Hermetic vacuum pump isolation valve

Abstract

A vacuum pump isolation (VPI) valve is interposed between a vacuum pump and a vacuum chamber. During normal operation of the vacuum pump, the VPI valve is open, allowing fluid communication between the vacuum pump and the vacuum chamber. When the vacuum pump becomes non-operational such as by losing power, the VPI valve closes, thereby isolating the vacuum chamber from the vacuum pump. The closing of the VPI valve is driven by the exhaust gas pressure of the vacuum pump. The VPI valve becomes exposed to the exhaust gas pressure by the opening of a pilot valve, which may occur as a result of the vacuum pump ceasing to operate. By this configuration, the VPI valve is hermetic and does not require ambient air for its operation.

What is claimed is: 
     
         1 . A vacuum pump isolation (VPI) valve, comprising:
 a pump inlet housing enclosing an inlet interior;   a valve element disposed in the inlet interior, the valve element configured for switching between an open state of the VPI valve and a closed state of the VPI valve and configured for switching to the closed state in response to pressure, wherein at the open state the valve element allows fluid flow between a vacuum pump and a vacuum chamber via the inlet interior, and at the closed state the valve element blocks fluid flow between the vacuum pump and the vacuum chamber; and   a pilot valve configured for communicating with the inlet interior and an internal exhaust gas line of the vacuum pump, the pilot valve switchable between an open pilot valve position and a closed pilot valve position, wherein at the open pilot valve position the pilot valve allows exhaust gas from the internal exhaust gas line to apply a pressure to the valve element effective to switch the valve element to the closed state, and at the closed pilot valve position the pilot valve blocks exhaust gas flow from the internal exhaust gas line to the valve element.   
     
     
         2 . The VPI valve of  claim 1 , comprising a valve seat disposed in the inlet interior, wherein the valve element comprises a piston movable between an open piston position corresponding to the open state of the VPI valve and a closed piston position corresponding to the closed state of the VPI valve, and at the closed piston position the piston contacts the valve seat. 
     
     
         3 . The VPI valve of  claim 2 , comprising a control volume chamber disposed in the inlet interior and at least partially bounded by the piston, wherein movement of the piston varies a volume of the control volume chamber. 
     
     
         4 . The VPI valve of  claim 3 , comprising a flexible diaphragm attached to the pump inlet housing and the piston and at least partially bounding the control volume chamber, wherein the flexible diaphragm moves with movement of the piston. 
     
     
         5 . The VPI valve of  claim 3 , wherein the control volume chamber is enclosed such that the control volume chamber is at least partially fluidly isolated from the vacuum chamber. 
     
     
         6 . The VPI valve of  claim 3 , comprising an inlet port in communication between the inlet interior and the vacuum pump, and a conductance-limiting orifice in communication between the inlet port and the control volume chamber. 
     
     
         7 . The VPI valve of  claim 1 , comprising a flexible diaphragm disposed in the inlet interior and configured to at least partially fluidly isolate the pilot valve from a portion of the inlet interior communicating with the vacuum chamber. 
     
     
         8 . The VPI valve of  claim 1 , comprising a spring configured for biasing the valve element into switching to the open state. 
     
     
         9 . The VPI valve of  claim 1 , wherein the pilot valve is configured to be normally open and to switch to the closed pilot valve position in response to receiving power. 
     
     
         10 . A vacuum pump, comprising:
 the VPI valve according to  claim 1 ;   a pump body, wherein the internal exhaust gas line is disposed in the pump body;   a first exhaust gas transfer line providing fluid communication between the internal exhaust gas line and the pilot valve; and   a second exhaust gas transfer line providing fluid communication between the pilot valve and the control volume chamber.   
     
     
         11 . The vacuum pump of  claim 10 , wherein the pilot valve is configured to be held at the closed pilot valve state in response to receiving power, and further comprising a pumping element, a motor configured for driving movement of the pumping element, and a power source configured for supplying power to both the vacuum pump and the pilot valve and cutting off power to the pilot valve in response to the motor ceasing operation. 
     
     
         12 . The vacuum pump of  claim 10 , wherein the first exhaust gas transfer line and the second exhaust gas transfer line are fluidly isolated from an ambient environment outside the vacuum pump. 
     
     
         13 . The vacuum pump of  claim 10 , comprising a scroll pumping stage disposed in the pump body and communicating with the inlet interior and the internal exhaust gas line. 
     
     
         14 . A vacuum pump isolation (VPI) valve, comprising:
 a valve seat disposed in the inlet interior;   a piston disposed in the inlet interior, the piston movable between an open piston state and a closed piston state, wherein at the open piston state the piston allows fluid flow between a vacuum pump and a vacuum chamber via the inlet interior, and at the closed piston state the piston contacts the valve seat and blocks fluid flow between the vacuum pump and the vacuum chamber;   a control volume chamber disposed in the inlet interior and at least partially bounded by the piston, wherein movement of the piston varies a volume of the control volume chamber; and   a pilot valve configured for communicating with the control volume chamber and an internal exhaust gas line of the vacuum pump, the pilot valve switchable between an open pilot valve position and a closed pilot valve position, wherein at the open pilot valve position the pilot valve allows exhaust gas from the internal exhaust gas line to pressurize the control volume chamber to a pressure effective to move the piston to the closed piston state, and at the closed pilot valve position the pilot valve blocks exhaust gas flow from the internal exhaust gas line to the control volume chamber.   
     
     
         15 . A vacuum pump, comprising:
 the VPI valve according to  claim 14 ;   a pump body, wherein the internal exhaust gas line is disposed in the pump body;   a first exhaust gas transfer line providing fluid communication between the internal exhaust gas line and the pilot valve; and   a second exhaust gas transfer line providing fluid communication between the pilot valve and the inlet interior.   
     
     
         16 . A vacuum system, comprising:
 a vacuum pump comprising an internal exhaust gas line;   a vacuum chamber;   a vacuum isolation (VPI) valve switchable between an open VPI valve state and a closed VPI valve state, wherein at the open VPI valve state the VPI valve allows fluid flow between the vacuum pump and the vacuum chamber, and at the closed VPI valve state the VPI valve blocks fluid flow between the vacuum pump and the vacuum chamber; and   a pilot valve communicating with the internal exhaust gas line and the VPI valve, the pilot valve switchable between an open pilot valve state and a closed pilot valve state, wherein at the open pilot valve state the pilot valve allows exhaust gas to flow from the internal exhaust gas line to the VPI valve at a pressure effective to switch the VPI valve to the closed VPI valve state, and at the closed pilot valve state the pilot valve blocks exhaust gas flow from the internal exhaust gas line to the VPI valve.   
     
     
         17 . The vacuum system of  claim 16 , wherein the VPI valve comprises:
 a pump inlet housing enclosing an inlet interior;   a valve element disposed in the inlet interior, the valve element configured for switching between the open VPI valve state and the closed VPI valve state and configured for switching to the closed VPI valve state in response to pressure,   wherein at the open pilot valve state the pilot valve allows the exhaust gas from the internal exhaust gas line to apply a pressure to the valve element.   
     
     
         18 . The vacuum system of  claim 16 , wherein the VPI valve comprises:
 a pump inlet housing enclosing an inlet interior;   a valve seat disposed in the inlet interior;   a piston disposed in the inlet interior, the piston movable between a first position corresponding to the open VPI valve state and a second position corresponding to the closed VPI valve state, wherein at the first position the piston allows fluid flow between the vacuum pump and the vacuum chamber via the inlet interior, and at the second position the piston contacts the valve seat and blocks fluid flow between the vacuum pump and the vacuum chamber; and   a control volume chamber disposed in the inlet interior and at least partially bounded by the piston, wherein movement of the piston varies a volume of the control volume chamber,   wherein at the open pilot valve state the pilot valve allows the exhaust gas to pressurize the control volume chamber.   
     
     
         19 . The vacuum system of  claim 16 , comprising a first exhaust gas transfer line providing fluid communication between the internal exhaust gas line and the pilot valve, and a second exhaust gas transfer line providing fluid communication between the pilot valve and the VPI valve. 
     
     
         20 . The vacuum system of  claim 16 , wherein the vacuum pump is a backing pump, and further comprising a high-vacuum pump communicating with the vacuum chamber, and wherein:
 at the open VPI valve state the VPI valve allows fluid flow between the backing pump and the high-vacuum pump, and at the closed VPI valve state the VPI valve blocks fluid flow between the backing pump and the high-vacuum pump.