US2907345A - Valve control for a vacuum chamber - Google Patents

Description

. Oct. 6, 1959 R. s. RANDALL VALVE CONTROL FOR A VACUUM CHAMBER Filed April 18. 1955 United States. Patent VALVE CONTROL FOR A VACUUM CHAIVIBER Ralph S. Randall, San Francisco, Calif.

Application April 18, 1955, Serial No. 502,077

2 Claims. (Cl. 137-565) The present invention relates to improvements in a valve control for a vacuum chamber, and has particular reference to a valve control used in connection with the Vacuum Bag Sealing Machine described in my co-pending application, Serial No. 486,797, filed February 8,

1955, now Patent No. 2,833,096, grantedMay 6, 1958. In this machine, the bags are sealed in a vacuum chamber and it becomes necessary, in the operation of the machine, to open the chamber for positioning the bags therein, to close the chamber, to apply the vacuum, to perform the sealing operation, to relieve the vacuum, and to re-open the chamber for removal of the finished bags and for the introduction of new bags.

In my present invention, it is proposed to provide a suitable valve for applying and relieving the vacuum.

It is further proposed to provide a valve of the character described which is operated by the vacuum already available which considerably reduces the cost of the machine as compared with other methods heretofore used for similar purposes.

It is still further proposed to use a vacuum' tank for periodically applying vacuum to the valve for operating the same and to provide an arrangement whereby the vacuum in the tank is maintained automatically, as an incident to the operation of the machine.

Further objects and advantages of my invention will be apparent as the specification proceeds, and the new and useful features of my valve control for a vacuum chamber will be fully defined in the claims attached hereto.

The preferred form of my invention is illustrated in the accompanying drawing, forming part of this application, which shows a side view of my valve control, portions being shown in section.

While I have shown only the preferred form of the invention, it should be understood that various changes or modifications may be made within the scope of the claims hereto attached, without departing from the spirit of the invention.

Referring to the drawing in detail, my invention comprises in its principal features, a control valve 1, a vacuum tank 2, a solenoid valve 3 and connecting conduits to be described as the specification continues.

The control valve comprises a housing 4 including a generally cylindrical, vertical section 5 and a transverse head 6 threaded thereon, as at 7. The head and the upper portion of the vertical section form an upper valve chamber divided by a diaphragm into an upper portion 8 and a lower portion 9, the diaphragm presenting an open horizontal valve seat 10 between the two chambers.

The upper edge of the vertical section 5 of the housing forms a second open valve seat, which is mounted opposite the first valve seat and in spaced relation thereto.

The head 6 is in the form of a T, and has two conduits 12 and 13 projecting therefrom, the conduit 12 leading to a vacuum pump, not shown, and the conduit 13 leading to the vacuum chamber (not shown).

Below the valve seat 11, the housing is formed with a number of ports 14 leading to the atmosphere.

' pulling the latter and the plunger 20 and the valve 21' Below the ports 14, the diameter of the housing is reduced to present a waist 15, and below the waist it expands again to present a lower piston chamber 16, which has a bottom head 17 screwed thereon, as at 18. The bottom head is stepped down in diameter to receive the fitting 19. Y

A plunger 20 is slidable vertically in the waist of the housing, and has upper and lower ends extending intov the upper and lower chambers, respectively.

The upper end of the plunger carries a disc valve 21,

which is movable between the upper and lower valve. seats 10 and 11, respectively, and is provided with upper. and lower washers adapted to seal either the lower or.

The lower end of. the plunger carries a piston 22,

including a washer 22'rnovable in the chamber 16 and bearing against the wall thereof, the washer having atapered rimand being anchored to the plunger by means of two discs 23 and 24 urged upon the lower end of the plunger by a bolt 25 screwed into the plunger. A vent 25' is provided in the chamber 16 above the piston.

Upward pressure is applied to the plunger 20 by means of a spring 26 bearingagainst a shoulder 27 in the head 17 and against the bottom disc 24, so that normally the valve 21 is in its uppermost position, with its upper washer bearing, against the seat 10, which means that the passage between the conduits l2 and 13, leading to the pump and vacuum chamber, respectively, is closed,

while the passagefbetween the ports 14 and the vacuum chamber is open, allowing air to enter the vacuum chamber. v

The vacuum tank 2 is connected to the fitting 19 at the bottom of the valve housing by means of the conduit 28, causing suction to be applied to the piston 22 and downward against the tension of the spring 26, when the conduit is open.

This causes the valve to open the valve seat 10 and close the valve seat 11, establishing communication between conduits 12 and 13 and closing the passage between the ports 14 and the suction chamber.

The conduit 28 is controlled by the solenoid valve 3, which is of conventional construction, and made to open the conduit in one position to apply suction to the piston 22, and to open the valve housing side of the conduit to the atmosphere in the other position, so as to relieve the suction, as indicated by the arrows.

Vacuum is maintained in the tank 2 through the conduit 29, which connects the upper part of the tank with the upper portion 8 of the upper chamber in the valve housing, the portion 8 being in constant communication with the conduit 12 leading to the vacuum pump, so that the tank is subjected to the suction of the pump at all times.

However, when the valve seat 10 is opened and the pump is made to draw on the suction chamber, the pressure in the conduit 29 increases momentarily, and since a high vacuum is desired for the tank, I provide a check valve 30 in the conduit 29 adjacent the tank.

The check valve 30 allows air to be sucked from the tank through the conduit 29, but automatically prevents a reverse flow of the air in casethe pressure in the conduit 29 is higher than that in the tank.

In operation:

The valve at 10 is normally closed, as shown, under the pressure of the spring 26, so that there is no comrnunication between the vacuum pump (conduit 12), and the suction chamber (conduit 13). On the other hand, air from the atmosphere is free to enter the suction chamber through ports 14 and the conduit 13.

At the same time, the suction of the pump draws on Patented Oct. 6, 9"

the atmosphere to communicate with the space underneath the piston 22, so as to relieve the vacuum at that point. This condition prevails during the loading period of the vacuum bag sealing machine.

After the machine has been loaded and the operator has closed the vacuum chamber, he operates the solenoid valve 3 to open the conduit 28 and close the latter against the atmosphere. The vacuum in the tank then draws on the bottom face of the piston 22, pulling the plunger assembly downward and opening the upper valve at 10, While closing the valve at 11.

The closing of the valve at 11 blocks the flow of air from the atmosphere to the vacuum chamber, while the opening at 10 places the vacuum chamber in direct communication with the vacuum pump for evacuating the vacuum chamber.

If, at this time, the pressure in the conduit 29 increases momentarily, the vacuum in the tank 2 will remain unaffected on account of the check valve 30.

After the vacuum chamber has been evacuated and the bags have been sealed, the solenoid valve is again actuated, either manually or automatically by suitable timing means, to close the conduit 28 against the tank 2 and to open it to the atmosphere, whereby the vacuum underneath piston 22 is relieved and the spring is allowed to return the valve 21 to its normal position, as shown, to relieve the vacuum in the chamber.

I claim:

1. In combination with a vacuum chamber, a tank mounted outside the chamber, a vacuum pump having connection with the vacuum chamber, a valve housing in said connection having a diaphragm dividing the same into an upper compartment and a lower compartment, with a valve seat in said diaphragm, the upper compartment being connected to the pump and having unrestrict ed connection with the tank to maintain a vacuum in said tank, the lower compartment being connected to the vacuum chamber and to the atmosphere, a second valve 4 a seat between the lower compartmentand the atmosphere connection and arranged opposite the first valve seat, a

valve in'said lower compartment operable for closing either of the valve seats, spring means urging the valve upon the first seat, a conduit connecting the tank and the valve housing and adapted to apply suction to the valve for opening the first valve seat and closing the second valve seat, and a control element in the latter conduit adapted to render the suction means active or inactive, the connection between the upper compartment and the tank having a check valve therein operative to prevent air pumped from the vacuum chamber from entering the tank.

2. In combination with a vacuum chamber, a tank mounted outside the chamber, a vacuum pump, a valved connection between the pump and the chamber, means providing a passageway connecting said tank with the vacuum pump side of said valved connection for maintaining a vacuum in said tank, spring means for normally closing the valve, a conduit connection between the tank and the valve having a control element operable for applying suction to said valve for opening the same, and a check valve interposed in said passageway and operative to preventair from entering said tank from said valved connection.

References Cited in the file of this patent UNITED STATES PATENTS

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