WO2003067091A1

WO2003067091A1 - Fluid pump and motor

Info

Publication number: WO2003067091A1
Application number: PCT/KR2003/000258
Authority: WO
Inventors: Kyung-Yul Hyun
Original assignee: Kyung-Yul Hyun
Priority date: 2002-02-08
Filing date: 2003-02-06
Publication date: 2003-08-14
Also published as: AU2003206241A1

Abstract

The fluid pump (10) includes a housing (20), two rotors (50, 50a), two moving members (80, 80a) and two spring (99, 99a). The housing is connected with inflow pipe (34) and discharge pipe (36). The two rotors is paralleled and engage each other to rotate on the contrary direction respectively. The rotor has plural projections (52) movable to radius direction. The two moving members move to control the width of pathway (501) for the fluid flow. The two springs urges the moving members so that the moving members move for the width of pathway to widen.

Description

FLUID PUMP AND MOTOR

Technical Field

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

Background Art

A fluid pump is a device that sucks and discharges a fluid such as oil through rotation of a shaft thereof by a driving unit, and a fluid motor is a device that receives a fluid discharged from a pump and causes a shaft to rotate. The fluid pump and the fluid motor are generally the same in view of their structures.

Fluid pumps are classified into a constant discharge volume type pump and a variable discharge volume type pump in view of their functions. The constant discharge volume type pump is a pump with a constant discharge volume per revolution. To obtain a desired discharge volume, the number of revolutions should be changed or a flow rate control valve should be incorporated therein. In the variable discharge volume type pump, a discharge volume per revolution is changed in such a manner that the displacement of the pump is changed to obtain the desired discharge volume. The variable discharge volume type pump can provide a circuit with energy closest to a required level by changing the discharge volume.

Fluid pumps are classified into reciprocating pumps, rotary pumps, centrifugal pumps and the like in view of their structures. A Piston pump is representative of reciprocating pumps, in which a piston reciprocates within a cylinder and intake and exhaust valves are alternately opened and closed to suck and discharge liquid. In rotary pumps, suction and discharge of a fluid are made by a rotating rotor. As for typical examples of a rotary pump, there are vane pumps with sliding vanes and gear pumps with two gears engaged with each other. In a vane pump, the extendable and retractable vanes are mounted on an eccentric rotor so as to suck and discharge fluid. In a gear pump, the fluid is sucked and discharged by means of the two gears that are engaged and rotated with each other. Although the piston and vane pumps are relatively easy to manufacture as a variable type with a variable discharge volume, the gear pumps are difficult to manufacture as a variable type.

Summary of the Invention

An object of the present invention is to provide a fluid pump and a fluid motor each of which has a simplified structure with two rotors. Another object of the present invention is to provide a variable type fluid pump and fluid motor each of which has two rotors.

A further object of the present invention is to provide a fluid pump in which a discharge volume is controlled by means of suction pressure.

A still further object of the present invention is to provide a rotary fluid pump which produces less noise.

A still further object of the present invention is to provide a rotary fluid pump for multi-stage compression.

A still further object of the present invention is to provide a rotor for a rotary fluid pump, which can be easily manufactured. According to one aspect of the present invention, there is provided a fluid pump comprising a housing provided with an inflow pipe through which a fluid is introduced into the housing and a discharge pipe through which the fluid is discharged from the housing; and first and second rotors that are disposed parallel to each other within the housing and rotate about respective rotation axes thereof while being engaged with each other. The first rotor includes a main body that rotates about the rotation axis of the first rotor, and plural cylindrical projection members that are installed on the main body and disposed parallel to the rotation axis of the rotor so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body. The fluid pump further comprises a pathway forming wall partially surrounding the first rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the first rotor and comes into contact with the projection members. The second rotor includes a main body that rotates about the rotation axis of the second rotor and is provided with grooves into which the protruding portions of the projection members of the first rotor can be inserted. According to another aspect of the present invention, there is provided a fluid motor, comprising a housing; and first and second rotors that are disposed parallel to each other within the housing and rotate about respective rotation axes thereof while being engaged with each other. The first rotor includes a main body that rotates about the rotation axis of the first rotor, and plural cylindrical projection members that are installed on the main body so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body of the rotor. The fluid pump further comprises a pathway forming wall partially surrounding the first rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the first rotor and comes into contact with the projection members. The second rotor includes a main body that rotates about the rotation axis of the second rotor and is provided with grooves into which the protruding portions of the projection members of the first rotor can be inserted.

According to a further aspect of the present invention, there is provided a fluid pump, comprising a housing provided with an inflow pipe and a discharge pipe, a fluid being introduced through the inflow pipe into and discharged through the discharge pipe from the housing; two rotational shafts that run parallel with each other within the housing and rotate in opposite directions; and rotor pairs each of which includes two rotors that are coupled to the respective shafts and engaged with each other to rotate together. One of the two rotors of each of the rotor pairs includes at least two projections protruding radially, and the other rotor includes accommodation grooves in which the projections can be accommodated. The rotor pairs are two or more rotor pairs, and rotors on the same rotation axis are coupled to the relevant rotational shaft with different phase differences such that the respective rotor pairs are engaged at different timings. According to a still further aspect of the present invention, there is provided a fluid pump, comprising two rotational shafts that run parallel with each other and rotate in opposite directions; and rotor pairs each of which includes two rotors that are coupled to the respective shafts and engaged with each other to rotate together. Each of the rotors is formed by stacking plural thin plate members with the same cross section as the rotor.

Brief Description of the Drawings

Preferred embodiments of the present invention will be described with reference to the accompanying drawings so that those skilled in the art can clearly understand the objects and features of the present invention.

FIG. 1 is a partially cut-away perspective view of a pump according to a first embodiment of the present invention, showing the interior of a housing of the pump;

FIG. 2 is a sectional side view of the pump of FIG. 1, showing the interior of the housing;

FIG. 3 is a sectional view showing the interior of an operating chamber with the housing of the pump in FIG. 1 cut perpendicularly to a rotational shaft, wherein the positions of first and second oil pathway holes in a side plate are illustrated by dotted lines; FIG. 4 is a perspective view of the side plate of the pump shown in FIG. 1;

FIG. 5 is a sectional view of an operating chamber of a pump according to a second embodiment of the present invention;

FIG. 6 is an exploded perspective view of a rotor of FIG. 5; FIG. 7 is a sectional view of an operating chamber of a pump according to a third embodiment of the present invention;

FIG. 8 is a sectional view of an operating chamber of a pump according to a fourth embodiment of the present invention;

FIG. 9 is a sectional view of an operating chamber of a pump according to a fifth embodiment of the present invention; FIG. 10 is a sectional view of an operating chamber of a pump according to a sixth embodiment of the present invention;

FIG. 11 is a sectional view of an operating chamber of a pump according to a seventh embodiment of the present invention;

FIG. 12 is a sectional view of an operating chamber of a pump according to an eighth embodiment of the present invention;

FIG. 13 is a sectional view of an operating chamber of a pump according to a ninth embodiment of the present invention;

FIG. 14 is a sectional view of an operating chamber of a pump according to a tenth embodiment of the present invention; FIG. 15 is a sectional view of an operating chamber of a pump according to an eleventh of the present invention, showing a state where a low pressure side is opened and a high pressure side is closed in a pressure regulating unit;

FIG. 16 is a sectional view of the pressure regulating unit of the pump in FIG. 15, showing a state where the high pressure side is opened and the low pressure side is closed;

FIG. 17 is a partially cut-away perspective view of a fluid pump according to a twelfth embodiment of the present invention, showing the interior of a housing of the fluid pump;

FIG. 18 is a sectional view showing the interior of an operating chamber with the housing of the fluid pump in FIG. 12 cut perpendicularly to a rotational shaft;

FIG. 19 is a perspective view of a rotor and the rotational shaft connected to the rotor of the fluid pump in FIG. 1;

FIG. 20 is a sectional view showing the interior of an operating chamber with a housing of a fluid pump according to a thirteenth embodiment of the present invention cut perpendicularly to a rotational shaft;

FIG. 21 is a perspective view of a rotor and the rotational shaft connected to the rotor of a fluid pump according to a fourteenth embodiment of the present invention;

FIG. 22 is a perspective view of an intermediate separation plate in FIG. 21;

FIG. 23 is a perspective view showing another embodiment of the intermediate separation plate in FIG. 21; FIG. 24 is a view showing a configuration of a fluid pump for one-stage compression with the rotor in FIG. 21;

FIG. 25 is a view showing a configuration of a fluid pump for two-stage compression with the rotor in FIG. 21; and FIG. 26 is a perspective view of a rotor and a rotational shaft connected to the rotor of a fluid pump according to a fifteenth embodiment of the present invention.

Detailed Description of the Embodiments

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIGS. 1, 2 and 3 show a pump according to a first embodiment of the present invention. FIG. 1 is a partially cut-away perspective view of the pump, showing the interior of a housing of the pump; FIG. 2 shows the interior of the housing by longitudinally cutting the housing; and FIG. 3 shows the interior of an operating chamber by cutting the housing perpendicularly to a rotational shaft. Referring to FIGS. 1, 2 and 3, the pump 10 comprises a housing 20, and two rotational shafts 40 and 40a, two rotors 50 and 50a, two side plates 70 and 70a, two moving members 80 and 80a, and two coil springs 99 and 99a, which are installed within the housing 20. Referring to FIGS. 1, 2 and 3, the housing 20 is in the form of a rectangular parallelepiped, and comprises a bottom 22 and a top wall 24 facing each other, first and third sidewalls 26 and 30 facing each other, and second and fourth sidewalls 28 and 32 facing each other. The interior of the housing 20 is divided into three spaces, i.e. the first and second pressurization chambers 21 and 25 and an operating chamber 23, by first and second side plates 70 and 70a to be described later which are installed parallel to the second and fourth sidewalls 28 and 32. The first pressurization chamber 21 is a space between the second sidewall 28 and the first side plate 70, and the second pressurization chamber 25 is a space between the fourth sidewall 32 and the second side plate 70a. The operating chamber 23 is a space between the first side plate 70 and the second side plate 70a. First and second separation walls 27 and 29 respectively spaced apart from the top wall 24 and the bottom 22 of the housing 20 are disposed in the operating chamber 23. The first and second separation walls 27 and 29 are parallel to the top wall 24 and the bottom 22 of the housing 20 and coupled integrally with the first and third sidewalls 26 and 30. Referring to FIG. 3, the operating chamber is divided into three spaces, i.e. an upper pressure regulation chamber 33, a lower pressure regulation chamber 35 and a rotation chamber 33, by the first and second separation walls 27 and 29. The upper pressure regulation chamber 31 is a space between the upper wall 24 of the housing 20 and the first separation wall 27, and the lower pressure regulation chamber 35 is a space between the bottom 22 of the housing 20 and the second separations wall 29. The rotation chamber 33 is a space between the first separation wall 27 and the second separations wall 29.

Referring to FIGS. 1, 2 and 3, an inflow pipe 34 communicating with the interior of the rotation chamber 33 is provided at the center of the first sidewall 26 of the housing 20. A discharge pipe 36 connecting the interior and exterior of the rotation chamber 33 is provided at the center of the third sidewall 30 of the housing 20.

The discharge pipe 36 is connected to two connection pipes 361 and 362 that communicate with the upper pressure regulation chamber 31 and the lower pressure regulation chamber 35, respectively. Pressure of the fluid discharged through the two connection pipes 361 and 362 is transferred to the upper pressure regulation chamber 31 and the lower pressure regulation chamber 35.

Referring to FIGS. 1, 2 and 3, two rotational shafts 40 and 40a that traverse between the second and fourth sidewalls 28 and 32 are provided one above the other within the housing 20. Both of the two rotational shafts 40 and 40a pass through the rotation chamber 33. The upper rotational shaft 40 of the two rotational shafts 40 and 40a extends to the outside while passing through the second sidewall 28 and is coupled to a driving motor, not shown, so as to drive the pump 10. The two rotational shafts 40 and 40a are rotatably coupled to the second and fourth sidewalls 28 and 32 and supported by ball bearings 37, respectively. The two rotational shafts 40a and 40a are provided with gears 401 and 401a that are engaged with each other in the first pressurization chamber 21. The two gears are identical so that the rotational speeds and rotating angles of the two rotational shafts 40 and 40a correspond to each other.

Referring to FIGS. 1 and 3, two cylindrical rotors 50 and 50a in the same form that are coupled to the two rotational shafts 40 and 40a penetrating the centers of the rotors are provided in the rotation chamber 33 of the operating chamber 23. The rotor 50 or 50a includes a main body 54 or 54a, and four cylindrical projection members 52 or 52a that are accommodated in the main body 54 or 54a and come into contact with a pathway forming wall 82 or 82a to be described later. The main body 54 or 54a includes four projection member accommodation grooves 56 or 56a that are formed radially, and intermediate grooves 58 or 58a formed between the projection member accommodation grooves 56 or 56a. Each of the projection member accommodation grooves 56 includes a flat bottom 561 and two sidewalls 562 extending vertically and outwardly from both ends of the bottom 561. Distal ends of the two sidewalls 562 meet at an outer periphery of the main body 54 and define an opening of the projection member accommodation groove 56. The distal ends of the two sidewalls 562 take the shape of an arc so that the distance between the two sidewalls 562 can be decreased toward the opening. At this time, the width of the bottom 561 is substantially identical to or slightly greater than the diameter of each of the projection members 52 so that the projection member can slide therein, and the depth of the projection member accommodation groove 56 is larger than the diameter of the projection member 52. The projection members 52 and 52a accommodated in the projection member accommodation grooves 56 and 56a move toward the openings of the accommodation grooves 56 and 56a by means of centrifugal force when the rotors 50 and 50a rotate. At this time, the width of each of the openings of the accommodation grooves 50 and 56a is smaller than the diameter of each of the projection members 52 and 52a so that the projection members 52 and 52a cannot escape from the accommodation grooves 56 and 56a. The respective projection member accommodation grooves 56 and 56a are radially disposed at an angle of 90 degrees between adjacent grooves on the rotors 50 and 50a. Surfaces of the intermediate grooves 58 and 58a formed between the respective projection member accommodation grooves 56 and 56a are in the form of an arc. The size of each of the intermediate grooves 58 and 58a is determined to the extent that a portion of each of the projection members can be accommodated therein when each of the projection members 52 and 52a protrudes toward the exterior of each of the accommodation grooves 56 and 56a to the maximum extent.

The two rotors 50 and 50a are disposed such that one of the projection member accommodation grooves 56 and 56a faces one of the intermediate grooves 58 and 58a at a position where the two rotors 50 and 50a come into contact with each other. Further, when one of the projection members 52 and 52a protrudes, the projection member is accommodated in one of the intermediate grooves 58 and 58a that the projection member faces. Referring to FIGS. 1, 2 and 3, an upper moving member 80 is provided over the upper pressure regulation chamber 31 and the rotation chamber 33, and a lower moving member 80a is provided over the lower pressure regulation chamber 35 and the rotation chamber 33. The upper moving member 80 includes a pressure plate 84 positioned in the upper pressure regulation chamber 31, the pathway forming wall 82 positioned in the rotation chamber 33, and connection posts 86 connecting the pressure plate 84 and the pathway forming wall 82. The pressure plate 84 is a flat rectangular plate of which respective sides are in contact with the first and third sidewalls 26 and 30 and the first and second side plates 70 and 70a. However, since the sides of the pressure plate are not fixed thereto, the pressure plate can move in the upper pressure regulation chamber 31. The upper pressure regulation chamber 31 is divided into a pressurization chamber

311 above the pressure plate 84 and a spring chamber 312 below the pressure plate 84 by means of the pressure plate 84. The pressurization chamber 311 communicates with the discharge pipe 36 through the connection pipe 361 installed in the third sidewall 30 of the housing 20. A coil spring 99 of which both ends are in contact with the pressure plate 84 and the first separation wall 27 is provided at the center of the spring chamber 312.

Referring to FIGS. 1 and 3, the pathway forming wall 82 of the upper moving member 80 includes a semicircular, curved portion 821 with a "U-shaped" section, and two parallel straight portions 822 which extend linearly from ends of the curved portion 821. The pathway forming wall 82 is positioned such that outer surfaces of the straight portions 822 are in contact with the first and third sidewalls 26 and 30 of the housing 20 and an outer surface of the curved portion 821 faces the first separation wall 27. The rotor 50 is disposed between the two parallel straight portions 822 of the pathway forming wall 82, and the projection members 52 come into contact with an inner surface of the pathway forming wall 82. Referring to FIGS. 2 and 3, the four cylindrical connection posts 86 which penetrate through the first separation wall 27 and each of which is coupled to the pressure plate 84 and the curved portion 821 of the pathway forming wall 82 at both ends thereof are provided between the pressure plate 84 and the pathway forming wall 82. Since the configurations of the lower moving member 80a and the lower pressure regulation chamber 35 are the same as the upper moving member 80 and the upper pressure regulation chamber 31 described above, a detailed description thereof will be omitted.

FIG. 4 is a perspective view of the second side plate 70a of the pump 10 shown in FIG. 2. Referring to FIGS. 1, 2 and 4, the second side plate 70a is a rectangular plate and includes two shaft-penetrating holes 72 and 74 through which the two rotational shafts 40 and 40a can penetrate, a first fluid pathway hole 76 positioned on the discharge side of the rotation chamber 33, two second fluid pathway holes 78 and 78a positioned between the two shaft-penetrating holes 72 and 74, and circular grooves 789 positioned around the two shaft-penetrating holes 72 and 74 and passing through the two second fluid pathway holes 78 and 78a, and arcuate fluid slots 77 and 79 provided in the vicinity of the two shaft-penetrating holes 72 and 74, respectively.

Referring to FIG. 3, the second side plate 70a is placed in the rear of the rotation chamber. The positions of the first fluid pathway hole 76, the second fluid pathway holes 78 and 78a, the circular grooves 789, and the fluid slots 77 and 79 are illustrated by solid and dotted lines in the rotation chamber. The first fluid pathway hole 76 is located near the first discharge pipe 36. The two second fluid pathway holes 78 and 78a are located in places where they communicate with lower portions of the respective projection member accommodation grooves 56 and 56a of the two rotors 50 and 50a. Each of the two circular grooves 789 is sized to connect the four projection member accommodation grooves 56 or 56a formed in each of the rotors 50 and 50a. Each of the circular grooves 789 allows the four projection member accommodation grooves formed in each of the rotors to communicate with one another so that oil contained therein can flow in and out from the grooves. This is to facilitate the escape of oil contained in the projection member accommodation groove in which a retracting projection member pushed by one of the pathway forming walls 82 and 82a and retracted into one of the rotors 50 and 50a is placed. The two fluid slots 77 and 79 are located on the suction side and are formed to include pathways (through which the fluid flows) between the pathway forming walls 82 and 82a and the rotors 50 and 50a. This provides a configuration by which when the two pathway forming walls 82 and 82a move toward the rotational shafts 40 and 40a and thus fluid pathways are blocked, the oil can return back through the fluid slots 77 and 79.

Referring to FIGS. 2, 3 and 4, a high pressure fluid flows into the second pressurization chamber 25 through the first fluid pathway hole 76, and the fluid contained in the second pressurization chamber 25 flows into the projection member accommodation grooves 56 and 56a of the two rotors 50 and 50a through the second fluid pathway holes 78 and 78a. Since the configuration and operation of the first side plate 70 placed between the operating chamber 23 and the first pressurization chamber 21 in FIG. 2 are the same as the second side plate 70a, a detailed description thereof will be omitted. Now, the operation of the first embodiment of the present invention will be explained in detail with reference to FIGS. 1 and 3. When the upper rotational shaft 40 is rotated in a counterclockwise direction by the external driving motor, the lower rotational shaft 40a coupled thereto through the gears 401 and 401a is simultaneously rotated in a clockwise direction in the first pressurization chamber 21. At this time, the upper rotor 50 fixed to the upper rotational shaft 40 is rotated in the counterclockwise direction and the lower rotor 50a fixed to the lower rotational shaft 40a is rotated in the clockwise direction. When the two rotors 50 and 50a are rotated, the projection members 52 and 52a protrude radially outward by means of centrifugal force and the ends of the projection members come into contact with the inner surfaces of the pathway forming walls 82 and 82a. In such a state, a fluid sucked into the rotation chamber 33 through the inflow pipe 34 is transferred to the opposite side through pathways 501 and 501a formed between the inner surfaces of the pathway forming walls 82 and 82a and the outer surfaces of the main bodies 52 and 52a of the rotors 50 and 50a. The transferred fluid is discharged through the discharge pipe 36. The discharged fluid is introduced into the upper pressurization chamber 311 and the lower pressurization chamber 351 through the connection pipes 361 and 362. Therefore, the pressure of the discharged fluid is simultaneously transmitted to the upper pressurization chamber 311 and the lower pressurization chamber 351.

At this time, the high pressure fluid on the discharge side is introduced into the first and second pressurization chambers 21 and 25 through the first fluid pathway holes

76 of the first and second side plates 70 and 70a. The introduced fluid pushes the first and second side plates 70 and 70a toward the rotation chamber 33 so as to prevent the leakage of the fluid contained in the rotation chamber 33. Further, the high pressure fluid in the first and second pressurization chambers 21 and 25 is introduced into the respective projection member accommodation grooves 56 and 56a of the upper and lower rotors 50 and 50a through the second fluid pathway holes 78 and 78a. The introduced fluid pushes the projection members 52 and 52a radially outward to come into strong contact with the pathway forming walls 82 and 82a so that the fluid can be smoothly transferred from the suction side to the discharge side. Referring to FIG. 3, when the pressure of the fluid on the discharge side is increased, the pressure of the upper pressure regulation chamber 31 and the lower pressure regulation chamber 35 is also simultaneously increased and thus the pressure plates 84 and 84a are pushed with greater force. Therefore, the two pressure plates 84 and 84a overcome the elastic forces of the coil springs 99 and 99a and are moved toward the rotation chamber 33. At this time, the two pathway forming walls 82 and

82a are simultaneously moved closer to the rotors 50 and 50a and thus the distances between the inner surfaces of the curved portions 821 and 821a of the pathway forming walls 82 and 82a and side surfaces of the rotors 50 and 50a are shortened. Accordingly, the widths of the fluid pathways 501 and 501a are decreased. Consequently, the discharge volume of the fluid is reduced. At this time, the oil contained in the projection member accommodation grooves 56 and 56a that accommodate the retracted projection members 52 and 52a is transferred to other portions through the circular grooves 789 formed in the side plate 70a, and thus, the corresponding amount of oil escapes outside through the second fluid pathway holes 78 and 78a. At this time, when the pathway forming walls 82 and 82a are further moved and thus middle points of the curved portions 821 and 821a come into contact with the rotors 50 and 50a, passage of the fluid is not allowed. In this case, the fluid that is being transferred on the suction side is returned back through the slots 77 and 79. If the pressure on the discharge side is reduced, the pressure exerted on the pressure plates 84 and 84a is also reduced. Consequently, the pathway forming walls 82 and 82a are moved away from the rotors 50 and 50a by means of the forces of the coil springs 99 and 99a. If so, the distances between the inner surfaces of the curved portions 821 and 821a of the pathway forming walls 82 and 82a and the side surfaces of the rotors 50 and 50a are increased and thus the widths of the fluid pathways 501 and 501a are increased. Accordingly, the discharge volume is increased again.

FIG. 5 is a sectional view of an operating chamber of a pump according to a second embodiment of the present invention. Since the configuration and operation of other parts of the pump 10a except rotors 50b and 50c are the same as the first embodiment, only the configuration of the rotors 50b and 50c will be described in detail with reference to FIGS. 5 and 6.

Referring to FIG. 6, the rotor 50b comprises a cylindrical main body 54b, four projection members 52b accommodated in the main body 54b, and escape prevention members 51 for preventing the projection members 52b from escaping from the main body 54b. The main body 54b includes four projection member accommodation grooves 56b radially formed at an angle of 90 degrees between adjacent ones, and intermediate grooves 58b formed between the respective projection member accommodation grooves 56b. Each of the projection member accommodation grooves 56b includes a semicircular bottom 561b and two flat sidewalls 562b extending from both ends of the semicircular bottom 561b to side surfaces of the main body 54b. The distance between the two sidewalls 562b is sufficient to cause one of the projection members 52b that will be described later to be inserted thereinto and moved therein. Coupling grooves 53 into which the escape prevention members 51 to be described later are inserted are provided at both ends of each of the projection member accommodation grooves 56b. Each of the coupling grooves 53 includes a flat bottom 531, flat side surfaces 532 extending vertically from both ends of the bottom 531, and catching steps

533 that are bent at distal ends of the side surfaces 532 perpendicularly toward the interior of the groove and extend a short distance. Each of the intermediate grooves 58b is semicircular and sized such that one of the projection members 52b to be described later can be tightly inserted thereinto. Each of the projection members 52b is cylindrical and includes coupling portions 521b of a circular cross-section at both ends thereof, which are formed in such a manner that an outer surface of the projection member is depressed radially inward and then extends. The coupling portions 521b are coupled with the escape prevention members 51 that will be described later. Each of the escape prevention member 51 includes a semicircular, curved portion 511, two straight portions 512 extending linearly from both ends of the curved portion 511, and catching steps 513 that are bent perpendicularly and outwardly at distal ends of the straight portions 512 and extend a short distance. The distance between the two straight portions 512 is determined such that the coupling portion 521b of the projection member 52b can be inserted therebetween. The distance between both distal ends of the two catching steps 513 is slightly smaller than the width of the coupling groove 53 of the projection member accommodation groove 56b. The escape prevention member 51 is inserted such that both distal ends of the two catching steps 513 face the side surfaces 532 of the coupling groove 53 of the projection member accommodation groove 56b. The escape prevention member 51 inserted into the projection member accommodation groove 56b in such a manner can move in a radial direction with regard to the rotor 50b but prevents the projection member 52b from escaping from the projection member accommodation groove since the catching steps 513 of the escape prevention member 51 are caught by the catching steps 533 of the coupling groove 53. FIG. 7 is a sectional view of an operating chamber of a pump according to a third embodiment of the present invention. The pump 10b comprises a housing 20d, two rotational shafts 40d and 40e, two rotors 50d and 50e, two pathway forming walls 82d and 82e, two moving devices 210 and 210a, and two side plates 70d (only one is shown in the figure) for pressurizing the operating chamber on both sides. The housing 20d includes a bottom 22d and a top wall 24d that face each other in an upward and downward direction, and two opposite sidewalls 26d and 30d. An inflow pipe 34d and a discharge pipe 36d are provided in the two sidewalls 26d and 30d, respectively. The two rotors 50d and 50e respectively coupled to the two rotational shafts 40d and 40e and the pathway forming walls 82d and 82e respectively surrounding the rotors 50d and 50e are provided in the operating chamber. Since their configurations are the same as the first embodiment, a detailed description thereof will be omitted.

The moving devices 210 and 210a are coupled to the pathway forming walls 82d and 82e, respectively. The moving devices 210 and 210a include moving shafts 211 and 211a in the form of cylindrical rods penetrating the top wall 24d and the bottom

22d of the housing 20d, respectively, and handles 212 and 212a coupled to outer ends of the moving shafts 211 and 211a, respectively. Inner ends of the moving shafts 211 and 211a are fixed to curved portions 821d and 821e of the pathway forming walls 82d and 82e, respectively. Threads are formed on the moving shafts 211 and 211a, and thus, turning of the handles 212 and 212a causes the moving shafts 211 and 211a to be linearly moved. Thus, the pathway forming walls 82d and 82e that are in contact with the ends of the moving shafts 211 and 211a are simultaneously moved to change the discharge volume of oil.

FIG.8 is a section view of an operating chamber of a pump according to a fourth embodiment of the present invention. Referring to FIG. 8, two pressure compensators 110 and 110a that are in contact with pathway forming walls 82f and 82g are provided in a top wall 24f and a bottom 22f, respectively. The pressure compensators 110 and 110a communicate with a discharge pipe 36f through connection pipes 510 and 510a. The other configurations are the same as the third embodiment shown in FIG. 7. The pressure compensators 110 and 110a include cylinders 111 and Ilia, and pistons 112 and 112a disposed within the cylinders ill and Ilia, respectively. One ends of the cylinders 111 and Ilia are fixed to the top wall 24f and the bottom 22f and then connected to the connection pipes 510 and 510a, respectively. At the other ends of the cylinders, extension shafts 113 and 113a extending from the pistons 112 and 112a protrude outside the cylinders 111 and Ilia, respectively. Ends of the extension shafts 113 and 113a are fixed to the pathway forming walls 82f and 82g, respectively.

With the aforementioned configuration, the pressure on the discharge side is transmitted to the cylinders 111 and Ilia through the connection pipes 510 and 510a. This pressure is exerted on the pistons 112 and 112a in the cylinders 111 and Ilia to move the pathway forming walls 82f and 82g. If the pressure on the discharge side is increased, the pistons 112 and 112a are moved toward the rotors 50f and 50g and the pathway forming walls 82f and 82g are accordingly moved toward the rotors 50f and 50g. Thus, the discharge volume is reduced. On the other hand, if the pressure on the discharge side is decreased, the pistons 112 and 112a are moved away from the rotors 50f and 50g and the pathway forming walls 82f and 82g are accordingly moved away from the rotors 50f and 50g. Thus, the discharge volume is increased.

FIG. 9 is a sectional view of an operating chamber of a motor according to a fifth embodiment of the present invention. Referring to FIG. 9, in the operating chamber of the motor 12, coil springs 569 are provided in projection member accommodation grooves 56h, and coil springs 99h and 99i are provided between two pressure plates 84h and 84i and a top wall 24h and a bottom 22h, respectively. The fluid on the suction side is introduced into spaces between the pressure plates 84h and 84i and first and second separation walls 27h and 29h so that pressurization chambers 311h and 351h are provided between the pressure plates 84h and 84i and the first and second separation walls 27h and 29h, respectively. The other configurations are the same as the operating chamber of the first embodiment. Projection members 52h are urged to protrude outside of a rotor 50h by means of the coil springs 569 in the projection member accommodation grooves 56h. The high pressure fluid is introduced through an inflow pipe 34h provided at the left side of a rotation chamber 33h to rotate two rotors 52h and 52i (the upper rotor 52h is rotated in the clockwise direction, while the lower rotor 52i is rotated in the counterclockwise direction) and flows out through a discharge pipe 36h on the opposite side. If an external load is increased, the rotational speed of the rotors 50h and 50i is lowered, and accordingly, pressure in the inflow pipe 34h is increased and the pressure in pressurization chambers 31 In and 35 lh is simultaneously increased. Thus, the pathway forming walls 82h and 82i are moved away from the rotors 50h and 50i, rotational force becomes greater, and the rotational speed becomes smaller.

FIG. 10 is a sectional view of an operating chamber of a motor according to a sixth embodiment of the present invention. Referring to FIG. 10, the operating chamber of the motor 12a includes coil springs 99k and 99j provided between a bottom 22j and a lower pathway forming wall 82k and between a top wall 24j and an upper pathway forming wall 82j, respectively, and air pathway holes 901 and 901b provided in the top wall 24j and the bottom 22j. The other configurations of rotors 50j and 50k and the pathway forming walls 82j and 82k except the above configuration are the same as the fifth embodiment shown in FIG. 9. If an external load is increased, the rotational speed of the rotors 50j and 50k is lowered, and accordingly, pressure in an inflow pipe 34j is increased and the pressure in a rotation chamber 33j is simultaneously increased. Thus, the pathway forming walls 82j and 82k are moved away from the rotors 50j and 50k, rotational force becomes greater, and the rotational speed becomes smaller.

FIG. 11 is a sectional view of an operating chamber of a motor according to a seventh embodiment of the present invention. Referring to FIG. 11, the operating chamber of the motor 12b includes two pressure compensators 110m and HOn provided between a bottom 22m and a lower pathway forming wall 82n and between a top wall

24m and an upper pathway forming wall 82m, respectively. The other configurations are the same as the sixth embodiment shown in FIG. 10. The upper pressure compensator 110m includes a cylinder 111m and a piston 112m disposed within the cylinder 111m. One end of the cylinder 111m is fixed to a top wall 24m. At the other end of the cylinder, an extension shaft 113m extending from the piston 112m protrudes outside the cylinder 111m. An end of the extension shaft 113m is fixed to the upper pathway forming wall 82m. Since the lower pressure compensator llOn is the same as the upper pressure compensator 110m in view of their constitutions, a detailed description thereof will be omitted. In such a configuration, if an external load is increased, the rotational speed of rotors 50m and 50n is lowered, and accordingly, the pressure in an inflow pipe 34m is increased and the pressure in a rotation chamber 33m is simultaneously increased. Thus, the pathway forming walls 82m and 82n are moved away from the rotors 50m and 50n, rotational force becomes greater, and the rotational speed becomes smaller. FIG.12 is a sectional view of an operating chamber of a pump according to an eighth embodiment of the present invention. Referring to FIG. 12, the pump lOp comprises a housing 20p, two rotational shafts 40p, two rotors 50p, and two side plates 70p (only one is shown in the figure) for pressurizing the operating chamber on both sides. The identical rotors 50p with a generally circular cross-section are fixed to the two rotational shafts 40p, respectively. Each of the rotors 50p includes a main body 54p of which the center is fixed to the relevant rotational shaft 40p, and four cylindrical projection members 52p that are coupled to the main body 54p and come into contact with an inner surface of the housing 20p. Four projection member accommodation grooves 571 provided at an angle of 90 degrees between adjacent grooves, and four intermediate grooves 58p positioned between the two adjacent grooves 571 are formed on the main body 54p. The shape and size of each of the accommodation grooves 571 is determined to accommodate generally half of one of the cylindrical projection members 52p. Fluid accommodation members 572 for accommodating oil are fixed to bottoms of the accommodation grooves 571. Each of the fluid accommodation members 572 includes a flat base 573, and two sidewalls 574 extending from both sides of the base 573. Distal ends of the sidewalls 574 define an opening that communicates with the accommodation grooves 571. However, the openings of the fluid accommodation members 572 are closed by the projection members 52p accommodated in the accommodation grooves 571. Packing 575 is fitted into the distal ends of the sidewalls 574 of each of the fluid accommodation members 572, which are in close contact with the relevant contact member 52p, so as to prevent the leakage of oil. The shape and size of each of the intermediate grooves 58p positioned between the adjacent accommodation grooves 571 are determined to accommodate a protruding portion of one of the projection members 52p. The rotors 50p are orientated such that they can be rotated together while the projection members of one of the rotors are engaged with the accommodation grooves of the other of the rotors.

The shape of the housing 20p is determined such that an inner surface thereof can come into contact with protruding ends of the projection members 52p of the rotating rotors 50p. That is, as shown in the figure, the housing 20p takes the shape of a combination of two housing pieces with a generally circular cross-section that surround the two rotors 50p. Each of the two side plates 70p (only one is shown in the figure) for pressurizing the operating chamber on both sides includes a first fluid pathway hole 76p communicating with the discharge side, and a second fluid pathway hole 78p communicating with the interiors of the fluid accommodation members 572 of the rotors 50p. The high pressure fluid flows to the backs of the side plates 70p through the first fluid pathway hole 76p and pushes the side plates 70p toward the operating chamber. Further, the fluid that pushes the side plates 70p enters the fluid accommodation members 572 through the second fluid pathway hole 78p and pushes the projection members 52p against the housing 20p.

The pump with such a configuration is a constant discharge volume type in which the discharge volume does not vary and the oil introduced through the suction side is transferred along the inner surface of the housing by means of rotation of the rotors and then discharged outside of the pump through the discharge side. FIG. 13 is a sectional view of an operating chamber of a pump according to a ninth embodiment of the present invention. Referring to FIG. 13, the pump lOr comprises a housing 20r, two rotational shafts 40r, two rotors 50r, and two side plates 70r (only one is shown in the figure) for pressurizing the operating chamber on both sides. The identical rotors 50r with a generally circular cross-section are fixed to the two rotational shafts 40r, respectively. Each of the rotors 50p includes a main body 54r of which the center is fixed to the relevant rotational shaft 40r, and two cylindrical projection members 52r that are coupled to the main body 54r and come into contact with an inner surface of the housing 20r. Two projection member accommodation grooves 571r provided at an angle of 180 degrees therebetween, and two intermediate grooves 58r positioned between the two grooves 571r are formed on the main body 54r. The shape and size of each of the accommodation grooves 57 lr are determined to accommodate generally half of one of the cylindrical projection members 52r. Contact surfaces of the projection members 52r are coupled and fixed to the accommodation grooves 571r by means of keys 581r so that the projection members 52r do not escape from the accommodation grooves 571r. The shape and size of each of the intermediate grooves 58r are determined to accommodate a protruding portion of one of the projection members 52r. The rotors 50r are orientated such that they can be rotated together while the projection members of one of the rotors are engaged with the accommodation grooves of the other of the rotors.

Upper and lower portions of the housing 20r take the shape of a semicircle to be in contact with ends of the respective projection members 52r, and right and left portions of the housing are flat. With such a configuration, the fluid introduced through the right portion is transferred to the left discharge side by means of rotation of the rotors and then discharged outside of the pump.

FIG. 14 is a sectional view of an operating chamber of a pump according to a tenth embodiment of the present invention. Referring to FIG. 14, the pump 10s comprises two rotational shafts 40s disposed one above the other, rotors 50s and 50t coupled to the respective rotational shafts 40s, a housing 20s surrounding the rotors 50s, and side plates 70s (only one is shown in the figure) for pressurizing the operating chamber on both sides. The upper rotor 50s of the two rotors includes a main body 54s of which the center is coupled to the rotational shaft 40s, and cylindrical projection members 52s that are coupled to the main body 54s and come into contact with an inner surface of the housing 20s. Three projection member accommodation grooves 56s provided equiangularly to accommodate the projection members 52s are formed on the main body 54s. The accommodation grooves 56s are rounded to come into close contact with the projection members 52s. Fluid accommodation grooves 567s for accommodating oil are provided in bottoms of the accommodation grooves 56s. Packings 575s are provided on contact surfaces of the accommodation grooves 56s, which are in contact with the projection members 52s, so as to prevent the leakage of oil to the outside. The lower rotor 50t of the two rotors is provided with auxiliary grooves 58t to accommodate protruding portions of the projection members 52p. The housing 20s is configured such that it is in contact with an outer surface of the lower rotor 50t and with the projection members 52 of the upper rotor 50s. FIG. 15 is a sectional view of an operating chamber of a pump according to an eleventh embodiment of the present invention. Referring to FIG. 15, the pump lOu comprises a housing 20u, two rotors 50u disposed one above the other, two pathway forming walls 82u disposed one above the other, two side plates 70u (only one is shown in the figure) for pressurizing the operating chamber on both sides, and a pressure regulating unit lOOu disposed at the right side of the housing 20u. Since the configurations of the rotors 50u, the pathway forming walls 82u and the side plates 70u are the same as described in connection with FIGS. 5 and 6, a detailed description thereof will be omitted.

The operating chamber is divided into a rotation chamber interposed between the two pathway forming walls 82u, an upper pressurization chamber 31u placed above the upper pathway forming wall 82u, and a lower pressurization chamber 35u placed below the lower pathway forming wall 82u. The two pathway forming walls 82u are not fixed but move in an upward and downward direction. However, the pathway forming walls 82u are prevented from being moved unnecessarily away from the rotors 50u by means of supports 225u and 245u provided on a bottom 22u and a top wall 24u of the housing 20u, respectively. That is, the pathway forming walls 82u are prevented from being separated from the projection members 52u by means of the supports 225u and 245u.

The pressure regulating unit lOOu is provided at an upper right portion of the housing 20u. The pressure regulating unit lOOu includes a lower low-pressure chamber 98u and an upper high-pressure chamber 97u. The low-pressure chamber 98u and the high-pressure chamber 97u communicate with each other through a connection pathway 96u. The connection pathway 96u communicates with the upper pressurization chamber 31u and the lower pressurization chamber 35u. Further, the low-pressure chamber 98u communicates with an inflow pipe 34u. A bellows 98 lu is installed in the low-pressure chamber 98u. Although not shown in the figure, a coil spring is included in the bellows 981u. A conical valve 982u is provided at one end of the bellows 98 lu to open and close the connection pathway 96u that is connected to the high-pressure chamber 97u. The opposite end of the bellows is fixed to a wall surface. The length of the bellows 981u varies according to the pressure in the low-pressure chamber 98u. That is, if the pressure in the low-pressure chamber 98u is higher than a predetermined reference pressure, the length of the bellows 98 lu is shortened since the pressure overcomes the elastic force of the coil spring in the bellows 98 lu. On the contrary, if the pressure in the low-pressure chamber 98u is lower than the predetermined reference pressure, the length of the bellows 981u is lengthened by means of the elastic force of the coil spring in the bellows 98 lu. A beginning portion of the connection pathway 96u in the low-pressure chamber 98u is formed slantingly to correspond to the shape of the conical valve 982u. Furthermore, a spherical valve 97 lu is installed at the other beginning portion of the connection pathway 96u in the high-pressure chamber 97u. The spherical valve 971u is coupled to the conical valve

982u in the low-pressure chamber 98u through a connection rod 964u that passes through the connection pathway 96u. When the conical valve 982u closes an inlet of the connection pathway 96u on the side of the low-pressure chamber 98u, the spherical valve 971u opens the other inlet of the connection pathway 96u on the side of the high- pressure chamber 97u. On the contrary, when the spherical valve 971u closes the inlet of the connection pathway 96u on the side of the high-pressure chamber 97u, the conical valve 982u opens the inlet of the connection pathway 96u on the side of the low-pressure chamber 98u.

Now, the operation of this embodiment will be described in detail with reference to FIGS. 15 and 16. The low pressure fluid introduced into the rotation chamber through inflow pipe 34u is compressed while being transferred to the opposite side along the pathway forming walls 82u by means of rotation of the rotors 50u. The high pressure fluid compressed in such a manner flows out through a discharge pipe 36u. If the pressure of the sucked fluid becomes larger than a reference value, the bellows 98 lu in the low-pressure chamber 98u of the pressure regulating unit 99u that is subjected to the pressure is contracted. If the bellows 98 lu is contracted, the conical valve 982u in the low-pressure chamber 98u is opened and the spherical valve 971u in the high-pressure chamber 97u is simultaneously closed, as shown in FIG. 15. In such a state, the upper and lower pressurization chambers 31u and 35u communicate with the low-pressure chamber 98u, and thus, the pressure in the upper and lower pressurization chambers 31u and 35u drops to the same pressure as the low-pressure chamber 98u. Then, the pathway forming walls 82u are moved away from the rotors 50u, and thus, the amount of fluid transferred is increased. The opposite case is shown in FIG. 16. If the pressure of the sucked fluid becomes lower than the reference value, the bellows 981u in the low-pressure chamber 98u that is subjected to the pressure is extended. If the bellows 98 lu is extended, the conical valve 982u in the low-pressure chamber 98u is closed and the spherical valve 97 lu in the high-pressure chamber 97u is simultaneously opened, as shown in FIG. 16. In such a state, the upper and lower pressurization chambers 31u and 35u communicate with the high-pressure chamber 97u, and thus, the pressure in the upper and lower pressurization chambers 31u and 35u is increased.

Although not shown in the figure, the two pathway forming walls are moved toward the rotors and thus the amount of fluid transferred is reduced.

The pump constructed as above can be used in a compressor for an air conditioner of a car. That is, if stronger cooling is needed (i.e., the pressure of a sucked refrigerant is high), the amount of refrigerant discharged can be increased to make the cooling capability high. On the contrary, if weaker cooling is needed (i.e., the pressure of a sucked refrigerant is low), the amount of refrigerant discharged can be decreased to make the cooling capability low.

FIGS. 17 to 19 are views of a twelfth embodiment of the present invention. Referring to FIG. 17, a pump lOv comprises a housing 20v, two rotational shafts 40v and 41v, six rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6, and two side plates 70v and 71v. The housing 20v includes a sidewall 25v and first and second end walls 28v and 32v for closing front and rear faces defined by the sidewall 25v. Referring to FIGS. 17 and 18, the sidewall 25v is constructed such that an inner surface thereof completely surrounds the respective rotors contained therein and comes into close contact with projection members 52v provided on the rotors. The sidewall 25v include an upper wall 252v surrounding upper rotors and a lower wall 25 lv surrounding lower rotors. Portions where the upper wall 252v and the lower wall 251v are joined are indented inward. The shape of the sidewall 25v is to lengthen regions where the projection members of the rotors come into close contact with the inner surface of the sidewall 25v, to the maximum extent. With such a configuration, upon rotation of the rotors, both the foremost among the leading projection members 52v and the last among the following projection members 52v come into close contact with the inner surface of the sidewall 25v. Thus, the fluid is compressed smoothly. In the present embodiment, the angle a between the foremost among the leading projection members

52v and the last among following projection members 52v is 255 degrees. This is because the phase difference between adjacent rotors coupled to each of the rotational shafts is 15 degrees. This will be explained in detail later. That is, when the central angles of circular arcs defined by the upper wall 252v and the lower wall 25 lv of the sidewall 25v are 255 degrees or more, the fluid can be smoothly transferred.

Referring to FIG. 17, first and second side plates 70v and 71v are provided in the housing 20v to be parallel to the end walls 28v and 32v of the housing 20v. The first side plate 70v is located closer to the first end wall 28v, and the second side plates 71v is located closer to the second end wall 32v. The interior of the housing 20v is divided into three spaces by means of the first and second side plates 70v and 71v. An intermediate space among the spaces (i.e., space between the first and second side plates 70v and 71v) is an operating chamber 23 v into/from which the fluid is introduced/discharged by means of the six rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6. The space between the first end wall 28v and the first side plate 70v and the space between the second end wall 32v and the second side plate 71v are first and second pressurization chambers 21v and 26v, respectively. The high pressure fluid introduced from the operating chamber 23v into the first and second pressurization chambers pushes the first and second side plates 70v and 71v toward the operating chamber 23v. Referring to FIG. 18, an inflow pipe 34v and a discharge pipe 36v communicating with the operating chamber 23v are connected to central portions of both sides of the housing sidewall 25 v.

Referring to FIGS. 17 and 18, the first and second rotational shafts 40v and 41v run parallel to each other one above the other between the first and second end walls 28v and 32v of the housing 20v. The both rotational shafts 40v and 41v sequentially pass through the first pressurization chamber 21v, the operating chamber 23v and the second pressurization chamber 26v. The upper rotational shaft 40v of the two rotational shafts 40v and 41v passes through the first end wall 28v, extends outside of the housing, and is then connected to a driving motor, not shown, to drive the pump lOv. The rotational shafts 40v and 41v are rotatably coupled to the first and second end walls 28v and 32v while being supported by ball bearings 37v (only ball bearings provided in the first end wall 28v are shown in FIG. 17). The rotational shafts 40v and 41v have gears 401v and 402v that are engaged with each other in the first pressurization chamber 21 v, respectively. The gears 401v and 402v are identical gears and cause the rotational speeds and rotating angles of the rotational shafts 40v and 41v to correspond to each other. The first and second rotational shafts 40v and 41v penetrate through the centers of the respective six rotors and are coupled thereto to rotate together therewith in the operating chamber 23v.

Referring to FIG. 19, a region of an outer surface of each of the rotational shafts 40v and 41v to which -the respective rotors are coupled is formed with plural sawteeth to provide a spline (or serration). The splines are fitted into and coupled to shaft holes 509v and 499v formed in the centers of the rotors. Inner surfaces of the shaft holes 509v and 499v are formed with plural complementary sawteeth fittingly engaged with the sawteeth formed on the rotational shafts 40v and 41v. Threads 403v and 411v are formed in regions at which formation of the sawteeth terminates. Nuts 404v and 412v are fastened onto the threads 403v and 411v so that the six rotors coupled to the respective rotational shafts 40v and 41v are in close contact with one another. The number of sawteeth formed on each of the rotational shafts 40v and 41v is identical with that of sawteeth formed in each of the shaft holes 509v and 499v of the six rotors coupled thereto. The angle between adjacent sawteeth is determined according to the phase difference between the adjacent rotors coupled to each of the rotational shafts.

This will be described later.

Referring to FIG. 17, first, second, third, fourth, fifth and sixth rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 are arranged in order from the first side plate 70v in the operating chamber 23v. Referring to FIGS. 17 to 19, each of the rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 comprises first and second rotors 50v and 49v that are engaged with each other to rotate together. Since there are six rotor pairs, there are also six first rotors 50v and six second rotors 49v. The six first rotors 50v have an identical configuration and are coupled to the first rotational shaft 40v. The six second rotors 49v have an identical configuration and are coupled to the second rotational shaft 41 v. Further, the first and second rotors 50v and 49v also have an identical configuration. Thus, all twelve of the rotors provided in the operating chamber 23v have an identical configuration.

As for the rotors, only the first rotor 50v of the first rotor pair 5v-l will be representatively explained since the twelve rotors have an identical configuration. Referring to FIGS. 18 and 19, the rotor 50v includes a main body 54v and two cylindrical projection members 52v. The main body 54v is constructed in such a manner that two coupling grooves 541v to which the projection members 52v will be coupled, and two intermediate accommodation grooves 58v provided between the two coupling grooves 54 lv are formed on an outer surface of a cylindrical member. The two coupling grooves 541v take the shape of an arc and are provided equiangularly (i.e., at an angular interval of 180 degrees since there are the two coupling grooves). The cylindrical projection members 52v are fixed into the respective coupling grooves 541 v by means of keys 581v. The accommodation grooves 58v take the form of an arc and are provided at middle positions between the coupling grooves 541v. The shaft hole 509v into which the rotational shaft 40v is inserted is formed at the center of the main body 54v. The plural sawteeth are provided in the inner surface of the shaft hole 509v so as to be fittingly engaged with the sawteeth provided on the outer surface of the rotational shaft 40v. The number of sawteeth is determined such that the six first rotors 50v to be coupled to the rotational shaft 40v are fitted over the rotational shaft 40v with different phase differences. Consequently, twenty four sawteeth are formed.

This will be explained in detail later.

The first and second rotors 50v and 49v of each of the rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 are arranged such that the projection member 52v is accommodated in and engaged with the accommodation groove 58v at their contact position. Further, the respective rotors of the six rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-

5 and 5v-6 are coupled to the first and second rotational shafts 40v and 41v such that they are engaged with each other at different timings. To this end, the six first rotors 50v coupled to the first rotational shaft 40v have phase differences rotated sequentially by 15 degrees in the clockwise direction from the first rotor 50v of the first rotor pair 5v-l to the first rotor 50v of the sixth rotor pair 5v-6. Similarly, the six second rotors

49v coupled to the second rotational shaft 41v have phase differences rotated sequentially by 15 degrees in the counterclockwise direction from the second rotor 49v of the first rotor pair 5v-l to the second rotor 49v of the sixth rotor pair 5v-6.

The phase difference of 15 degrees is determined as follows. In order to cause the six rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 to be engaged at different timings, before any one of the six rotor pairs is engaged again, the other five rotor pairs should have already been engaged once. That is, if the phase difference is set to a value (15 degrees) obtained by dividing a rotation angle of the first and second rotors 50v and 49 v for second engagement of any one of the rotor pairs (90 degrees: the projection member is accommodated in and engaged with the accommodation groove whenever the first and second rotors are rotated through 90 degrees) by the number of rotor pairs (six), the respective rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 are engaged sequentially at different timings. In order to cause the six first rotors 50v to be sequentially coupled to the first rotational shaft 40v with the phase difference of 15 degrees between adjacent rotors, twenty four sawteeth are provided in the shaft holes 509v of the six first rotors 50v into which the first rotational shaft 40v is inserted. This causes the angle between the adjacent sawteeth to be 15 degrees so that the six first rotors 50v can be easily coupled to the first rotational shaft 40v with the phase difference of 15 degrees between the adjacent rotors. That is, the number of sawteeth of 24 can be obtained by dividing 360 degrees by the phase difference of 15 degrees.

Those skilled in the art can understand that the number of sawteeth is not limited to 24 but may be multiples of 24. The number of sawteeth of each of the shaft holes 499v provided in the six second rotors 49v is also 24 in the same manner as the first rotors 50v. By constructing the six rotor pairs 5v-l, 5v-2, 5v-3, 5v-4, 5v-5 and 5v-6 in such a way, the six rotor pairs are engaged sequentially at different timings. Thus, vibration and noise can be reduced.

Referring to FIG. 17, the first and second side plates 70v and 71v are constructed such that outer peripheries thereof are in close contact with the inner surface of the sidewall 25v. Referring to FIG. 18, a fluid pathway hole 76v illustrated by a dotted line is formed in the second side plate 71v. The fluid pathway hole 76v is formed near the discharge side of the operating chamber 23v to which the discharge pipe 36v is connected, and communicates with the second pressurization chamber (26v in FIG. 17). The high pressure fluid in the operating chamber 23v flows in the second pressurization chamber (26v in FIG. 17) through fluid pathway hole 76v of the second side plate 71v and pushes the second side plate 71v toward the operating chamber 23v.

The second side plate 71v pushes the operating chamber 23 v and simultaneously prevents the leakage of fluid. Although not shown in the figure, the first side plate 70v is also formed with a fluid pathway hole in the same manner as the second side plate 71v. Similarly, the first side plate 70v pushes the operating chamber 23v and simultaneously prevents the leakage of fluid. Meanwhile, if the projection members

52v are made in the form of a true cylinder, spaces may be produced between a leading projection member 52v and a following projection member 52v, resulting in the leakage of fluid. To prevent this, an end portion (a portion illustrated by a dotted line in FIG. 19) of each of the projection member 52v is partially cut away so that the curvature of a curved surface of the end portion of the projection member 52v corresponds to that of the inner surface of the sidewall 25v. It is preferred that any space through which the fluid leaks out be eliminated.

Now, the operation of the present embodiment will be explained in detail with reference to FIGS. 17 to 19. When the first rotational shaft 40v is rotated in the counterclockwise direction by means of an external driving motor, the second rotational shaft 41v coupled to the first rotational shaft through the gears 40 lv and 402v is simultaneously rotated at the same speed in the clockwise direction. At this time, the six first rotors 50v fixed to the first rotational shaft 40v are rotated in the counterclockwise direction, whereas the six second rotors 49v fixed to the second rotational shaft 41v are rotated in the clockwise direction. As all the twelve first and second rotors 50v and 49v are rotated, the projection members 52v are also moved while being in contact with the inner surfaces of curved portions 253v and 254v of the housing 20v. In this state, fluid introduced into the operating chamber 23v through the inflow pipe 34v is transferred to the opposite side through a fluid transfer pathway formed between the inner surfaces of the curved portions 253 v and 254v of the housing

20v and the outer surfaces of the main bodies of the rotors 50v and 49v. The transferred fluid is discharged through the discharge pipe 36v. At this time, the high pressure fluid on the discharge side is introduced into the first and second pressurization chambers 21v and 26v through the fluid pathway holes 76v of the first and second side plates 70v and 71v. The introduced fluid pushes the first and second side plates 70v and 71v toward the operating chamber 23v and prevents the leakage of the fluid in the operating chamber 23v. Since the respective projection members 52v are distributed evenly in a circumferential direction with the phase differences and the respective rotor pairs are engaged at different timings, it is possible to reduce vibration and noise resulting from the rotation of the rotors.

FIG. 20 is a sectional view showing the interior of an operating chamber with a housing of a fluid pump according to a thirteenth embodiment of the present invention cut perpendicularly to a rotational shaft. Referring to FIG. 20, although not shown in detail in the figure, five rotor pairs are provided. Each of the rotor pairs includes a first rotor 50w coupled to a first rotational shaft 40w and a second rotor 49w coupled to a second rotational shaft 41w. The first rotor 50w coupled to the first rotational shaft 40w includes a main body 54w and four cylindrical projection members 52w. The main body 54w is constructed such that four coupling grooves 541w to which the projection members 52w are coupled are formed on an outer surface of a cylindrical member. The four coupling grooves 541w take the shape of an arc and are provided equiangularly (i.e., at an angular interval of 90 degrees since there are the four coupling grooves). The cylindrical projection members 52w are fixed into the respective coupling grooves 541w by means of keys 581w. Although not shown in detail in the figure, the coupling of the main body 54w and the first rotational shaft 40w is achieved by sawteeth engagement in the same manner as the embodiment shown in FIG. 19. In the second rotor 49w coupled to the second rotational shaft 41w, six accommodation grooves 58w are provided equiangularly (i.e., at an angular interval of 60 degrees since there are the six accommodation grooves) on an outer surface of a cylinder member. Protruding portions of the projection members 52w of the first rotor 50w can enter and escape from the six accommodation grooves 58w. The five rotor pairs each of which includes the first and second rotors 50w and 49w are constructed in the same manner as the twelfth embodiment so that they are engaged at different timings. That is, if phase differences are set to values (18 degrees in case of the first rotor and 12 degrees in case of the second rotor) obtained by dividing rotation angles of the first and second rotors 50w and 49w for second engagement of any one of the rotor pairs (the projection members are accommodated in and engaged with the accommodation grooves whenever the first and second rotors are rotated by 90 and 60 degrees, respectively) by the number of rotor pairs (five), the respective rotor pairs are engaged sequentially at different timings. Although not shown in detail in the figure, in order to cause the five first rotors 50w to be sequentially coupled to the first rotational shaft 40w with the phase difference of 18 degrees between adjacent rotors, twenty sawteeth are provided in shaft holes of the five first rotors 50w into which the first rotational shaft 40w is inserted. This causes the angle between the adjacent sawteeth to be 15 degrees so that the five first rotors 50w can be coupled to the first rotational shaft 40w with the phase difference of 15 degrees between the adjacent rotors. That is, the number of sawteeth of 20 can be obtained by dividing 360 degrees by the phase difference of 18 degrees. The number of sawteeth formed in shaft holes of the five second rotors 49w is determined in the same manner as described above. That is, the number of sawteeth can be determined as 30 obtained by dividing 360 degrees by the phase difference of 12 degrees of the second rotors 49w.

The housing 20w is constructed to surround the first rotors 50w and the second rotors 49w. Since the other configurations and operations are the same as the twelfth embodiment, a detailed description thereof will be omitted.

FIGS. 21 to 25 show a fluid pump according to a fourteenth embodiment of the present invention. Referring to FIG. 21, the fluid pump comprises first and second rotational shafts 40x and 41x running parallel to each other, two rotor pairs 5x-l and 5x- 2 each of which includes first and second rotors 50x and 49x, and an intermediate separation plate llx between the two rotor pairs 5x-l and 5x-2. This configuration is almost identical with that shown in FIG. 19 except that there are the two rotor pairs, the intermediate separation plate llx is provided between the two rotor pairs, and three projection members 52x and three accommodation grooves 58x are provided in the first and second rotors 50x and 49x, respectively. A phase difference between the two first rotors 50x coupled to the first rotational shaft 40x is 30 degrees. A phase difference between the two second rotors 49x coupled to the second rotational shaft 41x is also 30 degrees. Further, the numbers of engaging sawteeth formed in the first and second rotors 50x and 49x and on the two rotational shafts 40x and 41x are 12, respectively. The method of determining the phase difference and the number of sawteeth is the same as the twelfth embodiment.

Referring to FIG. 22, the intermediate separation plate llx includes first and second disk- type rotational plates lllx and 112x respectively coupled to the first and second rotational shafts (40x and 41x in FIG. 21), and a frame 113x surrounding the first and second rotational plates lllx and 112x. Shaft holes llllx and 1121x into which the first and second rotational shafts (40x and 41x in FIG. 21) are inserted are formed at the centers of the first and second rotational plates lllx and 112x. Twelve sawteeth are formed in each of the shaft holes llllx and 1121x. The diameter of the first and second rotational plates lllx and 112x is identical with that of the first and second rotors 50x and 49x. The frame 113x includes two upper and lower semicircular, curved portions 1131x, and two straight portions 1132x connecting the curved portions. Inner peripheries of the curved portions 1131x are in contact with outer peripheries of the two rotational plates lllx and 112x. Although not shown in the figure, an outer periphery of the frame 113x is in close contact with an inner surface of a housing. Although not shown in the figure, the inner surface of the housing is configured such that it can be in close contact with the outer periphery of the frame 113x. FIG. 23 shows another embodiment of the intermediate separation plate.

Referring to FIG. 23, the intermediate separation plate lly is configured such that an outer periphery thereof can be in close contact with the inner surface of the housing. The intermediate separation plate lly is provided with two circular, shaft holes 115y and 116y through which the first and second rotational shafts can pass. The interior of the operating chamber of the fluid pump is divided into first and second compression chambers 12 and 13 by means of the intermediate separation plate of FIG. 22 or 23, as illustrated by dotted lines in FIG. 24 or 25. FIG. 24 shows a pump constructed to perform one-stage compression. The first compression chamber 12 and the second compression chamber 13 cannot communicate with each other due to the intermediate separation plate llx. Referring to FIG. 24, an inflow pipe 34x is branched and connected to the fluid pump lOx so that the fluid is introduced into the first and second compression chambers 12 and 13 from the outside of the fluid pump. On the opposite side, a discharge pipe 36x is connected to the fluid pump such that the fluids discharged from the first and second compression chambers 12 and 13 are joined. Referring to FIG. 25, an inflow pipe is connected to the pump lOy such that fluid is introduced into the first compression chamber 12 from the outside of the pump. Fluid discharged from the first compression chamber 12 is introduced again into the second compression chamber 13 through an intermediate connection pipe 35y. The fluid introduced into the second compression chamber 13 is discharged outside of the pump lOy through a discharge pipe 36y. FIG. 26 shows a fluid pump according to a fifteenth embodiment of the present invention, wherein there are shown two rotors 50z that are engaged with each other to rotate together and rotational shafts 40z coupled to the respective rotors 50z. The two rotors 50z have an identical configuration. Each of the rotors 50z includes two projections 52z, and two accommodation grooves 58z that are provided between the two projections 52z and can accommodate relevant projections 52z. A shaft hole 509z into which the rotational shaft 40z is inserted and coupled is provided at the center of each of the rotors 50z. Four coupling projection steps 508z are provided on an inner surface of the shaft hole 509z. Each of the rotors 50z is constructed by stacking plural plate members 510z with the same cross section as the rotor, as shown in the figure. The plate members 510z in the form of the rotor can be easily obtained through press cutting. Thus, the rotor 50z can be mass-produced in a convenient manner. Four guide grooves 408z (only two guide grooves are shown in the figure) are provided on an outer surface of each of the rotational shafts 40z so that the four projection steps 508z formed in each of the coupling shaft holes 509z can be fitted thereinto. Threads 407z are formed at a portion where the guide groove terminates, and a nut 404z is fastened onto the threads so that the plural plate members 510z are not separated from one another. Although FIG. 26 shows that there is no phase difference between the rotors, there may be a phase difference between the rotors. In the aforementioned embodiments, timing gears are used for simultaneously rotating the two rotors. However, the present invention is not limited thereto. Those skilled in the art can understand that the timing gears may not be needed if there are a lot of projection members provided on the rotors.

Although the present invention has been described and illustrated in connection with the preferred embodiments, it will be understood that various modifications, changes and additions can be made thereto without departing from the scope and spirit of the present invention.

Claims

1. A fluid pump, comprising: a housing provided with an inflow pipe and a discharge pipe, a fluid being introduced through the inflow pipe into and discharged through the discharge pipe from the housing; and first and second rotors that are disposed parallel to each other within the housing and rotate about respective rotation axes thereof while being engaged with each other, wherein the first rotor includes a main body that rotates about the rotation axis of the first rotor, and plural cylindrical projection members that are installed on the main body and disposed parallel to the rotation axis of the rotor so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body, the fluid pump further comprises a pathway forming wall partially surrounding the first rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the first rotor and comes into contact with the projection members, and the second rotor includes a main body that rotates about the rotation axis of the second rotor and is provided with grooves into which the protruding portions of the projection members of the first rotor can be inserted.

2. The fluid pump as claimed in claim 1, wherein the second rotor further includes plural cylindrical projection members that are installed on the main body and disposed parallel to the rotation axis of the rotor so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body, the fluid pump further comprises a pathway forming wall partially surrounding the second rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the second rotor and comes into contact with the projection members, and the main body of the first rotor is further provided with grooves into which the protruding portions of the projection members of the second rotor can be inserted.

3. The fluid pump as claimed in claim 1 or 2, wherein the main body of the first or second rotor including the projection members is provided with accommodation grooves, the projection members are installed within the accommodation grooves to protrude from or be retracted into the main body, and the pathway forming wall can be moved toward or far away from the rotation axis of the rotor.

4. The fluid pump as claimed in claim 3, wherein the pathway forming wall is moved by the pressure of the fluid discharged to the rear of the pathway forming wall.

5. The fluid pump as claimed in claim 4, further comprising a moving device for the pathway forming wall, wherein the moving device includes a pressure plate subjected to the pressure of the discharged fluid and connected to the pathway forming wall, and a resilient member for exerting a force on the pressure plate in a direction opposite to the pressure of the fluid.

6. The fluid pump as claimed in claim 4, further comprising a moving device for the pathway forming wall, wherein the moving device includes a cylinder disposed at the rear of the pathway forming wall and a piston that reciprocates within the cylinder and is connected to the pathway forming wall, whereby the pressure of the discharged fluid is transmitted into the cylinder to push the piston.

7. The fluid pump as claimed in claim 3, further comprising a moving rod that protrudes outside of the housing and is connected to the pathway forming wall.

8. The fluid pump as claimed in claim 3, further comprising a pressure regulating unit for controlling the movement of the pathway forming wall, wherein the pressure regulating unit includes a low-pressure chamber containing a bellows-type control valve, a high-pressure chamber communicating with the discharge pipe, and a connection pathway for causing the low- and high-pressure chambers to communicate with each other, and the connection pathway communicates with the rear of the pathway forming wall, the bellows-type control valve is provided to open and close an inlet of the connection pathway on the side of the low-pressure chamber, and the high-pressure chamber is provided with a high-pressure chamber valve connected to the bellows-type control valve to open and close an inlet of the connection pathway on the side of the high-pressure chamber.

9. The fluid pump as claimed in claim 3, wherein the accommodation grooves are provided with narrow portions having a width smaller than that of the projection members so that the projection members can be caught by the narrow portions not to escape from the accommodation grooves.

10. The fluid pump as claimed in claim 3, wherein the rotor includes escape prevention members each of which has one side coupled to the main body to radially protrude from and be retracted into the main body and the other side coupled to one of the projection members, the main body includes grooves each of which receives a portion of one of the escape prevention members and guides the protruding and retracting movement of the relevant escape prevention member, and each of the escape prevention members includes catching steps that are caught by distal ends of the relevant groove.

11. The fluid pump as claimed in claim 1 or 2, further comprising side plates disposed perpendicularly to the rotation axes of the first and second rotors so as to divide the interior of the housing into an operating chamber containing the first and second rotors and pressurization chambers that do not contain the first and second rotors and to pressurize the operating chamber.

12. The fluid pump as claimed in claim 11, wherein each of the side plates includes a first fluid pathway hole through which the high pressure fluid in the operating chamber is introduced into one of the pressurization chambers, second fluid pathway holes through which the fluid in the pressurization chambers is introduced into accommodation grooves of the rotors, and fluid slots formed on a suction side along pathways through which the fluid is transferred.

13. The fluid pump as claimed in claim 12, wherein each of the side plates further includes grooves for causing the accommodation grooves of the main body of each of the rotors to communicate with one another.

14. A fluid motor, comprising: a housing; and first and second rotors that are disposed parallel to each other within the housing and rotate about respective rotation axes thereof while being engaged with each other, wherein the first rotor includes a main body that rotates about the rotation axis of the first rotor, and plural cylindrical projection members that are installed on the main body so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body of the rotor, the fluid pump further comprises a pathway forming wall partially surrounding the first rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the first rotor and comes into contact with the projection members, and the second rotor includes a main body that rotates about the rotation axis of the second rotor and is provided with grooves into which the protruding portions of the projection members of the first rotor can be inserted.

15. The fluid motor as claimed in claim 14, wherein the second rotor further includes plural cylindrical projection members that are installed on the main body and disposed parallel to the rotation axis of the rotor so that at least a portion of each of the projection members protrudes outwardly beyond an outer periphery of the main body, the fluid pump further comprises a pathway forming wall partially surrounding the second rotor in a state where the pathway forming wall is spaced apart from the outer periphery of the main body of the second rotor and comes into contact with the projection members, and the main body of the first rotor is further provided with grooves into which the protruding portions of the projection members of the second rotor can be inserted.

16. The fluid motor as claimed in claim 14 or 15, wherein the main body of the first or second rotor provided with the projection members is formed with accommodation grooves, the projection members are installed within the accommodation grooves to protrude from or be retracted into the main body, resilient members for urging the projection members outwardly are installed in the accommodation grooves, and the pathway forming wall can be moved toward or far away from the rotation axis of the rotor.

17. The fluid motor as claimed in claim 16, wherein the pathway forming wall is moved by the pressure of the fluid discharged to the rear of the pathway forming wall.

18. The fluid motor as claimed in claim 17, further comprising a moving device for the pathway forming wall, wherein the moving device includes a pressure plate subjected to the pressure of the fluid on a high pressure side and connected to the pathway forming wall, and a resilient member for exerting a force on the pressure plate in a direction opposite to the pressure of the fluid.

19. The fluid motor as claimed in claim 16, further comprising a resilient member for urging the pathway forming wall toward the rotation axis of the rotor.

20. The fluid motor as claimed in claim 16, further comprising a moving device for the pathway forming wall, wherein the moving device includes a cylinder disposed at the rear of the pathway forming wall and a piston that reciprocates within the cylinder and is connected to the pathway forming wall.

21. A fluid pump, comprising: a housing provided with an inflow pipe and a discharge pipe, a fluid being introduced through the inflow pipe into and discharged through the discharge pipe from the housing; two rotational shafts that run parallel with each other within the housing and rotate in opposite directions; and rotor pairs each of which includes two rotors that are coupled to the respective shafts and engaged with each other to rotate together, wherein one of the two rotors of each of the rotor pairs includes at least two projections protruding radially, and the other rotor includes accommodation grooves in which the projections can be accommodated, and the rotor pairs are two or more rotor pairs, and rotors on the same rotation axis are coupled to the relevant rotational shaft with different phase differences such that the respective rotor pairs are engaged at different timings.

22. The fluid pump as claimed in claim 21, wherein each of the rotors includes a main body coupled to the relevant rotational shaft, and the projections are formed of cylindrical projection members to be engaged with arcuate coupling grooves provided on an outer surface of the main body.

23. The fluid pump as claimed in claim 21 or 22, wherein the phase difference between adjacent rotors is determined as a value obtained by dividing a rotation angle for second engagement of one of the rotors by the number of rotor pairs.

24. The fluid pump as claimed in claim 23, wherein a passage through which the relevant rotational shaft passes is provided at the center of each of the rotors, and complementary sawteeth are provided on an outer surface of the rotational shaft and an inner surface of the passage of the rotor.

25. The fluid pump as claimed in claim 24, wherein the number of sawteeth is determined as a value obtained by dividing 360 degrees by the phase difference or as multiples of the value.

26. The fluid pump as claimed in any one of claims 21 to 25, wherein a nut is fastened onto each of the rotational shafts so as to cause the rotors coupled to the same rotational shaft to be in close contact with one another.

27. The fluid pump as claimed in any one of claims 21 to 25, further comprising intermediate separation plates for isolating respective rotor pairs from one another, and two or more compression chambers that are separated from one another and contain the respective rotor pairs .

28. The fluid pump as claimed in claim 27, wherein the inflow pipe and the discharge pipe are connected to the compression chambers.

29. The fluid pump as claimed in claim 27, wherein the inflow pipe is connected to any one of the two or more compression chambers, the discharge pipe is connected to another of the compression chambers, and intermediate connection pipes serially connect the respective compression chambers.

30. The fluid pump as claimed in claim 27, wherein each of the intermediate separation plates includes rotational plates coupled to the rotational shafts to rotate together therewith.

31. A fluid pump, comprising: two rotational shafts that run parallel with each other and rotate in opposite directions; and rotor pairs each of which includes two rotors that are coupled to the respective shafts and engaged with each other to rotate together, wherein each of the rotors is formed by stacking plural thin plate members with the same cross section as the rotor.