JP3417593B2 - Attaching method of sheathed heater to stator of rotating electric machine - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a sheathed heater for heating air, which is installed inside a rotating electric machine. 2. Description of the Related Art For example, in an electric motor for explosion-proof or outdoor use, a sheath heater for heating air is installed inside the electric motor in order to prevent dew condensation on a stator winding. FIG.
FIG. 5 to FIG. 5 show a method of mounting a conventional sheathed heater. In FIG. 3, reference numeral 1 denotes an outer frame, which is a ring-shaped frame 2.
And brackets 3 and 4 fitted and fixed to both ends of the frame 2. Reference numeral 5 denotes a stator core fitted and fixed to the inner peripheral surface of the frame 2 and wound with a stator winding 6. Reference numeral 7 denotes the frame 2 positioned beside the axial end of the stator winding 6. A shaft heater rotatably supported by the brackets 3, 4; and 9, a rotor fitted and fixed to the outer peripheral surface of the shaft 8. The sheath heater 7 is specifically mounted as shown in FIGS. First, a plurality of screw holes are formed in the inner peripheral surface of the frame 2 located beside the axial end of the stator winding 6, and a C-shaped sheathed heater 7 is inserted at this position. . Next, the sheath heater 7 is hooked and supported on the sheath heater support portion 10 of the plurality of mounting brackets 12 including the sheath heater supporting portion 10 and the fixing portion 11 having screw holes, and the fixing portion 11 of the mounting bracket 12 is framed. 2 and is fastened and fixed to the frame 2 by the fastening screw 13. However, the prior art has the following problems. (1) The entire surface of the fixing portion 11 of the mounting bracket 12 is
A part of the heat generated by the sheath heater 7 flows to the frame 2 through the mounting bracket 12 and is wastefully radiated to the outside air, so that the inside air of the motor Temperature does not rise efficiently. (2) When the capacity of the sheathed heater is increased in order to increase the inside air temperature of the motor, the surface temperature of the sheathed heater 7 away from the mounting bracket increases accordingly, exceeding the allowable temperature value specified as the explosion-proof motor. There is a risk that it will. (3) Since a plurality of mounting brackets 12 are used, the operation of mounting the sheathed heater 7 is troublesome. The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a method of mounting a sheathed heater capable of efficiently increasing the inside air temperature of an electric motor. [0004] In order to solve the above-mentioned problems, a method for mounting a sheathed heater according to the present invention comprises a ring-shaped frame and an outer frame comprising a bracket fitted and fixed to the frame. A stator fitted to the inner peripheral surface of the frame and having a stator core wound with a stator winding, the stator supporting a C-shaped sheathed heater, and at least intermittently. A ring-shaped mounting bracket with a plurality of screw holes formed in a cylindrical fixed part,
The stator winding is inserted into the outer frame located beside the axial end of the stator winding, and a mounting screw is screwed into the screw hole from the inside. The mounting bracket is mounted on the outer frame by pressing against the surface. [0005] By the above means, the contact area between the mounting bracket and the outer frame becomes very small, and the heat of the sheath heater hardly flows to the outer frame side. An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a side sectional view showing a mounting portion of a sheath heater, and FIG. 2 is a front sectional view. The mounting of the sheath heater 7 to the frame 2 is performed as follows. First, the mounting bracket 14 does not use a plurality of small ones, but uses one formed in a ring shape. The mounting bracket 14 has, for example, an L-shaped cross section, and includes a cylindrical fixing portion 15 and a flange-shaped sheath heater support portion 16. Screw holes (not shown) are formed at a plurality of positions in the cylindrical fixing portion 15. The C-shaped sheet heater 7 is attached to the sheet heater support 1 of the mounting bracket 14.
After being fixed to the frame 6 by the mounting piece 17, it is inserted into the frame 2 and positioned beside the axial end of the stator winding 6. Next, the mounting screw 18 is screwed into the screw hole of the fixing portion 15 of the mounting bracket 14 from the inside, and the tip of the mounting screw 18 is pressed against the inner peripheral surface of the frame 2. By doing so, the mounting bracket 14 is firmly attached to the frame 2 by the reaction force against the frame 2. In the operation of mounting the sheathed heater, the sheathed heater 7 and the mounting screw 18 are attached to the mounting bracket 14 in advance to make the unit separate, thereby facilitating the operation. In such a sheath heater mounting method, since the mounting bracket 14 does not come into contact with the frame 2 and only the tip end of the mounting screw 18 comes into contact with the frame 2, the contact area between the two is very small. Heater 7
Hardly flows into the frame 2. Therefore, the inside air temperature of the electric motor can be efficiently increased. Further, since screw holes are not formed in the frame 2 and screws are not tightened in the screw holes, the axial setting position of the sheathed heater 7 on the frame 2 is free, positioning is simplified, and the mounting position is reduced. It can be changed freely. Furthermore, since the surface of the mounting bracket 14 does not contact the inner peripheral surface of the frame 2 at the position where the sheathed heater 7 is attached, the dimensional tolerance accuracy and surface roughness accuracy of the inner peripheral surface of the frame 2 can be roughened. If a V-shaped or U-shaped groove is formed in the inner circumferential surface of the frame 2 at the position where the sheathed heater 7 is attached, it is possible to prevent the sheathed heater 7 from being displaced in the axial direction for some reason. it can. In the above embodiment, the frame 2
Although an example in which the sheathed heater 7 is attached to the motor is shown, the sheathed heater 7 may be attached to the inner peripheral surface of the bracket 3 in an electric motor having a structure in which the frame 2 is short and the bracket 3 is long. That is, the sheathed heater 7 may be attached to either the frame or the bracket constituting the outer frame. Further, the mounting bracket 14 may be formed in a ring shape only at the fixed portion 15, and the sheathed heater support portion 16 may be formed intermittently only at the portion to which the mounting piece 17 is attached, or conversely, the sheathed heater support portion 1.
6 is a ring shape, and the fixing portion 15 is a mounting screw 18.
May be formed only intermittently. Further, an intermediate portion between the fixing portion 15 and the sheathed heater support portion 16 is formed in a ring shape, and the fixed portion 15 and the sheathed heater support portion 16 are intermittently provided only at a portion where the mounting screw 18 is mounted and a portion where the mounting piece 17 is mounted. It may be formed. Furthermore, the mounting bracket 14 may be constituted only by a fixing portion 15 formed in a ring shape, and the sheath heater 7 may be fixed to the fixing portion 15 by a mounting piece 17. As described above, the present invention has the following effects. (1) The contact area between the mounting bracket and the outer frame becomes very small, and the heat of the sheath heater hardly flows to the outer frame side, so that the inside air temperature of the electric motor can be raised efficiently. (2) Processing and assembly work for mounting the sheathed heater is simplified.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side sectional view showing a mounting portion of a sheathed heater according to an embodiment of the present invention. FIG. 2 is a front sectional view showing a mounting portion of a sheathed heater according to the embodiment of the present invention. FIG. 3 is a side view showing a motor in a conventional example, and shows an upper half in a cross section. FIG. 4 is a side sectional view showing a mounting portion of a sheathed heater in a conventional example. FIG. 5 is a front sectional view showing a mounting portion of a sheathed heater in a conventional example. [Description of Signs] 1 Outer frame 2 Frame 3, 4 Bracket 5 Stator core 6 Stator winding 7 Sheath heater 8 Shaft 9 Rotor 14 Mounting bracket 15 Cylindrical fixing part 16 Sheath heater support part 17 Mounting piece 18 Mounting screw

Continuation of the front page (56) References JP-A-60-245446 (JP, A) JP-A-58-43165 (JP, U) JP-A-60-51770 (JP, U) JP-A-57-45275 (JP) , U) Fully open sho 60-77262 (JP, U) Fully open sho 60-99866 (JP, U) Fully open sho 61-14878 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB Name) H02K 11/00 H05B 3/02-3/18 H05B 3/40-3/82

Claims (1)

(57) [Claim 1] A ring-shaped frame, an outer frame composed of a bracket fitted and fixed to the frame, and a stator fitted and fixed to an inner peripheral surface of the frame. A stator for a rotary electric machine having a stator core wound with windings, supporting a C-shaped sheathed heater, and forming a plurality of screw holes in at least an intermittently formed cylindrical fixed portion. The ring-shaped mounting bracket is inserted into the outer frame located beside the axial end of the stator winding, and the mounting screw is screwed into the screw hole from the inside. A mounting portion mounted on the outer frame by pressing a portion against an inner peripheral surface of the outer frame.