Suction valve

A suction valve for a pipe line in which a medium flows is provided, whereby the flow can be closed and regulated and whereby back flow prevented. The suction valve includes a movable a closing mechanism (3) placed in a valve house (1), and an opposed counter face in the valve house. The closing mechanism (3) can be moved by the pressure of the medium flow by forming the closing mechanism (3) to be as piston parts or cylinder parts in a working cylinder. The pressure of the medium flow used for moving the closing mechanism (3) is led into the closing mechanism through an outlet valve (8,9,10), which outlet valve is fitted inside the closing mechanism (3).

FIELD OF THE INVENTION

The invention relates to a suction valve to be used in a pipe line intended for a flow medium, by which the flow can be closed, regulated and back flow prevented. The suction valve comprises a closing means including a movable closing part placed in a valve house, and for the closing part the closing means also includes a counter face in the valve house. The closing part can be moved by the pressure of the flow medium. Preferably the closing means is formed to be as piston parts or cylinder parts in a working cylinder. The valve is especially suited as a suction valve for screw and rotor compressors, since the suction valve causes only a small loss of flow, can be regulated, and closes as needed. By closing the suction valve, back flow from the compressor is prevented when the compressor stops.

BACKGROUND OF THE INVENTION

Previously known is, among others, a suction valve from U.S. Pat. No. 6,695,007, where the suction flow of the medium to the compressor keeps the valve open. When the flow reduces, or for instance, when the suction effect of the compressor lessens, the spring in the valve pulls the closing means against the seat surface and closes the valve. In such a spring-return valve, a little more suction pressure loss always builds up over time, but because of the suction flow, the valve-closing means is kept open. However, pressure loss builds up further, even if the spring would be, as to its counter force, quite weak. When rather big compressors are working almost day and night, so that there is a slight deterioration in the operating efficiency, and because of the noted suction valve with a weak spring, the suction valve becomes a large expense in the production of compressed air. In addition, it is difficult to regulate a suction valve returning by spring force into an intermediate position near the closing state in order to achieve the relief state of compressor. Thus, the deterioration occurs, the relief which must be done relative to closing of the valve, while the compressor is working, is either adding a spring back factor or otherwise moving the closing means with less force against the closing surface.

BRIEF SUMMARY OF THE INVENTION

In order to avoid the above presented disadvantages and to achieve by compressor use, as to its flow loss, a very small suction valve, a new suction valve intended for a medium flow is disclosed. This suction valve can be placed in a pipe line, and the closing means thereof, which can be moved by the pressure of the medium flow, is formed as a piston or a cylinder part in a working cylinder which operates by means of the pressure of the medium flow. The above presented invention is characterized in that the necessary pressure of the flow material is led into the closing means through an outlet valve fitted inside the closing means.

The advantage of the invention is that the keeping of the valve in the open position does not cause any flow loss by the valve. The valve remains open both due to its mass by force of gravity and by the compressor's suction pressure which pressure is allowed to impact in a cylinder space formed by closing means into a direction pulling the closing means into the open position. In operation, the compressor must only one time create the negative pressure led through the outlet valve into the cylinder space, and afterwards there is no loss in keeping the valve open. Control of the outlet valve fitted inside the closing means of the suction valve takes place with the pressure of the medium led to it. Closing and opening of the suction valve is controlled to take place by the pressurized available medium. Thus control takes place in spite of the compressor running. When the closing valve is as to its inlet opening installed upwards, the closing means facilitates by its own mass the opening of the suction valve. The closing means can also be regulated to any intermediate place between the close and open positions. The outlet valve motions from closed state to open state of the closing means can be made quite fast, since the pressure of the medium that presses the closing means to the closed position discharges fast through the outlet valve to the suction tube of the compressor. The suction valve causes very little pressure loss to the medium flow passing it, since it is possible to make the design of the incoming and exit sides very streamlined.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1shows a suction valve, the outer casing of which is formed of two joined housing parts1aand1b, which can be attached to each other with bolts through holes6as shown. Connected and fixed to housing part1b, by wing2led across the circular flow channel, is a fixed circular sleeve-like part4of a closing means for the suction valve. The outer surface of sleeve-like part4is fitted to work as a sliding surface together with a closing part3. Closing part3and sleeve-like part4are like a cylinder and a piston, and thus they move in relation to each other. Closing part3is furnished with a packing11, whereby when closing part3nestles in a closing position against the counter surface of housing part1aas shown inFIG. 2, packing11is compressing in this closing position. Wing2, which connects sleeve-like part4to housing part1b, and housing part1bis a little thicker in the connection area than in the remainder thereof, whereby it is possible to lead through housing part1bat the connection area a channel5from the outside into the sleeve-like part4.

An outlet valve is fixed inside sleeve-like part4by a threaded coupling. The outlet valve has a tap hole7, which leads directly to the suction space of the compressor. Furthermore, the outlet valve comprises, in a cylindrical frame8, a closing flange10which is made of a flexible material, such as polyurethane. To the frame8, a supporting flange9is connected. The closing flange10closes tap hole7, if the pressure behind the closing flange10, led along channel5and further along suction line13, is greater than the pressure in the tap hole7. The pressure of the tap hole7dominates also inside closing part3and sleeve-like part4in the cylinder space formed thereby. In the open state described in theFIG. 1, no pressure is led through the channel5to the outlet valve. For instance, channel5can also be joined to the same pressure with the compressor suction side, in other words to a chamber into which the tap hole7discharges. The closing means stays in the state shown byFIG. 1, and does not try get closed. Thus the flow losses caused by the closing means are minimized.

The closed situation ofFIG. 2can be reached both on compressor stopping and working. For instance, from the compressor's pressure side, control pressure is led behind the closing flange10of the outlet valve, whereby this compressor pressure moves to close the tap hole7. The flexible material of closing flange10gives in, so that pressure can get, by the way of the flexing outer edge of flange10, into the cylinder space to circulate inside the closing part3, and the pressure pushes the closing part3to closed position. Consequently, the compressor runs relieved or it is stopped. The pressure cannot get discharged backward off the compressor.

If it is desired to get the suction valve open, this happens very fast, since the control pressure of channel5which is led out is a very small amount of air. Then, in the cylinder space, the pressure from the inside of the closing part3is at once able to push closing flange10of the closing means a little away from the tap hole7, whereby the pressure from the inside of the closing part3quickly discharges through the tap hole7into the suction space of the starting compressor and the closing flange10remains in the open position shown byFIG. 1. Inside the closing part3, negative pressure sucked by the compressor arises, and the closing means move quickly to the open-position and the flow can pass through the suction valve. It will thus be appreciated that the running of the compressor or its starting accelerates the opening of the suction valve. Further, the opening of the suction valve is especially accelerated by the position of the suction valve, if it is according to theFIGS. 1 and 2, whereby the closing part3moves downward to open-position, assisted by the force of gravity.

It is also possible for the closing part3to be adjusted to intermediate positions. This is possible since the position of the quick outlet valve according toFIG. 2can be moved by leading through channel5only a regulated amount of medium into the space formed between the closing part3and the sleeve-like part4.

FIG. 3shows the main diagram of the valve connections. Valve14is a suction valve, comprising inFIGS. 1 and 2housing part1aand closing part3. Valve15is an outlet valve comprising inFIGS. 1 and 2parts8,9and10. Valve16is a control valve, by the opening of which the pressure is led to the outlet valve15and this causes that the suction valve14to close in spite of the running of compressor12. The control pressure runs through the outlet valve15into the closing means, and lifts up the closing flange10whereby the suction valve14closes. When the pressure control of the control valve16is removed, the low pressure or suction in the suction line13leading to the compressor removes pressure from the inside of the closing part3so that closing part3closes moves to the open position of the suction valve14shown inFIG. 1. The pressure line starting from compressor12has the reference number17. The inlet opening of the suction valve14is shown inFIG. 3opposite the outlet suction line13. From compressor12, pressure line17takes control pressure to the control valve16. It is also possible to take control pressure from some other outside pressure source.