JP5568046B2 - Air conditioner - Google Patents

Description

  The present invention relates to an air conditioner in which an indoor unit is provided with a drain pump, and particularly relates to an air conditioner that employs a DC low pressure power source type as the drain pump.

As a drain pump used in an indoor unit of an air conditioner, an AC power supply type drain pump has been conventionally used. Recently, a DC low pressure power supply type drain pump with low current consumption has been used to improve APF. Increasing use cases.
In addition, as this kind of prior art, there exist a thing of patent documents 1-3.

JP 2007-303720 A JP 2007-240112 A JP 2004-93003 A

  When drain water that is slimmed and becomes highly viscous is sucked into the drain pump, the drain pump is prevented from rotating and a large lock current flows. In particular, when a DC low pressure power supply type drain pump is used, the power supply circuit is enlarged so that a large current can be supplied on the assumption that a large lock current flows. For this reason, the air conditioner has been increased in size, increased in weight, and increased in cost. Conversely, if the power supply circuit is downsized, less current is supplied, and when the lock current is generated, the voltage supply is stopped due to the operation of the protection circuit in the power supply circuit, etc. There is a risk that.

  An object of the present invention is to obtain an air conditioner capable of preventing the function of the entire product from being stopped while suppressing an increase in the size of a power supply circuit even when a DC low pressure power supply type drain pump is used.

To achieve the above object, the present invention includes a drain pump, the air conditioner having a power supply circuit for driving the drain pump, as well as use a DC low voltage power supply type as the drain pump, the A switching element is provided in a circuit dedicated to the drain pump in which the drain pump is installed, and the drain pump is connected to the power supply circuit through the single switching element, and the switching element is turned on to drain pump is configured to rotate, further provided with a load connected to the other in parallel with the drain pump to the power supply circuit, between the power supply circuit and the DC low voltage power supply type of the drain pump the current limiting means provided in the circuit dedicated to the drain pump the drain pump is installed, the current limiting means, on the temperature A PTC thermistor whose resistance value increases with respect to, the PTC thermistor, after limiting the current, at a current limit value or less current, and Turkey is configured such that current limitation is canceled Features.

  ADVANTAGE OF THE INVENTION According to this invention, even if it uses the direct current | flow low-voltage power supply type drain pump, the air conditioner which can prevent the function stop of the whole product is obtained, suppressing an enlargement of a power supply circuit.

The electric circuit diagram explaining Example 1 of the air conditioner of this invention. The electric circuit diagram explaining the installation place of a current limiting means.

  Hereinafter, specific examples of the present invention will be described with reference to the drawings.

  FIG. 1 is an electric circuit diagram illustrating Example 1 of an air conditioner of the present invention. As shown in this figure, an air conditioner (in this embodiment, an indoor unit) is provided with a DC low pressure power source drain pump 10 and a power circuit 20 for driving the drain pump 10. Further, a current limiting means 30 is provided between the DC low-voltage power supply type drain pump 10 and the power supply circuit 20.

  The DC low-pressure power source drain pump 10 serves to discharge the drain water accumulated in the indoor unit of the air conditioner to the outside of the indoor unit. The power supply circuit 20 may be composed of arbitrary components on a printed circuit board, or may be a ready-made power supply device. The current limiting means 30 provided between the DC low-voltage power supply type drain pump 10 and the power supply circuit 20 is a PTC (positive temperature coefficient) thermistor whose resistance value increases with increasing temperature, It is preferable that the relationship between temperature and resistance value is non-linear. When a current flows through the PTC thermistor, the temperature of the PTC thermistor increases. Since the PTC thermistor has a non-linear characteristic, the resistance value hardly increases until the temperature rises to a certain temperature. However, when the temperature reaches a certain temperature, the resistance value increases abruptly and current hardly flows. Therefore, by selecting and employing a PTC thermistor whose resistance value starts to increase suddenly at the current value at which the current limit is to be applied, the current limit can be applied without monitoring the current value.

  Next, the specific configuration and operation of the present embodiment will be described with reference to FIG. First, a description will be given of a case where the lock current flowing through the drain pump 10 is limited when the DC low-voltage power source drain pump 10 is prevented from rotating due to foreign matter and cannot rotate.

  The rotation of the DC low-voltage power source drain pump 10 is controlled by the control circuit 40 that controls the transistor 41 to be turned on and off. The transistor 41 may be a field effect transistor or a relay as long as it can be turned on / off by the control circuit 40. A PTC thermistor as a current limiting means 30 is provided between the power supply circuit 20 and the transistor 41. The PTC thermistor has a non-linear relationship between temperature and resistance, and is at a certain temperature, that is, a certain current. The current can be limited by the value. Select and use a PTC thermistor in which the current value of the PTC thermistor is a current when a liquid having an assumed viscosity flows to the DC low pressure power source drain pump 10, that is, a steady current or more and less than a lock current. As a result, the power supply circuit can be made smaller. For example, when the steady-state current of the DC low-voltage power source drain pump 10 is 200 mA, the lock current is 1000 mA, the current consumption of the other load 50 is 50 mA, and the current consumption of the control circuit 40 is 100 mA, the total current of the power supply circuit 20 is 1150 mA is required. However, if it is not necessary to continue the flow of the lock current and 300 mA obtained by adding 100 mA to the steady current is sufficient, the power supply circuit 20 having a total current of 450 mA may be used.

  In the case where the PTC thermistor (current limiting means 30) is not provided as in the prior art, the total current when the lock current flows is 1150 mA. Therefore, in the power supply circuit 20 with a total current of 450 mA, Abnormal heat generation and failure of electronic parts occur.

  Since the resistance value of the PTC thermistor (current limiting means 30) changes with temperature, it is necessary to always take into account the minimum operating ambient temperature and the limiting current value at the maximum operating ambient temperature. For example, assuming that a PTC thermistor with a minimum operating ambient temperature of 10 ° C, a current value that is limited at that time is 400 mA, and a maximum operating ambient temperature of 60 ° C and a current value that is limited at that time is 300 mA, is assumed. It can be limited by any current value of 300 mA to 400 mA under the operating temperature conditions.

  If the PTC thermistor having the above-described characteristics is provided, even if the DC low-pressure power drain pump 10 is locked, a current limit of 300 mA to 400 mA is applied, so that the power supply circuit 20 having a total current of 550 mA can be used. Therefore, when the power supply circuit 20 is a switching power supply, the current capacity and size of the switching transformer can be reduced, and the capacitance and size of the smoothing electrolytic capacitor formed in the switching power supply circuit can be reduced. Even when an off-the-shelf power supply device is used, one having a small current capacity and size can be used.

  The current limiting means 30 is not limited to the PTC thermistor described above, and it is possible to similarly limit the lock current even if a fuse is used. However, when a fuse is used, when a certain current flows, the permissible body is melted to interrupt the current. For this reason, even after removing the factor that hinders the rotation of the drain pump 10 after the permissible body has melted, it is not possible to flow current to the drain pump 10 without replacing the fuse. The drain pump 10 cannot be rotated. Therefore, it is necessary to replace the fuse every time the current is limited. On the other hand, if the PTC thermistor described above is adopted as the current limiting means 30, even if the current is limited, the factor that prevents the rotation of the drain pump 10 is removed so that the lock current does not flow. If the temperature of the PTC thermistor starts to drop and falls below the temperature at which the resistance value starts to increase suddenly, the DC low-voltage power source drain pump 10 can be rotated again without replacement like a fuse.

Next, an operation example when an arbitrary portion where current flows to the DC low-voltage power source type drain pump 10 is short-circuited to a different potential will be described with reference to FIG.
If any point where current flows to the DC low-voltage power source drain pump 10 is short-circuited to a different potential, an excessive short-circuit current flows, causing the power supply circuit 20 to stop functioning, abnormal heating or failure of electronic components. Occur. However, in this embodiment, if the short-circuited portion is an arbitrary portion between the PTC thermistor (current limiting means 30) and the drain pump 10, the short-circuit current flows only up to the current limit value of the PTC thermistor. For this reason, it is possible to obtain a function capable of preventing the function stop of the power supply circuit 20 and the abnormal heat generation and failure of the electronic component.

  If the current limiting means 30 is a fuse instead of a PTC thermistor, the short circuit current can be limited, but as described above, the cause of the short circuit is removed unless the fusible fuse is replaced. However, since the current to the drain pump 10 cannot flow, the drain pump 10 cannot be rotated. In this embodiment, since the PTC thermistor is used as the current limiting means 30, even if the current is limited, the temperature of the PTC thermistor starts to decrease and the resistance value starts to increase rapidly by removing the cause of the short circuit. When the temperature falls, the drain pump 10 can be driven again. Therefore, there is no need to replace the fuse like a fuse.

  By adopting the configuration of the present embodiment described above, even when a short circuit occurs at any point between the transistor 41 and the current limiting unit 30 and between the other load 50 and the current limiting unit 30, current limitation is applied. Can do. However, when a short circuit occurs at any point between the transistor 41 and the drain pump 10 or when a lock current flows through the drain pump 10, the current to the other load 50 is also limited. Will end up.

As described above, when a lock current flows through the drain pump 10, it is not necessary to limit the current with respect to the other load 50 connected in parallel to the drain pump 10 with respect to the power supply circuit 20. A configuration example of the electric circuit will be described with reference to FIG.
In FIG. 2, 30a, 30b, 30c, 30d, 30e, 30f are current limiting means (for example, PTC thermistors). By using any one of current limiting means 30a to 30f shown in FIG. 2 or a combination of a plurality of current limiting means, the current to other loads 50 can be configured not to be limited.

For example, current limiting means 30a provided in a circuit common to the drain pump 10 and the other load 50, and current limiting means 30b provided in a circuit dedicated to the drain pump in which the drain pump 10 is installed. When the current limiting means 30b is a PTC thermistor that is limited at 300 mA and the current limiting means 30a is a PTC thermistor that is limited at 500 mA, The lock current can be limited to 300 mA. Since the common circuit between the other load 50 and the power supply circuit 20 includes a PTC thermistor (current limiting means 30a) that is limited at 500 mA, the other load provided in a circuit dedicated to the other load. If the current consumption of 50 is 200 mA or less, the driving of the other load 50 can be continued. In addition, even when a short circuit occurs at an arbitrary position between the current limiting means 30b and the drain pump 10, as long as the lock current flows as described above, the current consumption of the other load 50 is 200 mA or less. The load 50 can be driven.

Note that the current to the current limiting means 30f provided in a common circuit to said other load 50 and the drain pump 10 instead of the limiting means 30a, the said drain pump 10 in place of the current limiting means 30b transistors The same effect can be obtained even if the current limiting means 30d provided between the terminal 41 and 41 is employed.

The current limiting means 30c or 30e is for allowing the operation of the drain pump 10 to be continued even when a short circuit occurs in a dedicated circuit for the other load 50. That is, if either the current limiting means 30c or 30e is provided and a PTC thermistor limited at 200 mA is used as the current limiting means, even if a short circuit occurs in a dedicated circuit to another load 50, the drain pump A current of 300 mA or less can be passed through 10, and the operation of the drain pump 10 can be continued.
Note that at least one of the current limiting means 30c and 30f may be provided.

As described above, according to this embodiment, the lock current does not continue to flow through the drain pump 10 of the DC low-voltage power supply type, and it is only necessary to consider the lock current for the time until the current limiting means 30 operates. The power supply circuit 20 can be reduced in size, and as a result, the weight and cost can be reduced.
Further, according to the present embodiment, even when an arbitrary part of the circuit after the current limiting means 30 through which the current to the drain pump 10 flows is short-circuited with a different potential, the time until the current limiting means works. Since the short-circuit current only needs to be taken into consideration, it is possible to prevent the power supply circuit from stopping functioning due to the continuous short-circuit current and the occurrence of abnormal heat generation and failure of the electronic components.

10: drain pump,
20: power circuit,
30, 30a-30f: current limiting means (PTC thermistor),
40: control circuit,
41: transistor,
50: Other load.

Claims (3)

In an air conditioner including a drain pump and a power supply circuit for driving the drain pump,
While using a DC low-voltage power supply type as the drain pump,
A switching element is provided in a circuit dedicated to the drain pump in which the drain pump is installed, and the drain pump is connected to the power supply circuit via the single switching element, and the switching element is turned on. The drain pump is configured to rotate, and
With another load connected in parallel with the drain pump to the power supply circuit,
A current limiting means is provided in a circuit dedicated to the drain pump in which the drain pump is installed between the DC low-voltage power source type drain pump and the power supply circuit . a PTC thermistor whose resistance value increases, the PTC thermistor, after limiting the current, at a current limit value or less of the current, characterized by the Turkey is configured such that current limitation is canceled Air conditioner. Air conditioner, characterized in that there is provided a current limiting means in a common circuit in the air conditioner according to the prior SL said other load drain pump to claim 1. The air conditioner according to claim 1 or 2 , wherein a current limiting means is also provided in a circuit dedicated to the other load in which the other load is installed.

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