JPH06253504A - Fixing method of sheath heater in stator for electric rotating machine - Google Patents

Abstract

PURPOSE:To allow efficient temperature rise of the air in a motor by decreasing the contact area between the fixing metal and the outer frame. CONSTITUTION:An annular fixing metal 14 having a plurality of screw holes is inserted into the outer frame, located closely to the axial end part of a fixed winding, of a fixing part 15 formed in cylindrical shape at least intermittently and supporting a C-shaped sheath heater 7. At the same time, a fixing screw 18 is pressed, at the tip thereof, against the inner peripheral surface of the outer frame thus fixing the fixing metal 14 to the outer frame. This constitution reduces the contact area between the fixing metal and the outer frame significantly to scarcely transmit heat from the sheath heater 7 to the outer frame side thus raising the inner air temperature of a motor efficiently.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of mounting a sheath heater for heating air, which is installed inside a rotary electric machine.

[0002]

2. Description of the Related Art For example, in an explosion-proof or outdoor electric motor, a sheath heater for heating air is installed inside the electric motor in order to prevent dew condensation on the stator winding. Figure 3
5 to 5 show a conventional method for attaching a sheathed heater. In FIG. 3, 1 is 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 that is fitted and fixed to the inner peripheral surface of the frame 2 and around which a stator winding 6 is wound, and 7 denotes the frame 2 located beside the axial end of the stator winding 6. A sheathed heater attached to the inner peripheral surface of the shaft 8, a shaft rotatably supported by the brackets 3 and 4, and a rotor 9 fitted and fixed to the outer peripheral surface of the shaft 8. The sheathed heater 7 is specifically attached as shown in FIGS. 4 and 5. First, a plurality of screw holes are formed on 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 to and supported by the sheath heater supporting portion 10 of the plurality of mounting brackets 12 including the sheath heater supporting portion 10 and the fixing portion 11 having the screw holes, and the fixing portion 11 of the mounting bracket 12 is supported by the frame. It is brought into contact with the inner peripheral surface of 2 and clamped and fixed to the frame 2 by a tightening screw 13.

[0003]

However, the prior art has the following problems. (1) The entire surface of the fixed portion 11 of the mounting bracket 12 is attached to the frame 2
Since the sheathed heater 7 is attached to the inner peripheral surface of the motor, part of the heat generated by the sheathed heater 7 flows to the frame 2 through the mounting bracket 12 and is radiated to the outside air unnecessarily, so that the inside air of the electric motor is lost. The temperature does not rise efficiently. (2) When the capacity of the sheathed heater is increased to raise the temperature of the inside air of the electric motor, the surface temperature of the sheathed heater 7 separated from the mounting metal is increased by that amount, and exceeds the allowable temperature value specified as the explosion-proof electric motor. There is a risk that (3) Since the plurality of mounting brackets 12 are used, the work of mounting the sheath heater 7 is troublesome. The present invention has been made to solve such a problem, and an object of the present invention is to provide a method for attaching a sheath heater that can efficiently raise the internal air temperature of an electric motor.

[0004]

In order to solve the above problems, a method of mounting a sheath heater according to the present invention is a ring-shaped frame, an outer frame composed of a bracket fitted and fixed to the frame, and the frame. In a stator of a rotary electric machine, which is fitted and fixed to the inner peripheral surface of the stator and has a stator core wound with a stator winding, supports a C-shaped sheathed heater, and is at least intermittently cylindrical. A ring-shaped mounting bracket with multiple screw holes formed on the fixed part formed on
Inserted inside the outer frame located beside the axial end of the stator winding, the mounting screw is screwed into the screw hole from the inside, and the tip of the mounting screw is the inner circumference of the outer frame. The fitting is attached to the outer frame by pressing it against the surface.

[0005]

By the above means, the contact area between the mounting member and the outer frame becomes very small, and the heat of the sheath heater hardly flows to the outer frame side.

[0006]

Embodiments 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 sheath heater 7 is attached to the frame 2 as follows. First, as the mounting bracket 14, one that is configured in a ring shape is used instead of using a plurality of small ones. The mounting member 14 has, for example, an L-shaped cross section, and includes a cylindrical fixing portion 15 and a brim-shaped sheath heater supporting portion 16. Screw holes (not shown) are formed in the cylindrical fixing portion 15 at a plurality of locations. The C-shaped sheath heater 7 is attached to the sheath heater support portion 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 is positioned beside the axial end of the stator winding 6. Next, the mounting screw 18 is screwed from the inside into the screw hole of the fixing portion 15 of the mounting bracket 14, and the tip end of the mounting screw 18 is pressed against the inner peripheral surface of the frame 2. By doing so, the attachment 14 is firmly attached to the frame 2 by the reaction force with respect to the frame 2. In addition, in the work of attaching the sheath heater, the work is facilitated by previously attaching the sheath heater 7 and the mounting screw 18 to the mounting bracket 14 to form a separate unit. In such a sheath heater mounting method, the mounting bracket 14 does not contact the frame 2 but only the tip of the mounting screw 18 contacts the frame 2. Therefore, the contact area between the two is very small, and Heater 7
Almost no heat flows to the frame 2. Therefore, the inside air temperature of the electric motor can be efficiently raised. Further, since the screw hole is not formed in the frame 2 and the screw is not tightened in the screw hole, the axial position of the sheath heater 7 can be freely set on the frame 2, and the positioning becomes easy and the mounting position can be improved. You can change it freely. Further, since the surface of the mounting member 14 does not contact the inner peripheral surface of the frame 2 at the mounting position of the sheath heater 7, the dimensional tolerance accuracy and surface roughness accuracy of the inner peripheral surface of the frame 2 can be made rough. If a V-shaped or U-shaped groove is formed in the circumferential direction on the inner peripheral surface of the frame 2 at the position where the sheath heater 7 is attached, the sheath heater 7 can be prevented from being displaced in the axial direction for some reason. it can. In the above embodiment, the frame 2
Although the example in which the sheath heater 7 is attached is shown in FIG. 1, the sheath heater 7 may be attached to the inner peripheral surface of the bracket 3 in an electric motor having a short frame 2 and a long bracket 3. That is, the sheathed heater 7 may be attached to either the frame or the bracket forming the outer frame. Alternatively, the mounting bracket 14 may be ring-shaped only in the fixed portion 15, and the sheath heater supporting portion 16 may be formed intermittently only in the portion to which the mounting piece 17 is mounted, or conversely, the sheath heater supporting portion 1 may be formed.
Only the portion 6 has a ring shape, and the fixing portion 15 has a mounting screw 18
Alternatively, only the portion to which is attached may be formed intermittently. Further, the intermediate portion between the fixed portion 15 and the sheath heater support portion 16 is formed into a ring shape, and the fixed portion 15 and the sheath heater support portion 16 are intermittently provided only at the portions where the mounting screws 18 and the mounting pieces 17 are mounted, respectively. It may be formed. Furthermore, the mounting member 14 may be composed of only the fixing portion 15 formed in a ring shape, and the sheath heater 7 may be fixed to the fixing portion 15 by the mounting piece 17.

[0007]

As described above, the present invention has the following effects. (1) The contact area between the mounting member and the outer frame becomes extremely small, and the heat of the sheathed heater hardly flows to the outer frame side, so that the inside air temperature of the electric motor can be efficiently raised. (2) Processing and assembling work for attaching the sheathed heater are simplified.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a mounting portion of a sheathed heater in an embodiment of the present invention.

FIG. 2 is a front sectional view showing an attachment portion of the sheathed heater in the embodiment of the invention.

FIG. 3 is a side view showing an electric motor in a conventional example, showing an upper half portion 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 an attachment portion of a sheathed heater in a conventional example.

[Explanation of symbols]

1 Outer Frame 2 Frame 3, 4 Bracket 5 Stator Iron Core 6 Stator Winding 7 Sheath Heater 8 Shaft 9 Rotor 14 Mounting Bracket 15 Cylindrical Fixing Part 16 Sheath Heater Supporting Part 17 Mounting Piece 18 Mounting Screw

Claims (1)

[Claims] 1. A stator core having a ring-shaped frame, an outer frame composed of a bracket fitted and fixed to the frame, an inner peripheral surface of the frame fitted and fixed, and a stator winding wound around the stator core. In a stator of a rotating electric machine having: a ring-shaped fitting for supporting a C-shaped sheathed heater, and at least intermittently forming a plurality of screw holes in a fixed portion formed in a cylindrical shape, It is inserted inside 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, and the tip of the mounting screw is attached to the inner peripheral surface of the outer frame. A method for mounting a sheathed heater, characterized in that the mounting bracket is mounted on the outer frame by pressing against.