Non-sliding vacuum gate valve
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a non-sliding vacuum gate valve, and, more particularly, to a novelly improved non-sliding vacuum gate valve which allows the occurrence of particles to be minimized. 
     2. Description of the Related Art 
     An example of a construction of a conventional non-sliding vacuum gate valve is disclosed by the present applicant in U.S. Pat. No. 5,002,255. 
     In the construction of this valve example, a valve rod is moved downward and a valve body is positioned on valve seats at the openings of a valve housing. Then this valve rod is tilted to push the valve body against the valve seats, thereby closing the opening of the valve box. 
     Conventional non-sliding vacuum gate valves, which have the above-described construction, have the following problems. 
     The valve is closed when the valve rod is longest. This results in larger valves because a large-diameter valve rod is used to maintain the strength thereof. 
     In addition, since the valve rod and the valve body are connected by springs in a freely operable manner, it is impossible to prevent particles from being produced during operation. This makes them unsuitable for use in a chamber of a semiconductor producing device, employed in a clean room which must be kept very clean. 
     Further, when the valve rod is tilted by air cylinders and arm members, it is impossible to prevent particles from being produced from the portion where pushing members and the arm members contact one another. 
     Still further, since it is extremely difficult to open the valve box in a sealed state after assembly, it is troublesome, for example, to exchange the O-rings of the valve body. 
     In the conventional construction, opening and closing operation speed are reduced because linear movement and tilting are performed in connection with each other. 
     SUMMARY OF THE INVENTION 
     In view of the above-described problems, the present invention aims at providing a non-sliding vacuum gate valve which particularly allows the occurrence of particles to be minimized. 
     According to the present invention, there is provided a non-sliding vacuum gate valve performing opening and closing operations on an opening on a valve box by a valve body which is connected to a valve rod, based on the movement and tilting of this rod, by means of a seal bellows, the seal bellows having one end provided on the valve box, the valve so constructed as comprising: a swing body or connecting member provided on and extending between each rod end of a plurality of cylinders, the cylinders being provided on the valve box; a cam body which has a cam hole and is provided on the connecting member; a cam follower which engages in the cam hole and is provided at the end portion of the valve rod; and a slide body which is provided at the other end of the seal bellows and connected to the cam body by means of springs; wherein linear movement of the cam body causes linear and tilting movements of the valve rod and valve body. 
     In addition, in more detail, a pair of guide bodies, each having a guide hole or slot, are each provided on the respective inner sides of the cylinders, and a guide roller, provided on the slide body, is engaged in the guide hole. 
     Further, in more detail, the cam hole has a linear guide section for linearly guiding the cam follower, and a lock section for locking the cam follower. 
     In the non-sliding gate valve of the present invention, each of the cylinders are operated to cause the valve rod and the valve body to move linearly upwards or downwards by means of each rod, slide body, and cam body, thereby allowing the valve to either open or close the opening of the valve box. 
     With the valve box being in an open or closed state, when the cylinders are further operated to cause the cam body to move linearly, the cam follower at the end portion of the valve rod moves along the linear guide section of the cam hole of the cam body, so that the valve body tilts. At the same time, the valve body tilts and contacts closely with the valve seat at the opening of the valve housing, and closes it. When the cam body, which is operated by the cylinders, is moved linearly, the cam follower engages with the lock section, which is a bent portion of the cam hole. The valve rod may remain tilted in a locked state, so that the valve opening remains closed, even after the driving state of the cylinder is released. 
     Further, the opening is opened by operating each of the cylinders in reverse mode and linearly moving the connecting member, cam body and the slide body in the opposite direction. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front view of a construction of a non-sliding vacuum gate valve of the present invention; 
     FIG. 2 is a cross sectional view of FIG. 1 taken along line A--A; 
     FIG. 3 is an operational structural view of the valve of FIG. 2 in a half-closed state; 
     FIG. 4 is an operational structural view of the valve of FIG. 2 in a fully closed state; 
     FIG. 5 is a cross sectional view of the valve of FIG. 1 in an open state; and 
     FIG. 6 is a structural view of a cam hole. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     A detailed description will hereunder be given regarding a preferred embodiment of a non-sliding vacuum gate valve of the present invention with reference to the drawings. 
     Referring to FIG. 1, reference numeral 1 denotes a valve box or housing having a well-known valve opening 1B. The valve box 1 is disposed between the chambers of a semiconductor producing apparatus (not shown), used in a clean room. 
     A plurality of air-type cylinders 2 and 3 are mounted on a bonnet flange 1a of the aforementioned valve box 1. A tubular swing body or connecting member 4 extends between and is fixed to an end portion of each of rods 2a and 3a of each of the cylinders 2 and 3, with a screw 5, respectively. 
     A cam body 7 having a cam hole 6, which is obliquely formed with respect to the axial lines of the cylinders 2 and 3, is mounted on an underside a surface 4a of the connecting member 4. A roller-type cam follower 10 is mounted on the upper end of a valve rod 9 and moves within the opening 7a provided by the inverted C-shape cam body 7. The valve rod 9 is connected to a valve body 8 in the valve housing 1. 
     An inverted C-shape slide body 12, is connected to the cam body 7 by means of a plurality of supporting members 11 such as springs or flexible members. The valve rod 9 passes through a through hole 12a of the slide body 12. The slide body 12 and the valve rod 9 are integrally connected tightly together. A flexible vacuum seal bellows 13 has one end 13a fixed onto the bonnet flange 1a of the valve box 1 and the other end 13b connected to the slide body 12 at its upper end within the opening 12b provided by the inverted C-shape of the slide body 12. Therefore, a through hole 1A of the valve body 1 is kept in a sealed state by the valve rod 9, the seal bellows 13 and the slide body 12, so that the valve box 1 is kept air-tight during the operation of the valve rod 9. 
     As shown in FIGS. 2 through 4, the cam hole or slot 6 has a linear guide section 6a, and a lock section 6b, which is formed continuously with the linear guide section 6a, for locking the cam follower 10. The valve rod 9 is constructed so that it is locked when the cam follower 10 engages with the lock section 6b. As shown in FIG. 5, a guide roller 52, provided at the outer side of the slide body 12, engages in a guide hole 50, provided in at a guide body 51 at the inner side of each of the cylinders 2 and 3. 
     Next, the operation of the valve will be described. 
     When the valve is open, as illustrated in FIGS. 1, 2 and 5 operating each of the cylinders 2 and 3 causes the valve rod 9 and the valve body 8 to move downwards by means of each of the rods 2a and 3a, the connecting member 4, the cam body 7, and the slide body 12, as shown in FIGS. 2 and 3. At the same time, the seal bellows 13 contracts, as shown in FIG. 3, and the valve body 8 is in a lower position, laterally adjacent to, but not closing the opening 1B. 
     Under the above-described condition, when the cylinders 2 and 3 are further operated to move the cam body 7 downwards, the cam follower 10, at the end of the valve rod 9, moves along the linear guide section 6a of the cam body 7. As a result, the valve rod 9 is tilted, and, at the same time, the valve body 8 is also tilted as permitted by the compression and lateral movement of flexible members 11 due to the camming action, as shown in FIG. 4, to be brought completely together with the valve seat 1Ba surrounding at the opening 1B. As a result the opening 1B is closed. 
     Further, operating the cylinders and linearly moving the cam body 7 causes the cam follower 10 to engage with the lock section 6b, which is a bent portion of the cam hole 6. The valve rod 9 remains in a tilted locking state. The opening is capable of being closed by tilting the valve rod 9 even after the driving of each of the cylinders 2 and 3 has been stopped. In addition, in opening the closed opening 1B, each of the cylinders 2 and 3 are operated in reverse mode, so that the connecting member 4, the cam body 7, and the slide body 12 each move linearly in the opposite direction. In the aforementioned operation, as shown in FIG. 6, when the valve body 8 functions to close the opening, 1B, O-rings 8a come into contact with the valve seat 1Ba by means of a first cam lead D1, and is closed by means of a second cam lead D2. When it functions to open the opening, adhesive forces of the O-rings 8a with respect to the valve seat 1Ba are resisted, with the second cam lead D2, so as to tear away the 8a therefrom. 
     The non-sliding vacuum gate valve of the present invention is so constructed as to provide the following advantages. Linear movement of the swing body, the cam body, and the slide body by the cylinders alone allows the valve rod to move in a linear and tilted manner by means of the cam follower which engages in the cam hole. Accordingly, the amount of particles is minimized, making it unnecessary to take special measures against dust, as it has been done conventionally, in using a super-clean room. This greatly reduces costs. In addition, since movement in a linear and tilted manner can be performed in one movement, opening and closing operations can be performed at a much higher speed as compared to conventional valves.