Fluid pump

Abstract: It is an object of the present invention to provide a fluid suction and discharge device capable of continuously discharging fluid with a predetermined flow rate and pressure continuously sucking the fluid without substantially giving rise to pulsation. The invention comprises an inner tube (1) rotatably fitted in a fitting hole of the device body, a cylinder (5) slidably fitted into the inner tube (1), and a plurality of through-holes formed in the inner tube (1), wherein when the cylinder (5) is reciprocated in association with rotation of the inner tube (1), and when one of the through-holes of the inner tube (1) is communicated with a suction hole of the device body, the other through-hole of the inner tube is communicated with a discharge hole of the device body, and when fluid is sucked from a communication suction hole thus communicated, fluid is discharged from the discharge hole thus communicated.

Description: This invention relates to a suction-discharge device for fluids according to the preamble of claim 1. Such a suction-discharge device for fluids that can be used as a multiple purpose pump as well as a compressor, and more specifically, the invention relates to a suction-discharge device for fluids using a rotary valve capable of continuously sucking and discharging fluids without occurrence of pulsations. In the past, in the vacuum pump which exhausts and reduces in pressure in the device, during the reciprocation of a piston, when pushing, pressure buildups while when pulling, pressure does not buildup, thus resulting in a drawback in which pulsations are violently generated. Further, in a conventional high pressure pump used as a boiler feed water pump or the like, a piston is used for a pump (a plunger pump), thus likewise resulting in a drawback in which outlet pressure buildups pulsations. Because of such pulsations as described, a pointer of a pressure gauge for measuring outlet pressure oscillates up and down, and therefore, presently, a damage preventive means is mounted on the pressure gauge. A suction-discharge device for fluids according to the preamble of claim 1 is disclosed in DE-1-348247. It is an object of this invention to provide a suction-discharge device for fluids capable of, without substantially bringing about pulsations, sucking continuously and discharging continuously under fixed flow rate and pressure. It is a further object of this invention to provide a suction-discharge device for fluids in which a fluid quantity to be sucked and discharged is made to be fixed. It is another object of this invention to provide a suction-discharge device for fluids capable of eliminating leakage of fluids almost completely. The aforementioned objects are achieved by the characterizing features of the present invention. More specifically. In short, the above-mentioned invention has found out that the cause for the effect that if a normal slot is formed, a quantity of fluid to be sucked and discharged indicates a sine curve results from the fact that an opening of a suction port and a discharged port communicated indicates a sine curve, and provides the subject matter that the suction hole and the discharge hole communicated are made to be the fixed size always to thereby eliminate pulsations substantially. Preferably, the through-holes of the inner tube, and the suction hole and the discharge hole of the device body may be formed so that the suction hole and the discharge hole communicated are moved in a moving direction of the cylinder. Preferably, the plurality of through-holes of the inner tube, and the suction hole and the discharge hole of the device body in contact with the through-hole have the same shape and same size, and are inclined from 30° to 60°, particularly, approximately 45°. Preferably, a plurality of sets, each set of which comprises a suction hole and a discharge hole of the device body, are formed, and the set of a suction hole and a discharge hole may be communicated with the same through-hole of the inner tube and inclined in the same direction. Preferably, with respect to the set of a suction hole and a discharge hole of the device body, the other is positioned at a position rotated by 180° of the inner tube from one. Preferably, the cylinder is reciprocated in association with the rotation of the inner tube. The device body will suffice to have a fitting hole, and is not particularly limited, but generally, a block body having an outer tube or a fitting hole is used. Preferably, the through-holes of the inner tube are formed to be inclined in the same direction to surfaces opposite to each other (the other is positioned at a position rotated by 180° of the inner tube from one) and both lengthwise sides at a position apart in the sliding direction of the cylinder. Preferably, the circumferential length of the through-holes/slots of the inner tube, and the suction hole and the discharge hole of the device body are formed to be an arched slot of approximately 90°. The above and other objects and advantages of the invention will become more apparent from the following description and the attached drawings. FIG. 1 is a sectional view showing one embodiment of the present invention. FIG. 2 is an exploded sectional view (partly a sectional view) showing one embodiment of the present invention. FIG. 3 is a sectional view for explaining the movement of a piston according to the present invention. FIG. 4 is a diagram showing a suction hole and a discharge hole communicated of the device according to the present invention, and a waveform of fluids sucked and discharged. FIG. 5 is a diagram showing a waveform of a quantity of fluids sucked and discharged by fluids in a case where a through-hole is formed in an inner tube. The embodiments of the present invention will be described hereinafter with reference to the drawings. FIG. 1 shows an embodiment of the present invention. A packing portion (a gland packing) 2 is connected at the rear of an inner tube 1 , and is fitted rotatably in an outer tube 4 through a bearing 3. It is noted that the inner tube 1 and the packing portion 2 are formed integrally of metal or an alloy. A cylinder (a piston body) 5 is fitted slidably in the inner tube 1, and a piston shaft 6 connected to the cylinder 5 is fitted rotatably in a fitting hole of the packing portion 2 of the inner tube 1. Arched (90°) through-holes (slots) 7 and 8 which are long in a rotational direction and inclined are formed, as shown in FIG. 2, on both sides of the inner tube 1. Both the through-holes (slots) 7 and 8 have the same shape and the same size and are formed adjacent to or in proximity of both side walls 9 and 9' of the inner tube 1, and positioned parallel with each other on surfaces (parts rotated by 180°) opposite to each other and parts apart in the sliding direction of the piston. Both the through-holes 7 and 8 are inclined by approximately 45°, and the circumferential length L is formed into an approximately 90° arched slot. The inclining direction may be either left or right in the rotational direction, and may be in the direction reversed to suction holes (discharge holes) 11, 11' of the device body. The device body is formed with the suction holes (discharge holes) 11, 11' which have the same shape and the same size as the inclined through-holes 7, 8 and are inclined in the direction reversed to the through-holes 7, 8 and capable of being crossed with both the through-holes 7, 8. FIG. 2 shows the suction holes (or discharge holes) 11, 11'. At the superposed positions of the back are formed the discharge holes (or suction holes) 11, 11' which have the same shape and the same size and are inclined in the same direction. Thus, each of the two numerals 11, 11' each designate one suction and one discharge hole. An outer tube 4 is formed to be a square, which is held by a manipulator 30 to constitute the device body. The outer tube 4 may be separated from the manipulator 30 as described, or it is of course that they may be integrated. The suction holes 11, 11' and the discharge holes of the outer tube 4 are formed at the position in contact with the fitting hole in which the inner tube 1 is fitted, the suction holes 11, 11' are communicated with suction ports a, c , and the discharge holes 11, 11' are communicated with discharge ports b, d . It is noted of course that the shape of the outer tube 4 may be cylindrical or other shapes. Being constituted as described above, when one of the through-holes 7 and 8 is communicated with the discharge port b (or d ) of the lower outer tube 4, the other is communicated with the suction port c (or a ) of the upper outer tube 4. Both the through-holes 7 and 8 have the same shape and the same size and are arranged in parallel, and the respective through-holes are symmetrical with respect to the central line lengthwise. When the cylinder 5 is reciprocated in association with the rotation of the inner tube 1, and the one through-hole 7 (or 8 ) is communicated with the one suction hole a (or c ) of the outer tube 4, 4a , the other through-hole 8 (or 7 ) is communicated with the discharge hole d (or b ) of the outer tube 4, 4a and when the fluid is sucked from the one communication hole, the fluid is discharged from the other communication hole. It is noted in the above-described embodiment that the suction holes and the discharge holes of the outer tube 4, 4a are formed in number of two ( a and c, b and d ), respectively. This is because of the reason that when one of the through-holes 7, 8 of the inner tube 1 is communicated with the suction hole a (or c ) of the outer tube, the other through-hole 7 (or 8 ) of the inner tube 1 is communicated with the discharge hole b (or d ) of the outer tube. It is noted that the suction holes ( a and c ) and the discharge holes ( b and d ) may be communicated with each other, respectively. The start position shown in FIG. 3 (A) is a position (a rotary valve angle 0°) in which the piston is pressed to the extreme end in this figure. The suction holes a, c and the discharge holes b, d are closed. The figure shows that the suction hole a is in a state of the suction start, and the discharge hole d is in a state of the discharge start. When the inner tube 1 is rotated by 90°, the piston assumes a position moved back half, as shown in FIG. 3 (B). Being the position from FIG. 3 (A) to FIG. 3 (B), the back through-hole 8 gradually rotates from 0° to 90° of rotational angle to assume a state of capacity 0 (left end of FIG. 4) to capacity 10 (center of FIG. 4). This state shows that fluids are discharged fixed by fixed amount. Fluids are sucked fixed by fixed amount from the surface through-hole 7. In FIG. 4, the black slot is a slot 11 of the outer tube, and the white portion is an opening (a communicated suction hole (or a discharge hole)) crossed with the through-hole/slot 7 (or 8 ) of the inner tube 1 and formed. When the inner tube 1 is further rotated by 90° (180° rotated position), there assumes a position in which the piston shown in FIG. 3 (C) is pulled to the rear end, which is a momentarily switching position of the suction port-discharge port. The suction holes a, c and the discharge holes b, d are closed, in which the suction hole c is in a state of the suction start, and the discharge hole b is in a state of the discharge start. Being the position from FIG. 3 (B) to FIG. 3 (C), the back through-hole 8 gradually rotates from 90° to 180° to assume a state of capacity 10 of FIG. 4 (center of FIG. 4) to capacity 0 (right end). This state shows that fluids are discharged fixed by fixed amount. When the inner tube 1 is further rotated by 90° (270° rotated position), the piston assumes a position advanced half, as shown in FIG. 3 (D). Being the position from FIG. 3 (C) to FIG. 3 (D), the back through-hole 8 assumes a state of capacity 0 of FIG. 4 (right end) to capacity 10 (center of FIG. 4). This state shows that fluids are sucked fixed by fixed amount from the back through-hole 8. Fluids are discharged by fixed by fixed amount from the surface through-hole 7 . When the inner tube ( 1 ) is further rotated by 90° (360° rotated position), the position is returned to the initial start position as shown in FIG. 3 (E). That is, this position is a position in which the piston is pushed to the extreme end, which is a momentarily switching position of the suction port-discharge port. In this state, the suction holes a, c and the discharge holes b, d are closed, in which the suction hole a is in a state of the suction start, and the discharge hole d is in a state of the discharge start. Being the position from FIG. 3 (D) to FIG. 3 (E), the back through-hole 8 assumes a state of capacity 10 of FIG. 4 (center of FIG. 4) to capacity 0 (left end). This state shows that fluids are sucked fixed by fixed amount from the back through-hole 8 . FIG. 4 shows a waveform of a quantity of fluids that is sucked and discharged from the suction holes a, c and the discharge holes b, d . Since the sizes of the suction holes and discharge holes communicated (portions indicated by white in FIG. 4) are the same always when suction and discharge take place, as described above, an output waveform of one cycle is always constant even if a rotational angle changes, and a continuous operation waveform is also constant as shown in FIG. 4. This waveform indicates that no pulsations occurs. It is noted that the longitudinal line X of the continuous waveform is a waveform line that occurs momentarily when the rotational angle of the crankshaft is switched from 360° to 1°. Suppose that 1 cycle is 0.5 second, a switching position is about (1/500) x 2 second, which is therefore substantially the same that a fixed quantity of fluids is sucked and discharged. It has been confirmed from experiments that pulsations are not brought about substantially. While in the above-described embodiment, a description has been made of that the cylinder 5 comes in contact with both side walls 9, 9', it is to be noted that the cylinder does not come in contact with both side walls but may be reciprocated at an apart position. A heat resistant and wear resistant oil seal 12 is fitted and mounted in the outer circumference of the cylinder 5 . Accordingly, the cylinder may be reciprocated at high speeds under high temperature. A piston shaft 6' is connected to the extreme end of the cylinder 5, and the piston shaft 6' is slidably fitted in a fitting hole 14 of a side wall projecting portion (a device cover) 13 of the inner tube 1. The device cover 13 is secured to the outer tube 4 by means of screws. The device cover 13 is in contact with the inner tube 1 through an 0-ring 15 . Since the piston shaft 6' is connected to the extreme end of the cylinder 5 as described above, the volume of the chamber formed by contact of the cylinder 5 with the forward and backward side walls 9, 9' is the same whereby a fixed quantity of fluids can be sucked and a fixed quantity of fluids can be discharged always, thus enabling complete elimination of pulsations. It is noted that the piston shaft 6' may be constituted so that it is fitted into the cylinder 5 against the force of spring. The piston shaft 6 is held slidably by the gland seal 16 of the gland packing 2, a ring-like passage is formed in the outer circumference of the gland seal 16, a passage 18 in communication with the suction holes a, c of the device body is provided through the ring-like passage and a passage 17, and the ring-like passage, the passage 17 and the passage 18 constitute a bypass passage. The suction hole a and the suction hole c are communicated with each other through the passage 19. A communication portion of the passage 18 with the passage 17 is formed to be ring-like. The rear end of the gland packing 2 and the rear end of the outer tube 4 are placed in contact rotatably through a fluorine seal packing 20, and the seal packing 20 is pressed and held by a packing flange 21. The gland seal 16 is encased in the gland packing 2, and similarly pressed and held by a packing flange 21' . A first gear (a tubular bevel gear) 22 is connected to the end of the inner tube 1, and the first gear 22 is engaged at right angle with a second gear (a bevel gear) 24 secured to a rotational shaft 23 of the motor. A crankshaft 25 for reciprocating the cylinder (piston body) 5 through the piston shaft 6 is secured to a rotational body 26 secured to the rotational shaft 23 of the motor. Since the first gear 22 and the second gear 24 are the same in number of teeth, when the inner tube 1 rotates once, the piston shaft 6 reciprocates once. The crankshaft 25 is secured to the rotational body 26, the cylinder 5 is reciprocated by the rotation of the rotational body 26, and when the rotational body 26 rotates once, the crankshaft 25 and the piston shaft 6 reciprocate once, and the inner tube 1 rotates once. The crankshaft 25 may be rotated together with the second gear 24, and therefore, a gear meshed with the second gear 24 may be provided, and it may be secured to the gear provided. A fixed position of the crankshaft 25 is varied between the center of the rotational body 26 and the outer circumference by means of a stroke adjusting screw 27 whereby the distance for which the piston is reciprocated can be varied to vary the suction and discharge quantities of fluids. It is noted that the suction and discharge quantities can be varied even by varying the rotational speed of the motor. Pressure and or flow rate of fluids discharged from the through-hole communicated is detected, and the rotational speed of the inner tube 1 and the reciprocating speed of the cylinder 5 are controlled on the basis of a signal detected. One of the pressure and the flow rate of fluids may be detected and controlled, but preferably, both of them are detected to control pressure and flow rate of fluids discharged constant. According to above-described embodiment, since the sizes of openings of the suction hole and the discharge hole communicated are nearly the same, a fixed quantity of fluid can be sucked and a fixed quantity of fluid can be discharged always to enable almost complete elimination of pulsations. Further, if design is made so that the volume of the chamber formed by a completely pushed position and a completely pulled position of the cylinder is the same, it is possible to discharge the same quantity of fluids as the suction quantity positively, thus enabling complete elimination of pulsations. Further, if a bypass passage is provided which communicates with the suction hole of the device body directly or through a seal material from a contact portion between the piston shaft of the cylinder and the rotational body, leakage of hydrogen can be eliminated, and therefore, it can be used as a hydrogen pump for supplying fuel to a fuel cell. In the past, the leakage of hydrogen could not been eliminated, and a hydrogen pump has not been developed. Therefore, the accomplishment of development of a hydrogen pump is an extremely epochal invention. While in the above-described embodiment, the through-holes 7, 8 are formed into an arched shape which is long in a rotational direction and inclined, it is noted that the through-holes 7, 8 need not be always formed as described above, but mere arched (preferably 90°) through-holes will suffice. In this case, the suction holes and the discharge holes of the device body may be also mere openings. However, in the aforementioned suction-discharge device, when an inner valve rotates from 0° to 180°, the size of an opening becomes large gradually till 90°, and thereafter becomes small gradually, as shown in FIG. 5, and therefore, an outlet waveform is a crown sine curve as shown in FIG. 5, thus posing a problem that pulsations are brought about. It is noted that if two devices are used, and rotated with 90° deviated, it is possible to always suck a fixed quantity and discharge a fixed quantity, thus enabling prevention of pulsations. In the device according to the present invention, a check valve is not used for a pump mechanism, and a piston type is employed, because of which the suction can be performed positively, and the same quantity as the suction quantity can be discharged positively. Accordingly, the device is highly accurate without bringing about pulsations and without loss of energy. Furthermore, the discharge pressure is high because the principle for mechanically pushing by way of a piston acts, thus enabling use it as a compressor also. Roles of a vacuum pump and a compressor can be performed by a single device, which function was achieved first by the device of the present invention. In the device according to the present invention, fluids can be discharged quickly or slowly by varying the rotational frequency, and pressure as well as flow rate of fluids discharged can be made constant. The device according to the present invention can be utilized as a vacuum pump, a high pressure pump, a fixed quantity feed pump or a compressor. The device that can be utilized for the multiple purpose as described has not at all been accomplished heretofore. According to the present invention, since the sizes of opening of the suction hole and the discharge hole communicated can be made almost the same, a fixed quantity of fluids can be sucked and a fixed quantity of fluids can be discharged always, thus enabling almost completely elimination of pulsations.

Claims: A suction-discharge device for fluids, comprising an inner tube (1) rotatably fitted in a fitting hole of the device body, a cylinder (5) slidably fitted into the inner tube (1), and a plurality of through-holes (7, 8) formed in the inner tube (1), wherein when the cylinder (5) is reciprocated in association with rotation of the inner tube (1), and when one of the through-holes (7, 8) of the inner tube (1) is communicated with a suction hole (11, 11') of the device body, the other through-hole (7, 8) of the inner tube (1) is communicated with a discharge hole (11, 11') of the device body, and when fluid is sucked from a communication suction hole (11, 11') thus communicated, fluid is discharged from the discharge hole (11, 11') thus communicated, characterized in that the through-holes (7, 8) of said inner tube (1) each being a slot which is long in a rotational direction and inclined, the suction hole (11, 11') and the discharge hole (11, 11') of said device body being formed into a through-hole to be crossed with said through-holes (7, 8). The device according to claim 1, wherein the throughholes (7, 8) of the inner tube (1), and the suction hole (11, 11') and the discharge hole (11, 11') of the device body are formed so that the suction hole (11, 11') and the discharge hole (11, 11') communicated are moved in a moving direction of the cylinder (5). The device according to claim 2, wherein said through-holes (7, 8), and the suction hole (11, 11') and the discharge hole (11, 11') of said device body have the same shape and same size, and are inclined from 30° to 60° in the rotational direction. The device according to claim 3, wherein a plurality of sets, each set of which comprises a suction hole (11, 11') and a discharge hole (11, 11') of the device body, are formed, and the set of a suction hole (11, 11') and a discharge hole (11, 11') are communicated with the same through-hole (7, 8) of the inner tube (1) and inclined in the same direction. The device according to claim 1 or 4, wherein in each set of suction and corresponding discharge holes (11, 11') of the device body the suction hole is positioned opposite to the corresponding discharge hole with respect to the rotational axis. The device according to claim 1, wherein said cylinder (5) is reciprocated in association with the rotation of said inner tube (1). The device according to claim 1, wherein said device body is an outer tube (4) or a block body (30) having a fitting hole. The device according to claim 5, wherein the through-holes (7, 8) of said inner tube (1) are formed to be inclined in the same direction to surfaces opposite to each other and both lengthwise sides at a position apart in the sliding direction of the cylinder (5). The device according to claim 8, wherein the circumferential length of the through-holes (7, 8) of said inner tube (1), and the suction hole (11, 11') and the discharge hole (11, 11') of said device body are formed to be an arched slot of approximately 90°. The device according to claim 1, comprising a bypass passage (18) in communication with a suction port of a said device body from said inner tube (1) in contact with a piston shaft (6) of said cylinder (5) directly or through a seal material (16). The device according to claim 1, wherein a volume of a chamber formed by contact of said cylinder (5) with both walls (9, 9') is made to be fixed to make a quantity of fluids sucked and discharge fixed. The device according to claim 11, wherein the piston shaft (6) of said cylinder (5) is formed to be projected from said cylinder (5), and a projected part (6) of said piston shaft is supported slidably on the side wall (13) of the device body to thereby make a quantity of fluids sucked and discharge fixed. The device according to claim 1, wherein pressure and/or flow rate of fluids discharged from said communicated through-hole is detected, and the rotational speed of said inner tube (1) and the reciprocating speed of said cylinder (5) are controlled on the basis of a detected signal so that the fluids of fixed pressure or flow rate can be sucked and discharged. The device according to claim 1, wherein the end of said inner tube (1) is connected to or formed in a first gear (22), said first gear (22) is meshed with a second gear (24) that is rotated by a motor, a crankshaft (25) for reciprocating the piston shaft (6) of said cylinder (5) is secured to a rotary body (26) that rotates with a rotational shaft (23) of said motor, and when said inner tube (1) rotates once, said piston shaft (6) is reciprocated once.

Inventors: IKUTA KAZUMASA, IKUTA, KAZUMASA
Applicants: IKUTA KAZUMASA, IKUTA, KAZUMASA
Application year: 2001
Main classification: F04B7
IPC codes: F04B7, F04B35