JP2004205067A - Device of detecting degree of superheat - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the degree of superheat by an inexpensive means in a device of detecting the degree of superheat detecting the degree of superheat of refrigerant circulating the inside of a vapour compressive refrigerator. <P>SOLUTION: The degree of superheat is detected based on the amount of the displacement of a diaphragm 13 due to a pressure difference between a pressure in an enclosed space 14 in which refrigerant of a specified mass is sealed and a pressure in an acting chamber 15 in which a refrigerant pressure on the evaporator outlet side acts on the inside thereof. Thus, the degree of superheat can be detected by the means lower in cost less than a conventional device for detecting the degree of superheat which requires a temperature sensor and a pressure sensor. The device is effective when used for the safety switch of a refrigerator for a vehicle. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a superheat degree detecting device for detecting a superheat degree of a refrigerant circulating in a vapor compression refrigerator, and is effective for use in a safety switch of a vehicle refrigerator.
[0002]
[Problems to be solved by the prior art invention]
In a conventional vehicle refrigerator, a temperature sensor for detecting the temperature of the refrigerant and a pressure sensor for detecting the pressure of the refrigerant are provided on the discharge side of the compressor, and the degree of superheat of the refrigerant discharged from the compressor is determined based on the refrigerant temperature and the refrigerant pressure. When the degree of superheat exceeds a predetermined value, the compressor is stopped by, for example, disconnecting an electromagnetic clutch to protect the compressor.
[0003]
However, since the above-described means requires two types of sensors, it is difficult to reduce the manufacturing cost of the vapor compression refrigerator.
[0004]
In view of the above points, the present invention firstly provides a novel superheat degree detection device different from the conventional one, and secondly, an object thereof is to detect the superheat degree by inexpensive means.
[0005]
[Means for Solving the Problems]
In order to achieve the above object, according to the first aspect of the present invention, the present invention is applied to a vapor compression refrigerator that transfers heat on a low temperature side to a high temperature side, and detects a superheat degree of a refrigerant. A working chamber (15) which forms a sealed space (14) in which a predetermined mass of refrigerant is sealed, and has a closed space (14) side and a pressure of the refrigerant circulating in the vapor compression refrigerator. (13), which is disposed on the side of the working chamber (15) and applies a predetermined pressure to the diaphragm (13); and a displacement for detecting the displacement of the diaphragm (13). And a detecting means (19), wherein the temperature in the closed space (14) is substantially equal to the temperature in the working chamber (15).
[0006]
As a result, in the present invention, the degree of superheat is detected by using the differential pressure between the internal pressure of the sealed space (14) and the internal pressure of the working chamber (15), so that the conventional type requiring two types of sensors is used. The superheat degree can be detected by an inexpensive means as compared with the superheat degree detection device described above.
[0007]
According to the second aspect of the present invention, the displacement detecting means (19) indirectly detects the displacement of the diaphragm (13) by detecting a pressure change in the closed space (14). is there.
[0008]
According to a third aspect of the present invention, the displacement detecting means (19) emits a signal when the diaphragm (13) is displaced by a predetermined amount or more toward the closed space (14).
[0009]
The invention described in claim 4 is characterized in that the pressure reducing means (3) for reducing the pressure of the refrigerant is integrated.
[0010]
According to a fifth aspect of the present invention, there is provided a vapor compression refrigerator including a compressor (1) for sucking and compressing a refrigerant, and transferring heat on a low temperature side to a high temperature side. And a stop means for stopping the compressor (1) when the superheat detection device (10) determines that the superheat of the refrigerant has exceeded a predetermined value. It is characterized by having.
[0011]
As a result, a vapor compression refrigerator can be obtained at low cost.
[0012]
According to a sixth aspect of the present invention, the superheat detecting device (10) detects the superheat on the low pressure side.
[0013]
Incidentally, reference numerals in parentheses of the above-mentioned units are examples showing the correspondence with specific units described in the embodiments described later.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
(1st Embodiment)
In this embodiment, a superheat degree detection device 10 according to the present invention is applied to a vehicle refrigerator (vehicle air conditioner). FIG. 1 is a schematic diagram of a vapor compression refrigerator, and FIG. FIG. 2 is a schematic diagram of a superheat detection device 10.
[0015]
As shown in FIG. 1, the vapor compression refrigerator includes a compressor 1, a radiator 2, a decompressor 3, an evaporator 4, an accumulator 5, and the like. A fixed throttle having a fixed throttle opening such as a capillary tube is employed, and is integrated with the superheat detection device 10 as described later.
[0016]
The compressor 1 operates by receiving power from a traveling engine via an electromagnetic clutch. The radiator 2 exchanges heat with outdoor air to cool the high-temperature and high-pressure refrigerant discharged from the compressor 1. High-pressure side heat exchanger.
[0017]
In the present embodiment, since chlorofluorocarbon (R134a) is used as the refrigerant and the refrigerant pressure on the high pressure side is lower than the critical pressure of the refrigerant, the enthalpy of the refrigerant is reduced while condensing in the radiator 2. For example, when the refrigerant pressure on the high pressure side is set to be equal to or higher than the critical pressure using carbon dioxide as the refrigerant, the enthalpy is reduced while the temperature is lowered without condensing the refrigerant in the radiator 2.
[0018]
The evaporator 4 is a low-pressure heat exchanger that is housed in an air-conditioning casing 6 forming an air passage that blows out into the room, absorbs heat from the air that blows into the room, and evaporates the refrigerant depressurized by the decompressor 3. The refrigerant is separated into a gas-phase refrigerant and a liquid-phase refrigerant flowing out of the evaporator 4, stores the surplus refrigerant as a liquid-phase refrigerant, and supplies the gas-phase refrigerant to the suction side of the compressor 1.
[0019]
Incidentally, in the present embodiment, the refrigerating machine oil mixed in the refrigerant is separated by the accumulator 5, and separated and extracted, and the refrigerating machine oil is returned to the compressor 1 together with the gas-phase refrigerant.
[0020]
In the air-conditioning casing 6, downstream of the air flow from the evaporator 4, a heater 7 for heating air blown into the room by using waste heat generated by the vehicle such as engine cooling water as a heat source, and a warmer passing through the heater 7 An air mix door 8 and the like for adjusting the temperature of the air blown into the room by adjusting the ratio of the amount of air to the amount of cool air bypassing the heater 7 are housed.
[0021]
Next, the superheat detection device 10 will be described with reference to FIG.
[0022]
The body 11 is a metal block in which a refrigerant passage 12 connecting the evaporator 4 and the accumulator 5 is formed. In the present embodiment, the body 11 is also formed with the decompressor 3, that is, a fixed throttle.
[0023]
The diaphragm 13 is a displaceable thin film member that constitutes a sealed space 14 in which a predetermined mass of refrigerant is sealed, and separates the sealed space 14 from a working chamber 15 in which the pressure of the refrigerant flowing out of the evaporator 4 acts. In this embodiment, a copper-based metal having excellent thermal conductivity and tensile strength such as phosphor bronze is employed.
[0024]
In the present embodiment, the diaphragm 13 is fixed by welding or brazing the two lids 16a and 16b while sandwiching the diaphragm 13 between the receiving lid 16a and the upper lid 16b. 11 and fixed.
[0025]
The coil spring 17 is disposed on the action chamber 15 side, and serves as a pressurizing unit that applies an elastic force corresponding to a predetermined pressure to the diaphragm 13 via a spring seat (spring receiver) 18. It serves as a displacement detecting means that comes into contact with the diaphragm 13 and directly detects the displacement amount of the diaphragm 13.
[0026]
Note that the detection signal of the position detection sensor 19 is input to an electronic control device that controls air conditioning equipment such as an electromagnetic clutch and the air mix door 8.
[0027]
Next, the operation of the superheat detection device 10 according to the present embodiment and the characteristic control of the vapor compression refrigerator will be described.
[0028]
A refrigerant having a predetermined mass is sealed in the closed space 14, and the diaphragm 13 and the spring seat 18 are made of metal having a high thermal conductivity so that the temperature in the closed space 14 and the temperature in the working chamber 15 are substantially equal. Because of the configuration, the pressure in the closed space 14, that is, the pressure (gas pressure) of the gas-phase refrigerant becomes a saturated gas pressure, and the saturated gas pressure of the refrigerant acts on the closed space 14 side of the diaphragm 13. On the other hand, the refrigerant pressure flowing out of the evaporator 4 and the pressure of the coil spring 17 act on the working chamber 15 side of the diaphragm 13.
[0029]
Since the amount of displacement of the diaphragm 13 is very small, the pressure by the coil spring 17 is substantially constant regardless of the position of the diaphragm 13, and the amount of pressurization by the coil spring 17 is very small to absorb manufacturing variations and the like. Therefore, the diaphragm 13 is displaced by the pressure difference between the internal pressure of the closed space 14 and the internal pressure of the working chamber 15.
[0030]
Therefore, the differential pressure between the internal pressure of the closed space 14 and the internal pressure of the working chamber 15, that is, the displacement of the diaphragm 13 changes in proportion to the degree of superheat on the refrigerant outlet side of the evaporator 4. That is, as shown in FIG. 3, the degree of superheat increases as the diaphragm 13 is displaced toward the closed space 14, and conversely, as the diaphragm 13 is displaced toward the working chamber 15 as shown in FIG. It means that the degree decreases.
[0031]
Therefore, in this embodiment, when the diaphragm 13 is displaced by a predetermined amount or more toward the closed space 14 side, it is regarded that the degree of superheat has become a predetermined value or more, and the electromagnetic clutch is turned off to stop the compressor 1.
[0032]
Next, features of the present embodiment will be described.
[0033]
In the present embodiment, the degree of superheat is detected using the differential pressure between the internal pressure of the sealed space 14 and the internal pressure of the working chamber 15, so that compared to a conventional superheat degree detection device requiring two types of sensors, The degree of superheat can be detected by inexpensive means.
[0034]
(2nd Embodiment)
In the first embodiment, the displacement amount of the diaphragm 13 is directly detected by bringing the position detection sensor 19 into contact with the diaphragm 13, but in the present embodiment, when the diaphragm 13 is displaced, the volume of the closed space 14 changes and the pressure is reduced. Therefore, instead of the position detection sensor 19, a pressure sensor 19a for detecting the pressure in the closed space 14 is disposed, and the displacement of the diaphragm 13 is indirectly detected.
[0035]
(Third embodiment)
The position detection sensor 19 according to the first embodiment continuously outputs the position of the diaphragm 13, that is, the displacement. However, in the present embodiment, the position of the diaphragm 13 is equal to or more than a predetermined value from the reference position corresponding to the superheat degree 0. The displacement detecting means is constituted by a switch that sends a signal to the electronic control unit when the displacement occurs.
[0036]
(Other embodiments)
In the above embodiment, the degree of superheat was detected on the low pressure side, but the present invention is not limited to this, and the degree of superheat may be detected on the high pressure side, that is, on the discharge side of the compressor 1.
[0037]
Further, in the above-described embodiment, the vapor compression refrigerator including the accumulator on the suction side of the compressor 1 is described. However, the present invention is not limited to this. May be a vapor compression refrigerator provided with a receiver (liquid receiver) upstream of the refrigerator.
[0038]
Further, in the above-described embodiment, the pressure reducer 3 is integrated with the superheat detection device 10, but the present invention is not limited to this. For example, a variable throttle such as a temperature-type expansion valve is separately provided. It may be provided.
[Brief description of the drawings]
FIG. 1 is a schematic view of a vapor compression refrigerator according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of the superheat detection device according to the first embodiment of the present invention.
FIG. 3 is a cross-sectional view of the superheat detection device according to the first embodiment of the present invention.
FIG. 4 is a cross-sectional view of the superheat detection device according to the first embodiment of the present invention.
FIG. 5 is a sectional view of a superheat detection device according to a second embodiment of the present invention.
[Explanation of symbols]
3 ... throttle, 10 ... superheat detection device, 11 ... body, 12 ... refrigerant passage,
13: diaphragm, 14: closed space, 15: working chamber,
17: coil spring, 18: spring seat.

Claims (6)

A superheat degree detection device that is applied to a vapor compression refrigerator that moves heat on a low temperature side to a high temperature side and detects a superheat degree of a refrigerant,
Displacement that constitutes a closed space (14) in which a refrigerant of a predetermined mass is sealed, and separates the closed space (14) from the working chamber (15) to which the pressure of the refrigerant circulating in the vapor compression refrigerator acts. A possible diaphragm (13),
Pressurizing means (17) arranged on the side of the working chamber (15) for applying a predetermined pressure to the diaphragm (13);
Displacement detecting means (19) for detecting displacement of the diaphragm (13) is provided so that the temperature in the closed space (14) and the temperature in the working chamber (15) are substantially equal. A superheat degree detection device characterized by the above-mentioned. The superheat degree according to claim 1, wherein the displacement detecting means (19) indirectly detects a displacement of the diaphragm (13) by detecting a pressure change in the closed space (14). Detection device. The degree of superheat detection according to claim 1 or 2, wherein the displacement detecting means (19) emits a signal when the diaphragm (13) is displaced by a predetermined amount or more toward the closed space (14). apparatus. The degree of superheat detection according to any one of claims 1 to 3, wherein a pressure reducing means (3) for reducing the pressure of the refrigerant is integrated. A vapor compression refrigerator including a compressor (1) for sucking and compressing a refrigerant, and transferring heat on a low temperature side to a high temperature side,
A superheat detection device (10) according to any one of claims 1 to 4,
A vapor compression refrigeration system comprising: a stop means for stopping the compressor (1) when the superheat degree detection device (10) determines that the superheat degree of the refrigerant exceeds a predetermined value. Machine. The vapor compression refrigerator according to claim 5, wherein the superheat detection device (10) detects the superheat on the low pressure side.

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