Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
  • F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
  • F04B53/00—Component parts, details or accessories not provided for in, or of interest apart from, groups F04B1/00 - F04B23/00 or F04B39/00 - F04B47/00
  • F04B53/06—Venting

Definitions

• the present invention relates to a rotary piston pump and especially, but not exclusively, to a high pressu re pump having a liquid discharge passage which is provided with a one-way valve.
• This one-way valve or non-return valve is adapted so as not to open the liquid discharge passage, until a very high pressure has been created within the pumping chamber defined by the piston within the pump cylinder.
• a high pressure piston pump has the disadvantage that it is not self-priming .
• a pressure which is sufficiently high to open the one-way valve in the discharge passage can normally not be obtained during the pressu re stroke, and during the succeeding suction stroke the compressed air will reexpand, which means that no liquid is sucked into the pumping chamber.
• high pressure piston pumps are used as homogenizing pumps for homogenizing milk samples in milk analyzing apparatuses , wherein the said one-way valve may function as a homogenizing valve.
• a homogenizing pump is for example disclosed in US patent No. 4,236,075.
• electrically controlled valves cause the fi rst part of each sample to be pumped to a waste container without counterpressure, whereby air is removed from the inlet passage and the pumping chamber. Thereafter a remaining part of the liquid sample is pumped through the homo ⁇ genizing valve under high pressu re.
• US patent No. 3,936,244 discloses a fuel pumping apparatus for supplying fuel to the cylinders of an internal combustion engine.
• the discharge passage of this pumping apparatus is formed within a rotary distributor member 11 which is driven by the associated engine, and which is adapted to communicate the discharge passage with a venting passage du ring the pressure strokes of the piston .
• This venting passage contains a spring loaded valve member and is normally closed by a threaded plug, which must be unscrewed when the pump is to be vented.
• the present invention provides a rotary piston pump which is self-priming even when it is operated at high pressures .
• the pump according to the present invention is of the type comprising a cylinder, a piston movably arranged within the cylinder so as to define a pumping chamber therein, and driving means for reciprocating the piston through successive suction and pressure strokes during which liquid is sucked into the pumping chamber through an inlet passage and discharged therefrom th rough a discharge passage, respectively, and for simultaneaously rotating the piston so as to communicate the pumping chamber with the inlet passage during each suction stroke and disrupt that communication during each pressure stroke of the piston, and the pump according to the invention is characterized in that the driving means are adapted to move the piston in the cylinder so as to briefly establish communication between the pumping chamber and a venting passage during the last part of each pressure stroke of the piston.
• the venting passage is opened and closed by the rotary piston , which functions as a valve member, whereby a rather simple and reliably structure is obtained .
• the piston also functions as a valve member controlling the liquid inlet passage of the pump, and the piston must consequently be provided with suitable bores, passages, and/or channels for performing its valve functions .
• a longitudinally extending recess communicating with the pumping chamber may be defined in the peripheral surface of the piston, said driving means being adapted to briefly register the recess with the venting passage du ring the last part of its pressure stroke.
• the piston may have an additional recess or passage for communicating the liquid inlet passage with the cylinder chamber during the suction strokes of the piston . It is preferred, however, to use the same recess for controlling the venting passage as well as the liquid inlet passage.
• the recess in the piston may have a narrow or pointed end part, and the venting passage may open into the wall of the cylinder at such a location that the pointed end part of the recess is registered with the venting opening at its pointed end part. Because the pointed end part of the recess has a very small peripheral width, the time period in which communication is established between the pumping chamber and the venting passage will be very short as desired, and the venting passage is closed, before the succeeding suction stroke is initiated so that sucking of air into the pumping chamber th rough the venting passage is avoided.
• the rotary piston pump according to the invention may be used for any suitable pu rpose. However, in the presently preferred embodiment it is used as a homogenizing pump in connection with
• the one-way valve in the discharge passage of the pump is in the form of a homogenizing valve.
• the homogenizing valve may then comprise a valve seat, a ball- shaped valve member, and an annular elastic sealing ring, for example an O-ring, biasing the valve member against the valve seat.
• an annular elastic sealing ring for example an O-ring, biasing the valve member against the valve seat.
• the annular sealing ring or O-ring functions to seal against the valve member, whereby the dead space of the homogenizing valve may be substantially re ⁇ cuted, whereby a smaller amount of liquid is required for purging or flushing the homogenizing valve when shifting from one milk sample to another.
• the use of an annular sealing ring as described allows for use of smaller liquid samples.
• the inner diameter of the annular sealing ring is substantially equal to the bore diameter or opening diameter of the valve seat, because transmission of possible vibrations of the valve member in one of the homogenizing valves to the valve member of a succeeding valve may then be prevented.
• Fig . 1 shows a side view and partially sectional view of an embodiment of the rotary piston pump according to the invention
• Figs. 2 - 5 illustrate the operation of the pump, each of the figures showing diagrammatically a side view and partially sectional view, and a cross-sectional view of the pump cylinder and the piston arranged therein,
• Fig. 6 shows a side view and partially sectional view of the rotary piston pump shown in Figs . 1 and 2 and of associated homogenizing valves, and
• Fig. 7 shows a sectional view along the line VI I -VI I in Fig . 6.
• the high pressure piston pump shown in the drawings is a homo ⁇ genizing pump which may, for example, be used in connection with a milk analyzing apparatus of the type disclosed in US patent No. 4,236,075.
• the pump comprises a pump cylinder 10, which is connected to a homogenizing valve unit 11 , and which contains a piston 12.
• the piston is connected to a piston rod 14 via a so- called "Olham-coupling" 13.
• the piston rod 14 is rotatably and axially displaceably arranged in bearing bushings 15 and 16, which are mounted in a bore 17 formed in a stationary frame part or apparatus part 18, see Fig . 1 .
• a sealing ring 14a sealing sur ⁇ rounding the piston rod 14 is mounted at the left (Figs 1 ) end of the bore 17.
• a driving mechanism for driving the piston 12 comprises a drum-like frame part 19 which is rotatably mounted on the stationary frame part 18 by means of a ball-bearing 20, and the drum-like frame part 19 comprises a toothed rim 21 which may be connected to a driving motor (not shown) by means of a toothed belt.
• a driving part 22 is screw-fastened to the right end of the rotatable frame part 19 and closed by means of a cover 24.
• a so-called joint bearing 24 is mounted within the driving member 22, and a shaft 25 is rotatably and displaceably mounted within the lining 24 ' of the bearing 24, and the end part of the shaft 25 extending from the bearing 24 is fixedly received in the bore of a sieeve-iike head 26 formed at the adjacent end of the piston rod 15.
• the pump cylinder 10 is fixed to the stationary frame part 18 by means of an intermediate part 28 provided with openings 27 and by means of a mounting block 29.
• the intermediate part 28 sur ⁇ rounds the coupling 13, and the mounting block 29 is provided with a piston gasket 30 and radially extending drainage tubes 31 .
• the homogenizing valve unit 11 in principle functions as a one-way valve or a non-return valve, which normally closes the liquid discharge passage 32 of the pump cylinder 10.
• the pump cylinder is also provided with a liquid inlet passage 33 and a venting passage 34.
• the piston 12 is provided with a milled recess 35 extending axially from the piston 12. This recess is shaped so that the piston may serve as a valve member controlling the liquid inlet passage 33 and the venting passage 34, when the piston perform its normal movements within the pumping cylinder, as will be explained more in detail below with reference to Figs . 2 - 5.
• Fig. 2 shows the pump during a pressure stroke of the piston 12.
• the piston 12 is in such a rotational position that the recess 35 is facing away from the liquid inlet passage 33 and the venting passage 34, and, consequently, the communication between these passages and the pumping chamber 35 defined by the piston in the cylinder is interrupted. Therefore further movement of the piston 12 against its inner position or top position causes compression of the medium contained in the pumping chamber 36. If the pumping chamber 36 is completely filled with liquid, the pressure w ithin the chamber 36 very quickly reaches a level at which the homogenizing valve or one-way valve 11 is opened, so that liquid under the high pressu re may be pressed from the pumping chamber 36, th rough the liquid discharge passage, and into the homogenizing valve unit.
• the end part of the recess 35 opposite to the piston 12 has a pointed shape, and the venting passage 34 is preferably positioned so that it will be uncovered by the pointed end 37 of the recess 35 when or immediately before the piston reaches its inner position or top position . This means that the venting passage 34 is closed again by the initial small rota ry movement of the piston 12 during the first part of the suction stroke.
• the venting passage 34 will be closed during almost all of the suction stroke while the liquid inlet passage 33 will be uncovered by the recess 35 in the piston . Consequently, the liquid inlet passage is communicating with the pumping chamber 36, whereby liquid is sucked into the pumping chamber through the liquid inlet passage 33 as illustrated in Fig . 4.
• the piston 12 When the piston 12 has reached its outer position or bottom position, it takes up such a rotational position that it closes the liquid inlet passage 33 as well as the venting passage 34, so that during the succeeding pressure stroke the medium present within the pumping chamber 36 may escape only through the one-way valve 11 -
• the pump according to the invention is self-priming. Liquid which might leak from the pumping chamber 36 past the piston 12 may be drained off through the draining tubes 31 .
• Figs . 6 and 7 show the homogenizing valve unit in detail.
• This homogenizing valve unit contains two homogenizing valves 38 and
• the homogenizing valve 38 has a valve seat
• a bail-shaped valve member 41 is pressed against the valve seat by means of a helical spring 42 which is arranged within a tubular spring housing 43 provided with external threads 43a and screwed into engagement with corresponding internal threads formed in a valve housing 44 common to two homogenizing valves.
• the outer end of the helical spring 42 is abutting a screw cover 45 which is screwed into the spring housing and by means of which the tension of the spring may be adjusted .
• the inner end of the spring is in -engagement with one end of a pressure transmitting pin 47 via a disc-shaped abutting member 46. The other end of the pin is in engagement with the ball-shaped valve member 41 .
• the pin 47 extends through a guiding sleeve 48, and the inner end of the sleeve 48 engages with an O- ring 49 which in turn is in engagement with the ball- shaped valve member 41 .
• the guiding sleeve 48 is maintained in the desired axial position by means of a locking ring 50, which is screwed into the spring housing 43 and is in engagement with the outer end of the guiding sleeve 48.
• the inner end portion of the guiding sleeve is received in a bore formed in a part 51 of the housing containing the valve member 41 .
• the part 51 as well as the valve seat 40 is maintained in position by the spring housing 43.
• the homogenizing valve 39 is of the same structure as the valve 38, and the parts of the valve 39 are indicated by the same reference numerals as the corresponding parts of the valve 38 but provided with ' .
• the valves 38 and 39 are interconnected by a connecting passage 52.
• a liquid outlet passage 53 is formed in the housing part 5V of the homogenizing valve 39. This outlet passage 53 leads to a conventional non- return valve 54 which is screwed into the common valve housing 44 and communicating with a dis ⁇ charge conduit 55.
• the housing parts 51 and 51 ' may be prevented from rotating in relation to the common housing 44 by means of pins 56 and 56' which are received in bores in the housing 44 so that their inner ends are extending into corresponding radial bores in the housing parts 51 and 51 " , respectively.
• the homogenizing valve 38 forming the first stage of the unit 11 may, for example, be adjusted so as to open the liquid discharge passage 32 of the pump at a pressure of about 120 atmospheres .
• the ball-shaped valve member 41 is lifted a small distance from its seat by overcoming partly the pressure of the helical spring 42 trans ⁇ mitted by the pin 47, and partly the pressu re exerted by the O- ring 49.
• This O-ring is preferably made from an elastic material having a certain inner friction, so that it is able to suppress vibrations which might be imparted to the ball-shaped valve member 41 . Fu rthermore, the O- ring serves as a sealing member
• the O-ring may, for example, be a standard O-ring marketed by the firm Mogens Christensen, Copenhagen , under the designation "R2007" .
• the liquid After having passed the homogenizing valve 38 the liquid continues through the connecting passage 52 to the homogenizing valve 39, which functions in the same manner as the homogenizing valve 38 apart from the fact that the valve 39 forming the second homo ⁇ genizing stage normally operates at a lower homogenizing pressure, for example in the order of 50 atmospheres.
• the homogenized liquid leaves the homogenizing valve 39 through the outlet passage 53, the non-return valve 54, and the discharge conduit 55.
• the high pressure piston pump described may be used in connection with homogenizing valve units of a type other than that shown, or for any other purpose, for which a self-priming high pressure piston pump is desirable.

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• Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Details Of Reciprocating Pumps (AREA)

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Family Applications (1)

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Citations (2)

• 1981
  • 1981-02-19 DK DK75181A patent/DK75181A/da unknown
• 1982
  • 1982-02-19 AU AU81445/82A patent/AU8144582A/en not_active Abandoned
  • 1982-02-19 WO PCT/DK1982/000016 patent/WO1982002928A1/en unknown
  • 1982-02-19 EP EP19820900631 patent/EP0072835A1/de not_active Withdrawn

Patent Citations (2)

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