Pump start up control

Abstract

The rotary vane vacuum pump comprises: an inlet for connection to the vacuum chamber and an outlet for exhausting fluid pumped by the vacuum pump; a rotor and a motor for driving the rotor. The pump has a venting channel for venting one of the pumping chambers within the vacuum pump. The venting channel has a flow control device for controlling flow through the venting channel. The flow control device is configured to allow flow through the venting channel at start up of the pump and to impede flow through the venting channel in response to at least one of: a predetermined time elapsing, a speed of rotation of the rotor reaching a predetermined threshold value, a motor current reaching a predetermined value and an output from a sensor, the output from the sensor being indicative of operation of the vacuum pump.

1 . A rotary vane vacuum pump for evacuating gas from a vacuum chamber, said rotary vane vacuum pump comprising:
 an inlet for connection to said vacuum chamber and an outlet for exhausting fluid pumped by said vacuum pump;   a rotor comprising a plurality of vanes and a stator, said rotor being configured for rotation within said stator, said rotor and stator defining a plurality of pumping chambers for pumping a fluid from said inlet to said outlet on rotation of said rotor;   a motor for driving said rotor; and   a venting channel for venting one of said plurality of pumping chambers within said vacuum pump, said venting channel comprising a flow control device for controlling flow through said venting channel;   said flow control device being configured to allow flow through said venting channel at start up of said pump and to impede flow through said venting channel in response to at least one of: a predetermined time elapsing, a speed of rotation of said rotor reaching a predetermined threshold value, a motor current reaching a predetermined value and an output from at least one sensor, said output from said at least one sensor being indicative of operation of said vacuum pump.   
     
     
         2 . A vacuum pump according to  claim 1 , wherein said rotary vane vacuum pump further comprises said at least one sensor, said at least one sensor comprising at least one of a temperature sensor, a pressure sensor, a humidity sensor, and a sensor for sensing a number of rotations of said rotor. 
     
     
         3 . A rotary vane vacuum pump according to  claim 1 , wherein:
 said inlet comprises a movable closure element for opening or closing said inlet, said movable closure element being configured to move between an open and a closed position in response to a pressure on a vacuum pump side of said movable closure element rising above a pressure on a vacuum chamber side of said movable closure element; wherein   said venting channel is in fluid communication with said vacuum chamber side of said movable element, such that said fluid control device allowing flow through said venting channel causes said movable element to move to said closed position.   
     
     
         4 . A rotary vane vacuum pump according to  claim 1 , wherein said venting channel is configured to open into the rotary vane pump closer to said inlet to said vacuum pump than to said outlet. 
     
     
         5 . A rotary vane vacuum pump according to  claim 1 , wherein said venting channel vents to a pressure above atmospheric pressure. 
     
     
         6 . A rotary vane vacuum pump according to  claim 1 , wherein said rotary vane vacuum pump comprises a lubricant sealed sliding vane vacuum pump and said venting channel vents to a lubricant casing of said pump. 
     
     
         7 . A rotary vane vacuum pump according to  claim 1 , wherein said flow control device is configured to open said venting channel or close said venting channel. 
     
     
         8 . A rotary vane vacuum pump according to  claim 1 , wherein said flow control device is configured to control a degree of opening and thus, a flow through said venting channel. 
     
     
         9 . A rotary vane vacuum pump according to  claim 1 , wherein said flow control device comprises a valve. 
     
     
         10 . A rotary vane vacuum pump according to  claim 9 , wherein said valve comprises a mechanical valve comprising a resilient member for biasing said closure element towards said closed position. 
     
     
         11 . A rotary vane vacuum pump according to  claim 9 , wherein said valve comprises an electrically controlled valve configured to operate in response to control signals sent by control circuitry. 
     
     
         12 . A rotary vane vacuum pump according to  claim 1 , said rotary vane pump further comprising control circuitry configured to:
 control said motor for driving said vacuum pump; and   to control said flow control device;   said control circuitry being configured to control said flow control device to be allow flow through said venting channel at start up of said pump, to control said motor to start driving said pump and then to control said flow control device to impede flow through said venting channel in response to at least one of: a predetermined time elapsing, a speed of rotation of said rotor reaching a predetermined threshold value, a motor current reaching a predetermined value and an output from said at least one sensor, said output from said at least one sensor being indicative of operation of said vacuum pump.   
     
     
         13 . A method of starting a rotary vane vacuum pump according to  claim 1 , said method comprising:
 controlling a flow control device to allow flow through a venting channel;   starting rotation of the rotor of the pump; and   in response to at least one of a predetermined time elapsing, a speed of rotation of said rotor reaching a predetermined threshold value, a motor current reaching a predetermined value and an output from a sensor, said output from said sensor being indicative of operation of said vacuum pump, impeding flow though said venting channel.   
     
     
         14 . A method according to  claim 13 , said method further comprising:
 causing a movable element to move from obscuring an inlet to said vacuum pump to open said inlet to said vacuum pump by said step of impeding flow through said venting channel.   
     
     
         15 . A method according to  claim 13 , wherein said step of impeding flow through said venting channel comprises closing a valve.