JP2512986B2 - Heat pump device - Google Patents

Description

Detailed Description of the Invention [Industrial applications]

The present invention relates to a heat pump device that controls capacity.

[Prior art]

Conventionally, as a heat pump device for performing capacity control, a system shown in FIG. 6 has been known. In the figure, 1 is a compressor that compresses a refrigerant gas and outputs it as a high-pressure refrigerant gas, 2 is a condenser that radiates and liquefies the refrigerant gas from the compressor 1, and 3 is a thermal expansion that depressurizes the liquefied refrigerant Valves 4 are evaporators that absorb heat of the refrigerant that has been decompressed to become low temperature and low pressure and gasify it. The refrigerant gas gasified by the evaporator 4 is sucked into the compressor 1 to form a circulation refrigeration cycle. Reference numeral 5 denotes a temperature controller that detects the temperature of the water circulation circuit 6 by the temperature sensing cylinder 5a and instructs the apparatus to stop when the temperature reaches a preset temperature. The water circulation circuit 6 is composed of a heat exchange section 6a for exchanging heat with the evaporator 4, a radiator 6b such as a fan coil, and a pump 6c for circulating a medium such as water through the heat exchange section 6a and the radiator 6b. Has been done. In such a device (chilling unit or the like), the outputs of the compressor 1, the condenser 2, the expansion valve 3 and the evaporator 4 (hereinafter, referred to as a heat pump device) that constitute the refrigeration cycle,
If the radiator 6b side (load side) has the same capability, the equilibrium state of the refrigeration cycle can be maintained. However, when the capacity on the load side decreases, the output of the heat pump device becomes excessively large, and the water inlet temperature of the heat exchange part 6a that exchanges heat with the evaporator 4 exceeds the set temperature. To stop. After that, the water temperature on the load side again rises due to the stop of the device, the water temperature reaches the set temperature for restarting the temperature controller 5, and the operation is restarted again. In this way, the water temperature is controlled to be constant by repeating the operation / stop of the heat pump device. By the way, generally, a temperature difference occurs between the inlet side and the outlet side of the water circulation circuit 6 due to the operation / stop. In this case, in the conventional method, the inlet-outlet temperature difference of the water circulation circuit 6 that has been heat-exchanged by the operating heat pump device is set to 5 deg, and the restart temperature of the temperature controller 5 is the frequent operation of the heat pump device. − 3d above the stop temperature to prevent a stop
eg high. Therefore, the temperature change of the water circulation circuit 6 at the time of operation / stop is the inlet-outlet temperature difference plus 3 deg, resulting in a temperature difference of 8 deg.

[Problems to be Solved by the Invention]

As described above, the conventional device described above has a problem that the temperature of the water circulation circuit greatly changes due to the start / stop. As a means for reducing such a temperature change in the water circulation circuit, there is a method in which a tank is provided in the middle of the piping of the water circulation circuit 6 to increase the capacity of the water circulation circuit 6 and control the flow rate of the water circulation circuit 6. There was a practical problem such that the system of the entire device became complicated and the price rose significantly. As another method, the capacity control can be performed by, for example, driving the compressor with an inverter and changing the power supply frequency so that the heat pump device side has the capacity control function. Realization is technically difficult, and there has been a problem that the price will rise significantly. The present invention has been made to solve the above problems, and an object of the present invention is to provide a heat pump device capable of controlling the ability to reduce the temperature change of the water circulation circuit and suppressing the rise of the discharge gas temperature. And

[Means for Solving the Problems]

The present invention relates to a heat pump device having a refrigeration cycle in which a compressor, a condenser, an expansion device, and an evaporator are connected by a closed loop, and having a cooled load cooled by the evaporator. A flow rate control device connected between the outlet side of the evaporator, a bypass flow path having an on-off valve and a pressure reducing device, one end of which is connected to the suction side of the compressor and the other end of which is connected to the inlet side high pressure pipe of the expansion device; The outlet temperature of the cooled medium to the cooled load side cooled by the evaporator is detected, and the opening degree of the flow rate control device is controlled according to the difference between the detected temperature and the set temperature. And a controller for controlling the opening of the on-off valve to allow the refrigerant to flow through the bypass passage when the control value is detected and the opening of the flow rate control device becomes equal to or less than a predetermined value.

[Action]

This invention detects the water temperature at the outlet of the evaporator by the controller, controls the valve opening of the flow rate control device in accordance with the temperature difference from the preset reference temperature, and circulates it in the heat pump device. Adjust the flow rate of the existing refrigerant to maintain the set water temperature.
When the set water temperature is further approached, the valve opening of the flow rate control device becomes smaller, and the flow rate of the refrigerant circulating in the heat pump device is controlled to be maintained at a constant value. At this time, when the valve opening of the flow rate control device is minimized and the pressure is reduced, the superheat degree (superheat) of the compressor suction part tends to rise and the discharge gas temperature tends to rise. By detecting the control value and opening the opening / closing valve of the bypass flow passage, the refrigerant is supplied to the compressor suction portion through the bypass flow passage, and the superheat degree is suppressed.

【Example】

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a configuration diagram of a heat pump device according to an embodiment of the present invention. In the figure, parts that are the same as or correspond to those in FIG. 6 are assigned the same reference numerals and explanations thereof are omitted, and parts different from FIG. 6 will be mainly described. As is apparent from the figure, the sixth point is that the electric drive control valve 7, which is a flow rate control device, the controller 8 and the bypass passage 9 are provided.
Unlike the figure, the electric drive control valve 7 includes a compressor 1 and an evaporator 4.
The cooling water is controlled by adjusting the valve opening of the pipe 10 which connects between the pipes 10 to adjust the water temperature on the water circulation circuit 6 side. The controller 8 receives a signal from the detection element 8a that detects the water temperature on the outlet side of the evaporator 4, compares the signal with a preset water outlet set temperature, and outputs a control signal according to the temperature difference. Is output to control the valve opening of the electric drive control valve 7. Further, when the valve opening control voltage, which is the valve opening control value of the electric drive control valve 7, becomes equal to or higher than a certain value (7 V in this embodiment), the solenoid opening / closing valve 11 which is an opening / closing valve connected to a bypass circuit 9 described later. It outputs an "open" signal. The compressor 1, the condenser 2, the thermal expansion valve 3, the evaporator 4, and the electric drive control valve 7 constitute a heat pump device. Further, the thermal expansion valve 3 has a pressure compensation function for appropriately maintaining the superheat degree of suction in the compressor 1. The bypass flow passage 9 is a high pressure pipe on the inlet side of the thermal expansion valve 3.
It is connected between 12 and the suction side pipe 10 of the compressor 1, and is composed of a capillary tube 9a which is a pressure reducing device having a pressure reducing function and an electromagnetic opening / closing valve 11 controlled by a controller 8. FIG. 2 is a sectional view showing the details of the electric drive control valve 7. The control system 7 opens and closes the valve housing 7a, a valve hole 7c for adjusting the flow rate formed in a partition wall 7b that divides the valve housing 7a into a refrigerant inflow side and a refrigerant outflow side. Valve body 7d,
It is composed of a solenoid 7e that opens and closes the valve body 7d. Next, the third embodiment of the operation of the present embodiment configured as described above will be described.
This will be described with reference to FIGS. First, FIG. 3 shows the relationship between the valve opening degree of the electric drive control valve 7 and the water outlet temperature of the water circulation circuit 6. The set water temperature Ta of the controller 8 is the water outlet temperature Tb measured by the detection element 8a. When the temperature is higher, the valve 7d of the electric drive control valve 7 is opened, and conversely, when the set water temperature Ta approaches the water outlet temperature Tb, the valve 7d is closed to control the temperature close to the set water temperature Ta. . As the valve opening is closed, the cooling capacity and the evaporation temperature which is the refrigerant temperature in the evaporator 4 decrease. This is shown in FIGS. 4 (B) and 4 (C). When the capacity required for the heat pump device is small, the valve opening is narrowed to reduce the evaporation temperature, and the flow rate of the refrigerant circulating in the heat pump device is reduced to reduce the capacity. In this case, the evaporation pressure of the evaporator 4 is reduced and the cooling capacity is also reduced, but at the same time, the suction pressure of the compressor 1 is also reduced, so that the superheat degree of the compressor suction portion is increased at once, and eventually the compressor 1 is reduced. There is a risk that the discharge gas temperature of will rise and exceed the upper limit allowable value. That is, when the bypass passage 9 is not incorporated, the discharge gas temperature rises by the amount associated with the decrease in the evaporation pressure as shown by the broken line in FIG. 4 (A) and exceeds the upper limit allowable value. When there is 9, the refrigerant is decompressed by this, bypassed to the suction side of the compressor 1, and cooled to suppress the rise in the discharge gas temperature, as shown by the solid line in FIG. 4 (A). . FIG. 5 is a Mollier diagram showing the relationship between the absolute pressure and the enthalpy of the heat pump device having the bypass flow passage 9. As is clear from this diagram, the adiabatic compression on the Carnot cycle is from point A to point B. Then, the rise in the discharge gas temperature can be suppressed. The control of the bypass passage 9 is performed by the electromagnetic opening / closing valve 11. As shown in FIG. 4, the opening / closing of the solenoid on-off valve 11 causes the discharge gas temperature to rise in inverse proportion to the valve opening. Therefore, it may be opened just before the discharge temperature exceeds the rise. This is performed by detecting the control voltage of the electric drive control valve 7.
In this embodiment, opening / closing is controlled by a control voltage of 7 V or higher. As described above, in this embodiment, the controller 8 controls the opening degree of the electric drive control valve 7 to change the suction pressure of the compressor 1 and to increase the discharge gas temperature which is a problem when the capacity is changed. Since the bypass flow path 9 controlled by detecting the valve opening control voltage which is the valve opening control value of the control valve 7 responds to the control, it is possible to control the heat pump device capacity with high reliability and adjust the water temperature. Can be done properly.

【The invention's effect】

As described above, according to the present invention, since the flow rate control device is provided between the compressor and the evaporator and the flow rate control device is controlled by the controller, the temperature difference from the preset reference temperature is set. According to the above, it is possible to perform capacity control so as to maintain the set water temperature by automatically adjusting the opening degree in the flow rate control device as a pressure reducing device, and by providing a bypass flow passage, the compressor during capacity control is controlled. In order to suppress the rise in the discharge gas temperature, the characteristics of the flow rate control device are applied so that the refrigerant is circulated in the bypass flow passage only when the opening of the flow rate control device becomes a predetermined value or less during capacity control. It is possible to provide a highly reliable and highly efficient heat pump device. Then, the common controller controls the opening degree of the flow rate control device according to the difference between the outlet temperature of the cooled medium to the cooled load side cooled by the evaporator and the set temperature, and the flow rate control is performed. By detecting the control value of the device and controlling the on-off valve provided with a bypass flow path according to this control value, and controlling the opening of the on-off valve when the opening degree of the flow rate control device falls below a predetermined value, the bypass flow is controlled. Since the refrigerant is circulated through the passages so as to operate in a mutually related manner, when the opening degree of the flow rate control device becomes a predetermined value or less by the control of the controller, the opening / closing valve is controlled by the control voltage of the flow rate control device or the like. The discharge gas temperature of the compressor can be promptly and accurately controlled by the control value of 1), and the flow rate control device and the on-off valve are smoothly operated in close cooperation.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a heat pump device showing an embodiment of the present invention, FIG. 2 is a sectional view of an electric drive control valve in the present embodiment, and FIG. 3 is a valve opening degree of the electric drive control valve in the present embodiment. FIG. 4 is an explanatory view showing the relationship with the water outlet temperature, FIG. 4 is an explanatory view showing the relationship between the capacity at the time of capacity control in this embodiment, the discharge gas temperature, the valve opening and the evaporation temperature, and FIG. 5 is this embodiment. FIG. 6 is a configuration diagram of a conventional heat pump device. 1 ... Compressor, 2 ... Condenser, 3 ... Expansion valve, 4 ... Evaporator, 6 ... Water circulation circuit, 7 ... Electric drive control valve, 8 ...
… Controller, 9 …… Bypass flow path, 9a …… Capillary tube, 11 …… Solenoid on-off valve. The same reference numerals in the drawings indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A heat pump apparatus comprising a compressor, a condenser, an expander and an evaporator connected in a closed loop to form a refrigeration cycle, and having a cooled load cooled by the evaporator, the suction side of the compressor. And a flow rate control device connected between the outlet side of the evaporator, a bypass flow path having an on-off valve and a pressure reducing device, one end of which is connected to the suction side of the compressor and the other end of which is connected to the inlet side high pressure pipe of the expansion device, The outlet temperature of the cooled medium to the cooled load side cooled by the evaporator is detected, and the opening degree of the flow rate control device is controlled according to the difference between the detected temperature and the set temperature, and the flow rate control is performed. The control value of the device is detected, and the on-off valve is controlled according to this control value to control the opening of the on-off valve when the opening degree of the flow rate control device becomes a predetermined value or less, and the refrigerant is supplied to the bypass passage. With the controller to distribute Heat pump apparatus characterized by comprising.