Degasifying liquid pump

Abstract: A gas removable pump for liquid comprising a housing having an inlet for introducing the liquid thereinto and an outlet for feeding the liquid therefrom, a drive shaft extending into the housing and having formed therein an axial bore, a rotary pump disposed within the housing, and a discharging chambor defined within the housing and separated from the rotary pump in a liquid-tight manner. The rotary pump includes a rotor secured to the drive shaft for co-rotation therewith and a plurality of cells for feeding the liquid, each cell constituting a separator for gas-rich liquid upon rotation of the rotor. A stationary shait extends in the axial bore between the rotary pump and the discharging chamber. A connecting arrangement is provided in the drive shaft and stationary shaft for selectively connecting each cell with the discharging chamber. Also provided is an ejector for ejecting into the discharging chamber the gas-rich liquid separated in the cells through the connecting arrangement. The gas-rich liquid gathers at inner portions of the cells due to a centrifugal force and is discharged by mesns of the ejector through the connecting arrangement.

Description: The present invention generally relates to a pump for feeding a liquid and, more particularly, to a pump having a gas removal function for removing gaseous contaminants contained in the liquid to thereby feed the liquid containing little gaseous contaminants. In various fields of industry, a requirement exists to remove gaseous contaminants contained in a liquid which are fed by a pump. One example can be found in a chemical industry where raw materials, intermediate products or final products in the form of liquid are fed by the pump to be processed and/or stored. These liquid materials and products often contain gaseous contaminants which cause problems during feeding, processing and at the final products and should therefore be removed. Also, various lubricating oils tend to contain gaseous contaminants during use, examples thereof including oils for use in engine, gear, automatic transmission, torque converter, power steering, hydraulic actuator, turbine, compressor, quenching, rolling, metal working and traction device. Such gaseous contaminants adversely affect the lubrication and hydraulic properties and are desired to be removed. There has been a known technique which utilizes a buoyancy of gases for removing the contaminants from the liquid. Another approach has resulted in a use of centrifugal force generated by a vortex flow of the liquid as disclosed in, for example, Japanese Patent Publication JP-A-44-23803 and 61-36444 and Japanese Patent Laid-Open JP-A-1-104315. Due to a difference in density, the gas-rich liquid having a smaller specific gravity gathers in an area around a center of the vortex flow and the liquid containing little gaseous contaminants is separated to gather in a peripheral area. However, such known gas removal devices are provided separately from a pump for feeding the liquid, and do not suggest an integration of the pump and gas removal device. To install the pump and gas removal device in different portions of feed pipes of a chemical plant or lubricating system necessarily involves not only an increased work but also an increased space for the assembly and is therefore undesirable. This is particularly important when only a limited space is available for installation, such as in an automobile engine and an automatic transmission where miniaturization is one of the essential requirements in a design. FR-A-2564744 discloses a degasifying method and apparatus employing a centrifugal pump. Liquid is extracted from the suction side of the pump blades and conducted to a stilling zone through a hollow drive shaft of the impeller. The degasified liquid is returned upstream of the pump. Accordingly, an object of the invention is to provide an integrated degasifying pump which can efficiently separate gaseous contaminants from a liquid to be pumped, without a need of additional energy other than required for rotating the pump. Another object of the invention is to provide a degasifying pump for liquid which may easily be installed in a relatively small space. According to the present invention, there is provided a degasifying liquid pump comprising: a housing having an inlet for introducing a liquid containing gaseous contaminants thereinto and an outlet for feeding the degasified liquid therefrom; a drive shaft extending into said housing and having formed therein an axial bore; a rotary pumping means disposed within said housing between said inlet and said outlet for feeding the liquid, said rotary pumping means including a rotor secured to said drive shaft for co-rotation therewith, a plurality of vanes extending outward from said rotor and acting to separate the liquid containing gaseous contaminants passing through the rotary pumping means into a gas-rich liquid and a gas-poor liquid by centrifugal force upon rotation of said drive shaft; a discharging chamber for receiving said gas-rich liquid, located within said housing and separated from said rotary pumping means by a partition; ejecting means for ejecting said gas-rich liquid into said discharging chamber, said ejecting means comprising an outer end of a radial bore formed in a larger diametered portion of said drive shaft; and conduit means for passage of said gas-rich liquid from said rotary pumping means to said ejecting means, the diameter of the larger diametered portion of said drive shaft being greater than the diameter of a portion of the rotary pumping means defining the inlet sections of said conduit means for receiving said gas-rich liquid from said rotary pumping means; characterised in that: the plurality of vanes extending outward from said rotor define a plurality of separator cells, each cell comprising a part of said inlet sections of said conduit means and being formed to be successively in fluid connection with the inlet for introducing the liquid containing gaseous contaminants and with the outlet for the degasified liquid; in that said degasifying liquid pump further comprises a stationary shaft extending in said axial bore between said rotary pumping means and said discharging chamber; and in that said conduit means are formed both in said drive shaft and said stationary shaft and selectively provide for fluid connection of each said separator cell with said discharging chamber through said ejecting means. In a preferred embodiment of the invention, the conduit means includes a removal passage formed in the stationary shaft to extend along the axis thereof and a radial passage extending from each cell to the inner surface of the drive shaft defining the axial bore. A first groove may extend between the removal passage and the peripheral surface of the stationary shaft and have an opening at the peripheral surface for communication with the radial passage, the opening having a certain width in the circumferential direction. Other objects, features and advantages of the present invention will be apparent from the following description of the preferred embodiments thereof when taken in conjunction with the accompanying drawings. Fig. 1 is a longitudinally sectioned schematic view illustrating a degasifying pump for liquid according to an embodiment of the invention; and Fig. 2 is a cross sectional view taken along line II-II of Fig. 1. Referring to Fig. 1 of the drawings, a degasifying pump for liquid according to a preferred embodiment of the present invention has a generally cylindrical housing 10 having opposite open ends, one of the ends, i.e. the left-hand end in Fig. 1, being sealingly closed by a disk-shaped cover 12. A cap 14 rests on the axially outer surface of cover 12, and these cap and cover are fixed to the housing 10 by bolts 16. Fastened to the right-hand end of the housing by bolts 18 is a head cover 20 which defines a discharge opening for a rotary pump 22 as described below. A drive shaft 24 extends into the housing 10 along the axis thereof through the cap 14 and cover 12 and terminates at the end of head cover 20. The cap 14 and head cover 20 have recesses within which are received bearings 26 for supporting the shaft 24. A suitable seal 28 is provided around the shaft 24 at the outer end of cover 14. The rotary pumping means 22 (hereinafter "rotary pump 22") which comprises a vane pump in the illustrated embodiment, is disposed in the housing 10 adjacent the right-hand end thereof. Specifically, the rotary pump comprises a rotor 30 coaxially attached to the shaft 24 for co-rotation therewith and a casing 32 secured to the inner surface of the housing in such a manner that the casing is eccentric relative to the shaft 24, as in the conventional rotary pump. An inlet 34 is defined between a projection 36 and a partition wall 38 of the housing 10 to introduce a liquid such as an oil thereinto. A wall 40 extends radially inward at a position corresponding to the projection 36 for defining an intake opening 42 of the rotary pump 22. The partition wall 38 has an O-ring 44 fitted around the shaft 24 and defines in cooperation with the cover 12 a discharging chamber 46 which is sealingly separated from the inlet 34 and communicates with the outside of the housing 10 through a hole 48 having a valve 50. A drain hole 52 is formed is the wall of housing 10 at a position opposite to the hole 48 to connect the chamber 46 with a return passage 54 which extends to the inlet 34. A float valve 56 and a check valve 58 are provided in the return passage 54 as in an usual drainage system. The head cover 20 is formed with an outlet 60 extending between a discharge opening 62 of the pump 22 and an exit 64 in an end flange 66 which is secured to the head cover 20 by bolts 68. The drive shaft 24 has formed therein an axial bore 70 extending from the right-hand end of the shaft to the discharging chamber 46, in which is received a stationary shaft 72 that is integral with the end flange 66. Formed along an axis of the stationary shaft 72 is a removal passage 74 to connect a first groove 76 with an expanded end portion 78 of passage 74 where a check valve 80 adapted to normally close the removal passage 74 is accommodated. Portion 78 is closed by a plug 82. A second groove 84 is formed radially outward of the end portion 78 along the entire circumference of the stationary shaft 72 to communicate the portion 78 with radial bores 86 in a flange 88 which is formed by enlarging a part of the drive shaft 24. Thus, the second groove 84 and radial bores 86 always communicate with each other. The flange 88 has a diameter greater than that of an annular body 90 of the rotor 30. A circumferential projection 89 is formed on the outer surface of the stationary shaft 72 and extends to a position closely adjacent the inner surface of drive shaft 24 for providing a substantially liquid-tight seal between the second groove 84 and the radial bores 86. As shown in FIG. 2, the rotor 30 comprises the annular body 90 which is secured together to form an integral unit with the shaft 24 and a plurality of vanes 92 which are slidably received in radial holes 94 formed in the annular body 90 and shaft 24. The vanes 92 are urged radially outward by elastic means (not shown) in the holes 94 so that the outer ends thereof are always in contact with the inner surface of casing 32 to thereby define cells 96a to 96h which vary their volume as the annular body 90 rotates. It is to be noted that these structures are well known in the art. Formed in the annular body 90 are a number of orifices 98 each of which opens into the cell 96. In the illustrated example, five orifices 98 axially spaced from each other open into each cell 96 and are combined together to form a common passage 100 which extends through the body 90 and shaft 24 to the inner surface of the latter where an opening 102 of first groove 76 in the stationary shaft 72 approximates. The opening 102 is defined in a projection 104 similar to the projection 89 and extends in a circumferential direction by a predetermined angle, i.e. about 90 degrees in the illustrated example. Accordingly, the common passage 100 for each cell 96 communicates with the opening 102 only during a certain phase of rotation of the shaft 24 and rotor 30. In FIG. 2 the common passages for the cells 96d and 96e are aligned or communicate with the opening 102, the cell 96d being at the end of intake phase while the cell 96e is at the beginning of compression phase. It is generally preferable to set the position and circumferential width of the opening 102 in such a manner that it corresponds to either the intake or compression phase or both of these phases of the cells. The orifices 98 in each cell are positioned adjacent the vane 92 of forward side in the rotational direction. Two small passages 106 are formed through the drive shaft 24 to connect the axial bore 70 with the outlet 60 and the discharging chamber 46, respectively. Another small passage 108 is provided in the projection 104 at the opposite side of the groove 76. All these passages are provided for the purpose of lubrication which is particularly necessary at the projections 89 and 104 in order to ensure smooth rotation of the shaft 24 relative to the stationary shaft 72. The drive shaft 24 is a two-part structure and is assembled together at a spline 110 after the pump 22 and flange 88 are received within the housing 10 from the opposite open ends thereof. When the shaft 24 is rotated by an external drive source (not shown) to rotate the rotor 30, the liquid such as an oil containing gaseous contaminants flows from the inlet 34 into the cells 96 of the pump 22. The liquid in the rotating cell 96 is subjected to a centrifugal force, whereby the liquid containing gaseous contaminants, i.e. gas-rich liquid, having small density is separated and gathers near the outer surface of annular body 90. More particularly, the gas-rich liquid tends to gather in a portion adjacent the vane 92 of forward side in the rotating direction. The rotational movement of drive shaft 24 also creates a centrifugal force at the outer open ends of radial bores 86 so that a suction force is generated in the removal passage 74 to open the check valve 80. This suction force prevails over a similar force acting in the cell 96 because of the difference in diameters of the flange 88 and the annular body 90. Accordingly, the gas-rich liquid around the annular body in each cell is sucked into the orifices 98 to be ejected in the discharging chamber 46 via the removal passage 74 and the radial bores 86 when the common passage 100 communicates with the opening 102. In FIG. 2, the gas-rich liquid in the cells 96d and 96e are being discharged. The gases are finally discharged outside of the housing 10 through the hole 48, while the liquid component in the ejected material collects on the bottom wall of the chamber 46 for drainage via the drain hole 52 to flow back into the inlet 34. On the other hand, the liquid containing little gaseous contaminants is forced out of the housing 10 via the discharge opening 62 by a delivery pressure of the pump 22, the liquid being fed through the outlet 60 and the exit 64. As is described above, a pump according to the invention enables efficient removal of gaseous contaminants from the liquid to be pumped and therefore avoids the need for providing a gas removing device separate from the pump. Consequently, it is possible to minimize installation space for the pump. This is very valuable for miniaturizing an entire device, such as an automobile engine, in connection with which the present pump could be used. The assembly work of such an entire device would also be minimized because of the integrated structure of the present pump. It is an important feature in this respect that the gas removal function is achieved by using the rotational movement of drive shaft of the rotary pump, and no additional energy is thus required.

Claims: A degasifying liquid pump comprising: a housing (10) having an inlet (34) for introducing a liquid containing gaseous contaminants thereinto and an outlet (60) for feeding the degasified liquid therefrom; a drive shaft (24) extending into said housing (10) and having formed therein an axial bore (70); a rotary pumping means (22) disposed within said housing between said inlet (34) and said outlet (60) for feeding the liquid, said rotary pumping means including a rotor (30) secured to said drive shaft (24) for co-rotation therewith, a plurality of vanes (92) extending outward from said rotor (30) and acting to separate the liquid containing gaseous contaminants passing through the rotary pumping means into a gas-rich liquid and a gas-poor liquid by centrifugal force upon rotation of said drive shaft (24); a discharging chamber (46) for receiving said gas-rich liquid, located within said housing (10) and separated from said rotary pumping means (22) by a partition (38); ejecting means for ejecting said gas-rich liquid into said discharging chamber (46), said ejecting means comprising an outer end of a radial bore (86) formed in a larger diametered portion (88) of said drive shaft; and conduit means (98,100,76,74) for passage of said gas-rich liquid from said rotary pumping means (22) to said ejecting means (86), the diameter of the larger diametered portion (88) of said drive shaft being greater than the diameter of a portion of the rotary pumping means defining the inlet sections (98) of said conduit means for receiving said gas-rich liquid from said rotary pumping means (22); characterised in that: the plurality of vanes (92) extending outward from said rotor (30) define a plurality of separator cells (96), each cell comprising a part of said inlet sections of said conduit means and being formed to be successively in fluid connection with the inlet (34) for introducing the liquid containing gaseous contaminants and with the outlet (60) for the degasified liquid; in that said degasifying liquid pump further comprises a stationary shaft (72) extending in said axial bore (70) between said rotary pumping means (22) and said discharging chamber (46); and in that said conduit means are formed both in said drive shaft (24: 100) and said stationary shaft (72: 76,74) and selectively provide for fluid connection of each said separator cell (96) with said discharging chamber (46) through said ejecting means (86). A degasifying liquid pump as claimed in claim 1, wherein said conduit means includes a removal passage (74) formed in said stationary shaft (72) to extend along the axis thereof and a radial passage (98,100) extending from each said cell means (96) to the inner surface of said drive shaft (24) defining said axial bore (70). A degasifying liquid pump as claimed in claim 2, wherein said conduit means further comprises a first groove (76) extending between said removal passage (74) and the peripheral surface of said stationary shaft (72), said groove (76) having an opening (102) at the peripheral surface for communication with said radial passage (100). A degasifying liquid pump as claimed in claim 3, wherein said opening (102) of said groove (76) has a position and a circumferential width such that said radial passage (100) communicates with said opening (102) when said separator cell means (96) is in an intake phase. A degasifying liquid pump as claimed in claim 3, wherein said opening (102) of said groove (76) has a position and a circumferential width in such a manner that said radial passage (100) communicates with said opening (102) when said separator cell means (96) is in a compression phase. A degasifying liquid pump as claimed in claim 3, wherein said opening of said groove has a position and a circumferential width in such a manner that said radial passage communicates with said opening when said separator cell means (96) is in intake and compression phases. A degasifying liquid pump as claimed in claim 3, wherein said conduit means further comprises the radial bore (86) formed through said drive shaft (24) and a second groove (84) in said stationary shaft (72) for communicating said removal passage (74) with said radial bore (86). A degasifying liquid pump as claimed in claim 7, wherein said second groove (84) is formed along the entire circumference of said stationary shaft (72). A degasifying liquid pump as claimed in claim 7, further comprising first and second circumferential projections (104,89) formed on said stationary shaft (72) having outer surfaces closely adjacent the inner surface of said drive shaft (24) to provide a substantially liquid-tight seal between said opening (102) of said first groove (76) and said radial passage (100) and between said second groove (84) and said radial bore (86) respectively. A degasifying liquid pump as claimed in claim 7, further comprising a check valve (80) disposed in said removal passage (74) for preventing a reverse flow of gas-rich liquid. A degasifying liquid pump as claimed in claim 2, wherein said rotary pumping means (22) further includes a casing (32) secured to the inner surface of said housing (10) eccentrically relative to said drive shaft (24). A degasifying liquid pump as claimed in claim 11, wherein said rotor (30) further comprises an annular body around said drive shaft (24) wherein the plurality of vanes are supported by said annular body and urged radially outward to be in contact at the outer ends thereof with the inner surface of said casing (32), each said separator cell means (96) being defined by said casing (32), said annular body and two said vanes (92) adjacent each other. A degasifying liquid pump as claimed in claim 12, wherein said radial passage (98) opens into said separator cell means (96) at a position adjacent the vane (92) leading the radial passage (96) in the direction of rotation. A degasifying liquid pump as claimed in claim 13, wherein said radial passage (98) comprises a plurality of axially spaced orifices (98) each having an opening to said cell (96) and a common passage (100) connecting said orifice (98) with the inner surface of said drive shaft (24). A degasifying liquid pump as claimed in claim 1, wherein said housing (10) includes fastened thereto a head cover (20) for defining a discharge opening of said rotary pumping means (22) and said outlet (60). A degasifying liquid pump as claimed in claim 15, wherein said stationary shaft (72) has an end flange (66) fixed to said head cover (20). A degasifying liquid pump as claimed in claim 1, wherein the wall of said housing (10) defining said discharging chamber (46) has formed therein a hole (48) for discharging the gases outside of said housing (10) and a drain hole (52) for drainage of liquid component . A degasifying liquid pump as claimed in claim 17, further comprising a return passage (54) connecting said drain hole (52) with said inlet (34) of said housing (10). A degasifying liquid pump as claimed in claim 18, further comprising a check valve (58) and a float valve (56) disposed in said return passage (54). A degasifying liquid pump as claimed in claim 1, wherein said drive shaft (24) comprises two sections joined together by a spline (110).

Inventors: KITADA AKIHARU, YABUMOTO JUNSUKE, YANO HISASHI, KITADA, AKIHARU, YABUMOTO, JUNSUKE, YANO, HISASHI
Applicants: MITSUBISHI OIL CO, MITSUBISHI OIL COMPANY, LIMITED
Application year: 1990
Main classification: B01D19
IPC codes: F04C2, F04D17, F04C15, B01D19