JPH0460328A - Operation control device for air conditioner - Google Patents

Abstract

PURPOSE:To prevent over-cooling of lubricant oil of a compressor and further prevent a phenomenon of locking in the compressor by a method wherein when a continuous operating time of the compressor is shorter than a predetermined time and an air conditioning capability of freezing cycle is too high as compared with an air conditioning load, a room set temperature is slightly shifted to extend the continuous operating time or a stopping time of the compressor. CONSTITUTION:A surface temperature TC of a compressor 1 is fed from a temperature sensor 10, a surface temperature Teo of an outdoor heat exchanger 3 is fed from a temperature sensor 11., a surface temperature Tei of an indoor heat exchanger 9 is fed from a temperature sensor 12 and an indoor temperature T is fed from a temperature sensor 13 into a control device 20, respectively. The control device 20 performs a controlling operation for the compressor. At this time, in the event that an operation continuing time of the compressor 1 is 5 minutes or shorter, the temperature TC of the compressor is lower than the temperature Teo of the outdoor heat exchanger (during a cooling operation) or the temperature TC of the compressor is lower than the temperature Tei of the indoor heat exchanger (during a heating operation), the room temperature set value is slightly shifted in such a direction as one in which an operating time of the compressor is extended.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention has a refrigeration cycle that includes a compressor, a condenser, and an evaporator, and the indoor temperature reaches a set room temperature. The present invention relates to an operation control device for an air conditioner that performs ON/OFF control operation of a refrigeration cycle so that the refrigeration cycle approaches the vehicle.

(Prior art) In temperature control in an air conditioner, the indoor temperature T of the object of air conditioning is usually detected and set as the room temperature set value T.
In comparison, the ON/OFF control of the compressor is performed so that the room temperature T is maintained within a predetermined control range above and below the room temperature set value T.

That is, the relationship between the indoor temperature T and the room temperature set value T is expressed as follows.

T −α≦T≦T +β ... (1) a
a Here, α and β are control widths, usually 0.25≦α
=β≦1.00. The temperature for determining ON/OFF of this compressor is defined as follows.

T, d=Ta-α...(2)T-
T + β ... (3) au
a The temperature Tad will be referred to as the lower limit temperature, and the temperature Tau will be referred to as the upper limit temperature.

If the lower limit temperature Tad and upper limit temperature Tau are used, (1
) and (2) are expressed as follows.

Tad≦T≦Tau (4) In order to achieve such temperature control, in reality, in the case of heating operation, as shown in Fig. 10, the indoor temperature T or lower limit temperature Tad is lowered. When the compressor is turned on and the upper limit temperature T
(or above), turn off the compressor. In the case of cooling operation, as shown in FIG. 11, the compressor is turned on when the indoor temperature T becomes higher than the upper limit temperature T, and is turned off when the lower limit temperature Tad is reached.

(Problem to be solved by the invention) In the conventional operation control device, in order to keep the indoor temperature T within the range of equation (4), the compressor is turned on and off.
Since F control is performed depending only on the indoor temperature T, for example, if an air conditioner with excessive air conditioning capacity is installed compared to the air conditioning load, the continuous operation time of the compressor will be shortened, and as a result, The ON/OFF operation of the compressor will be repeated frequently. If this operation continues, the compressor surface temperature will become lower than the condenser temperature, and the compressor lubricating oil will become supercooled due to the excessive liquid backing of the compressor refrigerant gas, causing a lubricating oil shortage and locking the compressor. There have been times when I have been

SUMMARY OF THE INVENTION An object of the present invention is to provide an operation control device for an air conditioner that can prevent overcooling of compressor lubricating oil and locking of the compressor that may occur due to the surface temperature of the compressor becoming too low. .

[Structure of the invention]

(Means for Solving the Problem) In order to achieve the above object, the operation control device for an air conditioner according to the present invention includes a first means for detecting when the continuous operation time of the compressor is below a predetermined value. , a second means for detecting when the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load; and a room temperature setting value of the compressor based on the logical product of both the first means and the second means. The present invention is characterized by comprising a third means for slightly shifting in a direction in which the operating time becomes longer.

(Function) If the continuous operation time of the compressor is less than a predetermined value, this is a sign that the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load, so this should be noted first. In addition to this, it is additionally confirmed that the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load, and the room temperature set point is slightly shifted to increase the continuous operation time or stop time of the compressor. By doing so, it is possible to prevent overcooling due to short-time ON/OFF of the compressor.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 2 shows the arrangement positions of an air conditioner to which the present invention is applied and a control temperature sensor. The refrigeration cycle that constitutes this air conditioner includes a compressor 1, a four-way valve 2, an outdoor heat exchanger 3, and a check valve 4D.

4R, a cooling capillary tube 5, a heating capillary tube 6, a packed valve 7.8, and an indoor heat exchanger 9.

This refrigeration cycle can selectively perform cooling operation or heating operation by switching the four-way valve 2. In the case of cooling operation, the outdoor heat exchanger 3 functions as a condenser, the indoor heat exchanger 9 functions as an evaporator, and the refrigerant is transferred from the compressor 1 to the four-way valve 2, the outdoor heat exchanger 3, the capillary tube 5, and the reverse. It flows back to the compressor 1 through the stop valve 4R, packed valve 7, indoor heat exchanger 9, packed valve 8, and four-way valve 2.

In the case of heating operation, the outdoor heat exchanger 3 functions as an evaporator, the indoor heat exchanger 9 functions as a condenser, and the refrigerant is transferred from the compressor 1 to the four-way valve 2, packed valve 8, indoor heat exchanger 9,
Packed valve 7, capillary tube 6, check valve 4D
, an outdoor heat exchanger 3, and a four-way valve 2 to return to the compressor 1.

In the above refrigeration cycle, as temperature detection means, a temperature sensor 0 detects the surface temperature of the compressor 1 as the compressor temperature T, and a temperature sensor 0 detects the surface temperature of the outdoor heat exchanger 3 as the outdoor heat exchanger T. 11. Adjust the surface temperature of indoor heat exchanger 9 to indoor heat exchanger T.
, a temperature sensor 2 for detecting the temperature T, and a temperature sensor 3 for detecting the indoor temperature T. Detection signals from these temperature sensors are respectively introduced into the control device 20. The outdoor heat exchanger temperature T and the indoor heat exchanger temperature T are both eo
Rather than el being used,
Only one of the temperatures that acts as a condenser is selectively used, that is, the outdoor heat exchanger temperature T in the case of cooling operation, and the indoor heat exchanger temperature T in the case of heating operation. .

The control device 20 is substantially composed of a microcomputer, and performs known compressor control and implements the present invention according to the flow chart described below. The compressor 1 is ON/OFF controlled through the control device 20 basically according to a known control method so that the indoor temperature T detected by the temperature sensor 13 satisfies equation (4).

When the indoor temperature T falls below the lower limit temperature Tad (in the case of heating operation) or rises above the upper limit temperature T (in the case of cooling operation) and the compressor is turned on, the flowchart of FIG. 1 according to the present invention is performed. control is executed.

In the embodiment shown in FIG. 1, as a means for detecting when the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load, a means for detecting when the compressor surface temperature or the condenser temperature has fallen below is provided. This shows that.

First, as a measure of the operating frequency of the compressor 1, it is checked whether the ON time, that is, the continuous operating time, is 5 minutes or less (step Sl). If the ON time is not less than 5 minutes,
It continues the "normal operation" (step S2) assuming that it is in a normal state. If the ON time is less than 5 minutes,
This is a situation that requires attention, and whether the compressor temperature T is lower than the outdoor heat exchanger temperature T (in the case of cooling operation), or whether the compressor temperature T is lower than the indoor heat exchanger temperature T (Cel (in heating operation) ) is checked (step S3)
. If it is determined here that the temperature is not low, then the "normal operation" (step S2) is continued. If it is determined to be "low", then a determination is made as to whether the heating operation or the cooling operation is to be performed (8 steps S4). According to the result of this judgment, in the case of heating operation, the upper limit temperature Tau, which is the OFF temperature of the compressor 1, is increased by 0.5°C, and T , -T +0.5 ... (
5) au au Then, in step S5), in the case of cooling operation, the lower limit temperature "ad", which is the OFF temperature of the compressor 1, is set to 0.5.
Down by ℃, T −T −0,,5... (6) ad
ad (step S6). In this way, turn off compressor 1.
By increasing the temperature by 0.5°C during heating operation and decreasing the temperature by 0.5°C during cooling operation, the compressor 1 can be operated for longer in heating operation (see Figure 3) or cooling operation (see Figure 4). ) will continue. Even if the operating time of the compressor 1 is extended by changing the OFF temperature of the compressor 1 in this way, the operating time of the compressor 1 at one time is still 5.
It is possible for the quantity to go down. In such a case, the OFF temperature of the compressor 1 is further increased by 0.5° C. (during heating operation) or decreased (during cooling operation). However, if such setting changes are repeated too many times, the temperature setting value T 1 will be substantially changed significantly, which is undesirable. Therefore, in the case of heating operation, set the maximum limit value MAX of the upper limit temperature T and check whether it does not exceed it (step S7), and in the case of cooling operation, set the minimum limit value MIN of the lower limit temperature Taθ. It is checked whether the value is lower than that (step S8).

In the case of heating operation, the above operation is repeated until the upper limit temperature T or the maximum limit value MAXu is exceeded.
If exceeds the maximum limit value MAX, it is determined that the air conditioning capacity is too large compared to the air conditioning load, and the operation of the air conditioner is stopped (Step S9), and an error message is displayed (Step S9). 510).

Similarly, in the case of cooling operation, the above-mentioned operation is repeated as long as the lower limit temperature Tad does not fall below the minimum limit value MIN,
If the lower limit temperature Tad is lower than the minimum limit value MIN, the operation of the air conditioner is stopped (step S9), and an abnormality is displayed (step 511).

As a result of the above control, in the case of heating operation, as shown in FIG. 3, due to the action of rT −au T +0.5J in step S5 of FIG. 1, and in the case of cooling operation, u is as shown in FIG. r according to step S6 in FIG.
Due to the action of T aa ”” T aa O, 5J,
It can be seen that the operating time (continuous ON time) of the compressor 1 is extended by approximately the corresponding time, and the OFF time of the compressor 1 is also extended correspondingly. However, as a result of the above control, step S1 and step S
It is unavoidable that only in the case of "YES" in both cases 3, the room temperature set value will be substantially increased slightly in the case of heating operation, and substantially reduced slightly in case of cooling operation.

In this way, the situation where the compressor 1 frequently repeats ON/OFF operations due to the air conditioning capacity being too large compared to the air conditioning load can be largely avoided.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6.

In this embodiment, contrary to the case of the above-mentioned first embodiment, the calculation formula in step S5 of FIG. The calculation formula in S6 is T −T +0.5
... (8)au
Let it be au. Other control aspects are completely the same as in the first embodiment. In this embodiment, when the ON time of the compressor 1, that is, the continuous operation time is 5 minutes or less, and the compressor temperature T is lower than the condenser temperature, the lower limit temperature Tad is set to 0.5°C in the case of heating operation. By lowering the upper limit temperature T in units of au 0.5°C in the case of cooling operation, the compressor 1 can be turned on.
This aims to extend the time and OFF time. As can be seen from FIGS. 5 and 6, even with such control, the ON/OFF operation of the compressor 1 is controlled in the same manner as in the first embodiment shown in FIGS. 1, 3, and 4. The frequency can be reduced. However, in this embodiment, only when "YES=" in both steps S1 and S3, the room temperature set value is substantially slightly lowered in the case of heating operation, and substantially slightly lowered in the case of cooling operation. It will be elevated.

As described above, in this embodiment as well, the compressor 1 is overheated due to the air conditioning capacity being too large compared to the air conditioning load.
A situation in which N/OFF operations are frequently repeated can be largely avoided.

Next, a third embodiment of the present invention will be described with reference to FIGS. 7 and 8.

In this embodiment, in order to avoid the situation where the temperature setting value is substantially increased or decreased in the first embodiment and the second embodiment, the calculation formula in step S5 in FIG. 1 is changed to T −T +0 .25...(9
)au au T, d-Tad-0,25-...(10), and similarly, the calculation formula in step S6 is T-T+0.
25...(11) au au Tad-T, d-0, 25...(12). Other control aspects are largely the same as in the first embodiment. The feature of this embodiment is that the control range is set equally above and below the temperature set value T in this way. In this embodiment, when the ON time of the compressor 1, that is, the continuous operation time becomes 5 minutes or less, and the compressor temperature T becomes lower than the condenser temperature, the lower limit is set for both heating operation and cooling operation. The temperature Tad is lowered in units of 0.25°C, and the upper limit temperature T is increased in units of 0.25°C. By doing this, as can be seen from the figure, the ON time and OF of the compressor 1 are adjusted as in each of the above embodiments.
It is possible to extend the F time and reduce the frequency of ON/OFF operation of the compressor 1. In this example, (9) to (1
2) Since the upper limit temperature T au and lower limit temperature Tad are set and changed with equal control ranges above and below the room temperature T, the room temperature set value is corrected upward or downward on average. There is a characteristic that there is no.

Thus, in this embodiment as well, the compressor 1 is turned on/off due to the air conditioning capacity being too large compared to the air conditioning load.
A situation in which the F operation is frequently repeated can be largely avoided.

In each of the embodiments described above, the temperature control width, that is, the O
The difference between the temperature for N control and the temperature for OFF control is 0.5℃.
It was explained as expanding in units.

However, this unit expansion width is not limited to units of 0.5°C, and may be modified transiently in units of 1°C, for example.

Next, a fourth embodiment of the present invention will be described with reference to the flowchart of FIG.

This embodiment is a means for detecting that the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load, based on the condition that the continuous operation time of the compressor is less than a predetermined value, or that it is detected more than a predetermined number of times. It is equipped with a means for issuing a detection output, and the processing content of step S3 in FIG. 1 is changed to step Sll. In step Sll, when the judgment result in step S1 is that the ON time of the compressor 1 is 5 minutes or less, the content of the subsequent judgment is that the compressor If the ON time of 1 is less than 5 minutes or the first time, normal operation is continued (step S2).

However, if the situation in which the ON time of the compressor 1 is 5 minutes or less occurs two or more times, the process from step 84 onward is performed as described in step 1 with reference to FIG. 1 et seq.
- Execute according to the third embodiment.

This embodiment also achieves the same functions and effects as those of the first to third embodiments.

〔Effect of the invention〕

As described above, according to the present invention, the compressor surface Overcooling of the compressor lubricating oil and locking of the compressor, which may occur due to the temperature becoming too low, can be largely prevented.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing one embodiment of the present invention, and FIG.
The figure shows the system configuration and the arrangement of temperature sensors of an air conditioner to which the present invention is applied, and Figure 3 shows the indoor temperature and compressor ON/OFF operation mode when the control mode shown in Figure 1 is used during heating operation. FIG. 4 is a time chart showing an example of the indoor temperature and compressor ON/OFF operation mode when using the control mode shown in FIG. 1 during cooling operation, and FIG. Fig. 6 is a time chart showing an example of the indoor temperature and compressor ON/OFF operation mode when using a control mode different from that shown in Fig. 1, and Fig. 6 shows the indoor temperature when using a control mode different from that shown in Fig. 1 during cooling operation. and compressor ON/
FIG. 7 is a time chart showing an example of an OFF operation mode; FIG. The figure is a time chart showing an example of indoor temperature and compressor ON/OFF operation mode when a control mode is different from that shown in FIG. 1 during cooling operation, and FIG. 9 shows an example different from that shown in FIG. 1. flowchart,
Fig. 10 is a time chart showing an example of the indoor temperature and compressor ON/OFF operation mode when the conventional control mode is used during heating operation, and Fig. 11 is the indoor temperature when the conventional control mode is used during cooling operation. 3 is a time chart showing an example of the ON/OFF operation mode of the compressor. DESCRIPTION OF SYMBOLS 1... Compressor, 2... Four-way valve, 3... Outdoor heat exchanger, 9... Indoor heat exchanger, 10, 11.12... Temperature sensor. Applicant's agent: Sato-Osu Display of written amendment case 2008 Patent Application No. 170688 Name of the invention Person who amends the operation control device of an air conditioning system Relationship with the case Co., Ltd.

Claims (1)

[Claims] 1. An air conditioner that includes a refrigeration cycle including a compressor, a condenser, and an evaporator, and operates the refrigeration cycle in an ON/OFF manner so that the indoor temperature approaches a set room temperature. In the operation control device, a first means detects when the continuous operation time of the compressor is less than a predetermined value, and a first means detects when the air conditioning capacity of the refrigeration cycle is too large compared to the air conditioning load. and third means for slightly shifting the room temperature set value in the direction of lengthening the operating time of the compressor using both the outputs of the first means and the second means as a logical product condition. An operation control device for an air conditioner characterized by: 2. The second means includes a means for detecting a compressor surface temperature, a means for detecting a condenser temperature, and a means for emitting a detection output when the compressor surface temperature becomes equal to or lower than the condenser temperature. The operation control device according to claim 1, wherein: 3. The second means is configured to issue a detection output on condition that the first means detects a situation in which the continuous operation time of the compressor is below a predetermined value for a predetermined number of times or more. , The operation control device according to claim 1.