JPS6135791B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a starting circuit for high-efficiency refrigerant compressors such as refrigerators and room air conditioners, which has improved starting characteristics.

In recent years, energy conservation has become a hot topic in many fields, and energy conservation has also become a priority in refrigeration equipment such as refrigerators and room air conditioners. As one method for this, it is effective to significantly improve the efficiency of the refrigerant compressor, and therefore priority is given to improving the efficiency of the refrigerant compressor during rated operation. For this reason, the compressor drive motor is also designed with top priority given to improving efficiency during rated operation, so starting performance is reduced, and if the power supply condition is poor, there is a risk that starting failure may occur. The starting circuits of these conventional refrigerant compressors are shown in Figures 1 and 2.
This will be explained using figures. 1 is a main coil of a motor for driving a refrigerant compressor, and 2 is an auxiliary coil. An operating capacitor 3 is connected in series to the auxiliary coil 2, and a series circuit of the auxiliary coil 2 and the operating capacitor 3 is connected to the main coil 1 in parallel. 4 is voltage relay 5
This drive coil is connected in parallel with the auxiliary coil 2. 6 is a motor starting capacitor, one end of which is connected to the connection point between the auxiliary coil 2 and the driving capacitor 3, and the other end connected to the normally closed contact 5 in the voltage relay 5.
Connect to b. A common terminal 5c within the voltage relay is connected to a power line. 7 is a refrigerant compressor operation switch, and 8 is a general commercial power source. The starting operation of this conventional compressor will be explained. When the operation switch 7 is turned on, a starting inrush current flows through the main coil 1 of the compressor drive motor, and at the same time, the inrush current flowing into the auxiliary coil causes the operation capacitor 3, motor starting capacitor 6, and voltage relay 5 to be normally closed. The current flows in a branched manner to contact 5b, and the motor starts as a capacitor-starting single-phase induction motor. When the rotational speed of the motor increases, the voltage between the terminals of the auxiliary coil increases, and the voltage applied to the drive coil 4 of the voltage relay 5 connected in parallel with the auxiliary coil 2 also increases.
By setting the voltage between the auxiliary coil terminals at the time when the motor is sufficiently accelerated to the operating voltage of the voltage relay 5, when the voltage relay 5 is turned on, the contact 5b in the voltage relay opens, disconnecting the motor starting capacitor 6, and starting the motor. Switch to a capacitor-operated single-phase induction motor using capacitor 3. At this time, the motor specifications determine the capacitor capacity for operation so that maximum efficiency is achieved at the rated rotation speed. Furthermore, in order to increase the initial starting torque when the rotational speed is 0, the capacity of the starting capacitor 6 must be increased. If the capacity of the starting capacitor 6 is made too large, the voltage between the terminals of the auxiliary coil increases when the motor rotation speed is 0, making it necessary to set the operating voltage of the voltage relay 5 high. Generally used voltage relays resist the repulsive force of springs,
By increasing the magnetic attraction force generated by the drive coil, the relay is turned on, and when the voltage applied to the drive coil becomes smaller and the spring repulsion force becomes stronger, the relay returns to off. Normally, the return voltage of the drive coil is about 60 to 65% of the operating on voltage. If increasing the efficiency at the motor's rated rotational speed is given top priority, the speed-torque characteristic curve of a single-phase induction motor may have a dent in the torque at low speeds, resulting in a decrease in acceleration torque, so increase the starting capacitor capacity. ing. After the motor is started, the voltage between the auxiliary coil terminals increases and the voltage relay 5 is turned on. Immediately after the motor starting capacitor is disconnected, the capacitor capacity becomes extremely small, so the impedance of the capacitor increases, and the voltage between the auxiliary coil terminals increases. Decrease. When this voltage becomes lower than the return voltage of the voltage relay 5, the voltage relay that was once turned on is turned off again and the contact 5b is closed, so that the motor starting capacitor 6 is connected again, and the voltage relay is turned on again.

An example of this operation will be explained in more detail with reference to FIG. The curve VAS (Cr + Cs) in Figure 2 is the voltage between the auxiliary coil terminals when the operating capacitor (Cr) and motor starting capacitor (Cs) are connected, and VAS (Cr) is the operating capacitor (Cr). ) is the voltage between the auxiliary coil terminals when only the auxiliary coil is connected. In both cases, the voltage value increases as the motor rotation speed increases. At the moment of starting, voltage relay 5
Since the motor starting capacitor (Cs) is connected through the normally closed contact 5b, the VASO voltage is applied to the voltage relay drive coil 4. When the motor is started and point _A1 is set as the operating voltage of voltage relay 5, the voltage applied to voltage relay drive coil 4 is turned on at VAS ₁ corresponding to point _A1 . When voltage relay 5 is turned on, contact 5b opens and disconnects the motor starting capacitor (Cs), so the voltage relay drive voltage moves from point _A1 to point _A2.At this time, _A2
Since the point becomes below the reset voltage (point R) of the voltage relay 5, the voltage relay 5 is turned off and moves to point _A3 , and when the starting capacitor 6 is disconnected again, the voltage applied to the voltage relay driving coil becomes the reset voltage R. A ₃ ―A ₄ ―A ₅ ―A 6 ―A 7 ―A 3 ―A 4 ―A ₅ ―A 6 ―A ₇ ―r point and turn on,
This phenomenon of off-operation becomes more pronounced as the starting load of the compressor increases. As mentioned above, in the conventional refrigerant compressor starting circuit, when the ratio of the operating capacitor capacity to the motor starting capacitor capacity increases, the voltage relay turns on and off frequently during starting, which significantly shortens the life of the voltage relay contacts. There was a flaw in that.

The present invention has been made to improve the above defects. An impedance element is connected in series with the drive coil of the voltage relay, and the voltage between the auxiliary coil terminals is raised when the voltage relay is turned on.When the voltage relay is turned on, the starting capacitor is switched through the contacts in the voltage relay at the same time. This eliminates the voltage sharing of the impedance element inserted in series with the voltage relay drive coil, maintains the voltage applied to the voltage relay drive coil above the return voltage, and ensures reliable starting with a single operation.

The present invention will be explained with reference to an embodiment shown in FIG. Components with the same reference numerals as those in the conventional example are the same. 9
is an impedance element such as a resistor or a reactor, and is inserted between one end of the voltage relay drive coil 4 and the connection point between the auxiliary coil 2 and the operation capacitor 3. The common terminal 5c in the voltage relay is connected to the connection point between the auxiliary coil and the operating capacitor, the normally open contact 5a is connected to one end of the voltage relay drive coil 4 and the connection line of impedance 9, and the normally closed contact 5b
is connected to one end of the motor starting capacitor 6, and the other end of the motor starting capacitor 6 is connected to the driving capacitor side power supply line. The series circuit of the auxiliary coil 2 and the operating capacitor 3 is connected in parallel with the main coil 1. The operation of this embodiment configured as described above will be explained with reference to FIG. When the compressor operation switch 7 is turned on, a starting inrush current flows into the main coil 1 of the motor, and at the same time, the inrush current that flows into the auxiliary coil 2 passes through the operating capacitor 3 and contacts 5c-5b in the voltage relay 5 to start the motor. The motor is started as a capacitor-started single-phase induction motor. After the motor starts, the auxiliary coil terminal voltage increases along the VAS (Cr+Cs) curve. A The voltage VAS ₁ at _one point is the operating voltage of the voltage relay, but since an impedance element 9 such as a resistor or reactor is connected in series to the drive coil 4 of the voltage relay, the voltage of VAS ₁ is the same as the impedance element and the drive coil 4 of the voltage relay. The voltage is divided into coil 4, and it does not operate at _one point A. When the motor rotation speed further increases and the auxiliary coil terminal voltage reaches point _B1 , the voltage across the terminals of the voltage relay drive coil 4 increases.
When VAS ₁ is reached and the voltage relay 5 is turned on, opening the contact 5b and disconnecting the starting capacitor 6, the impedance element 9 is adjusted so that the voltage between the auxiliary coil terminals becomes higher than the return voltage R of the voltage relay 5. By setting the impedance value,
B Move from point ₁ to point r. At this time, the impedance elements were simultaneously shot through contacts 5c and 5a, so that the voltage relay drive coil had r
By being able to apply a voltage corresponding to the point, a voltage higher than the return voltage R can be applied, the voltage relay 5 can be kept in the on state, and the motor can be reliably started.

Note that when the voltage relay 5 is turned on, the shared voltage of the impedance element 9 is VAS ₂ - VAS ₁ ,
After the voltage relay turns on, the shared voltage becomes 0.
When the operation has shifted to point r, the motor starting capacitor 6 is disconnected, and the compressor can be operated as a capacitor starting capacitor operation type single-phase induction motor.

Next, another embodiment of the present invention will be described with reference to FIG. 5. Two double-throw switches are provided within the voltage relay 5'. One switch is connected in the same way as in the above embodiment, the common terminal 5'-2c of the other switch is connected to the power supply side to which the operating capacitor 3 is connected, and the normally open contact 5'-2a is connected to the main coil 1 and the reactor 10.
The reactor 10, which is connected to the connection wire of This is different from the previous embodiment in that one voltage relay 5' disconnects the starting capacitor 6 and at the same time shorts the impedance elements. Starting inrush current limiting reactor 1 inserted in series
This has the effect of shorting the 0 terminals and limiting the starting inrush current.

Further, another embodiment of the present invention will be explained with reference to FIG. 6. Normally closed contacts 5'--
1b, the drive coil 4' of the voltage relay 5' and the impedance element 9 are connected in series, and the normally open contact 5'-1a is shared with the common terminal 5'-2c.
Connect to the power line that connects the operating capacitor 3. The other normally closed contact 5'-2b in the voltage relay 5' is connected to one end of the motor starting capacitor 6, and the other end of the motor starting capacitor 6 is connected to the connection line between the auxiliary coil 2 and the operating capacitor 3. . Further, the normally open contact 5'-2a is connected to a line connecting the main coil 1 and the reactor 10. The difference from the previous embodiment is that the voltage relay driving coil 4' and the impedance element 9 are connected in series until the voltage relay 5' is turned on, and the voltage relay driving coil 4' and the impedance element 9 are connected in series until the voltage relay 5' is turned on. ' is turned on, the impedance element 9 is disconnected at the same time as the voltage relay 5' is turned on, and the power supply voltage is applied to the voltage relay driving coil 4', so that the return voltage of the voltage relay 5' is lower than the power supply voltage. In this case, the voltage relay 5' can be reliably held in the on state by the power supply voltage, which has the effect of facilitating the setting of the voltage relay drive voltage.

In the starting circuit of a compressor with a built-in capacitor-operated single-phase induction motor, the present invention connects a series circuit of a voltage relay drive coil and an impedance element in parallel with the auxiliary coil of the motor, and after the motor starts, the voltage relay Since the motor starting capacitor is disconnected through the contact point of the motor and the shared voltage of the impedance element is eliminated at the same time, the motor is designed with top priority on increasing the rated operating efficiency of the compressor, and the torque is reduced at low speeds on the speed-torque curve. Even if there is a recess, the motor starting capacitor can be disconnected in a timely manner even if the capacitance ratio between the operating capacitor and the starting capacitor is large, which ensures reliable starting and has a great effect on mass production. be.

According to this embodiment, since the motor starting capacitor is connected to the normally closed contact in the voltage relay and the impedance element is connected between the normally open contacts, the starting capacitor is disconnected and at the same time the impedance elements are short-circuited, and the auxiliary coil This has the effect of correcting the drop in voltage between terminals.

Further, according to this embodiment, since the power supply voltage is applied to the drive coil of the voltage relay at the same time as the starting capacitor is disconnected, the voltage relay can be easily held and the starting can be ensured.

[Brief explanation of the drawing]

Fig. 1 is a conventional compressor starting circuit diagram, Fig. 2 is a conventional diagram showing the relationship between motor rotation speed and motor auxiliary coil terminal voltage, Fig. 3 is a compressor starting circuit diagram of the present invention, and Fig. 4 5 is a diagram illustrating the operation of the present invention, FIG. 5 is a starting circuit diagram showing another embodiment of the present invention, and FIG. 6 is a starting circuit diagram showing another embodiment of the present invention. 1...Motor main coil, 2...Motor auxiliary coil,
3... Operating capacitor, 5... Voltage relay, 5'...
Voltage relay, 6... Motor starting capacitor, 9...
Impedance element, 10...reactor.

Claims (1)

[Scope of Claims] 1. In a starting circuit for a capacitor-starting capacitor-operated single-phase induction motor that detects the auxiliary coil terminal voltage of a motor for driving a refrigerant compressor and disconnects the motor starting capacitor, a motor is connected in parallel with the auxiliary coil of the motor. An impedance element is inserted in series with the drive coil of the voltage relay 5 connected to the motor, and after the motor starts, the motor starting capacitor is disconnected via the contact in the voltage relay 5, and at the same time, an impedance element is inserted in series with the drive coil of the voltage relay 5. A starting circuit for a refrigerant compressor characterized by eliminating voltage sharing between connected impedance elements and maintaining a voltage relay 5 in an on state. 2 Connect the normally closed contact in the voltage relay 5 to the motor starting capacitor, connect the normally open contact to the connection point between the motor auxiliary coil 2 and the impedance element 9,
Claim 1, characterized in that when the voltage relay 5 is turned on after the motor is started, the motor starting capacitor is disconnected via the contacts in the voltage relay, and at the same time the terminals of the impedance element are short-circuited.
The starting circuit for the refrigerant compressor described in Section 1. 3 Connect the common terminal of the switch provided in the voltage relay 5' to the drive coil of the voltage relay 5', connect the normally closed contact to the impedance element, and the normally open contact to the power line, and after the motor starts, the voltage relay 5 The refrigerant compressor according to claim 1, characterized in that when ' is turned on, the impedance element connected in series with the voltage relay drive coil is disconnected and at the same time the voltage relay drive coil can be held at the power supply voltage. starting circuit.