JP2012002426A - Heat pump cycle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To protect a compressor in defrost operation in a heat pump cycle in which the defrost operation of an evaporator is performed by increasing a throttle opening of a variable throttle mechanism.SOLUTION: The throttle opening of an electric type expansion valve 16 is made full until at least one condition is satisfied out of that after an operation request signal of a heart pump signal 13 is outputted, a rise rate ΔTd of a discharge-side refrigerant temperature Td reaches a rising rate ΔKTd of a reference discharge side or lower, or a rise rate ΔTwi of an inflow water temperature Twi reaches a rising rate ΔKTwi of a reference in-draft side or lower. Thereby, even if the discharge side refrigerant temperature Td of the compressor 14 or the inflow water temperature Twi flowing in to a water/refrigerant heat exchanger 15 is raised abruptly, an abrupt rising of the high pressure side refrigerant pressure Ph of a cycle is suppressed, then, cycle constitution equipment can be protected.

Description

  The present invention relates to a heat pump cycle that heats a fluid to be heated by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the compressor and the fluid to be heated.

  2. Description of the Related Art Conventionally, a heat pump cycle that heats a fluid to be heated by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the compressor and the fluid to be heated is known. For example, Patent Literature 1 discloses a heat pump cycle applied to a heat pump hot water heater that heats hot water as a fluid to be heated.

  More specifically, the heat pump water heater of Patent Document 1 has a hot water storage tank for storing hot water, and the hot water heated by the water-refrigerant heat exchanger of the heat pump cycle is disposed above the hot water storage tank. The hot water supply water of the temperature lower than the upper side stored by the lower side of a hot water storage tank is made to flow in into a water-refrigerant heat exchanger.

  Furthermore, in this heat pump cycle, before starting the compressor at the time of start-up, various types of detecting the incoming water temperature of the hot water flowing into the water-refrigerant heat exchanger, the discharge side refrigerant temperature on the compressor discharge side, the outside air temperature, etc. Based on the detection value of the temperature sensor, the target opening degree of the variable throttle mechanism for decompressing and expanding the refrigerant flowing out of the water-refrigerant heat exchanger is determined.

  Then, after changing the actual opening of the variable throttle mechanism to the target opening, the compressor is operated, and then the refrigerant discharge capacity of the compressor reaches a predetermined capacity, and then the water-refrigerant heat exchanger By changing the opening degree of the variable throttle mechanism so that the temperature of the hot water heated at the temperature approaches the desired temperature, an attempt is made to suppress the rapid increase in the refrigerant pressure on the high-pressure side of the cycle immediately after startup. Yes.

JP 2007-155157 A

  However, according to the study of the present inventor, when the heat pump cycle of Patent Document 1 is actually operated, the rapid increase in the high-pressure side refrigerant pressure Ph immediately after startup may not be sufficiently suppressed. Then, when this inventor investigated the cause, the actual water intake temperature Twi and the discharge side refrigerant | coolant temperature Td may change rapidly immediately after starting of a heat pump cycle, and this rapid temperature change is high pressure. It was found that the side refrigerant pressure Ph was rapidly increased.

  For example, when the heat pump cycle is restarted in a short time after the operation of the heat pump cycle (specifically, the compressor) is stopped, as shown in FIG. 4A, the discharge-side refrigerant temperature Td on the compressor discharge side is The value detected at the time of starting the heat pump cycle may increase rapidly immediately after the operation of the compressor. FIG. 4A is a time chart showing changes in the discharge-side refrigerant temperature Td and the like on the compressor discharge side at the start of the heat pump cycle.

  The reason why such a sudden increase in the discharge-side refrigerant temperature Td occurs is that when the heat pump cycle is restarted in a short time after the operation of the heat pump cycle is stopped, the temperature of the compressor having a large heat capacity is not sufficiently cooled. This is because immediately after the operation of the compressor, the high-temperature refrigerant heated by the amount of heat of the compressor itself is discharged.

  Furthermore, when the discharge-side refrigerant temperature Td rises, the high-pressure side refrigerant pressure Ph also rises. Therefore, at the opening of the variable throttle mechanism determined at the start of the heat pump cycle, the high-pressure side refrigerant pressure of the cycle The rapid increase in Ph cannot be sufficiently suppressed. As a result, there is a problem that the high pressure side refrigerant pressure Ph exceeds the pressure resistance of the cycle component device and the cycle component device cannot be protected.

  For example, when the heat pump cycle is restarted after a long time has elapsed after the heat pump cycle is stopped, as shown in FIG. 4B, the incoming water temperature Twi may rapidly increase immediately after startup. FIG. 4B is a time chart showing changes in the incoming water temperature Twi and the like at the start of the heat pump cycle.

  The reason why such a rapid increase in the incoming water temperature Twi occurs is that the incoming water temperature Twi detected when the heat pump cycle is restarted stays in the hot water supply pipe from the hot water storage tank to the water-refrigerant heat exchanger. This is because of the temperature of the hot water supply.

  In other words, the hot water supply pipe from the hot water storage tank to the water-refrigerant heat exchanger has low heat insulation performance with respect to the hot water storage tank, so the temperature of the hot water staying in the hot water supply pipe is reduced to about the outside temperature. Have Therefore, after the heat pump cycle is restarted, when the hot water that has been kept warm in the hot water storage tank having high heat insulation performance reaches the water-refrigerant heat exchanger, the incoming water temperature Twi is rapidly increased.

  Furthermore, when such a rise in the incoming water temperature Twi occurs, the amount of heat that can be dissipated by the compressor discharge refrigerant to the hot water in the water-refrigerant heat exchanger decreases, so the variable throttle determined at the start of the heat pump cycle With the opening of the mechanism, the rapid increase in the discharge side refrigerant temperature Td and the high pressure side refrigerant pressure Ph cannot be sufficiently suppressed.

  As a result, there is a problem in that it becomes impossible to protect the cycle constituent equipment as in the case where the heat pump cycle is restarted in a short time after the operation of the heat pump cycle is stopped.

  In view of the above points, an object of the present invention is to protect cycle-constituting equipment at the start of a heat pump cycle.

In order to achieve the above object, according to the first aspect of the present invention, the compressor (14) that compresses and discharges the refrigerant, and the high-temperature and high-pressure refrigerant discharged from the compressor (14) and the fluid to be heated are subjected to heat exchange. A heating heat exchanger (15) for heating the fluid to be heated, and a variable throttle mechanism configured to be able to change the throttle opening for decompressing and expanding the high-pressure refrigerant flowing out of the heating heat exchanger (15) ( 16), an evaporator (17) for evaporating the refrigerant decompressed by the variable throttle mechanism (16), a discharge capacity control means (21a) for controlling the refrigerant discharge capacity of the compressor (14), and a variable throttle mechanism Variable throttle control means (21b) for controlling the operation of (16), discharge side temperature detection means (22) for detecting the discharge side refrigerant temperature (Td) on the discharge side of the compressor (14), and discharge capacity control means ( 21a), the operation of the compressor (14) Request signal output means (31) for outputting an operation request signal, and target temperature setting means (32) for setting a target heating temperature (Tset) of the heating target fluid flowing out from the heat exchanger for heating (15). ,
The variable throttle control means (21b) has a variable throttle mechanism before the discharge capacity control means (21a) starts the operation of the compressor (14) when the operation request signal is output from the request signal output means (31). After the throttle opening of (16) is fully open and the compressor (14) is started to operate, the degree of increase in the discharge side refrigerant temperature (Td) detected by the discharge side temperature detection means (22) ( Variable so that the temperature of the fluid to be heated flowing out of the heat exchanger for heating (15) approaches the target heating temperature (Tset) when ΔTd) becomes equal to or less than a predetermined reference discharge side temperature rise degree (ΔKTd). It is characterized by a heat pump cycle that changes the throttle opening of the throttle mechanism (16).

  According to this, when the operation request signal is output from the request signal output means (31), before the discharge capacity control means (21a) starts the operation of the compressor (14), the variable throttle control means (21b). ) Fully opens the throttle opening of the variable throttle mechanism (16), it is possible to reliably avoid a sudden increase in the high-pressure side refrigerant pressure Ph of the cycle when the compressor (14) is operated.

  Further, the variable throttle control means (21b) opens the throttle of the variable throttle mechanism (16) until the increase degree (ΔTd) of the discharge side refrigerant temperature (Td) becomes equal to or less than a predetermined reference discharge side temperature increase degree (ΔKTd). Therefore, it is possible to avoid a sudden increase in the high-pressure side refrigerant pressure Ph of the cycle due to a sudden rise in the discharge-side refrigerant temperature (Td).

  Therefore, it is possible to protect the cycle constituent equipment at the time of starting the heat pump cycle.

  The term “fully open” in this claim does not only mean that the throttle opening is fully opened. Even if the discharge-side refrigerant temperature (Td) rises rapidly, the high-pressure side refrigerant pressure Ph of the cycle. This means that the throttle opening is sufficiently large to prevent the sudden increase of the throttle. As the “degree of increase (ΔTd) in the discharge-side refrigerant temperature (Td)”, an increase amount per unit time of the discharge-side refrigerant temperature (Td) can be employed.

Furthermore, in the invention according to claim 2, in the heat pump cycle according to claim 1, the inflow side temperature detecting means for detecting the inflow side temperature (Twi) of the heating target fluid flowing into the heating heat exchanger (15). (25)
The variable throttle control means (21b) is configured so that the increase degree (ΔTwi) of the inflow side temperature (Twi) detected by the inflow side temperature detection means (25) is after the operation of the compressor (14) is started. When the temperature of the fluid to be heated flowing out from the heat exchanger for heating (15) approaches the target heating temperature (Tset) when the temperature becomes equal to or less than the predetermined reference inflow side temperature rise degree (ΔKTwi), the variable throttle mechanism (16 ) Is changed.

  According to this, the variable throttle control means (21b) opens the throttle of the variable throttle mechanism (16) until the increase degree of the inflow side temperature (Twi) is equal to or less than a predetermined reference inflow side temperature increase degree (ΔKTwi). Therefore, it is possible to avoid a sudden increase in the high-pressure side refrigerant pressure Ph of the cycle due to a sudden rise in the inflow side temperature (Twi).

  Therefore, it is possible to more reliably protect the cycle component equipment at the time of starting the heat pump cycle.

In the invention according to claim 3, the compressor (14) that compresses and discharges the refrigerant, and the high-temperature and high-pressure refrigerant discharged from the compressor (14) and the heating target fluid are subjected to heat exchange, thereby heating A heating heat exchanger (15) for heating the fluid, a variable throttle mechanism (16) configured to change a throttle opening for decompressing and expanding the high-pressure refrigerant flowing out of the heating heat exchanger (15), and a variable Operation of the evaporator (17) for evaporating the refrigerant decompressed by the throttle mechanism (16), the discharge capacity control means (21a) for controlling the refrigerant discharge capacity of the compressor (14), and the variable throttle mechanism (16) Variable throttle control means (21b) for controlling the inflow side, inflow side temperature detection means (25) for detecting the inflow side temperature of the fluid to be heated flowing into the heat exchanger (15) for heating, and discharge capacity control means (21a) The operation of the compressor (14) With the request signal output means for outputting a request signal (31), the target temperature setting means for setting a target heating temperature (Tset) to be heated fluid flowing from the heating heat exchanger (15) and (32),
The variable throttle control means (21b) has a variable throttle mechanism before the discharge capacity control means (21a) starts the operation of the compressor (14) when the operation request signal is output from the request signal output means (31). The degree of increase in the inflow side temperature (Twi) detected by the inflow side temperature detection means (25) after the throttle opening of (16) is fully opened and the compressor (14) is started to operate is as follows: When the temperature of the heating target fluid flowing out from the heating heat exchanger (15) approaches the target heating temperature (Tset) when the temperature becomes equal to or less than a predetermined reference inflow side temperature rise (ΔKTwi), a variable throttle mechanism ( The heat pump cycle which changes the throttle opening degree of 16) is characterized.

  According to this, similarly to the first aspect of the invention, when the compressor (14) is operated, it is possible to reliably avoid the rapid increase in the high-pressure side refrigerant pressure Ph of the cycle. Further, the variable throttle control means (21b) fully opens the throttle opening of the variable throttle mechanism (16) until the increase degree of the inflow side temperature (Twi) becomes equal to or less than a predetermined reference inflow side temperature increase degree (ΔKTwi). Therefore, the high-pressure refrigerant pressure Ph in the cycle can be prevented from rapidly increasing, as in the second aspect of the invention.

  Therefore, it is possible to protect the cycle constituent equipment at the time of starting the heat pump cycle. As the “degree of increase of the inflow side temperature (Twi)”, an increase amount per unit time of the inflow side temperature (Twi) can be adopted.

  According to a fourth aspect of the present invention, in the heat pump cycle according to any one of the first to third aspects, the variable throttle control means (21b) outputs an operation request signal from the request signal output means (31). Thereafter, when a predetermined reference time elapses, the throttle opening of the variable throttle mechanism (16) is adjusted so that the temperature of the heating target fluid flowing out from the heating heat exchanger (15) approaches the target heating temperature (Tset). It is characterized by changing.

  According to this, it is possible to bring the temperature of the fluid to be heated closer to the target heating temperature (Tset) that is a user's desired temperature after the elapse of the reference time after the operation request signal is output from the request signal output means (31). it can.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim is an example which shows a corresponding relationship with the specific means as described in embodiment mentioned later.

1 is an overall configuration diagram of a heat pump type water heater according to an embodiment. It is a flowchart which shows the control processing of the heat pump type water heater of one Embodiment. (A) is a time chart showing changes in the discharge-side refrigerant temperature Td and the like when restarted in a short time after the heat pump cycle of one embodiment is stopped, and (b) It is a time chart which shows changes, such as incoming water temperature Twi at the time of starting. (A) is a time chart showing changes in the discharge-side refrigerant temperature Td and the like when restarted in a short time after the operation of the heat pump cycle of the prior art is stopped, and (b) is restarted after a long time has elapsed. It is a time chart which shows changes, such as incoming water temperature Twi at the time of making it.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, the heat pump cycle 13 of the present invention is applied to the heat pump type hot water heater 10, and FIG. 1 is an overall configuration diagram of the heat pump type hot water heater 10 of this embodiment.

  The heat pump water heater 10 includes a water circulation circuit 12 that circulates hot water in the hot water storage tank 11 and a heat pump cycle 13 that is a heat pump cycle for heating hot water as a fluid to be heated. First, in the water circulation circuit 12, the hot water storage tank 11 for storing hot water is formed of a metal (for example, stainless steel) having excellent corrosion resistance, has a heat insulating structure, and can maintain hot hot water for a long time. It is a tank.

  Hot water stored in the hot water storage tank 11 is discharged from a hot water outlet provided in the upper part of the hot water storage tank 11, mixed with cold water from a water tap at a temperature control valve (not shown), and then adjusted in temperature, to a kitchen, a bath, etc. Hot water is supplied. Further, tap water is supplied from a water supply port provided in the lower part of the hot water storage tank 11.

  The water circulation circuit 12 is provided with an electric water pump 12a as water pressure feeding means for circulating hot water. The operation of the electric water pump 12 a is controlled by a control signal output from the hot water tank side control device 20. Further, among the constituent devices of the water circulation circuit 12, the hot water storage tank 11, the electric water pump 12a and the like are housed in one housing and integrally configured as a tank unit 200, as shown by a thin broken line in FIG. It is arranged outdoors.

  And when the hot water storage tank side control device 20 operates the electric water pump 12a, the hot water is supplied from the hot water outlet 11a provided on the lower side of the hot water tank 11 → the electric water pump 12a → the water-refrigerant heat exchanger described later. It circulates in the order of 15 water passages 15 a → hot water supply water inlet 11 b on the upper side of the hot water storage tank 11.

  The heat pump cycle 13 is a refrigeration cycle in which a compressor 14, a water-refrigerant heat exchanger 15, an electric expansion valve 16, an evaporator 17 and the like are sequentially connected by piping. This heat pump cycle 13 employs carbon dioxide as a refrigerant, and constitutes a supercritical refrigeration cycle in which the pressure of the high-pressure refrigerant discharged from the compressor 14 is equal to or higher than the critical pressure of the refrigerant.

  Further, oil for lubricating the compressor 14 is mixed in the refrigerant, and a part of this oil is dissolved in the liquid phase refrigerant and circulates in the cycle together with the refrigerant. The remaining oil is separated from the refrigerant discharged from the compressor 14 by an oil separator (oil separator) (not shown) and supplied to the compressor 14 suction side.

  The compressor 14 sucks the refrigerant in the heat pump cycle 13 and compresses and discharges the refrigerant until it reaches a critical pressure or higher. More specifically, in the present embodiment, as the compressor 14, a fixed displacement compression mechanism 14a and an electric motor 14b are accommodated in one housing 14c, and the fixed displacement compression mechanism 14a is driven by the electric motor 14b. An electric compressor is used.

  As the fixed capacity compression mechanism 14a, various compression mechanisms such as a scroll compression mechanism and a vane compression mechanism can be employed. The electric motor 14b has a rotational speed controlled by a control signal output from the heat pump side control device 21, and may employ either an AC motor or a DC motor. And the refrigerant | coolant discharge capability of the compressor 14 is changed by this rotation speed control.

  Therefore, the electric motor constitutes the discharge capacity changing means of the compressor 14. Further, the compressor 14 of the present embodiment is configured as a so-called high pressure dome type compressor in which the inside of the housing 14c becomes a high pressure refrigerant atmosphere and the electric motor 14b accommodated in the housing 14c is cooled by the high pressure refrigerant. Yes.

  The refrigerant discharge port of the compressor 14 is connected to the refrigerant passage 15 b inlet side of the water-refrigerant heat exchanger 15. The water-refrigerant heat exchanger 15 is a heat exchanger configured to include a water passage 15a through which hot water passes and a refrigerant passage 15b through which high-temperature and high-pressure refrigerant discharged from the compressor 14 passes. This is a heating heat exchanger that heats hot water by dissipating the amount of heat of the high-temperature and high-pressure refrigerant discharged from the machine 14 to the hot water.

  Note that, in the heat pump cycle 13 of the present embodiment, as described above, a supercritical refrigeration cycle is configured, so that the refrigerant passing through the refrigerant passage 15b of the water-refrigerant heat exchanger 15 is in a supercritical state without condensing. Dissipate heat.

  The inlet side of the electric expansion valve 16 is connected to the outlet side of the refrigerant passage 15 b of the water-refrigerant heat exchanger 15. The electric expansion valve 16 is a variable throttle mechanism that decompresses and expands the high-pressure refrigerant flowing out from the refrigerant passage 15 b of the water-refrigerant heat exchanger 15. Further, the electric expansion valve 16 also functions as a pressure control means for controlling the high-pressure side refrigerant pressure Ph in the cycle from the compressor 14 discharge port side to the electric expansion valve 16 inlet side.

  More specifically, the electric expansion valve 16 includes a valve body 16a configured to be able to change the throttle opening, and an electric actuator 16b including a stepping motor that changes the throttle opening of the valve body 16a. This is a variable aperture mechanism configured as described above. Furthermore, the operation of the electric actuator 16b is controlled by a control signal output from the heat pump side control device 21. Further, the electric expansion valve 16 of the present embodiment hardly exhibits the refrigerant decompression action when the throttle opening of the valve body is fully opened.

  An evaporator 17 is connected to the outlet side of the electric expansion valve 16. The evaporator 17 performs heat exchange between the low-pressure refrigerant decompressed by the electric expansion valve 16 and the outside air (outdoor air) blown by the blower fan 17a, thereby evaporating the low-pressure refrigerant and exerting an endothermic effect. It is a heat exchanger for use. The blower fan 17 a is an electric blower in which the rotation speed (the amount of blown air) is controlled by a control voltage output from the heat pump-side control device 21.

  In this embodiment, a heat exchanger having a well-known fin and tube structure is employed as the evaporator 17. Further, the refrigerant suction port of the compressor 14 is connected to the outlet side of the evaporator 17. Further, each of the constituent devices 14 to 17 of the heat pump cycle 13 described above is housed in one housing and integrally configured as a heat pump unit 300 as shown by a one-dot chain line in FIG. To be arranged outdoors.

  Next, an outline of the electric control unit of the present embodiment will be described. The hot water storage tank side control device 20 and the heat pump side control device 21 are each composed of a well-known microcomputer including a CPU, a ROM, a RAM, and the like and its peripheral circuits.

  The electric water pump 12a and the like described above are connected to the output side of the hot water tank side control device 20, and the electric motor 14b of the compressor 14 and the electric actuator of the electric expansion valve 16 are connected to the output side of the heat pump side control device 21. 16b, the blower fan 17a, etc. are connected. Furthermore, the hot water tank side control device 20 and the heat pump side control device 21 each control the operation of the connected devices.

  The heat pump side control device 21 is configured integrally with control means for controlling the electric motor 14b of the compressor 14, the electric actuator 16b of the electric expansion valve 16, and the like, and controls the operation of these actuators. In the present embodiment, the configuration (hardware and software) for controlling the operation (refrigerant discharge capability) of the electric motor 14b in the heat pump side control device 21 is the discharge capability control means 21a, and the electric actuator of the electric expansion valve 16 is used. The configuration for controlling the operation (throttle opening) of 16b is referred to as variable throttle control means 21b.

  Of course, the discharge capacity control means 21 a and the variable throttle control means 21 b may be configured as separate control devices with respect to the heat pump side control device 21.

  On the other hand, a plurality of tank water temperature sensors (not shown) arranged in the hot water storage tank 11 in the vertical direction are connected to the input side of the hot water tank side control device 20, and detection signals of these sensors are detected. Is input to the hot water storage tank side controller 20. Therefore, the hot water storage tank side controller 20 can detect the temperature and temperature distribution of the hot water supply according to the water level in the hot water storage tank 11 based on the output signal of the water temperature sensor in the tank.

  Further, on the input side of the heat pump side control device 21, a discharge side temperature sensor 22 as discharge side temperature detecting means for detecting a discharge side refrigerant temperature Td on the discharge side of the compressor 14, and a low pressure side refrigerant temperature (refrigerant in the evaporator 17). An evaporator temperature sensor 23 serving as an evaporator temperature detecting means for detecting evaporation temperature) Te, an outside air temperature sensor 24 serving as an outside air temperature detecting means for detecting the outside air temperature Tam for heat exchange with the low-pressure refrigerant in the evaporator 17 and the like. Is connected.

  Note that the evaporator temperature sensor 23 of the present embodiment specifically detects the heat exchange fin temperature of the evaporator 17. Of course, as the evaporator temperature sensor 23, a temperature detecting means for detecting the temperature of other parts of the evaporator 17 may be adopted, or a temperature detecting means for detecting the temperature of the outside air blown from the evaporator 17 may be adopted. May be.

  Furthermore, the input side of the heat pump side control device 21 has an incoming water temperature sensor 25 as an inflow side temperature detecting means for detecting an incoming water temperature Twi which is a hot water temperature at the inlet side of the water passage 15a of the water-refrigerant heat exchanger 15. A boiling temperature sensor 26 or the like is connected as a boiling temperature detecting means for detecting a boiling temperature Two that is the temperature of the hot water supply water at the outlet of the water passage 15a of the water-refrigerant heat exchanger 15, and detection signals of these sensors are detected. Is input to the heat pump side control device 21.

  Further, an operation panel 30 is connected to the input side of the heat pump side control device 21. The operation panel 30 includes an operation / stop switch 31 as a request signal output means for outputting an operation request signal or a stop request signal of the heat pump type hot water heater 10 (specifically, the compressor 14 of the heat pump cycle 13), hot water supply A hot water supply temperature switch 32 or the like is provided as target temperature setting means for setting the hot water supply temperature (target heating temperature) Tset of water.

  Moreover, the hot water storage tank side control device 20 and the heat pump side control device 21 are electrically connected to each other and configured to be able to communicate with each other. Thereby, based on the detection signal and operation signal which were input into one control apparatus, the other control apparatus can also control operation | movement of the above-mentioned various actuators 12a, 14b, 16b, 17a. Therefore, the hot water tank side control device 20 and the heat pump side control device 21 may be integrally configured as one control device.

  Next, the operation of the heat pump type water heater 10 of the present embodiment having the above configuration will be described with reference to FIGS. First, FIG. 2 is a flowchart showing a control process executed by the heat pump side control device 21. This control process starts when the operation / stop switch 31 is turned on (ON) and an operation request signal is output in a state where power is supplied to the heat pump hot water heater 10 from the outside.

  First, in step S1, initialization processing such as flags and timers is performed. In this initialization process, the activation flag SSfg indicating whether or not the heat pump type hot water heater 10 has just been activated is set to 1. In the next step S2, the detection signals detected by the sensor groups 22 to 26 and the operation signals output from the operation panel 30 are read, and the process proceeds to step S3.

  In step S <b> 3, it is determined whether or not the heat pump type water heater 10 has just been started. Specifically, if the activation flag SSfg = 1, it is determined that the activation has just been started, and the process proceeds to step S5. On the other hand, if the activation flag SSfg = 1 is not set, it is determined that it is not during immediately after activation but during normal operation in which hot water is heated to a user's desired temperature, and the process proceeds to step S4.

  In step S4, the control states of various actuators during normal operation are determined based on the detection signal and operation signal read in step S2. For example, for the control signal output to the electric water pump 12a, the boiling temperature Two is determined so as to approach the set hot water supply temperature set by the operation panel 30.

  Further, the control signal output to the electric actuator 16b of the electric expansion valve 16 is determined so that the high-pressure side refrigerant pressure Ph of the cycle becomes the target high-pressure during normal operation. The target high pressure during normal operation is determined based on the temperature of the high pressure refrigerant flowing out of the water-refrigerant heat exchanger 15 with reference to a control map stored in the heat pump side control device 21 in advance. The coefficient (COP) is determined to be substantially the maximum. Note that the temperature of the high-pressure refrigerant flowing out of the water-refrigerant heat exchanger 15 can be estimated from the boiling temperature Two.

  Further, the control signal output to the electric motor 14b of the compressor 14 is determined so that the low-pressure side refrigerant temperature Te approaches the target low-pressure temperature. This target low-pressure temperature is based on the incoming water temperature Twi detected by the incoming water temperature sensor 25, the boiling temperature Two detected by the boiling temperature sensor 26, the outside air temperature Tam, the target heating temperature Tset set by the operation panel 30, and the like. Determined.

  On the other hand, if the activation flag SSfg is 1 in step S3 and it is determined that it is immediately after activation, the process proceeds to step S5, and the control states of various actuators immediately after activation are determined.

  Specifically, the control signal output to the electric water pump 12a is determined so that the cooling water pumping capability of the electric water pump 12a becomes a predetermined cooling water pumping capability immediately after startup. The control signal output to the electric actuator 16b of the electric expansion valve 16 is determined so that the throttle opening of the electric expansion valve 16 is substantially fully opened.

  Furthermore, regarding the control signal output to the electric motor 14b of the compressor 14, the compressor 14 is stopped until the actual throttle opening of the electric expansion valve 16 is fully opened, that is, the rotation of the electric motor 14b. The number is determined to be zero. Further, after the actual throttle opening of the electric expansion valve 16 is fully opened, the refrigerant discharge capacity of the compressor 14 is determined to be a predetermined refrigerant discharge capacity immediately after starting.

  Note that, as described above, the electric expansion valve 16 of the present embodiment includes the electric actuator 16b formed of a stepping motor. Therefore, the electric expansion valve 16 is determined depending on the number of steps output for each control cycle. It can be easily grasped that the throttle opening is fully open.

  In step S6, after the operation of the compressor 14 is started, the increase degree ΔTd of the discharge-side refrigerant temperature Td on the discharge side of the compressor 14 is equal to or less than a predetermined reference discharge-side temperature increase degree ΔKTd. It is determined whether or not.

  As the increase degree ΔTd of the discharge-side refrigerant temperature Td, the discharge-side refrigerant temperature Td (n−1) read in the previous control step S2 from the discharge-side refrigerant temperature Td (n) read in the control step S2 this time is used. The subtracted deviation (Td (n) −Td (n−1)) or this deviation (Td (n) −Td (n−1)) is divided by the control cycle τ (for example, 10 seconds) of the control routine. Values etc. can be adopted.

  If ΔTd ≦ ΔKTd in step S6, the process proceeds to step S9. In step S9, the control signal output to the electric actuator 16b of the electric expansion valve 16 is determined by feedforward control using the incoming water temperature Twi, the boiling temperature Two, the outside air temperature Tam, the target heating temperature Tset, and the like. Then, the activation flag SSfg = 0 is set, and the process proceeds to step S10.

  On the other hand, if ΔTd ≦ ΔKTd is not satisfied in step S 6, the process proceeds to step S 7 and after the operation of the compressor 14 is started and the water passage 15 a of the water-refrigerant heat exchanger 15 enters. It is determined whether or not the increase degree ΔTwi of the incoming water temperature Twi, which is the hot water supply temperature on the side, is equal to or less than a predetermined reference inflow side temperature increase degree ΔKTwi.

  Similarly to the degree of increase ΔTd of the discharge side refrigerant temperature Td, the degree of increase ΔTwi of the incoming water temperature Twi is the same as the degree of increase ΔTd of the discharge-side refrigerant temperature Td, and the incoming water read in the previous control step S2 from the discharged water temperature Twi (n) read in the control step S2. A deviation obtained by subtracting the temperature Twi (n-1) (Twi (n) -Twi (n-1)) or a value obtained by dividing this deviation (Twi (n) -Twi (n-1)) by the control period τ. Etc. can be adopted.

  If ΔTwi ≦ ΔKTwi is satisfied in step S7, the process proceeds to step S9. On the other hand, if ΔTwi ≦ ΔKTwi is not satisfied in step S7, the process proceeds to step S8.

  In step S8, it is determined whether or not a predetermined reference time (in this embodiment, 180 seconds) has elapsed after the operation / stop switch 31 is turned on. If it is determined in step S8 that the reference time has elapsed, the process proceeds to step S9 described above. On the other hand, if it is determined in step S8 that the reference time has not elapsed, the process proceeds to step S10.

  Next, in step S10, control signals are output from the hot water storage tank side control device 20 and the heat pump side control device 21 to the various actuators so that the control states of the various actuators determined in the control steps S4 and S5 are obtained. Then, the process proceeds to step S11.

  In step S11, when the operation / stop switch 31 of the operation panel 30 is switched to stop (OFF) and a stop request signal is output, the operation of various actuators is stopped and the entire system of the heat pump hot water heater 10 is stopped. Stop. On the other hand, when the stop request signal is not output, the process returns to step S2 after waiting until a predetermined control period τ elapses.

  As described above, in the heat pump type water heater 10 of the present embodiment, when the operation / stop switch 31 of the operation panel 30 is turned on and an operation request signal is output, the start flag SSfg is set to 1 in step S1. . Therefore, in the control step S3 immediately after the operation request signal is output, it is determined that the heat pump hot water heater 10 is immediately after starting.

  And if it determines with it being immediately after starting of the heat pump type water heater 10 by step S3, before the compressor 14 act | operates and exhibits refrigerant | coolant discharge capability, the throttle opening degree of the electric expansion valve 16 will be fully opened. Become. Furthermore, after the throttle opening degree of the electric expansion valve 16 is fully opened, the compressor 14 starts operating.

  Further, after the compressor 14 starts operating, the water passage of the water-refrigerant heat exchanger 15 until the increase degree ΔTd of the discharge side refrigerant temperature Td on the discharge side of the compressor 14 becomes equal to or less than the reference discharge side temperature increase degree ΔKTd. 15a The start flag SSfg until the rise degree ΔTwi of the incoming water temperature Twi, which is the hot water temperature on the inflow side, becomes equal to or lower than the reference inflow side temperature rise degree ΔKTwi, or until the reference time elapses after the operation request signal is output. = 1 is maintained.

  In other words, until the increase degree ΔTd of the discharge side refrigerant temperature Td becomes equal to or less than the reference discharge side temperature increase degree ΔKTd, until the increase degree ΔTwi of the incoming water temperature Twi becomes equal to or less than the reference inflow side temperature increase degree ΔKTwi, or an operation request signal Until the reference time elapses after the power is output, the throttle opening of the electric expansion valve 16 is kept fully open, and the refrigerant discharge capacity of the compressor 14 is maintained at the predetermined refrigerant discharge capacity immediately after startup.

  Then, the increase degree ΔTd of the discharge-side refrigerant temperature Td is equal to or less than the reference discharge-side temperature increase degree ΔKTd, the increase degree ΔTwi of the incoming water temperature Twi is equal to or less than the reference inflow side temperature increase degree ΔKTwi, or an operation request. If at least one of the conditions for the elapse of the reference time after the output of the signal is satisfied, SSfg = 0, and control during normal operation is executed assuming that it is no longer immediately after startup.

  Further, during normal operation, the high-temperature and high-pressure refrigerant discharged from the compressor 14 flows into the refrigerant passage 15b of the water-refrigerant heat exchanger 15, and is moved from the lower side of the hot water storage tank 11 to the water passage 15a by the electric water pump 12a. Exchanges heat with the hot water supplied. Thereby, the hot water is heated, and the heated hot water is stored above the hot water storage tank 11.

  On the other hand, the high-pressure refrigerant flowing out from the water-refrigerant heat exchanger 15 is decompressed by the electric expansion valve 16 and flows into the evaporator 17. The refrigerant flowing into the evaporator 17 absorbs heat from the outside air blown from the blower fan 17a and evaporates.

  At this time, in the electric expansion valve 16, the throttle opening is adjusted so that the COP of the heat pump cycle 13 is substantially maximized, so that the heat pump cycle 13 can be operated while exhibiting a high COP. Then, the refrigerant flowing out of the evaporator 17 is sucked into the compressor 14 and compressed again. As described above, the heat pump type hot water heater 10 of the present embodiment can heat the hot water to a temperature desired by the user during normal operation.

  Here, when the heat pump cycle 13 is restarted in a short time after the operation of the heat pump cycle 13 (specifically, the compressor 14) is stopped, the refrigerant discharge port of the compressor 14 is transferred to the refrigerant inlet of the electric expansion valve 16. The high-pressure-side refrigerant pressure Ph in the cycle that reaches may suddenly rise.

  The reason is that immediately after the operation of the heat pump cycle 13 is stopped, the temperature of the compressor 14 having a large heat capacity is not sufficiently cooled. Therefore, immediately after the operation of the compressor 14, the high temperature heated by the amount of heat of the compressor 14 itself is obtained. This is because the refrigerant is discharged and the high-pressure side refrigerant pressure Ph of the cycle is increased.

  On the other hand, in the heat pump cycle 13 of this embodiment, when the heat pump cycle 13 is started, the throttle opening of the electric expansion valve 16 is fully opened before the operation of the compressor 14 is started. It is possible to reliably avoid a sudden increase in the high-pressure side refrigerant pressure Ph of the cycle during the operation of the machine 14.

  Further, the throttle opening of the electric expansion valve 16 is kept fully open until the increase degree ΔTd of the discharge-side refrigerant temperature Td becomes equal to or less than the reference discharge-side temperature increase degree ΔKTd (until ΔTd ≦ ΔKTd). As shown in the time chart of 3 (a), it is possible to suppress the rapid increase in the high-pressure side refrigerant pressure Ph of the cycle due to the rapid increase in the discharge-side refrigerant temperature Td.

  Therefore, according to the heat pump cycle 13 of this embodiment, even if the heat pump cycle is restarted in a short time after the operation of the heat pump cycle 13 is stopped, the cycle constituent devices of the heat pump cycle 13 can be protected. FIG. 3A is a schematic time chart showing changes in the discharge-side refrigerant temperature Td and the like when restarting in a short time after the operation of the heat pump cycle 13 of the present embodiment is stopped.

  Furthermore, the ability to protect the cycle-constituting equipment in this way is extremely effective in the heat pump cycle 13 that employs a high-pressure dome type compressor as in this embodiment.

  This is because, in a compressor in which the inside of the housing 14c has a high-pressure refrigerant atmosphere, such as a high-pressure dome type compressor, means such as increasing the thickness of the housing 14c are employed in order to ensure the pressure resistance of the compressor 14. Must. For this reason, the heat capacity of the so-called low-pressure dome type compressor in which the housing 14c is in a low-pressure refrigerant atmosphere is increased, and the discharge-side refrigerant temperature Td immediately after the operation of the compressor 14 is likely to occur rapidly.

  On the other hand, when the heat pump cycle is restarted after a long time has elapsed after the operation of the heat pump cycle 13 is stopped, the high-pressure side refrigerant pressure Ph of the cycle may rapidly increase. The reason is that the incoming water temperature Twi detected when the heat pump cycle 13 is restarted is not the hot water temperature in the hot water storage tank 11 but in the hot water supply pipe from the hot water storage tank 11 to the water-refrigerant heat exchanger 15. This is because the temperature of the hot water staying in the room.

  That is, the hot water supply pipe from the hot water storage tank 11 to the water-refrigerant heat exchanger 15 tends to have a low thermal insulation performance with respect to the hot water storage tank 11, so the temperature of the hot water staying in the hot water supply pipe is outside. It has dropped to about the temperature. Therefore, after the heat pump cycle 13 is restarted, when the hot water kept in the hot water storage tank 11 with high heat insulation performance reaches the water-refrigerant heat exchanger 15, the incoming water temperature Twi is rapidly increased.

  And when such a rapid increase in the incoming water temperature Twi occurs, the amount of heat that the refrigerant discharged from the compressor 14 can dissipate to the hot water in the water-refrigerant heat exchanger 15 decreases, so the discharge side refrigerant temperature Td and The high-pressure side refrigerant pressure Ph of the cycle increases.

  On the other hand, in the heat pump cycle 13 of the present embodiment, the throttle opening of the electric expansion valve 16 is fully opened until the incoming water temperature Twi becomes equal to or lower than the reference inflow side temperature rise degree ΔKTwi (until ΔTwi ≦ ΔKTwi). Since it is maintained, as shown in the time chart of FIG. 3 (b), it is possible to prevent the discharge-side refrigerant temperature Td and the high-pressure side refrigerant pressure Ph of the cycle from rapidly increasing due to the rapid increase in the incoming water temperature Tw.

  Therefore, according to the heat pump cycle 13 of the present embodiment, even if the heat pump cycle is restarted after a long time has elapsed after the operation of the heat pump cycle 13 is stopped, the cycle components of the heat pump cycle 13 can be protected. FIG. 3B is a schematic time chart showing changes in the discharge-side refrigerant temperature Td and the like when the heat pump cycle 13 of the present embodiment is stopped and restarted after a long time.

  Furthermore, the cycle component equipment can be protected in this way because, as in this embodiment, the tank unit 200 in which the hot water storage tank 11 is accommodated and the heat pump unit 300 in which the water-refrigerant heat exchanger 15 is accommodated. The heat pump type water heater 10 configured as a separate casing is extremely effective.

  This is because if the tank unit 200 and the heat pump unit 300 are configured as separate casings, the hot water supply pipe connecting the hot water storage tank 11 and the water passage 15a of the water-refrigerant heat exchanger 15 tends to be long. For this reason, hot water is likely to radiate to the outside air in the hot water pipe connecting the hot water storage tank 11 and the water passage 15a of the water-refrigerant heat exchanger 15, and the above-described rapid increase in the incoming water temperature Twi is likely to occur. is there.

  Furthermore, according to the heat pump cycle 13 of the present embodiment, when the reference time elapses after the operation request signal is output, it is possible to shift to normal operation assuming that it is not immediately after startup. Therefore, it is possible to reliably heat the hot water after the elapse of the reference time after the operation request signal is output, and bring it close to the user's desired temperature.

  Furthermore, according to the heat pump cycle 13 of the present embodiment, after the operation request signal of the heat pump cycle 13 is output, the increase degree ΔTd of the discharge side refrigerant temperature Td becomes equal to or less than the reference discharge side temperature increase degree ΔKTd, When at least one of the three conditions that the temperature ΔTwi rise degree ΔTwi is equal to or lower than the reference inflow side temperature rise degree ΔKTwi or that the reference time has elapsed after the operation request signal is output is satisfied, As described in the control step S9, the control signal output to the electric actuator 16b of the electric expansion valve 16 is determined by feedforward control.

  Therefore, the throttle opening degree of the electric expansion valve 16 can be quickly set to an appropriate value rather than determining a control signal output to the electric actuator 16b of the electric expansion valve 16 by feedback control when the normal operation is started. You can get closer.

(Other embodiments)
The present invention is not limited to the above-described embodiment, and can be variously modified as follows without departing from the spirit of the present invention.

  (1) In the above-described embodiment, after the operation request signal for the heat pump cycle 13 is output, the increase degree ΔTd of the discharge-side refrigerant temperature Td is equal to or less than the reference discharge-side temperature increase degree ΔKTd, and the increase in the incoming water temperature Twi. When the degree ΔTwi is equal to or lower than the reference inflow side temperature rise degree ΔKTwi, or when at least one of the three conditions that the reference time has elapsed after the operation request signal is output, the operation shifts to the normal operation. Although the example to do was demonstrated, this invention is not limited to this.

  For example, when a plurality of conditions among the above three conditions are satisfied, the operation may be shifted to normal operation, or only one of the conditions may be determined.

  As is apparent from the above description, when the heat pump cycle 13 is restarted in a short time after the operation of the heat pump cycle 13 is stopped, a sudden rise in the incoming water temperature Twi hardly occurs. When the cycle 13 is restarted, the discharge side refrigerant temperature Td hardly rises.

  Therefore, either the increase degree ΔTd of the discharge side refrigerant temperature Td is equal to or less than the reference discharge side temperature increase degree ΔKTd, or the increase degree ΔTwi of the incoming water temperature Twi is equal to or less than the reference inflow side temperature increase degree ΔKTwi. If the conditions are satisfied, it is possible to shift to normal operation as if both conditions are satisfied.

  (2) In the above-described embodiment, the example in which the throttle opening of the electric expansion valve 16 is fully opened when it is determined in the control step S3 that it is immediately after the start has been described. The throttle opening of the valve 16 is not limited to full opening, and is sufficient to prevent the high pressure side refrigerant pressure Ph of the cycle from rapidly increasing even if the discharge side refrigerant temperature Td or the incoming water temperature Twi increases rapidly. It is sufficient that the throttle opening is large.

  According to the study of the present inventor, in the temperature type expansion valve applied to a general heat pump cycle, the throttle opening degree of the electric type expansion valve may be set to 80% or more of the fully opened state immediately after startup. I know that.

  (3) In each of the above-described embodiments, an example in which carbon dioxide is employed as the refrigerant has been described. However, the type of refrigerant is not limited to this. Ordinary fluorocarbon refrigerants, hydrocarbon refrigerants, and the like may be employed. Furthermore, the heat pump cycle 13 may constitute a subcritical refrigeration cycle in which the high-pressure side refrigerant pressure Ph does not exceed the critical pressure of the refrigerant.

  (4) In each of the above-described embodiments, an example in which an electric compressor is employed as the compressor 14 has been described. However, the format of the compressor 14 is not limited to this. For example, you may employ | adopt the engine drive type compressor which uses an engine etc. as a drive source. Further, as the compression mechanism, not only a fixed displacement compression mechanism but also a variable displacement compression mechanism may be employed.

  (5) In each of the above-described embodiments, the example in which the electric expansion valve 16 is employed as the variable throttle mechanism has been described. However, the variable throttle mechanism is not limited to this. For example, as a variable throttle mechanism, an ejector that sucks refrigerant into the interior by a high-speed refrigerant flow that is injected from a nozzle that decompresses and expands the refrigerant, and mixes the sucked refrigerant with a high-speed refrigerant flow to increase the pressure. May be.

  (6) In each of the above-described embodiments, the example in which the heat pump cycle of the present invention is applied to the heat pump type hot water heater 10 has been described. However, the application of the present invention is not limited to this, and the amount of heat absorbed by the low-pressure refrigerant is changed to the high-pressure refrigerant. It can be widely applied to heat pump cycles that dissipate heat. For example, the present invention can be applied to an indoor heating device that heats indoor air, a heat pump floor heating device, and the like.

DESCRIPTION OF SYMBOLS 13 Heat pump cycle 14 Compressor 15 Water-refrigerant heat exchanger 16 Electric expansion valve 17 Evaporator 21a Discharge capability control means 21b Variable throttle control means 22 Discharge side temperature sensor 23 Evaporator temperature sensor 24 Outside air temperature sensor 31 Operation / stop switch 32 Hot water temperature switch

Claims (4)

A compressor (14) for compressing and discharging the refrigerant;
A heat exchanger (15) for heating that heats the fluid to be heated by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the compressor (14) and the fluid to be heated;
A variable throttle mechanism (16) configured to change a throttle opening for decompressing and expanding the high-pressure refrigerant that has flowed out of the heating heat exchanger (15);
An evaporator (17) for evaporating the refrigerant decompressed by the variable throttle mechanism (16);
Discharge capacity control means (21a) for controlling the refrigerant discharge capacity of the compressor (14);
Variable aperture control means (21b) for controlling the operation of the variable aperture mechanism (16);
A discharge side temperature detecting means (22) for detecting a discharge side refrigerant temperature (Td) on the discharge side of the compressor (14);
Request signal output means (31) for outputting an operation request signal for operating the compressor (14) to the discharge capacity control means (21a);
Target temperature setting means (32) for setting a target heating temperature (Tset) of a heating target fluid flowing out from the heating heat exchanger (15),
The variable aperture control means (21b)
When the operation request signal is output from the request signal output means (31), before the discharge capacity control means (21a) starts the operation of the compressor (14), the variable throttle mechanism (16) The throttle opening is fully open,
Further, after the start of the operation of the compressor (14), the reference discharge in which the degree of increase (ΔTd) of the discharge-side refrigerant temperature (Td) detected by the discharge-side temperature detection means (22) is determined in advance. The variable throttle mechanism (16) so that the temperature of the fluid to be heated flowing out of the heating heat exchanger (15) approaches the target heating temperature (Tset) when the temperature rises to the side temperature rise degree (ΔKTd) or less. A heat pump cycle characterized by changing the throttle opening of the cylinder. Furthermore, an inflow side temperature detecting means (25) for detecting an inflow side temperature (Twi) of the heating target fluid flowing into the heating heat exchanger (15) is provided,
The variable aperture control means (21b)
After the start of the operation of the compressor (14), the increase degree of the inflow side temperature (Twi) detected by the inflow side temperature detection means (25) is a predetermined reference inflow side temperature increase degree ( (ΔKTwi) or less, the throttle opening of the variable throttle mechanism (16) is adjusted so that the temperature of the heating target fluid flowing out of the heating heat exchanger (15) approaches the target heating temperature (Tset). The heat pump cycle according to claim 1, wherein the heat pump cycle is changed. A compressor (14) for compressing and discharging the refrigerant;
A heat exchanger (15) for heating that heats the fluid to be heated by exchanging heat between the high-temperature and high-pressure refrigerant discharged from the compressor (14) and the fluid to be heated;
A variable throttle mechanism (16) configured to change a throttle opening for decompressing and expanding the high-pressure refrigerant that has flowed out of the heating heat exchanger (15);
An evaporator (17) for evaporating the refrigerant decompressed by the variable throttle mechanism (16);
Discharge capacity control means (21a) for controlling the refrigerant discharge capacity of the compressor (14);
Variable aperture control means (21b) for controlling the operation of the variable aperture mechanism (16);
Inflow side temperature detection means (25) for detecting the inflow side temperature of the heating target fluid flowing into the heating heat exchanger (15);
Request signal output means (31) for outputting an operation request signal for operating the compressor (14) to the discharge capacity control means (21a);
Target temperature setting means (32) for setting a target heating temperature (Tset) of a heating target fluid flowing out from the heating heat exchanger (15),
The variable aperture control means (21b)
When the operation request signal is output from the request signal output means (31), before the discharge capacity control means (21a) starts the operation of the compressor (14), the variable throttle mechanism (16) The throttle opening is fully open,
Further, after the start of the operation of the compressor (14), the degree of increase of the inflow side temperature (Twi) detected by the inflow side temperature detection means (25) is a predetermined reference inflow side temperature increase. When the temperature of the fluid to be heated flowing out of the heating heat exchanger (15) approaches the target heating temperature (Tset) when the degree (ΔKTwi) or less is reached, the throttle opening of the variable throttle mechanism (16) is increased. A heat pump cycle characterized by varying degrees.   The variable throttle control means (21b) flows out of the heating heat exchanger (15) when a predetermined reference time has elapsed after the operation request signal is output from the request signal output means (31). The throttle opening degree of the variable throttle mechanism (16) is changed so that the temperature of the heating target fluid approaches the target heating temperature (Tset). Heat pump cycle.

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