Rotary pump

Abstract: A rotor drive shaft (12) and a rotor (1A, 1B) are connected in such manner that a rotor shaft (2) integrally extends in a plane surface of the rotor (1A, 1B). A tapped hole (3) with a deep concave shape is provided in a leading end surface of the rotor shaft (2) in the axial direction, and a hollow part (16) is provided in the rotor drive shaft (12) such that its passes therethrough in the axial direction. A headed bolt (15) is inserted in the hollow part (16) of rotor drive shaft (12), the head (15a) thereof being in abutment with an end surface of the rotor drive shaft (12), and a threaded leading end (15b) thereof being screwed in the tapped hole (3) of the rotor shaft (2). The rotor (1A, 1B) is fixed to the rotor drive shaft (12) without using any rotor fastening nut, and the inner side surface of casing cover can be formed with an entirely flat shape, so that the retention of a liquid within the casing is prevented.

Description: Field of the Invention The present invention relates to a rotary pump suitable for transporting liquid foods. Background of the Invention Conventionally, a rotary pump used for transporting liquid foods has such structure that a rotary drive shaft is formed with its leading end in a spline shaft, a spline hole formed through a rotor is engaged with the spline shaft, a pumping chamber in a main rotor casing is entered by teeth of the rotor, a fastening nut of the rotor is engaged and fixed at the end of the rotor drive shaft projected from the rotor, and a casing cover having a concave part that is formed in an inner surface thereof and receives the rotor teeth and the rotor fastening nut in rotatable and loose manner is attached to the main casing. Alternatively EP-A-444941 describes a pump the rotors of which are fastened to hollow shafts by tightening bolts passing therethrough. Summary of the Invention In such a conventional rotary pump, a transported liquid flows in the pumping chamber, enters into the concave part inside the casing cover through a narrow spacing between the rotor and the casing cover, and tends to be retained, once it is trapped therein. Thus, if it is retained there, the food trapped may decay or degenerate, so that it has been generally required to fully disassemble the pump and clean the concave part inside the casing cover and the like after the day's transporting operation is completed. However, reassembly of such pump after disassembly and cleaning is laborsome and time-consuming, and eventually leads to increase product cost. Hence, it is a first object of the invention to provide a rotary pump that allows to form the mutually opposite surfaces of a rotor and a casing cover in an entirely flat shape by fixing the rotor to a rotor drive shaft without using a rotor fastening nut, with the result of eliminating deep bag-like parts such as a concave part within the casing and retention of liquid observed in conventional rotary pumps as described above. In order to achieve the object, the invention presents a rotary pump comprising a rotor having a rotor shaft extending in one of plane surfaces, a rotor drive shaft having a hollow part passing therethrough in the axial direction and a headed long bolt inserted into the hollow part of the rotor drive shaft, wherein the rotor drive shaft and the rotor are rigidly connected by driving a threaded part in its leading end of the long bolt that is inserted through the rotor drive shaft, into a tapped hole formed deeply in an end surface of the rotor shaft in the axial direction. In addition, in the invention, pumping teeth of the rotor are disposed in a pumping chamber of main casing, the long bolt being inserted into the hollow rotor drive shaft that is supported in a gearbox, the threaded part in leading end of the bolt being engaged with the tapped hole of rotor shaft, and the bolt head being turned using a spanner or the like, the rotor is drawn toward the side of rotor drive shaft and fastened. Therefore, the rotor can be rigidly connected with and fastened to the rotor drive shaft in a integral manner with the leading end of rotor drive shaft abutted thereto, thus, such rotor fastening nut as those conventionally used is eliminated, rigidity of connection between the rotor and rotor drive shaft can be significantly increased, and sufficient resistance to high pressure is obtained. Additionally, in removing the rotor, it can be easily removed only by loosening a fastening bolt of the rotor after removing the casing cover. Moreover, because it is not required to provide a fastening bolt for connecting a rotor to a rotor drive shaft through the rotor and fastening it with a fastening nut, as described above, a plane surface on the side of the casing cover opposite to a rotor can be formed in a flat shape, thereby allowing the casing cover to be formed flat along the flat plane surface. Therefore, it is possible to eliminate a deep bag-like part such as concave part in the casing, particularly inside the casing cover, and such retention of liquids as observed in conventional rotary pumps, so that, decaying and quality change of liquid foods due to the retention are reduced, and cleaning effect is remarkably improved. Furthermore according to an embodiment of the invention, with such arrangement that a rotor shaft of rotor is engaged in a hollow part in leading end of a rotor drive shaft, the rotor and the rotor drive shaft can be aligned at a higher precision, and rigidity of connection between the rotor and rotor drive shaft can be significantly enhanced. While the novel features of the invention are set forth particularly in the appended claims, the invention, both as to organization and content, will be better understood and appreciated along with other objects and features thereof, from the following detailed description taken in conjunction with the drawings. Brief Description of the Invention Fig. 1 is a side elevational view of a rotary pump according to the invention, showing a vertically sectioned half thereof. Fig.2 is a partially magnified view of Fig. 1. Fig.3 is an end view of a rotary pump with its casing cover removed. It will be recognized that some or all of the figures are schematic representations for purposes of illustration, and do not necessarily depict the actual relative sizes or locations of.the elements shown. Detailed Description of the Preferred Embodiments Referring now to the drawings showing an embodiment of the invention, Fig. 1 is a sectional view of an entire rotary pump sectioned vertically in half, Fig.2 a partially magnified view. of Fig. 1, and Fig. 3 an end view of a rotary pump with its casing cover removed, where references 1A and 1B depict rotors, a rotor shaft 2 is projecting from either rotor 1A and 1B in the central part of an end surface thereof, a tapped hole 3 is provided in a deeply recessed form in a leading end of the rotor shaft 2 in the axial direction. The rotor 1A, 1B has pumping teeth 4 integrally formed in a circumferential part, and an annular groove 5 in the outer circumference of rotor shaft 2 at its foot. Reference numeral 6 shows a pump casing comprising a main casing 10 that has a pumping chamber 7 formed in a recessed shape on one side end surface so as to accommodate the pumping teeth 4, 4 of the rotor 1A, 1B in rotatable and loose manner, and is provided with an inlet 8 and an outlet 9 in communication with the pumping chamber 7, and a casing cover 11 that is detachably mounted to the main casing 10 while being flush with end surface of the rotors 1A and 1B. Reference numeral 12 shows a rotor drive shaft provided in relation to each of the rotors 1A and 1B, and is supported rotatably and in axially immobile state by a.bearing 14 and the like in a gearbox 13. The drive shaft 12 has a hollow part 16 on its inside, passing therethrough in the axial direction. Reference numeral 15 indicates a rotor fastening bolt inserted in the hollow part 16 of hollow rotor drive shafts 12A, 12B from one end to the other end thereof, and a bolt head 15a is locked by means of a spring washer 17 to the end surface of rotor drive shaft. The hollow part 16 of rotor drive shafts 12 is formed in such manner that the leading end side is increased in diameter, the rotor shaft 2 of rotors 1A, 1B is engaged in a hollow portion 16a of the increased diameter, and a threaded leading part 15b of the rotor fastening bolt 15 is engaged in the tapped hole 3 of the rotor shaft 2, for connecting the rotor drive shafts 12 and rotors 1A, 1B, Numerals 18 and 19 depict sealing members provided in a spacing among the inner surface of rotors 1A, 1B, the outer circumferential surface of rotor shaft 2 and the main casing 10 of the pump casing 6, and the sealing member 18 is engaged in an annular groove 5 in the outer circumference of rotor shaft 2 at its foot. The sealing member 18 is rotated integrally with the. rotor 1A (1B), while the other sealing member 19 is fixed to the main casing 10 incapably of rotation. Therefore, a leading end 19a of the fixed sealing member 19 is formed by a very hard material such as ceramics, while the rotating sealing member 17 at the opposite side thereof is formed by tungsten carbide or the like, and the leading end 19a of fixed sealing member 19 is biased by a spring 19b, and comes in contact with the rotating sealing member 18 so that water tightness between them is maintained. Numeral 20 shows a holder member that holds the sealing members 18, 19 from outside, and is fixed to the side of main casing 10. Additionally, in Fig. 1, numeral 21 shows a transmission shaft rotatably supported in the gearbox 13, and connected with a motor (not shown), and rotation of the transmission shaft 21 is transmitted to one of the rotor drive shafts 12 by means of gears 22, 23, and rotation of said one of the rotor drive shafts 12 is, in turn, transmitted to the other rotor drive shaft 12 by means of the gear 23 and other not shown in such manner that the latter shaft rotates synchronously with the former shaft but in the opposite direction. In order to assemble a rotary pump of such structure, the pumping teeth 3 of rotors 1A, 1B are disposed in the pumping chamber 7 of the main casing 10, and the rotor shafts 2 are engaged in the hollow leading portion 16a of hollow rotor drive shafts 12 that are supported in the gearbox 13. Then, the rotor fastening bolt 15 is inserted in the rotor drive shafts 12 from an end thereof, the threaded leading part 15b thereof is screwed into the tapped hole 3 of the rotor shaft 2, and the rotors 1A, 1B are drawn toward the rotor drive shaft 12 and fastened thereto by rotating and tightening the bolt head 15a using such revolving tool as spanner. By tightening the rotor fastening bolt 15 in such manner, the rotors 1A, 1B are connected integrally with the rotor drive shafts 12 with the leading end surface of rotor drive shafts 12 tightly abutted to the inner end surface 24 of the rotors, specifically to the deep end surface of annular groove 5. In this operation, the inner end surface 24 of rotors 1A, 1B is set in such manner that a minimum spacing is provided for its rotation in relation with the inner end surface of pumping chamber 7. Thus, after the rotors 1A, 1B are connected to the rotor drive shafts 12, the casing cover 11 is attached to the main casing 10 of pump casing 6 such that it is flush along the mounting end surface of main casing 10 and the outer end surface of rotors 1A, 1B. Again, the casing cover 11 assures a minimum spacing for rotation of the rotors in relation to the outer end surfaces of rotors 1A and 1B. Incidentally, in attaching the pump casing 6, the main casing 10 is fixed to the gearbox 13, and the casing cover 11 to the main casing 10, for example, by providing plural through-holes (not shown) in the axial direction in the circumferential part of main casing 10 and casing cover 11, inserting respectively therethrough a long bolt 26 projecting from the side of gearbox 13 in the axial direction, and threadedly fastening the inserted end thereof with a butterfly nut. In a rotary pump assembled in such manner, when both rotors 1A and 1B are driven for synchronous rotation in mutually opposite directions, as shown by an arrow in Fig. 3, by means of both rotor drive shafts 12, the action of pumping teeth 4 rotating respectively in the pumping chamber 7 produces a result that a liquid is introduced from the inlet 8 into the pumping chamber 7, and enforced toward the outlet 9. In the invention, since it is not required to provide a fastening bolt through the rotor for connecting the rotor to the rotor drive shaft, and engage it with a fastening nut, as in prior art, a plane surface part opposite to the rotor in the side of casing cover can be formed in a flat shape, such that the entire inner side surface of casing cover 11 comes to be a flat surface.flush with the outer end surface of rotors 1A, 1B without concave part formed for the rotors 1A and 1B. Thus, no retention of a liquid transported and flowing in the pumping chamber occures in any location. Therefore, inside cleaning of the pumping chamber 7 can be simply and easily performed. Moreover, in the case of removing the rotors 1A, 1B, they can be easily removed only by loosening the rotor fastening bolt 15 after removing the butterfly nut 27 and casing cover 11. In the embodiment, by placing the rotor shaft 2 of rotors 1A, 1B in the hollow leading portion of rotor drive shafts 12, the rotors 1A, 1B and rotor drive shafts 12 can be aligned at higher precision, and rigidity of connection between the rotors 1A, 1B and rotor drive shafts 12 is significantly increased. In addition, the hollow leading portion 16a of rotor drive shaft 12 may be further extended to form an extended portion 16b, and a deep groove portion 5a continuously provided within the annular groove 5, so that they are aligned by tightly fitting the outer circumferential surface of extended portion 16b with the inner circumferential surface of deep groove portion 5a. In such case, the hollow portion 16a and the rotor shaft 2 may be in loose engagement. Although the present invention has been described in terms of the presently preferred embodiments, it is to be understood that such disclosure is not to be interpreted as limiting. Various alterations and modifications will no doubt become apparent to those skilled in the art after having read the above disclosure. Accordingly, it is intended that appended claims be interpreted as covering all alterations and modifications as falling within the scope of the invention.

Claims: A rotary pump comprising at least one rotor (1A, 1B) disposed rotatably in a main casing (10), a rotor drive shaft (12) for driving the rotor (1A, 1B) in rotation and a headed long bolt (15) for connecting the rotor with the rotor drive shaft, wherein a rotor shaft (2) is integrally extended from a plane surface of the rotor (1A, 1B), a tapped hole (3) is provided in a deep recessed shape in a leading end surface of the rotor shaft (2) in the axial direction, a hollow part (16) is formed inside the rotor drive shaft (12) so as to pass therethrough in the axial direction, and the rotor (1A, 1B) is connected with the rotor drive shaft (12) such that the headed bolt (15) is inserted in the hollow part (16) of the rotor drive shaft (12), the head (15a) thereof is in abutment with an end surface of the rotor drive shaft (12), and a threaded leading end (15b) thereof is screwed in the tapped hole (3) of the rotor shaft, wherein the rotor shaft (2) of the rotor (1A, 1B) is engaged in the hollow leading part (16a) of the rotor drive shaft (12), and the hollow leading part (16a) of the rotor drive shaft (12) is inserted and fastened within an annular groove (5, 5a) provided in the rotor (1A, 1B) at a portion facing the rotor drive shaft (12) and exterior of the rotor shaft (2) at its foot so that the rotor (1A, 1B) and the rotor drive shaft (12) are aligned at the outer circumferential surface of the hollow leading part (16a) of the rotor drive shaft (12) and an opposite inner circumferential surface of the annular groove (5, 5a) of the rotor in contact therewith. A rotary pump according to Claim 1, wherein a sealing member (18) is disposed in the annular groove (5) of the rotor (1A, 1B) along said circumferential surface of the groove (5) whereby the hollow leading part (16a) of the rotor drive shaft (12) is fastened within the annular groove (5) of the rotor (1A, 1B) by way of the sealing member (18) so that the rotor (1A, 1B) and the rotor drive shaft (12) are aligned at the outer circumferential surface of the rotor drive shaft (12) and an opposite circumferential surface of the annular groove (5, 5a) of the rotor in contact with the sealing member (18). A rotary pump according to Claim 1 or 2, wherein a flat casing cover (11) which is flush along the other plane surface of the rotor (1A, 1B) is attached to the main casing (10).

Inventors: MORITA KAZUO, YAMAMOTO TOKUJI, MORITA, KAZUO, YAMAMOTO, TOKUJI
Applicants: NAKAKIN CO LTD, NAKAKIN CO., LTD.
Application year: 1993
Main classification: F04C15
IPC codes: F04C2, F04C13, F04C15, F04C14