WO2017057533A1

WO2017057533A1 - Inscribed gear pump

Info

Publication number: WO2017057533A1
Application number: PCT/JP2016/078755
Authority: WO
Inventors: 一淺田; 圭服部; 伊藤　貴之; 洋赤井
Original assignee: Ntn株式会社
Priority date: 2015-09-30
Filing date: 2016-09-29
Publication date: 2017-04-06
Also published as: CN110360096A; US20180274539A1; CN108138766A; CN108138766B; DE112016004484T5

Abstract

Provided is an inscribed gear pump with which sealing can be stably ensured between a cover and a plastic casing constituting a trochoid housing part, a seal ring can be omitted in this portion, and discharge capability can be stabilized. An inscribed gear pump 1 has a trochoid 4 in which an inner rotor 3 having a plurality of external teeth is eccentrically accommodated within an outer rotor 2 having a plurality of internal teeth such that the external teeth mesh with the internal teeth, a casing 5 in which a trochoid-accommodating recess 5a is formed, and a cover 6 that closes off the recess 5a. The casing 5 is an extrusion-molded compact of a resin composition, the casing 5 and cover 6 are secured by a bolt, a bolt-securing hole portion of the casing 5 has a metal bushing 7, and in a cross-section of the juncture between the casing 5 and the cover 6, the position of an end surface 7a of the bushing 7 is higher than a bushing-forming surface 5e in a bushing periphery of the casing 5 and lower than a seal surface 5d in a recess periphery of the casing 5, as viewed from a bottom surface 5a of the recess 5a.

Description

Internal gear pump

The present invention relates to an internal gear pump (trochoid pump) that pumps liquids such as oil, water, and chemicals.

An internal gear pump (trochoid pump) is configured such that an outer rotor and an inner rotor having a trochoidal tooth shape are sealed in a casing, and an inner rotor and an outer rotor fixed to the drive shaft rotate along with the rotation of the drive shaft. It is a pump which acts to inhale and discharge. In recent years, a pump having a resin casing has been known as a pump of this type that can reduce the machining process and can be manufactured at low cost (see Patent Document 1).

Referring to FIGS. 4 and 8, the structure of this type of internal gear pump will be described.

FIG. 4 is a sectional view of a conventional internal gear pump. As shown in FIG. 4, the pump 21 is mainly composed of a trochoid 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 24 is rotatably accommodated in a circular trochoid accommodating recess 25a formed in a cylindrical casing 25 with a flange. A cover 26 that closes the trochoid-containing recess 25 a is fixed to the casing 25.

The trochoid 24 is configured such that the inner rotor 23 is rotatably accommodated in the outer rotor 22 with the outer teeth of the inner rotor 23 meshing with the inner teeth of the outer rotor 22 and is eccentric. Between the partition points where the rotors contact each other, the suction-side and discharge-side volume chambers are formed according to the rotational direction of the trochoid 24. A drive shaft 29 that is rotated by a drive source (not shown) is fixed through the shaft center of the inner rotor 23. 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 so that the outer rotor 22 rotates in the same direction. Liquid is sucked into the chamber from the inlet. The suction-side volume chamber is changed to a discharge-side volume chamber in which the volume is reduced and the internal pressure is increased by the rotation of the trochoid 24, from which the sucked liquid is discharged to the discharge port.

The cover 26 is made of sintered metal, and the casing 25 is an injection-molded body manufactured by injection molding using a resin composition. A metal bush 27 is integrated into the bolt fixing hole portion of the casing 25 by composite molding at the time of injection molding, and the casing 25 and the cover 26 are connected to the main body of the device by the bolt 28 passed through the bush 27. The fixing plate 30 is fastened and fixed. The reason why the bush 27 is interposed in the fastening of the casing 25 and the cover 26 is to maintain the fastening strength at the fastening portion.

A seal ring (O-ring) 31 is assembled in a groove 32 formed on the outer periphery of the concave portion of the casing 25 on the joining surface (mating surface) of the casing 25 and the cover 26. Thereby, the trochoid accommodation recessed part 25a is sealed and the leakage of the liquid from the mating surface of the casing 25 and the cover 26 can be prevented. In the internal gear pump, in order to effectively exhibit the pump function, it is important to stably secure the sealing performance (sealing performance of the trochoid-receiving recess 25a) at the mating surface of the casing 25 and the cover 26. As the material of the seal ring 31, hydrogen nitrile rubber (H-NBR system) is used because it has heat resistance and oil resistance of about −30 to 120 ° C. and can be applied to a scroll compressor of an air conditioner. .

FIG. 8 is a sectional view of another conventional internal gear pump. As shown in FIG. 8, the pump 61 mainly includes a trochoid 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 64 is rotatably accommodated in a circular trochoid accommodating recess 65a formed in a cylindrical casing 65 with a flange. A cover 66 that closes the trochoid-containing recess 65a is fixed to the casing 65.

The trochoid 64 is configured such that the inner rotor 63 is rotatably accommodated in the outer rotor 62 with the outer teeth of the inner rotor 63 meshing with the inner teeth of the outer rotor 62 and is eccentric. Between the partition points where the rotors are in contact with each other, the suction-side and discharge-side volume chambers are formed according to the rotational direction of the trochoid 64. A drive shaft 69 that is rotated by a drive source (not shown) is fixed through the shaft center of the inner rotor 63. When the drive shaft 69 rotates and the inner rotor 63 rotates, the outer teeth mesh with the inner teeth of the outer rotor 62, whereby the outer rotor 62 is rotated in the same direction, the volume increases by this rotation, and the suction side volume becomes negative pressure. Liquid is sucked into the chamber from the inlet. The suction-side volume chamber is changed to a discharge-side volume chamber in which the volume is reduced and the internal pressure is increased by the rotation of the trochoid 64, and the sucked liquid is discharged from the discharge port to the discharge port.

The cover 66 is made of sintered metal, and the casing 65 is an injection-molded body manufactured by injection molding using a resin composition. The casing 65 and the cover 66 are fastened and fixed to the fixing plate 70 of the apparatus main body by bolts 68. Further, a seal ring 71 is assembled in a groove formed on the outer periphery of the concave portion of the casing 65 on the joint surface (matching surface) between the casing 65 and the cover 66. Thereby, the trochoid accommodation recessed part 65a is sealed and the leakage of the liquid from the mating surface of the casing 65 and the cover 66 used as the combination of resin and a sintered metal is prevented.

By using the casing 65 as an injection molded body (resin molded body), machining is unnecessary and economical. In addition, the casing 65 is in sliding contact with the outer rotor 62 and the inner rotor 63 at the bottom surface 65c and the inner side surface 65b constituting the trochoid accommodating recess 65a. Since the inner side surface 65b of the trochoid-containing recess 65a is an injection-molded body portion of the resin composition, the frictional wear characteristic with the outer rotor 62 is excellent. Further, the bottom surface 65c of the trochoid accommodating recess 65a is constituted by a disk-shaped metal plate 67 integrated with the casing 65 by composite molding. Thereby, problems such as sink marks when the bottom surface 65c is formed of resin do not occur, the flatness is excellent, and variations in ejection performance are suppressed.

JP 2014-51964 A

As described above, in the internal gear pump in which the casing of FIG. 4 is made of resin, in order to maintain the fastening strength at the fastening portion of the pump, a metal bush combined with the casing (insert molding) is used. Yes. Here, in order to stably hold the fastening force, it is necessary to prevent the cover side end surface, which is a joint surface with the cover of the bush, from being covered with the resin during the molding. For this purpose, for example, it is conceivable that the bush forming surface around the bush of the casing is recessed from the seal surface (the mating surface with the cover) or the bush end surface, and the bush is slightly protruded from the bush forming surface.

However, the positional relationship after molding of the seal surface, the bush forming surface, and the bush end surface has not been determined so far, and the seal surface may be lower than the bush end surface depending on the protruding amount of the bush and the molding conditions of the casing. In that case, since the bush is a bolt fastening portion, it comes into contact with the cover, but the sealing surface is not in contact with the cover, and the sealing performance at the sealing portion is not ensured. In this case, the sealing performance is ensured by the seal ring.

When sealing performance is secured by a seal ring such as H-NBR, it cannot be used in an atmosphere higher than the heat resistant temperature of 120 ° C. Further, in the pump manufacturing process, an assembly process of the seal ring is required.

The present invention (the following first invention) is made to cope with such a problem, and can stably secure the sealing performance between the resin casing and the cover constituting the trochoid housing part, An object of the present invention is to provide an internal gear pump that can omit the seal ring at the portion and can stabilize the discharge capacity.

Further, in the internal gear pump as described above with reference to FIGS. 4 and 8, the casing is manufactured by injection molding of resin in order to manufacture the pump at a low cost. The diameter dimension remains the same as the injection-molded finish, and there are slight variations from product to product. In particular, since the depth of the storage portion affects the discharge amount, variations in depth can cause variations in the discharge amount.

The present invention (the second invention described below) has been made in order to cope with such a problem, and can reduce the variation in the depth of the trochoid housing portion among individuals, and has an internal gear having a stable discharge capability. The object is to provide a pump.

In the internal gear pump of the first invention of the present application, an inner rotor having a plurality of external teeth is rotatable in an outer rotor having a plurality of internal teeth in a state where the external teeth mesh with the internal teeth and are eccentric. An internal trochoid that is accommodated and has a suction side volume chamber for sucking liquid and a discharge side volume chamber for discharging the liquid sucked into the suction side volume chamber between the inner teeth and the outer teeth. A contact gear pump, comprising a casing having a recess for housing the trochoid, and a cover for closing the recess of the casing, wherein the casing is an injection-molded body of a resin composition, and the casing and the cover And has a metal bush in the bolt fixing hole portion of the casing, and in the section of the joint between the casing and the cover, The end face position on the-side is higher than the bush forming surface around the bush of the casing and lower than the seal surface around the recess of the casing or lower than the seal surface when viewed from the bottom surface of the recess. To do.

The sealing surface is a surface continuous from the inner surface of the concave portion of the casing, and is in close contact with the surface of the cover to seal the concave portion.

The internal gear pump is characterized in that no seal ring is interposed at the joint portion of the casing with the cover.

The inner surface of the recess of the casing is made of an injection-molded body of the resin composition, and the bottom surface of the recess is made of a metal body.

The resin composition is a resin composition comprising a polyphenylene sulfide resin as a base resin and blended with at least one selected from glass fiber, carbon fiber, and inorganic filler.

The internal gear pump of the second invention of the present application is such that an inner rotor having a plurality of external teeth is rotatable in an outer rotor having a plurality of internal teeth in a state where the external teeth mesh with the internal teeth and are eccentric. An internal trochoid that is accommodated and has a suction side volume chamber for sucking liquid and a discharge side volume chamber for discharging the liquid sucked into the suction side volume chamber between the inner teeth and the outer teeth. A contact gear pump, comprising: a sintered metal trochoid housing for housing the trochoid; and a casing joined to the outside of the trochoid housing, wherein the casing is an injection-molded body of a resin composition. The trochoid accommodating part and the casing are characterized in that a part of the casing enters and joins the sintered pores on the outer surface of the trochoid accommodating part.

The trochoid housing portion is characterized by comprising a main body portion having a cylindrical inner side surface and a flat inner bottom surface, and a lid portion for closing the opening of the main body portion. The lid portion may be fixed by crimping to the opening of the main body portion.

Further, in the form in which the trochoid housing portion is composed of the main body portion and the lid portion, the trochoid housing portion and the casing are configured such that a part of the casing is outside the main body portion and the lid portion in the trochoid housing portion. It is characterized by entering and joining the sintered pores on the surface.

An internal gear pump according to a first invention of the present application includes a casing having a trochoid-containing recess and a cover that closes the recess, the casing is an injection-molded body of a resin composition, and the casing and the cover are bolted. A bushing made of metal in the bolt fixing hole portion of the casing, and in the cross section of the joint portion between the casing and the cover, the position of the end surface of the bushing is the bushing around the bushing of the casing when viewed from the bottom surface of the trochoid receiving recess. Since it is higher than the formation surface and is the same as or lower than the seal surface around the concave portion of the casing, it is possible to prevent the bush end surface from being covered with resin when the casing is molded. In addition, regardless of the molding conditions of the casing, the sealing surface preferentially adheres to the cover when bolts are tightened, and always comes into contact with it, so that the sealing performance of the trochoid-receiving recess can be stably secured, and the discharge capacity is also stabilized. Is done.

Also, as described above, since the sealing performance is guaranteed, the seal ring that has been conventionally arranged on the outer periphery of the seal surface can be omitted. For this reason, the assembly process of a seal ring is unnecessary in a pump manufacturing process, and assembly becomes easy. Further, it can be used even in an atmosphere higher than 120 ° C. which is the heat resistant temperature of the H—NBR O-ring.

The sealing surface is a surface continuous from the inner surface of the trochoid-accommodating recess of the casing and seals the recess in close contact with the surface of the cover, so that liquid enters between the cover and the casing from the trochoid-accommodating recess. Can be prevented.

Since the inner side surface of the trochoid-containing recess of the casing is made of an injection-molded body of the resin composition, and the bottom surface of the recess is made of a metal body, discharge performance is improved at the bottom surface while improving the friction and wear characteristics on the inner side surface. The variation of can be suppressed.

Since the resin composition forming the casing is a resin composition comprising a polyphenylene sulfide resin as a base resin and blended with at least one selected from glass fiber, carbon fiber, and inorganic filler, oil resistance, Excellent chemical resistance and greatly improves dimensional accuracy.

An internal gear pump according to a second invention of the present application has a sintered metal trochoid housing portion that houses a trochoid, and a casing joined to the outside of the trochoid housing portion, and the casing is an injection molded body of a resin composition. The trochoid housing part and the casing are joined by joining a part of the casing into the sintered pores on the outer surface of the trochoid housing part. That is, the trochoid housing part is a separate component from the casing, and the casing is combined and molded (insert molding) around the trochoid housing part produced in advance, thereby having a structure in which both members are joined. By manufacturing the entire trochoid accommodating part as a separate part, variation in the accommodating part depth among individuals can be reduced. Moreover, the depth itself can be processed with high accuracy. As a result, the internal gear pump has no variation in discharge amount among individuals and has a stable discharge capacity.

When the trochoid housing part is formed in the casing as in the prior art, the entire casing needs to be processed in order to suppress variations in the depth of the housing part, but only the trochoid housing part should be a separate part. This eliminates that need. The depth-adjusted trochoid housing part may be combined with the casing to reduce the additional work cost. Furthermore, since the trochoid accommodating part is made of sintered metal, it can be easily manufactured, and is firmly joined to the resin casing by the anchor effect to the sintered pores during composite molding.

Also, by making the trochoid housing part an independent part, the discharge amount can be designed only by this part. For this reason, a trochoid accommodating part can be made into a common component. At the time of molding the casing, the trochoid housing part is only used for composite molding, and the degree of design freedom can be expanded.

Since the trochoid accommodating part is composed of a main body part having a cylindrical inner side surface and a flat inner bottom surface, and a lid part for closing the opening part of the main body part, the adjustment of the accommodating part depth is performed on the axial cross section of the cylinder. It can be executed only by plane machining and is easy to machine.

Since the lid is crimped and fixed to the opening of the main body, the conventional bolting process is not required. Further, in the case where the resin body and the metal body are bolted together, the fastening portion may be loosened, but there is no such concern by fixing the main body portion and the lid portion by caulking.

Further, the trochoid housing part and the casing are joined so that a part of the casing enters the sintered pores on the outer surface of the main body part and the lid part in the trochoid housing part, that is, covers the lid part side. Since the casing is formed on the main body, it is possible to prevent the lid from coming off from the main body.

It is an assembly perspective view which shows an example of the internal gear pump of 1st invention of this application. It is an axial sectional view and an enlarged view of the internal gear pump of FIG. It is an axial sectional view and an enlarged view showing another example of the internal gear pump of the first invention of the present application. It is an axial sectional view of a conventional internal gear pump. It is an axial sectional view showing an example of the internal gear pump of the second invention of the present application. It is axial direction sectional drawing which shows the other example of the internal gear pump of 2nd invention of this application. It is axial direction sectional drawing which shows the other example of the internal gear pump of 2nd invention of this application. It is an axial sectional view of a conventional internal gear pump.

One embodiment of the internal gear pump of the first invention of the present application will be described with reference to FIGS. FIG. 1 is an assembled perspective view of the internal gear pump, FIG. 2 (a) is an axial sectional view of the internal gear pump, and FIG. 2 (b) is the vicinity of the sealing surface of the casing in the internal gear pump. FIG. As shown in FIG. 1, the internal gear pump 1 includes a trochoid 4 in which an inner rotor 3 is accommodated in an annular outer rotor 2, and a circular recess (trochoid accommodating recess) 5a in which the trochoid 4 is rotatably accommodated. The formed casing 5 and the cover 6 that closes the trochoid-containing recess 5 a of the casing 5 are provided. The cover 6 has a shape that substantially matches the outer shape of the upper surface of the casing 5 in which the trochoid-containing recess 5a is opened. As shown in FIG. 2A, the casing 5 and the cover 6 are fastened and fixed to the fixing plate 11 of the device main body by bolts 9. The drive shaft 10 is coaxially fixed to the rotation center of the inner rotor 3. The drive shaft 10 is supported by a bearing (not shown) press-fitted into the cover 6.

The outer teeth of the inner rotor 3 are one less than the inner teeth of the outer rotor 2, and the inner rotor 3 is housed in the outer rotor 2 in an eccentric state in which the outer teeth are inscribed in mesh with the inner teeth. Between the partition points where the rotors are in contact with each other, the suction-side and discharge-side volume chambers are formed according to the rotational direction of the trochoid 4. The bottom surface 5c of the trochoid accommodating recess 5a of the casing 5 is formed with a suction port that communicates with the suction-side volume chamber and a discharge port that communicates with the discharge-side volume chamber. 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 casing 5, the cover 6, and the drive shaft 10.

In the internal gear pump 1, the trochoid 4 is rotated by the drive shaft 10, whereby the liquid is sucked from the suction port into the suction-side volume chamber where the volume increases and becomes negative pressure. The suction-side volume chamber changes to a discharge-side volume chamber in which the volume decreases and the internal pressure increases as the trochoid 4 rotates, and the sucked liquid is discharged from the discharge-side volume chamber to the discharge port. The above pumping action is continuously performed by the rotation of the trochoid 4, and the liquid is continuously pumped. Furthermore, due to the liquid sealing effect in which the sealing performance of each volume chamber is enhanced by the sucked liquid, the differential pressure generated between the volume chambers is increased, and a large pumping action is obtained.

The cover 6 is made of metal, and the casing 5 is an injection-molded body of a resin composition. When the resin casing 5 is bolted to the apparatus main body, there is a concern that the fastening portion is loosened due to creep deformation of the resin. Although a countermeasure against creep is possible by using a predetermined resin composition containing a reinforcing agent as described later as a resin material, it may be brittle and inferior in impact resistance. For this reason, in order to maintain the fastening strength at the fastening portion, a metal bush 7 is provided in the bolt fixing hole portion of the casing 5. The casing 5 and the cover 6 are fastened and fixed to a fixing plate 11 of the apparatus main body by a bolt 9 passed through the bush 7.

The metal bush 7 has a cylindrical shape having a flange 7 b and is provided through the flange portion 5 g of the casing 5. The bush 7 can be fixed to the casing 5 by press-fitting, or can be fixed by being integrated (insert molding) by composite molding by placing the bush in a mold when the casing 5 is injection molded. In particular, by adopting insert molding and using a bush 7 made of sintered metal, the resin enters the surface concave portion of the sintered body, and the bush 7 and the casing 5 are firmly joined by the anchor effect.

As shown in FIG. 2 (b), the seal surface 5d is a surface continuous from the inner surface 5b of the trochoid-containing recess 5a and seals the mating surface of the casing 5 and the cover in close contact with the surface of the cover. The housing recess 5a is sealed. In the casing 5, the cover-side surface that is adjacent to the inner side surface 5 b is formed as the sealing surface 5 d, so that liquid can be prevented from entering between the cover and the casing from the trochoid-containing recess.

The internal gear pump of the first invention of the present application is characterized by the positional relationship after molding between the seal surface of the casing and the end surface of the bush. That is, the height position of the end surface 7a on the cover side of the bush 7 is higher than the bush forming surface 5e around the bush of the casing 5 as viewed from the bottom surface 5c with respect to the bottom surface 5c of the trochoid receiving recess 5a, and (2) The position is lower than the seal surface 5d around the recess of the casing 5. This relationship is a positional relationship after the casing 5 is molded.

Due to the relationship (1), it is possible to prevent the end surface 7a of the bush 7 from being covered with the resin when the casing 5 and the bush 7 are combined. Projection amount _{h 1} from the bushing forming surface 5e of the end face 7a of the bush 7 is, for example, 0.01 mm ~ 0.3 mm. If the end surface 7a of the bush 7 protrudes even slightly, the above-described resin coating can be prevented.

Because of the relationship (2), the seal surface 5d is positioned higher than the end surface 7a of the bush 7, so that the seal surface 5d is in close contact with the cover preferentially when the bolt is fastened. Since it is defined as a positional relationship after molding, the seal surface 5d is always in contact with the cover regardless of molding conditions, the sealing performance of the trochoid-receiving recess 5a can be stably secured, and the discharge capacity is also stabilized. . Moreover, since sufficient sealing performance can be ensured by the seal surface 5d, the seal ring conventionally disposed on the outer periphery of the seal surface 5d can be omitted as shown in FIGS.

Further, the height of the end surface 7a of the bush 7 and the height of the seal surface 5d of the casing 5 may be the same. In this case as well, the sealing performance at the seal surface 5d can be secured. Since the seal surface 5d and the cover can be more stably brought into contact with each other, the seal surface 5d is preferably positioned slightly higher than the end surface 7a. The difference _{h 2} between the height of the sealing surface 5d of the height and the casing 5 of the end face 7a of the bush 7 is, for example, 0.01 mm ~ 0.3 mm.

2 (a), the casing 5 is in sliding contact with the outer rotor 2 and the inner rotor 3 at the bottom surface 5c and the inner side surface 5b constituting the trochoid accommodating recess 5a. Since the inner side surface 5b of the trochoid-containing recess 5a is an injection-molded body portion of the resin composition, the frictional wear characteristic with the outer rotor 2 is excellent. Further, the bottom surface 5c of the trochoid-containing recess 5a is composed of a disk-shaped metal plate 8 integrated with the casing 5 by composite molding. Thereby, it is excellent in flatness compared with the case where the bottom face 5c is formed with resin, and the dispersion | variation in discharge performance can be suppressed. As the metal plate 8, a sintered metal body or a molten metal body (sheet metal press product) can be adopted.

Further, by using the casing 5 as an injection molded body of the resin composition, the liquid suction nozzle 5h can be formed integrally with the casing 5 from the resin composition. If necessary, the filter 13 can be fixed by welding or the like to the end portion of the liquid suction nozzle 5h serving as a communication path inlet (liquid suction port) to the suction side volume chamber. The filter 13 can prevent foreign matter from entering the pump. In the internal gear pump of the first invention of the present application, the configuration of the trochoid-containing recess is not limited to the configuration shown in FIG. This is economical because the trochoid-containing recess can be formed without machining by injection molding.

Another embodiment of the internal gear pump according to the first invention of the present application will be described with reference to FIG. FIG. 3A is an axial sectional view of the internal gear pump, and FIG. 3B is an enlarged view around the seal surface of the casing in the internal gear pump. As shown in FIGS. 3A and 3B, the internal gear pump 1 has an annular groove 5f in a portion that seals the outer periphery of the trochoid-receiving recess 5a, and a seal ring 12 is provided in the groove 5f. Is assembled. The other configuration is the same as that of the internal gear pump shown in FIG. As shown in FIG. 3 (b), the seal surface 5d is a surface continuous from the inner surface 5b of the trochoid-containing recess 5a, and is in close contact with the surface of the cover to primarily seal the trochoid-containing recess 5a. Yes. The height position of the end surface 7a on the cover side of the bush 7 is higher than the bush forming surface 5e around the bush of the casing 5 as viewed from the bottom surface 5c with respect to the bottom surface 5c of the trochoid receiving recess 5a, and ( 2) The position is lower than the seal surface 5d around the recess of the casing 5.

In the internal gear pump of FIG. 3, in addition to this seal structure, a seal ring 12 is assembled, and the trochoid accommodating recess 5 a is secondarily sealed from the seal ring 12. For this reason, the sealing property of the trochoid accommodation recessed part 5a can be ensured more stably, and a safety factor becomes higher. Even when the seal ring 12 is provided, the amount of protrusion of the bush in the seal structure is the same. That is, even in the form of FIG. 3, the projection amount h ₁ from the bushing forming surface 5e of the end face 7a of the bush 7, the difference h ₂ between the height of the sealing surface 5d of the height and the casing 5 of the end face 7a of the bush 7, respectively For example, it is set to 0.01 mm to 0.3 mm.

The material of the seal ring is not particularly limited, and a rubber material that matches the application and use environment such as hydrogenated nitrile rubber, fluorine rubber, and acrylic rubber may be selected. For example, a scroll compressor of an air conditioner is required to have heat resistance and oil resistance of about −30 to 120 ° C. Therefore, it is preferable to use hydrogenated nitrile rubber (H—NBR system).

The resin composition forming the casing is made of a synthetic resin that can be injection-molded as a base resin. Examples of the base resin include thermoplastic polyimide resin, polyether ketone resin, polyether ether ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, polyamideimide resin, polyamide (PA) resin, and polybutylene terephthalate (PBT). Examples of the resin include polyethylene terephthalate (PET) resin, polyethylene (PE) resin, polyacetal resin, and phenol resin. Each of these resins may be used alone or a polymer alloy in which two or more kinds are mixed. Among these heat resistant resins, it is particularly preferable to use a PPS resin because the molded body is excellent in creep resistance, load resistance, wear resistance, chemical resistance, and the like.

Glass fiber, carbon fiber, or inorganic filler effective for high strength, high elasticity, high dimensional accuracy, imparting wear resistance and removing anisotropic injection molding shrinkage, alone or in combination as appropriate Is preferred. In particular, the combined use of glass fiber and inorganic filler is excellent in economic efficiency and excellent in friction and wear characteristics in oil.

In the first invention of the present application, it is particularly preferable to use a resin composition in which a linear PPS resin is used as a base resin and glass fibers and glass beads are blended as a filler. With this configuration, the oil resistance and chemical resistance are excellent, and the toughness is excellent. By removing the anisotropy of the injection molding shrinkage, the warpage of the flange portion is small, and the dimensional accuracy is greatly improved. In addition to this configuration, by omitting a rubber seal ring as shown in FIG. 2, it can be used suitably even in a high temperature atmosphere exceeding 120 ° C.

The means for mixing and kneading these raw materials is not particularly limited, and the powder raw material is dry-mixed with a Henschel mixer, ball mixer, ribbon blender, Redige mixer, Ultra Henschel mixer, etc., and further biaxially extruded. It is possible to obtain a molding pellet by melt-kneading with a melt extruder such as a machine. In addition, a side feed may be used for charging the filler when melt kneading with a twin screw extruder or the like. A casing is formed by injection molding using the molding pellets. At the time of molding, a metal bush is disposed in the mold and integrated by composite molding. At the time of molding, the mold shape and molding conditions are set so that the above relationships (1) and (2) are satisfied after molding in the bush and the casing.

In the internal gear pump of the first invention of the present application, the cover can be made of the above-mentioned metal (iron, stainless steel, sintered metal, aluminum alloy, etc.) or resin (similar to the casing), It may be a composite molded product of metal and resin. In addition, it is preferable to use a sintered metal (iron-based, copper-iron-based, copper-based, stainless-based, etc.) for the outer rotor and inner rotor, and iron is particularly preferable from the viewpoint of price. However, a trochoid pump that pumps water, chemicals, or the like may employ a stainless steel type that has a high rust prevention capability.

An embodiment of the internal gear pump according to the second invention of the present application will be described with reference to FIG. FIG. 5 is an axial sectional view of the internal gear pump. As shown in FIG. 5, the internal gear pump 41 includes a trochoid 44 in which an inner rotor 43 is accommodated in an annular outer rotor 42, a trochoid accommodating portion 46 that rotatably accommodates the trochoid 44, and the trochoid accommodating portion. A casing 45 joined to and supported by the outside of 46 is provided. The trochoid accommodating portion 46 includes a main body portion 47 having a cylindrical inner side surface 47 b and a flat plate-like inner bottom surface 47 c, and a lid portion 48 that closes the opening portion 47 a of the main body portion 47. A drive shaft 49 is coaxially fixed to the center of rotation of the inner rotor 43. The drive shaft 49 is supported by a bearing (not shown) provided in the casing 45 or the like. The lid 48 and the casing 45 have an opening in a portion through which the drive shaft 49 passes. The internal gear pump 41 is fastened and fixed to a member (not shown) of the equipment body by a bolt through a bolt fixing hole 50 formed in the flange 45b of the casing 45.

The outer teeth of the inner rotor 43 are one less than the inner teeth of the outer rotor 42, and the inner rotor 43 is housed in the outer rotor 42 in an eccentric state in which the outer teeth are inscribed in mesh with the inner teeth. Between the partition points where the rotors are in contact with each other, the suction-side and discharge-side volume chambers are formed according to the rotational direction of the trochoid 44. A suction port communicating with the suction-side volume chamber and a discharge port communicating with the discharge-side volume chamber are formed on the inner bottom surface 47 c of the main body 47 of the trochoid accommodating portion 46 of the casing 45.

In the internal gear pump 41, the trochoid 44 is rotated by the drive shaft 49, whereby the liquid is sucked from the suction port into the suction side volume chamber where the volume increases and becomes negative pressure. The suction-side volume chamber changes to a discharge-side volume chamber in which the volume decreases and the internal pressure increases as the trochoid 44 rotates, and the sucked liquid is discharged from the discharge-side volume chamber to the discharge port. The pumping action is continuously performed by the rotation of the trochoid 44, and the liquid is continuously pumped. Furthermore, due to the liquid sealing effect in which the sealing performance of each volume chamber is enhanced by the sucked liquid, the differential pressure generated between the volume chambers is increased, and a large pumping action is obtained.

The trochoid container 46 (main body 47 and lid 48) is made of sintered metal, and the casing 45 is an injection-molded body of a resin composition. The trochoid container 46 and the casing 45 are integrated (insert molding) by composite molding by disposing the trochoid container 46 in a mold when the casing 45 is injection molded. In terms of the structure, a part of the resin constituting the casing 45 enters into a part of the sintered pores on the outer surface of the trochoid accommodating portion that is a sintered body, and is firmly joined by the anchor effect. is there.

In the form shown in FIG. 5, the casing 45 is formed so as to cover not only the main body 47 of the trochoid accommodating part 46 but also the lid part 48. In order to achieve this form, at the time of manufacturing, first, the inner rotor 43 and the outer rotor 42 are combined and inserted into the main body 47 of the trochoid housing 46 from the opening 47a side, and then the lid 48 is closed to include the rotor. It is assumed that the trochoid accommodating part 46 is. The casing 45 can be formed so as to cover the lid portion 48 by arranging this in an injection mold and performing the above-described composite molding. With this structure, it is possible to prevent the lid 48 from being detached from the main body 47.

Examples of the sintered metal material that can be used for forming the trochoid housing 46 include iron-based, copper-iron-based, copper-based, and stainless-based materials. Since the price is low and the adhesiveness with the resin casing is excellent, it is preferable to employ a sintered metal whose main component is iron (which may include copper). Moreover, higher mechanical strength can be obtained by employing a sintered metal whose main component is iron. In addition, since copper is inferior to adhesiveness (adhesiveness) with resin rather than iron, when copper is included, the content of copper is preferably 10% by weight or less. More preferably, the copper content is 5% by weight or less. In addition, in the trochoid pump which pumps water, a chemical | medical solution, etc., it is preferable to employ | adopt stainless steel etc. with a high rust prevention capability.

It is preferable to use a sintered metal that is not impregnated with oil for the sintered metal that constitutes the trochoid housing 46. Moreover, when using oil in the process of shaping | molding or re-pressure shaping (sizing) of a sintered metal, it is preferable to set it as the non-oil-containing sintered metal which removed oil by solvent washing etc. 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 has the required density to ensure the strength of the trochoid housing part, and the surface irregularities for firmly attaching the resin casing to the trochoid housing part (Sintered pores) can be secured.

The adjustment of the accommodating portion depth in the trochoid accommodating portion 46 can be performed by planarizing the axial cross section of the cylindrical side wall of the main body 47, and can be easily adjusted by machining.

Since the casing 45 is an injection-molded body of the resin composition, and the discharge amount design can be adjusted only by the trochoid housing part 46, the degree of freedom in designing the pump shape and the like is widened. Further, the liquid suction nozzle 45a can be formed integrally with the casing 45 with a resin composition. If necessary, a foreign matter mixing filter may be fixed to the end of the liquid suction nozzle 45a serving as a communication path inlet (liquid suction port) to the suction side volume chamber by welding or the like.

The resin composition forming the casing 45 is made of a synthetic resin that can be injection-molded as a base resin. Examples of the base resin include thermoplastic polyimide resin, polyether ketone resin, polyether ether ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, polyamideimide resin, polyamide (PA) resin, and polybutylene terephthalate (PBT). Examples of the resin include polyethylene terephthalate (PET) resin, polyethylene (PE) resin, polyacetal resin, and phenol resin. Each of these resins may be used alone or a polymer alloy in which two or more kinds are mixed. Among these heat resistant resins, it is particularly preferable to use a PPS resin because the molded body is excellent in creep resistance, load resistance, wear resistance, chemical resistance, and the like.

In the second invention of the present application, it is particularly preferable to use a resin composition in which a linear PPS resin is used as a base resin and glass fibers and glass beads are blended as a filler. With this configuration, the oil resistance and chemical resistance are excellent, and the toughness is excellent. By removing the anisotropy of the injection molding shrinkage, the warpage of the flange portion is small, and the dimensional accuracy is greatly improved. In addition to this configuration, it has an independent trochoid housing and does not require a conventional rubber seal ring, so it can be suitably used even in a high temperature atmosphere exceeding 120 ° C. Become.

The means for mixing and kneading these raw materials is not particularly limited, and the powder raw material is dry-mixed with a Henschel mixer, ball mixer, ribbon blender, Redige mixer, Ultra Henschel mixer, etc., and further biaxially extruded. It is possible to obtain a molding pellet by melt-kneading with a melt extruder such as a machine. In addition, a side feed may be used for charging the filler when melt kneading with a twin screw extruder or the like. A casing is formed by injection molding using the molding pellets. At the time of molding, the entire trochoid housing part or only the main body part is arranged in the mold and integrated by composite molding.

In the internal gear pump of the second invention of the present application, it is preferable to use a sintered metal (iron-based, copper-iron-based, copper-based, stainless-based, etc.) for the outer rotor and the inner rotor in the same manner as the trochoid accommodating portion.

Another embodiment of the internal gear pump according to the second aspect of the present invention will be described with reference to FIG. FIG. 6 is an axial sectional view of the internal gear pump. As shown in FIG. 6, the internal gear pump 41 has a structure in which the lid portion 48 is exposed from the casing 45. The other configuration is the same as that of the internal gear pump shown in FIG. In the form shown in FIG. 6, after the body portion 47 and the casing 45 of the trochoid accommodating portion 46 are combined, each rotor can be inserted into the body portion 47 and the lid portion 48 can be closed. Similarly to the case of FIG. 5, the trochoid accommodating portion 46 including the rotor may be assembled and then molded with the casing. By fixing the main body portion 47 and the lid portion 48 by caulking, a bolt tightening step or the like is unnecessary and simple, and can be firmly fixed.

Another embodiment of the internal gear pump according to the second invention of the present application will be described with reference to FIG. FIG. 7 is an axial sectional view of the internal gear pump. As shown in FIG. 7, the internal gear pump 41 has a structure in which a lid portion 48 and a casing 45 are fastened by bolts 51. Thereby, in the trochoid accommodating part 46, the main-body part 47 and the cover part 48 are closely_contact | adhered. The other configuration is the same as that of the internal gear pump shown in FIG. If necessary, in the flange portion 45b of the casing 45, a metal bush may be interposed in the bolt fixing hole 50, and bolt fastening may be performed through the bush. In the form shown in FIG. 7, the rotor 47 is inserted into the main body 47 after the main body 47 and the casing 45 of the trochoid container 46 are combined. Then, it can manufacture in the procedure which bolts the cover part 48 with respect to the casing 45. FIG.

The above description has been made with reference to FIGS. 5 to 7, but the configuration of the internal gear pump of the second invention of the present application is not limited to this. In any form, the trochoid housing part is a separate part from the casing, and the casing is compounded around the trochoid housing part that has been manufactured by processing the housing part depth with high precision beforehand, so that both members are joined together. It has the structure. As a result, there is no variation in the discharge amount among the individual units, and the internal gear pump has a stable discharge capability.

The internal gear pumps according to the first and second inventions of the present application can be used as an internal gear pump (trochoid pump) that pumps liquid such as oil, water, and chemicals. It can be suitably used as a pump for supplying liquid to the sliding portion of a scroll compressor for an electric water heater, room air conditioner, or car air conditioner.

DESCRIPTION OF SYMBOLS 1 Internal gear pump 2 Outer rotor 3 Inner rotor 4 Trochoid 5 Casing 6 Cover 7 Bush 8 Metal plate 9 Bolt 10 Drive shaft 11 Fixing plate of apparatus main body 12 Seal ring 13 Filter 41 Internal gear pump 42 Outer rotor 43 Inner rotor 44 Trochoid 45 Casing 46 Trochoid housing part 47 Body part 48 Lid part 49 Drive shaft 50 Bolt fixing hole 51 Bolt

Claims

An inner rotor having a plurality of external teeth is rotatably accommodated in an outer rotor having a plurality of internal teeth in a state where the external teeth mesh with the internal teeth and is eccentric. An internal gear pump having a trochoid in which 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,
A casing having a recess for accommodating the trochoid, and a cover for closing the recess of the casing, wherein the casing is an injection-molded body of a resin composition,
The casing and the cover are bolted, and have a metal bush at the bolt fixing hole portion of the casing,
In the cross section of the joint between the casing and the cover, the end surface position of the bush on the cover side is higher than the bush forming surface around the bush of the casing when viewed from the bottom of the recess, and the recess of the casing An internal gear pump characterized by being equal to or lower than a surrounding sealing surface.
The internal gear pump according to claim 1, wherein the sealing surface is a surface continuous from an inner surface of the recess of the casing and seals the recess in close contact with the surface of the cover.
The internal gear pump according to claim 1, wherein a seal ring is not interposed at a joint portion between the casing and the cover.
The internal gear pump according to claim 1, wherein an inner side surface of the recess of the casing is made of an injection-molded body of the resin composition, and a bottom surface of the recess is made of a metal body.
2. The resin composition according to claim 1, wherein the resin composition comprises a polyphenylene sulfide resin as a base resin and is blended with at least one selected from glass fibers, carbon fibers, and inorganic fillers. The described internal gear pump.
An inner rotor having a plurality of external teeth is rotatably accommodated in an outer rotor having a plurality of internal teeth in a state where the external teeth mesh with the internal teeth and is eccentric. An internal gear pump having a trochoid in which 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,
A trochoid housing made of sintered metal that houses the trochoid, and a casing joined to the outside of the trochoid housing,
The casing is an injection-molded body of a resin composition, and the trochoid housing part and the casing are partly joined into the sintered pores on the outer surface of the trochoid housing part. Features an internal gear pump.
The internal gear pump according to claim 6, wherein the trochoid housing part comprises a main body having a cylindrical inner side surface and a flat inner bottom surface, and a lid for closing an opening of the main body.
The internal gear pump according to claim 7, wherein the lid portion is fixed by caulking to the opening portion of the main body portion.
The trochoid container and the casing are joined by joining a part of the casing into sintered pores on the outer surface of the main body and the lid in the trochoid container. The internal gear pump according to claim 7.