JPH07104082B2 - Heat pump system - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a heat pump system using external air as a heat source, and more specifically, defrosting according to operating conditions of a plurality of use side heat exchangers. This relates to a heat pump system that operates.

(Prior Art) For example, in a separate type air conditioner or the like, frost is formed on the outdoor heat exchanger during the heating operation, which reduces the heating capacity. It may be necessary to switch to operation. In a conventional air conditioner, in order to perform this switching automatically, the evaporation temperature of the outdoor heat exchanger decreases due to the decrease in heat exchange efficiency with the outside air due to frost formation, which reduces the outdoor heat exchanger itself. By utilizing the phenomenon that the temperature also decreases, when the temperature of the outdoor heat exchanger becomes lower than the defrosting start temperature, the refrigeration circuit is switched to the reverse cycle to start the defrosting operation. In this case, the defrosting start temperature is the defrosting amount of the device at the defrosting start time such that the defrosting operation time and the defrosting operation interval that do not significantly deteriorate the heating performance and the habitability are obtained. From the above, the temperature of the outdoor heat exchanger corresponding to this frost formation amount is set as the temperature. However, the actual amount of frost is strongly influenced by, for example, the humidity in the outside air, and even if the outdoor heat exchanger temperature is the same, the amount of frost may differ greatly depending on the level of humidity. For example, at the defrosting start temperature set assuming a humidity of 60%, for example, when operating on a day with a humidity of 30%, there is almost no frosting at that temperature, or the frosting speed is slow and defrosting is immediate. It may not be necessary to switch to frost operation. In the conventional device, even in these cases, there is a problem that the temperature detection signal becomes equal to or lower than the set temperature and the operation is switched to the unnecessary defrosting operation.

Therefore, the present applicant has previously proposed a defrosting device that can change the set temperature according to the situation (see Japanese Patent Application No. 60-186279). FIG. 5 schematically shows a control function block diagram of the defrosting device. As shown in FIG. 5, in the device, the temperature of the outdoor heat exchanger is higher than the temperature set by the defrosting start temperature setting means 51. When the temperature detected by the detecting means 52 becomes low,
Defrosting operation is switched to the defrosting operation by the defrosting operation control means 53, and defrosting is started, and the defrosting is finished by this operation and the temperature of the outdoor heat exchanger rises. When the detected temperature exceeds the temperature set by the defrost release temperature setting means 54, the defrost operation by the defrost operation control means 53 is stopped and the heating operation is restarted. Then, the device is provided with a defrosting time measuring means 55 for measuring the operation time of the defrosting operation, and the actual defrosting operation time measured by this means, in the defrosting start temperature changing means 56, The reference defrosting time setting means 57 is compared with a preset reference time, and the previous set temperature in the defrosting start temperature setting means 51 is changed according to the difference.
That is, in a device having a substantially constant defrosting ability, if the amount of frosting at the start of defrosting is constant, the time required for the defrosting should also be constant, and therefore the actual defrosting is required. The defrosting start temperature is changed so that the time matches the preset standard defrosting time, and as a result, the defrosting operation is attempted to start when the actual amount of frost has reached a certain level. is there. For example, when the humidity in the outside air is low and the amount of frost is small even if the temperature of the outdoor heat exchanger decreases, the defrosting at this time ends in a short time, and from this result,
If the next defrost start temperature is set to a lower temperature and the defrosting operation takes too long due to the large amount of frost, the next time the amount of frost is less than the above The defrosting start temperature is set higher than before so that the operation can be switched to operation. By performing such a change operation, when the amount of frost on the outdoor heat exchanger actually reaches a certain amount at which defrosting should be started, the defrosting operation is switched to. As a result, the heating operation is continued until the performance of the outdoor heat exchanger actually decreases, and the proper defrosting operation is performed to try to improve the heating utilization efficiency.

(Problems to be solved by the invention) By the way, in recent years, for example, one outdoor heat exchanger, a plurality of indoor heat exchangers, and further a heat exchanger for bath heating and a heat exchanger for hot water heating are provided. Multi-type heat pump systems connected in parallel are emerging. In this case, in the above defrosting operation, even when the amount of frost on the outdoor heat exchanger at the start of defrosting is substantially the same, the time required for the defrosting is the time immediately before the start of defrosting. It will be greatly affected by the operating conditions of each heat exchanger on the user side. In the defrosting operation operation in which the refrigeration circuit is switched to the reverse cycle, the use side heat exchanger acts as an evaporator as in the cooling cycle, and the circulating refrigerant is absorbed from around the use side heat exchanger at this time. This is because the amount of heat generated is radiated by the outdoor heat exchanger for defrosting. Therefore,
The greater the amount of heat that can be absorbed on the utilization side heat exchanger side, the greater the defrosting capacity, and the defrosting will be completed in a short time. And the defrosting capacity increases as the number of operating heat exchangers on the use side increases, so that there is only one heat exchanger on the use side and the defrosting capacity is substantially constant. In the multi-type heat pump system, the time required for completion of defrosting varies depending on the number of user side heat exchangers that were in the heating operation state immediately before the start of defrosting. For this reason, in the multi-type heat pump system, there is a problem in that the proper defrosting operation condition cannot be obtained by the conventional method of keeping the defrosting time constant, and therefore the heating capacity cannot be improved.

The present invention has been made to solve the above problems, and an object thereof is a multi-type heat pump system that enables an appropriate defrosting operation operation according to the operation status of a plurality of use side heat exchangers. To provide.

(Means for Solving Problems) Therefore, the heat pump system of the present invention is a heat pump system in which a plurality of utilization side heat exchangers 15 are connected to one heat source side heat exchanger 3 as shown in FIG. As shown in, the temperature detecting means 25 for detecting the temperature of the heat source side heat exchanger 3 to start the defrosting operation, and the temperature detecting means 25.
Along with starting the defrosting operation when the detected temperature at or below the defrosting starting temperature, defrosting operation control means 32 for stopping the defrosting operation when the end temperature is exceeded, and the defrosting operation The defrosting start temperature changing means 42 for changing the defrosting starting temperature by comparing the operating time with the reference defrosting time is provided, and further, the total load capacity value of each of the utilization side heat exchangers 15 having an operation request is set. A load capacity grasping means 39 for grasping, a time storage means 40 for preliminarily storing a reference defrosting time according to each total load capacity value,
The time storage means according to the grasped total load capacity value
Reference defrost time setting means 41 for setting the reference defrost time based on 40 is provided.

(Operation) In the heat pump system configured as described above, a load capacity value substantially corresponding to each heat absorption capacity is set in each usage side heat exchanger 15, and the load capacity grasping means 39
Then, the sum of the above-mentioned load capacity values of the use side heat exchanger 15 that has an operation request is obtained. Then, from the relationship between the load capacity value and the reference defrosting time with respect to a constant frosting amount to start defrosting stored in advance in the time storage means 40, the reference defrosting time setting means 41, the total load The standard defrosting time is selected according to the capacity value. Therefore, even when the operating state of the use side heat exchanger 15 is different, the reference defrosting time is set substantially corresponding to the defrosting capacity obtained under that situation, and this time is compared with the actual defrosting operating time. The defrosting start temperature is changed by the defrosting start temperature changing means 42 according to the difference, so that the defrosting operation is switched to when the heat source side heat exchanger 3 has a certain amount of frost formation. You can
This makes it possible to suppress the defrosting operation operation to the necessary minimum and improve the utilization efficiency.

(Examples) Next, specific examples of the present invention configured as an air conditioner will be described in detail with reference to the drawings.

First, FIG. 2 shows a refrigerant piping system of a multi-type air conditioner having four indoor units. In the figure, X is an outdoor unit, and A, B, C, and D are the first unit, respectively.
~ Shows a fourth indoor unit. Outdoor unit X above
It includes a compressor 1 which is capable controlled by an inverter 1 _a, as shown in solid lines in the figure at the time of cooling operation, also respectively Setsu換Ru four-way valve 2 as shown by a broken line in the figure at the time of heating operation, the blower fan 3 _a The outdoor heat exchanger 3 which has, the 1st electric valve 4, the liquid receiver 5, the 2nd electric valves 6-9 which are provided corresponding to each of the above-mentioned indoor units A and D, and the accumulator 10 are respectively provided. Each of the devices 1 to 10 has a refrigerant pipe 11
.. are connected so that the refrigerant can be circulated. The outdoor heat exchanger 3 serves as a heat source side heat exchanger, while the indoor units A to D are provided with an indoor heat exchanger 15 serving as a use side heat exchanger and an indoor fan 16, respectively. ing.

The four indoor units A to D are connected to the one outdoor unit X by refrigerant pipes 18 ... And a refrigerant circulation circuit 19 is formed. That is, during the cooling operation, the refrigerant is circulated as shown by the solid line arrows in the figure, so that the heat absorbed from the indoors by the indoor heat exchangers 15 is repeatedly released from the outdoor heat exchangers 3 to the outside air so that the insides of the respective rooms are cooled. While cooling, on the other hand, during the heating operation, the refrigerant is circulated as indicated by a broken line arrow in the figure, so that the support of heat can be reversed to heat each room. In this type of multi-type air conditioner, when the number of operated indoor units changes, the air-conditioning load changes significantly. The machine 1 is adopted and the air conditioning operation is performed according to the load fluctuation. In the figure, 20 is a capillary tube, and by returning the refrigerant in the receiver 5 to the accumulator 10 by this tube 20, the evaporation temperature during the refrigeration cycle is detected at the outlet of the capillary tube 20. There is. Further, 22 is a thermistor for detecting the discharge gas temperature of the refrigerant, 23 is a liquid closing valve, and 24 is a gas closing valve.

The frost formation amount detection signal in the defrosting operation is given by the thermistor 25 for measuring the temperature of the outdoor heat exchanger, which is attached to the pipe of the outdoor heat exchanger 3. When the measured temperature becomes equal to or lower than the set temperature, it is temporarily determined that the amount of frost that needs to be defrosted has been reached, the blower fan _3a and the indoor fan 16 are stopped, and the four-way selector valve 2 is closed. The direction is switched to start the reverse cycle defrosting operation. Then, the frost adhering to the outdoor heat exchanger 3 is removed, and when the temperature of the outdoor heat exchanger 3 detected by the thermistor 25 reaches the defrosting end temperature, the defrosting operation is terminated and heating is performed. It is designed to restart driving.

Next, the operation control circuit of the air conditioner will be described with reference to FIG. As shown in the figure, the outdoor unit X has an outdoor control device 27 having a compressor frequency control unit 26, a defrost control unit 30, and a load capacity grasping unit 39. To the compressor frequency control unit 26 inverter 1 _a is connected, the inverter 1 _a is connected to the compressor 1 of the drive motor 28. On the other hand, each of the indoor units A to D has an indoor control device 50, and a remote controller 46 and an indoor thermostat 47 are connected to the indoor control device 50.

In the operation control circuit having the above configuration, first, the compressor frequency control unit 26 and the load capacity grasping unit 39 for controlling the drive of the compressor according to the change in the load capacity of the indoor units A to D side.
The configuration will be described. The remote controller 46 has an operation switch for operating the indoor units A to D,
And a temperature setting unit for setting a desired temperature. And each indoor control device 50 ... 50 and outdoor control device 27
Is connected with a signal line 29, and the indoor control device 50
Tells the outdoor control unit 27 the following three signals, that is, the operation switch ON in the indoor unit and the thermostat.
The operation request signal output at the time of ON, the ΔT signal corresponding to the difference between the room temperature and the set temperature by the indoor thermostat 47, and the model code signal are respectively output.

Further, in the outdoor control device 27, each indoor control device 50 ...
Based on the model code signal output from 50, the load capacity grasping section 39 causes all the indoor units A to D that are requested to operate.
The load capacity ΣS is grasped, which is carried out by the following procedure. First, the model code signal output from the indoor control device 50 ... 50 is determined according to the capacity of each indoor heat exchanger 15, and for example, for a capacity of 2240 kcal / h, "000 Code is "001" for 2800 kcal / h and "01" for 3550 kcal / h
"0" is also defined as "011" at 4500 kcal / h, and these codes are for each indoor unit A ~
It is stored for each D. Further, in the load capacity grasping section 39, the storage section 44 stores the load capacity value S corresponding to the model code. This load capacity value S is 2240kc
2800k with al / h (model code "000") as reference value "1"
cal / h (model code "001") to "1.25", 3550kcal / h
(Model code "010") is set to "1.5" and 4500kcal / h (Model code "011") is set to "2". The load capacitance value S is read out for each of A to D, and the sum ΣS of these is calculated.

In the outdoor control device 27, the total load capacity value ΣS of the indoor units A to D for which the operation request is made as described above is grasped, but the difference between this and the room temperature by the indoor thermostat 47 and the set temperature. The frequency of the compressor 1 is controlled by the compressor frequency control unit 26 based on the corresponding signal ΔT. Therefore, for example, when the number of indoor units A to D that are requested to operate is large, the total load capacity value ΣS generally becomes large. At this time, the compressor 1 is driven at a high frequency,
As a result, the air-conditioning capacity is increased and each room is simultaneously air-conditioned with the capacity meeting the demand.

Next, the control circuit configuration of the defrosting operation will be described. The defrost control unit 30 includes a defrost start and end signal generation unit 31, a defrost operation control unit 32 that is a defrost operation control unit, a timer 33, and a defrost start temperature generation unit 34. . The detection temperature of the thermistor 25, which serves as a temperature detecting means for detecting the temperature of the outdoor heat exchanger 3, is input to the defrosting start and end signal generating unit 31, which is a defrosting start temperature generating unit described later.
When the temperature is below the defrost start temperature given by 34, the defrost start signal is output, and when the preset defrost end set temperature is exceeded during the defrost operation, the defrost end signal is output. Start temperature comparison circuit 35, end temperature comparison circuit 36
Is provided. Then, in response to the defrosting start signal and the defrosting end signal, the defrosting operation control unit 32 causes the blower fan.
3 is stopped and _a and the indoor fan 16 switched four-way selector valve 2 in the solid arrow direction (see FIG. 2), also outputs a defrosting frequency fixing signal to the compressor frequency control unit 26, the defrosting operation Is carried out. The elapsed time of this defrosting operation is a timer
Made to be measured by 33.

The defrost start temperature is given by the defrost start temperature setting unit 37 of the defrost start temperature generation unit 34. Regarding the defrosting start temperature, for example, the higher the compressor driving frequency, and thus the larger the refrigerant circulation amount, the lower the evaporation temperature in the normal operation of the outdoor heat exchanger 3, which causes the tendency of the evaporation temperature. The defrosting start temperature is determined by the following equation.

Td1 = −Ad × F−Cd (Toal−Toa) −Bd where, Td1: Defrost start temperature Ad, Cd: Coefficient F: Compressor drive frequency Toal: Outside air temperature during operation Toa: Reference outside air temperature Bd: Exclusion Therefore, in the defrosting start temperature setting unit 37, the outside air temperature signal detected by the outside air temperature measurement thermistor 49, the frequency signal output of the compressor frequency control unit 26, and the reference start temperature. With each coefficient value and constant value in the above formula stored in advance in the storage unit 38,
Further, from the correction constant Bd in the above formula obtained by the procedure described below, the defrosting start temperature Td1 is calculated,
It is input to the start temperature comparison circuit 35.

The above Bd is calculated by the following equation.

Bd = Bd−Ed × (td−td1) where Bd: Coefficient td: Time required for the previous defrosting td1: Standard defrosting time (Bd is the initial value until the first defrosting operation is performed. That is, every time the defrosting operation is actually performed, the Bd at that time is
Based on the difference between the time required for defrosting and the reference defrosting time, the value is further changed to the next Bd. However, as described above, in the multi-type heat pump system, since the defrosting capacity greatly varies depending on the operating condition of the heat exchanger on the use side, even if the amount of frost is constant, the defrosting time is It is not constant, and a standard defrost time is required for each operating condition. For this reason, in the above-described embodiment, the total load capacity value ΣS of the indoor units A to D having the operation request, which is grasped by the load capacity grasping section 39 serving as the above-mentioned load capacity grasping means.
Is a value substantially corresponding to the defrosting ability at each time, and based on this, each reference defrosting time is set. That is, the total load capacity value ΣS grasped by the load capacity grasping section 39 is inputted to the reference defrosting time setting section 41 serving as a reference defrosting time setting means. On the other hand, in the time storage unit 40 serving as a time storage means, for each ΣS value, for example, 1.25 or less, 3 minutes 30 seconds,
The ΣS value and the reference time required for defrosting are stored in advance as a data table for a fixed amount of frost to start defrosting, such as 3 minutes for 1.25 to 2 and 2 minutes and 30 seconds for 2.25 or more. There is. Therefore, in the reference defrosting time setting unit 41, according to the ΣS value input from the load capacity grasping unit 39,
The reference defrosting time td1 corresponding to this is selected from the time storage unit 40, and this is output to the defrosting start temperature changing unit 42 serving as a defrosting start temperature changing unit.

The ΣS value is a value corresponding to the heating capacity of the indoor heat exchanger in operation, and this is also the heat absorption on the indoor heat exchanger side during operation that acts as a heat supply source during defrosting operation. It is a value that substantially corresponds to the capacity, that is, the defrosting capacity. Therefore, the defrosting ability according to the operating condition on the indoor heat exchanger side before defrosting can be grasped, and the reference defrosting time at this time can be given.

In the defrosting start temperature changing unit 42, the reference defrosting time td1
And the time required for the actual defrosting measured by the timer 33
Bd is calculated from td by the above equation and is output to the defrosting start temperature setting unit 37. Then, the defrosting start temperature setting unit 37 calculates the next defrosting start temperature according to the Bd and outputs it to the start temperature comparison circuit 35. The signal of the timer 33 during time counting is input to the maximum permissible time comparison circuit 43 and compared with the maximum permissible set value tf (for example, 8 minutes) of the defrosting time, and when this set value is exceeded, Temporarily suspends the defrosting operation and returns to heating operation.
It is designed to prevent a significant decrease in habitability.

Next, the operating state of the above embodiment will be described based on the control flowchart of the defrosting operation of FIG. In the figure,
First, in heating operation, the defrosting start temperature Td1 is set to step S
Initialized at 1, the heating operation is started in step S2. Then, in steps S3 and S4, the temperature Te of the outdoor heat exchanger is detected and compared with Td1. If it is higher than Td1, the process returns to step S2 and the heating operation is continued. Then, when Td1 or less, it is determined that the amount of frost attached to the outdoor heat exchanger exceeds a predetermined amount, the process proceeds from step S4 to step S5, the heating operation is interrupted, and the defrosting operation is started. . At this time, counting of the defrosting operation time td is started in step S6, and this count value td reaches the maximum allowable set value tf of the defrosting time in steps S7 and S8, or Te exceeds the defrosting end temperature Tf. The defrosting operation is continued in steps S5 to S8 while determining whether or not it is. Then, if Te exceeds Tf before td exceeds tf, the process proceeds from step S8 to step S9, the defrosting operation is stopped, and the step
The counting of td is stopped in S10, and the defrosting start temperature Td1 is reset in steps S11 to S14 based on the td value at that time. That is, in step S11, the total load capacity value ΣS is grasped based on the indoor heat exchanger that is requested to operate at that time, and in step S12, the corresponding reference defrosting time td1 is selected from this ΣS, and step S13 In, the above td and td1 are compared and calculated to obtain Bd,
Then, in step S14, a new defrosting start temperature Td1 is calculated from this Bd, the process proceeds to step S2, and heating is restarted. Therefore, the next defrosting start will be performed based on the newly set start temperature Td1. By repeating such a defrosting operation operation, an appropriate defrosting operation according to the actual amount of frost formation is performed, and the heating efficiency can be improved. In step S7, the defrosting operation time td is the maximum allowable set time tf.
If it is determined that the temperature exceeds the limit, the process proceeds to steps S15 and S16 to stop the defrosting operation, the td count is interrupted, and as described above, the process proceeds to step S2 to restart the heating operation. Becomes

As described above, in the multi-type heat pump system of the above embodiment, since the defrosting start set temperature is modified and changed so that the proper defrosting operation is performed according to the actual frost formation amount, The temperature of the outdoor heat exchanger, when performing a defrosting operation in comparison with a constant set temperature, for example, there are cases where the defrosting operation is started even when no frost is formed, but in the above embodiment, this Such useless defrosting operation is suppressed, the heating operation time can be extended, and the heating efficiency is improved.
Further, the heating utilization efficiency is different for each device due to the difference in defrosting start timing due to the product variation of the thermistor as the temperature detecting means, but according to the above-mentioned embodiment, the correction according to the actual frost formation amount is made. Therefore, defrosting is started at a substantially constant amount of frost formation, and it is possible to reduce variations among devices.

In addition, although the example configured as an air conditioner is shown in the above-described embodiment, as another utilization side heat exchanger, it can be applied to other heat pump systems having a heat exchanger for hot water supply, bath heating, etc. it can. Also, as the load capacity value, the value corresponding to the capacity of each indoor heat exchanger was set,
If the capacities of the usage-side heat exchangers do not differ so much, it is possible to set them to "1" and set them as values corresponding to the operating number. Furthermore, in the above, an example of grasping the load capacity value of the indoor heat exchanger during operation (thermo ON) was shown, but the operation switch ON operation (thermo OFF
(Including the above), the load capacity value of the indoor heat exchanger may be grasped and implemented. In the above embodiment, when the operating time required for defrosting is shorter than the reference defrosting time, the defrosting start temperature is changed to the low temperature side, and when it is long, the temperature is changed to the high temperature side. For example, when it is only necessary to prevent the defrosting switching operation when no frost is formed, it is possible to adopt a configuration that only changes to the low temperature side, or conversely, to prevent a significant decrease in heating capacity. It is also possible to configure so that only the change to the high temperature side is made when the above is required.

(Effects of the Invention) As described above, in the heat pump system of the present invention, the temperature of the heat source side heat exchanger is detected, and the defrosting operation is started when the temperature falls below the defrosting start set temperature. However, among the multiple heat exchangers on the use side that were installed, the heat exchanger on the use side that was operating before the start of defrosting was identified, the defrosting capacity at that time was calculated, and The defrosting start temperature is changed by determining the reference defrosting time according to the frost ability and comparing this time with the time actually required for defrosting. Defrosting will be started when a certain amount of frost formation that should start defrosting is actually reached, so in a multi-type heat pump system in which the operating condition of the heat exchanger on the use side fluctuates, It is possible to optimize the driving operation, The utilization efficiency can be improved.

[Brief description of drawings]

FIG. 1 is a functional block diagram of defrosting operation control of a heat pump system of the present invention, FIG. 2 is a refrigerant circuit diagram showing an overall configuration of an air conditioner to which the present invention is applied, and FIG. 3 is an apparatus of FIG. 4 is a flow chart of defrosting operation control, and FIG. 5 is a functional block diagram of defrosting control in the conventional apparatus. 3 ... Outdoor heat exchanger (heat source side heat exchanger), 15 ... Indoor heat exchanger (use side heat exchanger), 25 ... Thermistor (temperature detecting means), 32 ... Defrosting operation control section (defrosting) Frost operation control means), 39 ... Load capacity grasping section (load capacity grasping means), 40
...... Time storage section (time storage means), 41 ...... Reference defrost time setting section (reference defrost time setting means), 42 ...... Defrost start temperature changing section (defrost start temperature changing means).

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Takayuki Sugimoto 2 at 1000 Otani, Okamoto-cho, Kusatsu-shi, Shiga Daikin Industry Co., Ltd. Shiga Works (56) Reference JP-A-58-16140 (JP, A)

Claims (1)

[Claims] 1. A heat pump system comprising a plurality of utilization side heat exchangers (15) connected to one heat source side heat exchanger (3), said heat source side for starting defrosting operation. A temperature detecting means (25) for detecting the temperature of the heat exchanger (3), and when the temperature detected by the temperature detecting means (25) becomes below the defrosting start temperature, the defrosting operation is started and ended. Defrosting operation control means (32) for stopping the defrosting operation when the temperature is exceeded, and defrosting start for changing the defrosting start temperature by comparing the operation time of the defrosting operation with the reference defrosting time. A temperature changing means (42) is provided, and further, a load capacity grasping means (39) for grasping the total load capacity value of each of the utilization side heat exchangers (15) which has an operation request, and a total load capacity value According to the total load capacity value grasped above, the time storage means (40) that stores the reference defrosting time in advance And a reference defrost time setting means (41) for setting the reference defrost time based on the time storage means (40).