Sensor for measuring hydraulic fluid pressure of a diaphragm compressor

Abstract

A pressure sensor having a housing connected to a compressor head, the housing including a piston movably mounted in a cylinder, the cylinder is fluidly connected to a high-pressure part of a hydraulic system of the compressor, where the piston is adapted to be moved in a first direction away from the compressor head by the pressure of the hydraulic fluid in the high-pressure part, thereby moving a displacement member which is movably attached to the housing by one or more flexible suspensions, and the piston is adapted to be moved in a second direction towards the compressor head by the flexible suspension via the displacement member.

1 . A pressure sensor comprising a housing connected to a compressor head, the housing comprising a piston movably mounted in a cylinder, the cylinder is fluidly connected to a high-pressure part of a hydraulic system of the compressor, wherein the piston is adapted to be moved in a first direction away from the compressor head by the pressure of the hydraulic fluid in the high-pressure part, the piston is thereby adapted to move a displacement member which is movably attached to the housing by one or more flexible suspensions, and wherein the piston is adapted to be moved in a second direction towards the compressor head by the flexible suspension via the displacement member. 
     
     
         2 . A pressure sensor according to  claim 1 , wherein the flexible suspensions are implemented as an array of bolts and springs. 
     
     
         3 . A pressure sensor according to  claim 1 , wherein the pressure sensor further comprise a displacement sensor adapted to detect the distance of the movement of the displacement member. 
     
     
         4 . A pressure sensor according to  claim 1 , wherein the displacement member and the piston is made of aluminium. 
     
     
         5 . A pressure sensor according to  claim 1 , wherein the center part of the displacement member which is in physical contact with the head of the piston is made of steel. 
     
     
         6 . A pressure sensor according to  claim 1 , wherein the shape of the head of the piston is spherical and wherein the contact point of the displacement member to the piston is concave. 
     
     
         7 . A pressure sensor according to  claim 1 , wherein the pressure sensor is connected to the hydraulic fluid distribution plate or the lower compressor head. 
     
     
         8 . A pressure sensor according to  claim 1 , wherein the cylinder end towards the displacement member is closed only leaving an opening through which the piston can obtain mechanical contact with the displacement member. 
     
     
         9 . A pressure sensor according to  claim 1 , wherein the array of flexible suspensions is fastening the displacement member to the housing so that movement of the displacement member requires a hydraulic fluid pressure above a displacement pressure. 
     
     
         10 . A pressure sensor according to  claim 1 , wherein the displacement sensor is a distance sensor. 
     
     
         11 . A pressure sensor according to  claim 1 , wherein the compressor is a diaphragm compressor compressing hydrogen gas to a pressure of at least 65 Mpa. 
     
     
         12 . A hydrogen fueling station comprising a first hydrogen storage and a second hydrogen storage and a compressor having an oblong shaped chamber moving hydrogen in a first pressure of the first hydrogen storage to a second pressure in the second hydrogen storage, wherein the compressor comprising a pressure sensor according to  claim 1 . 
     
     
         13 . A method of controlling the peak pressure of the high-pressure part of a hydraulic system of a diaphragm compressor pressurising a gas, the diaphragm compressor comprising:
 an injection assembly forming part of a hydraulic fluid path between a low-pressure part of the hydraulic system and the high-pressure part, the injection assembly comprising:
 an output valve, 
 a valve, and 
 an injection pump establishing a flow of hydraulic fluid from the low-pressure part to the high-pressure part when the output valve is open, and 
   a pressure sensor establishing a feedback signal representing the pressure in the high-pressure part,   wherein the injection pump establishing a pressure potential of injection of hydraulic fluid when the valve is closed and when the output valve is closed, and   wherein a controller is controlling the pressure potential of injection of hydraulic fluid into the high-pressure part, by control of the injection assembly based on the feedback signal and a hydraulic fluid peak pressure target value of a desired pressure of hydraulic fluid in the high-pressure part.   
     
     
         14 . A method according to  claim 13 , wherein the pressure potential of injection of hydraulic fluid is established in the injection assembly. 
     
     
         15 . A method according to  claim 13 , wherein the amount of hydraulic fluid injected into the high-pressure part in a compression cycle is determined by the established potential of injection of hydraulic fluid, wherein the potential of injection of hydraulic fluid is controlled by controlling the valve based on the pressure difference between the pressure represented by the feedback signal and the peak pressure target value. 
     
     
         16 . A method according to  claim 13 , wherein the pressure is increased during a plurality of compression cycles following the compression cycle during which the feedback signal representing the pressure of the high-pressure part was below the peak pressure target value. 
     
     
         17 . A method according to  claim 13 , wherein the feedback signal representing the pressure in the high-pressure part is measured in each compression cycle. 
     
     
         18 . A method according to  claim 13 , wherein the controller is controlling the potential of injection of hydraulic fluid so that the pressure in the high-pressure part is always above a reference potential which is equal to or higher than the inlet pressure of the gas. 
     
     
         19 . A method according to  claim 13 , wherein the feedback signal is established by a pressure sensor comprise a housing mounted to the high-pressure part in which a cylinder with a piston in fluidly connection with the hydraulic fluid of the high-pressure part is located, a displacement member and a displacement sensor, wherein the pressure of the hydraulic fluid in the high-pressure part is physically displacing a displacement member and wherein the size of the displacement is measured by a displacement sensor. 
     
     
         20 . A method according to  claim 1 , wherein the compressor is used for pressurizing hydrogen gas in a high-pressure storage of a hydrogen refueling station or of a fuel cell vehicle to a pressure above 35 Mpa.