JPH01199499A - Closed type motor-driven compressor provided with revolution number detection mechanism - Google Patents

Abstract

PURPOSE:To dispense with gears, a gap sensor, and the like used for the detection of the revolution number of a motor and enable very accurate detection of the revolution number at a low cost by a method wherein not only the motor rotor of an induction motor is made zero in skew but also a search coil is provided to a motor stator. CONSTITUTION:A closed type motor-driven compressor provided with a revolution number detecting mechanism whose compression component 8 is driven by the torque of an induction motor 4 housed in a sealed case 1 is provided, where a motor rotor 3 of the induction motor 4 is made zero in skew. Moreover, a search coil 19 which detects a slotted high frequency ripple induced in a motor stator 2 of the induction motor 4 is provided, and the revolution number of the induction motor 4 is detected by the slotted high frequency ripple detected by the research coil 9. By these processes, gears, a gap sensor, and a connecting member which connects the gears with a crank shaft 5 can be dispensed with, and not only a space that houses these components can be eliminated but also a very accurate revolution number of a motor can be detected.

Description

[Detailed description of the invention] [Industrial use bone P]

The present invention relates to an improvement in a hermetic electric compressor with a rotation speed detection mechanism.

[Conventional technology]

FIG. 6 is a longitudinal sectional view of a conventional hermetic electric compressor with a rotation speed detection mechanism disclosed in, for example, Japanese Unexamined Patent Publication No. 62-71483. In the figure, reference numeral 1 denotes an airtight container, and the airtight container 1 houses a motor 4 comprising a motor stator 2 and a motor rotor 3. A crankshaft 5 at the center of the motor rotor 3 of this electric motor 4 is connected to a compression element portion 8 that is closed and supported by an upper bearing 6 and a lower bearing 7.
The compressor element section 8 is rotated by rotationally driven. Further, the crankshaft 5 on the upper part of the electric motor 4 is provided with a gear 10 at the tip of the connecting member 9 via a connecting member 9. Also, a gap sensor 1 that detects the tooth row of the gear 10
1 is attached to the sealed container 2S1. Further, a suction pipe 12 and a discharge pipe 13 are attached to the closed container l. As the electric motor 4 described above, a generally known induction motor is used. This general induction motor will be explained with reference to FIGS. 7 and 8. FIG. 7 is a cross-sectional view of the stator portion of a typical three-phase induction motor, and FIG. 8 is a vertical cross-sectional view of the stator portion of a typical three-phase induction motor. In the figure, 14 is the stator core, and 15 is the U-phase winding 15.
The stator winding consists of the a and ■ phase windings 15b and the W phase windings 15c, 16 is the rotor core, 17 is the end ring, 1
8 is a rotor conductor. As shown in the figure, the rotor conductor 18 is generally skewed for the purpose of preventing abnormal torque and suppressing electromagnetic noise. In the conventional hermetic electric compressor with a rotation speed detection mechanism configured as described above, the rotational energy of the electric motor 4 is transmitted to the electric motor rotor 3, and the rotational energy of the electric motor 4 is transmitted to the crankshaft supported by the upper bearing 6 and the lower bearing 7. Via the shaft 5, it is transmitted to the compression element section 8. This rotation of the compression element section 8 causes the suction pipe 12 to
The refrigerant gas guided into the compression element part 8 is compressed to a set pressure by the compression element part 8, and is discharged into the space inside the closed container 1, and the refrigerant gas is compressed to a set pressure by the compression element part 8, and is discharged into the space inside the closed container 1. It passes through a space (air gap) or a notch (not shown) in the outer periphery of the motor stator 2, is guided to an external refrigeration device through a discharge pipe 13, and operates as a compressor. In such a conventional hermetic electric compressor with a rotation speed detection mechanism, the electric motor 4 generates a constant torque over time, but the load torque in the compression element section 8 is Since the rotation of the electric motor 4 fluctuates during the compression process from to discharge, the rotation of the electric motor 4 fluctuates, and as a result, the electric motor 4 vibrates and generates noise. In order to prevent this, the rotation speed of the compression element section 8 is detected and the rotation speed of the electric motor 4 is kept constant by an external control circuit. Furthermore, for the purpose of improving the performance of the electric motor 4, a control method using vector control has been proposed.In this case as well, it is necessary to detect the rotational speed of the electric motor 4. For this purpose, as shown in FIG.
The rotation speed of the electric motor A4 is detected by outputting a pulse signal according to the rotation speed.

[Problem to be solved by the invention]

A conventional hermetic electric compressor with a rotation speed detection mechanism is configured as described above, so in order to detect the rotation speed of the electric motor, a gear, a gap sensor, and a connecting member for connecting the gear and the crankshaft are required. This requires a space to store them, and at the same time, the number of these parts increases, making it extremely expensive. This invention was made to solve such a problem, and in order to detect the rotation speed of an electric motor, there is no need for a gear, a gap sensor, or a connecting member for connecting the gear and the crankshaft. It is an object of the present invention to provide a hermetic electric compressor with a rotation speed detection mechanism that can eliminate these storage spaces and at the same time detect the rotation speed of the motor with high accuracy at low cost.

[Means to solve the problem]

The hermetic electric compressor with a rotation speed detection mechanism according to the present invention includes:
In addition to eliminating the skew of the motor rotor of the induction motor, a search coil is provided on the motor stator, and the rotation speed of the induction motor is detected by slot high frequency ripples detected by the search coil.

[Effect]

In this invention, the skew of the motor rotor of the induction motor is made zero, the permeance of the air gap due to the presence of the rotor throttle is made uneven, and slot high frequency ripples are generated, and the slot high frequency ripples cause the motor to rotate. number is detected.

【Example】

An embodiment of the present invention will be described below with reference to FIGS. 1 to 5. FIG. 1 is a longitudinal cross-sectional view of a hermetic electric compressor with a rotation speed detection mechanism according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a stator portion of a three-phase induction motor according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view of a stator portion of a three-phase induction motor according to an embodiment of the present invention. In the figures, the same reference numerals or symbols as those described above indicate the same or equivalent parts, and explanations of the configuration and operation will be omitted as appropriate. Reference numeral 19 denotes a search coil, which is wound around the stator teeth 14a at the - location of the stator core 14. Moreover, the rotor conductor 20 is
As is clear from FIG. 3, it is formed substantially parallel to the longitudinal direction of the motor rotor 3 so that the skew is zero. Therefore, the permeance of the air gap due to the presence of the rotor throttle becomes non-uniform, and so-called slot high frequency ripple ν occurs. This slot high frequency ripple ν is expressed by the following relational expression (a), where St is the number of rotor throttles, P is the number of motor pole pairs, and S is slip. That is, ν=Sz/p(1-s)...
・It becomes (a). From the relational expression (a), the slot high frequency ripple ν is a function of the suberi S, in other words, the rotation speed, and by detecting the slot high frequency ripple number, the rotation speed of the electric motor 4 can be detected. The search coil 19 shown in FIG. 2 is detected as shown in FIG. The waveform detected by the search coil 19 in this way is shaped into a waveform by a filter or the like in an external control device (not shown) as shown in the fifth figure, and then instantaneously determined by measuring the time shown in the figure. The rotation speed of the electric motor 4 can be detected. In addition, in the above-mentioned embodiment, the search coil 19 is
It was wound around one stator tooth 14a of the stator core 14,
It is not limited to this, and any winding method is possible, such as a winding method corresponding to the full pitch of one pole of the l-phase of the stator winding 15, or a winding method in which three sets of search coils are arranged in three phases. It goes without saying that there is.

【Effect of the invention】

As described above, according to the present invention, 1. In addition to eliminating the skew of the motor rotor of the induction motor, a search coil is provided on the motor stator, and the rotation speed of the induction motor is detected by the slot high frequency ripple detected by the search coil, so the rotation speed of the motor can be detected. Therefore, it is possible to eliminate the storage space for gears, gap sensors, and connecting members to connect the gears and crankshaft, and at the same time detect the rotation speed of the motor with high accuracy at low cost. There are excellent effects possible.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal cross-sectional view of a hermetic electric compressor with a rotation speed detection mechanism according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of a stator portion of a three-phase induction motor according to an embodiment of the present invention. FIG. 3 is a longitudinal sectional view of the stator portion of a three-phase induction motor according to an embodiment of the present invention, FIG. 4 is a waveform diagram detected by a search coil according to an embodiment of the present invention, and FIG. 5 is a diagram of the waveform detected by the search coil according to the embodiment of the present invention. A waveform diagram obtained by shaping the waveform detected by the search coil of one embodiment, FIG. 6 is a vertical cross-sectional view of a conventional hermetic electric compressor with a rotation speed detection mechanism,
FIG. 7 is a cross-sectional view of the stator portion of a typical three-phase induction motor, and FIG. 8 is a vertical cross-sectional view of the stator portion of a typical three-phase induction motor. In the figure, l is a closed container, 2 is a motor stator, 3 is a motor rotor, 4 is an electric motor, 5 is a crankshaft, 6 is an upper bearing, 7 is a lower bearing, 8 is a compression element part, 9 is a connecting member, 10 is a gear, 11 is a gap sensor, 12 is a suction pipe, 13 is a discharge pipe, 14 is a stator core, 14a is a stator tooth, 15 is a stator winding, 16 is a rotor core, 17 is an end ring, 1
8.20 is a rotor conductor, and 19 is a search coil. Note that the same reference numerals in each figure indicate the same or corresponding parts.

Claims (1)

[Claims] In a hermetic electric compressor with a rotation speed detection mechanism that compresses gas to a set pressure by rotationally moving a compression element part by the rotational force of an induction motor housed in a hermetic container, the skew of the motor rotor of the induction motor and a search coil for detecting slot high frequency ripples induced in the motor stator of the induction motor, and detecting the rotation speed of the induction motor based on the slot high frequency ripples detected by the search coil. A hermetic electric compressor with a rotation speed detection mechanism.