KR20200086593A - A Control method of heat pump - Google Patents

Abstract

The present invention relates to a heat pump control method and, more specifically, to a heat pump control method wherein the heat pump comprises: a circuit including a compressor, a condenser, an expansion valve (hereinafter called a first expansion valve) and an evaporator, and connected via an airtight coolant line; a condenser fan; an evaporator fan; and a coolant (charging amount) control means (hereinafter called a second expansion valve) charging the circuit with a coolant or recovering the coolant from the circuit. The second expansion valve is configured to include: a recovery valve recovering the coolant from the circuit; a storage space storing the coolant; and a charging valve charging the circuit with the coolant wherein the recovery valve, the storage space, and the charging valve are serially connected, and the second expansion valve is installed between an entrance of the first expansion valve and a low pressure line. The method comprises the steps of: setting a target condensation temperature; when a condensation temperature is lower than the target condensation temperature, allowing the coolant control means to charge the circuit with the coolant; and when a condensation temperature is higher than the target condensation temperature, allowing the coolant control means to recover the coolant from the circuit, wherein during normal operation, a predetermined amount of coolant is allowed to penetrate through the second expansion valve. Accordingly, the heat pump control method can provide improved efficiency by preventing increase of the difference between high and low pressures during the operation of a heat pump.

Description

A control method of heat pump

The present invention relates to a heat pump control method.

A heat pump is a device that transfers heat from a heat source to a destination called a “heater sink”. The heat pump absorbs heat in a cold space and releases heat in a warm space. That is, in the heat pump, heat energy is transferred in a direction opposite to the natural heat transfer direction. To this end, the heat pump uses a small amount of external energy to transfer energy from the heat source to the heat sink.

Air conditioning, refrigerators and air conditioning (HVAC: Heating Ventialating and Air Conditioning) are typical examples of heat pumps. In addition, heat pumps include water purifiers, dryers, washing machines, and vending machines that provide cold/hot water.

In a conventional heat pump, when the compression amount per unit time of a variable-capacity compressor such as an inverter compressor is increased, there is a problem in that the efficiency between the high pressure and the low pressure is increased and the efficiency is lowered.

Application No. KR 10-2013-0084665 (US 9,372,015 B2) Application No. KR 10-2016-7026740 US 2016/0370044 A1) Application No. KR 10-2007-0084960 US 2011/0041523 A1 US 7,010,927 B2 US 9,738,138 B2 US 2017/0059219 A1 US 2017/0115043 A1 WO 2018/025900 A1

It is derived to solve the problems of the prior art of the present invention. That is, it is intended to provide a heat pump control method that can improve the efficiency by preventing the gap between the high pressure and the low pressure from becoming larger during the operation of the heat pump.

In the heat pump control method according to the present invention, a circuit including a compressor, a condenser, an expansion valve (hereinafter referred to as "first expansion valve") and an evaporator is connected through a closed refrigerant line, and the condenser fan, the evaporator fan and the circuit In the control method of a heat pump including a refrigerant (charge amount) control means (hereinafter referred to as "second expansion valve") for charging refrigerant or recovering refrigerant from the circuit, the second expansion valve recovers the refrigerant from the circuit A recovery valve, a storage space for storing the refrigerant, and a charging valve for filling the refrigerant with the circuit are configured to be connected in series in this order, and the second expansion valve is installed between the inlet of the first expansion valve and the low pressure line. , Setting a target condensation temperature; When the condensing temperature is lower than the target condensing temperature, the refrigerant regulating means filling the circuit with the refrigerant; When the condensation temperature is higher than the target condensation temperature, the refrigerant refrigerant control means recovering the refrigerant from the circuit; Including, a certain amount of refrigerant passes through the second expansion valve in daily operation; It is characterized by doing.

At this time, when the power supply required to control the second expansion valve is started, controlling the opening of the recovery valve (vvd) to be smaller than the charging valve (vvc) to empty the refrigerant in the storage space; After performing the step, reducing the opening of the filling valve (vvc) when the set initialization step time (s_init) has elapsed, or the high pressure is higher than the target high pressure; It is preferable to further include.

In addition, the refrigerant charging step and the recovery step is one of the valve of the charge valve (vvc) and the recovery valve (vvd) to fix the opening degree (or the opening degree is a fixed valve), control to control the other valve; It is preferable to further include.

In addition, the first expansion valve may include any one of a capillary tube, a thermally sensitive expansion valve (TXV), a pressure sensitive expansion valve (PXV), or an electronic expansion valve (EEV); It is preferred.

In addition, the filling valve (vvc) and the recovery valve (vvd) includes an orifice for bypassing the refrigerant; It is desirable to do.

The condenser fan speed control method of the heat pump according to the present invention (including the supercooling measuring means and the refrigerant filling amount adjusting means) is the target condensing temperature (eg, t_tc = outside temperature +10 °C), the target supercooling (eg, t_sc =5°C) and setting the initial speed of the fan (eg, fspd=95%); Measuring a condensation temperature (tc) and a supercooling degree (sc); Controlling the fan speed fspd to achieve a target subcooling sc; And controlling the refrigerant filling amount adjusting means to achieve a target condensation temperature (t_tc). It is preferred to include.

At this time, setting a reference fan speed (eg, d_fspd=95%) having a predetermined constant value; Further comprising, if the fan speed is greater than or equal to the reference fan speed (fspd >= d_fspd ), and the condensing temperature is less than the target condensing temperature (tc <t_tc ), the largest value that satisfies the condition fspd <d_fspd is the fan. Setting the speed fspd; If the fan speed is less than the reference fan speed (fspd <d_fspd), controlling the fan speed fspd to achieve a target supercooling degree t_sc and controlling a refrigerant charge amount to achieve a target condensation temperature t_tc step; And if the fan speed is greater than or equal to the reference fan speed (fspd >= d_fspd), controlling the condensation temperature (tc) (by adjusting the refrigerant charge amount) to achieve a target supercooling degree (t_sc); It is preferable that the method is a condenser fan speed control method.

The condenser fan speed control method of the heat pump according to the present invention (including the supercooling measurement means and the refrigerant filling amount adjustment means) comprises: setting the fan speed to a saturation speed (eg, fspd=100%) (s30); Setting a target condensation temperature and a target supercooling degree (eg, t_sc=5°C) (s31); Controlling the fan speed fspd to achieve the target subcooling t_sc (s32); Measuring the condensation temperature (tc) and supercooling (sc) after the speed control step (s32) (s33); If the measured condensation temperature is greater than or equal to the target condensation temperature (ie, tc >= t_tc ), controlling the target condensation temperature (t_tc) to be achieved by lowering the condensation temperature (tc) by the refrigerant filling amount control means (s34). ; And if the measured condensation temperature is less than the target condensation temperature (ie, tc<t_tc), increasing the condensation temperature (tc) with the filling amount adjusting means to control the target condensation temperature (t_tc) to be achieved (s35); It is preferred to include.

At this time, when the fan is operating at a saturation speed, if the measured subcooling is less than the target subcooling (ie, sc <t_sc ), the target subcooling ( t_sc) (s44a); And if the measured supercooling is less than the target supercooling (ie, sc <t_sc ), lowering the condensation temperature (tc) with the refrigerant filling amount control means to achieve the target supercooling (t_sc); It is preferable to further include.

According to the heat pump control method of the present invention, there is an effect of providing a heat pump capable of improving the efficiency by preventing the gap between the high pressure and the low pressure from becoming larger during operation of the heat pump.

1 is an example of a ph diagram according to the prior art.
2 is a diagram for understanding the first to fourth controls of the present invention.
3 is an example of a ph diagram according to the present invention.
4 is an example of a control procedure of the present invention.
5 is an example of listing the types of control procedures of the present invention.
6 is an example of a heat pump circuit suitable for the present invention.
7 is another example of a heat pump circuit suitable for the present invention.
8 is another example of a heat pump circuit suitable for the present invention.
9 is another example of a heat pump circuit suitable for the present invention.
10 is an example showing a high-pressure waveform according to the present invention.
11 is an example of a condenser fan speed control method according to the present invention.
12 is another example of a condenser fan speed control method according to the present invention.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. At this time, it should be noted that the same components are denoted by the same reference numerals in the accompanying drawings. The spatially relative terms "below", "beneath", "lower", "above", "upper", etc., are as shown in the figure. It can be used to easily describe the correlation between components and other components. Also, in this specification, the term "pressure" may be interpreted as "the temperature at which the refrigerant boils, the condensation temperature, or the evaporation temperature."

The terminology used herein is for describing the embodiments and is not intended to limit the present invention. In the present specification, the singular form also includes the plural form unless otherwise specified in the phrase. As used herein, "comprises" and/or "comprising" refers to the components, steps and/or actions mentioned, excluding the presence or addition of one or more other components, steps and/or actions. I never do that.

In addition, the terms or words used in the specification and claims described below should not be interpreted as being limited to ordinary or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical spirit of the present invention. In addition, detailed descriptions of well-known structures and functions that are determined to unnecessarily obscure the subject matter of the present invention are omitted.

In the following description, it will be described using an ideal heat pump unless otherwise specified for convenience.

The object of the present invention is to improve the performance (COP) of the heat pump while making the heat exchange amount of the heat exchanger the same. To this end, a method capable of individually controlling the condenser temperature and the evaporator temperature is required.

<Core Concept Description>

The air heat exchanger can calculate the heat exchange amount as Q = c·m·dT. Here, there are many combinations of m and dT that make Q equal. In the above equation, m can be interpreted as air volume, air weight, wind speed, heat exchanger fan speed, and fan power consumption. Where c will be the specific heat of the air or a proportionality coefficient. And the temperature difference dT (= air temperature before passing through the heat exchanger-air temperature after passing) can be changed by the temperature difference between the boiling temperature of the refrigerant inside the heat exchanger and the incoming air.

In more detail, if the temperature of the heat exchanger (the temperature at which the refrigerant boils in the heat exchanger) and the air temperature are the same, heat exchange does not occur. One of the methods of reducing the temperature difference dT is to reduce the difference between the air temperature entering the heat exchanger and the refrigerant boiling temperature (hereinafter, “heat exchange temperature”) inside the heat exchanger. For this, it is necessary to control the heat exchanger temperature by changing the pressure inside the heat exchanger, which is obviously related to the power consumption of the compressor.

In the case of a passenger car air conditioner, the electric compressor capacity is about 3.5 kW, and the heat exchanger fan is about 150 W. Therefore, while maintaining the same heat exchange amount (Q = c·m·dT) of the heat exchanger, increasing the fan power consumption and reducing the power consumption of the compressor will improve the efficiency of the air conditioner. For this, it is necessary to individually control the condensation temperature and evaporation temperature.

<Element technical description>

Hereinafter, with reference to Figures 1 and 2 will be described with respect to the element technology for individually adjusting the condensation temperature and evaporation temperature.

Hereinafter, a process of injecting refrigerant into a general air conditioning system will be described. When the air conditioner piping installation is completed, the inside of the piping is vacuumed with a vacuum pump. When the inside of the pipe becomes vacuum, connect the refrigerant cylinder (on the electronic scale) outside the air conditioner and the low pressure line, start the compressor, and open the valve of the external refrigerant cylinder to charge the refrigerant with a heat pump from the external refrigerant cylinder. Then, when the refrigerant of the set weight is charged, the refrigerant charging is stopped. Then, high pressure and low pressure are properly formed. For example, the first cooling cycle (81)-(82)-(83)-(84). Here, it can be seen that when the refrigerant is charged (hereinafter referred to as "first control"), both the high pressure (HP) and the low pressure (LP) increase (1) from vacuum to low pressure and from vacuum to high pressure. Conversely, it can be seen that when the refrigerant is recovered (hereinafter referred to as "second control"), both the high pressure (HP) and the low pressure (LP) decrease (2) from low pressure to vacuum, high pressure to vacuum.

In other words, if the refrigerant circuit is additionally charged with the circuit low pressure from the outside in a cooling circuit in which high pressure and low pressure are properly formed, the added refrigerant is not only in the low pressure (until the high pressure and the low pressure are stabilized). It will move partly under high pressure. Here, it can be seen that when the refrigerant is charged, both the high pressure (HP) and the low pressure (LP) increase (1). Conversely, when the refrigerant is recovered, it is natural that both the high pressure (HP) and the low pressure (LP) decrease (2).

When the first cooling cycle (81)-(82)-(83)-(84) is formed, further closing the expansion valve or increasing the amount of refrigerant compression per unit time of the compressor (hereinafter, the difference between the high pressure and the low pressure increases) 3rd control"), the high pressure (HP) increases and the low pressure (LP) decreases (3) to become the second cooling cycle (91)-(92)-(93)-(94). In addition, when the expansion valve is further opened or the refrigerant compression amount per unit time of the compressor is reduced in the state in which the second cooling cycles 91, 92, 93, and 94 are formed, the difference between the high pressure and the low pressure decreases. "4th control"), the high pressure (HP) decreases and the low pressure (LP) increases (4) to become the first cooling cycle (81)-(82)-(83)-(84).

When the first control (1) or the second control (2), both the high pressure and the low pressure increase (UU) or decrease (DD), and the third control (3) or the fourth control (4) increases the high pressure ( When u), the low pressure decreases (d), and when the high pressure decreases (d), the low pressure increases (u). Therefore, when the control in which the two pressures move in one direction and the control in the opposite direction is combined, the pressure on the other side can be adjusted while maintaining the pressure on one side.

For example, if the first control 1 and the third control 3 are performed simultaneously or sequentially, the high pressure may increase and the low pressure may be offset, so that it does not fluctuate. (Hereinafter, "the step of increasing the condensation temperature while maintaining the evaporation temperature") In addition, if the first control 1 and the fourth control 4 are performed simultaneously or sequentially, the low pressure increases, and the high pressure is offset, so that it does not fluctuate. Can. (Hereinafter, "the step of raising the evaporation temperature while maintaining the condensation temperature") Also, if the second control (2) and the third control (3) are performed simultaneously or sequentially, the low pressure decreases and the high pressure cancels out and does not fluctuate. Can. (Hereinafter, "the step of lowering the evaporation temperature while maintaining the condensation temperature") Also, if the second control (2) and the fourth control (4) are performed simultaneously or sequentially, the high pressure decreases and the low pressure cancels out and does not fluctuate. Can. (Hereinafter, "the step of lowering the condensation temperature while maintaining the evaporation temperature") At this time, it is desirable to maintain the supercooling degree and the superheating degree as much as possible.

When the third control (3) and the fourth control (4) are performed, the refrigerant circulation amount per unit time may be adjusted without changing the high pressure and the low pressure. More specifically, in the third control, the amount of refrigerant compression per unit time of the compressor is further increased to further increase the difference between high pressure and low pressure, and in the fourth control, the expansion valve is further opened to further reduce the difference between high pressure and low pressure. However, the amount of refrigerant circulating in the circuit per unit time can be further increased. On the other hand, it is natural that the amount of refrigerant circulating in the circuit can be further reduced by changing the objects of the third control and the fourth control. (Hereinafter, "Step of adjusting the heat exchange amount while maintaining the condensation temperature and evaporation temperature")

In the above, a method of individually controlling high pressure and high pressure has been described.

Hereinafter, an embodiment (air-conditioning cooling mode) of controlling the evaporation temperature to be higher in the heat pump according to the present invention will be described with reference to FIGS. 2 to 4. 4 is an example of a procedure for controlling the evaporation temperature of the evaporator to be higher.

4, the control procedure 100 is an example in which the fourth control and the first control are successively performed twice. When the fourth control is performed in the initial state (L0), the high pressure goes down, and the low pressure goes up to the state (L1). As desired, the low pressure increased and the evaporation temperature became higher, but the high pressure lowered and the condensation temperature became lower than the target condensation temperature (HP_t). When the first control is performed here, the refrigerant is charged, and both the high pressure and the low pressure rise, and the state (L2) is reached. That is, the evaporation temperature of the low pressure is further increased to become closer to the target evaporation temperature LP_t, and the high pressure maintains the target condensation temperature HP_t. State L3 and state L4 show that the fourth control and the first control are sequentially repeated once more (in other words, the step of increasing the evaporation temperature while maintaining the condensation temperature is performed once more). Then, the low pressure rises along (LP_rise) to reach the target low pressure (LP_t). In the control procedure 100, the first control may be referred to as "step of filling the refrigerant", "step of increasing the evaporation temperature" and "step of adjusting to maintain the target temperature (HP_t) of the condenser". Further, the fourth control may be referred to as a “step of increasing the evaporation temperature”.

In FIG. 4, the control procedure 101 uses the fourth control and the first control in the same manner as the control procedure 100, but is the case in which the first control is performed first. When the first control is performed in the initial state (L0a), the refrigerant is charged, so that both the high pressure and the low pressure rise and become the state (L1a). As desired, the low pressure increased and the evaporation temperature became higher, but the high pressure also increased and the condensation temperature became higher than the target condensation temperature (HP_t). Here, when the fourth control is performed, the high pressure is lowered, and the low pressure is raised to the state (L2a). That is, the evaporation temperature of the low pressure is further increased to become closer to the target evaporation temperature LP_t, and the high pressure maintains the target condensation temperature HP_t. State L3a and state L4a show that the first control and the fourth control are sequentially repeated one more time (in other words, the step of increasing the evaporation temperature while maintaining the condensation temperature is performed once more). Then, the low pressure rises along (LP_rise) to reach the target low pressure (LP_t). In the control procedure 101, the first control may be referred to as “step of filling the refrigerant” and “step of increasing the evaporation temperature”. In addition, the fourth control may be referred to as "steps of adjusting to maintain the target temperature HP_t of the condenser" and "steps of increasing the evaporation temperature".

In the above, a method of achieving the target evaporation temperature while maintaining the condensation temperature of the condenser has been described in detail when the target evaporation temperature is set higher than the current evaporation temperature.

In FIG. 5, the control procedure 200 sets a target condensation temperature (HP_t) of the condenser higher than the current condensation temperature (HP_0) and achieves the target condensation temperature (HP_t) while maintaining the evaporator's evaporation temperature (LP_t). This is an example of showing. Here, the first control for filling the refrigerant and the third control for increasing the difference between the high pressure and the low pressure were used (in other words, a step of increasing the condensation temperature while maintaining the evaporation temperature was performed). In the control sequence 200, the first control may be referred to as “step of filling the refrigerant” and “step of increasing the condensation temperature”. In addition, the third control may be referred to as "step of adjusting to maintain the evaporator target temperature LP_t" and "step of increasing the condensation temperature".

In FIG. 5, the control procedure 150 sets the target evaporation temperature LP_t of the evaporator lower than the current evaporation temperature LP_0, and achieves the target evaporation temperature LP_t while maintaining the condenser condensation temperature HP_t. This is an example of showing. Here, the second control for recovering the refrigerant and the third control for increasing the difference between the high pressure and the low pressure were used (in other words, a step of lowering the evaporation temperature while maintaining the condensation temperature) was performed. In the control sequence 150, the second control may be referred to as “recovering refrigerant”, “lowering evaporation temperature” and “adjusting to maintain the target condensation temperature HP_t of the condenser”. Further, the third control may be referred to as a “step of lowering the evaporation temperature”.

In FIG. 5, the control procedure 250 sets the target condensation temperature HP_t of the condenser lower than the current condensation temperature HP_0 and achieves the target condensation temperature HP_t while maintaining the evaporator temperature LP_t. This is an example of showing. Here, the second control for recovering the refrigerant and the fourth control for reducing the difference between the high pressure and the low pressure were used (in other words, a step of reducing the condensation temperature while maintaining the evaporation temperature) was performed. In the control procedure 250, the second control may be referred to as “recovering the refrigerant” and “reducing the condensation temperature”. In addition, the fourth control may be referred to as "steps of adjusting to maintain the evaporator target temperature LP_t" and "steps of lowering the condensation temperature".

When a conventional air conditioner is operated to some extent and the cooling load is reduced, the outdoor unit and the indoor unit fan rotate below the maximum speed. In addition, since the conventional air conditioner cannot individually control the evaporation temperature and the condensation temperature, it is impossible to increase the efficiency (COP) while maintaining the same load (heat exchange amount).

According to this embodiment, it is possible to lower the condensation temperature of the condenser without changing the evaporation temperature of the evaporator. Therefore, when the cooling load is smaller than the maximum rating, the heat exchange amount (Q = c·m·dT) of the outdoor heat exchanger is kept the same, while reducing the power consumption of the compressor and increasing the power consumption of the outdoor fan, the performance of the air conditioner (COP). Can increase. Here, increasing the power consumption of the outdoor unit fan means "to increase the rotation speed of the outdoor unit fan." Or, it can be interpreted as "the weight of air transported per unit time is increased." In addition, reducing the power consumption of the compressor does not separately control the compressor, and it is natural that the power consumption of the compressor is reduced when the difference between the high pressure and the low pressure is reduced, as in the control procedures 100 and 250.

In addition, the air conditioner without the conventional refrigerant (charge amount) control means is operated to some extent, and when the cooling load is reduced, the indoor unit fan rotates at a low speed. According to this embodiment, even if the evaporation temperature of the evaporator is changed, the condensation temperature of the condenser does not change. Therefore, when the cooling load is less than the maximum rating, while maintaining the same heat exchange amount (Q = c·m·dT) of the indoor heat exchanger, the performance of the air conditioner is reduced by reducing the power consumption of the compressor and increasing the power consumption of the indoor fan (COP) Can increase. At this time, the refrigerant compression volume per second of the compressor is reduced. However, because the low pressure has increased, the amount of compressed refrigerant once increases, and the amount of refrigerant compressed per second does not decrease proportionally as the compressed volume decreases.

In order to increase the efficiency of the heat pump according to the present invention, the power consumption of the compressor must be reduced, and the power consumption of the heat exchanger fan must be increased. In the case of the indoor fan, it is desirable to increase it so that a person does not feel uncomfortable. On the other hand, when considering energy saving, it is preferable that the maximum power consumption of the indoor heat exchanger fan is the maximum rated power consumption of the fan. In the case of a car, a person may not be able to feel the noise of the fan due to the inflow of external noise due to vehicle operation. In addition, since there are people who are sensitive to noise and people who are insensitive, it is difficult to set the power consumption to a single value by taking the power consumption of the fan starting to feel uncomfortable. Therefore, when the user inputs a predetermined power consumption when the vehicle is stopped, it is preferable to set the power consumption of the fan starting to feel discomfort for each vehicle driving condition by referring to the input value.

In addition, in the case of the fan of the outdoor unit, it is preferable to increase the noise of the outdoor unit into the room so that a person does not feel uncomfortable. If soundproofing is good between indoor and outdoor, it is natural that the fan of outdoor unit can be driven with the maximum power allowed.

In the above description, it can be seen that, in the heat pump according to the present invention, when the target temperature increases, the (100) (200) needs to charge the refrigerant in the cooling circuit. In addition, it can be seen that when the target temperature decreases (150) (250), the refrigerant must be recovered from the cooling circuit.

It is natural that the heat pump control concept of the present invention can be applied to heating. Therefore, the step of setting the target evaporation temperature of the air conditioner is preferably interpreted as "the step of setting the heat exchange temperature of the internal heat exchanger with reference to the heat exchange load of the indoor heat exchanger." Then, the step of setting the target condensation temperature of the air conditioner is preferably interpreted as "the step of setting the heat exchange temperature of the external heat exchanger with reference to the heat exchange load of the outdoor heat exchanger."

Hereinafter, an example of a heat pump 600 suitable for the present invention will be described with reference to FIG. 6.

The heat pump 600 is connected through a refrigerant line in which a “circuit” including a compressor C, a condenser HEX_C, an expansion valve EXV, and an evaporator HEX_E is sealed. Then, the refrigerant storage tank RS1 is installed in parallel with the expansion valve EXV. Between the inlet of the expansion valve (EXV) and the inlet of the tank (RS1), a recovery valve (vvd) for recovering refrigerant in a “circuit” is installed. And between the expansion valve (EXV) outlet and the tank (RS1) outlet is provided with a filling valve (vvc) for filling the refrigerant with a "circuit". It is preferable that the refrigerant storage tank RS1 has a gas-liquid separation function.

Here, the refrigerant storage tank (RS1), the recovery valve (vvd) and the charging valve (vvc) charges the refrigerant in the "circuit" or recovers the refrigerant from the "circuit" (hereinafter, "refrigerant (charge amount) ) Adjustment means").

Hereinafter, a method of charging the refrigerant when the heat pump 600 is installed will be described. First, after installing the heat pump 600 piping, all the valves (EXV) (vvd) (vvc) are opened, and the inside of the "circuit" and the refrigerant storage tank (RS1) is vacuumed using a vacuum pump. Then, the recovery valve (vvd) is completely closed. When the refrigerant cylinder outside the heat pump 600 is connected to the inlet of the compressor C, the compressor C is operated, and the valve of the external refrigerant cylinder is opened, the refrigerant is charged from the external refrigerant cylinder to the heat pump 600. When the prescribed amount of refrigerant is charged, the external refrigerant cylinder valve is completely closed. With the above procedure, it is possible to implement condensation temperature and evaporation temperature, such as a heat pump without a conventional refrigerant (charge amount) control means.

Hereinafter, a second control in which the refrigerant is recovered from the “circuit” of the heat pump 600 and stored in the refrigerant storage tank RS1 will be described. First, when the refrigerant recovery valve (vvd) is opened, the high pressure of the "circuit" is high and the inside of the storage tank RS1 is vacuum, so the condensed refrigerant is recovered from the "circuit" to the storage tank RS1 and expanded. When a certain amount of refrigerant is recovered into the storage tank RS1, the refrigerant may not be recovered any more. At this time, if the refrigerant charge valve (vvc) is opened slightly to discharge the gas inside the storage tank (RS1), the refrigerant recovery continues. On the other hand, when opening the refrigerant charge valve (vvc), it is also preferable to close the expansion valve (EXV) a little so that the amount of refrigerant flowing into the evaporator (HEX_E) is the same as before operating the charge valve (vvc).

Hereinafter, the first control for filling the "circuit" of the heat pump 600 with the refrigerant will be described. When the filling valve vvc is opened (slightly) in the closed valve vvd, the gas refrigerant inside the refrigerant storage tank RS1 is moved by the suction force of the compressor to be charged to the "circuit". Finally, the refrigerant is charged into the "circuit" until the pressure in the low pressure line and the pressure inside the refrigerant storage tank (RS1) are equal.

The third control and the fourth control are the same as those in the first embodiment, and detailed descriptions thereof will be omitted.

As described above, the first control to the fourth control are possible in the heat pump 600. Therefore, it is natural that the condensation temperature and the evaporation temperature can be individually controlled by driving the heat pump 600 using the procedure described in this embodiment.

On the other hand, when the refrigerant charge valve (vvc) and the recovery valve (vvd) are both closed and a long time passes, the refrigerant in the refrigerant storage tank (RS1) evaporates, so that the pressure in the storage tank (RS1) may be higher than the internal pressure of the condenser. Then, when recovering the refrigerant, the refrigerant recovery time may take longer than usual. Therefore, rather than locking both the refrigerant charge valve (vvc) and the recovery valve (vvd) normally, most of the refrigerant circulating in the "circuit" (eg, 98% refrigerant circulation) circulates through the expansion valve EXV, It is preferable that a portion of the circulating refrigerant (eg, 2% refrigerant circulation amount) is always allowed to pass through the storage tank RS1, so that the pressure inside the storage tank RS1 becomes a pressure between high pressure and low pressure.

The heat pump 700 of FIG. 7 illustrates a case where the refrigerant filling valve vvc is installed between the storage tank RS2 and the compressor C inlet. The storage tank (RS2) of the heat pump 700 is preferably installed in the outdoor unit. In addition, since the refrigerant storage tank RS1 is installed in parallel with the expansion valve EXV in the heat pump 600, it is preferable that the storage tank RS1 is installed in the indoor unit. The heat pump 700 may be preferable when the indoor unit space is narrow, such as a car.

Hereinafter, an example of a heat pump 800 suitable for the present invention will be described with reference to FIG. 8.

The heat pump 800 is a compressor (C), a condenser (HXE_C), a mechanical first expansion valve (EXV1) and an evaporator (HEX_E) is connected through a closed refrigerant line to constitute a heat pump "circuit". In addition, an electronic second expansion valve EXV2 is installed in parallel with the expansion valve EXV1. The amount of refrigerant supplied to the evaporator HEX_E is controlled by the first expansion valve EXV1 and the second expansion valve EXV2. Here, the second expansion valve is a recovery valve (vvd) for recovering refrigerant, a refrigerant storage tank (RS3), and a charging valve (vvc) for charging the refrigerant connected in series. The second expansion valve EXV2 may be formed of one body or may be formed by assembling the parts.

The second expansion valve EXV2 serves to expand the refrigerant and to charge the refrigerant in the "circuit" or to recover the refrigerant in the "circuit" (hereinafter, "refrigerant (charge amount) control means"). At this time, the maximum amount of refrigerant that can be stored in the storage tank (RS3) is preferably less than 1/2 of the total amount of refrigerant present in the heat pump 800. Here, the mechanical first expansion valve EXV1 may be a capillary tube or a thermally sensitive expansion valve TXV.

Hereinafter, a preferred driving example of the heat pump 800 will be described.

First, the refrigerant recovery valve (vvd) inside the second expansion valve (EXV2) is completely closed, and the refrigerant charging valve (vvc) is completely opened. And the compressor is driven with the maximum design power consumption. Then, the design pressure at which the difference between the high pressure and the low pressure becomes maximum is formed. At this time, all of the refrigerant supplied to the evaporator (HEX_E) flows through the first expansion valve (EXV1).

Hereinafter, a method of recovering the refrigerant will be described. Of the recovery valve (vvd) and the charging valve (vvc) so that the amount of refrigerant flowing into the refrigerant storage tank (RS3) through the recovery valve (vvd) inside the second expansion valve is greater than the amount of refrigerant flowing through the charging valve (vvc) Adjust the opening degree. Then, the amount of refrigerant stored in the storage tank RS3 increases. (How to recover refrigerant from the circuit)

Hereinafter, a method of filling the refrigerant will be described. Of the recovery valve (vvd) and the charging valve (vvc) so that the amount of refrigerant flowing out through the charging valve (vvc) inside the second expansion valve is greater than the amount of refrigerant flowing into the refrigerant storage tank (RS3) through the recovery valve (vvd). Adjust the opening degree. Then, the amount of refrigerant stored in the storage tank (RS3) is reduced. (How to charge refrigerant in the circuit)

Reducing the pressure difference between high pressure and low pressure while maintaining the heat exchange amount (Q = c·m·dt) in the heat exchanger controls the amount of refrigerant stored in the second expansion valve (EXV2) [refrigerant (charge amount) control function] It is desirable to do so. And, it is preferable to control the amount of refrigerant supplied to the evaporator (HEX_E) with the amount of refrigerant passing through the recovery valve (vvd), the storage tank (RS3) and the filling valve (vvc) (expansion valve function).

In the case of lowering the high pressure, for example, when lowering (92)-(93) to (82)-(83) in FIG. 1, first, increase the power consumption of the condenser fan to increase the supercooling degree (while "larger"). Concept comprising a), it is preferable to achieve by recovering the refrigerant with the refrigerant (charge amount) control means. This is because when the refrigerant is recovered, the condensation temperature decreases and the supercooling degree decreases (see FIGS. 1 (92)-(93) and (82)-(83)).

In case of increasing the low pressure (e.g., (14)-(11) in FIG. 3 is increased to (14b)-(11b)), first increase the power consumption of the evaporator fan to increase the superheat degree (while "larger") Concept comprising a), it is preferable to achieve by charging the refrigerant with the refrigerant (charge amount) control means. This is because it is desired to prevent liquid compression from occurring in the compressor while the low pressure is changing.

When the air conditioner without the conventional refrigerant (charge amount) control means is operated to some extent, when the cooling load is reduced, the indoor unit fan rotates at a low speed. And, at this time, the condensation temperature of the condenser and the evaporation temperature of the evaporator could not be adjusted.

According to this embodiment, it is possible to increase the evaporation temperature of the evaporator while maintaining the condensation temperature of the condenser. In addition, it is possible to lower the condensation temperature of the condenser while maintaining the evaporation temperature of the evaporator. That is, it is possible to improve the efficiency of the heat pump by reducing the pressure difference between high pressure and low pressure. Therefore, when the cooling load is less than the maximum rating, the heat exchanger performance (COP) is reduced by reducing the power consumption of the compressor and increasing the power consumption of the heat exchanger fan while maintaining the same heat exchange amount (Q = c·m·dT) of the heat exchanger. ) Can be improved. Here, increasing the power consumption of the heat exchanger fan means "to increase the rotational speed of the heat exchanger fan." Or, it can be interpreted as "the weight of air transported per unit time is increased." And reducing the power consumption of the compressor does not control the compressor separately, and it is natural that the power consumption of the compressor is reduced when the difference between the high pressure and the low pressure is reduced as in the control procedures 100 and 250.

Among the matters to be noted in carrying out the present invention, the first is to perform a good thermal insulation on the refrigerant (charge amount) control means. Medium pressure between high pressure and low pressure is formed in the storage space inside the refrigerant control means. When the liquid refrigerant flows into the storage space through the recovery valve (vvd), part of the phase changes to gas, and the ratio of the liquid and gas varies depending on the storage space pressure. [Refer to Figs. 1, (93)-(94)] If the insulation is not good, if the heat penetrates from the outside or the heat flows out, the proportion of the liquid gas will change, which may result in an undesired liquid-gas ratio. Because. And second, attention should be paid to the selection of the physical location where the return valve (vvd) and the filling valve (vvc) are connected to the storage space. This is because if the location selection is wrong, the operation is performed so that the refrigerant flows out of the storage space, but the refrigerant does not flow out and may be stuck in the storage space.

The heat pump 900 of FIG. 9 removes the first expansion valve EXV1 from the heat pump 800 of FIG. 8, changes the refrigerant storage tank RS3 into a storage tank RS4 capable of gas-liquid separation, and the gas liquid The gas inside the separator (RS4) has been modified so that it can be injected into the compressor (C) (in a broader sense the term "supply"). The method of charging and recovering the refrigerant is possible on the same principle as the heat pump 800, so a detailed description is omitted.

Hereinafter, an example of a method for controlling a heat pump 800 suitable for the present invention will be described with reference to FIGS. 8 and 10.

The configuration of the heat pump 800 of FIG. 8 has been described in detail in the preceding description and is therefore omitted. However, in this embodiment, the first expansion valve (EXV1) is a capillary tube, temperature-sensitive (hereinafter, "TXV"), pressure-sensitive (hereinafter, "PXV"), electronic (hereinafter, "EEV") expansion valve, such as You may use

In this embodiment, TXV is described as the first expansion valve EXV1. Control of the rest of the parts except for the second expansion valve (EXV2) is performed independently. More specifically, the control of the compressor (C), condenser fan (FN_C), supercooling, etc. is managed by an independent controller. In addition, the second expansion valve EXV2 is managed by another independent controller that refers to the condensation temperature (the temperature at which the refrigerant boils at high pressure, hereinafter also referred to as "high pressure"). (Of course, one controller can simultaneously control two independent control routines.)

Hereinafter, an example of a control procedure of the second expansion valve EXV2 that is preferable in the heat pump 800 will be described. For convenience of description, it is assumed that the same amount of refrigerant passes through the two valves when the opening degree of the recovery valve (vvd) and the filling valve (vvc) are the same, and more refrigerant passes through the two valves when the opening degree is large. In practice, it is natural that the pressure difference across each valve may be different from the above assumption.

<Initialization step (s_init)>

When the power supply required to control the second expansion valve EXV2 is started, the opening of the recovery valve vvd is controlled to be smaller than the charging valve vvc to empty the refrigerant in the storage space (s_init). Conduct. As a specific value, for example, the opening of the recovery valve (vvd) is set to 2%, and the opening of the filling valve (vvc) is set to 100%. When the compressor C starts operating, the condensation temperature cv_2 rises.

When the set initialization step (s_init) time has elapsed or the high pressure is higher than the target high pressure, the opening step of the filling valve (vvc) is reduced (eg, from 100% to 2%) to end the initialization step. The target high pressure can be set by setting the difference between the condensing temperature and the temperature of the air exchanging heat with the condenser to be a constant value.

<High pressure control step (hp_ctrl)>

The opening degree of the filling valve vvc is fixed (or a valve having a fixed opening degree is used), and the recovery valve vvd is controlled to achieve a target high pressure. When the opening degree of the recovery valve vvd is greater than that of the charging valve vvc, the refrigerant is recovered from the circuit and stored in the storage space RS3 inside the expansion valve EXV2 (hereinafter, referred to as “refrigerant recovery step”). Conversely, if it is smaller, the refrigerant is charged from the storage space RS3 to the circuit (hereinafter, referred to as “refrigerant charging step”). By measuring the high pressure and comparing with the target high pressure, the target high pressure can be achieved by controlling the recovery valve (vvd). It is natural that it can be implemented with PID, PI, Fuzzy control, etc., which are widely used in industry.

The target high pressure may be achieved by fixing the recovery valve vvd (or using a valve with a fixed opening degree) and controlling the filling valve vvc. This is because the relative opening degree of the two valves determines the filling and recovery of the refrigerant. Here, the opening degree of the fixed valve is determined by "how to distribute the refrigerant to the first expansion valve EXV1 and the second expansion valve EXV2 in daily operation".

When the high pressure fluctuates slightly around the target high pressure due to the charge/recovery of the refrigerant, the TXV will work as well as when there is no charge/recovery of the refrigerant. At this time, it is natural that the opening degree of TXV is proportional to the size of the cooling load. In addition, it is natural that the electronic expansion valve (EEV), which is commonly used for superheat control, works well even when used as the first expansion valve (EXV1).

The total amount of refrigerant charged in the circuit and the difference between high pressure and low pressure are proportional. However, it should be noted that if the circuit has components that can store refrigerant (eg, receiver, accumulator……), it may not be proportional. It is preferable to obtain the maximum amount of refrigerant stored in the second expansion valve EXV2 using the selection criteria of the receiver dryer.

By adding an orifice for bypassing the refrigerant inside the filling valve (vvc) and the return valve (vvd), the orifice serves as a capillary that bypasses the second expansion valve (EXV2), that is, the first expansion valve (EXV1). can do.

And, it is natural that the control method described above can be applied to the heat pump 900 of FIG. 9. At this time, the filling valve (vvc) and the recovery valve (vvd) is preferably an orifice that bypasses the valves inside the valves. In addition, it is preferable that the valves have a minimum opening degree so that they cannot be set below. Here, the orifice and the minimum opening degree serve as a first expansion valve EXV1. That is, the second expansion valve EXV1 also serves as the first expansion valve EXV1. When it is desired to control the superheating degree with the second expansion valve EXV2, it is preferable to simultaneously reduce the opening degree of the filling valve vvc and the recovery valve vvd, and increase them simultaneously.

The target condensation temperature may be adjusted based on the opening degree of the second expansion valve EXV2 in the heat pump 900.

Refrigerant may be used in the refrigerant storage means to cool the compressor (including injection function) by supplying the refrigerant directly to the compressor inlet. At this time, if the flow rate directly supplied from the refrigerant storage means to the compressor is too large, the efficiency is lowered, so it is required to control the refrigerant to flow in an appropriate amount.

This embodiment relates to a condenser fan speed control method (to achieve the target condensation temperature according to the present invention). More specifically, while achieving the target condensation temperature (t_tc), while exchanging the same amount of heat according to the formula Q=c·m·dT, a method of controlling the condenser fan speed to increase the efficiency of the heat pump by lowering the total power consumption will be.

The condenser fan speed control method of this embodiment requires a supercooling degree measurement means and a refrigerant (charge amount) control means.

Hereinafter, a condenser fan speed control procedure will be described.

1) When power is supplied to the fan speed controller, the target condensing temperature (eg, t_tc= 45°C = outside temperature +10°C), the target supercooling rate (eg, t_sc=5°C) and the initial speed of the fan (eg, fspd=95%). Here, it is preferable to set the target condensation temperature t_tc as follows. a) In the formula Q=c·m·dT, the optimal condensation temperature (tc) is set as the target condensation temperature (t_tc). b) The optimum condensing temperature (tc) and the optimum fan speed (fspd) can be obtained by a number of experiments, and the obtained one is the target condensing temperature (t_tc). In both cases, the purpose is to lower the power consumption while exchanging the same amount of heat, and since the condensation temperature is actively controlled to vary dT, it should be considered that the present invention is calculated by the formula Q=c·m·dT. do. And it is natural that a refrigerant (charge amount) control means is required to control the condensation temperature.

After the initial standby time after the power is turned on, it is desirable to start adjusting the fan speed of the condenser.

First, 2) The condensation temperature (tc) and the supercooling degree (sc) are measured. At this time, the condensation temperature (tc) is preferably measured by measuring the pressure of the refrigerant at the outlet of the condenser and the temperature at which the refrigerant boils (bubble point, boiling point, hereinafter referred to as “condensation temperature”). In addition, it is preferable to measure the temperature at the pressure measurement point, and obtain the supercooling degree (sc) as a difference between the “condensation temperature” (tc) and the measured temperature.

And 3) by controlling the fan speed (fspd) to achieve the target supercooling (t_sc).

Meanwhile, 4) while referring to the measured “condensation temperature” (tc), the target condensation temperature (t_tc) is achieved by the refrigerant (charge amount) control means. At this time, it is natural that the target supercooling degree t_sc and the target condensing temperature t_tc can be achieved by independent control of each other.

For example, see FIG. 11, the load is small [eg, when 20 g refrigerant must be exchanged in 1 second (20 g/s)], the supercooling degree (sc) becomes 5°C at 50% of the fan speed (fspd). . And when the refrigerant needs to be exchanged (40 g/s), the supercooling (sc) becomes 5°C at 75% of the fan speed (fspd). And at all sizes of load, the condensation temperature (tc) is the target condensation temperature (t_tc).

The above control procedure is applied when the condenser fan capacity is sufficiently large. That is, it is a preferable control method when designing a new heat pump.

This will be described below with reference to FIG. 12. 12 is an example of a method for controlling a condenser fan according to a load size when using a variable capacity compressor. This is a preferable control method when retrofitting an already installed heat pump.

First, in the prior art without a refrigerant (charge amount) control means, when the compressor compression speed increases, the condensation temperature (o_tc) and the condenser fan speed (o_fspd) rise together. When the heat exchange demand is 20 g/sec of refrigerant, the condenser temperature (o_tc) is 50°C in the prior art. And, the condenser fan speed (o_fspd) is 20%. When exchanging the same amount of heat using the formula Q=c·m·dT to improve efficiency, the condensation temperature (n_tc) is the target condensation temperature (t_tc) 45℃, 5℃ lower than before, and the fan speed (n_fspd) is 50 %, which is 30% higher than before.

If the heat exchange demand (or "compressor speed" in other words) increases, the fan speed (n_fspd) becomes saturated at high loads (eg compressor speed, if the fan is not replaced with a higher capacity when retrofitting). 60~100%) occurs. Since the fan speed cannot be further increased in this section, the target condensation temperature (t_tc) is ignored, and the condensation temperature (tc) is increased to further increase the difference from the external temperature (t_ambient) to maintain the heat exchange demand as before. .

Hereinafter, a condenser fan speed control procedure will be described.

First, 1) a reference fan speed having a predetermined value (eg, d_fspd=95%) is set.

2) Measure the condensation temperature (tc) and supercooling degree (sc). At this time, it is desirable to obtain the degree of supercooling by measuring pressure and temperature.

3) If the fan speed is greater than or equal to the reference fan speed (fspd >= d_fspd ), and the condensing temperature is less than the target condensing temperature (tc <t_tc ), the largest value that satisfies the fspd <d_fspd condition is set as the fan speed (fspd) do. This selects whether the speed of the condenser fan (fspd) is variably controlled to exchange the same amount of heat, or the fan is saturated so that the same amount of heat is exchanged by variably controlling the condensation temperature (tc). It is to do.

4) If the fan speed is less than the reference fan speed (fspd <d_fspd), the fan speed fspd is controlled to control the supercooling degree sc, and the refrigerant charge is controlled to control the condensation temperature tc. [Since the fan speed is not saturated, the fan speed (fspd) is controlled to maintain the same amount of heat exchange. At this time, the condensation temperature (n_tc) is lower than the conventional condensation temperature (o_tc). Also, the fan speed (n_fspd) is higher than the conventional fan speed (o_fspd).]

5) If the fan speed is greater than or equal to the standard fan speed (fspd >= d_fspd), control the condensation temperature (tc) by adjusting [refrigerant (charge amount)] to control the supercooling degree (sc). [Since the fan speed is saturated, the condenser temperature is controlled to maintain the same heat exchange amount. At this time, the condensation temperature (n_tc) is lower than the conventional condensation temperature (o_tc). Also, the fan speed (n_fspd) is higher than the conventional fan speed (o_fspd).]

6) Control procedures 2 to 5 are repeated.

Controlling the condenser fan speed by the above procedures 1 to 6 is to reduce power consumption while exchanging the same amount of heat, and in the present invention, Q= because the active temperature is controlled actively to change dT. It should be considered as obtained by the formula c·m·dT.

This embodiment is another example of a method for controlling a condenser fan speed (to achieve a target condensation temperature according to the present invention). Since this embodiment has been described in more detail with respect to Example 5, redundant description is omitted.

According to KS B ISO 15042, a heat pump performance evaluation standard, the outdoor temperature of dry bulbs in the warm climate is 35℃ for the standard cooling capacity test condition, 43℃ for the maximum cooling capacity test condition, and 21℃ for the minimum cooling capacity test condition. The refrigerant should be charged so that the condenser can exchange heat under the maximum cooling capacity test conditions. The maximum cooling capacity test condition is 14°C higher when viewed from the minimum standard, and 7°C higher when viewed from the standard. This means that the refrigerant is charged more than the optimum amount (corresponding to the above temperature differences) in the minimum and standard standards. This means that the efficiency of the heat pump is improved when the amount of refrigerant is adjusted to be the optimum amount of refrigerant suitable for the outside temperature and load.

If the refrigerant filling amount adjusting means is provided, the heat pump can operate at the optimum refrigerant amount. Then, the condensation temperature in the full load region is lower than in the prior art. It is natural that the condenser fan speed must be increased to achieve heat exchange suitable for the load.

This will be described below with reference to FIG. 12. 12 is an example of the case where the ambient temperature is 35°C.

First, in the case of the prior art without the refrigerant filling amount control means, the condensation temperature is (o_tc), and the condenser fan speed is equal to (o_fspd). More specifically, when the load increases from 20% to 100%, both the condensation temperature (o_tc) and the fan speed (o_fspd) increase linearly. At this time, the subcooling degree sc may be constant at a predetermined value, or may be gradually decreased or gradually increased depending on the slope value of the fan speed o_fspd.

Hereinafter, a method of achieving a supercooling degree and a target condensation temperature when the condenser fan is driven at 100% or less (hereinafter, “the fan speed non-saturation section control method”) will be described. [Refer to FIG. 12, in (n_fspd_2), a section with a load of 20% to 60% and (n_fspd_1)]

When power is supplied to the condenser fan speed controller, it is preferable to set the initial speed (eg, fspd=100%) of the condenser fan (step s30).

Then, a target condensation temperature (eg, t_tc = outside temperature +10°C) and a target supercooling rate (eg, t_sc=5°C) are set (step s31). At this time, the target condensation temperature (t_tc) and the target supercooling degree (t_sc) may be changed according to the outside air temperature (t_amb), humidity, the size of the load, and the condensation temperature fan speed. The experiment can be performed under many conditions, and the target values can be obtained by tabulating values determined to be optimal among them. In addition, the target condensation temperature t_tc may be simply a predetermined higher value than the outside temperature (eg, t_tc = 45°C = outside temperature +10°C). In addition, the target condensation temperature (t_tc) is a predetermined higher value than the outside temperature and increases linearly with the size of the load [eg, t_tc = outside temperature +10 °C + a·cspd, where a=constant, cspd=(load , Eg, compressor speed) ]. [Compressor speed is 60% ~ 100% in (n_tc_2) section, refer to (n_tc_1)]

Case 1) The case where the target condensing temperature t_tc increases linearly when the load increases from 20% to 100% (n_tc_1) will be described. The fan speed at which the condensation temperature tc satisfies the target condensation temperature (n_tc_1) and the subcooling degree tc (eg, t_sc=5°C) may be (n_fspd_1). In the entire load region, the condensation temperature (n_tc_1) according to the present invention is lower than the conventional condensation temperature (o_tc). It is natural that the fan speed (n_fspd_1) of the present invention should be higher than the conventional fan speed (o_fspd) to exchange the same amount of heat because the condensation temperature is lower than that of the prior art. As a result, it is possible to reduce the overall power consumption by exchanging heat of a size suitable for the load, while reducing the power consumption of the compressor (large power consumption) and increasing the power consumption of the condenser fan (small power consumption).

Case 2) In general, it is a method to increase the efficiency in a low load area with a lot of uptime. The target condensing temperature (t_tc) is set higher than the outside temperature by a predetermined value in the entire load area (for example, t_tc = 45°C = outside temperature +10°C). Then, the target supercooling degree (eg, t_sc=5°C) is set. Since the target condensing temperature (t_tc) is a constant value, when the load increases (from 20% to 60%), the target condensing temperature (t_tc) does not increase. Therefore, in order to achieve the target condensing temperature t_tc using the refrigerant amount filling amount adjusting means, and to achieve the target subcooling degree t_sc, and to exchange the amount of heat suitable for the load, it is more than the fan speed n_fspd_1 of the case 1). It is natural that a high fan speed (n_fspd_2) is required.

In the present invention, it is preferable to achieve the target subcooling degree t_sc in cases 1) and 2) with the condenser fan speed control (step s32). And it is preferable to measure the condensation temperature (tc) and the supercooling degree (sc) after the speed control step (s32) (step s33).

If the measured condensation temperature is greater than or equal to the target condensing temperature (ie, tc >= t_tc ), adjusting the target condensation temperature t_tc by lowering the condensation temperature tc using the refrigerant filling amount adjusting means (step s34) ) Is preferred.

And if the measured condensing temperature is less than the target condensing temperature (ie, tc<t_tc), using the refrigerant filling amount adjusting means to increase the condensing temperature (tc) to adjust to achieve the target condensing temperature (t_tc) (step s35) ) Is preferred.

One example of the preferred "fan speed non-saturation section control method" has been described.

Hereinafter, a method of achieving the supercooling degree and the target condensation temperature when the condenser fan is saturated and driven at 100% (hereinafter, “the fan speed saturation section control method”) will be described. [Refer to Fig. 12, section where load is 60% to 100% in (n_fspd_2)]

First, when power is supplied to the condenser fan speed controller, it is preferable to set the initial speed (eg, fspd=100%) of the condenser fan (same as step 40 and step 30).

Then, a target condensation temperature (n_tc_2) and a target supercooling degree (eg, t_sc=5°C) are set (same as step s41 and step 31). At this time, the target condensation temperature (t_tc) and the target supercooling degree (t_sc) may be changed according to the outside air temperature (t_amb), humidity, the size of the load, and the condensation temperature fan speed. The experiment can be performed under many conditions, and the target values can be obtained by tabulating values determined to be optimal among them. In addition, the target condensation temperature (t_tc) is a predetermined value higher than the outside temperature and increases linearly with the size of the load [eg, t_tc=outside temperature +10 °C + a·cspd, where a=constant, cspd=(load Size, eg compressor speed) ]. [Compressor speed is 60% ~ 100% in (n_tc_2) section, refer to (n_tc_1)]

Since the condenser fan speed (fspd) is 100%, the fan speed cannot be increased further. However, when the load becomes smaller (at around 60% of the compressor speed in FIG. 12), the supercooling degree sc at 100% fan speed fspd becomes larger than the target supercooling degree n_tc_2. At this time, it is preferable to control the fan speed (100% or less) (same as step s42 and step 32) to achieve the target supercooling degree (t_sc). Then, the control is changed to the "fan speed non-saturation section control method". And, since the fan speed cannot be increased (when the load is higher than 60% in FIG. 12), it is natural that the fan speed becomes 100% when the fan speed control (step s42) is performed. In the fan speed saturation section, when the load decreases, the supercooling degree increases, and when it increases, the supercooling degree decreases.

After the speed control step (s42), it is preferable to measure the condensation temperature (tc) and supercooling (sc) (same as step s43, step 33).

Case 3) This is a control method when the target condenser temperature (n_tc_2) increases linearly in the section where the fan speed of the condenser is saturated.

If the measured condensation temperature is greater than or equal to the target condensation temperature (ie, tc >= t_tc ), adjusting the condensation temperature (tc) to be the target condensation temperature (t_tc) by using the filling amount adjusting means (step s44, step) 34). On the other hand, if the measured supercooling is less than the target supercooling (i.e., sc <t_sc ), using the refrigerant filling amount adjusting means to lower the condensation temperature (tc) to adjust to achieve the target supercooling (t_sc) (step s44a) ) Is also preferred.

If the measured condensation temperature is less than the target condensation temperature (ie, tc <t_tc), adjusting the condensation temperature (tc) to be the target condensation temperature (t_tc) by using the filling amount adjusting means (step s45, step 35) Same as). On the other hand, if the measured supercooling is less than the target supercooling (ie, sc <t_sc ), adjusting the condensation temperature (tc) by using the refrigerant filling amount adjusting means to achieve the target supercooling (t_sc) (step s45a) ) Is also preferred.

In the above, the “fan speed saturation section control method” has been described. In this specification, the saturation rate was described as 100%, but it is natural that the rate may be different.

The preferred embodiments of the present invention have been described above in detail.

In the present invention, the case where the heat pump is operated in the cooling mode has been described in detail, but it is natural that the concept of the present invention can be used in the heating mode. In the embodiments of the present invention, each of a compressor, an outdoor heat exchanger, and an indoor heat exchanger has been described, but it is natural to those skilled in the art that the present invention may be implemented in plural.

In this specification, it has been described as exchanging heat with air, but it is natural to those skilled in the art that heat exchange with liquid is possible. Therefore, in the present invention, air should be interpreted as a "fluid" containing water. In addition, it is natural that the fan that supplies fluid to the heat exchanger includes a pump that allows liquid to flow through the heat exchanger.

In a car, even when the outside temperature is low (the window is closed, the indoor temperature is high due to the greenhouse effect, or it is raining and dew forms on the window). In addition, the inverter compressor (aka, variable-capacity compressor) has a slightly different high and low pressure at high loads and a high and low pressure at low loads. It is natural that the heat pump heat exchanger according to the present invention can exchange heat with a minimum power consumption in any case.

A conventional air conditioner without a refrigerant (charge amount) control means has a condenser temperature of approximately 60°C when the outside temperature is 35°C and a condenser temperature of approximately 50°C when the outside temperature is 25°C. And when the cooling load was determined, the condenser temperature and the evaporator temperature could not be adjusted. With the heat pump of the present invention, if the evaporator temperature is set to 0°C in the vehicle air conditioner, the superheating degree and supercooling are respectively set to 5°C, and the condenser temperature is decreased from 60°C to 50°C, the performance (COP) is improved by about 30%. . This means that the air conditioning efficiency can be improved by about 30% in SC03 mode (35℃ outside), which is a condition for measuring fuel efficiency of automobile air conditioners in the United States. And, lowering the condenser temperature from 50°C to 40°C improves performance (COP) by about 33%. This means that the air conditioner efficiency can be improved by about 33% in AC17 mode (25°C outside), which is a condition for measuring CO2 emissions by automobile air conditioners in the United States.

Above, the preferred embodiment of the present invention has been described, but this is only an example, and those skilled in the art should understand that various modified embodiments are possible. Therefore, the embodiments of the present invention disclosed in the present specification and drawings merely describe the technical contents of the present invention and provide specific examples to help understanding of the present invention, and are not intended to limit the scope of the present invention.

According to the heat pump control method of the present invention as described above, it is possible to increase the performance (COP) of the heat pump by preventing the increase between the high pressure and the low pressure during the operation of the heat pump, it is very high industrial availability.

In particular, in the case of automobiles, air-conditioning-operated vehicle fuel efficiency is improved, and since the amount of greenhouse gas (CO ₂ ) generated by air-conditioning is reduced, the possibility of industrial use is very high.

HEX_C condenser
HEX_E evaporator
EXV, EXV1, EXV2 expansion valve
C compressor
RS1, RS2, RS3 refrigerant storage tank
FN_C condenser fan
FN_E evaporator fan
vvc refrigerant charge valve
vvd refrigerant recovery valve
t_sc target supercooling
t_tc target condensation temperature
tc condensation temperature
sc supercooling

Claims (11)

A circuit including a compressor, a condenser, an expansion valve (hereinafter referred to as "first expansion valve") and an evaporator is connected through a closed refrigerant line, charging refrigerant to the condenser fan, evaporator fan and the circuit, or recovering refrigerant from the circuit In the control method of the heat pump comprising a refrigerant (charge amount) control means (hereinafter referred to as "second expansion valve"),

The second expansion valve comprises a recovery valve for recovering refrigerant from the circuit, a storage space for storing the refrigerant, and a charging valve for charging the refrigerant with the circuit connected in series in this order,
The second expansion valve is installed between the inlet of the first expansion valve and the low pressure line,

Setting a target condensation temperature;
When the condensing temperature is lower than the target condensing temperature, the refrigerant regulating means filling the circuit with the refrigerant;
When the condensation temperature is higher than the target condensation temperature, the refrigerant refrigerant control means recovering the refrigerant from the circuit; Including,

A certain amount of refrigerant passes through the second expansion valve in daily operation; Heat pump control method. According to claim 1,
When the power supply necessary to control the second expansion valve is started,
Emptying the refrigerant in the storage space by controlling the opening degree of the recovery valve (vvd) to be smaller than the charging valve (vvc); And then
Reducing the opening of the filling valve (vvc) when the set initialization step time (s_init) has elapsed or the high pressure is higher than the target high pressure; Heat pump control method further comprising a. According to claim 1,
In the refrigerant filling step and the recovering step, any one of the filling valve (vvc) and the recovery valve (vvd) fixes the opening degree (or the opening degree is a fixed valve), and controls to control the other valve; Heat pump control method further comprising a. According to claim 1,
The first expansion valve may include any one of a capillary tube, a thermally sensitive expansion valve (TXV), a pressure sensitive expansion valve (PXV), or an electronic expansion valve (EEV); Phosphorus heat pump control method. According to claim 1,
The filling valve (vvc) and the recovery valve (vvd) include an orifice for bypassing the refrigerant; Heat pump control method. In the method of controlling the fan speed of the condenser of the heat pump (including the supercooling measuring means and the refrigerant filling amount adjusting means)

Setting a target condensation temperature (eg, t_tc = outside temperature +10°C), a target supercooling rate (eg, t_sc=5°C) and an initial speed of the fan (eg, fspd=95%);

Measuring condensation temperature (tc) and supercooling degree (sc);

Controlling the fan speed fspd to achieve a target subcooling degree t_sc; And

Controlling the refrigerant filling amount adjusting means to achieve a target condensation temperature (t_tc); Condenser fan speed control method comprising a. The method of claim 6,
Setting a reference fan speed (eg, d_fspd=95%) having a predetermined constant value; Further comprising,

If the fan speed is greater than or equal to the reference fan speed (fspd >= d_fspd) and the condensing temperature is less than the target condensing temperature (tc <t_tc ), the largest value that satisfies the fspd <d_fspd condition is the fan speed (fspd) Setting up;

If the fan speed is less than the reference fan speed (fspd <d_fspd), controlling the fan speed fspd to achieve a target supercooling degree t_sc and controlling a refrigerant charge amount to achieve a target condensation temperature t_tc step; And

If the fan speed is greater than or equal to the reference fan speed (fspd >= d_fspd), controlling the condensation temperature tc (by adjusting the refrigerant charge amount) to achieve a target supercooling degree (t_sc); Condenser fan speed control method comprising a. In the method of controlling the fan speed of the condenser of the heat pump (including the supercooling measuring means and the refrigerant filling amount adjusting means)
Setting the fan speed to a saturation speed (eg, fspd=100%) (s30);
Setting a target condensation temperature and a target supercooling degree (eg, t_sc=5°C) (s31);
Controlling the fan speed fspd to achieve the target subcooling t_sc (s32);
Measuring the condensation temperature (tc) and supercooling (sc) after the speed control step (s32) (s33);
If the measured condensation temperature is greater than or equal to the target condensation temperature (ie, tc >= t_tc ), controlling the target condensation temperature (t_tc) to be achieved by lowering the condensation temperature (tc) by the refrigerant filling amount control means (s34). ; And
If the measured condensation temperature is less than the target condensation temperature (ie, tc<t_tc), increasing the condensation temperature (tc) with the filling amount adjusting means to adjust the target condensation temperature (t_tc) to be achieved (s35); Condenser fan speed control method comprising a. The method of claim 8,
When the fan is running at saturation speed,
If the measured supercooling is less than the target supercooling (ie, sc <t_sc ), lowering the condensation temperature (tc) by the refrigerant filling amount control means to achieve the target supercooling (t_sc) (s44a); And
If the measured supercooling is less than the target supercooling (ie, sc <t_sc ), lowering the condensation temperature (tc) with the refrigerant filling amount control means to achieve the target supercooling (t_sc); Condenser fan speed control method further comprising a. The method according to any one of claims 6 to 9,
A condenser fan controller using the method;
The method according to any one of claims 6 to 9,
A heat pump using the method;

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