JPS6111630Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas leak inspection device for a cooling unit for inspecting whether or not there is a leakage point of refrigerant gas in the refrigerant flow path of the cooling unit.

For example, in a refrigerator, even if a very small amount of refrigerant gas leaks from the cooling unit (hereinafter referred to as a gas leak), the cooling capacity will significantly decrease during long-term use. When this gas leak is discovered at the customer's disposal, it is extremely difficult and expensive to repair it. In addition, considering that the warranty period for refrigerator users is becoming longer, reliability is strictly required to prevent gas leaks. Therefore, gas leak inspection at the manufacturing stage is one of the extremely important inspection items. In order to maintain the rated cooling capacity during the long warranty period, it is necessary to have extremely high gas leak detection accuracy, as well as rapid inspection processing capacity commensurate with the completion speed of approximately 9 seconds per cooling unit on the production line. is also required.

In order to meet the above requirements, this cooling unit is housed in a sealed chamber with helium gas sealed in its refrigerant flow path, and by creating a high vacuum in this sealed chamber, the helium gas is We have developed a gas leak inspection method that detects gas leaks and have already submitted an application.

Therefore, the purpose of this invention is to prevent dust from entering the high-sensitivity helium gas detector together with the exhaust air caused by evacuation. To provide a gas leak inspection device for a cooling unit that can reliably prevent the degree of vacuum necessary for the cooling unit from becoming unobtainable and can detect gas leaks with high accuracy.

An embodiment of the present invention will be described below with reference to the drawings. Reference numeral 1 denotes a Bell Jar, which is approximately bell-shaped as shown in the figure, and its lower end opening 2 is airtightly abutted against the upper surface of the installation table 3 via a sealing member 4 to seal it. It is moved up and down by a pneumatic cylinder 6 between a lowered position forming a chamber 5 and a raised position where the interior is opened to the atmosphere. Reference numeral 7 denotes a cooling unit, that is, an object to be inspected, which consists of a cooler 8 for the freezer compartment of a refrigerator and a cooler 9 for the refrigerator compartment, and a series of refrigerant flow paths thereof are filled with helium gas prior to the inspection. The subject 7 is placed on the installation stand 3, and then the bell gear 1 is lowered to accommodate it in the sealed chamber 5. Beljia 1
The inside of the sealed chamber 5 formed by the intake chamber 1 is
The chambers 11 set to zero are communicated via one communication path 12. In this intake chamber 10, a rough exhaust system 13 connected to a vacuum pump 12 and a pretest exhaust system 1 connected to a vacuum pump 14 are provided.
5. Main exhaust system 17 connected to vacuum pump 16 and main test exhaust system 19 connected to vacuum pump 18
are connected to each other through valves 20 to 23, respectively. 24 is a helium gas detector for printing which receives part of the exhaust gas from the pretest exhaust system 15 via a valve 25; 26 is the main test exhaust system 1;
This is a helium gas detector for this test which receives part of the exhaust gas from 9 through valve 27. 28 is a filter that prevents dust from entering the helium gas detector 26 for this test, and is connected to the inlet portion 1 of the exhaust system 19 for this test that communicates with the intake chamber 10.
It is located at 9a. In addition, each of the vacuum pumps 12,
14, 16, and 18 are operated continuously during inspection operation. Further, both the pretest exhaust system 15 and the main test exhaust system 19 correspond to the test exhaust system in the present invention.

Next, the operation of the above configuration will be explained. First of all,
The subject 7 is placed on the installation stand 3, and the bell gear 1 is lowered to accommodate the subject 7 in the sealed chamber 5. Next, open the valve 20 of the rough exhaust system 13,
The inside of the sealed chamber 5 is evacuated, that is, roughly evacuated, until the atmospheric pressure P ₁ as shown in FIG. 2 is reduced to a predetermined pressure P ₂ .
Next, open the valve 21 of the pretest exhaust system 15 to release the pressure
The vacuum is evacuated so as to maintain the temperature near P ₂ , and in this state, the valve 25 is opened to introduce a part of the discharged gas into the pretest helium gas detector 24 to detect the presence of helium gas (pretest). If helium gas is not detected in this pretest, the valve 22 of the main exhaust system 17 is immediately opened to evacuate the sealed chamber 5 so that the pressure drops from P ₂ to P ₃ , and the pressure is reduced to around P _3. When the pressure has dropped to 1,000, the valve 23 of the exhaust system 19 for this test is opened to continue evacuation to maintain the pressure at approximately _P3 , and at the same time, the valve 27 is opened and a part of the exhaust gas is converted into helium gas for this test. The gas is introduced into the detector 26, where the presence of helium gas is detected (main test). After completion of this main test, although not shown, the atmosphere communication valve is opened to return the inside of the sealed chamber 5 to atmospheric pressure, and the bell gear 1 is raised to prepare for the next test of the subject 7. The above process is shown in Figure 3.

Now, suppose there is a gas leak in the refrigerant flow path of the object 7, and if the damage causing the gas leak is large, helium gas will leak into the sealed chamber 5 even at a low vacuum level due to rough evacuation.
This is detected by a pretest, and at this time it is displayed, the inside of the sealed chamber 5 is immediately returned to atmospheric pressure, and the bell gear 1 is raised. In addition, if the damage is extremely slight, a detectable amount of helium gas cannot be expected to leak at a vacuum level of rough evacuation, but this will be detected in the next main test when the vacuum level is further increased. Of course, a gas leak message is also displayed at this time.

By the way, the helium gas detector 26 for this test
is highly sensitive to detect extremely small amounts of helium gas, and in order to maintain this sensitivity it is necessary to create a high degree of vacuum, and the intrusion of dust etc. will greatly affect the sensitivity. A filter 28 is provided to prevent the intrusion of such dust, but if this filter 28 is provided at the exhaust port of the closed chamber 5, that is, at the communication passage 12 of the intake path, the following inconvenience will occur. That is, since the sealed chamber 5 repeatedly undergoes adiabatic expansion, if a filter is provided at the exhaust port of the sealed chamber 5, dew condensation will occur, and the condensed water will evaporate as the pressure inside the sealed chamber 5 decreases. Since the water vapor has a vapor pressure that depends on the ambient temperature, it is difficult to obtain a high degree of vacuum even if the sealed chamber 5 is evacuated, and even if it is obtained, it requires a long time of evacuation and the accuracy of gas leak detection is poor. Either it will decrease or it will take a long time to detect it. On the other hand, according to the present invention, the filter 28 is provided at the inlet part 19a of the exhaust system 19 for the main test, and the pressure change in this part is between the atmospheric pressure _P1 and the pressure _P3 during the main test.
The adiabatic expansion is not a large adiabatic expansion between the pre-test pressure _P2 and the main test pressure _P3 , so there is almost no condensation on the filter 28, and the Therefore, the above-mentioned inconvenience does not occur, and highly accurate gas leak detection can be performed in a short time. It should be noted that the pretest exhaust system 15 is not required to have a very high degree of vacuum, nor is it required to have a very high detection sensitivity, so it is sufficient to provide a filter as necessary.

As described above, the present invention can provide a gas leak inspection device for a cooling unit that can bring the sealed chamber for gas leak detection of the cooling unit to a required high vacuum in a short time and improve the accuracy of gas leak detection.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of a system showing an embodiment of the present invention, FIG. 2 is a pressure characteristic diagram, and FIG. 3 is a flow chart. In the figure, 5 is a sealed chamber, 7 is a test object (cooling unit), 10 is an intake chamber, 13 is a rough exhaust system, 15 is an exhaust system for pretest, 19 is an exhaust system for main test, and 24 is a helium gas detection for pretest. vessel, 2
6 is a helium gas detector for this test, and 28 is a filter.

Claims (1)

[Scope of utility model registration request] A sealed chamber that houses a cooling unit with helium gas filled in the refrigerant flow path, an intake chamber that communicates with this sealed chamber, a rough exhaust system and a test exhaust system that communicate with this intake chamber, and a rough exhaust system that communicates with the air intake chamber. and a helium gas detector to receive a portion of the emitted gas, which is then evacuated by a test exhaust system, and is tested without installing a filter in the communication path between the intake chamber and the sealed chamber. A gas leak inspection device for a cooling unit, characterized in that it is installed at the entrance of an exhaust system.