JPH0225663A - Heat pump device - Google Patents

Abstract

PURPOSE:To reduce the temperature change in the water circulation line by reducing the drop in the suction pressure of the compressor at the time of its capacity control under certain conditions by controlling an electrically powered control valve disposed between compressor and evaporator by means of a controller, and providing a bypass line. CONSTITUTION:A controller 8 receives the signal from a sensor element 8a which senses the water temperature on the outlet side of the evaporator 4 for comparison with the predetermined set temperature. It then outputs the control signal in accordance with the temperature differential to control an electrically powered control valve 7 to regulate the cooling medium flow rate circulated in the heat pump device so as to maintain the water temperature at the set level. As the temperature comes close to the set level, the valve opening of the electrically powered control valve 7 is reduced so that the flow rate of the circulated cooling medium may be maintained at a constant level. When the valve opening of the control valve 7 becomes its smallest and the pressure drops, the pressure on the suction side drops significantly in a zone where the cooling medium circulation is small. At this time, however, the cooling medium temperature in the condenser 2 is detected to open a solenoid valve 10 in the bypass passage 9 so that the cooling medium may be supplied to the compressor 1 through the bypass passage 9 to avoid a suction pressure drop.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application] The present invention relates to a heat pump device that performs capacity control.

[Conventional technology]

As a conventional technique, for example, there is a heat pump device as shown in FIG. In the figure, 1 is a compressor that compresses refrigerant gas and outputs it as high-pressure refrigerant gas, 2 is a condenser that releases heat from the refrigerant gas from compressor 1 and liquefies it, and 3 is a one-degree type that reduces the pressure of the liquefied refrigerant. The expansion valve 4 is an evaporator that absorbs heat from the refrigerant that has been reduced in pressure to a low temperature and low pressure to gasify it. The refrigerant gas gasified by the evaporator 4 is sucked into the compressor 1, forming a circulating refrigeration cycle. In addition, 5 is a thermosensitive tube 5a
This is a temperature regulator that detects the temperature of the water circulation circuit 6 and instructs the device to stop when a preset temperature is reached. The water circulation circuit 6 is connected to the evaporator 4 and is of a hydraulic type in which a medium such as water is circulated between a radiator 6a such as a fan coil.

In such an apparatus, a compressor 1 that constitutes a refrigeration cycle is used. Condenser 2. @ If the output of the tensioner 3 and the evaporator 4 (hereinafter referred to as a beat pump device) and the capacity of the radiator 6a side (load side) are equivalent, the equilibrium state of the refrigeration cycle can be maintained.

However, if the capacity on the load side decreases, the output of the heat pump device becomes excessive and the water inlet temperature 5a that exchanges heat with the evaporator 4 exceeds the set temperature, so the temperature regulator 5 stops the heat pump device.

After that, when the equipment stopped, the water temperature on the load side rose again.
The water temperature reaches the temperature set for restarting the temperature controller 5, and the operation is restarted again. In this way, the water temperature is controlled to be constant by repeatedly operating and stopping the heat pump device.

By the way, generally, a temperature difference between the inlet and the outlet of the water circulation circuit 6 occurs due to operation and stoppage. In the conventional case, the temperature difference between the inlet and the outlet of the water circulation circuit 6 where heat is exchanged by the heat pump device in operation is set to 5 de, and the restart temperature of the temperature controller 5 is set to 5 de. In order to prevent operation-stoppage, the temperature is set 3 degrees higher than the stop temperature. For this reason, water circulation (i2I#J6
The temperature change was the inlet-outlet temperature difference plus 3 degrees, and the concentration difference was 8 degrees.

[Problem to be solved by the invention]

As described above, the conventional device described above has a problem in that the temperature of the water circulation circuit changes greatly due to operation and stoppage.

In order to reduce such temperature changes in the water circulation circuit, there is a method of controlling the flow rate of the water circulation circuit 6 by installing a tank in the middle of the piping so as to increase the capacity 1 of the circulating water circulation circuit 6. However, there were practical problems such as the overall system of the device was complicated, and the price increased significantly.

Another method is to provide a capacity control function on the heat bomb equipment side (for example, by driving the compressor with an inverter and varying its power frequency2, it is also possible to control the capacity. Realization was technically difficult, and the price would rise dramatically.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide a pump device that performs capacity control to reduce temperature changes in a water circulation circuit.

(Means for solving ilffl) A heat pump device according to the present invention connects a compressor, a condenser II, an expansion device, an evaporator, and a pressure reducing device in the above order through refrigerant piping, circulates a heat medium, and cycles a refrigerant cycle. In the heat pump device comprising the above-mentioned pressure reducing device, the electric gl!!!
ItxJ valve, the primary side (inlet side) and secondary side (
a bypass flow path having a pressure reducing function and an electromagnetic on-off valve connected to the outlet side), the electromagnetic on-off valve provided in this bypass flow path is opened by detecting the refrigerant condensation temperature of the IRwi device;
It should be closed.

[For production]

In this invention, the water temperature at the outlet of the evaporator is detected by the controller, and the valve opening degree of the electrically driven control valve is controlled according to the temperature difference from a preset reference temperature. Adjusts the flow rate of the refrigerant circulating through the water to maintain the set water temperature. When the set water temperature approaches, the valve opening of the electrically driven control valve is reduced to control the flow rate of the refrigerant circulating within the heat pump device to be maintained at a constant value. At this time, when the valve opening of the control valve is minimized and the pressure is reduced, the pressure on the suction side drops to the tIi end in a region where the amount of refrigerant circulation is small, but the refrigerant temperature in the condenser at this time is detected and the bypass By opening the electromagnetic on-off valve of the flow path, refrigerant is supplied to the compressor through the bypass flow path, thereby suppressing a drop in suction pressure.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
The figure is a configuration diagram of a heat pump device according to the present invention, and in FIG. 1, the same or corresponding parts as in FIG. 6 are given the same reference numerals, and the explanation thereof will be omitted. 7 is an electrically driven control valve, which is installed between the compressor 1 and the evaporator 4, and controls the cooling capacity by opening and closing the valve (ζ) to adjust the water temperature. In response to the signal from the detection element 8a that detects the water temperature on the outlet side of 4, a comparison is made between the preset water outlet settings and a control signal is output according to the temperature difference. A heat pump device is configured by a compressor 12, a condenser 2, a thermostatic expansion valve 38, an evaporator 4, and an electrically driven control valve 7.

Further, the thermostatic expansion valve 3 has a pressure compensation function for maintaining the degree of superheat of suction in the compressor 1 appropriately.

Reference numeral 9 denotes a bypass circuit connected between the primary side of the 'r4IjF&drive control valve 7 and the suction pipe of the compressor 1, and is composed of a capillary tube 9a with a pressure reducing function and an electromagnetic on-off valve 10. Reference numeral 11 denotes a temperature switch which opens the electromagnetic on-off valve 10 in response to a signal from a detection element 11a provided on the refrigerant outlet pipe of the condenser 2.

and configured to control closing.

Next, the electrically driven control valve 7 will be explained with reference to FIG.

In the figure, reference numeral 7a denotes a flow rate adjustment section that adjusts the flow rate by moving a solenoid valve up and down in response to an output signal from the controller 8.

Next, the relationship between the valve opening degree of the electrically driven control valve 7 and the water outlet temperature is shown in the second rIA.

In the figure, when the set water temperature Ta of the controller 8 is higher than the water outlet temperature Tb measured by the detection element 8a, the valve of the electrically driven control valve 7 is opened, and conversely, the set water temperature Ta is higher than the water outlet temperature Tb. When the temperature approaches Ta, the valve is closed and the water temperature is controlled to be close to the set water temperature Ta.

As the valve opening is closed, the cooling capacity and evaporation v!
The evaporation temperature, which is the temperature of the refrigerant in 4, is decreasing, and FIG. 3 shows this situation. When the capacity required of the heat pump device is small, the capacity is reduced by narrowing the valve opening, lowering the evaporation temperature, and reducing the flow rate of the refrigerant circulating through the heat pump device. In this case, the evaporation pressure is lowered and the capacity is reduced, but at the same time the suction pressure of compression@1 is also lowered, so there is no problem under normal operating conditions, but if the condensing temperature and circulating water temperature are low, the suction pressure becomes negative. There is a risk of falling below the permissible operating value of compression 8!1. Diagrams for explaining this state in detail are shown in FIG. 3, which is a characteristic diagram of changes in suction pressure, valve opening degree, and evaporation temperature during capacity control, and FIG. 4, which is a Mollier diagram. That is, if the bypass flow path 9 is not installed, the suction pressure will be lower than the allowable limit and the operation will be on the vacuum side (point A in Figure 4), but when the bypass flow path 9 is activated, the refrigerant will flow through the electrically driven control valve 7. is bypass-circulated to increase the flow rate and suppress the drop in suction pressure (point B in Figure 4). This bypass passage 9 is controlled by an electromagnetic on-off valve 10. The electromagnetic switch 10 is opened and closed by detecting the refrigerant outlet temperature of the condenser 2, that is, the condensation temperature of the refrigerant, by the temperature switch 11, and opening and closing the electromagnetic switch 10 immediately before the temperature becomes below a certain temperature, that is, when the suction pressure becomes below the limit. Just do it.

As described above, in this invention, the fjs pneumatic drive control valve 7 is controlled by the controller 8, and the suction pressure of the compressor 1 is made variable, and an extreme drop in suction pressure that becomes a problem only under specific conditions is prevented. Since this is handled by the bypass flow path 9 which is controlled by detecting the condensing temperature, it is possible to control the heat pump device with high reliability without narrowing the refrigerant flow rate adjustment range of the electrically driven control valve 7 during normal times. This allows the water temperature to be adjusted appropriately.

In the embodiment, the condensation temperature is detected at the refrigerant outlet of the condenser, but for example, in the case of an air-cooled condenser, the temperature may be replaced with the intake air temperature or the outlet air temperature. In the case of a water-cooled condenser, the same effect as described above can be obtained even if the temperature is detected instead of the cooling water outlet water temperature.

〔Effect of the invention〕

As explained above, according to the present invention, an electrically driven control valve is provided between the compressor and the evaporator, and the control valve is controlled by the controller. Capacity control i1 can be performed to maintain the set water temperature by fully automatically adjusting the opening of the electrically driven control valve as a pressure reducing device according to the temperature difference between the water temperature and the water temperature.
And by providing a bypass flow path, the pressure t when controlling the capacity under specific conditions
In order to suppress the drop in the suction pressure of machine a, we have detected the condition of the suction pressure drop by the drop in the degree of condensation N'JN, and the bypass flow path is activated only when controlling the capacity under specific conditions. without narrowing the scope of capacity control (resulting in a highly reliable and highly efficient heat pump device).

[Brief explanation of the drawing]

Fig. 1 is a block diagram of a heat bomb device according to example #r of this invention, Fig. 2 is a relation between the water outlet temperature and the valve opening of the electrically driven control valve, and Fig. 3 is a diagram showing the relationship between the suction pressure and the valve opening during capacity control. A characteristic diagram showing changes in control valve opening degree and evaporation degree, Figure 4 is a mol line diagram showing the refrigeration cycle state, Figure 5 is a sectional view of the electrically driven control valve, and Figure 6 is a conventional It is a block diagram of a heat pump apparatus. 1... Compressor, 2... Condenser, 3... Thermostatic expansion valve, 4... Evaporator, 7... Electrically driven control valve, 8...
Controller, 9... Bypass flow path, 9a... Pressure reducing device, 1
0...Solenoid on-off valve. Note that the same reference numerals in the figures indicate the same or equivalent parts.

Claims (1)

[Claims] In a heat pump device in which a compressor, a condenser, an expansion device, an evaporator, and a pressure reducing device are connected in the above order through refrigerant piping and a heat medium is circulated to form a refrigerant cycle, the pressure reducing device is cooled by the evaporator. An electrically driven control valve whose opening degree is automatically adjusted by a signal from the controller according to the temperature of the side heat medium, and connects the primary side (inlet side) and secondary side (outlet side) of this control valve. A heat pump device comprising a bypass flow path having a pressure reducing function and an electromagnetic on-off valve, and an electromagnetic on-off valve provided in the bypass flow path which is opened and closed by detecting the refrigerant condensation temperature of the condenser.