Background Art Generally, vacuum gate valves are used to open or close a passage when a vacuum working environment is required. That is, when a special working environment is required wherein pressures of the left and right sides of the vacuum gate valve are different from each other, such a vacuum gate valve is used to allow operations to be performed even under such an uneven vacuum pressure state.

The conventional vacuum gate valves as stated above, however, have problems that a lifting mechanism installed for raising or lowering a valve body is constructed from a plurality of linked components and the whole structure of the valve is complex. Especially, the conventional vacuum gate valve has a weak point in relation to the operating structure of its pressure applying mechanism for maintaining the air-tightness between the valve body and a passage formed at its valve housing. This weak point results in unreliability of an air-tightness maintaining effect, thereby degrading operational effects. Nevertheless, no means for solving the above problems have been developed until now.

Currently, as operating means for maintaining the air-tightness between the valve body and passage formed at the valve housing, a mechanism, which is adapted to allow a pressure to be selectively applied to or removed from the valve body according to the raising or lowering of the valve body, is operatively installed inside the valve housing. This mechanism, however, is constructed not to uniformly apply the pressure on the whole portion of an O-ring installed at the valve body, but to cause the valve body to operate in a lopsided state. As a result, the air-tightness effect of the O-ring acting as air-tightness retaining means is partially weakened, thereby degrading operational effects.

According to the conventional vacuum gate valve, moreover, a guide of the valve body inaccurately operates during the raising or lowering operations and pressurizing operation of the valve body, thereby often causing various problems including the deterioration of operating efficiency and the generation of noise during operation.

Disclosure of the Invention Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to construct a pressure applying mechanism of a valve body provided in a vacuum gate valve as a single bellows unit or multiple bellows units, air bag and so on, different from existing mechanisms, thereby enabling the air-tightness between the valve body and a passage formed at a valve housing to be more uniformly and reliably maintained.

It is another object of the present invention to enable a lifting mechanism for raising or lowering a valve body and a pressure applying mechanism for applying a pressure to the valve body to be more reliably guided by guide mechanisms having a different shape than existing guide mechanisms and thus to be more accurately operated, thereby improving the reliability of operation and preventing the generation of noise during operation.

In accordance with the present invention, the above and other objects can be accomplished by the provision of a vacuum gate valve comprising a valve body installed to be raised or lowered by a lifting mechanism within a valve housing, the valve body being adapted to open or close a passage formed at the valve housing according to operation of a pressure applying mechanism installed at one side of the valve housing, the vacuum gate valve further comprising: a pneumatic transmission mechanism installed at the other side of the valve housing and adapted to transmit a pneumatic pressure to the pressure applying mechanism; and a horizontal guide mechanism coupled to the valve body to guide the valve body to slide in a horizontal direction when the valve body opens or closes the passage.

Preferably, the pressure applying mechanism of the vacuum gate valve may comprise a bellows, a plurality of bellows units or an air bag, adapted to be expanded and constricted by the pneumatic pressure transmitted from the pneumatic transmission mechanism, thereby displacing the valve body.

Preferably, the vacuum gate valve may further comprise a vertical guide mechanism for guiding raising or lowering movement of the valve body, the vertical guide mechanism including a guide rod connected at one end thereof to the horizontal guide mechanism, and operatively connected at the other end thereof to the lifting mechanism.

Preferably, the pneumatic transmission mechanism of the vacuum gate valve may comprise a pneumatic transmission block mounted to the one end of the guide rod while supporting the horizontal guide mechanism, the pneumatic transmission block having a passage communicating with the pressure applying mechanism, and a pneumatic connector connected to the pneumatic transmission block while having a passage for communicating the passage of the pneumatic transmission block with an exterior pneumatic supply line. The lifting mechanism may further comprise a pneumatic cylinder having a piston rod. The pneumatic connector may extend through the pneumatic cylinder so that a portion of the pneumatic connector positioned within the pneumatic cylinder constitutes the piston rod.

Preferably, a portion of the pneumatic connector positioned within the valve housing may constitute the guide rod of the vertical guide mechanism, and the horizontal guide mechanism may comprise a horizontal guide plate mounted to the pneumatic transmission block, and slidably engaged with a lower end of the valve body to guide the sliding movement of the valve body thereon.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is a sectional view illustrating an assembled state of a valve in accordance with the present invention; Fig. 2 is a sectional view taken along a line of 11-11 shown in Fig. 1; Fig. 3 is a longitudinal sectional view illustrating another embodiment of the valve shown in Figs. 1 and 2; Fig. 4 is a sectional view illustrating an assembled state of a further modified embodiment of the present invention; Fig. 5 is a sectional view taken along a line of V-V shown in Fig. 4;

Fig. 6 is a sectional view taken along a line of VI-VI shown in Fig. 5; Fig. 7 is a longitudinal sectional view taken along a line of VII-VII shown in Fig. 4, illustrating another modified embodiment of the present invention in which a pneumatic transmission mechanism is formed in a guide rod; Fig. 8 is a longitudinal sectional view corresponding to Fig. 7, illustrating still another modified embodiment of the present invention; Figs. 9 and 10 are views illustrating yet another modified embodiment of the present invention in which a forcible reversion mechanism of a valve body is separately installed, respectively, Fig. 9 being a sectional view taken along a line of IX-IX shown in Fig. 4, Fig. 10 being a sectional view corresponding to Fig. 4.

Best Mode for Carrying Out the Invention As shown in Figs. 1 to 10, a vacuum gate valve, conventionally, is constructed to have a valve housing 1, and a valve body 2 installed to be raised or lowered by a lifting mechanism 3 within the valve housing 1. The valve body 2 is adapted to open or close a passage 10 formed at the valve housing 1 according to the operation of a pressure applying mechanism 4 installed at one side of the valve housing 1, more particularly, at the rear side of the valve body 2. In accordance with the present invention, at the other side of the valve housing 1, a pneumatic transmission mechanism 5 is installed to transmit a pneumatic pressure to the pressure applying mechanism 4. In addition, a horizontal guide mechanism 7 is coupled to the valve body 2 to guide the valve body 2 to slide in a horizontal direction when the valve body 2 opens or closes the passage 10 formed at the valve housing 1. The pressure applying mechanism 4 comprises a flexible bellows 40 adapted to be expanded and constricted by the pneumatic pressure transmitted from the pneumatic transmission mechanism 5, thereby displacing the valve body 2.

Alternatively, the pressure applying mechanism 4 may comprise a plurality of flexible bellows units 40a as shown in Figs. 4 to 7, or a flexible air bag 42 as shown in Fig. 8, each being adapted to be expanded and constricted by the pneumatic pressure transmitted from the pneumatic transmission mechanism 5, thereby displacing the valve body 2.

The vacuum gate valve of the present invention further comprises a vertical guide mechanism 6 for guiding the raising or lowering movement of the valve body 2. The vertical guide mechanism 6 comprises a guide rod 60, which is connected

at one end thereof to the horizontal guide mechanism 7, and operatively connected at the other end thereof to the lifting mechanism 3.

The pneumatic transmission mechanism 5, as shown in Figs. 1 to 10, comprises a pneumatic transmission block SO and a pneumatic connector 52 connected to the pneumatic transmission block 51. The pneumatic transmission block 50 is mounted to the one end of the guide rod 60 while supporting the horizontal guide mechanism 7, and has a supply passage 51 communicating with the pressure applying mechanism 4. The pneumatic connector 52 is formed with a supply passage 53 for communicating the supply passage 51 of the pneumatic transmission block 50 with an exterior pneumatic supply line 54. The lifting mechanism 3 comprises a pneumatic cylinder 30 having a piston rod 32.

Alternatively, the pneumatic connector 52 extends through the pneumatic cylinder 30 so that a portion of the pneumatic connector 52 positioned within the pneumatic cylinder 30 constitutes the piston rod 32. The exterior pneumatic supply line 54 is provided with a control valve 56, which serves to apply a pneumatic pressure to the supply passage 53 or to remove the interior pneumatic pressure of the supply passage 53, thereby maintaining the supply passage 53 at atmospheric pressure.

As shown in Figs. 3,4, 6 to 8 and 10, a portion of the pneumatic connector 52 positioned within the valve housing 1 constitutes the guide rod 60 of the vertical guide mechanism 6. The horizontal guide mechanism 7 comprises a horizontal guide plate 70 mounted to the pneumatic transmission block 50, and slidably engaged with a lower end of the valve body 2 to guide the sliding movement of the valve body 2 thereon.

Preferably, in order to secure highly reliable air-tightness inside the valve housing 1, a bellows-shaped air-tightness retaining member 8 is installed in the valve housing 1 between the valve body 2 and pneumatic transmission block 50 while surrounding the piston rod 32 and guide rod 60.

After the closing operation of the valve body 2 is performed according to the expansion of the bellows 40, bellows units 40a or air bag 42 acting as the pressure applying mechanism 4, as the pneumatic operation of the pneumatic transmission mechanism 5 is released, the pressure applying mechanism 4 is returned to its original position by its own elasticity, thereby allowing the opening operation of the valve body 2 to be performed again. On the other hand, in the case that the elasticity of the pressure applying mechanism 4 is insufficient to overcome a pressure difference between the interior and exterior of the vacuum gate valve, a

separate returning mechanism 9 may be preferably installed to the pressure applying mechanism 4 for returning the pressure applying mechanism 4 to the original state thereof, thereby returning valve body 2 to its original position.

As an example of the returning mechanism 9, as shown in Fig. 9, an elastic returning member 90, such as springs, is installed between the valve body 2 and horizontal guide mechanism 7. In the case that the closing operation of the valve body 2 is performed according to the expansion of the pressure applying mechanism 4 and then the opening operation of the valve body 2 is performed according to the constriction of the pressure applying mechanism 4, the elastic returning member 90 is adapted to cause the valve body 2 to be forcibly returned to its original position As another example of the returning mechanism 9, as shown in Fig. 10, the returning mechanism 9 comprises a first pneumatic supply line 54 communicating with the pneumatic transmission mechanism 5 at one end thereof, a direction change control valve 57 installed at the other end of the first pneumatic supply line 54, a second pneumatic supply line 58 extending from the control valve 57 to a pneumatic supply compressor 55, and a vacuum line 59 extending from the control valve 57 to a vacuum pump 92. Where the bellows 40, bellows units 40a or air bag 42 acting as the pressure applying mechanism 4 communicates with the pneumatic supply line 58 according to the direction change operation of the control valve 57, the pressure applying mechanism 4 is affected by a pneumatic pressure, thereby causing the valve body 2 to perform its closing operation according to the expansion of the pressure applying mechanism 4. Where the pressure applying mechanism 4 communicates with the vacuum line 59 according to the direction change operation of the control valve 57, the pressure applying mechanism 4 is affected by a negative vacuum pressure generated by the vacuum pump 92, thereby causing the valve body 2 to perform its opening operation according to the constriction of the pressure applying mechanism 4.

A reference numeral 20, not described above, presents an O-ring to be installed to the valve body 2.

Now, the operating procedure of the vacuum gate valve in accordance with the present invention is described.

Where the vacuum gate valve of the present invention is installed at a desired region for use, the operating condition of the vacuum gate valve is considered in relation to a closed or opened state of the passage 10.

When it is desired to seal the vacuum gate valve by closing the passage 10 formed at the valve housing 1, the pressure applying mechanism 4 is maintained in a non-pressurized state not transmitting the pneumatic pressure, and the pneumatic cylinder 30 acting as the lifting mechanism 3 is operated to raise the piston rod 32 provided therein, thereby causing the valve body 2 to be displaced toward a position facing the passage 10 while being accurately positioned by the guide rod 60 acting as the vertical guide mechanism 6. Then, the control valves 56 and 57 are manipulated to achieve the supply of air so that a pneumatic pressure inside the first pneumatic supply line 54 is transmitted to the bellows 40, bellows units 40a or air bag 42 acting as the pressure applying mechanism 4 through the supply passage 53 of the pneumatic connector 52 and the supply passage 51 of the pneumatic transmission block 50.

As a result, in a state wherein the pneumatic transmission block 50 of the pneumatic transmission mechanism 5 is fixed in its original position, the bellows 40, bellows units 40a or air bag 42 expands to advance the valve body 2 while causing the valve body 2 to slide onto the upper portion of the horizontal guide plate 70 acting as the horizontal guide mechanism 7, so as to be accurately positioned.

At this time, the O-ring 20 previously installed at the tip end of the valve body 2 pressurizes the outer periphery of the passage 10 corresponding to the inner periphery of the valve housing 1 to seal it. In this way, as the passage 10 is closed with the valve body 2, the closing operation of the vacuum gate valve is completed.

During the vertical reciprocating movements of the valve body 2, the vertical guide mechanism 6 enables the accurate vertical positioning of the valve body 2, but this accurate vertical positioning is also possible without the vertical guide mechanism 6. In the same manner, during the horizontal reciprocating movements of the valve body 2, the horizontal guide mechanism 7 enables the accurate horizontal positioning of the valve body 2. Furthermore, at the same time as the transmission of the pneumatic pressure by the pneumatic transmission mechanism 5, the bellows 40, bellows units 40a or air bag 42 is operated to transmit the pneumatic pressure to the rear side of the valve body 2. By virtue of the structural feature of the bellows 40, bellows units 40a or air bag 42, the transmitted pneumatic pressure can be uniformly distributed to the whole portion of the valve body 2 and consequently to the O-ring 20 installed at the tip end of the valve body 2.

That is, the O-ring 20 is affected by the uniform and constant pneumatic pressure at

the whole portion thereof, thereby achieving the perfect air-tightness of the valve housing 1.

When it is desired to open the vacuum gate valve by returning the valve body 2 to its original position, first the control valves 56 and 57 are manipulated to open the first pneumatic supply line 54. According to the opening of the pneumatic supply line 54, the pneumatic pressure applied to the bellows 40, bellows units 40a or air bag 42 is removed, thereby causing the bellows 40, bellows units 40a or air bag 42 to move backward by its own elasticity along the horizontal guide plate 70 acting as the horizontal guide mechanism 7.

In the case that the elastic returning member 90 is installed, the valve body 2 is forcibly returned to its original position according to the returning operation of the elastic returning member 90 in a state wherein the pneumatic pressure is removed. On the other hand, as the bellows 40, bellows units 40a or air bag 42 acting as the pressure applying mechanism 4 communicates with the vacuum line 59 according to the direction change operation of the control valve 57, the bellows 40, bellows units 40a or air bag 42 acting as the pressure applying mechanism 4 is affected by the negative vacuum pressure generated by the vacuum pump 92, thereby causing the valve body 2 to forcibly perform its opening operation according to the constriction of the pressure applying mechanism 4.

After that, as the pneumatic cylinder 30 acting as the lifting mechanism 3 is operated to lower the piston rod 32 in a state wherein the valve body 2 moves backward as stated above, the pressure applying mechanism 4, pneumatic transmission mechanism 5 and the valve body 2 are lowered to their original positions along the guide rod 60 acting as the vertical guide mechanism 6, thereby being positioned at a ready position for next operation. In this way, the opening operation of the valve body 2 is completed.

During the opening and closing operation of the valve body 2 in relation to the passage 10 formed at the valve housing 1, the air-tightness between the fixed portion, such as the valve housing 1, and the movable portion, such as the piston rod 32 or guide rod 60, can be more perfectly maintained by installing the air-tightness retaining member 8 inside the valve housing 1.

Industrial Applicability

As apparent from the above description, a vacuum gate valve in accordance with the present invention is constructed differently from existing vacuum gate valves, that is, constructed in such a fashion that a pressure applying mechanism 4 of a valve body 2 comprises a bellows 40, a plurality of bellows units 40a or an air bag 42 operatively connected to the valve body 2. This connection between the valve body 2 and pressure applying mechanism 4 enables the valve body 2 to more uniformly and perfectly close a passage 10 formed at the valve housing 1, thereby improving the air-tightness effect between the valve body 2 and passage 10. Further, according to the present invention, a lifting mechanism 3 for raising or lowering the valve body 2 and the pressure applying mechanism 4 for pressurizing the valve body 2 can be more accurately guided by a horizontal guide mechanism 7 or vertical guide mechanism 6, which are constructed differently from existing guide mechanisms, thereby enabling the more accurate operation of the valve and improving the reliability of operation thereof. In addition, it is possible to prevent the generation of noise during operation by removing noise generating factors in advance.

Although the preferred embodiments of the present invention have been disclosed for illustrative purposes, those skilled in the art will appreciate that various modifications, additions and substitutions are possible, without departing from the scope and spirit of the invention as disclosed in the accompanying claims.