JPH01174842A - Safety device for prevention of overheating of heater in air conditioner - Google Patents

Abstract

PURPOSE:To enable overheating of a heater for auxiliary heating to be appropriately prevented without any complicated control, by stopping energization of the heater in an air conditioner when the current detected by a current detecting means for detecting an operating current of a refrigerant compressor exceeds a predetermined reference current value. CONSTITUTION:Where a heater 7 is energized, an operating current IC of a compressor 5 is detected by a current transformer 11 provided as a current- detecting means for the compressor, and is compared with a reference current value I0 for prevention of overheating of the heater, which is preset in a memory 15 in a microcomputer controller 2. When the detected current IC exceeds the reference current value I0, that is, when the quantity of air blown by an interior fan 2 on the side of a heat exchanger 1 for controlling the operation of a condenser is lowered in a refrigerating cycle with the results of a reduction in heat exchange quantity, an increase in condensing pressure and an increase in the operating current of the compressor, an output to a heater relay coil 18 is turned OFF, and a heater relay contact is opened to stop energization of the heater 7, thereby preventing abnormal overheating or the like.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention provides a safety device for preventing heater overheating of an air conditioner;
In particular, the indoor heat exchanger, the outdoor heat exchanger, and the compressor are connected via a refrigerant flow path so that the indoor heat exchanger acts as a condenser, and the indoor heat exchanger includes: The present invention relates to a safety device for preventing heater overheating of an air conditioner that includes a heater for auxiliary heating, an indoor heat exchanger, and an indoor fan that blows air heated by the heater indoors.

[Prior art] In conventional air conditioners of this type, when the outside temperature is relatively low, such as during winter or severe cold, the temperature of the indoor heat exchanger is reduced.
In some cases, the 11A capacity decreases and comfortable heating cannot be performed, so in order to compensate for this heating capacity, the indoor heat exchanger is equipped with a heater for auxiliary heating of the room.

By the way, if this type of heater is installed, if a failure occurs in the fan motor and the indoor fan stops driving, or if the drive rotational speed of the indoor fan decreases, the heat generated by the heater may There were problems such as the casing and other surrounding parts being overheated and deformed/damaged, and in the case of refrigerant heaters, the overheating could cause the refrigerant to decompose or change in quality. .

For this reason, conventionally, safety devices such as an overheat protector and a temperature fuse have been provided to prevent the heater from overheating. As an example, Figure 7 shows the
8-15824 is a schematic structural diagram of a main part of an indoor heat exchanger (indoor coil) equipped with a conventional safety device.

FIG. 8 is a detailed partially cutaway structural diagram of this safety device. In Figure 7, 5! 52 is a heat exchanger tube passing through each fin 51; 53 is an electric heater inserted into and installed inside the heat exchanger tube 52; 54 is a heat exchanger tube 52 adjacent to the heat exchanger tube 52 inside the heater 53; This is a safety device that is inserted through the device.

As shown in FIG. 8, in this safety device 54, temperature fuses 56 and 57 having different melting temperatures are connected in series in a small-diameter glass tube 55, and heat-resistant electric wires are drawn out from both ends of the glass tube 55. It is composed of As a result, the heat generation temperature of the electric heater 53 is adjusted to the temperature of each fin 51. The heat is appropriately transmitted to the safety device 54 via the heat transfer tube 52. In normal cases, the temperature fuse 56
．． In addition to 57, in order to detect the surface temperature of the heater 53 and stop energizing the heater 53, an overheat protector made of bimetal or the like is attached, and the heater 53 is stopped before each temperature fuse 56, 57 is blown. Configured to stop.

[Problem that the invention seeks to solve]

However, in the conventional example with the above configuration,
When the heating capacity of the heater increases (for example, l100
W-h), the heat capacity of the heater itself has increased, and even if the overheat protector is activated, the temperature fuse will reach its fusing temperature and blow out at the same time or almost at the same time. The temperature fuse will have to be replaced with a new one. However, such replacement work is extremely troublesome in terms of operation management of the air conditioner, and furthermore, makes the existence of the desuperheater meaningless.

In other words, although the operating temperature of the desuperheater is set to a relatively lower temperature than that of the temperature fuse, since the temperature is used to detect the surface temperature of the heater, the desuperheater When the detected temperature is lower than the temperature of the heater itself and the temperature of the heater itself rises, there is a time lag before that temperature is detected by the overheat protector, which prevents overheating. The response of the instrument is poor. As a result, by the time the temperature reaches a level sufficient to activate the overheat protector, the temperature of the heater itself has already reached the melting temperature of the temperature fuse or a temperature close to it.

In addition, under normal circumstances, the temperature at which the temperature fuse blows is set quite high, and as mentioned above, the overheat protector operates and the temperature fuse blows, even if the heater drive is stopped. In the case of a refrigerant heater, the refrigerant is subject to abnormal overheating, and deformation and damage to the surrounding components and decomposition and deterioration of the refrigerant can be sufficiently avoided. I couldn't do it.

This invention has been made in view of the problems of the conventional examples as described above, and is a method of this type that can accurately prevent overheating of an auxiliary heating heater without any troublesome management. The purpose is to provide safety equipment.

[Means for solving problems]

Therefore, in the present invention, as shown in FIG. 1, which is a block diagram of the configuration of the safety device according to the present invention, a current detection means 11 for detecting the operating current of the refrigerant compressor is provided, and the current value is set to a predetermined value. The above object is achieved by comprising a heater energization control means 12 that outputs a signal to stop energization to the auxiliary heating heater of the air conditioner when the reference current value exceeds the reference current value. be.

[Effect]

In other words, when using beat pump heating, when the auxiliary heater is also energized for heating, if the indoor fan stops driving due to a failure in the fan motor, etc., or the indoor fan speed decreases, condensation may occur. The pressure in the indoor heat exchanger that acts as a heat exchanger increases, and the operating current of the compressor increases. Therefore, by detecting this current value using the current detecting means of the present invention, it is possible to detect an overheating state of the heater, so that it is possible to stop energizing the heater and prevent the heater from overheating.

〔Example〕

The present invention will be explained below based on examples. FIG. 2 shows a schematic configuration diagram of an embodiment of an air conditioner equipped with the safety device shown in FIG.

(Configuration) 1 is an indoor heat exchanger, 2 is a cross-flow indoor fan, 3 is an outdoor heat exchanger, 4 is an outdoor fan, 5 is a refrigerant compressor, 6 is n1 indoor heat a four-way switching valve for connecting the exchanger 1 and the outdoor heat exchanger 3 to the compressor 5;
is an auxiliary heating heater. 8 is a casing in which the indoor heat exchanger 1, the indoor fan 2, and the heater 7 are housed, and within this casing 8 are a drain pan 9,
A heated air outlet [11o] is provided at the bottom of the casing.

FIG. 3 is an embodiment of an electric circuit diagram of an air conditioner according to the present invention. In the figure, reference numeral 12 denotes a microcomputer (abbreviated as microcomputer) control device, and an input circuit 13. which receives the signal of the current transformer 11 for detecting the operating current of the compressor 5. CPU14, memory 15. It consists of an output circuit 16 and the like. The output circuit 16 is connected to a heater relay coil (Xi) 18 corresponding to a heater relay contact (XI) 17 that turns on and off the heater 7 . Further, a primary coil of a transformer 20 is connected between both poles of the AC power source 19, and the secondary coil of the transformer 20 is configured to apply voltage to each member of the microcomputer control device 12.

(Function) Next, the function of this embodiment will be explained in the microcomputer control device 1 shown in FIG.
This will be explained using the control sequence flowchart of No. 2.

First, in step 30, it is determined whether the auxiliary heating heater 7 is energized. Next, heater connoisseurs? In the case of "state, in step 31, the operating current of the compressor 5 is detected by the current transformer 11 which is the current detection means of the compressor 5, and in step 32, the operating current of the compressor 5 is preset in the memory 15 in the microcomputer control device 12. Compressor 5 to prevent heater overheating
Reference current value of■. Which comparison to make. If the detection current ■.

becomes the reference current value 10 or more, that is, in the refrigeration cycle, the indoor fan 2 on the side of the heat exchanger (indoor heat exchanger, since this is a heating cycle) that controls the action of the condenser Air volume decreases (fan speed control decreases,
If the heat exchange amount decreases, the condensing pressure increases, and the compressor operating current increases, the output to the heater relay coil 18 is turned off in step 33. Then, the heater relay contact 17 is opened to stop power supply to the heater 7, thereby preventing abnormal overheating.

(Other Embodiments) In the above embodiments, the heater energization was controlled to be fully closed or fully opened, but for example, FIG. 5 shows another embodiment of the electric circuit diagram (the If a plurality of auxiliary heating heaters 7a and 7b are provided, as shown in FIG. 3 (the same (equivalent) components are indicated by the same reference numerals), each heater relay contact (Xi) is provided for each of them.
17° (X2) 22, each relay coil (xl) 1
8, (X2) 21 is connected to the output circuit 16.

The control sequence of the microcomputer control device 12 in the circuit configuration as described above will be explained with reference to the flowchart shown in FIG.

First, in step 41, it is determined whether or not the heater 7 is energized. When the heater is energized, the compressor operating current ■ゎ is detected in step 42, and compared with the reference current II in step 43. If IC≧■, one of the heater relay coils (X2) 21 Then, in step 44, the heater river relay contact 22 is opened to stop energizing the other heater 7b. moreover,
In step 45, the compressor operating current 1c is detected again, and in step 46, another reference current 12 (12>I+
), and if ■. If ≦■2, power supply to the other heater 7a is stopped to prevent abnormal overheating or the like.

〔Effect of the invention〕

As explained above, according to the present invention, when an abnormality in the indoor fan motor or a sudden decrease in air volume occurs, the increase in the operating current of the compressor that immediately appears is utilized, and this current value is It is now possible to prevent heating by turning off the power to the auxiliary heating heater.

This not only makes it possible to reliably avoid deformation and damage to surrounding parts due to heater overheating, and decomposition and deterioration of the refrigerant in the case of refrigerant heaters, but also eliminates the need to install an overheat protector or temperature fuse as in the past. In addition, even if such overheat protectors and temperature fuses are installed, they should be used as a final safety measure, and the temperature fuses will be blown each time overheating occurs and must be replaced when restarting. You can prevent troublesome situations such as
Management has become easier.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of a safety device according to the present invention;
FIG. 2 is a schematic configuration diagram of an embodiment of an air conditioner equipped with this safety device, and FIG. 3 is an electrical circuit diagram of an embodiment of the air conditioner.
FIG. 4 is a control sequence flowchart of FIG. 3, FIG. 5 is an electric circuit diagram showing another embodiment, FIG. 6 is a control sequence flowchart thereof, and FIG. 7 is a conventional indoor heat exchanger. FIG. 8 is a schematic structural diagram of main parts of an example of the present invention, and FIG. 8 is a partially cutaway structural diagram of the safety device. 1------Indoor heat exchanger 2------Indoor fan 3---Outdoor heat exchanger 5...Refrigerant compressor 7.7a, 7b.'' ...Heating auxiliary heating heater TC・
...Compressor operating current 1o, I+, 12-=reference current Note that in each figure, the same (equivalent) components are represented by the same symbols.

Claims (2)

[Claims] (1) Connect the indoor heat exchanger, outdoor heat exchanger, and refrigerant compressor through a refrigerant circuit so that the indoor heat exchanger functions as a condenser, and use the indoor heat exchanger for auxiliary heating. An air conditioner equipped with an indoor heater and an indoor fan that blows the heated air indoors, comprising: current detection means for detecting an operating current of the refrigerant compressor; and an operation of the compressor detected by the detection means. 1. A safety device for preventing heater overheating of an air conditioner, comprising: a control means for stopping energization to the auxiliary heating heater when the current exceeds a predetermined reference current value. (2) In the air conditioner having a plurality of auxiliary heating heaters, a relay or the like is connected to each heater, and the power supply to each heater is stopped in stages according to the operating current of the refrigerant compressor. 2. A safety device for preventing overheating of a heater of an air conditioner according to claim 1, further comprising a control means for controlling.