JP2002320933A - Washing unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a washing unit which stops the air pollution problem from occurring by not exhausting the exhaust into the air when changing the pressure, which was impossible in the conventional washing units which emitted solvent vapor into the air. SOLUTION: A gas circulating path 21 is provided at a washing tank 12, and a refrigerant recovery device 22, a second vacuum valve 23, a second vacuum pump 24, a non-return valve 25, a storage tank 26 and a gas supplying valve 27 are provided at this gas circulating path 21. A pressurized condition under which gas, whose main component is nitrogen gas, stored in the storage tank 26 is supplied into the washing 12 tank through the gas circulating path 21; and a vacuum condition under which the gas in the washing tank is recovered into the storage tank are repeated alternately to accelerate the washing.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a type in which an object to be cleaned (work) is stored in a cleaning tank, a cleaning liquid is introduced into the cleaning tank to perform cleaning, and cleaning is promoted by changing a pressure applied to the cleaning liquid. It relates to improvement of a cleaning device.

[0002]

2. Description of the Related Art FIG. 8 is a principle diagram of a conventional cleaning apparatus.
This cleaning apparatus 100 includes a cleaning tank 102 having a lid 101.
And a cleaning liquid tank 103 for collecting the cleaning liquid, and a cleaning tank 1
02, an outside air injection pipe 104 for introducing outside air and an air supply valve 105, and an exhaust pipe 10 for exhausting gas in the cleaning tank 102.
6, a refrigerant recovery machine 107 provided in the exhaust pipe 106,
It comprises an exhaust valve 108 and a vacuum pump 109.

The operation of the cleaning device 100 will be described. First, the lid 101 is opened, the work 111 is stored in the cleaning tank 102, the lid 101 is closed, the air supply valve 105 is closed, the liquid stop valve 112 and the exhaust gas are exhausted. The valve 108 is opened, and the vacuum pump 109 is operated. Then, the internal pressure of the cleaning tank 102 becomes lower than the atmospheric pressure.
The cleaning liquid 03 moves to the cleaning tank 102.

When the liquid level 114 of the cleaning liquid 113 reaches the level shown in the figure, the liquid stop valve 112 is closed and the vacuum pump 10
The pressure in the space above the cleaning liquid 113 is reduced to 5 kPa by the evacuation action of No. 9. Next, the exhaust valve 108 is closed, the air supply valve 105 is opened, and outside air is supplied to the space above the cleaning liquid 113 to increase the pressure to 40 kPa (about 0.4 atm).

[0005] Hydrocarbon detergents are combustible and explode if mishandled. When air is blown into the cleaning agent vapor at a pressure lower than the atmospheric pressure to increase the pressure, the oxygen concentration in the gas increases and approaches the explosion limit. Therefore, danger is avoided by keeping the pressure rise to 40 kPa. This is the reason that the pressure is increased only to about 0.4 atm.

FIGS. 9 (a) to 9 (c) are illustrations of a conventional cleaning action due to pressure fluctuation. (A) shows a dead end hole 115 provided at the bottom of the work 111, and at the start of cleaning (98k
Pa), small bubbles 1 due to air that could not be exhausted
No. 16 is attached to the dead end hole 115. The number of the bubbles 116 is one for convenience, but a plurality is generally used. In (b), when the pressure applied to the cleaning liquid by evacuation reaches 40 kPa, the bubbles 116 expand. (C)
, The pressure applied to the cleaning liquid by evacuation is 5 kPa
, The bubble 116 further expands.

[0007] Thereafter, if the pressure (b) and (c) are alternately repeated by changing the pressure, the cleaning liquid 113 can be caused to act on the dead-end holes 115 due to the stirring action of the bubbles 116, so that cleaning is usually difficult. It is possible to wash even at the place. This is the effect of the cleaning method due to pressure fluctuation.

FIG. 10 is a pressure waveform diagram of the conventional cleaning method based on pressure fluctuation. If the vertical axis is the pressure applied to the cleaning liquid and the horizontal axis is time, the pressure fluctuates as shown in the figure. That is, in order to avoid an explosion, the upper limit is changed to 40 kPa.
Then, the bubble 116 expands and contracts as shown in FIGS. 9B and 9C.

[0009]

However, as shown in FIG.
As shown in (c), the expansion and contraction of the bubble 116 is insufficient,
When the dead end hole 115 is deep or large, it takes a long time for cleaning.

In FIG. 8, a vacuum valve 108 is opened for each cycle so that gas in the space above the liquid surface is pumped by a vacuum pump 109.
The exhaust air at this time contains a large amount of cleaning liquid vapor in the air. The cleaning liquid vapor is collected by the refrigerant recovery unit 107, but the unrecovered liquid reaches the outside together with the exhaust gas. This causes air pollution.

It is an object of the present invention to provide a technique capable of efficiently cleaning by preventing air pollution and expanding the pressure fluctuation range.

[0012]

According to a first aspect of the present invention, an object to be cleaned is stored in a cleaning tank, and a hydrocarbon-based or organic solvent-based cleaning liquid is introduced into the cleaning tank to perform cleaning. At the same time, in a cleaning device that promotes cleaning by changing the pressure applied to the cleaning liquid, a storage tank that stores a gas containing nitrogen gas as the main component is provided outside the cleaning tank, and the pressure applied to the cleaning liquid in the cleaning tank is extremely small. When performing, the gas exhausted from the space above the liquid level of the cleaning liquid is stored in the storage tank. It is characterized by being attached to a cleaning device.

The cleaning is promoted by alternately repeating a pressurized state in which a gas containing nitrogen gas as a main component stored in the storage tank is supplied to the cleaning tank and a vacuum state in which the gas in the cleaning tank is collected in the storage tank. That is, since the exhaust gas is not exhausted to the atmosphere when the pressure is changed, the problem of air pollution does not occur. Further, by blowing nitrogen gas into the tank, the presence of oxygen that induces an explosion can be eliminated. As described above, there is no fear that the cleaning liquid vapor explodes, and the cleaning liquid can be pressurized to the atmospheric pressure or higher, the pressure fluctuation width can be greatly increased, and the cleaning performance can be greatly improved.

A second aspect of the present invention is characterized in that the gas circulation path is provided with a nitrogen gas supply path for injecting nitrogen gas at a pressure exceeding at least atmospheric pressure.

Since nitrogen gas is collected in the storage tank, replenishment of nitrogen gas is not required in principle. However, if the cleaning cycle is continued, the gas may be reduced due to leakage of nitrogen gas or the like. Therefore, a nitrogen gas supply path is always provided in the gas circulation path.

[0016]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a principle view of a cleaning device according to the present invention. A cleaning device 10 includes a cleaning tank 1 having a lid 11.
2, a cleaning liquid tank 14 for recovering the cleaning liquid 13 and a liquid stop valve 16, an exhaust pipe 17 for first evacuating the cleaning tank 12, a first vacuum pump 18 and a first vacuum valve 19, and a cleaning tank 12. A gas circulation path 21, a refrigerant recovery device 22 provided in the gas circulation path 21, a second vacuum valve 23,
A vacuum pump 24, a check valve 25, a storage tank 26, a gas supply valve 27, and a nitrogen gas supply path 30 for supplying high-pressure nitrogen gas exceeding atmospheric pressure to the storage tank 26 (the nitrogen gas supply path 30 is a nitrogen cylinder). 31, tube 3
2. It comprises a pressure regulating valve 33. ) And the pressure regulating valve 33
, And a bubbling pipe 37 and a bubbling valve 38 extending from the storage tank 26 to the bottom of the cleaning device 10.

The operation of the cleaning tank 12 having the above configuration will be described below. In the flow described later (FIGS. 2 to 4), the first vacuum pump 18 is set to P1 and the second Pump 24 is P2, first vacuum valve 19 is V1, second vacuum valve 23 is V2, gas supply valve 27 is V3, bubbling valve 3
8 is abbreviated as V4, and the liquid stop valve 16 is abbreviated as V5.

FIG. 2 is a flow chart of a preparation process for a cleaning operation according to the present invention, where STxx indicates step numbers. This flow will be described with reference to FIG. ST01: Close all of V1 to V5. ST02: The lid is opened, a work to be cleaned is thrown in, and the lid is closed. The inside of the tank is an air atmosphere, and the pressure is atmospheric pressure (98 kPa). ST03: Open V1. ST04: 5 k in the tank by the action of P1 (first vacuum pump)
Reduce the pressure to Pa. Thus, the amount of air in the tank becomes almost zero.

ST05: V1 is closed and V5 is opened. ST06: Since the cleaning tank is at a low pressure (vacuum), the cleaning liquid in the cleaning tank moves to the cleaning tank. At this time, since the cleaning liquid is wavy, initial cleaning can be performed. ST07: When the liquid level of the cleaning liquid in the tank reaches a predetermined level, V5 is closed.

ST08: Nitrogen gas is sealed in the storage tank in advance, and V3 is opened. ST09: Nitrogen gas is blown into the space above the liquid surface to make it 130 kpa (1.32 atm) exceeding atmospheric pressure. ST10: Close V3.

FIG. 3 is a flow chart of a cleaning process by pressure fluctuation according to the present invention. ST11: Open V2. ST12: The gas in the space above the liquid level in the tank is exhausted by P2 (second vacuum pump) and sent to the storage tank. Continue until the inside of the tank reaches 5 kPa.

ST13: The exhausted gas (mainly nitrogen gas) is stored in a storage tank. Most of the cleaning liquid vapor is collected by the refrigerant recovery machine, but the remaining part reaches the storage tank. The pressure of the storage tank increases due to the pushing action of the vacuum pump. If the pressure does not reach 130 kPa, the pressure regulating valve (reference numeral 33 in FIG. 1) can be opened to replenish high-pressure nitrogen gas.

ST14: V2 is closed and V3 is opened. ST15: Then, the gas mainly composed of the nitrogen gas stored in the storage tank reaches the inside of the tank. This is because the pressure in the tank is 1
Continue until the pressure reaches 30 kPa. ST16: When the pressure reaches 130 kPa, V3 is closed. ST17: It is determined whether to end the cleaning. Generally, the cleaning is controlled by time, so if the time has not reached the predetermined time, the result is No, and ST11 to ST17 are repeated.

FIG. 4 is a waveform diagram of the pressure fluctuation according to the present invention, where the vertical axis represents the pressure in the space above the liquid surface and the horizontal axis represents time.
The tank pressure varies from 130 kPa to 5 kPa. Conventionally, the upper limit pressure was 40 kPa, but the present invention is characterized in that the use of nitrogen gas enables a significant increase in the upper limit pressure.

FIGS. 5 (a) to 5 (c) are illustrations of the cleaning action due to pressure fluctuation in the present invention. (A) shows a dead end hole 42 provided at the bottom of a work 41 as an object to be cleaned,
At the start of cleaning (98 kPa), minute air bubbles 43 that could not be exhausted are stuck to the dead ends 42.
In (b), the pressure applied to the cleaning liquid by pressurization is 130.
When the pressure reaches kPa, the bubbles 43 shrink. In (c), when the pressure applied to the cleaning liquid by evacuation becomes 5 kPa, the bubbles 43 expand significantly.

Thereafter, when the pressures are varied to alternately perform the steps (b) and (c), the cleaning liquid 13 can act on the dead-end holes 42 due to the stirring action of the bubbles 43, and it is usually difficult to perform cleaning. It is possible to wash even at the place. That is, in the present invention, since the volume of the bubble 43 in (b) and the volume of the bubble 43 in (c) change drastically, the stirring effect reaches several times that of the related art, and the cleaning time can be greatly reduced. Alternatively, since the stirring action is enhanced, it is possible to wash more details.

FIG. 6 is a diagram showing a bubbling operation according to the present invention. In the cleaning apparatus 10 of the present invention, bubbling, that is, bubbling cleaning can be performed. That is, when the inside of the tank is at a low pressure (5 kPa), when V4 is opened, the nitrogen gas in the storage tank 26 reaches the inside of the washing tank 12 and moves in the washing liquid 13 while expanding. Therefore, the cleaning liquid vibrates violently. Such bubbling may be performed independently, or may be performed in parallel with the flow of FIG.

FIG. 7 is a flowchart of the drying operation according to the present invention, and this flow is continued from FIG. ST21: Open V5 and V3. ST22: By opening V3, a downward pressure can be applied to the liquid level of the cleaning liquid, and as a result, the cleaning liquid in the tank is returned to the cleaning liquid tank. ST23: V3 and V5 are closed.

ST24: Next, V2 is opened. ST25: The pressure in the tank is reduced by P2 (second vacuum pump). ST26: The cleaning liquid attached to the work evaporates by applying a vacuum. This is called vacuum drying. ST27: The exhaust gas during this period is stored in a storage tank.
The exhaust contains cleaning liquid vapor, but does not release this vapor to the outdoors. ST28: Vacuum drying is continued until drying is completed.

ST29: When the drying is completed, V2 is closed to stop the exhaust. ST30: Open V3, return the inside of the tank to 98 kPa, and
Close. Instead of opening V3, outside air may be injected into the tank by an air supply valve (not shown). ST31: Open the door and take out the work.

As is apparent from the above flow and FIG. 1, the apparatus of the present invention uses a gas circulation path to supply a gas containing nitrogen gas as a main component stored in a storage tank to a cleaning tank, Cleaning is promoted by alternately repeating the vacuum state in which the gas in the tank is collected in the storage tank. That is, since the exhaust gas is not exhausted to the atmosphere when the pressure is changed, the problem of air pollution does not occur. In addition, since nitrogen gas is blown into the tank, there is no risk of explosion of the cleaning liquid vapor, and it is possible to pressurize the cleaning liquid above atmospheric pressure. It can be greatly improved.

In the embodiment, the nitrogen gas supply path is connected to the storage tank, but the nitrogen gas supply path may be connected to any part of the gas circulation path.

[0033]

According to the present invention, the following effects are exhibited by the above configuration. Claim 1 is a pressurized state in which a gas containing nitrogen gas stored in a storage tank as a main component is supplied to a cleaning tank using a gas circulation path, and a vacuum state in which gas in the cleaning tank is collected in the storage tank. Prompt washing alternately. That is, since the exhaust gas is not exhausted to the atmosphere when the pressure is changed, the problem of air pollution does not occur. In addition, since nitrogen gas is blown into the tank, there is no risk of explosion of the cleaning liquid vapor, and the cleaning liquid can be pressurized to a pressure higher than the atmospheric pressure. It can be greatly improved.

A second aspect of the present invention is characterized in that the gas circulation path is provided with a nitrogen gas supply path for injecting a nitrogen gas having a pressure exceeding at least atmospheric pressure. If the cleaning cycle is continued, the nitrogen gas leaks and decreases. Therefore, a stable cleaning cycle can be continued by always providing a nitrogen gas supply path in the gas circulation path.

[Brief description of the drawings]

FIG. 1 is a principle diagram of a cleaning apparatus according to the present invention.

FIG. 2 is a flowchart of a preparation process for a cleaning operation according to the present invention.

FIG. 3 is a flowchart of a cleaning process by pressure fluctuation according to the present invention.

FIG. 4 is a waveform diagram of pressure fluctuation according to the present invention.

FIG. 5 is an explanatory diagram of a cleaning action due to pressure fluctuation in the present invention.

FIG. 6 is a diagram of a bubbling operation according to the present invention.

FIG. 7 is a flowchart of a drying operation according to the present invention.

FIG. 8 is a principle diagram of a conventional cleaning device.

FIG. 9 is an explanatory view of a conventional cleaning action due to pressure fluctuation.

FIG. 10 is a pressure waveform diagram of a conventional cleaning method using pressure fluctuation.

[Explanation of symbols]

10 cleaning device, 12 cleaning tank, 13 cleaning solution, 21
Gas circulation path, 23 second vacuum valve, 24 second vacuum pump, 26 storage tank, 30 nitrogen gas supply path,
Reference numeral 31 denotes a nitrogen cylinder, 33 denotes a pressure regulating valve, 34 denotes a pressure sensor, 35 denotes a pressure controller, 41 denotes an object to be cleaned (work),
42: dead end hole, 43: air bubble.

Claims (2)

[Claims] 1. A cleaning type in which an object to be cleaned is stored in a cleaning tank, a cleaning liquid is introduced into the cleaning tank by introducing a hydrocarbon-based or organic solvent-based cleaning liquid, and cleaning is promoted by changing a pressure applied to the cleaning liquid. In the apparatus, a storage tank for storing a gas containing nitrogen gas as a main component is provided outside the cleaning tank, and when the pressure applied to the cleaning liquid in the cleaning tank is reduced, the gas exhausted from the space above the liquid level of the cleaning liquid is stored in the storage tank. A cleaning device, wherein a gas circulation path for returning gas stored in a storage tank to a space above the liquid level of the cleaning liquid when increasing pressure applied to the cleaning liquid in the cleaning tank and increasing the pressure applied to the cleaning liquid in the cleaning tank is provided in the cleaning apparatus. 2. The cleaning apparatus according to claim 1, wherein a nitrogen gas supply path for injecting a nitrogen gas at a pressure exceeding at least atmospheric pressure is provided in the gas circulation path.