JPH10205898A - Freezing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air conditioning device capable of preventing a reduction in freezing capability under an application of the most suitable value of an evaporating pressure in a freezing cycle or a nozzle efficiency. SOLUTION: A freezing cycle 9 is constructed such that a compressor 11, a condenser 12, an ejector 13 and a gas-liquid separator 14 are connected in a ring-form by a refrigerant pipe 17, a liquid refrigerant outlet section 26 of the gas-liquid separator 14 and a suction part 22 of the ejector 13 are connected by a bypass pipe 27 and an evaporator 16 is arranged at the midway part of the bypass pipe 27. A refrigerant pump 15 for forcedly supplying liquid refrigerant to the evaporator 16 is installed in the midway part of the bypass pipe 27 for connecting the liquid refrigerant outlet section 26 of the gas-liquid separator 14 and an inlet side of the evaporator 16. Then, a flow rate of refrigerant sucked into the compressor 11 is kept at a specified value in such a way that a rotational speed of the refrigerant pump 15 is controlled in response to a rotational speed of the compressor 11.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration system having a refrigeration cycle incorporating an ejector.

[0002]

2. Description of the Related Art Conventionally, Japanese Unexamined Patent Publication No. Hei 5-212421 discloses that a refrigerant compressor, a refrigerant condenser, an ejector, a first refrigerant evaporator, and a gas-liquid separator are annularly connected by refrigerant pipes, A refrigeration system having a refrigeration cycle has been proposed in which a liquid-phase refrigerant separated from a gas-phase refrigerant by a separator is sucked into a suction unit of an ejector through a pressure reducing device and a bypass pipe provided with a second refrigerant evaporator. ing.

The refrigeration cycle of the above-described conventional refrigeration system increases the refrigeration capacity of the refrigerant compressor during low-speed operation by adjusting the flow rate of the refrigerant passing through the nozzle 102 of the ejector 101, as shown in FIG. In order to make the refrigerating capacity with a margin at the time of high-speed operation, the nozzle 102 in the ejector 101 is provided with a variable throttle valve 103 for increasing or decreasing the nozzle diameter.

[0004]

However, in the prior art, a variable throttle valve 103 is installed in the nozzle 102 of the ejector 101 to adjust the dryness (or subcooling) of the inlet of the nozzle 102 to reduce the refrigerant. Since the flow rate is controlled, the nozzle outlet diameter is not always the optimum outlet diameter for the refrigerant flow rate, causing a reduction in nozzle efficiency (see FIG. 6) and a problem that sufficient refrigeration capacity cannot be obtained. Occurs.

Therefore, as shown in FIG. 7, a nozzle 105 whose nozzle outlet diameter can be varied by a needle valve 104 has been proposed.
As described above, the nozzle outlet diameter does not always become the optimum outlet diameter with respect to the refrigerant flow rate, as described above, so that the nozzle efficiency decreases (see FIG. 8). Further, when the nozzle efficiency is reduced, the flow rate of the refrigerant supplied to the second refrigerant evaporator cannot be sufficiently obtained, so that the pressure increase in the ejector 101 is reduced (see FIG. 9).
As a result, since the suction pressure of the refrigerant compressor decreases, the amount of the refrigerant circulating in the refrigeration cycle decreases, which causes a problem that the refrigeration capacity of the refrigeration cycle decreases.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a refrigerating apparatus which can secure a sufficient refrigerating capacity even when the nozzle efficiency is reduced by installing a refrigerant pump on the suction side of an ejector which does not affect the nozzle efficiency. Is to provide.
Another object of the present invention is to provide a refrigeration apparatus that can prevent a decrease in refrigeration capacity of a refrigeration cycle by using an evaporation pressure and a nozzle efficiency of the refrigeration cycle at optimal values. Another object of the present invention is to provide a refrigeration apparatus that can maintain the refrigeration capacity of the refrigeration cycle at a substantially constant value regardless of the increase or decrease in the rotation speed of the refrigerant compressor.

[0007]

According to the first aspect of the present invention, instead of providing the refrigerant flow rate adjusting means at the nozzle of the ejector, the liquid-phase refrigerant side of the gas-liquid separator of the refrigeration cycle and the suction of the ejector are provided. By providing a refrigerant pumping means for pumping the liquid-phase refrigerant in the gas-liquid separator to the refrigerant evaporator in the middle of the bypass flow path connecting the parts, the nozzle efficiency is not significantly affected. Further, by forcibly circulating the refrigerant through the refrigerant evaporator, the boosting performance is improved, and the evaporating pressure and the nozzle efficiency of the refrigeration cycle become optimal values, so that a decrease in the refrigeration capacity of the refrigeration cycle can be suppressed.

According to the second aspect of the present invention, the rotational speed of the refrigerant pump is increased or decreased so that the superheat degree on the outlet side of the refrigerant evaporator detected by the superheat degree detection means becomes a set value. Since the change in the flow rate of the refrigerant supplied to the refrigerant evaporator is suppressed, the heat transfer coefficient in the refrigerant evaporator is not significantly reduced.

According to the third aspect of the present invention, the rotational speed of the refrigerant pump is decreased as the rotational speed of the refrigerant compressor detected by the rotational speed detecting means increases.
The fluctuation of the refrigerant supplied to the refrigerant evaporator can be absorbed. Thus, by controlling the suction pressure of the refrigerant compressor, the suction specific volume of the refrigerant compressor can be changed, and the flow rate of the refrigerant sucked into the refrigerant compressor can be maintained at a substantially constant value.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION

1 to 4 show an embodiment of the present invention. FIG. 1A is a view showing a refrigeration cycle of an air conditioner for a vehicle, and FIG. 1B is a view showing a vehicle. FIG. 2 is a diagram illustrating a ventilation system of the vehicle air conditioner, and FIG. 2 is a diagram illustrating a control system of the vehicle air conditioner.

In the vehicle air conditioner of this embodiment, each air conditioning unit of the air conditioning unit 1 for air conditioning the interior of a vehicle equipped with a power engine for driving the vehicle is controlled by an air conditioning controller 10 described later. Air conditioner. The air-conditioning unit 1 includes an air-conditioning case 2 that forms an air passage for guiding conditioned air into the vehicle interior, and a blower 3 coupled to an upstream end of the air-conditioning case 2.

The air-conditioning case 2 is provided with an evaporator, which constitutes a configuration of a refrigeration cycle 9 described later, and a heater core 4 for reheating the cold air passing through the evaporator. Two air mix doors 5 that adjust the amount of air passing through the heater core 4 and the amount of air bypassing the heater core 4 are attached to the upstream side and the downstream side of the heater core 4.

The blower 3 has a centrifugal fan 6 for generating an airflow toward the passenger compartment in the air passage of the air-conditioning case 2, a blower motor 7 for rotating the centrifugal fan 6, and a rotatable centrifugal fan 6. It is composed of a scroll casing 8 to be accommodated. In addition, the scroll casing 8 is integrally connected to, for example, the upstream end of the air conditioning case 2.

Next, the configuration of the refrigeration cycle 9 of this embodiment will be described with reference to FIG. The refrigeration cycle 9 is a so-called ejector cycle, and includes a compressor (refrigerant compressor) 11 that compresses a gas-phase refrigerant (hereinafter, referred to as a gas refrigerant) by a driving force of a power engine mounted on a vehicle, and a compressed gas refrigerant. (Refrigerant condenser) 12 for condensing and liquefying the liquid, an ejector 13 for decompressing and expanding the condensed and liquefied liquid refrigerant (hereinafter, referred to as liquid refrigerant), and a gas for separating the decompressed and expanded gas-liquid two-phase refrigerant into gas and liquid. It comprises a liquid separator 14, a refrigerant pump 15 for sucking liquid refrigerant, and an evaporator (refrigerant evaporator) 16 for evaporating and evaporating the inflowing refrigerant.

The compressor 11, together with the condenser 12, the ejector 13 and the gas-liquid separator 14, are connected in a ring by a refrigerant pipe (refrigerant flow path) 17. This compressor 11 has an electromagnetic clutch (FIG. 2) for intermittently transmitting rotational power from the power engine to the compressor 11.
18) are connected. When the electromagnetic clutch 18 is energized, the rotational power of the power engine is transmitted to the compressor 11 and the evaporator 16 performs the air cooling action. In the vicinity of the condenser 12, a cooling fan 19 for sending cooling air for cooling the refrigerant flowing through the condenser 12 is provided.

The ejector 13 ejects the liquid refrigerant flowing from the condenser 12 from the nozzle 21 to atomize the gas refrigerant under reduced pressure, and at the same time, sucks the gas refrigerant from the suction part 22 to separate the liquid refrigerant and the gas refrigerant in the diffuser 23. It is a decompression unit that sends a refrigerant in a gas-liquid two-phase state to the gas-liquid separator 14 after mixing and pressurizing. The gas-liquid separator 14 has a refrigerant inlet 24, a gas refrigerant outlet 25, and a liquid refrigerant outlet (liquid-phase refrigerant side) 26.

The refrigerant pump 15 is a component corresponding to the refrigerant pumping means of the present invention, and is a liquid refrigerant outlet 26 of the gas-liquid separator 14.
The bypass pipe (bypass flow path) 27 that connects the suction port 22 of the ejector 13 with the suction section 22 is disposed upstream (at the entrance side) of the evaporator 16. By changing the ON / OFF interval, the refrigerant pump 15
This is a component for adjusting the flow rate of the refrigerant flowing into the evaporator 16. For example, the longer the ON time of the refrigerant pump 15 is, the longer the flow rate of the refrigerant flowing into the evaporator 16 becomes. The evaporator 16 is an air cooling unit that is installed in the middle of the bypass pipe 27 and exchanges heat between the refrigerant flowing inside and the air passing through the air conditioning case 2 to cool the air.

The air-conditioning control device 10 is a component corresponding to the air-conditioning control means of the present invention. The power is supplied from the battery 30 when the ignition switch is turned on, and each of the air-conditioning control devices 10 on an operation panel provided on the front of the vehicle compartment is provided. A switch signal is input from the switch to perform various control processes. A known microcomputer including a CPU, a ROM, a RAM, and the like is provided in the air-conditioning control device 10. When the relay coil 34 is energized, the relay switch 35 is closed to energize the refrigerant pump 15, and the relay coil 36 is energized. , The relay switch 37 is closed and the electromagnetic clutch 18 is energized.

The air-conditioning control device 10 has an outlet temperature sensor 31 for detecting the temperature on the outlet side of the evaporator 16 and an outlet pressure sensor for detecting the pressure on the outlet side of the evaporator 16 (low pressure of the refrigeration cycle 9, evaporating pressure). A sensor signal is input from each sensor such as a rotation speed sensor 33 for detecting the rotation speed of the compressor 32 and the like. The outlet temperature sensor 31 and the outlet pressure sensor 32 are components corresponding to the degree of superheat detection of the present invention,
Is a component corresponding to the rotation speed detecting means of the present invention.

The air-conditioning controller 10 determines the temperature of the evaporator 16 based on the temperature at the outlet of the evaporator 16 detected by the outlet temperature sensor 31 and the pressure at the outlet of the evaporator 16.
6, the superheat degree at the outlet side is calculated, and the flow rate of the refrigerant flowing into the evaporator 16 is adjusted by controlling the rotation speed of the refrigerant pump 15 so that the superheat degree becomes a set value (for example, 1 ° C. to 2 ° C.). I have to. Further, the air conditioning control device 10 inputs the rotation speed of the compressor 11 detected by the rotation speed sensor 33, and controls the rotation speed of the refrigerant pump 15 in order to absorb a variation in the refrigerant flow rate due to the rotation speed of the compressor 11. Compressor 11 and evaporator 1
The flow rate of the refrigerant flowing into 6 is adjusted.

Next, the operation of the air-conditioning unit 1 according to this embodiment will be briefly described with reference to FIGS. Here, FIG. 3 shows a state point of the refrigerant in the refrigerant circuit of the refrigeration cycle 9 in FIG. 1A on a Mollier diagram.
3 correspond to a to f on the Mollier diagram in FIG.

In FIG. 3, PH is the high pressure (condensing pressure) of the refrigeration cycle 9, PD is the suction pressure of the compressor 11, and PL is the low pressure (evaporating pressure) of the refrigeration cycle 9.
Where PS is the outlet pressure of the nozzle 21. And FIG.
Ge in the drawing is the flow rate of the refrigerant flowing into the evaporator 16 due to the suction force of the refrigerant pump 15, and Gn is the flow rate of the refrigerant due to the suction force of the compressor 11. ΔP is the boost pressure of the ejector 13, Δie is the adiabatic heat drop at the nozzle 21,
ir is a recovery amount of the compression work of the compressor 11 by the ejector 13.

The gas refrigerant which has been compressed by the compressor 11 to have a high temperature and high pressure (state point b) is condensed and liquefied by the condenser 12 to become a high temperature and high pressure liquid refrigerant (state point c) and flows into the ejector 13. . The liquid refrigerant flowing into the ejector 13 is decompressed when passing through the nozzle 21 and reaches a state point d2, and is further pressurized when passing through the diffuser 23 to become a state point d.

At this time, the gas refrigerant at the state point d 1 is supplied from the bypass pipe 27 to the suction part 22 of the ejector 13 by utilizing the pressure drop around the refrigerant which is ejected at a high speed from the nozzle 21 when the liquid refrigerant passes through the nozzle 21. Is sucked. Therefore, the liquid refrigerant flowing from the condenser 12 and the gas refrigerant sucked from the bypass pipe 27 are mixed in the diffuser 23. Thereby, the refrigerant in the gas-liquid two-phase state flowing out of the ejector 13 becomes the state points d1, d2 and the state point d determined by the refrigerant flow rate from the condenser 12 and the refrigerant flow rate from the evaporator 16.

Thereafter, the gas-liquid two-phase refrigerant flows through the refrigerant pipe 17 into the gas-liquid separator 14 from the refrigerant inlet 24 and is separated into a gas refrigerant and a liquid refrigerant. The gas refrigerant (state point a) flows out of the gas refrigerant outlet 25 of the gas-liquid separator 14 by the suction force of the compressor 11 and is sucked into the compressor 11 through the refrigerant pipe 17.

The liquid refrigerant (state point e) in the gas-liquid separator 14 is sucked by the refrigerant pump 15 and flows out of the liquid refrigerant outlet 26 of the gas-liquid separator 14 and flows into the bypass pipe 27. . Then, the liquid refrigerant flowing into the bypass pipe 27 flows into the evaporator 16 after being pressurized by the suction effect of the refrigerant pump 15 (state point f). The liquid refrigerant flowing into the evaporator 16 passes through the evaporator 16 and evaporates (state point d1).
Is sucked by the suction unit 22 of the.

Here, in order to use the nozzle efficiency of the ejector 13 at the optimum value, it is necessary to keep the flow rate of the refrigerant flowing into the evaporator 16 at a constant value.
As shown in the graph of FIG. 4, the rotation speed of the compressor 11 ranges from an idle rotation speed (for example, 800 rpm) to a rotation speed (for example, 200 rpm) corresponding to a normal running speed, as shown in the graph of FIG. fluctuate.

Therefore, in this embodiment, the compressor 11
The rotation of the refrigerant pump 15 according to the rotation speed of the compressor 11 in order to absorb the fluctuation in the flow rate of the refrigerant flowing into the evaporator 16 (see the section of the conventional example in FIG. By controlling the speed, the suction pressure of the compressor 11 is reduced (see the embodiment of FIG. 4B). As a result, the suction specific volume of the compressor 11 is increased, so that the flow rate of the refrigerant sucked into the compressor 11 is constant (FIG. 4C).
(See the section of the embodiment).

[Effects of the Embodiment] The air conditioning unit 1 using the compressor 11 which is rotated by a power engine for running the vehicle is all idling (idling speed).
There is a problem that the cooling capacity at the time of is low. As a countermeasure, energy loss at the expansion valve is recovered by the ejector 13, so that the work of the compressor 11 can be reduced and the cooling capacity can be improved by increasing the refrigerant flow rate.

However, since the refrigeration cycle 9 including the ejector 13 largely depends on the nozzle efficiency of the ejector 13, as described above, unless the nozzle efficiency and the evaporating pressure are used at the optimum values, the cooling capacity is reduced. Conversely, there is a concern that it will decrease. In this embodiment, the purpose is to solve this problem, and the nozzle efficiency is forcibly circulated to the evaporator 16 by the refrigerant pump 15 regardless of the rotational speed of the power engine (compressor 11). And the evaporating pressure are used at the optimum values (see FIG. 4A). Thereby, as shown in FIG. 4D, a decrease in the cooling capacity can be suppressed. In particular, the present embodiment can improve the cooling capacity of the compressor 11 in the low speed region as compared with the conventional example.

The operation of the refrigerant pump 15 is based on the degree of superheat (superheat) on the outlet side of the evaporator 16 calculated from the outlet temperature sensor 31 and the outlet pressure sensor 32.
The ON / OFF control may be performed at ± 1 ° C. around the normal amount of superheat (set value: for example, 10 ° C.). In addition,
The amount of superheat is not limited to 10 ° C. The smaller the superheat, the better the heat transfer coefficient to air.

[Modification] In this embodiment, the present invention is applied to a vehicle air conditioner (air conditioner). However, the present invention is also applicable to a vehicle cooling device, a vehicle refrigeration device, or a vehicle refrigeration device. good. Further, the present invention may be applied to a stationary refrigeration apparatus.

In this embodiment, the compressor 11 is rotationally driven by a power engine for driving the vehicle, but the compressor 11 may be rotationally driven by an auxiliary engine (sub-engine) different from the power engine for driving the vehicle. Also,
The compressor 11 may be rotationally driven by another driving means such as an electric motor.

In the present embodiment, the ejector 13 and the gas-liquid separator 14 are connected by the refrigerant pipe 17, but a first refrigerant evaporator may be provided in the refrigerant pipe 17.
In this case, the evaporator 16 becomes a second refrigerant evaporator. Further, between the gas-liquid separator 14 and the refrigerant pump 15,
If necessary, a pressure reducing device (fixed throttle) may be installed.

In this embodiment, the refrigerant pump 15 is installed on the bypass pipe 27 upstream of the evaporator 16. However, refrigerant pumping means such as an electric compressor is installed on the bypass pipe 27 downstream of the evaporator 16. Is also good.

[Brief description of the drawings]

FIG. 1A is a circuit diagram showing a refrigerant circuit of a refrigeration cycle, and FIG. 1B is a schematic diagram showing a ventilation system of a vehicle air conditioner (Example).

FIG. 2 is an electric circuit diagram showing a control system of the vehicle air conditioner (Example).

FIG. 3 is a Mollier diagram of a refrigeration cycle (Example).

FIG. 4 is a graph showing the relationship between the evaporating pressure, the compressor suction pressure, the refrigerant suction flow rate, and the cooling capacity with respect to the rotation speed of the compressor (Example).

FIG. 5 is a cross-sectional view showing a conventional ejector (conventional example).

FIG. 6 is a graph showing the relationship between nozzle inlet dryness and nozzle efficiency (conventional example).

FIG. 7 is a cross-sectional view showing a conventional ejector (conventional example).

FIG. 8 is a graph showing the relationship between nozzle outlet diameter and nozzle efficiency (conventional example).

FIG. 9 is a graph showing a relationship between a refrigerant flow rate of an evaporator and a boosting performance of an ejector (conventional example).

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 air conditioning unit 9 refrigeration cycle 10 air conditioning controller (air conditioning controller) 11 compressor (refrigerant compressor) 12 condenser (refrigerant condenser) 13 ejector 14 gas-liquid separator 15 refrigerant pump (refrigerant pumping means) 16 evaporator (refrigerant evaporator) 17) Refrigerant pipe (refrigerant flow path) 21 Nozzle 22 Suction part 26 Liquid refrigerant outlet part (Liquid-phase refrigerant side) 27 Bypass pipe (Bypass flow path) 31 Outlet temperature sensor (Superheat degree detection means) 32 Outlet pressure sensor (Superheat degree) Detection means) 33 Rotation speed sensor (Rotation speed detection means)

Claims (3)

[Claims] 1. A refrigerant compressor, a refrigerant condenser, an ejector and a gas-liquid separator are annularly connected by a refrigerant flow path, and a bypass pipe is provided between a liquid-phase refrigerant side of the gas-liquid separator and a suction part of the ejector. And a refrigeration apparatus having a refrigeration cycle in which a refrigerant evaporator is installed in the middle of the bypass flow path, wherein the refrigeration cycle pumps a liquid-phase refrigerant in the gas-liquid separator to the refrigerant evaporator. A refrigeration apparatus, wherein a pressure feeding means is provided in the middle of the bypass flow path. 2. The refrigeration apparatus according to claim 1, wherein the refrigerant pumping means is a refrigerant pump connected between a liquid-phase refrigerant side of the gas-liquid separator and an inlet side of the refrigerant evaporator, The refrigeration apparatus has superheat degree detection means for detecting the degree of superheat on the outlet side of the refrigerant evaporator, and adjusts the rotation speed of the refrigerant pump so that the detection value detected by the superheat degree detection means becomes a set value. A refrigeration apparatus comprising an air conditioning control means for increasing and decreasing. 3. The refrigeration apparatus according to claim 2, wherein said air conditioning control means has a rotation speed detection means for detecting a rotation speed of said refrigerant compressor, and the detected value detected by said rotation speed detection means is A refrigeration apparatus characterized in that the rotation speed of the refrigerant pump is decreased as the number of rotations increases.