JPS59180081A - Vacuum pump device - Google Patents

Abstract

PURPOSE:To permit effective evacuation of all of gaseous constituents with a simple structure by a method wherein at least hydrogenated metal or dehydrogenated hydrogenated metal are arranged in a vessel as an adsorbent. CONSTITUTION:A binary alloy, consisting of Zr, containing 40wt% of Zr or more, and Mn, is pulverized mechanically into 20 mesh or less and about 40g thereof im accommodated in the part of the absorbent 1 in an enclosed vessel 2 of stainless steel. The enclosed vessel 2 is evacuated through an opening and closing valve 3 by employing another vacuum pump and, further, the optimum amount of hydrogen gas is introduced into the evacuated enclosed vessel 2 through the opening and closing valve 3. Then, Zr-Mn alloy is hydrogenated and is treated by hot gas under employing a heater 6 and another vacuum pump device to effect dehydrogenation. By the adsorbing effect of the adsorbent 1, obtained by repeating several times of hydrogenation and degydrogenation, the effective evacuation of all of the gaseous constituents may be effected with the simple structure.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to vacuum pump devices, and particularly to a vacuum pump device that uses substance adsorption.

Conventional Structures and Problems Regarding vacuum pump devices, mechanical pumps for oil leakage, such as oil rotary pumps and oil diffusion pumps, have conventionally been mainstream. On the other hand, in recent years, there has been an increasing demand for equipment that produces clean vacuum without oil vapor, mainly for vacuum equipment in the semiconductor industry, energy-related vacuum equipment, vacuum equipment for analysis and research, and the like. Cryopumps and galley coupon pumps are used to obtain this clean vacuum.

Sorption pumps are common. These vacuum pumps obtain a clean vacuum by utilizing surface phenomena such as condensation and adsorption of gas molecules, but they are complicated in structure and handling, and have problems with pumping speed.

Exhaust capacity depends on working pressure (degree of vacuum) and gas composition.

Each type of pump has its own problems in terms of equipment price, etc. In order to solve these problems, J: developed an effective adsorbent and a device using that adsorbent. was highly desired.

Purpose of the Invention The present invention is an inexpensive vacuum pump that significantly solves the problems of conventional products in obtaining a clean vacuum, has a very simple configuration and handling, and effectively evacuates all gas components. It provides equipment.

Composition of the Invention The vacuum pump device of the present invention is a device for evacuation, in which at least a metal hydride or a dehydrogenated metal hydride is interposed as an adsorbent in a container, and the adsorption effect of the substance is achieved. A heating mechanism for the adsorbent is used to regenerate (activate) the adsorbent after use, and a cooling function for the adsorbent to further improve its adsorption capacity. This is a vacuum pump device equipped with.

DESCRIPTION OF THE EMBODIMENTS Certain metals or alloys thereof are known to react with hydrogen gas under certain pressure and temperature conditions to form metal hydrides. Metal hydrides have recently attracted attention as materials for storing, transporting, and refining hydrogen, and as energy conversion media that involve heat and pressure. Hydrogen in the metal hydride penetrates into the metal in atomic form to form a solid solution, causing the crystal lattice of the metal to expand and contract as hydrogen is absorbed and released. The stress caused by this expansion and contraction generally causes the metal to become pulverized.

Whether this metal has once formed a metal hydride with hydrogen gas or has been dehydrogenated by heating and degassing, this substance is extremely sensitive to various gas components. It was found that it has strong adsorption ability. The reason for this strong adsorption ability is that compared to a certain metal or its alloy, the metal hydride formed or the metal hydride itself has a strong activity that has been dehydrogenated. It is thought that this largely depends on the grain size and the state of pulverization caused by the hydrogenation treatment.

The adsorbent used in the vacuum pump device of the present invention includes:
Well-known metal hydride materials such as simple metals or alloys may be used, but considering the ultimate vacuum, those with low hydrogen dissociation equilibrium pressure are generally good, and Zr is preferable.
Single substance or Ti, Hf.

V, Nb, Ta, Cr, Mo, Mn, Fe
, Co, Ni, Pd, Cu, A7 and at least one element selected from the group consisting of rare elements and Zr.
This is a hydride of an alloy having a Zr content of 40% by weight or more, or a hydride obtained by dehydrogenating the hydride.

The adsorbent of the present invention has a strong adsorption ability for almost all gas components, but is particularly strong against hydrogen gas because it easily forms metal hydrides. It is characterized by high adsorption capacity.

Vacuum pumps that use the getter action of an alloy of Zr with additions of Al, V, etc. have been known6.
However, compared to these alloys, the adsorbent of the present invention has a strong adsorption ability because it is a hydride or one that has undergone dehydrogenation treatment.

The vacuum pump of the present invention can be used in environments ranging from atmospheric pressure to ultra-high vacuum, but the most effective way to use it is to use a primary vacuum evacuation device separate from this device to operate from atmospheric pressure to low vacuum. It is desirable to evacuate and use this device in a higher vacuum region.

Further, by being equipped with a heating means, this device can be easily regenerated by performing heating and degassing treatment in the same way as existing vacuum pumps using adsorption action. in this case,
The hydrogen gas that has formed the hydride creates a reducing atmosphere within the system, which is thought to have an effective effect on regeneration during the heating degassing process. Furthermore, by providing a means for cooling the adsorbent, this device can further enhance the adsorption ability of the adsorbent.Actual vacuum pump equipment using such an adsorbent of the present invention An example of the configuration is shown in the figure. In the figure, a metal hydride or a dehydrogenated adsorbent 1 is housed in a closed container 2, and a part of the closed container 2 is airtight with the outside and the flow of gas during evacuation, degassing, etc. is controlled. can. It is equipped with an on-off valve 3, which is the basic configuration.

In order to realize a more effective vacuum pump, it is further equipped with a sintered metal filter 4, a porous metal 6, a heating heater 6, and the like.

Among these, the sintered metal filter 4 is used as a means to prevent the adsorbent 1 from scattering to the outside, and allows gas components to pass through, but traps solid matter.

The porous metal 6 is used for the purpose of maximizing the performance of the adsorbent 1. Specifically, it has gas permeability, increases the contact surface area between the gas and the adsorbent, and , increasing the heat transfer effect during heating and cooling. The sludge heating heater 6 is used to heat the adsorbent 1 and degas it during regeneration.

The vacuum pump device used as an example will be explained in more detail. As the adsorbent 1, a binary alloy of ZrlMn was used.

The alloy composition in the case of 89wt%Zr -11wt%
It was Mn. This alloy was pulverized to less than a mechanical θ○ mesh and about 40 mm was placed in one portion of the adsorbent shown in FIG. The sealed container 2 is made of stainless steel, the sintered alloy filter 4 is made of stainless steel, and the nominal filtration accuracy is 5 microns.
As the porous metal 5, a nickel porous metal plate having micropores was used. As shown in FIG. 1, an on-off valve 3 and a heating heater 6 were also provided.

In this state, since the Zr--Mn alloy did not form hydrides, it had almost no ability as an adsorbent, so the inside of the closed container 2 was evacuated through the on-off valve 3 using another vacuum pump device. Further, an appropriate amount of hydrogen gas was introduced into the evacuated closed container through the on-off valve 3.

By introducing this hydrogen gas, the Zr-Mn alloy easily reacted with the hydrogen gas to form a metal hydride. This metal hydride was dehydrogenated by heating and degassing using a heating heater and a separate vacuum pump device. By repeating this hydrogenation and dehydrogenation process several times, the adjustment as a vacuum pump device was completed.

In order to check the performance as a vacuum pump from this state, a vacuum chamber with an internal volume of about 11 was installed at the end of the on-off valve 3.
At 0' Torr i, primary evacuation was performed using a vacuum pump using a molecular sheep adsorbent provided separately, and then the on-off valve 3 of the vacuum pump of the present invention was opened to perform evacuation. As a result, it was found that the vacuum pump of the present invention has a very high pumping speed compared to existing bulk getter pumps and the like. The ultimate degree of vacuum in this case was 5 x 10-' Torr. In this case, the temperature of the adsorbent should be at room temperature, but if the entire airtight container 2 is placed in a thermos flask containing liquid nitrogen to keep the adsorbent 1 shown in the figure at a low temperature, the degree of vacuum will further increase. The aim was to increase the number of people.

After performing vacuum evacuation several dozen times in this way, -
Next, while reducing the pressure inside the sealed container using the soap pump used for evacuation, the heating heater 6 performs heating degassing treatment for about 60 minutes.
The test was carried out at 0°C for 1 hour. 10' ゛While the pump was still alive, the pumping speed was slightly slow, but through this regeneration process, its performance as a vacuum pump was restored.
It has been confirmed that repeated regeneration treatments provide excellent longevity.

In this example, 11 wt% of Zr was added as an adsorbent.
Although the case of an alloy containing Zr--Mn is shown, it has been found that changes in the composition of this Zr--Mn-based alloy greatly affect the evacuation speed, the ultimate degree of vacuum, etc. The composition limit that is effective for a vacuum pump device is that the Zr content is at least 40% from the viewpoint of performance such as evacuation speed and ultimate vacuum degree.
wt% or more was required. Similarly, in the case of an alloy of Zr and at least one metal other than M1, the Zr content is 40w because the tendency is almost the same as in the case of Ml.
t% or more was appropriate.

In these alloys, once a hydride is formed,
However, it has been confirmed that the performance as an adsorbent is also affected by the hydrogen concentration present in the alloy. In the previous example, the case where this step of forming a hydride was carried out in the vacuum pump device was shown, but this step can be adjusted completely separately and then accommodated in the vacuum pump device of the present invention. It is also effective.

Effects of the Invention As described in Section 2, the vacuum pump device of the present invention uses an alloy hydride or a dehydrogenated product as an adsorbent for vacuum evacuation, and has the following effects. Possesses ■ It has strong adsorption ability for all gas components, and has excellent vacuum pumping performance such as pumping speed and ultimate vacuum degree. ■ It has a very large adsorption capacity, especially for hydrogen gas. ■The device has a simple configuration and is easy to handle.

■ It is recyclable and has a long lifespan. ■ Since there are no mechanically moving parts and no hydraulic fluids such as oil or mercury are used, a clean vacuum can be obtained without vibration or noise.

[Brief explanation of the drawing]

The figure is a longitudinal sectional view showing an example of the configuration of the vacuum pump device of the present invention. 1...Adsorbent, 2...Airtight container, 3.
...Opening/closing pulp, 4...Sintered alloy filter, 5...Porous metal, 6...Heating heater. Name of agent: Patent attorney Toshio Nakao and 1 other person = α
1 434-j source

Claims (4)

[Claims] (1) A container for storing at least one of a metal hydride or a dehydrogenated metal hydride as an adsorbent, and a means for removably supplying the container to the vacuum container; A vacuum pump device characterized by performing vacuum evacuation by the adsorption action of adsorbed substances. (2) The vacuum pump device according to claim 1, further comprising means for heating the adsorbent. (3) The vacuum pump device according to claim 1 or 2, characterized in that a means for cooling the adsorbent is provided. (4) The adsorbent is Zr alone or Ti, Hf,
V, Nb. Ta, Cr, Mo, Mn, Fe, Co, N
Dehydrogenation of an alloy hydride with a Zr content of 40% by weight or more, consisting of Zr and at least one element selected from the group consisting of I, Pd, Cu, All, and rare earth elements, or its hydride. The vacuum pump device according to claim 1, characterized in that the vacuum pump device has been subjected to a chemical treatment.