CN108138766B

CN108138766B - Internal gear pump

Info

Publication number: CN108138766B
Application number: CN201680057233.2A
Authority: CN
Inventors: 浅田一; 服部圭; 伊藤贵之; 赤井洋
Original assignee: NTN Corp
Current assignee: NTN Corp
Priority date: 2015-09-30
Filing date: 2016-09-29
Publication date: 2020-03-31
Anticipated expiration: 2036-09-29
Also published as: DE112016004484T5; CN108138766A; WO2017057533A1; CN110360096A; US20180274539A1

Abstract

Provided is a ring gear pump which can stably ensure the sealing performance between a resin housing and a cover which form a trochoid housing part, can omit a sealing ring at the part, and can stabilize the discharge capacity. A ring gear pump (1) is provided with: a trochoidal portion (4) which accommodates an inner rotor (3) having a plurality of outer teeth, within an outer rotor (2) having a plurality of inner teeth, in a state in which the outer teeth mesh with the inner teeth and are eccentric; a housing (5) formed with a trochoid accommodating recess (5 a); and a cover (6) for closing the recess (5a), wherein the housing (5) is an injection-molded body of a resin composition, the housing (5) and the cover (6) are fixed by bolts, a metal bush (7) is provided in a bolt-fixing hole portion of the housing (5), and in a cross section of a joint portion between the housing (5) and the cover (6), an end surface (7a) of the bush (7) is positioned higher than a bush-forming surface (5e) around the bush of the housing (5) and lower than a sealing surface (5d) around the recess of the housing (5) as viewed from a bottom surface (5c) of the recess (5 a).

Description

Internal gear pump

Technical Field

The present invention relates to an internal gear pump (trochoid pump) for pumping a liquid such as oil, water, or a chemical liquid.

Background

The internal gear pump (trochoid pump) is a pump as follows: the outer rotor and the inner rotor having trochoid tooth shapes are housed in a case in a sealed state, and function to suck and discharge liquid by rotating the inner rotor and the outer rotor fixed to the drive shaft in accordance with the rotation of the drive shaft. As such a pump, recently, a pump having a resin housing has been known as a pump which can be manufactured at low cost by reducing a machining process (see patent document 1).

The structure of the ring gear pump will be described with reference to fig. 4 and 8.

Fig. 4 is a cross-sectional view of a conventional internal gear pump. As shown in fig. 4, the pump 21 is mainly provided with a trochoid portion 24 in which an inner rotor 23 having a plurality of external teeth is accommodated in an annular outer rotor 22 having a plurality of internal teeth. The trochoid portion 24 is rotatably housed in a circular trochoid housing recess 25a, and the trochoid housing recess 25a is formed in a flanged cylindrical case 25. A cover 26 that closes the trochoid accommodating recess 25a is fixed to the housing 25.

The trochoid portion 24 is configured by rotatably accommodating the inner rotor 23 in the outer rotor 22 in a state in which the outer teeth of the inner rotor 23 are meshed with the inner teeth of the outer rotor 22 and are eccentric. Between the separation points where the rotors contact each other, a volume chamber on the suction side and a volume chamber on the discharge side are formed in accordance with the rotational direction of the cycloid portion 24. A drive shaft 29 rotated by a drive source not shown is fixed to the axial center of the inner rotor 23 so as to penetrate therethrough. When the drive shaft 29 rotates and the inner rotor 23 rotates, the outer teeth mesh with the inner teeth of the outer rotor 22, and the outer rotor 22 rotates in the same direction, and the volume is increased by the rotation, and the liquid is sucked from the suction port into the suction-side volume chamber which becomes a negative pressure. The suction-side volume chamber becomes a discharge-side volume chamber whose volume decreases and whose internal pressure increases due to the rotation of the trochoid portion 24, and the liquid sucked in is discharged from the discharge-side volume to the discharge port.

The cover 26 is made of sintered metal, and the case 25 is an injection molded body produced by injection molding using a resin composition. A metal bush 27 is integrated with a bolt fixing hole portion of the housing 25 by composite molding at the time of injection molding, and the housing 25 and the cover 26 are connected and fixed to a fixing plate 30 of the apparatus main body by a bolt 28 inserted through the bush 27. The bush 27 is interposed in the connection fixation of the housing 25 and the cover 26 in order to maintain the connection strength at the connection portion.

A seal ring (O-ring) 31 is attached to a groove 32 formed on the outer periphery of the recess of the housing 25 at the joint surface (mating surface) between the housing 25 and the cover 26. This can seal the trochoid accommodation recess 25a and prevent leakage of liquid from the mating surface between the housing 25 and the cover 26. In the internal gear pump, in order to effectively exhibit the pump function, it is important to stably ensure the sealing property (the sealing property of the trochoid accommodating recess 25 a) at the mating surface between the housing 25 and the cover 26. The material of the seal ring 31 is hydrogenated nitrile rubber (H-NBR type) or the like because it has heat resistance and oil resistance at about-30 to 120 ℃ and can be applied to a scroll compressor of an air conditioner.

Fig. 8 is a cross-sectional view of another conventional internal gear pump. As shown in fig. 8, the pump 61 is mainly configured with a trochoid portion 64 in which an inner rotor 63 having a plurality of external teeth is accommodated in an annular outer rotor 62 having a plurality of internal teeth. The trochoid portion 64 is rotatably housed in a circular trochoid housing recess 65a, and the trochoid housing recess 65a is formed in a flanged cylindrical case 65. A cover 66 that closes the trochoid accommodating recess 65a is fixed to the housing 65.

The trochoid portion 64 is configured by rotatably accommodating the inner rotor 63 in the outer rotor 62 in a state in which the outer teeth of the inner rotor 63 are meshed with the inner teeth of the outer rotor 62 and are eccentric. Between the separation points where the rotors contact each other, the suction-side and discharge-side volume chambers are formed in accordance with the rotational direction of the trochoid portion 64. A drive shaft 69 rotated by a drive source not shown is fixed to the axial center of the inner rotor 63 in a penetrating manner. When the drive shaft 69 rotates to rotate the inner rotor 63, the outer teeth mesh with the inner teeth of the outer rotor 62, and the outer rotor 62 rotates in the same direction, and the volume increases due to the rotation, and the liquid is sucked from the suction port into the suction-side volume chamber which becomes a negative pressure. The suction-side volume chamber becomes a discharge-side volume chamber whose volume decreases and whose internal pressure increases due to the rotation of the trochoid portion 64, and the liquid sucked in is discharged from the discharge-side volume chamber to the discharge port.

The cover 66 is made of sintered metal, and the case 65 is an injection molded body produced by injection molding using a resin composition. The housing 65 and the cover 66 are connected to a fixing plate 70 fixed to the apparatus main body by bolts 68. Further, a seal ring 71 is attached to a groove formed on the outer periphery of the recess of the case 65 at a joint surface (mating surface) between the case 65 and the cover 66. Thereby, the trochoid accommodation recess 65a is sealed, and leakage of liquid from the mating surface between the housing 65 and the cover 66, which is a combination of resin and sintered metal, is prevented.

By using the injection molded body (resin molded body) as the housing 65, machining is not required, and it is economical. The housing 65 is in sliding contact with the outer rotor 62 and the inner rotor 63 on a bottom surface 65c and an inner surface 65b constituting the trochoid accommodation recess 65 a. The inner side surface 65b of the trochoid accommodation recess 65a is an injection-molded part of the resin composition, and therefore has excellent frictional wear characteristics with the outer rotor 62. The bottom surface 65c of the trochoid accommodation recess 65a is formed of a disc-shaped metal plate 67 that is integrated with the case 65 by composite molding. This prevents problems such as shrinkage when the bottom surface 65c is formed of a resin, and has excellent flatness, thereby suppressing variations in discharge performance.

Prior art documents

Patent document

Patent document 1: japanese patent laid-open No. 2014-51964

Disclosure of Invention

Problems to be solved by the invention

As described above, in the internal gear pump of fig. 4 in which the housing is made of resin, a metal bush that is composite-molded (insert-molded) with the housing is used in order to maintain the connection strength at the connection portion of the pump. Here, in order to stably maintain the connection force, it is necessary to prevent the resin from being coated on the end surface on the cover side which is the joint surface between the bush and the cover at the time of the molding. Therefore, for example, it is conceivable that a bush forming surface around the bush of the housing is recessed from the sealing surface (the mating surface with the cover) and the bush end surface, and the bush is slightly protruded from the bush forming surface.

However, conventionally, the positional relationship after the molding of the seal surface, the bush forming surface, and the bush end surface has not been determined, and depending on the amount of protrusion of the bush and the molding conditions of the housing, the seal surface may be lower than the bush end surface. In this case, the bush is a bolted portion and therefore contacts the housing, but the seal surface does not contact the housing, and the sealability at this seal portion is not ensured. In this case, the sealing performance is ensured by the seal ring.

When the sealing property is secured by a seal ring of H-NBR system or the like, it cannot be used in an environment having a temperature higher than 120 ℃ which is the heat resistance temperature of the seal ring. In addition, in the pump manufacturing process, a seal ring mounting process is required.

The present invention (the following invention 1) is made to cope with such a problem, and an object thereof is to provide a ring gear pump capable of stably securing the sealing property between a resin case and a cover constituting a trochoid housing portion, omitting a seal ring at that portion, and stabilizing the discharge capacity.

In the internal gear pump described above with reference to fig. 4 and 8, the housing is manufactured by injection molding of resin in order to manufacture the pump at low cost, but the depth and diameter of the trochoid accommodation portion are kept unchanged in a state of completion of injection molding, and there is a slight variation from product to product. In particular, since the depth of the receiving portion affects the discharge amount, variation in depth may cause variation in discharge amount.

The present invention (the following 2 nd invention) is made to cope with such a problem, and an object thereof is to provide a ring gear pump capable of reducing variation in the depth of a trochoid accommodating portion between units and having a stable discharge capability.

Means for solving the problems

An internal gear pump according to claim 1 of the present application includes a trochoid portion in which an inner rotor having a plurality of outer teeth is rotatably accommodated in an outer rotor having a plurality of inner teeth in a state in which the outer teeth mesh with the inner teeth and are eccentric, an intake-side volume chamber into which a liquid is taken in and a discharge-side volume chamber from which the liquid taken into the intake-side volume chamber is discharged are formed between the inner teeth and the outer teeth, wherein the internal gear pump includes a case having a recess portion in which the trochoid portion is accommodated and a cover closing the recess portion of the case, the case is an injection-molded body of a resin composition, the case and the cover are fixed by bolts, a metal bush is provided in a bolt fixing hole portion of the case, and in a cross section of a joint portion between the case and the cover, a position of an end surface of the bush on the cover side is higher than a bush forming surface around the bush of the case as viewed from a bottom surface of the recess portion, and is the same as or lower than the sealing surface around the recess of the housing.

The sealing surface is a surface continuous from an inner surface of the recess of the case, and is in close contact with a surface of the cover to seal the recess.

The ring gear pump is not provided with a seal ring at a joint portion between the housing and the cover.

Wherein an inner side surface of the recess of the case is formed of an injection-molded body of the resin composition, and a bottom surface of the recess is formed of a metal body.

The resin composition is a resin composition in which a polyphenylene sulfide resin is used as a matrix resin and at least 1 selected from glass fibers, carbon fibers and inorganic fillers is blended in the matrix resin.

An internal gear pump according to claim 2 of the present application includes a trochoid line portion in which an inner rotor having a plurality of outer teeth is rotatably housed in an outer rotor having a plurality of inner teeth in a state in which the outer teeth mesh with the inner teeth and are eccentric, and a suction-side volume chamber for sucking liquid and a discharge-side volume chamber for discharging liquid sucked into the suction-side volume chamber are formed between the inner teeth and the outer teeth, wherein the trochoid line portion is housed in a sintered metal trochoid housing portion, and a case is joined to an outer side of the trochoid housing portion, the case is an injection-molded body of a resin composition, and the trochoid housing portion and the case are joined to each other through sintered micropores in which a part of the case enters an outer surface of the trochoid housing portion.

The trochoid housing portion includes a body portion having a cylindrical inner surface and a flat inner bottom surface, and a lid portion covering an opening portion of the body portion. The lid portion is fixed to the opening portion of the body portion by fastening (japanese character: add め).

In an embodiment in which the trochoid housing portion is formed of the main body portion and the lid portion, the trochoid housing portion and the housing are joined to each other through sintered pores in which a part of the housing enters the outer surfaces of the main body portion and the lid portion of the trochoid housing portion.

Effects of the invention

The internal gear pump of claim 1 of the present application includes a housing having a trochoid line housing recess and a cover closing the recess, the housing being an injection-molded body of a resin composition, the housing and the cover being fixed by a bolt, a metal bush being provided in a bolt-fixing hole portion of the housing, and an end face position of the bush being higher than a bush-forming surface around the bush of the housing and being the same as or lower than a sealing surface around the recess of the housing when viewed from a bottom surface of the trochoid line housing recess in a cross section of a joint portion between the housing and the cover. In addition, regardless of the molding conditions of the housing, the sealing surface is preferentially brought into close contact with the cover at the time of bolt fastening, and is in a form of always contacting, so that the sealing property of the trochoid accommodating recess can be stably ensured at this portion, and the discharge capability can be stabilized.

Further, since the sealing property is ensured as described above, a conventionally disposed seal ring can be omitted from the outer periphery of the sealing surface. Therefore, the pump manufacturing process does not require a seal ring mounting step, and assembly is facilitated. The O-ring can be used even in an environment having a temperature higher than 120 ℃ which is the heat resistance temperature of the H-NBR O-ring.

The sealing surface is a surface continuous from the inner side surface of the trochoid curve housing recess of the housing, and is in close contact with the surface of the cover to seal the recess, so that liquid can be prevented from entering between the cover and the housing from the trochoid curve housing recess.

Since the inner surface of the trochoid curve housing recess of the case is formed of an injection-molded body of a resin composition and the bottom surface of the recess is formed of a metal body, it is possible to improve frictional wear characteristics on the inner surface and suppress variations in discharge performance on the bottom surface.

The resin composition forming the case is a resin composition in which a polyphenylene sulfide resin is used as a matrix resin and at least 1 selected from glass fibers, carbon fibers, and inorganic fillers is blended with the matrix resin, and therefore, the resin composition is excellent in oil resistance and chemical resistance and greatly improved in dimensional accuracy.

The internal gear pump according to claim 2 of the present application includes a sintered metal trochoid housing portion that houses the trochoid portion, and a housing that is joined to the outside of the trochoid housing portion, wherein the housing is an injection-molded body of a resin composition, and the trochoid housing portion and the housing are joined through sintered pores that allow a part of the housing to enter the outer surface of the trochoid housing portion. That is, the trochoid housing portion and the housing are separate parts, and the housing is composite-molded (insert-molded) around the trochoid housing portion manufactured in advance, thereby having a structure in which two members are joined. By manufacturing the entire trochoid accommodating portion as a separate component, variations in accommodating portion depth between individuals can be reduced. In addition, the depth itself can be processed with high precision. As a result, a ring gear pump having stable discharge capability without variation in discharge amount among units is obtained.

In the case where the trochoid housing portion is formed in the housing as in the related art, the entire housing needs to be machined in order to suppress variation in the depth of the housing portion. The trochoid housing part with the adjusted depth can be formed by combining the housing with the trochoid housing part, and the additional processing cost can be reduced. Further, the trochoid housing portion is made of sintered metal, and therefore can be easily manufactured, and is firmly joined to the resin case by utilizing the anchoring effect of the sintered micropores at the time of composite molding.

Further, by making the trochoid housing portion an independent member, the discharge amount can be designed only by this portion. Therefore, the trochoid housing portion can be made into a common component. When the housing is formed, only the trochoid accommodating part is used for compound forming, so that the degree of freedom of design can be widened.

The trochoid housing portion includes a body portion having a cylindrical inner side surface and a flat inner bottom surface, and a lid portion covering an opening portion of the body portion, and therefore, adjustment of the housing portion depth can be performed only by planar processing of an axial cross section of the cylinder, and machining is easy.

Since the lid portion is fixed to the opening portion of the body portion by fastening, a conventional bolt fastening step is not required. Further, in the case of bolting the resin body and the metal body, there is a possibility that the connecting portion may loosen, but there is no fear that the main body portion and the lid portion are fixed by fastening.

In addition, the trochoid housing portion and the housing are joined through sintered pores in the outer surfaces of the main body portion and the lid portion, in which a part of the housing enters the trochoid housing portion, that is, the housing is formed so as to cover the lid portion side as well, and therefore, the lid portion can be prevented from coming off from the main body portion and the like.

Drawings

Fig. 1 is an assembled perspective view showing an example of an internal gear pump according to claim 1 of the present invention.

Fig. 2 is an axial sectional view and an enlarged view of the internal gear pump of fig. 1.

Fig. 3 is an axial sectional view and an enlarged view showing another example of the internal gear pump according to claim 1 of the present application.

Fig. 4 is an axial cross-sectional view of a conventional internal gear pump.

Fig. 5 is an axial cross-sectional view showing an example of the internal gear pump according to claim 2 of the present application.

Fig. 6 is an axial cross-sectional view showing another example of the internal gear pump according to claim 2 of the present application.

Fig. 7 is an axial cross-sectional view showing another example of the internal gear pump according to claim 2 of the present application.

Fig. 8 is an axial cross-sectional view of a conventional internal gear pump.

Detailed Description

An embodiment of a ring gear pump according to claim 1 of the present invention will be described with reference to fig. 1 and 2. Fig. 1 is an assembled perspective view of a ring gear pump, fig. 2(a) is an axial sectional view of the ring gear pump, and fig. 2(b) is an enlarged view of the periphery of a seal surface of a housing in the ring gear pump. As shown in fig. 1, the internal gear pump 1 includes: a trochoid portion (japanese: トロコイド)4 in which the inner rotor 3 is accommodated in the annular outer rotor 2; a case 5 in which a circular recess (trochoid accommodating recess) 5a for rotatably accommodating the trochoid portion 4 is formed; and a cover 6 for closing the trochoid accommodating recess 5a of the housing 5. The cover 6 has a shape substantially conforming to the outer shape of the upper surface of the housing 5 in which the trochoid accommodation recess 5a opens. As shown in fig. 2(a), the housing 5 and the cover 6 are connected to a fixing plate 11 fixed to the apparatus main body by bolts 9. Further, a drive shaft 10 is provided coaxially fixed to the rotation center of the inner rotor 3. The drive shaft 10 is supported by a bearing (not shown) or the like that is press-fitted into the cover 6.

The outer teeth of the inner rotor 3 are 1 less than the inner teeth of the outer rotor 2, and the inner rotor 3 is accommodated in the outer rotor 2 in an eccentric state in which the outer teeth are inscribed in and meshed with the inner teeth. Between the separation points where the rotors contact each other, the volume chambers on the intake side and the discharge side are formed in accordance with the rotational direction of the trochoid portion 4. A suction port communicating with the volume chamber on the suction side and a discharge port communicating with the volume chamber on the discharge side are formed in the bottom surface 5c of the trochoid curve housing recess 5a of the housing 5. Note that the suction port communicating with the suction-side volume chamber and the discharge port communicating with the discharge-side volume chamber may be formed in at least one of the housing 5, the cover 6, and the drive shaft 10.

In the internal gear pump 1, the margin portion 4 is rotated by the drive shaft 10, and the liquid is sucked from the suction port into the suction-side volume chamber whose volume increases and which becomes a negative pressure. The suction-side volume chamber becomes a discharge-side volume chamber whose volume decreases and whose internal pressure increases due to the rotation of the trochoid portion 4, and the liquid sucked in is discharged from the discharge-side volume chamber to the discharge port. The above-described pumping action is continuously performed by the rotation of the cycloid part 4, and the liquid is continuously pumped. Further, by utilizing the liquid sealing effect of improving the sealing property of each volume chamber by the liquid sucked, the pressure difference generated between the volume chambers becomes large, and a large pumping action can be obtained.

The cover 6 is made of metal, and the case 5 is an injection-molded body of a resin composition. When the resin case 5 is bolted to the apparatus main body, there is a fear that the connection portion is loosened due to creep deformation of the resin. As the resin material, although creep can be dealt with by using a predetermined resin composition containing a reinforcing agent or the like as described later, the resin material is sometimes brittle and poor in impact resistance. Therefore, in order to maintain the connection strength at the connection portion, a metal bush 7 is provided at the bolt fixing hole portion of the housing 5. The housing 5 and the cover 6 are connected to a fixing plate 11 fixed to the apparatus main body by bolts 9 inserted through the bushings 7.

The metal bush 7 has a cylindrical shape having a flange 7b, and is provided to penetrate the flange 5g of the housing 5. The bush 7 can be fixed to the housing 5 by press-fitting, or can be fixed by arranging the bush in a mold and integrating it by composite molding (insert molding) at the time of injection molding of the housing 5. In particular, by insert molding and using the bush 7 made of sintered metal, resin enters into the surface recess of the sintered body, and the bush 7 and the housing 5 are firmly joined by the anchor effect.

As shown in fig. 2(b), the sealing surface 5d is a surface continuous from the inner surface 5b of the trochoid accommodation recess 5a, and is in close contact with the surface of the cover to seal the mating surface of the housing 5 and the cover, thereby sealing the trochoid accommodation recess 5 a. In the case 5, the surface on the cover side contiguous to the inner surface 5b is a seal surface 5d, and thus, the liquid can be prevented from entering between the cover and the case from the trochoid curve housing recess.

In the internal gear pump according to claim 1 of the present application, the positional relationship between the seal surface of the housing and the end surface of the bushing after molding is characterized. That is, with reference to the bottom surface 5c of the trochoid accommodation recess 5a, the height position of the cover-side end surface 7a of the bush 7 is (1) higher than the bush forming surface 5e around the bush of the housing 5 and (2) lower than the seal surface 5d around the recess of the housing 5 as viewed from the bottom surface 5 c. This relationship is a positional relationship after the molding of the housing 5.

With the relationship (1), the end surface 7a of the bush 7 can be prevented from being coated with resin during composite molding of the housing 5 and the bush 7. The amount h1 of protrusion of the end surface 7a of the bush 7 from the bush forming surface 5e is, for example, 0.01mm to 0.3 mm. The resin coating can be prevented as long as the end surface 7a of the bush 7 slightly protrudes.

Because the seal surface 5d is located higher than the end surface 7a of the bush 7 due to the relationship (2), the seal surface 5d is preferentially brought into close contact with the cover at the time of bolt connection. Since the positional relationship after molding is defined, the sealing surface 5d is always in contact with the cover regardless of molding conditions, and the sealing performance of the trochoid accommodating recess portion 5a can be stably ensured and the discharge capability can be stabilized. Further, since sufficient sealing performance can be ensured by the seal surface 5d, a conventionally disposed seal ring can be omitted from the outer periphery of the seal surface 5d as shown in fig. 1 and 2.

The height of the end surface 7a of the bush 7 may be the same as the height of the seal surface 5d of the housing 5. In this case as well, the sealing performance at the sealing surface 5d can be ensured. Since the seal surface 5d can be brought into contact with the cover more stably, it is preferable that the seal surface 5d is located slightly higher than the end surface 7 a. The difference h2 between the height of the end surface 7a of the bush 7 and the height of the seal surface 5d of the housing 5 is, for example, 0.01mm to 0.3 mm.

In fig. 2(a), the housing 5 is in sliding contact with the outer rotor 2 and the inner rotor 3 on the bottom surface 5c and the inner side surface 5b constituting the trochoid accommodation recess 5 a. Since the inner surface 5b of the trochoid accommodation recess 5a is an injection-molded part of the resin composition, the frictional wear characteristics with the outer rotor 2 are excellent. The bottom surface 5c of the trochoid curve housing recess 5a is formed of a disk-shaped metal plate 8 integrated with the case 5 by composite molding. This provides superior flatness and can suppress variations in discharge performance as compared with the case where the bottom surface 5c is formed of a resin. As the metal plate 8, a sintered metal body or a molten metal body (sheet metal stamping part) can be used.

Further, by making the case 5 an injection-molded body of a resin composition, the liquid suction gate 5h can be formed integrally with the case 5 by the resin composition. The filter 13 can be fixed to an end of the liquid suction gate 5h serving as a communication passage inlet (liquid suction port) to the suction-side volume chamber by welding or the like, as necessary. The filter 13 prevents foreign matter from entering the pump. In the internal gear pump according to claim 1 of the present application, the configuration of the trochoid curve housing recess is not limited to the configuration shown in fig. 2, and an injection molded body of a resin composition may be used including the bottom surface. Thus, the trochoid housing recess can be formed by injection molding without a mechanical machining process, and is economical.

Fig. 3 shows another embodiment of the internal gear pump according to claim 1 of the present application. Fig. 3(a) is an axial sectional view of the ring gear pump, and fig. 3(b) is an enlarged view of the periphery of the sealing surface of the housing in the ring gear pump. As shown in fig. 3(a) and 3(b), the ring gear pump 1 has an annular groove 5f in a portion that seals the outer periphery of the trochoid accommodation recess 5a, and a seal ring 12 is attached to the groove 5 f. The other structure is the same as that of the internal gear pump shown in fig. 2. As shown in fig. 3(b), the sealing surface 5d is a surface continuous from the inner surface 5b of the trochoid curve housing recess 5a, and is in close contact with the surface of the cover to seal the trochoid curve housing recess 5a at the 1 st time. With reference to the bottom surface 5c of the trochoid-shaped housing recess 5a, the height position of the cover-side end surface 7a of the bush 7 is (1) higher than the bush-forming surface 5e around the bush of the housing 5 and (2) lower than the seal surface 5d around the recess of the housing 5, as viewed from the bottom surface 5 c.

In the ring gear pump of fig. 3, in addition to the seal structure, a seal ring 12 is attached, and the trochoid curve housing recess 5a is sealed by the seal ring 12 for the 2 nd time. Therefore, the sealing performance of the trochoid accommodating recess portion 5a can be ensured more stably, and the safety factor becomes higher. Note that, when the seal ring 12 is provided, the same applies to the amount of protrusion of the bush in the above-described seal structure. That is, in the embodiment of fig. 3, the amount h1 of protrusion of the end surface 7a of the bush 7 from the bush forming surface 5e and the difference h2 between the height of the end surface 7a of the bush 7 and the height of the seal surface 5d of the housing 5 are, for example, 0.01mm to 0.3mm, respectively.

The material of the seal ring is not particularly limited, and may be selected from rubber materials suitable for the intended use and use environment, such as hydrogenated nitrile rubber, fluororubber, and acrylic rubber. For example, in a scroll compressor of an air conditioner, heat resistance and oil resistance at about-30 to 120 ℃ are required, and therefore, hydrogenated nitrile rubber (H-NBR system) is preferably used.

The resin composition for forming the case is a resin composition in which a synthetic resin capable of injection molding is used as a matrix resin. Examples of the matrix resin include a plastic polyimide resin, a polyether ketone resin, a polyether ether ketone (PEEK) resin, a polyphenylene sulfide (PPS) resin, a polyamideimide resin, a Polyamide (PA) resin, a polybutylene terephthalate (PBT) resin, a polyethylene terephthalate (PET) resin, a Polyethylene (PE) resin, a polyacetal resin, and a phenol resin. These resins may be used alone or in combination of 2 or more. Among these heat-resistant resins, PPS resin is particularly preferably used because of its excellent creep resistance, load resistance, abrasion resistance, chemical resistance, and the like of the molded article.

Glass fibers, carbon fibers, or inorganic fillers are preferably used alone or in combination as appropriate, which are effective in imparting high strength, high elasticity, high dimensional accuracy, abrasion resistance, and anisotropy in removing injection molding shrinkage. In particular, the use of glass fibers and inorganic fillers in combination is economically excellent and has excellent frictional wear characteristics in oil.

In the invention 1 of the present application, it is particularly preferable to use a resin composition in which a linear PPS resin is used as a matrix resin and glass fibers and glass beads are blended as a filler in the matrix resin. With this structure, the flange portion is excellent in oil resistance and chemical resistance and excellent in toughness, and the warpage of the flange portion is reduced by removal of anisotropy of shrinkage by injection molding, and the dimensional accuracy is also greatly improved. In addition to this structure, the rubber seal ring is omitted as shown in fig. 2, and thus the present invention can be suitably used even in a high-temperature environment of more than 120 ℃.

The means for mixing and kneading these raw materials is not particularly limited, and the powdery raw materials may be dry-mixed by a henschel mixer (japanese: ヘンシェルミキサー), a ball mixer (japanese: ボールミキサー), a ribbon mixer, a rodgers mixer (japanese: レディゲミキサー), a super henschel mixer, or the like, and then melt-kneaded by a melt extruder such as a twin-screw extruder to obtain pellets for molding. In addition, the filler may be charged in a side direction in melt kneading by a twin-screw extruder or the like. The molding pellets are used to form a housing by injection molding. In the molding, a metal bush is disposed in a mold and integrated by composite molding. In addition, at the time of molding, the mold shape and molding conditions are set so that the bushing and the housing satisfy the above-described relationships (1) and (2) after molding.

In the internal gear pump according to claim 1 of the present application, as the cover, in addition to the above-described metal (iron, stainless steel, sintered metal, aluminum alloy, or the like), a resin (the same material as the case) may be used, or a composite molded product of a metal and a resin may be used. As the outer rotor and the inner rotor, sintered metals (iron-based, copper-based, stainless steel-based, etc.) are preferably used, and iron-based is particularly preferable from the viewpoint of cost. However, a trochoid pump that pumps water, a chemical solution, or the like may be made of stainless steel or the like having high rust prevention ability.

Fig. 5 shows an embodiment of a crescent gear pump according to claim 2 of the present application. Fig. 5 is an axial cross-sectional view of the internal gear pump. As shown in fig. 5, the ring gear pump 41 includes: a trochoid portion 44 in which an inner rotor 43 is accommodated in the annular outer rotor 42; a trochoid housing portion 46 that houses the trochoid portion 44 so as to be rotatable; and a housing 45 that is engaged with and supports the outside of the trochoid housing portion 46. The trochoid housing portion 46 includes: a body portion 47 having a cylindrical inner side surface 47b and a flat inner bottom surface 47c, and a lid portion 48 covering the opening 47a of the body portion 47. Further, a drive shaft 49 is provided coaxially fixed to the rotation center of the inner rotor 43. The drive shaft 49 is supported by a bearing (not shown) provided in the housing 45 or the like. The cover 48 and the housing 45 have an opening at a portion through which the drive shaft 49 passes. The ring gear pump 41 is connected and fixed to a member (not shown) of the apparatus main body by bolts through bolt fixing holes 50 formed in the flange 45b of the housing 45.

The outer teeth of the inner rotor 43 are less than the inner teeth of the outer rotor 42 by 1, and the inner rotor 43 is accommodated in the outer rotor 42 in an eccentric state in which the outer teeth are inscribed and meshed with the inner teeth. Between the separation points where the rotors contact each other, the suction-side and discharge-side volume chambers are formed in accordance with the rotational direction of the cycloid portion 44. An intake port communicating with the intake-side volume chamber and an exhaust port communicating with the exhaust-side volume chamber are formed in an inner bottom surface 47c of the main body portion 47 of the trochoid housing portion 46 of the housing 45.

In the ring gear pump 41, the surplus swing portion 44 is rotated by the drive shaft 49, and the liquid is sucked from the suction port into the suction-side volume chamber whose volume increases and which becomes a negative pressure. The suction-side volume chamber becomes a discharge-side volume chamber whose volume decreases and whose internal pressure increases due to the rotation of the trochoid portion 44, and the liquid sucked in is discharged from the discharge-side volume chamber to the discharge port. The above-described pumping action is continuously performed by the rotation of the margin portion 44, and the liquid is continuously pumped. Further, by utilizing the liquid sealing effect of improving the sealing property of each volume chamber by the liquid sucked, the pressure difference generated between the volume chambers becomes large, and a large pumping action can be obtained.

The trochoid housing portion 46 (the main body portion 47 and the lid portion 48) is made of sintered metal, and the case 45 is an injection-molded body of a resin composition. The trochoid housing portion 46 and the housing 45 are integrated (insert molded) by composite molding by disposing the trochoid housing portion 46 in a mold at the time of injection molding of the housing 45. In terms of structure, a part of the resin constituting the case 45 enters a part of the sintered micropores on the outer surface of the trochoid accommodation portion as a sintered body, and is firmly joined by an anchor effect.

In the embodiment shown in fig. 5, the housing 45 is formed to cover not only the main body portion 47 of the trochoid housing portion 46 but also the lid portion 48. In order to adopt this method, in manufacturing, first, the inner rotor 43 and the outer rotor 42 are combined from the opening 47a side and inserted into the body portion 47 of the trochoid housing portion 46, and then the lid portion 48 is covered to obtain the trochoid housing portion 46 including the rotor. The case 45 can be formed by placing the molded product in an injection mold and performing the above-described composite molding so as to cover the lid 48. With this structure, the lid portion 48 can be prevented from coming off the body portion 47.

Examples of the sintered metal material that can be used for forming the trochoid accommodating portion 46 include iron-based, copper-based, and stainless steel-based materials. Since it is inexpensive and has excellent adhesion to a resin case, it is preferable to use a sintered metal containing iron as a main component (copper may be contained). Further, by using a sintered metal containing iron as a main component, higher mechanical strength can be obtained. In the case of containing copper, the content of copper is preferably 10 wt% or less because copper is inferior in adhesion (adhesiveness) to a resin compared with iron. More preferably, the copper content is 5 wt% or less. In addition, stainless steel or the like having high rust-proof ability is preferably used for the trochoid pump that pumps water, chemical solution, or the like.

As the sintered metal constituting the trochoid housing portion 46, a sintered metal not impregnated with oil is preferably used. When oil is used in the step of forming or re-press forming (coining) of the sintered metal, it is preferable to use a non-oil-containing sintered metal from which oil has been removed by solvent cleaning or the like. The theoretical density ratio of the sintered metal is preferably 0.7 to 0.9. By setting the theoretical density ratio to 0.7 to 0.9, it is possible to secure surface irregularities (sintered pores) for firmly adhering the resin case to the trochoid curve housing portion while securing the required compactness for securing the strength of the trochoid curve housing portion.

The adjustment of the receiving portion depth of the trochoid receiving portion 46 can be performed by performing planar processing on the axial cross section of the cylindrical side wall of the main body portion 47, and can be easily adjusted by machining.

Since the housing 45 is an injection molded body of a resin composition and the discharge amount can be designed by adjusting only the trochoid accommodation portion 46, the degree of freedom in design is increased with respect to the pump shape and the like. In addition, the liquid suction gate 45a can be formed integrally with the housing 45 by the resin composition. If necessary, a filter for preventing the mixing of foreign matter may be fixed to an end of the liquid suction gate 45a serving as a communication passage inlet (liquid suction port) to the suction-side volume chamber by welding or the like.

The resin composition forming the case 45 is a resin composition having a synthetic resin as a matrix resin, which can be injection molded. Examples of the matrix resin include a plastic polyimide resin, a polyether ketone resin, a polyether ether ketone (PEEK) resin, a polyphenylene sulfide (PPS) resin, a polyamideimide resin, a Polyamide (PA) resin, a polybutylene terephthalate (PBT) resin, a polyethylene terephthalate (PET) resin, a Polyethylene (PE) resin, a polyacetal resin, and a phenol resin. These resins may be used alone or as a polymer alloy of 2 or more kinds. Among these heat-resistant resins, PPS resin is particularly preferably used because the molded article is excellent in creep resistance, load resistance, abrasion resistance, chemical resistance, and the like.

In the invention 2 of the present application, it is particularly preferable to use a resin composition in which a linear PPS resin is used as a matrix resin and glass fibers and glass beads are mixed as a filler in the matrix resin. With this structure, the flange portion is excellent in oil resistance and chemical resistance and excellent in toughness, and the warpage of the flange portion is reduced by removal of anisotropy of shrinkage by injection molding, and the dimensional accuracy is also greatly improved. In addition to this structure, the trochoid housing portion has a separate trochoid housing portion, and a conventional rubber seal ring is not required, and therefore, the trochoid housing portion can be suitably used even in a high-temperature environment of more than 120 ℃.

The means for mixing and kneading these raw materials is not particularly limited, and the powdery raw materials may be dry-mixed by a henschel mixer, a ball mixer, a ribbon mixer, a rodgers mixer, a super henschel mixer, or the like, and then melt-kneaded by a melt extruder such as a twin-screw extruder to obtain pellets for molding. In addition, the filler may be charged in a side direction in melt kneading by a twin-screw extruder or the like. The molding pellets are used to form a housing by injection molding. In molding, the trochoid accommodating portion is entirely or only the main body portion is disposed in the mold, and the trochoid accommodating portion and the main body portion are integrated by composite molding.

In the internal gear pump according to claim 2 of the present application, sintered metal (iron-based, cupronickel-based, copper-based, stainless steel-based, etc.) is preferably used as the outer rotor and the inner rotor in the same manner as the trochoid housing portion.

Fig. 6 shows another embodiment of the internal gear pump according to claim 2 of the present application. Fig. 6 is an axial cross-sectional view of the internal gear pump. As shown in fig. 6, the internal gear pump 41 has a structure in which a lid 48 is exposed from a case 45. The other structure is the same as that of the internal gear pump shown in fig. 5. In the embodiment shown in fig. 6, the trochoid housing 46 can be manufactured by a step of composite molding the main body portion 47 and the housing 45 of the trochoid housing, and then inserting the rotors into the main body portion 47 and the cover portion 48. In addition, as in the case of fig. 5, the trochoid housing portion 46 including the rotor may be assembled and then may be formed by composite molding with the housing. The body portion 47 and the lid portion 48 are fastened and fixed to each other, so that a bolt fastening process or the like is not required, and the body portion and the lid portion can be fixed to each other with ease and firmness.

Fig. 7 shows another embodiment of the internal gear pump according to claim 2 of the present application. Fig. 7 is an axial sectional view of the internal gear pump. As shown in fig. 7, the ring gear pump 41 has a structure in which a lid 48 and a case 45 are connected by a bolt 51. Thereby, the body portion 47 and the lid portion 48 are in close contact with each other in the trochoid accommodation portion 46. The other structure is the same as that of the internal gear pump shown in fig. 5. Further, if necessary, a metal bush may be inserted into the bolt fixing hole 50 in the flange portion 45b of the housing 45, and the bolt connection may be performed through the bush. In the embodiment shown in fig. 7, after the main body portion 47 of the trochoid housing portion 46 and the housing 45 are composite molded, each rotor is inserted into the main body portion 47. Thereafter, the cover 48 can be manufactured by a step of bolting it to the case 45.

The ring gear pump according to the invention 2 of the present application is not limited to the above-described configuration, although the description has been made with reference to fig. 5 to 7. In either of these embodiments, the trochoid housing portion and the housing are separate parts, and the housing is formed by composite molding around the trochoid housing portion manufactured by machining the housing portion in advance with high accuracy, so that both members are joined. Thus, a ring gear pump having stable discharge capacity without variation in discharge amount among units is obtained.

Industrial applicability

The internal gear pump according to the first or second aspect of the present invention is applicable as an internal gear pump (trochoid pump) for pumping a liquid such as oil, water, or a chemical liquid, and is particularly suitable as a pump for supplying a liquid to a sliding portion of a scroll compressor for use in electric water heaters, room air conditioners, and vehicle air conditioners, which use a substitute for freon, carbon dioxide, or the like as a refrigerant.

Description of the reference numerals

1 internal gear pump

2 outer rotor

3 inner rotor

4 trochoid parts

5 casing

6 cover

7 liner

8 Metal plate

9 bolt

10 drive shaft

11 fixed plate of equipment body

12 sealing ring

13 Filter

41 internal gear pump

42 outer rotor

43 inner rotor

44 trochoid portion

45 casing

46 more than cycloid containing parts

47 Main body part

48 cover part

49 drive shaft

50 bolt fixing hole

51 bolts.

Claims

1. A ring gear pump having a trochoid portion in which an inner rotor having a plurality of outer teeth is rotatably housed in an outer rotor having a plurality of inner teeth in a state in which the outer teeth mesh with the inner teeth and are eccentric, and a suction-side volume chamber for sucking a liquid and a discharge-side volume chamber for discharging the liquid sucked into the suction-side volume chamber are formed between the inner teeth and the outer teeth,

the internal gear pump has a sintered metal trochoid housing portion that houses the trochoid portion, and a housing that is joined to the outside of the trochoid housing portion,

the housing is an injection-molded body of a resin composition, and the trochoid housing portion and the housing are joined through sintered micropores, through which a portion of the housing enters the outer surface of the trochoid housing portion.

2. A crescent gear pump according to claim 1,

the trochoid housing portion includes a main body portion having a cylindrical inner side surface and a flat inner bottom surface, and a lid portion covering an opening portion of the main body portion.

3. A crescent gear pump according to claim 2,

the lid portion is fixed to the opening portion of the body portion by fastening.

4. A crescent gear pump according to claim 2,

the trochoid housing portion and the housing are joined to each other through sintered pores in the outer surfaces of the body portion and the lid portion, into which a part of the housing enters the trochoid housing portion.