JP2011027372A - Refrigerating cycle device and heat pump water heater - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a refrigerating cycle of high efficiency under operating conditions covering a wide range. <P>SOLUTION: This refrigerating cycle device is configured by successively connecting a compressor communicating a suction chamber and a back pressure chamber by a bypass pipe, a heater, an expansion valve, and an evaporator, and further has: an electric valve disposed in the bypass pipe for controlling a pressure in the back pressure chamber to adjust refrigerant flow; an evaporation temperature sensor for detecting an evaporation temperature by the evaporator; a sensor for detecting the information to determine a discharge pressure from the compressor; and a control section for controlling an opening of the electric valve on the basis of the information from the temperature sensor and the sensor. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a refrigeration cycle apparatus, and more particularly to a back pressure control structure that adjusts the pressure in a back pressure chamber.

  In the scroll compressor, a force for separating the two scrolls from each other is generated by the high-pressure fluid in the compression chamber formed by the fixed scroll and the orbiting scroll. At this time, in order to prevent the orbiting scroll from being pulled away from the fixed scroll, a back pressure chamber serving as an intermediate pressure between the discharge pressure and the suction pressure is provided on the back side of the orbiting scroll, that is, the anti-fixed scroll side. Is pressed against the fixed scroll.

  The back pressure is adjusted by a pressure difference control valve (hereinafter referred to as a back pressure control valve) provided in a communication path connecting the back pressure chamber and the suction chamber. Patent Document 1, as a scroll compressor using the back pressure control valve 2 is known.

  Patent document 1 is disclosing the air compressor of a structure which provides a bypass line between a back pressure chamber and a suction inlet, and installs a bypass valve in a bypass line. When the compressor is restarted, the back pressure in the back pressure chamber flows into the suction port via the bypass line and bypass valve, and the pressure in the oil tank is controlled by the control pressure piping, unloading solenoid valve, suction unloader, etc. The suction pressure flows into the suction port, the suction pressure in the suction port decreases slowly and balances with the reduced back pressure state, and the differential pressure between the suction pressure and the back pressure decreases. As a result, it is possible to reduce the pressing force that presses the orbiting scroll toward the fixed scroll, and it is possible to prevent the galling phenomenon between the wrap portions of the scrolls, thereby improving the life and reliability.

  In Patent Document 2, there is a bypass pipe that connects the compression chamber and the back pressure chamber through a back pressure hole, and further connects the back pressure chamber and the discharge pipe, and the bypass pipe is provided with a cupilary pipe and an electromagnetic valve. With this configuration, when the pressure in the back pressure chamber becomes lower than a certain level and the orbiting scroll is separated from the fixed scroll and the efficiency is reduced, the solenoid valve is opened and gas is discharged from the discharge pipe to the back pressure chamber. The pressure of the back pressure chamber is increased by flowing in.

JP-A-6-66270 JP-A-3-258985

  However, Patent Document 1 only discloses a scroll type air compressor, and does not assume a refrigeration cycle. In the scroll type air compressor, the suction pressure and the discharge pressure are both constant, and the back pressure is also constant. Therefore, the back pressure is designed to be an appropriate value. In this regard, as disclosed in paragraph 0010, the bypass valve (13) is a normally closed solenoid valve. Note that the electromagnetic valve can hold only one of the fully open and fully closed states due to its structure. In Patent Document 1, the back pressure is reduced by fully opening the bypass valve (13) for about 4 seconds at the time of starting or restarting. As described above, in Patent Document 1, attention is paid to the problems peculiar to the scroll type air compressor, and the back pressure is released to the suction side by focusing only on the improvement in reliability at the time of starting, but the efficiency is improved during steady operation. The back pressure control is not considered.

  In Patent Document 2, the pressure in the back pressure chamber is determined by an average pressure of the pressure in the compression chamber while the back pressure hole communicates with the compression chamber, and thus there is a pressure fluctuation. If the solenoid valve is opened when the pressure in the compression chamber is low, the gas in the discharge pipe flows back into the compression chamber, increasing the pressure in the compression chamber, leading to an increase in useless compression power and reducing the compressor efficiency.

  An object of the present invention is to realize a highly efficient refrigeration cycle in a wide range of operating conditions.

The object of the present invention is as follows.
A refrigeration cycle apparatus in which a suction section of a compressor in which a suction chamber and a back pressure chamber are communicated by a bypass pipe, a heater, an expansion valve, an evaporator, and a suction section of the compressor are sequentially connected,
A motor-operated valve arranged in the bypass pipe for controlling the pressure of the back pressure chamber and adjusting the flow of the refrigerant;
An evaporation temperature sensor for detecting an evaporation temperature in the evaporator;
A sensor for detecting information capable of obtaining a discharge pressure from the compressor;
Based on the temperature sensor and information from the sensor, a control unit that controls the opening of the motor-operated valve;
Is achieved.

The object of the present invention is as follows.
A compressor discharge unit that connects a suction chamber and a back pressure chamber with a bypass pipe, a heater, an expansion valve, an evaporator, and a tank for storing hot water are sequentially connected to the suction unit of the compressor. Heat pump water heater,
A motor-operated valve arranged in the bypass pipe for controlling the pressure of the back pressure chamber and adjusting the flow of the refrigerant;
An evaporation temperature sensor for detecting an evaporation temperature in the evaporator;
A sensor for detecting information capable of obtaining a discharge pressure from the compressor;
Based on information from the evaporating temperature sensor, the sensor, and the load state detecting means, a controller that controls the opening of the motor-operated valve;
Is achieved.

  According to the present invention, a highly efficient refrigeration cycle can be realized in a wide range of operating conditions.

The longitudinal cross-sectional view of the scroll compressor in this invention. The graph which showed the relationship between back pressure Pb-suction pressure Ps ratio and compressor efficiency. The graph of the approximate expression of discharge pressure Pd / suction pressure Ps and a motor valve opening degree. The graph of the approximate expression of discharge pressure Pd-suction pressure Ps, and an electric valve opening degree. FIG. 5 is a control flowchart when the approximate expression of FIG. 4 is used. FIG. The longitudinal cross-sectional view of the scroll compressor in the 2nd Embodiment of this invention. The graph of the approximate expression of discharge pressure Pd-suction pressure Ps and back pressure Pb-suction pressure Ps ratio. FIG. 8 is a control flowchart when the approximate expression of FIG. 7 is used. FIG. The principal part enlarged view in the 3rd Embodiment of this invention. The unit block diagram of a heat pump water heater.

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

  The first embodiment of the present invention will be described in detail below. FIG. 1 is a longitudinal sectional view of a scroll compressor according to the first embodiment of the present invention. FIG. 2 shows a difference between a back pressure Pb and a suction pressure Ps as a reference differential pressure “back pressure Pb0−suction pressure Ps0”. FIG. 3 is a graph showing the relationship between the “back pressure Pb−suction pressure Ps” ratio expressed by the ratio of the compressor and the compressor efficiency, and FIG. 3 is a graph showing the relationship between the discharge pressure Pd / suction pressure Ps and the motor valve opening degree. FIG. 4 is a graph showing the relationship between the discharge pressure Pd−the suction pressure Ps and the motor valve opening, and FIG. 5 is a control flowchart for determining the motor valve opening from the graph of FIG.

  The scroll compressor 1 includes a swivel wrap 6a having a spiral wrap 6a and a wrap 5c, and a compression mechanism unit 3 having a fixed scroll 5 as main parts, an electric motor 4 for driving the compression mechanism unit 3, and this compression The airtight container 2 which accommodates the mechanism part 3 and the electric motor 4 is provided. A compression mechanism unit 3 is disposed in the upper part of the sealed container 2, and an electric motor 4 is disposed in the lower part. A lubricating oil 13 is stored at the bottom of the sealed container 2.

  The sealed container 2 is configured by welding a lid chamber 2b and a bottom chamber 2c up and down to a cylindrical case 2a. The lid chamber 2b is provided with a suction pipe 2d, and a discharge pipe 2e and a back pressure pipe 2g are provided on the side surface of the case 2a. The inside of the sealed container 2 is a discharge pressure chamber 2f. A compression mechanism 3 and an electric motor 4 are accommodated in the discharge pressure chamber 2f.

  The compression mechanism unit 3 is fixed to the fixed scroll 5 with the bolt 8 by the fixed scroll 5 having the spiral wrap 5c on the base plate 5d, the orbiting scroll 6 having the spiral wrap 6a on the base plate 6b. And a frame 9 that supports the orbiting scroll 6.

  The fixed scroll 5 is provided with a release valve device 15. A revolving scroll 6 is rotatably disposed opposite to the fixed scroll 5.

  A spiral wrap 6a that meshes with the wrap 5c of the fixed scroll 5 is provided on the upper surface of the orbiting scroll 6, and a suction chamber 10 and a compression chamber 11 are formed between the wrap 5c and the wrap 6a.

  The outer peripheral side of the frame 9 is fixed to the inner wall surface of the sealed container 2 by welding. The frame 9 includes a main bearing 9a that rotatably supports the crankshaft 7.

  An eccentric portion 7 b of the crankshaft 7 is connected to the lower surface side of the orbiting scroll 6. An Oldham ring 12 is disposed between the lower surface side of the orbiting scroll 6 and the frame 9. The Oldham ring 12 is mounted in a groove formed on the lower surface side of the orbiting scroll 6 and a groove formed on the frame 9. Yes. The Oldham ring 12 transmits the eccentric rotation of the eccentric portion 7 b of the crankshaft 7 to the orbiting scroll 6, but functions to make a revolving motion without rotating the orbiting scroll 6.

  The electric motor 4 includes a stator 4a and a rotor 4b. The stator 4a is fastened to the sealed container 2 by press-fitting or welding. The rotor 4b is rotatably arranged in the stator 4a. A crankshaft 7 is fixed to the rotor 4b.

  The crankshaft 7 includes a main shaft 7 a and an eccentric portion 7 b and is supported by a main bearing 9 a and a lower bearing 17 provided on the frame 9. The eccentric portion 7 b is formed integrally with the main shaft 7 a of the crankshaft 7 so as to be eccentric, and is fitted to a orbiting bearing provided on the back surface of the orbiting scroll 6. The crankshaft 7 is driven by the electric motor 4, and the eccentric portion 7b is eccentrically rotated with respect to the main shaft 7a, thereby causing the orbiting scroll 6 to orbit. Further, the crankshaft 7 is provided with an oil supply passage 7c for guiding the lubricating oil 13 to the main bearing 9a, the lower bearing 17 and the slewing bearing, and an oil supply pipe 7d for sucking the lubricating oil 13 to the motor-side shaft end and guiding it to the oil supply passage 7c. It is installed.

  Between the back side of the orbiting scroll 6 and the frame 9, a back pressure chamber 14 is formed which is an intermediate pressure between the pressure of the suction pipe 2 d and the pressure of the discharge pressure chamber 2 f. The orbiting scroll 6 is pressed against the fixed scroll 5 by the pressure of the back pressure chamber 14, so-called back pressure, to reduce the gap at the tip of the lap. Lubricating oil 13 sealed at the bottom of the hermetic container 2 through an oil supply passage 7c formed at the center of the crankshaft 7 due to the pressure difference between the pressure in the back pressure chamber 14 and the pressure in the discharge pressure chamber 2f is applied to the main bearing 9a and the like. Supplied. The back pressure chamber 14 is formed in a path for supplying the lubricating oil 13 in the sealed container 2 to the sliding portion of the compression mechanism portion 3.

  When this compressor is operated, the refrigerant gas is guided from the suction pipe 2d to the compression chamber 11 formed by the orbiting scroll 6 and the fixed scroll 5, and is compressed as it is moved in the center direction of the scroll. The compressed refrigerant gas is discharged from the discharge port 5e provided in the approximate center of the base plate 5d of the fixed scroll 5 to the discharge pressure chamber 2f in the sealed container 2, and flows out from the discharge pipe 2e to the outside. .

Although the refrigeration cycle is shown simply, the scroll compressor 1 (discharge pipe 2e), the condenser 18, the expansion valve 19, the evaporator 20, and the scroll compressor 1 (suction pipe 2d) are connected in order, and the refrigerant circulates. It is configured to The condenser 18 is also called a gas cooler in the supercritical refrigeration cycle. For example, a heat pump water heater is operated as a supercritical refrigeration cycle using CO ₂ or the like as a refrigerant. Since the fluid passing through the condenser or gas cooler is heated, it may be called a heater so as to include both.

  The refrigerant gas flowing out of the compressor is radiated and liquefied by the condenser 18 and decompressed by the expansion valve 19. The decompressed refrigerant absorbs heat and evaporates in the evaporator 20 and is sucked into the suction chamber 10 again from the suction pipe 2d.

  The suction pipe 2d and the back pressure pipe 2g are communicated with each other by a bypass pipe 21, and an electric valve 22 is provided in the bypass pipe 21. The back pressure Pb is controlled by adjusting the opening degree of the electric valve 22. According to this, it is possible to control the back pressure, which is an intermediate pressure between the discharge pressure Pd and the suction pressure Ps, in a direction to lower it to the suction pressure Ps.

  FIG. 2 shows the relationship between the ratio of the back pressure Pb-suction pressure Ps and the compressor efficiency with the pressure ratio as a parameter, and is based on an experiment. Here, the vertical axis and the horizontal axis indicate the ratio with the peak efficiency of 2.25 as the peak efficiency. That is, the Pb-Ps ratio referred to in FIG. 2 is (Pb-Ps) / (Pb0-Ps0), and represents the magnification from Pb0-Ps0 as a reference.

  From this figure, it can be seen that the Pb-Ps ratio has an appropriate value in terms of efficiency. For example, if the pressure ratio is 2.25, the Pb-Ps ratio is about 1.0 (2.25, 1.0), and the others are (2.5, 1.2), (2.75). , 1.35), (3.0, 1.08), (3.33, 1.25), (3.67, 1.39), and so on. These values that give at least the peak compressor efficiency (Pd / Ps, Pb-Ps ratio) are stored as the data group 0 in the control unit 25 for each compression ratio. For example, in the case of a compressor of a heat pump water heater, the change in the pressure ratio is caused by an outside air temperature, a target hot water storage temperature, or the like.

  Here, the back pressure Pb−the suction pressure Ps is a factor for pressing the orbiting scroll 6 against the fixed scroll 5. Conversely, the factor of the force that separates these scrolls is discharge pressure Pd−suction pressure Ps. Therefore, if the information about the discharge pressure Pd and the information about the suction pressure Ps are obtained, the back pressure Pb−the suction pressure Ps, that is, the pressing force can be controlled by obtaining the information about Pb as described later.

  A refrigeration cycle apparatus such as a heat pump water heater is different from a system using a scroll type air compressor in that the suction pressure and the discharge pressure change variously depending on the load state and the operation state. When the opening degree of the motor-operated valve 22 is adjusted so as to achieve an appropriate pressing force in terms of efficiency under such various pressure conditions, energy saving of the compressor can be achieved throughout the year. This is because, if the pressing force is increased, the loss due to refrigerant leakage between the two scrolls can be reduced, but the loss due to sliding friction increases, and conversely the pressing force is reduced. Then, the loss due to the sliding friction can be reduced, but the loss due to the refrigerant leakage between the scrolls becomes large.

  Therefore, it is necessary to control the back pressure Pb−the suction pressure Ps so as to balance these and obtain an appropriate pressing force. The back pressure Pb is directly controlled by the opening degree of the motor-operated valve 22.

  Next, a method for controlling the back pressure Pb-suction pressure Ps ratio will be described. Note that controlling the back pressure Pb-suction pressure Ps ratio is substantially the same as controlling "back pressure Pb-suction pressure Ps".

  A discharge pressure sensor 23 for detecting the discharge pressure Pd is attached to the discharge pipe, and an evaporation temperature sensor 24 for detecting the evaporation temperature Te is attached to the evaporator 20. Since it is the discharge pressure Pd that is controlled by the scroll compressor 1, it is preferable to directly detect and control this. The discharge pressure sensor 23 is mainly used for calculating the discharge pressure Pd, and the evaporation temperature sensor 24 is mainly used for calculating the suction pressure Ps by detecting the evaporation temperature Te.

  The detected discharge pressure Pd and evaporation temperature Te are input to the control unit 25 (C / U), and the control unit 25 determines that the back pressure Pb−the suction pressure Ps is based on the discharge pressure Pd and the suction pressure Ps. The controller 25 calculates the opening degree of the motor-operated valve 22 so as to be appropriate from the viewpoint of efficiency, that is, so that the back pressure Pb is appropriate. That is, the discharge pressure is calculated from the information from the discharge pressure sensor 23, the suction pressure is calculated from the information from the evaporation temperature sensor 24, and the motor-operated valve 22 is calculated using the calculated discharge pressure information and the suction pressure information. Is calculated. The calculated opening is sent from the control unit 25 to the motor-operated valve 22, and the motor-operated valve 22 is driven so as to have a desired opening.

A method for calculating the opening will be described with reference to FIGS. FIG. 3 summarizes the motor valve opening degree of the peak efficiency under each pressure condition shown in FIG. 2 as a pressure ratio, and is based on an experiment. That is, when the refrigeration cycle is operated on this straight line, that is, when the compressor in the refrigeration cycle is operated, the compressor efficiency peaks. As can be seen from FIG. 3, the pressure ratio Pd / Ps and the motor valve opening% can be approximated by a straight line for each suction pressure Ps and are expressed by the following equations.
Opening = slope x pressure ratio + constant

  The constant is the intercept of the approximate line. It can be seen that the larger the pressure ratio (the lower the suction pressure Ps), the larger the opening and the larger the constant. Here, for example, approximate expressions of Ps = 3 MPa, 4 MPa, and 5 MPa are obtained. Although roughly, each corresponds to the suction pressure Ps under winter conditions, intermediate conditions, and summer conditions. This approximate expression is held as a data group 1 in the control unit 25 for each value of Ps. The controller 25 controls the opening of the motor-operated valve based on the above approximate expression, that is, the approximate expression of the motor-operated valve opening for each suction pressure so as to control the back pressure, which is the pressure in the back pressure chamber, to a desired pressure. Is calculated and controlled.

  Then, actually run the compressor. Since the discharge pressure Pd is known from the discharge pressure sensor 23 and the suction pressure Ps is known from the evaporation temperature sensor 24, the abscissa of FIG. 3 can be specified (for example, a broken line of Pd / Ps≈2.85). At this time, the opening degree x1 corresponding to the value of the current suction pressure Ps is obtained by a ratio using the two opening degrees a1 and a2 closest to them.

When the suction pressure Ps is between an approximate expression of Ps = 3 MPa and an approximate expression of Ps = 4 MPa, for example, Ps = 3.5 MPa, first, the opening degrees a1 and a2 on both sides of the opening degree x1 to be obtained are respectively From the approximate expression of When it is obtained, the opening degree x1 to be obtained is obtained by the following equation.
(x1-a2) / (a1-a2) = (Ps-4 MPa) / (3 MPa-4 MPa)
∴x1 = a2 + (Ps-4 MPa) / (3 MPa-4 MPa) × (a1-a2)
→ x1 = a2 + (4MPa-Ps) / (4MPa-3MPa) × (a1-a2)

  The last equation is just adjusted ± to make it intuitively easy to understand.

  As described above, one of the pressure difference between the adjacent first and second approximate expressions (ex. Ps = 3 MPa and 1 MPa when Ps = 4 MPa) and the first and second approximate expressions. Using the differential pressure (ex.4 MPa-Ps) between the suction pressure (ex.Ps = 4 MPa) and the suction pressure calculated from the evaporation temperature (this is the actual suction pressure during compressor operation), the pressure difference , The opening degree (ex.x1) can be calculated from the ratio of the differential pressures. In addition, it says that it calculates | requires by interpolating the case where the opening degree calculated | required in this way exists in the inside of the opening degree known from another method.

Further, when the suction pressure Ps is not between the approximate expressions, for example, between the approximate expression of Ps = 4 MPa and the approximate expression of Ps = 5 MPa, and Ps = 5.5 MPa, first, the opening x4 to be obtained is set to The two closest openings a2 and a3 are obtained from their approximate expressions. When it is obtained, the opening degree x4 to be obtained is obtained by the following equation.
(x4-a3) / (a2-a3) = (Ps-5 MPa) / (4 MPa-5 MPa)
∴x4 = a3 + (Ps-5 MPa) / (4 MPa-5 MPa) × (a2-a3)
→ x4 = a3- (Ps-5 MPa) / (5 MPa-4 MPa) × (a2-a3)

  The last equation is just adjusted ± to make it intuitively easy to understand.

Here, FIG. 3 shows an approximate expression from the relationship between the opening degree% and the pressure ratio Pd / Ps. However, the approximate expression has the same tendency even if the pressure difference Pd−Ps is summarized as shown in FIG. The calculation method of the opening degree can be applied.
Opening angle = inclination x pressure difference + constant

  Although the approximate expression is represented by a simple linear line, it is needless to say that the same control is possible even when approximated by a polynomial that is almost a straight line. Further, although the discharge pressure Pd is detected here, the same effect can be obtained even if the condensation temperature is detected and converted to the discharge pressure. Alternatively, the supercritical refrigeration cycle does not condense and does not necessarily reach the condensing temperature. Therefore, even if the refrigerant inlet temperature is detected by the refrigerant inlet temperature sensor, the same effect can be obtained. By using the temperature sensor as described above, it is possible to construct a system at a lower cost than using the discharge pressure sensor 23 separately. However, if the discharge pressure sensor 23 is already necessary for another purpose, it goes without saying that it is preferable to share it with the purpose. The same applies hereinafter.

  As described above, the pressure difference between the adjacent first and second approximate expressions (ex. Ps = 4 MPa and 1 MPa in the case of Ps = 5 MPa) and the opening desired to be obtained from the first and second approximate expressions Using the differential pressure (ex.5 MPa-Ps) between the suction pressure closer to the pressure (ex.Ps = 5 MPa) and the suction pressure calculated from the evaporation temperature (this is the actual suction pressure during compressor operation) The opening degree (ex.x4) can be calculated from the pressure difference and the ratio of the differential pressures. In addition, it says that it calculates | requires by extrapolating the case where the opening degree calculated | required in this way is outside the opening degree known from another method.

  The processing of the control unit 25 when the approximate straight line shown in FIG. 4 is used will be described with reference to the control flowchart shown in FIG. The discharge pressure Pd and the evaporation temperature Te are detected. The suction pressure Ps is calculated from Te. The difference Pd−Ps is calculated. Which approximate expression is used is determined from Ps. The opening degree x is calculated. The opening x is output to the motor-operated valve 22. In order to control the opening, a stepping motor is used for the motor-operated valve 22.

  If the refrigeration cycle, that is, the compressor is operated at the opening degree x, the compressor efficiency can be peaked. By adopting the above-described configuration, it is possible to achieve a differential pressure that is efficient in various conditions, that is, a ratio of back pressure Pb to suction pressure Ps, and energy saving of the compressor can be achieved throughout the year.

  In this way, in the configuration in which the back pressure chamber and the suction pipe are connected by the bypass pipe and the motor valve is provided in the bypass pipe, information is obtained from the sensor that detects the operating pressure condition, and the back pressure is an appropriate value based on the information. By controlling the motor-operated valve opening so that the opening becomes larger when the suction pressure is low than when it is high, various forces can be obtained without excessively pressing the orbiting scroll 6 against the fixed scroll 5. The operation of the refrigeration cycle appropriate for the compressor efficiency can be performed under the operating conditions. Therefore, a highly efficient refrigeration cycle apparatus can be realized in a wide range of operating conditions.

  Consider applying such a refrigeration cycle apparatus to, for example, a heat pump water heater. FIG. 10 is a unit configuration diagram of the heat pump water heater. Those having the same reference numerals as those described above have the same operational effects, so the description thereof will be omitted.

The heat pump water heater is a supercritical refrigeration cycle using CO ₂ as a refrigerant, and is a refrigeration cycle apparatus including a tank for storing hot water. Hot water is generated using a heater, the hot water is stored in a tank, and the hot water from the tank is used in a kitchen or a bath. Further, in addition to the configuration of the refrigeration cycle apparatus described above, it is possible to operate in consideration of the load state (target hot water storage temperature, outside air temperature, operation state, etc.). For example, the load state detection means includes a remote controller for setting the hot water storage temperature and an outside air temperature sensor, and information such as the target hot water storage temperature and the outside air temperature is input to the control unit (25).

  When the time set at midnight (for example, 3 am) is reached, the scroll compressor 1 is activated, and the compressed high-temperature and high-pressure refrigerant is discharged from the discharge pipe 2e. The discharged refrigerant is heat-exchanged with water in the hot water storage tank 32 by the water-refrigerant heat exchanger 29 and cooled. On the other hand, water in the hot water storage tank 32 is conveyed by the water circulation pump 31, and water in the lower part of the hot water storage tank 32 is heated by the water-refrigerant heat exchanger 29 and stored as hot water in the upper part of the hot water storage tank 32.

  On the other hand, the refrigerant leaving the water-refrigerant heat exchanger 29 is decompressed by the expansion valve 19 and enters the evaporator 20 to absorb the heat of the atmosphere and evaporate. The refrigerant exiting the evaporator 20 is sucked into the scroll compressor 1 from the suction pipe 2d and is compressed again here.

  Next, a control method will be described. The remote controller 30 sets the temperature of hot water stored in the hot water storage tank 32 by the user. Signals from the discharge pressure sensor 23, the evaporation temperature sensor 24, the tapping temperature sensor 28, and the discharge gas temperature sensor 33 are input to the control unit 25 that is a control unit. The hot water temperature sensor 28 is disposed at the inlet of the hot water storage tank 32 downstream of the water-refrigerant heat exchanger 29 in the flow of water.

  When the temperature obtained by the hot water temperature sensor 28 is lower than the hot water temperature set by the remote controller 30, the rotation speed of the scroll compressor 1 is increased to increase the amount of refrigerant circulation, and the discharge gas temperature sensor 33 obtains the temperature. When the temperature is lower than the hot water temperature set by the remote controller 30, the expansion valve 19 is throttled to increase the discharge pressure detected by the discharge pressure sensor 23. With the above method, the hot water temperature of the hot water storage tank 32 is controlled to be a desired temperature, and the operation is stopped at a set time in the early morning (for example, 7:00 am).

  Until the heat pump water heater is started and stopped, the back pressure of the scroll compressor 1 is efficiently converted to an appropriate back pressure by the above control method based on the signals obtained from the discharge pressure sensor 23 and the evaporation temperature sensor 24. The motorized valve 22 can be driven to make a highly efficient refrigeration cycle. That is, the electric input of the scroll compressor 1 is not excessively increased, so that energy saving of the heat pump water heater can be achieved.

  Further, the operation state of the compressor can be taken into consideration. In this case, for example, this can be taken into account by estimating the rotational speed of the compressor from the frequency of the inverter in the control unit.

  For example, when the hot water is stored in the tank at 90 ° C. and when the hot water is stored in the tank at 65 ° C., the back pressure Pb−the suction pressure Ps is greatly different, so that the force with which the orbiting scroll 6 is pressed against the fixed scroll 5 is greatly different. If the pressing force is made appropriate in accordance with the 65 ° C. hot water storage, the pressing force becomes excessive in the 90 ° C. hot water storage. In addition, since it varies depending on the summer and winter seasons, and also varies depending on the driving conditions, there are various areas where the pressing force is excessive.

  Therefore, in addition to the control of the refrigeration cycle apparatus described above, the back pressure Pb is controlled in consideration of the load state, that is, the back pressure Pb is controlled by taking into account the target hot water storage temperature in the tank, or the outside air temperature is taken into account. By controlling Pb or controlling the back pressure Pb in consideration of the operation state, a heat pump water heater with high energy saving performance can be obtained. In addition, the desired back pressure Pb can be achieved earlier. Thus, it is conceivable that the pressing force is made appropriate by taking into account the load state in addition to the information such as the evaporation temperature sensor.

  For example, controlling the back pressure Pb in consideration of the target hot water storage temperature is controlling the back pressure Pb in consideration of the discharge pressure Pd. That is, the back pressure Pb is controlled in accordance with the load state so as to suit the user's desired use state and device use state, and the pressing force is controlled. In addition, controlling the back pressure Pb in consideration of the outside air temperature is to control the back pressure Pb in consideration of the season, a warm region, a cold region, etc., and the suction pressure Ps. That is, the back pressure Pb is controlled in accordance with the load state so as to meet the use conditions of the device, and the pressing force is controlled.

  Further, controlling the back pressure Pb in consideration of the operation state is to control the back pressure Pb in consideration of, for example, the frequency of the inverter from the control unit 25 of the scroll compressor 1. That is, the pressing force is controlled by controlling the back pressure Pb in accordance with the load state so as to suit the operation state of the device such as a pressing force and a loss due to sliding friction (friction loss).

  When the number of revolutions increases, the time required for one revolution of the orbiting scroll 6 is shortened, so that the amount of refrigerant leaking from the compression chamber per revolution is reduced. Accordingly, the amount of refrigerant leaking from the high-pressure compression chamber to the low-pressure compression chamber decreases, so that the high-pressure refrigerant exists closer to the center of the orbiting scroll 6 and the low-pressure refrigerant exists closer to the outside. On the other hand, when the rotational speed is low, the amount of refrigerant leakage described above becomes relatively large, so that a high-pressure refrigerant is present at the outer side to some extent.

  Therefore, the pulling force of both scrolls, that is, the pressing force for pushing down the orbiting scroll 6 is increased. To counter this, it is preferable to increase the push-up force (= pressing force) of the orbiting scroll 6 when the rotational speed is low, that is, to increase the back pressure Pb. In order to increase the back pressure Pb, specifically, the opening of the motor-operated valve is decreased. More specifically, the opening degree of the motor-operated valve when the rotational speed is low is controlled to be smaller than the opening degree of the motor-operated valve when the rotational speed is high.

  Further, when the rotational speed is increased, friction loss at all locations (end plate, tooth tip, tooth side surface, etc.) in contact with both scrolls increases. It is known that this friction loss increases at an order larger than the first order with respect to the rotational speed. Therefore, in a state where the rotational speed is high, it is advantageous for the entire device to lower the back pressure Pb and suppress friction loss. To lower the back pressure Pb, specifically, the opening of the motor-operated valve is increased. More specifically, the opening degree of the motor-operated valve when the rotational speed is high is controlled to be larger than the opening degree of the motor-operated valve when the rotational speed is low.

  The same applies to the following embodiments.

  The second embodiment of the present invention will be described in detail below. FIG. 6 is a longitudinal sectional view of a scroll compressor according to the second embodiment of the present invention, FIG. 7 is a graph showing the relationship between the discharge pressure Pd-suction pressure Ps and the back pressure Pb-suction pressure Ps ratio, and FIG. It is a control flowchart which determines the opening degree of a motor operated valve from the graph of FIG. The same reference numerals as those in the first embodiment have the same functions and effects, and thus the description thereof is omitted.

  6 is provided with a back pressure sensor 26 for detecting the back pressure. The controller 25 receives the discharge pressure Pd, the evaporation temperature Te, and the back pressure Pb, calculates the suction pressure Ps from the evaporation temperature, and uses the discharge pressure Pd and the suction pressure Ps to obtain an appropriate back pressure Pb− in terms of efficiency. The suction pressure Ps (ratio) is calculated. This concept is the same as that in the first embodiment, and is performed based on the data group 0 in the first embodiment.

  The back pressure Pb-suction pressure Ps ratio held in the control unit 25 is compared with the back pressure Pb-suction pressure Ps ratio input to the control unit 25 at this time by the operation of the refrigeration cycle, and electric is performed so that both are equal. The valve 22 is driven. The back pressure Pb input to the controller 25 this time is detected by the back pressure sensor 26, and the suction pressure Ps is calculated from the evaporation temperature Te. The control unit 25 calculates the back pressure, which is the pressure of the back pressure chamber, from the information from the back pressure sensor 26, calculates the suction pressure from the information from the evaporation temperature sensor 24, and calculates the back pressure information and the calculated back pressure information. The open / close control of the motor-operated valve 22 is performed using the information on the suction pressure.

A method of calculating the opening will be described with reference to FIGS. FIG. 7 summarizes the peak efficiency back pressure Pb−suction pressure Ps under each pressure condition shown in FIG. 2 as a pressure difference, and is based on an experiment. As in FIG. 3, as can be seen from FIG. 7, the pressure difference “Pd−Ps” and the pressure difference “Pb−Ps” can be approximated by a straight line for each suction pressure Ps, and are expressed by the following equations.
Pb−Ps = slope × (Pd−Ps) + constant

  Here, it can be seen that the constant is opposite to the approximate expression shown in FIG. 3 and that the pressure difference “Pb−Ps” increases as the suction pressure Ps increases. Here, similar to the first embodiment, approximate expressions of Ps = 3 MPa, 4 MPa, and 5 MPa are obtained. This approximate expression is held as a data group 2 in the control unit 25 for each value of Ps. The control unit 25 calculates the differential pressure corresponding to the suction pressure calculated on the basis of the above approximate expression, that is, the approximate expression of the differential pressure between the back pressure and the suction pressure for each suction pressure. The motor-operated valve 22 is controlled to open and close so that the back pressure calculated based on information from the sensor becomes the calculated back pressure.

  Then, actually run the compressor. Since the discharge pressure Pd is known from the discharge pressure sensor 23 and the suction pressure Ps is known from the evaporation temperature sensor 24, the abscissa of FIG. 7 can be specified (for example, a broken line of Pd−Ps≈6.5). At this time, the differential pressure x10 corresponding to the value of the current suction pressure Ps is obtained by the ratio from the two differential pressures closest to them.

When the suction pressure Ps is between an approximate expression of Ps = 3 MPa and an approximate expression of Ps = 4 MPa, for example, Ps = 3.5 MPa, first, the differential pressures a8 and a9 on both sides of the differential pressure x10 to be obtained are respectively From the approximate expression of When it is obtained, the differential pressure x10 to be obtained is obtained by the following equation.
(x10-a9) / (a8-a9) = (Ps-3 MPa) / (4 MPa-3 MPa)
∴x10 = a9 + (Ps−3 MPa) / (4 MPa−3 MPa) × (a8−a9)
→ x10 = a9 + (Ps−3 MPa) / (4 MPa−3 MPa) × (a8−a9)

  The last equation is just adjusted ± to make it intuitively easy to understand. However, the contents and the expression form are the same as the above formula. The degree of opening is obtained by interpolating in this way, as in the first embodiment.

In addition, when the suction pressure Ps is not between the approximate expressions, for example, between the approximate expression of Ps = 4 MPa and the approximate expression of Ps = 5 MPa, and Ps = 5.5 MPa, first, the differential pressure x11 is obtained. The two closest differential pressures a7 and a8 are obtained from the approximate equations. When it is obtained, the differential pressure x11 to be obtained is obtained by the following equation.
(x11-a7) / (a8-a7) = (Ps-5 MPa) / (4 MPa-5 MPa)
∴x11 = a7 + (Ps−5 MPa) / (4 MPa−5 MPa) × (a8−a7)
→ x11 = a7 + (Ps-5 MPa) / (5 MPa-4 MPa) × (a7-a8)

  The last equation is just adjusted ± to make it intuitively easy to understand. The degree of opening is obtained by extrapolation in this way, as in the first embodiment.

  The processing of the control unit 25 when the approximate straight line shown in FIG. 7 is used will be described with reference to the control flowchart shown in FIG. The discharge pressure Pd and the evaporation temperature Te are detected. The suction pressure Ps is calculated from Te. Then, Pd−Ps is calculated. Which approximate expression is used is determined from Ps. Then, the differential pressure x is calculated. When the differential pressure x is smaller than Pb-Ps, the valve is opened, and when the differential pressure x is larger than Pb-Ps, the valve is closed. This operation is feedback control. In addition, when the discharge pressure Pd of the compressor is changed by changing the desired hot water storage temperature, the operation is first performed by the method of the first embodiment, and then the feedback control by the second embodiment may be performed.

  If the refrigeration cycle, that is, the compressor is operated with this differential pressure x, the compressor efficiency can be peaked. By adopting the above configuration, a differential pressure that is efficient in various conditions, that is, a ratio of back pressure Pb to suction pressure Ps, can be achieved, and energy saving of the device can be achieved throughout the year.

  In this way, in the configuration in which the back pressure chamber and the suction pipe are connected by the bypass pipe and the motor valve is provided in the bypass pipe, information is obtained from the sensor that detects the operating pressure condition, and the back pressure is an appropriate value based on the information. Therefore, when the suction pressure is high, the motor valve opening is controlled so that the differential pressure between the back pressure and the suction pressure is greater than when the suction pressure is low. Cycle operation can be performed. Therefore, a highly efficient refrigeration cycle apparatus can be realized in a wide range of operating conditions.

  In the first embodiment, the differential pressure is controlled by controlling the opening, but in the second embodiment, the differential pressure is directly controlled. In this configuration, the back pressure is detected and the motor-operated valve 22 is opened / closed in comparison with an appropriate differential pressure, that is, back pressure Pb−suction pressure Ps (ratio). Therefore, due to secular change, accumulation of dust, clogging, etc. Even if the flow passage cross-sectional area of the motor-operated valve 22 changes from the beginning, it can be controlled to an appropriate differential pressure, that is, a back pressure Pb-suction pressure Ps ratio. Moreover, since the back pressure Pb itself is detected and controlled, the pressing force can be controlled with high accuracy.

  A third embodiment of the present invention will be described with reference to FIG. In this embodiment, the back pressure control valve shown in FIG. 9 is provided in the scroll compressor shown in FIGS. The back pressure control valve 16 will be described. A spring accommodating hole 5 f is formed in the fixed scroll 5. A through hole 5g is formed on the back pressure chamber 14 side of the spring housing hole 5f, and a piece 16a is press-fitted into the through hole 5g. The piece 16a is formed with a communication hole 16b that allows the spring housing hole 5f and the back pressure chamber 14 to communicate with each other.

  A valve body 16c is pressed against the spring housing hole 5f by a spring 16d so as to close the communication hole 16b. The spring 16d is attached to a seal member 16e, and the seal member 16e is press-fitted into the fixed scroll 5 so as to partition the spring housing hole 5f and the discharge pressure chamber 2f. On the side surface of the spring housing hole 5f, there is formed a conduction path 5i that communicates with the R groove 5h formed in the end surface portion of the fixed scroll 5. The R groove 5 h communicates with the suction chamber 10.

  Next, the operation will be described. Lubricating oil 13 stored in the lower part of the sealed container 2 is supplied to each bearing portion through the oil supply pipe 7d and the oil supply passage 7c due to a pressure difference between the sealed container 2 and the back pressure chamber 14. The lubricating oil 13 supplied to the bearing portion enters the back pressure chamber 14 where the refrigerant dissolved in the lubricating oil 13 foams and raises the pressure in the back pressure chamber 14. When the pressure difference between the back pressure chamber 14 and the spring housing hole 5f becomes larger than the urging force of the spring 16d, the valve body 16c opens, and the lubricating oil 13 in the back pressure chamber 14 passes through the conduction path 5i and the R groove 5h, and the suction chamber 10 To be supplied. That is, the pressure in the back pressure chamber 14 is the suction pressure + a constant value (this constant value is determined by the spring force).

  In the case where the motor-operated valve 22 stops in a fully closed state due to a failure or the like, there is no passage for extracting gas from the back pressure chamber 14, so the pressure of the back pressure Pb becomes the discharge pressure Pd. It can also be imagined that when the pressure in the back pressure chamber 14 becomes the discharge pressure Pd, the bearing cannot be lubricated and a galling phenomenon occurs. However, by providing the back pressure control valve 16 and setting the spring force to the highest back pressure Pb−suction pressure Ps in the operating range, the compressor can be operated even if the electric valve 22 fails. You can continue. That is, by operating the back pressure control valve 16, the back pressure Pb is set to an intermediate pressure between the discharge pressure Pd and the suction pressure Ps, so that oil can be reliably supplied and a galling phenomenon can be avoided.

DESCRIPTION OF SYMBOLS 1 Scroll compressor 2 Sealed container 2a Case 2b Cover chamber 2c Bottom chamber 2d Suction pipe 2e Discharge pipe 2f Discharge pressure chamber 2g Back pressure pipe 3 Compression mechanism part 4 Electric motor 4a Stator 4b Rotor 5 Fixed scroll 5c, 6a Wrap 5d, 6b Base plate 5e Discharge port 5f Spring storage hole 5g Through hole 5h R groove 5i Conducting path 6 Orbiting scroll 7 Crankshaft 7a Main shaft 7b Eccentric part 7c Oil supply passage 7d Oil supply pipe 8 Bolt 9 Frame 9a Main bearing 10 Suction chamber 11 Compression chamber 12 Oldham ring 13 Lubricating oil 14 Back pressure chamber 15 Release valve device 16 Back pressure control valve 16a Piece 16b Communication hole 16c Valve body 16d Spring 16e Seal member 17 Lower bearing 18 Condenser 19 Expansion valve 20 Evaporator 21 Bypass pipe 22 Motor operated valve 23 Discharge pressure sensor 24 Evaporation temperature sensor 25 Control unit

Claims (16)

A refrigeration cycle apparatus in which a suction section of a compressor in which a suction chamber and a back pressure chamber are communicated by a bypass pipe, a heater, an expansion valve, an evaporator, and a suction section of the compressor are sequentially connected,
A motor-operated valve arranged in the bypass pipe for controlling the pressure of the back pressure chamber and adjusting the flow of the refrigerant;
An evaporation temperature sensor for detecting an evaporation temperature in the evaporator;
A sensor for detecting information capable of obtaining a discharge pressure from the compressor;
Based on information from the evaporation temperature sensor and the sensor, a control unit that controls the opening of the motor-operated valve;
A refrigeration cycle apparatus comprising: In claim 1,
The refrigeration cycle apparatus, wherein the sensor is a pressure sensor that detects a discharge pressure of the compressor. In claim 1,
The refrigeration cycle apparatus, wherein the sensor is a condensing temperature sensor that detects a condensing temperature in the heater. In claim 1,
The controller is
When the discharge pressure is calculated from the information from the sensor, the suction pressure is calculated from the information from the evaporation temperature sensor, and the suction pressure is low using the calculated discharge pressure information and the suction pressure information. A refrigeration cycle apparatus, wherein the opening degree of the motor-operated valve is calculated so that the opening degree is larger than when it is high, and the opening degree of the motor-operated valve is controlled. In claim 4,
The controller is
The opening degree of the motor-operated valve is calculated based on an approximate expression of the opening degree of the motor-operated valve for each arbitrary suction pressure so as to control the back pressure, which is the pressure of the back-pressure chamber, to a desired pressure. A refrigerating cycle device that controls the opening degree of the refrigeration. In claim 1,
A refrigeration cycle apparatus comprising a back pressure sensor for detecting the pressure in the back pressure chamber. In claim 6,
The controller is
Back pressure that is the pressure of the back pressure chamber is calculated from information from the back pressure sensor, suction pressure is calculated from information from the evaporation temperature sensor, and the calculated back pressure information and suction pressure information are calculated. Is used to control the opening and closing of the motor-operated valve so that the differential pressure between the back pressure and the suction pressure is greater when the suction pressure is high than when the suction pressure is low. In claim 7,
The controller is
A back pressure corresponding to the calculated suction pressure is calculated based on an approximate expression of a back pressure for each suction pressure, and the back pressure calculated based on information from the back pressure sensor is calculated as the calculated back pressure. The refrigeration cycle apparatus characterized by controlling the said motor operated valve. In claim 1,
A refrigeration cycle apparatus comprising a back pressure control valve between the back pressure chamber and the suction chamber. A compressor discharge unit that connects a suction chamber and a back pressure chamber with a bypass pipe, a heater, an expansion valve, an evaporator, and a tank for storing hot water are sequentially connected to the compressor suction unit. Heat pump water heater,
A motor-operated valve arranged in the bypass pipe for controlling the pressure of the back pressure chamber and adjusting the flow of the refrigerant;
An evaporation temperature sensor for detecting an evaporation temperature in the evaporator;
A sensor for detecting information capable of obtaining a discharge pressure from the compressor;
Based on information from the evaporating temperature sensor, the sensor, and the load state detecting means, a controller that controls the opening of the motor-operated valve;
Heat pump water heater equipped with. In claim 10,
A heat pump water heater comprising load state detection means for detecting a load state of the heat pump water heater. In claim 11,
The load state detection means is an outside air temperature sensor that detects the temperature of outside air,
The heat pump water heater, wherein the load state is an outside air temperature. In claim 11,
The load state detecting means is a remote control,
The said control part sets the target hot water storage temperature to the said tank input from the said remote control, and controls the opening degree of the said motor operated valve based on the target hot water storage temperature to the said tank, The heat pump water heater characterized by the above-mentioned. In claim 10,
The said control part detects the driving | running state of the said heat pump water heater, and controls the opening degree of the said motor operated valve based on the said detected driving | running state, The heat pump water heater characterized by the above-mentioned. In claim 14,
The operating state is the rotation speed of the compressor, and the opening degree of the motor-operated valve when the rotation speed is low is controlled smaller than the opening degree of the motor-operated valve when the rotation speed is high. Water heater. In claim 14,
The operation state is the rotation speed of the compressor, and the opening degree of the motor-operated valve when the rotation speed is high is controlled to be larger than the opening degree of the motor-operated valve when the rotation speed is low. Water heater.

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