the various embodiments of the pump device have already been described above in general terms but these descriptions will now be supplemented with further description with reference to the drawings . fig1 a shows a longitudinal section , viewed obliquely , through the first embodiment of the device according to the invention for producing high pressure in a fluid . in the cylinder ( 1 ) is the hollow piston ( 2 ) with the coaxial bore ( 7 ) and the valve member ( 3 ) in the partly open position of the valve . between the bottom of the valve member ( 3 ) and the end of the cylinder is the high pressure chamber ( 4 ). the high pressure chamber is closed off by another component ( not shown ). mounted on the hollow piston , outside the cylinder , is a device ( not shown ) by means of which the hollow piston can be displaced inside the cylinder . fig1 b shows the hollow piston ( 2 ) viewed obliquely . the end of the hollow piston facing the valve member is provided with a groove ( 5 ) which is bounded , at its end facing the valve member , by a rectangular section annular land forming a step ( 8 ) the diameter of which is less than the external diameter of the hollow piston ( 2 ) and greater than the base diameter of the groove . the front edge at the end of the hollow piston may be chamfered . fig1 c shows the valve member ( 3 ) viewed obliquely . it has , for example , three channels ( 9 ) on its outer surface to facilitate fluid flow when the valve is open . mounted on the valve member ( 3 ), on its side facing the hollow piston , are , for example , three snap hooks ( 6 ) the width of which , in the direction of the circumference of the valve member , is less than a third of this circumference . the snap hooks ( 6 ) are shorter in the axial direction than the length of the , for example , grooved end of the hollow piston . during assembly , the valve member ( 3 ) is placed on the end of the hollow piston ( 2 ), and the hooks ( 10 ) slide into the groove . the hollow piston together with the valve member is then pushed into the cylinder . when the valve is open , the inner edge of the hooks ( 10 ) abut on the step ( 8 ). when the valve is closed , the base of the valve member ( 3 ) facing the hollow piston fits tightly on the end of the hollow piston ( 2 ) which acts as the defined sealing surface . in order to take in the fluid , the hollow piston is lifted partly out of the cylinder , whereupon the valve automatically opens . the fluid flows through the bore ( 7 ) in the hollow piston and past the valve member into the high pressure chamber ( 4 ). in order to expel the fluid , the hollow piston ( 2 ) is pushed into the cylinder ( 1 ), whereupon the valve closes automatically , virtually instantly , and high pressure is generated in the fluid . fig2 a shows the second embodiment of the device according to the invention for producing high pressure in a fluid as a longitudinal section viewed obliquely . in the cylinder ( 1 ) is the hollow piston ( 11 ) and the valve member ( 13 ) in the partly open position of the valve . fig2 b shows a longitudinal section through the hollow piston ( 11 ) with the shaped outlet end ( 12 ) of the hollow piston . a displacement body ( 26 ) may be fixedly located in the hollow piston . fig2 c shows the valve member ( 13 ) as a longitudinal section viewed obliquely . mounted on the valve member is a coaxial , undercut peg ( 14 ) the projecting end of which engages behind the shaped edge ( 12 ) of the hollow piston . the end ( 15 ) of the peg facing the hollow piston may be chamfered . the peg may have an indentation or bore ( 16 ) extending in the axial direction and possibly longitudinal slots extending upwards from the end ( 15 ) thus forming snap hooks so that the peg can be pushed into the shaped end of the hollow piston , thereby engaging behind the shaped edge . fig3 a shows the third embodiment of the device according to the invention for producing high pressure in a fluid in longitudinal section viewed obliquely . in the cylinder ( 1 ) is the hollow piston ( 17 ) and the valve member ( 18 ) in the closed position of the valve . fig3 b shows a longitudinal section viewed obliquely through the hollow piston ( 17 ) with the shaped end ( 19 ). at the outlet end of the hollow piston is the widened portion ( 20 ) in which the valve member ( 18 ) is guided and mounted in axially movable manner . the inlet end of the widened portion ( 20 ) is chamfered or flat . fig3 c shows the cylindrical valve member ( 18 ) in longitudinal section viewed obliquely . both ends of the valve member are planar and are located perpendicularly to the axis of the valve member . the valve member ( 18 ) contains , for example , four stepped channels or flats ( 21 ) on its outer surface to facilitate fluid flow past the shaped end ( 19 ), i . e . the inturned lip , when the valve is open , the ends of the channels ( 21 ) being radially inward of the lip . the edge of the valve member ( 18 ) which abuts on the inclined base of the hollow chamber ( 20 ) may be chamfered . the diameter of the valve member ( 18 ) is less than the diameter of the widened portion ( 20 ) so that the valve member ( 18 ) can move virtually without friction in the widened portion ( 20 ). for assembly , the valve member ( 18 ) is pushed into the widened portion ( 20 ) before the outlet end ( 19 ) of the hollow piston is shaped . fig4 a shows the fourth embodiment of the device according to the invention for producing high pressure in a fluid in longitudinal section viewed obliquely . in the cylinder ( 1 ) are the hollow piston ( 22 ) and the valve member ( 23 ) in the closed position of the valve . the diameter of the valve member is less than the inner diameter of the hollow piston . fig4 b shows a longitudinal section , viewed obliquely , through the hollow piston ( 22 ) with the shaped outlet end ( 24 ) forming an inturned lip and the encircling constriction ( 25 ). the thick - walled tube ( 26 ) acting as the displacement body may be pushed into the hollow piston ( 22 ) and secured therein . fig4 c shows the valve member ( 23 ) in oblique view . at the outlet end of the valve member is a radially extending indentation ( 27 ) in the form of a transverse slot to facilitate fluid flow when the valve is open . fig4 d shows an alternative to the fourth embodiment in longitudinal section , viewed obliquely . in the cylinder ( 1 ) is the hollow piston ( 28 ), optionally with the displacement body ( 26 ), with the valve in the closed position . the diameter of the valve member ( 29 ) is less than the internal diameter of the hollow piston . fig4 e shows a longitudinal section , viewed obliquely , through the hollow piston ( 28 ) with the shaped outlet end ( 24 ) and the encircling constriction ( 25 ). at least one indentation ( 30 ) in the form of a recess or notch is provided on the shaped outlet end ( 24 ) to facilitate fluid flow when the valve is open . instead of the indentation there may be a convexity . fig4 f shows the valve member ( 29 ) in oblique view . in this case , the valve member is a straight cylinder with no recesses . fig5 shows the fifth embodiment of the device according to the invention for producing high pressure in a fluid , in longitudinal section and viewed obliquely . in the cylinder ( 1 ) is the hollow piston ( 31 ) which contains the displacement body ( 32 ). mounted on the cylindrically widened inlet end ( 33 ) of the hollow piston is the closure member ( 34 ) with the depression ( 35 ) and bore ( 36 ). in the indentation is the guided , axially movable valve member ( 37 ) which may be provided at its outlet end with a slot ( 38 ) as recess . the embodiments of the device according to the invention for producing high pressure in a fluid shown in fig2 a to 5 work in the same way as has already been explained with reference to fig1 a . fig6 a shows a longitudinal section through the preferred atomiser described in detail above with the spring biased and fig6 b shows a longitudinal section through the atomiser with the spring released . the upper housing part ( 51 ) contains the pump housing ( 52 ) on the end of which is mounted the holder ( 53 ) for the atomiser nozzle . this holder is preferably as described in german patent application p19536303 . 3 - 51 of 4 oct . 1995 ( and a parallel pct application being filed simultaneously herewith in the joint names of boehringer ingelheim international gmbh and the inventors ) the entire contents of which are incorporated herein by reference . in the holder is the nozzle member ( 54 ) and a filter ( 55 ). the hollow piston ( 57 ) fixed in the cup - shaped drive flange ( 56 ) of the blocking mechanism ( 62 ) partly projects into the cylinder of the pump housing . at its end the hollow piston carries the valve member ( 58 ). the hollow piston is sealed off by the seal ( 59 ). inside the upper housing part is the annular abutment ( opposite annular ridge ( 60 ) on the flange ) on which the flange rests when the spring is released . on the axial end of the cup - shaped driven flange is the abutment ( 61 ) by which the driven flange is held when the spring is biased . after the biasing of the spring , the generally annular blocking member ( 62 ) moves between the abutment ( 61 ) and a support ( 63 ) in the upper housing part , either because of its own elasticity or ( when it is more rigid ) by virtue of an external spring ( not shown ). the actuating button ( 64 ) is connected to the blocking member and can either move it bodily or deform it so that it releases the abutment ( 61 ). the upper housing part terminates in the mouth piece ( 65 ) and is closed off by the protective cap ( 66 ) which can be fitted thereon . the spring housing ( 67 ) with compression spring ( 68 ) is rotatably mounted on the upper housing part by means of the snapping lug ( 69 ) and rotary bearing . the lower housing part ( 70 ) is pushed over the spring housing and rotates with it to operate the helical sawtooth cam drive ( not shown ) for cocking the atomiser ( moving it from the fig6 b position to the fig6 a condition ). inside the spring housing is the replaceable storage container ( 71 ) for the fluid ( 72 ) which is to be atomised . the storage container is fitted with a stopper ( 73 ) through which the hollow piston projects into the storage container and dips its end into the fluid . mounted in the outer surface of the spring housing is the spindle ( 74 ) for the mechanical counter . at the end of the spindle facing the upper housing part is the drive pinion ( 75 ). the slider ( 76 ) sits on the spindle . an example of a suitable container is taken from the disclosure of u . s . pat . no . 5 , 316 , 135 , and is shown in fig7 . as described in u . s . pat . no . 5 , 316 , 135 , the storage container has a collapsible inner portion 7 and a stable outer portion 5 . outer portion 5 is a dimensionally stable outer container . inner portion 7 is an easily deformable inner bag . a more complete description of the container shown in fig7 may be found in u . s . pat . no . 5 , 316 , 135 . the embodiments shown in the drawings may be varied further . the components may be used together in a manner other than that shown in the drawings . the valve area of a medicinal atomiser according to fig1 a consists of a cylinder made of polybutylene - terephthalate with an internal diameter of 1 . 6 mm and an external diameter of 5 mm . the high pressure chamber is closed off by a nozzle carrier plate . in this plate is a nozzle 20 μm in diameter and the nozzle channel is 2 mm long . a metal hollow piston with an external diameter of 1 . 59 mm and a bore 0 . 35 mm in diameter is pushed into the cylinder . the hollow piston can be pushed 50 mm into the cylinder and its - stroke is 12 mm long . the hollow piston has an encircling turned groove 4 mm wide with a base diameter of 0 . 75 mm . the groove is bounded by a 4 . 0 mm long step with a diameter 1 . 15 mm . the outer edge of the turned end of the hollow piston is chamfered . the valve member made of polybutyleneterephthalate consists of a 2 mm thick disk 1 . 59 mm in diameter and 3 snap hooks . three semi - cylindrical channels 0 . 4 mm in diameter are provided as recesses on the outer surface of the disk . the snap hooks project 6 mm from the disk and the inner edge of the hooks is 4 . 2 mm away from the disk . the valve member may thus be moved axially 0 . 2 mm relative to the hollow piston . the delivery volume is 23 . 4 mm 3 . the pressure in the fluid is about 32 mpa ( 320 bar ). this atomiser is used to atomise or nebulize liquid pharmaceuticals for medicinal aerosol therapy . the atomiser delivers the drug in the required dose on each actuation . the valve area of a cosmetic atomiser corresponding to fig3 a consists of a cylinder of polyetherether - ketone with an internal diameter of 2 . 5 mm and an outer diameter of 8 mm . the high pressure chamber is closed off by a nozzle carrier plate . in this plate is a nozzle 25 μm in diameter with a nozzle channel 2 mm long . a hollow piston . of reinforced plastics with an external diameter of 2 . 48 mm and a bore 0 . 5 mm in diameter is pushed into the cylinder . the hollow piston can be pushed 45 mm into the cylinder and its stroke is 24 mm . the hollow piston is drilled out to an internal diameter of 1 . 85 mm over a length of 5 . 0 mm at its outlet end . the base of the drilled - out chamber in the hollow piston is chamfered . the outlet end of the hollow piston is thermally deformed . the valve member is a cylinder of polypropylene which is 3 . 0 mm high and 1 . 6 mm in diameter . four stepped channels are provided as recesses in the outer surface . the valve member can be displaced axially about 0 . 5 mm inside the hollow piston . the delivery volume is about 116 mm 3 . the pressure in the fluid is about 3 mpa ( 30 bar ).
a miniaturized device for pressurizing fluid . the device includes a hollow piston that provides a fluid path and a valve member . the valve member is configured for axial movement so that the valve axis remains parallel to the piston axis . the valve member is arranged at one end of the hollow piston . the valve member may be partially or completely disposed within the hollow piston . the device is particularly adapted for use in a mechanically operated atomizer to produce an inhalable aerosol of a liquid medicament without the use of propellant gas .