JPH0118862Y2 - - Google Patents

Description

[Detailed description of the invention] This invention relates to air conditioners such as heat pump air conditioners and heaters, and particularly when the capacity of an electric compressor is controlled by changing the number of poles of the electric motor, burnout due to spark flash of wiring equipment The present invention relates to a protection device for an air conditioner that is capable of preventing accidents such as the above, and performing reliable and smooth pole number change.

In a multi-room air conditioning system in which multiple indoor units are connected in parallel to one outdoor unit, the cooling capacity will vary depending on whether, for example, only one room is being cooled or two rooms are being cooled at the same time. Naturally, there are differences in terms of performance, and in small-capacity equipment for general household use, the compression capacity is usually controlled by switching the rotation speed of the electric motor connected to the compressor between high and low speeds. ing.

In this type of equipment, a pole-converting 2-speed motor is often used as the compressor motor, but when converting the motor speed by switching the pole number, for example, 2-pole or 4-pole 2-speed motors are used. Thinking about a motor, if you quickly switch from a high-speed pole to a low-speed pole or vice versa, if you turn on the other electromagnetic switch before the arc that occurs when one electromagnetic switch opens is completely extinguished, the arc A short circuit accident occurs.

Therefore, in order to change the rotation speed, it has traditionally been necessary to take appropriate timing.
Current control circuits rely solely on a mechanical delay activation method that uses auxiliary relays to obtain this timing, so although it is possible to obtain sufficient timing to prevent spark flash, this time is measured in seconds. Because of the length, it is necessary to stall once and then turn on at low or high speed, which causes an excessive starting current to flow and unsmooth switching, which is undesirable.Furthermore, the load at startup is large and may cause startup failure. There was still some dislike that the drawbacks, such as nuisances, still remained unresolved.

Focusing on these facts, the present invention was developed as a result of various studies to eliminate the shortcomings of conventional devices, and is particularly suitable for use as an operation control device for a two-speed motor with variable number of poles used as a prime mover for a compressor. , a contact-type interlock protection mechanism attached to both high- and low-speed magnetic contactors and two delay time circuits, one for long and one for short, are used in combination with mechanical and electronic devices. Equipped with a double interlock safety device, and in addition, sufficient starting torque is guaranteed when switching from low-speed pole to high-speed pole, and switching is performed using a short-time delay circuit corresponding to the time required for the arc at the magnetic contactor to disappear. On the other hand, when switching from a high-speed pole to a low-speed pole, taking into account the reduction in starting torque, the compressor's pressure difference between high and low pressures must be adjusted in a manner commensurate with the time it takes for the pressure difference to decrease to a pressure difference sufficient to restart at the low-speed pole. It is characterized by a configuration in which switching is performed by a long delay circuit.

The specific content of the present invention having such features will be described in detail below with reference to the accompanying drawings.

Since the air conditioner according to the present invention, for example, a multi-room heating and cooling system, is a well-known refrigeration circuit, it is not shown in the drawings, but will be briefly described below.

A plurality of indoor units (two in this example) are connected in parallel to one outdoor unit by gas pipes and liquid pipes, and branch liquid pipes and branch gas pipes are connected to each indoor unit. By opening and closing a liquid-side solenoid valve and a gas-side solenoid valve, which are respectively installed, the corresponding indoor units are started and stopped.

It is preferable that the compressor installed in the outdoor unit is capable of changing its compression capacity depending on the number of operating indoor units, so the motor 1 directly connected as the prime mover is replaced with a pole-converting two-speed motor, for example, a four-pole motor. It is configured with a 2-pole motor 1, and when high capacity is required, it is operated with 2 poles (3600 times/min in 60Hz area), while when low capacity is required, it is operated with 4 poles (same as
1800 times/min).

As shown in Fig. 3, the torque characteristics of the compressor driven by the 4-pole-2-pole motor 1 have a large difference between the 4-pole and 2-pole motors. Starting the compressor requires an excessive amount of starting torque, and the pressure difference between the discharge and suction is quite large immediately after the compressor stops, so starting immediately after the compressor stops requires an extremely large starting torque. I need.

Therefore, when switching from 4-pole to 2-pole or vice versa, it has been conventional practice to take appropriate timing. The circuit is formed by a strong current circuit section shown in the first figure and a weak current circuit section shown in the second figure.

This operating circuit will be explained in sequence below. In FIG. It is interposed in the stator winding circuit of the pole motor 1.

Between the control buses L ₁ and L ₂ , each electromagnetic contactor 4, 5,
Coils 6 and 7 4s, 5s, 6s, 7s, outdoor fan motor 8, four-way switching valve solenoid 9 that is set to the cooling cycle when energized, and cooling/heating operation relay 1 provided corresponding to each indoor unit.
0, 11, cooling/heating switching relay 12, operation switch S _WA , S _WB of each indoor unit, fan motor 13, 14 of each indoor unit, indoor thermostat 1
5 and 16 and a low voltage power supply transformer Tr are electrically connected to each other.

The coil 7s and the outdoor fan motor 8 are energized when at least one of the cooling/heating operation relays 10, 11 is excited, that is, when cooling or heating operation is required. On the other hand, the coils 4s and 5s are energized by a two-pole relay 17, which will be described later, and their contacts 17a
is closed and the coil 6s is deenergized, so that the contact 6b
is energized to rotate the motor 1 with two poles when it is closed.

The coil 6s is energized by a 4-pole relay 18, which will be described later, and its contact 18a is closed, and the coil 4
When contacts 4b and 5b are closed due to the deenergization of s and 5s, the contacts 4b and 5b are energized to rotate the motor 1 with four poles.

The solenoid 9 is energized by the closing of the contact 12a as the cooling/heating switching relay 12 is energized, and operates to switch the refrigeration circuit to the cooling cycle.

The air-conditioning/heating operation relays 10, 11 are energized by the operation commands of the indoor thermostats 15, 16 for cooling/heating in each indoor unit.Although not shown in Fig. 1, this energization causes the gas side of the corresponding indoor unit to be activated. It is also used as a relay to open the liquid side solenoid valve.

The cooling/heating switching relay 12 is energized when at least one of both indoor units is switched to cooling operation, setting the four-way selector valve to the cooling cycle side, and the contact 12c is activated to switch between cooling operation and heating operation. In this case as well, it functions as a switching element of a circuit that switches the operation of the compressor, the details of which will be described later.

The low voltage power supply transformer Tr has an operation switching circuit PC connected to the secondary low voltage terminal to change the number of poles, and the compressor capacity is controlled by the circuit PC. There is.

FIG. 2 shows the essential parts of the operation switching circuit PC developed, and the circuit PC includes two-pole relays 17 and 4.
pole relay 18, low pressure/traction switch 19 as a command device that switches between 2 poles and 4 poles during cooling, high pressure/traction switch 20 as a command device that switches between 2 poles and 4 poles during heating, and auxiliary relay 21. , a short-time delay circuit 2, and a long-time delay circuit 3.

In addition, the two indoor thermostats 15 and 16, the cooling/heating switching relay 12, and the low pressure switch 19
A load detection circuit is formed by the high pressure switch 20 and the auxiliary relay 21, and depending on the degree of air conditioning load, a high load signal (indicating the open state of the contact 21a) and a low load signal (conversely, the closed state) is generated. (indicating the state of completion).

The short-time delay circuit 2 includes an AND gate (AND), a charging circuit 22, and an output transistor _Q2 , and if both inputs applied to the input terminals of the AND gate (AND) are logic "H", Charging of the charging circuit 22 is started, and as time elapses for about 25 msec, the potential of the part increases, and the transistor
It operates to make _Q2 conductive and energize the two-pole relay 17.

Note that the conditions for the AND gate (AND) to perform a logical product and output a logic output "H" are when the following two conditions are met.

Specifically, one is that during cooling, the low-pressure force switch 19 opens the contact at a predetermined pressure or higher, and during heating, the high-pressure force switch 20 opens the contact at a predetermined pressure or lower, both of which result in a large air conditioning load. For example, when two indoor units operate simultaneously, the contact 21a is opened by deenergizing the auxiliary relay 21. Another problem is when the long delay circuit 3 is inactive. This means that a logic output "H" is generated from an inverter (INV) which will be described later.

Next, the long delay circuit 3 includes a discharge circuit 23, an operational amplifier (IC), an inverter (INV), and an output transistor _Q1 , and the discharge circuit 2
3 gradually discharges its charge, and when the potential of the part decreases after about 1 minute, a logic output "H" is generated from the operational amplifier (IC), which makes the output transistor Q ₁ conductive and turns on the 4-pole relay 18. is energized, while the output "L" inverted by the inverter (INV) is applied to the input terminal of the AND gate (AND).

Note that the discharge circuit 23 starts charging when the contact 21a changes from closed to open.
Since it takes about 0.6 seconds for the non-inverting input terminal of the operational amplifier (IC) to reach the predetermined "H" level, the transistor _Q1
switches to non-conducting, and then after a period of 25 msec, transistor _Q2 becomes conductive.

On the other hand, the discharge circuit 23 starts discharging when the contact 21a changes from open to closed, and after about one minute, the transistor _Q1 becomes conductive.

The mutual relationship between the operations and potential changes of each part in the operation switching circuit (PC) having such a structure is clarified by the time chart shown in FIG.

Next, to explain the operation mode of the air conditioner, the contact 10a or 11a is closed by operating the switch S _WA or S _WB indoors, and the fan motor 8 and compressor motor 1 are energized and started to operate. After the 1-room operation changes to 2-room operation, or the air conditioning load increases, the low pressure switch 19 changes from closed to open (during cooling), or the high pressure switch 20 changes from closed to open. (during heating), the auxiliary relay 21 is deenergized and the contact 21
When a opens, the transistor _Q
becomes non-conductive, the long-time delay circuit becomes inactive, the 4-pole relay 18 is deenergized, the 4-pole rotating electromagnetic contactor 6 is instantaneously released, and the motor 1 is energized during 4-pole operation. is cut off.

At the same time as the transistor Q ₁ becomes non-conductive, the AND gate (AND) operates and the charging circuit 22 starts charging, and when 25 msec has elapsed, the transistor Q ₂ becomes conductive, that is, the short-time delay circuit 2 counts up to 2. The pole relay 17 is energized.

Thus, the two-pole rotating electromagnetic contactors 4 and 5 are turned on to energize the motor 1 on the two-pole side.

At this time of energization, the compressor has not completely stopped due to inertia, and moreover, the arc generated when the electromagnetic contactor 6 is released has already been extinguished.

Therefore, short-circuit accidents do not occur, and smooth switching from four poles to two poles is achieved.

Note that the one shown in the second figure is the short time delay circuit 2.
Long time delay circuit 3 for starting counting (starting time measurement)
Since the operation is performed under the condition that the low-speed operation command signal for operation at the low-speed pole is erased after charging is completed, the contact of the electromagnetic contactor 6 for the low-speed pole and the electromagnetic contactor 4 for the high-speed pole , 5 can be closed at the same time, and there is an advantage that the arc can be completely extinguished while preventing the compressor from stopping during speed increase.

On the other hand, when the operation changes from two-room operation to one-room operation, or when the air conditioning load is reduced, the auxiliary relay 21 is energized and the contact 21a is closed, so that the transistor Q ₂ is instantaneously activated. Then, the short time delay circuit 2 is reset, the two-pole relay 17 is deenergized, the electromagnetic contactors 4 and 5 are released, and the power to the motor 1 during the two-pole operation is cut off.

Discharge circuit 2 at the same time as transistor Q ₁ becomes non-conductive
3 starts discharging, and after 1 minute the transistor
When _Q1 becomes conductive, the long delay circuit 3 counts up and energizes the four-pole relay 18.

Thus, the electromagnetic contactor 6 is turned on to energize the motor 1 on the four-pole side, but at this point the compressor is started from a completely stopped state.

However, during this one-minute period, the pressure difference between the high pressure and low pressure of the compressor gradually decreases, and the pressure difference has decreased to the point where there is no problem in restarting the compressor with 4 poles. , there are no problems when starting up.

As described in detail above, the present invention provides an operating circuit for switching the pole-converting two-speed motor 1, which serves as the prime mover of the compressor, from high speed to low speed and vice versa. A short-time delay circuit 2 delays the arc according to the time it takes for the contact to extinguish the arc, and when switching from a high-speed pole to a low-speed pole, the pressure difference between the high and low pressures of the compressor is suitable for restarting at the low-speed pole. Equipped with a long-time delay circuit 3 that delays the pressure difference in proportion to the time it takes for the pressure to drop, when switching to high speed, the compressor can be operated almost continuously, eliminating the reduction in capacity during switching.

On the other hand, when switching to a low speed, it is possible to not only prevent contacts from burning, but also to prevent damage such as shaft breakage to the compressor due to generation of reverse braking torque due to switching while rotating under inertia. obtain.

In addition, a contact type interlock mechanism is provided between the two types of electromagnetic contactors 4, 5 and 6, and a non-contact type interlock mechanism is also provided between both the delay circuits 2 and 3. By having heavy safety equipment, equipment can be fully protected.

Furthermore, by forming both delay circuits 2 and 3 into electronic circuits as in the embodiment, the present invention not only provides a compact control device and reduces costs, but also enables the use of mechanical auxiliary relays. It is possible to eliminate the drawbacks of conventional devices of this type that have been used, which have poor reliability and cannot form short-time delay circuits, making complete stop of the compressor unavoidable, especially when switching speeds up. .

As described above, the present invention is an air conditioner control device that can exhibit various excellent features.

[Brief explanation of the drawing]

FIG. 1 is a high-power circuit of an air conditioner according to an example of the device of the present invention, FIG. 2 is a low-power circuit, FIG. 3 is a torque characteristic diagram of the compressor in the air conditioner, and FIG. It is a time chart showing the operating state of the illustrated circuit section. 1...Pole number conversion type 2-speed motor, 2...Short time delay circuit, 3...Long time delay circuit, 4, 5...Magnetic contactor for high speed poles, 6...Magnetic contactor for low speed poles,
4b, 5b, 6b...Interlock contacts.

Claims (1)

[Claims for Utility Model Registration] In an air conditioner having a compressor driven by a pole-converting two-speed motor 1, there is provided a high-speed pole electromagnetic contactor 4 for operating the two-speed motor 1 at a high-speed pole; 5, a low-speed pole electromagnetic contactor 6 for operating the two-speed motor 1 at a low-speed pole, and simultaneous input between the high-speed pole electromagnetic contactors 4 and 5 and the low-speed pole electromagnetic contactor 6. In order to limit the load, interlock contacts 4b, 5b, 6b are provided in each electromagnetic contactor 4, 5, 6, respectively, and a load that detects the air conditioning load and switches and transmits a high load signal and a low load signal. a detection circuit, which starts charging by transmitting the high load signal, erases a low speed operation command signal for turning on the low speed pole electromagnetic contactor 6, and transfers the charged charge by transmitting the low load signal; A predetermined discharge completion time of about 1 minute, which corresponds to the time it takes for the high-low pressure difference in the compressor to decrease to a value suitable for restarting at the low-speed pole when switching from the high-speed pole to the low-speed pole after discharging. The long-time delay circuit 3 outputs the low-speed operation command signal as a result of the passage of time, and the high-speed operation command signal for turning on the high-speed pole electromagnetic contactors 4 and 5 is erased by the transmission of the low-load signal; , when the long delay circuit 3 has completed charging and the high load signal is transmitted, charging is started, and when switching from the low speed pole to the high speed pole, an arc is generated at the contact of the electromagnetic contactor 6 for the low speed pole. 1. A control device for an air conditioner, comprising: a short time delay circuit 2 that outputs the high-speed operation command signal after a predetermined charging time of approximately 25 msec corresponding to the time for the arc to be extinguished.