WO2005010367A1

WO2005010367A1 - Fluid pump and motor

Info

Publication number: WO2005010367A1
Application number: PCT/KR2004/001894
Authority: WO
Inventors: Kyung-Yul Hyun
Original assignee: Kyung-Yul Hyun
Priority date: 2003-07-29
Filing date: 2004-07-27
Publication date: 2005-02-03

Abstract

The fluid pump of the present invention comprises a cylindrical rotating chamber including first and second opposite wall surfaces and a third wall surface connecting the first and second wall surfaces, a rotor which rotates within the rotating chamber about a rotational axis passing through the centers of the first and second wall surfaces and includes a contact area slidably brought into contact with the third wall surface of the rotating chamber and a non-contact area spaced apart from the third wall surface, and a blocking wall which is slidably brought into close contact with the outer circumferential surface of the rotor and configured such that the blocking wall can be moved toward or away from the rotational axis, wherein the contact and non-contact areas are formed on an outer circumferential surface of the rotor which is formed around the rotational axis and faces the third wall surface, and a fluid suction port and a fluid discharge port are provided at opposite positions adjacent to the blocking wall in a state where the blocking wall is located between the suction and discharge ports.

Description

FLUID PUMP AND MOTOR

Technical field The present invention relates to a fluid pump and motor, and more particularly, to a rotary fluid pump and motor.

Background Art A fluid pump is a device that sucks a fluid such as a gas or liquid and discharges the sucked fluid to the outside through rotation of a rotational shaft thereof by a driving device. On the other hand, a fluid motor is a device that receives a fluid and discharges the received fluid to the outside to cause a rotational shaft to rotate. The fluid pump and the fluid motor are opposite each other in view of their operations but are generally the same as each other in view of their structures. That is, the structure becomes a fluid pump if it is designed to suck and discharge a fluid by means of the rotation of a rotational shaft, whereas the structure becomes a fluid motor if it is designed to rotate a rotational shaft by means of the introduction of a fluid. Fluid pumps or motors are generally classified into reciprocating and rotary types in view of their structures. The reciprocating pump or motor is a structure in which a piston linearly reciprocates and is coupled with a rotational shaft within a cylinder through interaction with a fluid. A rotary pump or motor includes a vane type with sliding vanes, a gear type with two gears engaged with each other, and the like. The vane pump or motor is driven by means of an eccentric rotor with extendable and retractable vanes. The gear pump or motor is driven in such a manner that the two rotating gears engaged with each other interact with the fluid. The vane or gear type corresponding to a rotary type is relatively simpler than the reciprocating type in view of their structure, and is generally used when the pressure of the working fluid is in a low or middle-pressure range. The reciprocating type is more complex than the rotary type in view of their structures, but it can be used when the pressure of the working fluid is in a high-pressure range. The vane type is widely used due to advantages in that it is relatively simple in view of its structure and can be easily manufactured into a variable discharge volume type. However, the vane should be configured such that it can come in and out of a rotor. Further, the vane type has the following structural problems. That is, vibration may be produced in the vane pump because its rotational shaft is eccentric, and the bearings may be easily damaged due to the unbalanced load applied to the rotational shaft. In addition, the gear type has a problem in that it is very simple in view of its structure but cannot be manufactured into a variable discharge volume type.

Disclosure Technical Problem An object of the present invention is to provide a rotary fluid pump that is configured to be not eccentric. Another object of the present invention is to provide a rotary fluid pump that can be easily converted into a fluid motor. A further object of the present invention is to provide a rotary fluid pump capable of adjusting its discharge volume. Technical Solution According to an aspect of the present invention, there is provided a fluid pump, comprising a cylindrical rotating chamber including first and second opposite wall surfaces and a third wall surface connecting the first and second wall surfaces, a rotor rotating within the rotating chamber about a rotational axis passing through the centers of the first and second wall surfaces and including a contact area slidably brought into contact with the third wall surface of the rotating chamber and a non-contact area spaced apart from the third wall surface, and a blocking which is slidably brought into close contact with the outer circumferential surface of the rotor and configured such that the blocking wall can be moved toward or away from the rotational axis, wherein the contact and non-contact areas are formed on an outer circumferential surface of the rotor which is formed around the rotational axis and faces the third wall surface, and a fluid suction port and a fluid discharge port are provided at opposite positions adjacent to the blocking wall in a state where the blocking wall is located between the suction and discharge ports. Preferably, ^"a check valve for preventing fluid from flowing in a backward direction is mounted in the discharge port. Further, the valve may be a reed valve. Further, the contact area formed on the outer circumferential surface of the rotor may be brought into surface contact with the third wall surface of the rotating chamber such that the contact area can simultaneously cover the suction and discharge ports at a certain position while the rotor rotates. Preferably, at least two contact areas of the rotor are arranged at an equal angular interval about the rotational axis, the blocking walls are also arranged at an equal angular interval about the rotational axis in number equal to the number of the contact areas of the rotor, and the suction and discharge ports are provided at opposite positions in a state where each of the blocking walls is located between the suction and discharge ports. Further, the non-contact area of the rotor may be curved in a convex manner. Further, the contact area of the rotor may be formed with a close contacting member which can move in a radial direction from the rotational axis and slidably brought contact with the third wall surface of the rotating chamber, and the rotor may include an accommodation groove in which the close contacting member is accommodated and a connection passage through which high-pressure fluid is transferred into the accommodation groove. Preferably, the fluid pump further comprises an elastic member for urging the blocking wall toward the rotational axis. Preferably, suction and discharge grooves, which are connected respectively to the suction and discharge ports and formed adjacent to the blocking wall, are provided at the opposite positions of the third wall surface of the rotating chamber, respectively. More preferably, at least two rotors are arranged in a row along the rotational axis, at least one blocking wall is provided for each rotor, and at least two rotating chambers in which the rotors are accommodated respectively is provided. Further, the rotors may be arranged to have a certain phase difference between each other. Furthermore, the suction and discharge grooves may be connected to each of the rotating chambers. Preferably, at least one pair of the suction and discharge ports are provided in and connected to each of the rotating chambers and are arranged to have a certain phase difference between each other. Preferably, the fluid pump further comprises a separating plate for separating the rotors from each other. The fluid pump may further comprise a discharge volume adjusting device for adjusting an amount of fluid discharged through the discharge ports. Preferably, the fluid pump is configured in such a manner that two blocking walls are provided to be symmetric with respect to the rotational axis, each pair of the suction and discharge ports are provided with the blocking wall interposed therebetween, and the discharge volume adjusting device includes a cylinder, a bellows capable of contracting and expanding in accordance with pressure of fluid at a suction side thereof, a piston connected to the bellows and moving within the cylinder, and a connection passage formed in the piston for allowing fluid discharged from the discharge port to be discharged to the outside or to be returned to the suction port while the piston reciprocates in the cylinder. The piston may be formed with a connection groove for connecting both ends of the piston. Preferably, the fluid pump is configured in such a manner that two blocking walls are provided to be symmetric with respect to the rotational axis, each pair of the suction and discharge ports are provided with the blocking wall interposed therebetween, and the discharge volume adjusting device includes a cylinder, a piston which moves within the cylinder, an elastic member for urging the piston toward one direction, and a connection passage which is formed in the piston to allow suction or discharge pressure of fluid to be applied to a guide passage formed in the blocking wall while the piston reciprocates in the cylinder. According to another aspect of the present invention, there is provided a fluid motor, comprising a cylindrical rotating chamber which includes first and second opposite wall surfaces and a third wall surface connecting the first and second wall surfaces, a rotor which rotates within the rotating chamber about a rotational axis passing through the centers of the first and second wall surfaces and includes a contact area slidably brought into contact with the third wall surface of the rotating chamber and a non-contact area spaced apart from the third wall surface, and a blocking wall which is slidably brought into close contact with the outer circumferential surface of the rotor and configured such that the blocking wall can be moved toward or away from the rotational axis, wherein the contact and non-contact areas are formed on an outer circumferential surface of the rotor which is formed around the rotational axis and faces the third wall surface, and a fluid inlet port and a fluid outlet port are provided at opposite positions adjacent to the blocking wall in a state where the blocking wall is located between the suction and discharge ports. Further, the contact area formed on the outer circumferential surface of the rotor may be brought into surface contact with the third wall surface of the rotating chamber such that the contact area can simultaneously cover the inlet and outlet ports at a certain position while the rotor rotates. Preferably, at least two contact areas of the rotor are arranged at an equal angular interval about the rotational axis, the blocking walls are also arranged at an equal angular interval about the rotational axis in number equal to the number of the contact areas of the rotor, and the inlet and outlet ports are provided at opposite positions in a state where each of the blocking walls is located between the suction and discharge ports. Further, the non-contact area of the rotor may be curved in a convex manner. Further, the contact area of the rotor may be formed with a close contacting member which can move in a radial direction from the rotational axis and slidably brought contact with the third wall surface of the rotating chamber, and the rotor may include an accommodation groove in which the close contacting member is accommodated and a connection passage through which high-pressure fluid is transferred into the accommodation groove. Preferably, the fluid motor further comprises an elastic member for urging the blocking wall toward the rotational axis. Preferably, inlet and outlet grooves, which are connected respectively to the inlet and outlet ports and formed adjacent to the blocking wall, are provided at the opposite positions of the third wall surface of the rotating chamber, respectively. More preferably, at least two rotors are arranged in a row along the rotational axis, at least one blocking wall is provided for each rotor, and at least two rotating chambers in which the rotors are accommodated respectively is provided. Further, the rotors may be arranged to have a certain phase difference between each other. Furthermore, the inlet and outlet grooves may be connected to each of the rotating chambers. Preferably, at least one pair of the inlet and outlet ports are provided in and connected to each of the rotating chambers and are arranged to have a certain phase difference between each other. The fluid motor may further comprise a separating plate for separating the rotors from each other.

Description of Drawings These and other objects and features of the present invention will be apparent to those skilled in the art from the following description of embodiments of the present invention given in conjunction with the accompanying drawings, in which: Fig. 1 is a perspective view of a fluid pump according to a first embodiment of the present invention, in which a housing of a main body is partially cut away such that the interior of the main body is exposed to the outside; Fig. 2 is a side view of the main body shown in Fig. 1, in which the housing is cut away to illustrate the interior of the main body; Fig. 3 is a sectional view schematically illustrating the interiors of the main body and discharge volume adjusting device shown in Fig. 1, in which the housing of the main body has been cut away perpendicular to a rotational shaft; Fig. 4 is a sectional view schematically illustrating the interiors of a main body and discharge volume adjusting device according to a second embodiment of the present invention, in which the housing of the main body has been cut away perpendicular to a rotational shaft; Fig. 5 is a sectional view of a fluid pump according to a third embodiment of the present invention taken perpendicular to a rotational shaft; Fig. 6 is a sectional view of a fluid pump according to a fourth embodiment of the present invention taken perpendicular to a rotational shaft; Fig. 7 is a sectional view of a fluid pump according to a fifth embodiment of the present invention taken perpendicular to a rotational shaft; Fig. 8 is a perspective view of a fluid pump according to a sixth embodiment of the present invention, in which a housing of a main body is partially cut away such that the interior of the main body can be exposed to the outside; Fig. 9 is a sectional view of the fluid pump of Fig. 8 taken along line A- A'; Fig. 10 (a) and (b) are perspective and exploded perspective views of another embodiment of a rotor of the fluid pump shown in Fig. 8; Fig. 11 is a perspective view of a fluid pump according to a seventh embodiment of the present invention, in which a housing of a main body is partially cut away such that the interior of the main body can be exposed to the outside; Fig. 12 is a sectional view of the fluid pump of Fig. 11 taken and spread along lines B-B' and C-C; Fig. 13 is a perspective view of a rotor of the fluid pump shown in Fig. 11; Fig. 14 is a perspective view of a fluid pump according to an eighth embodiment of the present invention, in which a housing of a main body is partially cut away such that the interior of the main body can be exposed to the outside; and Fig. 15 is a sectional view of the fluid pump of Fig. 14 taken along line D-D'.

Best Mode Figs. 1 to 3 show a fluid pump according to a first embodiment of the present invention. Referring to Fig. 1, a fluid pump 10 includes a main body 19 and a discharge volume adjusting device 90. Referring to Figs. 1 to 3, the main body 19 includes a housing 20, a rotational shaft 30, a rotor 40, a pair of blocking walls 50 and 52, and a pair of pressing plates 60 and 62. The housing 20 is configured in such a manner that a pair of radially and outwardly extending wings 24 are formed on a cylindrical body 22. The body 22 of the housing 20 includes a pair of circular end walls 221 and 222 and a sidewall 23 which connects the two end walls 221 and 222 with each other. A cylindrical space in which the rotational shaft 30, the rotor 40 and the two pressing plates 60 and 62 are included is defined in the body 22 of the housing 20. The internal space of the body 22 is divided into a rotating chamber 27 in which the rotor 40 rotatable about a rotational axis 100 is located, and two pressing chambers 28 and 29 which are defined between the two end walls 221 and 222 and the two pressing plates 60 and 62, respectively. The rotating chamber 27 is cylindrical and is defined by opposite first and second wall surfaces 101 and 102 and a third wall surface 103 connecting the first and second wall surfaces 101 and 102. The rotational axis 100 passes through the centers of the first and second wall surfaces 101 and 102. The opposite inner wall surfaces of the two pressing plates 60 and 62 become the first and second wall surfaces 101 and 102, and the inner wall surface of the sidewall 23 of the housing 20 located between the two pressing plates 60 and 62 becomes the third wall surface 103. Bearings 223 are installed at the centers of the two end walls 221 and 222 such that the rotational shaft 30 extending along the rotational axis 100 can be rotatably supported by the bearings, respectively. The two wings 24 are provided to extend outwardly from the sidewall 23 of the body 22. The two wings 24 are provided to be symmetric with each other at opposite sides of the body 22 with respect to the rotational shaft 30. In Figs. 1 to 3, it is shown that the wings 24 are provided below and above the body 22. The wings 24 taper in an outwardly radial direction. Guide passages 25 and 26, which communicate with the rotating chamber 27 in the body 22 and extend in a radial direction so as to guide the

^■ movement of the blocking walls 50 and 52, are provided within the wings 24, respectively. Hereinafter, among the two guide passages 25 and 26, a guide passage positioned at an upper side on these figures is called the first guide passage 25 and a guide passage positioned at a lower side on the figures is called the second guide passage 26. Opposite lateral ends of the first and second guide passages 25 and 26 in an extending direction of the rotational axis 100 meet opposite lateral ends of the rotor 40, respectively. Through-holes 251 and 261 for allowing the first and second guide passages 25 and 26 to communicate with the outer environment are formed at outer ends of wings 24 in a radial direction about the rotational axis 100 such that the two blocking walls 50 and 52 can be smoothly moved in the guide passages. Referring to Figs. 1 and 3, suction grooves 271 and 273 and discharge grooves 272 and 274 are provided on the third wall surface 103 of the rotating chamber 27 at ■ two opposite positions adjacent to the guide passages 25 and 26, respectively, in a state where the guide passages 25 and 26 are located between the grooves. The suction grooves 271 and 273 and the discharge grooves 272 and 274 are extend in parallel with the guide passages 25 and 26, and their opposite lateral ends are located within the limit of the opposite lateral ends of the rotor 40. This is because two close contacting members 42 and 44 of the rotor 40 to be explained later cannot be inserted and caught into the suction grooves 271 and 273 and the discharge grooves 272 and 274. Hereinafter, among the two grooves 271 and 273, the suction groove positioned next the first guide passage 25 is called the first suction groove 271 and the suction passage positioned next to the second guide passage 26 is called the second suction groove 273. Further, among the discharge passages 272 and 274, the discharge groove positioned next to the second guide passage 26 is called the first discharge groove 272 and the discharge groove positioned next to the first guide passage 25 is called the second discharge groove 274. As viewed from the figures, the first suction groove 271, the discharge groove 272, the second suction groove 273 and the second discharge groove 274 are sequentially disposed in a clockwise direction about the rotational shaft 30 from the first guide passage 25. The first and second suction grooves 271 and 273 are provided with first and second suction and discharge ports 275 and 277, respectively, which communicate with the outside of the housing 20. The first and second suction ports 275 and 277 are connected to first and second suction tubes 11 and 13, respectively. The first and second discharge grooves 272 and 274 are provided with first and second discharge ports 276 and 278, respectively, which communicate with the outside of the housing 20. The first and second discharge ports 276 and 278 are connected to first second discharge tubes 12 and 14, respectively. Referring again to Figs. 1 to 3, the rotational shaft 30 extending along the rotational axis 100 is rotatably supported by the bearings 223 installed at the centers of the two end walls 221 and 222 of the housing 20, respectively. One side of the rotational shaft 30 extends beyond the end wall 221 and is connected to a driving device (not shown). The rotational shaft 30 is rotated by means of the driving device. Referring still to Figs. 1 to 3, the rotor 40 takes the shape of a cylinder which extends along the rotational axis 100 such that its sectional area cut perpendicular to the axial direction is kept constant. It is preferred that the rotor be hollow except at its hub portions connected to the rotational shaft 30. Therefore, the weight of the rotor 40 can be reduced. Two contact areas 401 that are brought into contact with the third wall surface 103 of the rotating chamber 27 and two non-contact areas 402 that cause the two contact areas 401 to be connected with each other and are spaced apart from the third wall surface 103 of the rotating chamber 27 are provided on the outer surface that faces the third wall surface of the rotating chamber around the rotational axis 100. The two contact areas 401 are brought into surface contact with the third wall surface 103 such that they can be slid along the third wall surface. The circumferential length of the contact area 401 is sized such that each of the contact areas 401 blocks both the first and second suction grooves 271 and 273 and the first and second discharge grooves 272 and 274 at a certain position (corresponding to the state illustrated by the dotted line) during the rotation of the rotor 40. This configuration can preferably prevent the first and second suction ports 275 and 277 from directly communicating with the first and second discharge ports 276 and 278, respectively. Therefore, high-pressure fluid in the first and second discharge ports 276 and 278 can be prevented from flowing backward into the rotating chamber 27. Referring still to Figs. 1 to 3, the two contact areas 401 of the rotor 40 are provided with the close contacting members 42 and 44. The contacting members 42 and 44 take the shape of a slender, elongated bar and are inserted into the rotor 40 such that they can be moved in a radial direction. The rotor 40 is provided with two accommodation grooves 422 and 442 in which the two contacting members 42 and 44 are accommodated, respectively. An expanded space in which the high-pressure fluid can stay is provided in an internal portion of each of the accommodation grooves 422 and 442, and communication passages 424 and 444 for allowing the expanded space to communicate with the outside of the rotor 40 are further provided. The communication passages 424 and 444 are connected to the high-pressure side of the rotating chamber. The high-pressure fluid supplied to the accommodation grooves 422 and 442 through the communication passages 424 and 444 urges the contacting members 42 and 44 outwardly in a radial direction such that the contacting members 42 and 44 can be slid along the third wall surface 103 of the rotating chamber 27 while being brought into close contact with the third wall surface. Due to the above configuration, the contacting members 42 and 44 are always brought into close contact with the third wall surface 103 of the rotating chamber 27. Therefore, even though there is wear on the contacting members, fluid cannot leak out between the contacting members and the third wall surface of the rotating chamber. The non-contact areas 402 are shaped into a convex surface with a radius of curvature greater than that of the third wall surface 103 of the rotating chamber 27. The fluid is accommodated within the space defined between each of the non-contact areas 402 and the third wall surface 103 of the rotating chamber 27. The opposite lateral ends of the rotor 40 in the extending direction of the rotational axis 100 are brought into close contact with the first and second wall surfaces 101 and 102 of the rotating chamber 27, respectively. Referring still to Figs. 1 to 3, the two pressing plates 60 and 62 are cylindrical, and the rotational shaft 30 passes through the centers of the pressing plates 60 and 62. The two pressing plates 60 and 62 come into contact with the opposite lateral ends of the rotor 40 and can move linearly in an axial direction along the rotational shaft 30. Through-holes 61 and 63 are provided at positions adjacent to the discharge grooves 272 and 274. The high-pressure fluid is delivered through the through-holes 61 and 63 into the pressing chambers 28 and 29 defined between the two pressing plates 60 and 62 and the two end walls 221 and 222 of the housing 20 and urges the pressing plates 60 and 62 toward the rotor 40 such that the plates are brought into close contact with the rotor. Therefore, the leakage of fluid can be prevented. The two wall surfaces of the • two pressing plates 60 and 62, which face each other and are brought into close contact with the opposite lateral ends of the rotor 40, become the first and second wall surfaces 101 and 102 of the rotating chamber 27. Referring still to Figs. 1 to 3, the blocking walls 50 and 52 are accommodated in the first and second guide passages 25 and 26, respectively. Hereinafter, the blocking wall 50 received in the first guide passage 25 is called the first blocking wall, and the blocking wall 52 received in the second guide passages 26 is called the second blocking wall. The first and second blocking walls 50 and 52 have the same shapes as each other and are generally shaped as a rectangular plate. The first and second blocking walls 50 and 52 are well fitted into the guide passages 25 and 26, respectively, such that they can move linearly along the guide passages 25 and 26. Portions of the blocking walls 50 and 52 coming into contact with the outer circumferential surfaces of the rotor 40 are tapered. The two blocking walls 50 and 52 are subjected to forces of elastic members 70 such that they are always urged toward the rotational shaft 30, and they are always brought into close contact with the outer circumferential surfaces of the rotor 40 such that they can be slid along the outer circumferential surfaces. In this embodiment, the elastic member 70 is a compression coil spring. As the rotor 40 rotates, the two blocking walls 50 and 52 move linearly along the outer circumferential surfaces of the rotor 40. Referring to Figs. 1 and 3, the discharge volume adjusting device 90 includes a cylinder 92, a piston 94 and a bellows 96. The discharge tune 12 extending from the housing 20 is branched off into first and second passages 121 and 122 and connected to the cylinder 92. Further, a third passage 123 through which fluid is discharged to the outside is connected to the cylinder 92. A suction tube 131 branched off from the second suction tube 13 is also branched off into fourth and fifth passages 132 and 233 and connected to the cylinder 92. The fifth passage 133 is connected to the cylinder at a position adjacent to the bellows 96. Due to the movement of the piston 94, the first passage 121 communicates with the third passage 123 or the second passage 122 communicates with the fourth passage 132. The piston 94 is installed such that it can linearly move within the cylinder 92. The piston 94 is provided with a connection passage 941 extending perpendicular to a direction in which the piston 94 moves. The connection passage 941 is moved as the piston 94 moves linearly, and thus, the first and third passages 121 and 123 can communicate with each other or the second and fourth passages 122 and 132 can communicate with each other. In Fig. 3, it is shown that the connection passage 941 allows the first and third passages 121 and 123 to communicate with each other. A connection groove 942 is formed on an outer surface of the piston 94 along the moving direction of the piston. The connection groove 942 allows two spaces in the cylinder divided by the piston 94 to communicate with each other. The bellows 96 is accommodated in the cylinder 92 in such a manner that its one side is fixed to one end of the cylinder 92 and the other side is fixed to the piston 94. The length of the bellows 96 is increased or decreased according to the ambient pressure of fluid. That is, the length of the bellows 96 is decreased if the pressure of fluid transferred to the bellows 96 through the fifth passage 133 is greater than a reference value, while the length of the bellows 96 is increased if the pressure of fluid is less than the reference value. In addition, the fluid near the bellows 96 is transferred to the other space defined opposite to the piston 94 through the connection groove 942 formed on the outer surface of the piston 94 to facilitate smooth movement of the piston 94. The connection passage 941 of the piston 94 allows the first and third passages 121 and 123 to communicate with each other when the bellows 96 contracts, whereas the connection passage 941 of the piston 94 allows the second and fourth passages 122 and 132 to communicate with each other when the bellows 96 expands. Referring again to Figs. 1 to 3, the operation of the fluid pump according to the first embodiment of the present invention will be hereinafter described in detail. The driving device (not shown) causes the rotational shaft 30 to rotate in a clockwise direction with respect to the rotational axis 100. As the rotational shaft 30 rotates in a clockwise direction, the rotor 40 is also rotated in a clockwise direction with respect to the rotational axis 100. As the rotor 40 rotates in a clockwise direction, internal spaces of the rotating chamber 27 connecting to the first and second suction grooves 271 and 273 are expanded. More specifically, as the rotor 40 rotates in a clockwise direction, the two contact areas 401 and 402 are spaced far away from the first and second suction grooves 271 and 273 and the first and second blocking walls 50 and 52 move linearly along the outer circumferential surfaces of the rotor 40 in a state where they are brought into close contact with the outer circumferential surfaces. Therefore, the internal spaces of the rotating chamber 27 connecting to the first and second suction grooves 271 and 273 are expanded and accordingly fluid is introduced into the expanded spaces through the first and second suction grooves 271 and 273. At the same time, other internal spaces of the rotating chamber 27 connecting the first and second discharge grooves 272 and 274 are contracted and accordingly the fluid is discharged through the first and second discharge grooves 272 and 274 to the outside via the first and second discharge tubes 12 and 14. At this time, the high- pressure fluid at the discharge side is supplied into the accommodation grooves 422 and 442 through the communication passages 424 and 444 of the rotor 40 and urges the close contacting members 42 and 44 outwardly toward the wall surface of the rotating chamber 27 such that the leakage of fluid can be firmly prevented. In addition, the high-pressure fluid at the discharge side is also supplied into the pressing chambers 28 and 29 through the through-holes 61 and 63 formed in the two pressing plates 60 and 62 and urges and brings the pressing plates 60 and 62 toward and into the rotor 40 such that the leakage of fluid can be prevented. If the rotor 40 is located at the position shown by the dotted line, the contact areas 401 and 402 cover both the first and second suction grooves 271 and 273 and the first and second discharge grooves 272 and 274. Therefore, since the both the first and second suction grooves 271 and 273 and the first and second discharge grooves 272 and 274 do not communicate with each other through the rotating chamber 27, the backflow of fluid can be prevented. Accordingly, a check valve (also referred to as a "discharge valve") for preventing the backflow of fluid is not needed. Now, the operation of the discharge volume adjusting device will be described in detail with reference to Fig. 3. Similarly as described above, as the rotor 40 rotates in a clockwise direction, fluid is introduced into the rotating or operating chamber 27 through the first and second suction tubes 11 and 13. The fluid introduced through the first suction tube 11 is discharge through the first discharge tube 12, and the fluid introduced through the second tube 13 is discharged through the second discharge tube 14. At this time, the suction pressure of fluid introduced from the second suction tube 13 through the branched suction tube 131 and the fifth passage 133 is transferred around the bellows 96 in the cylinder 92 of the discharge volume adjusting device 90. The suction pressure is also transferred to the other space in the cylinder opposite to the bellows 96 through the connection groove 942 of the piston 94. First, the operation of the discharge volume adjusting device when the suction pressure of fluid is greater than the reference value will be explained. If the suction pressure is greater than the reference value, the fluid transferred into the cylinder 92 through the fifth passage 133 causes the piston 94 to be located at a position where the connection passage 941 of the piston 94 allows the first and third passages 121 and 123 to communicate with each other as shown in the figures. More specifically, suction pressure greater than the reference value is exerted around the bellows 96 and thus allows the bellows to contract. Furthermore, suction pressure greater than the reference value is transferred to the other space of the cylinder through connection groove 942 of the piston 94 such that the piston 94 is pushed downwardly to allow the bellows 94 to contract. Therefore, the piston 94 moves linearly in a direction in which the bellows 96 contracts, and accordingly, the connection groove 941 allows the first and third passages 121 and 123 to communicate with each other. In such a case, the fluid introduced through the first suction tube 11 is discharged to the outside via the first discharge tube 12 and the third passage 123. Further, the fluid introduced through the second suction tube 13 is discharged to the outside through the second discharge tube 14. That is, since the fluid is fully discharged to the outside through the first and second discharge tubes 12 and 14, the discharge volume can be kept at 100%. Next, the operation of the discharge volume adjusting device when the suction pressure is less than the reference value will be explained. In such a case, the connection passage 941 is located at a position where it allows the second and fourth passages 122 and 132 to communicate with each other, although this is not shown in the figures. More specifically, the suction pressure of fluid less than the reference value is transferred into the cylinder 92 through the fifth passage 133. Therefore, the pressure around the bellows 96 is less than the reference value, and accordingly, the bellows 96 expands to move the piston 94 upwardly. In addition, the suctioned fluid with a pressure less than the reference value is transferred to the other space opposite to the bellows 96 through the connection groove 942 of the piston 94 to facilitate the smooth movement of the piston 94. Consequently, the piston 94 moves in such a manner that the connection passage 941 allows the second and fourth passages 122 and 132 to communicate with each other. If the second and fourth passages 122 and 132 communicate with each other, the fluid introduced through the first suction tube 11 is discharged through the second discharge tube 12, and the discharged fluid is then introduced into the operating chamber 27 through the second suction tube 13 via the second and fourth passages 122 and 132. The fluid introduced through the second suction tube 13 is discharged to the outside through the second discharge tube 14. Since the discharge of fluid to the outside is made only through the second discharge tube 14, the discharge volume can be kept at 50%. Such a fluid pump can be employed in a compressor for coolants used in the air conditioning system of automobile. That is, the fluid pump can be used in such a manner that strong cooling can be maintained by discharging the coolants at a level of 100% when strong cooling is required (in a case where the suction pressure of the coolant is required to be higher), whereas weak cooling can be maintained by discharging the coolant at a level of 50% when weak cooling is required (in a case where the suction pressure of the coolant is required to be lower). Although a bellows was employed to drive the piston in this embodiment, the present mvention is not limited thereto. It can be understood by those skilled in the art that an electronically controlled solenoid device or a bypass valve can be used instead of a bellows. Fig. 4 shows a fluid pump according to a second embodiment of the present invention. Referring to Fig. 4, a fluid pump lOh includes a main body 19h and a discharge volume adjusting device 90h. The main body 19h further includes expanded portions 252h and 262h formed at distal ends of first and second guide passages 25h and 26h, in addition to the configuration of the main body of the fluid pump according to the first embodiment of the present invention shown in Figs. 1 to 3. In addition, no elastic members ("70" in Figs. 1 to 3) are provided in the first and second guide passages 25h and 26h. Since the other configuration of this embodiment is the same as the configuration of the fluid pump according to the previous embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. A second suction tube 13h is branched off into a branched suction tube 13 lh before it is connected to a housing 20h. A check valve 1311h is installed in the suction tube 13 lh. The check valve 1311h allows the fluid to flow from the second suction tube 13h only to the discharge volume adjusting device 90h through the branched suction tube 13 lh. The branched suction tube 13 lh is again divided into third and fourth passages 1312h and 1313h, which in turn are connected to the discharge volume adjusting device 90h. A second discharge tube 14h is branched off into a branched discharge tube 141h. The branched discharge tube 141h is again divided into first and second passages 1411h and 1412h, which in turn are connected to the discharge volume adjusting device 90h. The expanded portions 252h and 262h of the first and second guide passages 25h and 26h are connected to each other through a connection tube 99h. The connection tube 99h is branched off into fifth and sixth passages 991h and 992h, which in turn are connected to the discharge volume adjusting device 90h. Referring again to Fig. 4, the discharge volume adjusting device 90h includes a cylinder 92h, a piston 94h and an elastic member 96h. First to sixth passages 1411h, 1412h, 1312h, 1313h, 991h, and 992h are connected to the cylinder 92h. Among them, the fourth passage 1313h is connected to a space where the elastic member 96h is positioned, and the first passage 141 lh is connected to an end wall of the cylinder opposite to the elastic member 96h. Either the second and sixth passages 1412h and 992h or the third and fifth passages 1312h and 991h can communicate with each other through a connection passage 941h of the piston 94h to be explained later. The piston 94h is accommodated in the cylinder 92h such that it can be linearly moved therein. The piston 94h includes the connection passage 941h extending perpendicular to a direction in which the piston moves. The connection passage 94 lh is moved as the piston 94h moves linearly, and thus, either the second and sixth passages 1412h and 992h or the third and fifth passages 1312h and 99 lh can communicate with each other. In this figure, it is shown that the connection passage 941h allows the second and sixth passages 1412h and 992h to communicate with each other. A pushing force from the elastic member 96h and high discharge pressure transferred through the first passage

1411h are exerted on both ends of the piston 94, respectively. If the discharge pressure is less than the pushing force from the elastic member 96h, the piston 94h is located in such a manner that the connection passage 941h allows the second and sixth passages 1412h and 992h to communicate with each other as shown in the figure. On the other hand, if the discharge pressure is greater than the pushing force from the elastic member 96h, the piston 94h is located in such a manner that the connection passage 941h allows the third and fifth passages 1312h and 991h to communicate with each other. The elastic member 96h is a compression coil spring and urges the piston 94h toward the first passage 141 lh. Hereinafter, the operation of the second embodiment will be described in detail with reference to Fig. 4. When a rotor 40h rotates in a clockwise direction as described in the first embodiment shown in Figs. 1 to 3, fluid is introduced into an operating chamber 27h through first and second suction tubes llh and 13h. The fluid introduced the first suction tube llh is discharged through a first discharge tube 12h, and the fluid introduced through the second suction tube 13h is discharged through a second discharge tube 14h. At this time, the discharge pressure of fluid is transferred to the interior of the cylinder 92h of the discharge volume adjusting device 90h through the first passage 1411h of the branched discharge tube 141h and thus exerted on the piston against the pushing force from the elastic member 96h. First, the operation of the discharge volume adjusting device when the discharge pressure of fluid transferred through the first passage 141 lh is less than the pushing force from the elastic member 96h will be explained. In such a case, the piston 94h is urged by the force from the elastic member 96h, it is located at a position where the connection passage 941h allows the second and sixth passages 1412h and 992h to communicate with each other, as shown in the figure. Therefore, the high discharge pressure is transferred to the expanded portions 252h and 262h of the first and second guide passages 25h and 26h through the connection tube 99h to urge first and second blocking walls 50h and 52h toward a rotational shaft 30h. Accordingly, the first and second blocking walls 50h and 52h are brought into close contact with an outer circumferential surface of the rotor 40h, and consequently, the suction and discharge of fluid can be successfully made. Next, the operation of the discharge volume adjusting device when the discharge pressure of fluid transferred through the first passage 141 lh is greater than the force from the elastic member 96h will be explained. In such a case, the piston 94h is urged by the discharge pressure of fluid such that the connection passage 941h is located at a position where it allows the third and fifth passages 1312h and 991h to communicate with each other. Therefore, since the low suction pressure is transferred to the expanded portions 252h and 262h of the first and second guide passages 25h and 26h through the connection tube 99h, the first and second blocking walls 50h and 52h are separated from the outer circumferential surface of the rotor 40h, and thus, the suction and discharge of fluid cannot be made. That is, the fluid pump lOh is operated in such a manner that its discharge volume is kept at 100% when the discharge pressure is less than a reference value, whereas its discharge volume is kept at 0% when the discharge pressure is greater than the reference value. Such a fluid pump can be usefully employed in a fluid pump for use in the steering system of an automobile. Fig. 5 shows a fluid pump according to a third embodiment of the present invention. Referring to Fig. 5, a fluid pump lOf of this embodiment is the same as the fluid pump according to the first embodiment shown in Figs. 1 to 3 in view of their configurations, except the configurations of the rotor 40f and first and second discharge ports 276f and 278f. Two contact areas 401f of the rotor 40f are formed to be shorter in their circumferential direction such that they cannot simultaneously cover both first and second suction grooves 271f and 273f and first and second discharge grooves 272f and 274f. As the rotor 40f rotates, therefore, the first suction and discharge grooves 271f and 272f may communicate with each other or the second suction and discharge grooves 273f and 274f may communicate with each other. At this time, the fluid may flow backwardly from- the first and second discharge ports 276f and 278f toward first and second suction ports 275f and 277f. This can be prevented by means of two reed valves 279f to be explained later. The reed valves 279f are provided in the middle of the first and second discharge ports 276f and 278f, respectively. Each of the reed valves 279f is a valve that takes the shape of a thin plate and is curved by the fluid pressure to automatically open or close the discharge port. If the discharge pressure of fluid in the operating chamber 27f is greater than the pressure of fluid in the discharge tube 12f or 14f, the valve 279f is curved toward the discharge tube 12f or 14f to open the first or second discharge port 276f or 278f, as shown in the figure. On the other hand, if the discharge pressure of fluid _. in the operating chamber 27f is less than the pressure of fluid in the discharge tube 12f or 14f, the valve 279f is restored to an original state to close the first or second discharge port 276f or 278f, although this is not shown in the figure. The reed valves 279f prevent fluid from flowing in a backward direction when the first suction and discharge grooves 271f and 272f or the second suction and discharge grooves 273f and 274f communicate with each other. In addition, the reed valves 279f can prevent fluid from flowing instantly in a backward direction when the rotor 40f has been stopped. Although it has been described in this embodiment that the valves provided in the first and second discharge ports 276f and 278f are reed valves, the present invention is not limited thereto. It can be understood by those skilled in the art that another kind of check valve (also referred to as a "discharge valve") capable of preventing the backflow of fluid can be used instead of reed valves. Since the other configurations and operations of this embodiment are the same as those of the previous embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. Fig. 6 shows a fluid pump according to a fourth embodiment of the present invention. Referring to Fig. 6, portions of non-contact areas 402a of a rotor 40a, which are close to a rotational shaft 30a, are recessed in a concave form. The configuration and operation of the fluid pump 10a are the same as those of the fluid pump according to the previous embodiment shown in Figs. 1 to 3, except the shape of non-contact areas of the rotor 40a, and thus, detailed descriptions thereof will be omitted herein. Fig. 7 shows a fluid pump according to a fifth embodiment of the present invention. Referring to Fig. 7, three wings 24b formed at an equal angular interval (an interval of 120 degrees about a rotational shaft 30b) are provided around a body 22b of a housing 20b in the same manner as the wings 24 of the body of the fluid pump according to the previous embodiment shown in Figs. 1 to 3. Each of the wings 24b is provided with a guide passage 25b, 26 or 281b in which a blocking wall 50b, 52b or 54b and an elastic member 70b. Since the configuration thereof is the same as the first embodiment, detailed descriptions thereof will be omitted herein. In addition, a suction groove 271b, 273b or 291b and a discharge groove 272b, 274b or 292b, which are connected to a suction tube lib, 13b or 15b and a discharge tube 12b, 14b or 18b, respectively, are provided on a third wall surface 103b at two opposite positions adjacent to guide passages 25b, 26b or 281b, respectively, in a state where each of the guide passages is located between the relevant grooves. Since the configuration thereof is the same as the first embodiment, detailed descriptions thereof will be omitted herein. Three contact areas 401b formed at an equal angular interval (i.e., an interval of 120 degrees about the rotational shaft 30b) and three non-contact areas 402b connecting the adjacent contact areas 401b are provided on an outer circumferential surface of a rotor 40b. The contact areas 401b are brought into surface contact with the third wall surface 103b of a rotating chamber 27b, while the non-contact areas 402b are spaced apart from the third wall surface 103b of the rotating chamber 27b. Each of the three contact areas 401b of the rotor 40b is provided with an accommodation groove 422b, 442 or 462b and a connection passage 424b, 444b or 464b, and a close contacting member 42bm 44b or 46b is accommodated in the accommodation groove 422b, 442 or 462b. Since the above configuration is the same as that of the first embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. Furthermore, since the other configuration and operation of this embodiment are the same as those of the first embodiment, detailed descriptions thereof will be omitted herein. Figs. 8 to 10 illustrate a fluid pump according to a sixth embodiment of the present invention. Referring first to Figs. 8 and 9, a fluid pump 10c includes a housing 20c, a rotational shaft 30c, two rotors 46c and 48c, a separating plate 47c, two pressing plates 60c and 62c and four blocking walls 50c, 52c, 54c and 56c. The housing 20c is the substantially same as the housmg 20 of the first embodiment shown in Figs. 1 to 3, and includes a body 22c and two wings 24c. The interior of the body 22c is divided into a first rotating chamber 27c in which the first rotor 46c is accommodated, a second rotating chamber 32c in which the second rotor 48c is accommodated, and two pressing chambers 28c and 29c which are defined between two end walls 221c and 222c of the body 22c and the two pressing plates 60c and 62c, respectively. The first and second rotating chambers 27c and 32c are divided by the separating plate 47c. The first and second rotating chambers 27c and 32c communicate with each other through first and second suction grooves 271c and 273c and first and second discharge grooves 272c and 274c. Two guide passages 25c, 26c, 33c, ... (one of the passages is not shown in the figures), which are arranged in a row, are provided within each of the two wings 24c of the housing 20c. Through-holes 251c, 261c, 331c, ... (one of the holes is not shown in the figures) for allowing the guide passages 25c, 26c, 33c, ... (one of the passages is not shown in the figures) to communicate with the outside are provided at outward ends of the wings 24c. That is, the two through-holes are provided at each of the wings 24c.

The blocking wall 50c, 52c, 54c or 56c and an elastic member 70c are accommodated within each of the guide passages 25c, 26c, 33c, ... (one of the passages is not shown in the figures) of the housing 20c. Since the configuration and operation thereof are the same as those- of the first embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. Referring to Figs. 8 to 10 (a), the first rotor 46c, the separating plate 47c and the second rotor 48c are arranged in a row along a rotational axis 100c. The first and second rotors 46c and 48c have the same configuration as the rotor 40 of the first embodiment shown in Figs. 1 to 3. In the figures, close contacting members (corresponding to the contacting members 42 and 44 in Fig. 2), accommodation grooves for the contacting members (corresponding to the grooves 422 and 442 in Fig. 2) and connection passages (corresponding to the passages 424 and 444 in Fig. 2) are not shown. Contrary to the above configuration, the close contacting members and connection passages may be omitted. The first and second rotors 46c and 48c are disposed in such a manner that their phase difference is 90 degrees. The first rotor 46c is received in the first rotating chamber 27c, and the second rotor 48c is received in the second rotating chamber 32c. The separating piate 47c is shaped into a disc and positioned between the first and second rotors 46c and 48c. The first and second rotating chambers 27c and 32c are separated from each other by the separating plate 47c. The separating plate 47c may be integrally formed on the first and second rotors 46c and 48c as shown in Fig. 10 (a), or two separated portions 472c and 474c may be later fitted into and engaged with the first and second rotors 46c and 48c as shown in 10 (b). Since the other configuration is the same as that of fluid pump according to first embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. Hereinafter, the operation of this embodiment will be described in detail with reference to Figs. 8 and 9. As the rotational shaft 30c rotates in a clockwise direction, the two rotors 46c and 48c rotate accordingly in a clockwise direction. The first and second rotors 46c and 48c independently suck and/or discharge the fluid into and/or from the first and second rotating chambers 27c and 32c, respectively. Since the suction and discharge processes are the same as those in the first embodiment shown in

Figs. 1 to 3, detailed descriptions thereof will be omitted herein. First and second suction tubes lie and 13c and first and second discharge tubes 12c and 14c are connected to the first and second rotating chambers 27c and 32c through the first and second suction grooves 271c and 273c and the first and second discharge grooves 272c and 274c, respectively. Therefore, the fluid introduced in the first and second suction tubes lie and 13c is smoothly discharged to the first and second discharge tubes 12c and 14c via the first and second rotating chambers 27c and 32c, respectively. In addition, since the first and second rotors 46c and 48c have a phase difference of 90 degrees, the suction and discharge of fluid into and/or from the first and second rotating chambers 27c and 32c is also made with the same phase difference of 90 degrees.

Therefore, pulsation can be reduced as much. Figs. 11 to 13 show a fluid pump according to a seventh embodiment of the present invention. Referring to Figs. 11 and 12, a fluid pump lOd mcludes a housing 20d, a rotational shaft 30d extending along a rotational axis lOOd, two rotors 46d and 48d engaged with the rotational shaft 30d, two pressing plates 60d and 62d a separating plate 47d, and four blocking walls 50d, 52d, 54d and 56d. Referring to Figs. 11 and 12, the housing 20d is configured to include a cylindrical body 22d and four wings 24d extending from the body 22d outwardly in a radial direction. The body 22d includes two circular end walls 221d and 222d and a sidewall 223d connecting the two end walls 221d and 222d. The four wings 24d extend from the sidewall 223d in the same manner as the wings 24 in the first embodiment shown in Figs. 1 to 3. Two of the wings 24d are provided at opposite sides between one end wall 221 d and the middle portion of the sidewall 223d, and the other two wings 24d are provided at opposite sides between the other end wall 222d and the middle portion of the sidewall 223d such that the former is perpendicular to the latter. Each of the wings 24d is provided with a guide passage 25d, 26d, 33d or 34d in which the blocking wall 50d, 52d, 54d or 56d and an elastic member 70d are accommodated. Since the above configuration is the same as that of the first embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. The interior of the body 22d of the housing 20d is divided into a first rotating chamber 27d in which the first rotor 46d is accommodated, a second rotating chamber 32d in which the second rotor 48d is accommodated, and two pressing chambers 28d and 29d which are defined between two end walls 221d and 222d of the housing 20d and the two pressing plates 60d and 62d, respectively. The first and second rotating chambers 27d and 32d are divided by the separating plate 47d. The two opposite guide passages 25d and 26d are connected to the first rotating chamber 27d, and the other two opposite guide passages 33d and 34d are connected to the second rotating chamber 32d. Four suction tubes lid, 13d, 15d and 17d and four discharge tubes Ϊ2d, 14d, 16d and 18d, which are connected to the rotating chambers 27d and 32d, are provided at opposite positions adjacent to the guide passages 25d, 26d, 33d and 34d in such a state where each of the guide passages is located between the above relevant positions. Thus, the suction tubes lid and 13d and the discharge tubes 12d and 14d, which are connected to the rotating chamber 27d, are positioned to be 90 degrees with respect to the suction tubes 15d and 17d and the discharge tubes 16d and 18d, which are connected to the rotating chamber 32d. Referring to Figs. 11 to 13, there is no phase difference between the first and second rotors 4όd and 48d. The first rotor 46d is received in the first rotating chamber 27d of the housing 20d, and the second rotor 48d is received in the second rotating chamber 32d of the housing 20d. The first and second rotating chambers 27d and 32d are completely separated from each other by the separating plate 47d. Since the other configuration is the same as that of the previous embodiment shown in Figs. 8 to 10(b), detailed descriptions thereof will be omitted herein. Now, the operation of this embodiment will be described in detail with reference to Figs. 11 and 12. As the rotational shaft 30d rotates in a clockwise direction, the two rotors 46d and 48d are accordingly rotated in a clockwise direction. The suction and discharge of fluid can be made while the first and second rotors 46d and 48d rotate within the first and second rotating chambers 27d and 32d, respectively, in the same phase. Since the suction and discharge process is the same as that of the first embodiment shown in Figs. 1 to 3, detailed descriptions thereof will be omitted herein. The first and second rotors 46d and 48d rotate in the same phase, but the suction tubes lid and 13d and the discharge tubes 12d and 14d, which are connected to the first rotating chamber 27d, form an angular angle of 90 degrees with respect to the suction tubes 15d and 17d and the discharge tubes 16d and 18d, which are connected to the second rotating chamber 32d. Therefore, the suction and discharge of fluid can be made alternately in the first and. second rotating chambers 27d and 32d, and thus, the pulsation can also be reduced. Consequently, the same effects as the sixth embodiment shown in Figs. 8 to 10 will be obtained. Figs. 14 and 15 show a fluid pump according to an eighth embodiment of the present invention. Referring to Figs. 14 and 15, a fluid pump lOe includes a housing 20e, a rotational shaft 30e extending along a rotational axis lOOe, two rotors 46e and

48e engaged with the rotational shaft 30e, a separating plate 47e, and two blocking walls 50e and 54c. The housing 20e is configured to include a cylindrical body 22e and a single wing 24e extending from the body 22e in a radial direction. The cylindrical interior of the body 22e is divided into a first rotating chamber 27e in which the first rotor 46e is accommodated, and a second rotating chamber 32e in which the second rotor 48e is accommodated. The first and second rotating chambers 27e and 32e are divided by the separating plate 47e. The wing 24e is the same shape as that of the wings 24c of the embodiment shown in Fig. 8. The wing 24e is provided with two guide passages 25e and 33e in which the blocking walls 50e and 54e arranged in a row are accommodated. The blocking walls and guide passages are the same as those of the embodiment shown in Fig. 8. One guide passage 25e is connected to the first rotating chamber 27e, while the other guide passage 33e is connected to the second rotating chamber 32e. Referring still to Figs. 14 and 15, the first rotor 46e, the separating plate 47e and the second rotor 48e are arranged in a row along the rotational axis lOOe. The first and second rotors 46e and 48e are cylindrical and accommodated in the first and second rotating chambers 27e and 32e, respectively, such that they are engaged to be eccentric with the rotational shaft 30e. The first and second rotors 46e and 48e are arranged with a phase difference of 180 degrees. Contact areas 401e that come into surface contact with third wall surfaces 103e of the first and second rotating chambers 27e and 32e are formed on outer circumferential surfaces of the first and second rotors 46e and 48e at positions farthest from the rotational shaft 30e. An internal space of the body 22e is divided into the first and second rotating chambers 27e and 32e by the separating plate 47e. Since the other configuration is the same as that of the embodiment shown in Fig. 8, detailed descriptions thereof will be omitted herein. Hereinafter, the operation of this embodiment will be described in detail with reference to Figs. 12 and 13. As the rotational shaft 30e rotates in a clockwise direction, the rotor assembly 40e is accordingly rotated in a clockwise direction. As the first rotor 46e of the rotor assembly 40e rotates in a clockwise direction, the space at the suction side of the first rotating chamber 27e expands and fluid is thus automatically introduced in the space. As the first rotor 46e is further rotated, the introduced fluid is pressurized and then discharged. That is, the fluid is introduced during one revolution of the rotor, and the introduced fluid is then discharged during the next cycle of the rotor. The suction and discharge of fluid is made while the above processes are repeated. The second rotor 48e of the rotor assembly 40e can perform the suction and discharge of fluid into and from the second rotating chamber 32e in the same manner as the first rotor 46e. The second rotor 48e has a phase difference of 180 degrees with respect to the first rotor 46e, and thus, the suction and discharge of fluid into and from the first and second rotating chambers 27e and 32e are alternately performed. That is, during one revolution of the rotor, the suction of fluid is made within one rotating chamber and the discharge of fluid is made within another rotating chamber. Therefore, both the suction and discharge of fluid are made once every revolution of the rotor. Since the other operations are the same as those of the embodiment shown in Fig. 8, detailed descriptions thereof will be omitted herein. Although the present invention has been hitherto described as to the use of fluid pump, it is not limited thereto. It will be readily understood by those skilled in the art that the rotational shaft can be rotated by forcibly pumping fluid into the rotating chambers from the outside through the suction ports except in case of the embodiments of Fig. 5 in which the discharge valves are employed. Accordingly, it will be understood by those skilled in the art that the present invention includes a fluid motor as well as a fluid pump.

Claims

1. A fluid pump, comprising: a cylindrical rotating chamber including first and second opposite wall surfaces and a third wall surface connecting the first and second wall surfaces; a rotor rotating within the rotating chamber about a rotational axis passing through the centers of the first and second wall surfaces and including a contact area slidably brought into contact with the third wall surface of the rotating chamber and a non-contact area spaced apart from the third wall surface, said contact and non-contact areas being formed on an outer circumferential surface of the rotor which is formed around the rotational axis and faces the third wall surface; and a blocking wall slidably brought into close contact with the outer circumferential surface of the rotor and configured such that the blocking wall can be moved toward or away from the rotational axis, wherein a fluid suction port and a fluid discharge port are provided at opposite positions adjacent to the blocking wall in a state where the blocking wall is located between the suction and discharge ports.

2. The fluid pump as claimed in claim 1, wherein a check valve for preventing fluid from flowing in a backward direction is mounted in the discharge port.

3. The fluid pump as claimed in claim 2, wherein the valve is a reed valve,

4. The fluid pump as claimed in claim 1, wherein the contact area formed on the outer circumferential surface of the rotor is brought into surface contact with the third wall surface of the rotating chamber such that the contact area can simultaneously cover the suction and discharge ports at a certain position while the rotor rotates.

5. The fluid pump as claimed in claim 4, wherein at least two contact areas of the rotor are arranged at an equal angular interval about the rotational axis, the blocking walls are also arranged at an equal angular interval about the rotational axis in number equal to the number of the contact areas of the rotor, and the suction and discharge ports are provided at opposite positions in a state where each of the blocking walls is located between the suction and discharge ports.

6. The fluid pump as claimed in claim 5, wherein the non-contact area of the rotor is curved in a convex manner.

7. The fluid pump as claimed in any one of claims 1 to 6, wherein the contact area of the rotor is formed with a close contacting member which can move in a radial direction from the rotational axis and slidably brought contact with the third wall surface of the rotating chamber, and the rotor includes an accommodation groove in which the close contacting member is accommodated and a connection passage through which high-pressure fluid is transferred into the accommodation groove.

8. The fluid pump as claimed in any one of claims 1 to 6, further, comprising an elastic member for urging the blocking wall toward the rotational axis.

9. The fluid pump as claimed in any one of claims 1 to 6, wherein suction and discharge grooves, which are connected respectively to the suction and discharge ports

- and formed adjacent to the blocking wall, are provided at the opposite positions of the third wall surface of the rotating chamber, respectively.

10. The fluid pump as claimed in claim 1, wherein at least two rotors are arranged in a row along the rotational axis, at least one blocking wall is provided for each rotor, and at least two rotating chambers in which the rotors are accommodated respectively is provided.

11. The fluid pump as claimed in claim 10, wherein the rotors are arranged to have a certain phase difference between each other.

12. The fluid pump as claimed in claim 11, wherein the suction and discharge grooves as defined in claim 9 are connected to each of the rotating chambers.

13. The fluid pump as claimed in claim 10, wherein at least one pair of the suction and discharge ports are provided in and connected to each of the rotating chambers and are arranged to have a certain phase difference between each other.

14. The fluid pump as claimed in any one of claims 10 to 13, further comprising a separating plate for separating the rotors from each other.

15. The fluid pump as claimed in any one of claims 1 to 4, further comprising a discharge volume adjusting device for adjusting an amount of fluid discharged through the discharge ports.

16. The fluid pump as claimed in claim 15, wherein two blocking walls are provided to be symmetric with respect to the rotational axis, and each pair of the suction and discharge ports are provided with the blocking wall interposed therebetween, and wherein the discharge volume adjusting device includes: a cylinder; a bellows capable of contracting and expanding in accordance with pressure of fluid at a suction side thereof; a piston connected to the bellows and moving within the cylinder; and a connection passage formed in the piston for allowing fluid discharged from the discharge port to be discharged to the outside or to be returned to the suction port while the piston reciprocates in the cylinder.

17. The fluid pump as claimed in claim 16, wherein the piston is formed with a connection groove for connecting both ends of the piston.

18. The fluid pump as claimed in claim 15, wherein two blocking walls are provided to be symmetric with respect to the rotational axis, and each pair of the suction and discharge ports are provided with the blocking wall interposed therebetween, and wherein the discharge volume adjusting device mcludes: a cylinder; a piston moving within the cylinder; an elastic member for urging the piston toward one direction; and a connection passage formed in the piston for allowing suction or discharge pressure of fluid to be applied to a guide passage formed in the blocking wall while the piston reciprocates in the cylinder.

19. A fluid motor, comprising: a cylindrical rotating chamber including first and second opposite wall surfaces and a third wall surface connecting the first and second wall surfaces; a rotor rotating within the rotating chamber about a rotational axis passing through the centers of the first and second wall surfaces and including a contact area slidably brought into contact with the third wall surface of the rotating chamber and a non-contact area spaced apart from the third wall surface, said contact and non-contact areas being formed on an outer circumferential surface of the rotor which is formed around the rotational axis and faces the third wall surface; and a blocking wall slidably brought into close contact with the outer circumferential surface of the rotor and configured such that the blocking wall can be moved toward or away from the rotational axis, wherein a fluid inlet port and a fluid outlet port are provided at opposite positions adjacent to the blocking wall in a state where the blocking wall is located between the suction and discharge ports.

20. The fluid motor as claimed in claim 19, wherein the contact area formed on the outer circumferential surface of the rotor is brought into surface contact with the third wall surface of the rotating chamber such that the contact area can simultaneously cover the inlet and outlet ports at a certain position while the rotor rotates.

21. The fluid motor as claimed in claim 20, wherein at least two contact areas of the rotor are arranged at an equal angular interval about the rotational axis, the blocking walls are also arranged at an equal angular interval about the rotational axis in number equal to the number of the contact areas of the rotor, and the inlet and outlet ports are provided at opposite positions in a state where each of the blocking walls is located between the suction and discharge ports.

22. The fluid motor as claimed in claim 21, wherein the non-contact area of the rotor is curved in a convex manner.

23. The fluid motor as claimed in any one of claims 19 to 22, wherein the contact area of the rotor is formed with a close contacting member which can move in a radial direction from the rotational axis and slidably brought contact with the third wall surface of the rotating chamber, and the rotor includes an accommodation groove in which the close contacting member is accommodated and a connection passage through which high-pressure fluid is transferred into the accommodation groove.

24. The fluid motor as claimed in any one of claims 19 to 22, further comprising an elastic member for urging the blocking wall toward the rotational axis.

25. The fluid pump as claimed in any one of claims 19 to 22, wherein inlet and outlet grooves, which are connected respectively to the inlet and outlet ports and formed adjacent to the blocking wall, are provided at the opposite positions of the third wall surface of the rotating chamber, respectively.

26. The fluid motor as claimed in claim 19, wherein at least two rotors are arranged in a row along the rotational axis, at least one blocking wall is provided for each rotor, and at least two rotating chambers in which the rotors are accommodated respectively is provided.

27. The fluid motor as claimed in claim 26, wherein the rotors are arranged to have a certain phase difference between each other.

28. The fluid motor as claimed in claim 27, wherein the inlet and outlet grooves as defined in claim 25 are connected to each of the rotating chambers.

29. The fluid motor as claimed in claim 26, wherein at least one pair of the inlet and outlet ports are provided in and connected to each of the rotating chambers and are arranged to have a certain phase difference between each other.

30. The fluid motor as claimed in claim 26, further comprising a separating plate for separating the rotors from each other.