JP2536354B2 - Refrigerator protection device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protection device for a refrigerating device which controls a discharge pipe temperature, and more particularly to a burnout prevention measure for a compressor caused by removal of a discharge pipe temperature sensor.

[0002]

2. Description of the Related Art Conventionally, for example, Japanese Patent Publication No. 59-1294
As disclosed in Japanese Unexamined Patent Publication No. 2 (1998), as an operation control device for a refrigeration system including a refrigerant circuit in which a compressor, a condenser, an electric expansion valve, and an evaporator are sequentially connected, based on the evaporation temperature and the condensation temperature of the refrigerant circuit. A constant capacity compressor is used by calculating the optimum temperature of the discharge pipe temperature of the compressor that gives the maximum refrigeration effect and controlling the opening of the electric expansion valve with this optimum temperature as the control target value of the discharge pipe temperature. However, it is a known technique to maintain good refrigerating capacity and operating efficiency of the refrigerating apparatus.

[0003]

In the refrigeration system, the discharge pipe temperature sensor attached to the discharge pipe of the compressor is usually used to operate the protective device, and is often used due to lack of refrigerant. When the internal temperature of the compressor rises excessively, the protection device is activated by the signal of the discharge pipe temperature sensor to stop the operation of the refrigeration system.

However, the discharge pipe temperature sensor may come off from the discharge pipe due to an installation error or the like during installation of the refrigeration system or an accident during operation. In such a case, the discharge pipe temperature sensor discharges even if the internal temperature of the compressor rises excessively. Since the detected value of the pipe temperature sensor hardly changes, the protective device does not operate, and as a result, there is a risk of accidents such as burnout of the compressor.

In particular, as in the above-mentioned publication, in the case where the discharge pipe temperature of the compressor is controlled to the target value by the opening of the electric expansion valve, the opening of the electric expansion valve is changed when the value detected by the discharge pipe temperature sensor is low. Since the control is performed in the direction of squeezing, if the operation is continued as it is, there is a problem that the refrigerant of the compressor is gradually reduced, and the risk of burning the compressor immediately becomes extremely high.

The present invention has been made in view of the above problems, and an object of the present invention is to prevent burnout of a compressor by providing a means for surely detecting that the discharge pipe temperature sensor is disengaged from the discharge pipe. To prevent it.

[0007]

In order to achieve the above object, the means taken by the invention of claim 1 is, as shown in FIG. 1 (not including a dotted line portion), a compressor (1), a heat source side. A refrigeration system provided with a refrigerant circuit (9) in which a heat exchanger (3), an electric expansion valve (5), and a use side heat exchanger (6) are sequentially connected is assumed.

A discharge pipe temperature sensor (Th2), which is attached to the discharge pipe (8d) of the compressor (1) and detects the discharge pipe temperature, serves as a protection device for the refrigeration system, and the discharge pipe temperature sensor (Th2). ), And when the temperature of the discharge pipe reaches or exceeds a predetermined temperature, a protection means (11) is provided which operates to stop the operation of the refrigeration system, and further, an outside air temperature detecting means (Tha) for detecting the outside air temperature. And a time-measuring means (12) for measuring an elapsed time after the compressor (1) is activated, and an output of the time-measuring means (12), when the predetermined time has elapsed after the activation of the compressor (1), Discharge pipe temperature sensor (Th
When the detected value of 2) is lower than the temperature obtained by adding a constant value to the outside air temperature detected by the outside air temperature detecting means (Tha),
An abnormality processing means (53) for abnormally stopping the refrigeration system is provided.

According to the invention of claim 2, in the invention of claim 1, as shown by the broken line portion in FIG. 1, the optimum means is selected according to the condensation temperature, the evaporation temperature, etc. of the refrigerant circuit (9). The optimum temperature calculating means (51) for calculating the optimum temperature of the discharge refrigerant temperature which gives a refrigerating effect, and the discharge pipe temperature sensor (T
an opening control means (52) for controlling the opening of the electric expansion valve (5) so that the discharge pipe temperature converges to the optimum temperature calculated by the optimum temperature calculation means (51) by receiving the output of h2). Is provided.

[0010]

With the above structure, in the invention of claim 1, when the discharge pipe temperature detected by the discharge pipe temperature sensor (Th2) becomes a predetermined temperature or more during the operation of the refrigeration system, the protection means (11) is provided.
As a result, the refrigeration system is abnormally stopped and the compressor (1) is protected, but the discharge pipe temperature sensor (Th2) is changed to the discharge pipe (8d).
If it has fallen off, the detected value of the discharge pipe temperature sensor (Th2) becomes a value different from the actual discharge temperature. In particular, the opening degree of the electric expansion valve (5) may change depending on the operating state, and the amount of refrigerant circulation may decrease due to throttling. In such a state, the compressor (1) is overheated. Even if the temperature of the discharge pipe is excessively increased, the protection device (11) does not operate, which may lead to an accident such as burnout of the compressor (1).

When the discharge pipe temperature sensor (Th2) is dropped from the discharge pipe (8d), the temperature detected by the discharge pipe temperature sensor (Th2) approaches the outside air temperature without limit. If the value detected by the discharge pipe temperature sensor (Th2) has not risen above the outside air temperature by a certain value after the lapse of a predetermined time after startup, it is highly possible that the discharge pipe temperature sensor (Th2) has fallen off. . Therefore, the air conditioner is abnormally stopped by the abnormality processing means (53), so that the burnout of the compressor (1) is prevented in advance.

According to a second aspect of the present invention, in the first aspect of the present invention, the optimum temperature calculating means (51) calculates the optimum temperature of the discharge pipe temperature which gives the optimum refrigerating effect based on the evaporation temperature, the condensation temperature and the like. When the opening control means (52) controls the opening of the electric expansion valve (5) so that the discharge pipe temperature converges to this optimum temperature, the discharge pipe temperature sensor (Th2) falls off. If the detected value is lower than the actual discharge pipe temperature, the apparent discharge pipe temperature becomes smaller than the control target value, so the opening degree of the electric expansion valve (5) is closed. Therefore, if the operation is continued as it is, there is a high possibility that the compressor (1) will be overheated and burned out in a short time, and the compressor (1) may be burnt out. Due to the action of the described invention, accidents such as burnout of the compressor (1) can be prevented in advance.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 2 shows a refrigerant piping system of an air conditioner to which the present invention is applied, which is a so-called separate type in which one indoor unit (B) is connected to one outdoor unit (A). is there. The outdoor unit (A) includes a compressor (1), a four-way switching valve (2) that switches as shown by a solid line in the figure during a cooling operation and a broken line in the figure as a heating operation, and as a condenser during a cooling operation. The outdoor heat exchanger (3), which is a heat source side heat exchanger that functions as an evaporator during heating operation, and a decompression unit (20) for decompressing the refrigerant.
And an accumulator (7) for removing the liquid refrigerant in the suction refrigerant, which is interposed in the suction pipe of the compressor (1) and is arranged as a main device. Further, the indoor unit (B) is provided with an indoor heat exchanger (6) which is a utilization side heat exchanger that functions as an evaporator during cooling operation and as a condenser during heating operation. Each of the above equipment is a refrigerant pipe (8)
A refrigerant circuit (9) is constructed in which the refrigerant circuits (9) are sequentially connected to each other to generate heat transfer by circulating the refrigerant.

The pressure reducing section (20) is provided with a receiver (4) for storing the liquid refrigerant and an electric expansion valve (5) having a pressure reducing function and a flow rate adjusting function for the liquid refrigerant. The receiver (4) and the electric expansion valve (5) are arranged so that the electric expansion valve (5) communicates with the lower portion of the receiver (4), that is, the liquid portion. ) Auxiliary heat exchanger (3a)
Are arranged in series on the common path (8a). Then, between the outdoor end (P) of the receiver (4) upstream of the common path (8a) and the outdoor heat exchanger (3), the outdoor heat exchanger (3) goes to the receiver (4). Between the point (P) of the common path (8a) and the indoor heat exchanger (6) by the first inflow path (8b1) via the first check valve (D1) that allows only the circulation of the refrigerant. Is from the indoor heat exchanger (6) to the receiver (4)
To the electric expansion valve (5) on the common path (8a) while being connected to each other by the second inflow path (8b2) through the second check valve (D2) that allows only the circulation of the refrigerant to the From the electric expansion valve (5) to the indoor heat exchanger (6) between the side end (Q) and the point (R) between the second check valve (D2) and the indoor heat exchanger (6). Through the third check valve (D3) allowing only the circulation of the refrigerant, the first outlet path (8c1) allows the point (Q) of the common path (8a) and the first check valve (D1)- A fourth check valve (D4) which allows only the flow of the refrigerant from the electric expansion valve (5) to the outdoor heat exchanger (3) is provided between the outdoor heat exchanger (3) and the point (S). 2nd outflow channel (8c2)
Are respectively connected by.

Further, a capillary tube (C) is provided between the upstream point (P) and the outflow point (Q) of the receiver (4) to prevent liquid sealing. Bypass (8f)
Is provided, the liquid sealing prevention bypass passage (8f) prevents liquid sealing when the compressor (1) is stopped, and the gas refrigerant flows from the upper portion of the receiver (4) to the first outflow passage (8c1). ) It is designed to be able to move to the side. The degree of decompression of the capillary tube (C) is set to be sufficiently larger than that of the electric expansion valve (5), and the function of adjusting the refrigerant flow rate by the electric expansion valve (5) during normal operation is improved. It is designed to be maintainable.

Incidentally, (F1) to (F4) are filters for removing dust in the refrigerant, and (ER) is a silencer for reducing the operation noise of the compressor (1).

Further, the air conditioner is provided with sensors, (Th2) is arranged in the discharge pipe, a discharge pipe temperature sensor for detecting the discharge pipe temperature T2, and (Tha) of the outdoor unit (A). An outdoor intake sensor (Thc), which is arranged at the air intake port and detects the intake air temperature Ta that is the outside air temperature, is arranged in the outdoor heat exchanger (3) and becomes the condensation temperature during the cooling operation and the evaporation temperature during the heating operation. Outside heat exchange temperature Tc
(Thr) is an indoor heat exchanger (6) that is located at the air intake port of the indoor unit (B) and that detects the intake air temperature Tr that is the indoor temperature. ), The internal heat exchange sensor Te detects the internal heat exchange temperature Te which becomes the evaporation temperature during the cooling operation and becomes the condensation temperature during the heating operation, and (HPS) is turned on by the excessive increase of the high-pressure side pressure, and the protection device described later. A high pressure switch for activating (11), and (LPS) is a low pressure switch for activating the protection device (11) which is turned on due to an excessive decrease in pressure on the low pressure side. Each of the sensors is connected to a controller (10) that controls the operation of the air conditioner, and the controller (10) controls the operation of the air conditioner according to the signals of the sensors. It is designed to do.

Further, in the controller (10),
A protective device (11) as a protection means that operates when an abnormality occurs during operation of the air conditioner to abnormally stop the air conditioner, and a timer (12) as a time measuring means for measuring time are built-in. Has been done. Although not shown, the protection device (11) also receives signals from the discharge pipe temperature sensor (Th2) in addition to the pressure switches (HPS) and (LPS), and the discharge pipe temperature T2 is predetermined. When the temperature exceeds the temperature, the protection device (11) is activated to abnormally stop the air conditioner and prevent accidents such as burnout of the compressor (1).

FIG. 3 shows a state in which the discharge pipe temperature sensor (Th2) is attached to the discharge pipe. The discharge pipe temperature sensor (Th2) is shown in FIG.
Is a temperature-sensitive tube mounting pipe (2) brazed to the discharge pipe (8d).
1), the discharge pipe heat insulating material (22) is attached from the outside, and the discharge pipe temperature sensor (Th2) is fixed. Note that (23) is a sensor mounting spring member.

In the refrigerant circuit (9), during the cooling operation, the liquid refrigerant condensed and liquefied in the outdoor heat exchanger (3) flows in from the first inflow path (8b1) and passes through the first check valve (D1). After being stored in the receiver (4) and decompressed by the electric expansion valve (5), it is evaporated in the indoor heat exchanger (6) through the first outflow passage (8c1) and returns to the compressor (1). While circulating,
During the heating operation, the liquid refrigerant condensed and liquefied in the indoor heat exchanger (6) flows in from the second inflow passage (8b2), is stored in the receiver (4) via the second check valve (D2), After the pressure is reduced by the electric expansion valve (5), it is circulated through the second outflow passage (8c2) to evaporate in the outdoor heat exchanger (3) and return to the compressor (1).

Here, the control contents of the controller (10) will be described. FIG. 4 shows the controller (1
0) shows the control contents during the cooling operation in step S).
At T1, the evaporation temperature Te detected by the internal heat exchange sensor (The) and the condensation temperature T detected by the external heat exchange sensor (Thc)
c and the discharge pipe temperature T2 detected by the discharge pipe temperature sensor (Th2) are input respectively, and in step ST2, the following (1)
Formula Tk = 4-1.13Te + 1.72Tc
Based on (1), the optimum temperature Tk, which is the discharge pipe temperature that gives the optimum refrigeration effect EER, is calculated.

Then, in step ST3, the expression ΔT2 =
After calculating the temperature difference ΔT2 between the discharge pipe temperature T2 and the optimum temperature Tk based on T2-Tk, in step ST4, | ΔT
2 | ≦ 5, that is, the discharge pipe temperature T2 is the optimum temperature Tk
It is determined whether or not it has converged within a certain range above and below, and until it converges, the process proceeds to step ST5 and whether or not ΔT2 is positive,
That is, it is determined whether or not the discharge pipe temperature T2 is higher than the optimum temperature Tk.
At T6, the electric expansion valve (5) is controlled to open to the middle level, while if the discharge pipe temperature T2 is lower, step ST7.
Then, the opening degree of the electric expansion valve (5) is controlled so as to be closed to an intermediate level.

On the other hand, in the determination in step ST4, | Δ
When T2 | ≦ 5 and the discharge pipe temperature T2 converges within a certain range above and below the optimum temperature Tk, the process proceeds to step ST8, and although not described in detail, the opening degree of the electric expansion valve (5) is finely adjusted. Perform fuzzy control.

In the above flow, the optimum temperature calculating means (5) according to the invention of claim 2 is controlled by the control of step ST2.
1) is configured, and the opening degree control means (52) according to the invention of Claim 2 is configured by the control of steps ST4 to ST8.

Next, the content of the dropout detection control of the discharge pipe temperature sensor (Th2) will be described based on the flowchart of FIG. First, in step SS1, it is determined whether or not 5 minutes have passed since the start of the air conditioner, and until 5 minutes have elapsed, the process proceeds to step SS10 to perform normal operation.
Then, when 5 minutes have elapsed after the start-up, steps SS2 to
At SS5, check if the defrost operation is not in progress, T2-To2
≤5 (° C) (where T2 is the discharge pipe temperature when 5 minutes have passed after startup, To2 is the discharge pipe temperature at startup), whether T2 <55 (° C), T2 < Whether or not Ta + 10 is determined, and if at least one of the determination results is NO, the process proceeds to step SS10 and normal operation is performed, while if the determination results in each of steps SS2-SS5 are YES, step Proceeding to SS6, the number of detections Fg counted by a counter (not shown) is integrated. Then, in step SS7, it is determined whether or not Fg ≧ 6, and until Fg ≧ 6, the process proceeds to step SS8, the thermo-off operation is performed for a certain period of time, and the above-described drop detection control is repeated. When Fg ≧ 6, that is, 6
After each retry, the above steps SS2-
When the condition of SS5 is satisfied, it is determined that the discharge pipe temperature sensor (Th2) has fallen out of the discharge pipe (8d) for the first time, and the process proceeds to step SS9 to perform an abnormal process of abnormally stopping the air conditioner. .

In the above flow, the abnormality processing means (53) according to the invention of claim 1 is constituted by the control from step SS5 to step SS9.

Therefore, in the above embodiment, when the discharge pipe temperature T2 detected by the discharge pipe temperature sensor (Th2) becomes a predetermined temperature or higher during the operation of the air conditioner, the protective device () provided in the controller (10) ( 11) operates, the air conditioner is abnormally stopped, and the compressor (1) is protected. However, the discharge pipe temperature sensor (Th2) is
If it is dropped from d), the detected value T2 of the discharge pipe temperature sensor (Th2) becomes a value different from the actual discharge temperature (a value corresponding to the outside air temperature), so the compressor (1) overheats. Even if the discharge pipe temperature rises excessively, the detected value T2 is low. Therefore, the protective device (11) does not operate and may cause an accident such as burnout of the compressor (1). However, in the above-described embodiment, the discharge pipe temperature sensor (Th2 is determined by the determination in steps SS2 to SS5). ) Is detected, the air conditioner is abnormally stopped by the abnormality processing means (53), so that the burnout of the compressor (1) is prevented in advance.

Here, in the control of step SS2, it is determined whether or not the defrosting operation is being performed, because the refrigerant circulation amount becomes extremely large during the defrosting operation, so that the discharge pipe temperature T
This is to prevent erroneous detection in which it is determined that the discharge pipe temperature sensor (Th2) is normally attached but is dropped in the determination in a later step, because a state where 2 is extremely low may occur.

Further, in the control of step SS3, T2-T
Whether or not o2 ≦ 5 (° C.) is determined is that, after 5 minutes have passed since the start-up, the discharge pipe temperature T2 at the time of start-up should increase from the discharge pipe temperature To2 of about 10 ° C. under normal conditions. If T2−To2 ≦ 5 (° C.), it is extremely likely that the discharge pipe temperature sensor (Th2) has fallen off.

In the control of step SS4, T2 <5
Whether or not the temperature is 5 (° C) is determined because it is unlikely that the discharge pipe temperature T2 is usually lower than 55 ° C after the compressor (1) is started. Therefore, when T2 <55 (° C), the discharge is performed. This is because it is very likely that the tube temperature sensor (Th2) has fallen off.

Further, the control of step SS5 corresponds to the invention of claim 1, and the discharge pipe temperature sensor (Th2) is determined by determining whether T2 <Ta + 10.
If the temperature drops from the discharge pipe (8d), the detected temperature approaches the outside air temperature Ta infinitely, and if the temperature is not higher than the outside air temperature by 10 ° C or more after about 5 minutes, the discharge pipe temperature is This is a control for detecting that the possibility that the sensor (Th2) is missing is extremely high.

In particular, as in the above embodiment, the optimum temperature calculating means (51) calculates the optimum temperature Tk of the discharge pipe temperature T2 which gives the optimum refrigerating effect based on the evaporation temperature Te, the condensation temperature Tc and the like. When the opening control means (52) controls the opening of the electric expansion valve (5) so that the discharge pipe temperature T2 converges to the optimum temperature Tk, the discharge pipe temperature sensor (Th2) falls off. When the detected value T2 is lower than the actual discharge pipe temperature, ΔT2 becomes smaller than the actual value in the control flow of FIG. 4, and as a result, the opening of the electric expansion valve (5) is controlled by the control of step ST7. Will be closed. Therefore, if the operation is continued as it is, the refrigerant is rapidly reduced, and there is a high risk that the compressor (1) will be overheated and burned in a short time. Therefore, by applying the control for detecting the drop of the discharge pipe temperature sensor (Th2) to the system for performing such discharge pipe temperature control, a remarkable effect can be exhibited.

The method of calculating the optimum temperature Tk is not limited to the above embodiment, and it is also possible to perform a calculation such as correction with the outside air temperature Ta.

Further, in the above embodiment, in the control flow of FIG. 5, the abnormality process of step SS9 is performed only when the determination results of steps SS3 to SS5 are all YES, but the present invention is not limited to this. The present invention is not limited to this embodiment, but only one of the steps SS3 to SS5 may be determined, and if the result of the determination is YES, the process may proceed to step SS9.

[0036]

As described above, according to the invention of claim 1, the refrigeration provided with the refrigerant circuit in which the compressor, the heat source side heat exchanger, the electric expansion valve and the utilization side heat exchanger are sequentially connected. As an operation control device of the device, while the refrigeration system is in operation, when the discharge pipe temperature detected by the discharge pipe temperature sensor becomes equal to or higher than a predetermined temperature, a protection means for abnormally stopping the refrigeration system is provided,
When the value detected by the discharge pipe temperature sensor is lower than the temperature obtained by adding a constant value to the outside air temperature after the elapse of a predetermined time after the compressor is started, the operation of the refrigeration system is abnormally stopped. By reliably detecting the state, it is possible to prevent accidents such as burning due to an excessive rise in the internal temperature of the compressor.

According to the invention of claim 2, the invention of claim 1 is applied to a system having a system for controlling the opening of the electric expansion valve so that the discharge pipe temperature converges to its optimum temperature. There is a risk that the opening of the electric expansion valve will be closed when the temperature of the discharge pipe above the control becomes lower than the control target value, and the compressor will overheat and burn out in a short time due to the rapid decrease of the refrigerant. Even when the pressure is high, accidents such as burnout of the compressor can be prevented in advance, and therefore, the remarkable effect of the invention according to claim 1 can be exerted.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of the present invention.

FIG. 2 is a refrigerant piping system diagram of the air conditioning apparatus according to the embodiment.

FIG. 3 is an exploded perspective view showing how the discharge pipe temperature sensor is attached to the discharge pipe.

FIG. 4 is a flowchart showing the contents of discharge pipe temperature control.

FIG. 5 is a flowchart showing the details of dropout detection control of the discharge pipe temperature sensor.

[Explanation of symbols]

 1 Compressor 3 Outdoor Heat Exchanger (Heat Source Side Heat Exchanger) 5 Electric Expansion Valve 6 Indoor Heat Exchanger (Use Side Heat Exchanger) 9 Refrigerant Circuit 11 Protection Device (Protection Means) 12 Timer (Timekeeping Means) 51 Optimum Temperature Calculation means 52 Opening degree control means 53 Abnormality processing means Th2 Discharge pipe temperature sensor Tha Outdoor suction sensor (outside air temperature detection means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Takeo Ueno 1304 Kanaoka-machi, Sakai City, Osaka Prefecture Daikin Industrial Co., Ltd., Kanaoka Plant, Sakai Manufacturing Co., Ltd. (56) Reference JP-A-3-1061 (JP, A)

Claims (2)

(57) [Claims] 1. A compressor (1), a heat source side heat exchanger (3),
A refrigerating apparatus comprising a refrigerant circuit (9) in which an electric expansion valve (5) and a use side heat exchanger (6) are sequentially connected to each other, the refrigeration apparatus being attached to a discharge pipe (8d) of the compressor (1), A discharge pipe temperature sensor (Th2) for detecting the pipe temperature, and a protection means for receiving the output of the discharge pipe temperature sensor (Th2) and operating when the discharge pipe temperature reaches or exceeds a predetermined temperature to stop the operation of the refrigeration system. (11), the outside air temperature detecting means (Tha) for detecting the outside air temperature, and the time counting means (1) for measuring the elapsed time after the start of the compressor (1).
2) and the output of the time measuring means (12), the detected value of the discharge pipe temperature sensor (Th2) when a predetermined time has elapsed after the compressor (1) is started is the outside air temperature detecting means (Tha). A protection device for a refrigerating device, comprising: an abnormality processing means (53) for abnormally stopping the refrigerating device when the temperature is lower than a temperature obtained by adding a constant value to the outside air temperature detected in. In the protection apparatus of claim 2 according to claim 1 Symbol placement of the refrigeration apparatus, the optimum condensation temperature of the refrigerant circuit (9), depending on the evaporation temperature or the like, calculates the optimum temperature of the discharged refrigerant temperature giving refrigeration effect optimum The electric expansion valve (5) receives the outputs of the temperature calculating means (51) and the discharge pipe temperature sensor (Th2) so that the discharge pipe temperature converges to the optimum temperature calculated by the optimum temperature calculating means (51). Opening control means (5
2) A protection device for a refrigerating device, which is provided with.