JPS58124080A - Motor for compressor - Google Patents

Abstract

PURPOSE:To realize the heavy load starting of the compressor after being left for a long period of time with a torque substantially same as that upon normal operation by a method wherein a pressure which is connected in parallel to a PTC (positive characteristic thermistor) connected in series to an auxiliary coil and is operated by a predetermined pressure. CONSTITUTION:In case the compressor is started, the PTC3 is operated at first and the conduction of the auxiliary coil 2 by the circuit of the PTC is interrupted, the pressure switch 5 continues the condition of ON when the internal pressure of a case 7 for the compressor is higher than the set pressure of the pressure switch 5, therefor, the auxiliary coil 2 is excited successively and the condition of high torque due to double-phase operation is continued. When the internal pressure of the case has arrived at a pressure below said set pressure, the pressure switch 5 is put OFF and a normal operation is begun. Accordingly, the maximum torque of the motor is enough to be small as the torque upon operation under the set pressure of the pressure switch 5 or the operation under conducting the auxiliary coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to an electric motor for a compressor in the Ministry of Air Conditioning and the like.

Prior art In general, the load on the compressor and the fall pressure P8 are the first
The relationship is as shown in the figure, and when the compressor is used for cooling operation of an air conditioning system, the discharge pressure Pd and suction pressure Psl during normal operation, and the discharge output pressure Pd at startup after a long period of discharge. ,
and suction pressure Ps! The pressure changes as shown in FIG. 2 due to the difference between the normal balance pressure P1 and the long-term standstill balance pressure P.

On the other hand, in the conventional closed-type electric motor for pressure bales, as shown in the third example, an auxiliary coil 2 is connected in parallel to the main coil 1 via a PTC (positive characteristic thermistor) 3. P
For starters including TC3, if the starter is started directly at the time,
Since the circuit at point A in Fig. 2 also operates long ago (PTC 3 exhibits a pre-resistance of +a, and the current to the auxiliary coil 2 is effectively vc), this is not suitable for starting after being left unused for a long time. In the case of starting during noise operation, a very large torque is required, and when more than 10 cycles have passed after starting, a pressure much larger than that during normal operation appears as shown in B.

Therefore, as a friend that guarantees startup even after being left unused for a long time,
Unfortunately, it is necessary to use a torque that is much larger than the torque required during normal operation, which deteriorates the efficiency of motor use during normal operation, and also causes an increase in costs. The present invention has been made in view of the above point, and it is possible to realize a start-up after being left under a heavy load for a long time with approximately the same torque as during normal operation, and thus the above-mentioned An object of the present invention is to provide an electric motor for a compressor in which the above problems are solved.In order to achieve the above object, the present invention provides a PTC connected in series to an auxiliary coil. , connect the pressure switch,
The pressure switch is operated at a predetermined pressure - Examples The present invention will be explained in detail below using examples.

Figure 44 shows an example of an excitation circuit for an electric motor.
This is a circuit diagram in which a series circuit consisting of a resistor 4 and a pressure switch 5 is connected in parallel to a PTC 3 connected in series to an auxiliary coil 2. The pressure switch 5 is a Sakaki-type pressure switch whose contacts are turned on and off by the expansion and contraction of a bellows, which is housed in a case containing foot pressure. The set pressure is set at a pressure slightly higher than the balance pressure P during normal operation shown in Figure @2, and the contact is designed to turn off below the on level at +'KJ constant pressure or above. Note that the pressure for expanding and contracting the bellows of the pressure switch 5 depends on the pressure of the compressor, and when the pressure switch 5 is housed in the case 7 in the compression area or is installed in the case 7, the pressure shown in the fifth example is as follows. Next, the pressure switch 5 is connected to the total pressure - Iso through the capillary tube 6 so that the pressure switch 5 receives the fluctuation of the internal pressure of the compressor case 7. With the above, the pressure switch 5 is activated. However, even if the PTC 3 operates first and the auxiliary coil 2 is not energized by its circuit, the internal pressure XI', -e a of the case 7 of the compressor
f If the pressure is higher than the set pressure of the pressure switch 5, IJil
Since the El Nucatch 5 is turned on, the auxiliary coil 2 is turned on and excited, and the high torque due to the two-phase λ rotation continues; the D state continues, and the pressure inside the case rises to below the set pressure (-). If so, pressure switch 5 is turned off and positive), 4
It becomes driving. Also, during operation, the suction pressure P12 is A 2
As shown in Figure 1, when the pressure rises to a high load state, the pressure switch 5 is turned on and the auxiliary coil 2 is energized to generate a large torque, so that breakdown can be avoided. Can be done. As a result of the above, the maximum torque of the electric motor is a small value that is approximately the same as the torque at the set pressure of the pressure switch 5, that is, during normal operation. Note that during normal operation, the pressure switch 5 remains off, and startup operation is performed in the same pattern as the conventional one. Furthermore, during the two-phase operation, the resistor 4 is inserted into the loop of the auxiliary coil 2 after the PTC3 is operated, so the current is suppressed and there is no risk of burnout or the like due to a rise in the temperature of the auxiliary coil 2.

FIG. 6 shows the starting characteristics in comparison with the conventional one, where the broken line shows the change in the load applied to the compressor, and the solid line shows the change in the torque of the electric motor. In the case of the conventional example, if the load is still large after startup, the three PTCs operate to reduce a-
4b (PTC?'I: WORK)→C, but in the case of this example, a − + b (P T
Cf'j'' shift) → e (continuation of two-phase operation) → f (pressure switch off) → g (steady operation), resulting in a violation of city regulations. coil 1
and auxiliary coil 2 common power are shown.

As explained above, according to the invention, the maximum torque can be reduced, so the operating efficiency of the electric motor can be increased as well as the miniaturization can be achieved.
Cost reduction can be achieved.It can also survive the linear pressure (point B) that occurs several seconds after startup immediately after long-term release.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the relationship between compressor suction pressure and load, Figure 2
The figure shows the timing diagram of the pressure output when starting the pressure a machine during cooling operation. Figure 3 is the 1141 path diagram of the conventional '-kankai excitation a circuit,
Figure 4 shows one IC of an electric motor according to an embodiment of the present invention! l! M
FIG. 5 is a circuit diagram of a simultaneous excitation button of another embodiment, and FIG. 6 is a starting characteristic diagram of the compressor and 1-IT operation during cooling operation. l... King coil, 2... Auxiliary coil, 3... PT
C. 4... Grinding resist, 5... Pressure switch, 6... Capillary tube. Applicant's agent Inomata Eraser Figure 1 Figure 8 Figure 5 Figure 7 ( □Closing

Claims (1)

[Claims] 1. An excitation circuit is constituted by a main coil and an auxiliary coil in which a positive characteristic thermistor is connected in series. 6. An electric motor for compression rock fishing, in which a pressure switch is connected to the thermistor ζ parallel to U. a pressure switch, characterized in that the pressure switch is operated by the pressure of the compressor.
Horizontal electric smoker 2, the above pressure switch is connected to the thermistor Km row through a resistor 1 and 4! As a sign, end! Fl
! + Electric motor 03 for a compressor according to claim 1 qfI characterized in that the pressure switch is housed in a sealed case of the compressor and receives pressure.
4. The electric motor for an rE compressor according to claim 1, wherein the pressure switch is provided outside a sealed case of the compressor and receives the pressure inside the sealed case via a capillary tube. 5. The electric motor for a compressor according to claim 1, characterized in that the pressure switch is activated at a pressure slightly higher than the lance pressure during normal operation. 'IIt for a compressor according to claim 1 characterized in
motive