Valve opened by vacuum.

The present invention relates to a vacuum valve for isolating a vacuum chamber of a vacuum pump.

To produce a suitable seal in a valve, the pressure applied to the valve seat of the valve must be significant, resulting in the need for a high power source for the operation of the movable element of the valve.

Is known, for example, a vacuum valve essentially comprising a hollow body divided into a first portion and a second portion by an internal wall, the first part being provided with a first opening for connection to an enclosure to be evacuated and a second opening, designed to be connected to the suction of a vacuum pump, a movable valve, and urged by a spring for closing the first opening being disposed in said first portion and having a tail passing through said inner wall, said shank being connected to a piston separating said second portion into two chambers one of which, that located on the side of said shank, communicating with the outside and the other is connected to an auxiliary vacuum pump for opening the valve. The piston seals between the chambers.

This known valve requires, for its opening, an auxiliary vacuum pump, such as diaphragm pump, for example, with its drive motor to compensate for the spring force which can be important.

Thus, this valve requires a bulky auxiliary equipment whose volume can be two to three times the volume of the valve itself.

The present invention aims to overcome this drawback and to propose a valve operated with depression and do not require a bulky auxiliary equipment.

The present invention thus provides a valve whose opening is operated at depression, comprising a hollow body divided eri a first portion and a second portion by an internal wall, the first part being provided with a first opening intended to be connected to a chamber to be evacuated, and a second opening for connection to the suction of a vacuum pump, a movable valve member, urged by a spring and for closing said first opening, being disposed in said first portion, said valve having a shank passing through said wall and being connected to a piston separating said second portion into two chambers, said piston providing a seal between the two chambers of which one, that located on the side of said shank and called first chamber , communicates with the outside, characterized in that the other chamber called second chamber, includes a communication port with the outside provided with closing means and in that a communication is established between said first body portion and said second chamber.

Thus, thanks to the invention, the power required to open the valve to overcome the spring force is provided by the vacuum pump itself; it is only necessary to control the opening of the valve to close the communication hole of the second chamber with the outside, which requires only limited power. is used for example a solenoid valve whose dimensions are much smaller than those of the valve itself. This solenoid valve is controlled during the startup of the vacuum pump.

In a preferred embodiment of the invention, said communication between the first body part and the second chamber is formed by a channel in said shank and opening to the outside of the piston in said second chamber.

According to another preferred feature, in the position of opening of the valve, the outlet surface of said channel in said second chamber rests against a sealing O-ring that communication.

This measure prevents the solenoid have to suffer too great a difference in pressure between the atmosphere and the pressure in the second chamber. Thus, once the vanneestouverte, pumping in this second chamber is stopped. This helps reduce the power and therefore the size of the solenoid valve.

We will now describe an exemplary embodiment of the invention with reference to the accompanying drawings wherein:<ul><li>Figure 1 shows in axial section a valve according to the invention wherein the valve is shown in open position.</li><li>2 shows the same valve in the closed position.</li><li>Figure 3 shows the same valve viewed from above.</li></ul>

The valve according to the invention comprises a hollow body 1 divided into two parts 2 and 3 by an inner wall 4.

The first part 2 is provided with a first opening 5 intended to be connected to an enclosure in which it is desired to empty, and a second opening 6 to be connected to the suction of a vacuum pump.

A movable valve 7 is disposed within the first part 2 and is subjected to the action of a spring 8.

When the valve is closed, valve 7 closes the opening 5. A seal 9 seals off the shutter.

The valve 7 is provided with a tail 10 which passes through a sealing manner the inner wall 4 which acts as a bearing for the axial displacement of the valve 7.

In the second part 3 is located a piston 11 linked to the tail by a screw 12.

This piston 11 separates the second part 3 into a first chamber 13 and a second chamber 14. The seal between the two chambers is provided by a rolling diaphragm 15 in tight elastomer on its outer periphery between the wall 4 and the cover 16 the body and its inner periphery, between the piston 11 and a washer 17.

The rolling diaphragm comprises at its outer periphery a seal 18 sealing between the outside and the inner part 3.

The first chamber 13 is communicated with the outside via an orifice 19.

The first part 2 of the body is placed in communication with the second chamber 14 of the second part 3 of the body by means of a channel 20.

This channel has a horizontal part, radially into the upper part of the valve 7 to its axis, and a vertical axial portion from said first portion to the outlet in the second chamber 14. The outlet surface of the channel 20 being formed by the surface of the head of the screw 12 which in the open position of the valve, bears against a seal 21 closing the communication between the second chamber 14 and the first part 2 of the body. The second chamber 14 further comprises an external communication performed by a channel 22 formed in the body 16 of lid 1. This channel 22 is provided with closing means, in this case a solenoid valve 23.

This solenoid valve 23 is energized during the startup of the vacuum pump connected to the opening 6 and this power has the effect of closing the channel 22.

An O-ring 24 is interposed between the wall 4 and the bottom 25 of the body 1 for sealing between the outside and the first part 2 of the body 1.

Screws 26 and 27 perform the assembly and clamping of the assembly.

The operation is as follows:<ul><li>In the closed position, Figure 2, the valve 7 is bearing on its seat, closing the opening 5. The channel 20 provides communication between the second chamber 14 and Part 2. These two cavities are at atmospheric pressure through channel 22 that is open, the solenoid valve 23 is not energized. In addition, the first chamber 13 is also at atmospheric pressure through the orifice 19. The spring 8 applies the valve on its seat.</li></ul>

At the initiation of the vacuum pump connected to the opening 6, it feeds the solenoid valve 23 which has the effect of closing the channel 22. During operation of the pump, the second chamber 14 is empty therefore through the channel 20. When the pressure differential exerted on the two faces of the piston 11, due to the fact that the first chamber 13 is always at atmospheric pressure, carries thereon an upward force sufficient to overcome the resistance of the spring 8, the valve 7 is opened and when it has reached its high position, the screw head 12 bears on the seal 21 closing the channel 20 of communication between the second room 14 and the first part 2 of the body 1. The closure of the channel 20 is not essential, but it helps, while the valve 35est already open, to avoid excessive pressure drop in the second chamber while requiring 14 a solenoid valve capable of withstanding the pressure difference between the atmosphere and the pressure. With this measure, the pressure difference supported by the solenoid valve 23 is lower and allows you to choose a very powerful and compact solenoid valve.

Closing the valve is performed by interrupting the supply of the solenoid valve 23 which causes the opening of the channel 22 and the venting of the second chamber 14.

The pressure difference between the first and second chambers 13 and 14 is zero and the spring 8 then moves the valve downward insulating the opening 5.

Such a valve is particularly suitable for isolating a chamber to be evacuated, a primary vacuum pump such as for example a vane pump. Channel 20 that challenges to stopping the pump, the valve closed, the functional part of the vacuum pump to atmospheric pressure, overcomes some incidents related to the operation of these pumps.

Thus only a small solenoid is required by the operation to the opening of the valve.

A solenoid 11 watts is sufficient when the valve is associated with a primary vacuum pump.

such a valve can also be used in combination with a high vacuum pump despite the channel 20 which, at the time of closing of the valve and before the valve 7 reaches its seat, performs communication between the atmosphere and the second part 2, provided that the spring 8 has a greater stiffness to reduce the closing time, the section of the channel 20 is sufficiently low and the chamber to be evacuated is sufficiently large size.