of the walls forming the front 45 and rear 38 assembly flanges, axially delimiting the space 26, so as to form chicanes to force the fluid to follow a zigzag path.

(21) The ribs 28 are of uniform section over their entire length.

(22) The frame 20 may comprise between 6 and 16 ribs 28.

(23) The distance d edge to edge between two consecutive ribs 28 is between 6 cm and 30 cm.

(24) The outer casing 24 comprises openings for the inlet of fluid 55 into the circulation space 26 and openings for the outlet of fluid 57 therefrom.

(25) The angular position of the outer casing 24 is set relative to the inner casing using a headless screw 70 which is screwed into a tapped portion 72 of the inner casing 22 and engaged in a corresponding hole of the outer casing 24.

(26) The outer casing 24 comprises a front end wall 46 which is fixed to the front assembly flange 45 of the inner casing 22 by bolts 48. One at least of the front end wall 46 and the front assembly flange 45 comprises, as illustrated in FIGS. 1 and 3, an annular groove 50 receiving an O-ring, not shown. Such a seal makes it possible to ensure the sealing of the fluid circulation space 26 on the side of the front end of the electric motor 10.

(27) As illustrated in FIGS. 4 and 6, the outer casing 24 comprises the rear wall 38 forming an assembly flange which is fixed to a rear end wall 40 of the inner casing 22 by bolts 42.

(28) The rear end wall 40 may comprise, as illustrated in FIGS. 1 and 4, an annular groove 44 which is arranged opposite the rear end wall 38 of the outer casing 24 and receives an O-ring, not shown. Such a seal makes it possible to ensure the sealing of the assembly between the casings on the side of the rear end of the electric motor 10.

(29) The rear flange 30 of the motor 10 comes into contact with the rear end wall 40 of the inner casing 22 and is fixed to the rear end wall 40 of the inner casing 22 by bolts 43.

(30) The rear end wall 38 of the outer casing 24 is superposed at least partially radially on the rear flange 30, forming therewith a radial clearance e, for example of between 0.5 mm and 5 mm, for example substantially equal to 2 mm. The rear flange 30 and the rear end wall 38 of the outer casing 24 are not superposed.

(31) The outer casing 24 axially covers the inner casing 22 over a length l which is less than that L of the inner casing 22. Thus a part of the inner casing 22 is exposed relative to the outer casing 24 so as to be able to bear, in particular, a terminal box 54 without the removal thereof being necessary for the separation of the inner casing 22 and the outer casing 24.

(32) In this part of the inner casing, which is not covered by the outer casing 24, the inner casing 22 has a passage for cables 52 toward a terminal box 54. The passage for cables 52 comprises an assembly flange 53 of the terminal box 54, the terminal box 54 being fixed thereto by bolts 56 as is shown in FIGS. 1, 5, 7 and 8.

(33) In the illustrated example, the terminal box 54 extends to the rear of the motor in the extension of the part of the frame 20 in which the two casings 22 and 24 are superposed.

(34) As illustrated in FIG. 7, the outer casing 24 may comprise a support 62 of the terminal box 54, a U-shaped bracket 75 being fixed thereto for fixing the terminal box 54 to the support 54. The arms of the U-shaped bracket 75 are fixed to the lateral walls of the support 62 by bolts 77 and the base of the U-shaped bracket 75 is fixed to the terminal box 54 by bolts 80. It is thus possible to remove the bolts 77 in a simple manner so as to detach the U-shaped bracket 75 in a simple manner from the outer casing 24 without having to separate it from the terminal box 54. Thus it is not necessary to remove the terminal box 54 in order to separate the two casings 22 and 24.

(35) The casings 22 and 24 have lifting lugs 60.

(36) The two casings 22 and 24 may be produced by machining a single cylindrical tube made of stainless steel, the inner casing being produced in a first portion of the tube and the outer casing in a second portion of the tube located in the extension of the first portion. However, this may be carried out differently.

(37) In order to inspect the fluid circulation space 26, as illustrated in FIGS. 6 and 8, the user may empty the fluid circulation space 26 by evacuating the fluid via the fluid outlet orifice 57, unscrew the bolts 42, 48 and 77 in order to detach the outer casing 24 from the inner casing 22 and from the U-shaped bracket 75, slide the outer casing 24 to the rear on the inner casing 22 so as to open up the space 26 between the two casings.

(38) Once the inspection is finished, the user may easily reassemble the frame by carrying out the reverse procedure.

(39) The user thus does not have to remove the rear flange 30 or the terminal box 54 in order to carry out the inspection.

(40) In the variant illustrated in FIG. 9, the rear end wall 38 of the outer casing 24 extends to the rear of the inner casing 22 and of the rear flange 30. The rear end wall may be fixed by a bolted connection to the rear flange 30. The rear end wall is thus able to slide to the rear without being prevented from doing so by the rear flange, which prevents it being necessary to remove said rear flange in order to inspect the fluid circulation space 26.