WO2019107537A1

WO2019107537A1 - Internal gear pump

Info

Publication number: WO2019107537A1
Application number: PCT/JP2018/044154
Authority: WO
Inventors: 智和園嵜; 洋赤井; 圭服部; 伊藤　貴之
Original assignee: Ntn株式会社
Priority date: 2017-11-30
Filing date: 2018-11-30
Publication date: 2019-06-06

Abstract

Provided is an internal gear pump wherein a casing and a cover can be easily positioned to each other when the casing and the cover are mounted to each other, and separation or dislodgement of both members can be prevented. In this internal gear pump 1, a casing 5 and/or cover 6 is a formed body formed from a resin composite or the like. The casing 5 and the cover 6 are affixed to each other by fitting a plurality of protrusions protruding from one of the members, to the other member. The protrusions are the portions of metallic bushes 9, which protrude from the casing 5, the metallic bushes 9 being affixed to the casing 5, and the casing 5 and the cover 6 are integrated by bolts 13 inserted in the metallic bushes 9 which straddle both the members.

Description

Internal gear pump

The present invention relates to an internal gear pump (trochoid (registered trademark, the same hereinafter) pump) for pumping a fluid such as oil, water, or chemical solution, and in particular, an internal gear pump used in the industrial machine field, for example, a compressor for air conditioning. About.

In the internal gear pump, an outer rotor and an inner rotor having a trochoidal tooth profile are housed in a sealed state in a casing, and with the rotation of the drive shaft, the inner rotor fixed to the drive shaft and the outer rotor rotate to suck in liquid. It is a pump that acts to discharge. In recent years, a pump having a resin-made casing has been known as a pump of this type that can reduce the number of machining steps and can be manufactured at low cost (see Patent Document 1).

The structure of this type of internal gear pump will be described based on FIG. FIG. 5 is a cross-sectional view of a conventional internal gear pump. As shown in FIG. 5, 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 25 a formed in a flanged cylindrical casing 25. A cover 26 for closing the trochoid receiving recess 25 a is fixed to the casing 25. Further, a drive shaft 27 which is rotated by a drive source (not shown) is fixed to pass through the shaft center of the inner rotor 23.

The cover 26 is made of sintered metal, and the casing 25 is an injection-molded product manufactured by injection molding using a resin composition. The casing 25 and the cover 26 are fastened and fixed to the fixed plate 30 of the actual machine by bolts 29 passed through a metal bush 28 provided on the casing 25. The casing 25 and the cover 26 seal the trochoid receiving recess 25a in a flat planar shape.

JP 2014-51964 A

As described above, such an internal gear pump is bolt-fastened in a state in which the resin casing and the metal cover are superimposed when attached to the actual machine. Generally, since a resin molded product has low mechanical strength, the strength of the fastening portion is improved by insert molding the above-mentioned metal bush. However, the interface between the casing and the cover is a flat surface, and it is necessary to visually check displacement of bolt holes in the metal bush and the cover on the casing side and to align the position of the casing and the cover. In addition, there is a risk that the housing and the cover may separate and fall off during installation or transportation. In particular, when attaching to a real machine, depending on the mounting posture of the pump, it may easily fall off, and the workability may be reduced.

The present invention has been made to address such problems, and it is easy to align the casing and the cover at the time of assembly, and it is possible to prevent separation and removal of these two members, and further, if necessary. It is an object of the present invention to provide an internal gear pump with improved mechanical strength.

According to the internal gear pump of the present invention, an inner rotor having a plurality of outer teeth is rotatably accommodated in an outer rotor having a plurality of inner teeth, with the outer teeth meshing with the inner teeth and being eccentric. It is an internal gear pump in which a suction side volume chamber for sucking in liquid and a discharge side volume chamber for discharging liquid sucked in to the suction side volume chamber are formed between the internal teeth and the external teeth. A casing having a recess for receiving the outer rotor and the inner rotor; and a cover closing the recess of the casing, the casing and the cover including a plurality of projecting portions projecting from one member and the other It is characterized in that it is fitted in and fixed to a member.

It is characterized in that at least one member of the casing and the cover is formed of a molded body of a resin composition. Alternatively, at least one member of the casing and the cover is formed of a metal compact.

The casing and the cover are integrated by a fixing member which is passed through a metal bush which straddles both the members, and at least one of the projecting portions is formed on one member of the casing and the cover. It is characterized in that it is a protruding portion of a metal bush which is fixedly protruded from a member.

In the embodiment using the molded product of the resin composition and the metal bush, the metal bush is a sintered metal bush, the molded product is an injection molded article of the resin composition, and the metal is molded. A bush is provided integrally with the injection molded body in one member of the casing and the cover at the time of the injection molding.

It is characterized in that at least one of the protruding portions is a claw portion protruding as a part of the molded body in one member of the casing and the cover.

The resin composition is characterized in that it is a resin composition comprising a polyphenylene sulfide (PPS) resin as a base resin, and at least one selected from glass fibers, carbon fibers, and inorganic fillers. .

In the internal gear pump according to the present invention, since the plurality of projections projecting from one member in the casing and the cover are engaged with and fixed to the other member, positioning during assembly is easy and Separating or falling off of both members can be prevented, and the workability is excellent.

When at least one member of the casing and the cover is a molded product of the resin composition, the positioning at the time of assembling the casing and the cover becomes easier by taking advantage of the characteristics of the resin composition. It can prevent separation and falling off, and is more excellent in workability.

In addition, when at least one member of the casing and the cover is a molded metal, while the mechanical strength between the casing and the cover is improved, the positioning at the time of assembling them is easy, and the two members are separated And can be prevented from falling off.

The casing and the cover are integrated by a fixing member passed through a metal bush straddling both the members, and at least one of the above-mentioned projecting parts projects from the member to one member of the casing and the cover. Since it is a projecting portion of the fixed metal bush, when assembling the casing and the cover, the projecting portion of the metal bush in one member is fitted with the fitting portion of the other member to the projecting portion By doing this, both members can be easily aligned. Further, the strength of the fastening portion between the casing and the cover can be improved by the metal bush, and the loosening of the fastening portion due to the creep deformation of the resin can be prevented.

In the embodiment in which at least one member of the casing and the cover is a molded product of a resin composition and a metal bush is used, the metal bush is a sintered metal bush and an injection molded body of one member of the casing and the cover The resin is inserted into the surface recess of the sintered metal of the bush, since the bush is disposed integrally in the mold at the time of injection molding, that is, the bush is disposed in the mold at the time of injection molding and integrated by composite molding. It is excellent in the joint strength of both members by the anchor effect. As a result, even when the bush is made to project long from an injection-molded article such as a casing, it is possible to prevent the bush from coming off during transportation or mounting.

Since the resin composition is a resin composition comprising a PPS resin as a base resin, and at least one selected from glass fiber, carbon fiber, and an inorganic filler, the resin composition is excellent in dimensional accuracy and toughness, It becomes easy to get the effect. Moreover, it is excellent in oil resistance and chemical resistance, and can be used even in a high temperature atmosphere exceeding 120 ° C. such as a compressor.

When at least one member of the casing and the cover is a molded product of a resin composition, at least one of the protrusions is a claw that protrudes as a part of the molded product, so that the claw is also a molded product made of resin It is easy to elastically deform, is excellent in toughness, and can prevent breakage and the like at the time of assembly.

When at least one member of the casing and the cover is a molded metal, since at least one of the protrusions is a claw projecting as a part of the molded product, the claw is also a molded metal made of metal. As a result, the mechanical strength is excellent, and breakage and the like can be prevented during assembly.

It is an assembly perspective view showing an example of an internal gear pump of the present invention. It is an axial sectional view of the internal gear pump of FIG. It is an assembly perspective view which shows the other example of the internal gear pump of this invention. It is a completion perspective view of the internal gear pump of FIG. It is an axial sectional view of the conventional internal gear pump.

According to the present invention, an inner rotor having a plurality of outer teeth is rotatably housed in an outer rotor having a plurality of inner teeth, with the outer teeth meshing with the inner teeth and being eccentric, The present invention relates to an internal gear pump having a trochoid in which a suction-side volume chamber for sucking in liquid and a discharge-side volume chamber for discharging the liquid sucked in to the suction-side volume chamber are formed therebetween. The internal gear pump has a casing having a recess for receiving an outer rotor and an inner rotor, which constitute a trochoid, and a cover for closing the recess of the casing.

The internal gear pump of the present invention is characterized in that the casing and the cover are fixed by fitting a plurality of projecting portions projecting from one member to the other member. Examples of the protrusion include a form using a metal bush fixed to a resin-made casing, and a form using a claw part provided on a resin-made or metal-made casing or cover.

An internal gear pump in the form of utilizing a metal bush will be described based on FIGS. 1 and 2. FIG. 1 is an assembled perspective view showing an example of an internal gear pump, and FIG. 2 is an axial sectional view of the internal gear pump.
As shown in FIGS. 1 and 2, the internal gear pump 1 includes a trochoid 4 in which the inner rotor 3 is accommodated in the annular outer rotor 2, and a circular recess (trochoid accommodation recess) that rotatably accommodates the trochoid 4. A pump casing 5a in which 8 is formed, a suction casing 5b in which a liquid suction portion 5c is formed, and a cover 6 for closing the trochoid receiving recess 8 of the pump casing 5a. The casing 5 is composed of two members, a pump casing 5a and a suction casing 5b. The cover 6 has a shape that matches the outer shape of the upper surface of the casing 5 in which the trochoid receiving recess 8 is opened. Three metal bushes 9 are fixed to the suction casing 5b. As shown in FIG. 2, the pump casing 5a, the suction casing 5b and the cover 6 are fixed to a fixed plate of the actual machine by bolts 13 which are fixing members passed through metal bushes 9 straddling them, and integrated. It is done. The fixing member is not limited to the bolt 13 as long as it can fix each member, and may be, for example, a screw or a pin. Also, the internal gear pump 1 has a drive shaft 11 coaxially fixed to the rotation center of the inner rotor 3.

The outer teeth of the inner rotor 3 are smaller by one 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 contact and mesh with the inner teeth. Depending on the rotational direction of the trochoid 4, volume chambers on the suction side and the discharge side are formed between the dividing points at which the rotors are in contact with each other. The bottom 8a of the trochoid receiving recess 8 of the casing 5 is formed with a liquid flow path including a suction port communicating with the suction-side volume chamber and a discharge port communicating with the discharge-side volume chamber. The liquid is pressure-fed from a discharge port to a compression unit (not shown) in the upper part of the drawing through a discharge flow path in the center of the drive shaft 11.

In the internal gear pump 1, the trochoid 4 is rotated by the drive shaft 11 to increase the volume to a negative pressure, whereby the liquid is sucked into the pump through the suction port. 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 4, and the suctioned 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, the fluid sealing effect in which the sealing performance of each volume chamber is enhanced by the inhaled liquid increases the differential pressure generated between the volume chambers, and a large pumping action is obtained.

In the internal gear pump of the present invention, at least one member of the casing and the cover is a molded body (resin body) of a resin composition. This makes it possible to reduce the number of machining steps and to manufacture at low cost. The internal gear pump according to the present invention, in a configuration employing such a resin casing or the like, further facilitates alignment at the time of assembling the casing and the cover, and prevents separation and separation of these two members. is there. In the embodiment of FIGS. 1 and 2, substantially the whole of the casing 5 and the cover 6, that is, the cover 6, the pump casing 5a and the suction casing 5b are made of resin and they are integrated by the metal bush 9 and the bolt 13. ing. The member for fixing at least the metal bush 9 may be a resin, and for example, the cover 6 may be made of metal (iron, stainless steel, sintered metal, aluminum alloy or the like).

As shown in FIGS. 1 and 2, the metal bush 9 is fixed to the flange portion 5d of the suction casing 5b. By fitting the projecting portion of the metal bush 9 from the suction casing 5b to the fitting portion 6a of the pump casing 5a and the fitting portion 6a of the cover 6, alignment of these members can be facilitated. Further, by interposing the metal bush 9, even if one or both of the casing 5 and the cover 6 are made of resin body, strength can be improved at the fastening portion of both members, and fastening due to creep deformation of the resin It also prevents loose parts. Furthermore, the assembly (casing and cover) of the temporary assembly can be prevented from separating or falling off during installation or transportation. In addition, foreign matter can be prevented from entering the rotor portion.

In addition, it is preferable that the length of the metal bush 9 is adjusted and the end of the metal bush 9 when assembled is a length that does not protrude from the upper end surface 6 b of the fitting portion 6 a of the cover 6. More preferably, the tip of the metal bush 9 is shaped so as to be recessed from the upper end surface 6 b of the fitting portion 6 a of the cover 6. Thereby, interference between the fixed plate of the actual machine and the metal bush 9 can be prevented.

The metal bush 9 can be made of any metal such as iron, stainless steel, sintered metal or the like, and is particularly preferably made of sintered metal. Since the metal bush is made of sintered metal and is compound-formed (insert molding) with the suction casing, the resin enters into the surface concave portion of the sintered metal of the bush, so that it is strongly joined by the anchor effect.

In the pump casing, it is preferable that the inner side surface of the trochoid receiving recess be made of a resin and the bottom surface of the recess be made of a metal. As shown in FIG. 2, the pump casing 5 a is in sliding contact with the outer rotor 2 and the inner rotor 3 at the bottom surface 8 a and the inner side surface 8 b of the trochoid receiving recess 8. By making the inner side surface 8 b of the trochoid receiving recess 8 a resin body, the friction and wear characteristics with the outer rotor 2 are excellent. Further, the bottom surface 8 a of the trochoid receiving recess 8 is formed of a disk-shaped metal plate 7 integrated with the pump casing 5 a by composite molding. Thereby, as compared with the case where the bottom surface 8 a is formed of resin, the flatness is excellent, and the variation of the discharge performance can be suppressed. As the metal plate 7, a sintered metal body or a molten metal body (sheet metal pressed product) can be employed.

By forming the casing 5 into two members of the pump casing 5a and the suction casing 5b, composite molding (insert molding) of the metal plate 7 as described above is facilitated. In the present invention, even when the casing is separated into a plurality of members and the number of parts is increased as described above, the fitting structure using the plurality of projecting portions facilitates the alignment and is excellent in the assembling property. In addition, a liquid suction portion 5c is provided in the suction casing 5b. If necessary, the filter 14 can be fixed by welding or the like to an end portion of the liquid suction portion 5c which is an inlet (liquid suction port) of the communication passage to the suction side volume chamber. The filter 14 can prevent the entry of foreign matter into the pump.

Further, in the pump casing 5a, a groove is provided on the outer peripheral portion of the trochoid receiving recess 8, and the seal ring 12 is assembled to the groove. By assembling the seal ring 12, it is possible to prevent the liquid from leaking from the mating surface of the pump casing 5a and the cover 6, to suppress the variation in the discharge amount, and the safety factor is increased. The seal ring 12 may be omitted if sufficient sealing performance can be ensured at the joint surfaces of the casing and the cover.

An internal gear pump in the form of utilizing the claws will be described based on FIGS. 3 and 4. FIG. 3 shows an assembled perspective view showing another example of the internal gear pump, and FIG. 4 shows a completed perspective view of the internal gear pump. As shown in FIGS. 3 and 4, the internal gear pump 1 ′ includes a trochoid 4 in which the inner rotor 3 is accommodated in the annular outer rotor 2, a casing 5 in which the trochoid accommodation recess 8 is formed, and the trochoid accommodation recess 8. And a cover 6 for closing the cover. The cover 6 has a shape that matches the outer shape of the upper surface of the casing 5 in which the trochoid receiving recess 8 is opened. The casing 5 is made of resin. The casing 5 and the cover 6 are fixed to and integrated with a fixed plate of the actual machine by bolts (not shown) passed through the metal bush 9 fixed to the casing 5. The basic configuration of the other pumps is the same as that shown in FIGS. 1 and 2.

In this form, the metal bush 9 is not fitted up to the cover 6. On the other hand, the casing 5 is provided with four claws 10 projecting from the casing. The claws 10 are integral with the casing 5 and formed at the same time as molding of the resin casing 5. As shown in FIG. 4, at the time of assembly, the claw portion 10 is fitted (engaged) so as to hold the outer peripheral portion of the cover 6, which enables easy alignment. In addition, since the claw portion is made of resin, it is easily elastically deformed, has excellent toughness, and can be prevented from being damaged during assembly. The shape and the number of the claws 10 are not particularly limited as long as the two members can be aligned.

In each of the above embodiments, the resin composition that forms the casing and the cover mainly uses a synthetic resin that can be injection-molded as a base resin. As the base resin, for example, PPS resin, thermoplastic polyimide resin, polyether ketone resin, polyether ether ketone (PEEK) resin, polyamide imide resin, polyamide (PA) resin, polybutylene terephthalate (PBT) resin, polyethylene terephthalate (PET) resin, polyethylene (PE) resin, polyacetal resin, phenol resin and the like. Each of these resins may be used alone or in combination of two or more kinds. Among these heat resistant resins, it is particularly preferable to use a PPS resin because it is excellent in creep resistance, load resistance, abrasion resistance, chemical resistance and the like of the molded body.

Glass fiber, carbon fiber, or inorganic filler effective for high strength, high elasticity, high dimensional accuracy, wear resistance and anisotropy removal of injection molding shrinkage alone or in combination Is preferred. In particular, the combination of glass fiber and inorganic filler is excellent in economical efficiency and excellent in friction and wear characteristics in oil.

In the present invention, 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 thereto. With this configuration, since both oil resistance and chemical resistance are excellent, toughness is excellent, warpage is small due to anisotropic removal of injection molding shrinkage, and dimensional accuracy is also greatly improved. Particularly effective.

A casing or a cover is formed by injection molding using molding pellets obtained from these various raw materials. In the case of using the members shown in the embodiments of FIGS. 1 and 2, when forming the suction casing, the above-mentioned metal bush is disposed in the mold and integrated by composite molding. Further, at the time of forming the pump casing, the above-described metal plate is disposed in a mold and integrated by composite forming.

Also, the casing or the cover can be formed, for example, as a die-cast product. As a material, for example, a low melting point alloy such as an aluminum alloy is preferable. As a die-cast product made of aluminum alloy, for example, an Al-Si alloy (ADC1), an Al-Si-Mg alloy (ADC3), an Al-Mg alloy (ADC5, etc.) defined in JIS H 5302 (2006) etc. ADC6), Al-Si-Cu based alloys (ADC10, ADC10Z, ADC12, ADC12Z, ADC14) and the like.

The casing or the cover can also be shaped, for example, as a sintered metal article. As a sintered metal, an iron-based sintered metal etc. are preferable. More specifically, for example, an iron-based sintered metal having a pearlite phase at least in a surface layer portion, and in which copper and tin are mixed to bond iron structures, is preferable. In this case, the iron structures are bonded with a copper-tin alloy. An example of the composition of this type of iron-based sintered metal will be described. Iron-based sintered metal containing 1 to 10% by weight (preferably 1 to 8% by weight) of copper, 0.5 to 2% by weight of tin, 0.1 to 0.5% by weight of carbon and the balance being iron It is. The blending ratio of tin to copper is 1/5 or more and 1 or less by weight. Most of copper and tin in iron-based sintered metals exist as copper-tin alloys, and almost no structure of copper alone or tin alone exists. For example, the ratio of the copper structure to the copper component in the sintered metal is 5% by weight or less, and the ratio of the tin structure to the tin component in the sintered metal is 0.1% by weight or less. The density of such a sintered metal product is preferably, for example, 6.6 g / cm ³ or more, preferably 6.8 g / cm ³ or more, for example, 8.0 g / cm ³ or less.

As a specific combination, for example, the casing is formed of the Al-Si-Cu-based aluminum alloy (ADC 12), and the cover is an iron-based sintered metal having a pearlite phase at least in the surface layer, or the Al-Si -A combination formed by molding a Cu-based die cast aluminum alloy (ADC 12) may be mentioned.

In the internal gear pump of the present invention, it is preferable to use a sintered metal (iron-based, copper-iron-based, copper-based, stainless-based, etc.) as the material of the outer rotor and inner rotor. Systems are preferred. In addition, in the trochoid pump which pumps water, a chemical | medical solution etc., what is necessary is just to employ | adopt stainless steel etc. with a high rustproof capability.

As mentioned above, although the case where a metal bush and a nail part were used as a projection part was explained based on each figure, an internal gear pump of the present invention is not limited to these. For example, both the metal bush and the claw may be used. In addition, it is possible to adopt an arbitrary structure in which a plurality of protrusions protruding from one member are fitted and fixed to the other member.

The internal gear pump of the present invention is easy to align at the time of assembling the casing and the cover, and can prevent separation and detachment of these two members, so that it is possible to pressure-feed liquids such as oil, water, and chemical solutions. It can be widely used as a contact gear pump (trochoid pump). For example, it can be used as a pump for supplying a liquid to the sliding part of a scroll type compressor for an electric water heater, a room air conditioner, or a car air conditioner using a fluorocarbon substitute or carbon dioxide as a refrigerant.

1 internal gear pump 2 outer rotor 3 inner rotor 4 trocoid 5 casing 5a pump casing 5b suction casing 5c liquid suction portion 5d flange portion 5e fitting portion (suction casing)
6 cover 6a mating part (cover)
6b upper end surface 7 metal plate 8 trochoidal housing recess 8a bottom surface 8b inner side surface 9 metal bush 10 claw portion 11 drive shaft 12 seal ring 13 bolt 14 filter

Claims

An inner rotor having a plurality of outer teeth is rotatably accommodated in an outer rotor having a plurality of inner teeth, with the outer teeth meshing with and eccentric to the inner teeth, and the inner tooth and the outer teeth An internal gear pump in which a suction side volume chamber for drawing in liquid and a discharge side volume chamber for discharging the liquid drawn in to the suction side volume chamber are formed therebetween,
A casing having a recess for receiving the outer rotor and the inner rotor, and a cover closing the recess of the casing;
The internal gear pump, wherein the casing and the cover are fixed by fitting a plurality of projections projecting from one member to the other member.
The internal gear pump according to claim 1, wherein at least one member of the casing and the cover is a molded body of a resin composition.
The casing and the cover are integrated by a fixing member passed through a metal bush straddling both members,
The internal gear pump according to claim 1, wherein at least one of the protrusions is a protrusion of a metal bush which is fixed to one member of the casing and the cover so as to protrude therefrom.
At least one member of the casing and the cover comprises a molded body of a resin composition,
The casing and the cover are integrated by a fixing member passed through a metal bush straddling both members,
The internal gear pump according to claim 1, wherein at least one of the protrusions is a protrusion of a metal bush which is fixed to one member of the casing and the cover so as to protrude therefrom.
The metal bush is a sintered metal bush, and the molded body is an injection molded body of the resin composition,
5. The internal gear pump according to claim 4, wherein the metal bush is integrally formed on the injection molded body in one of the casing and the cover at the time of injection molding.
The at least one of the said protrusion part is the nail | claw part which protruded as a part of the said molded object in one member of the said casing and the said cover, or the said injection molded object, Internal gear pump.
The resin composition is a resin composition comprising a polyphenylene sulfide resin as a base resin and to which at least one selected from glass fiber, carbon fiber, and an inorganic filler is blended. Or the internal gear pump of Claim 4.
The internal gear pump according to claim 1, wherein at least one member of the casing and the cover is a molded body of metal.
The casing and the cover are integrated by a fixing member passed through a metal bush straddling both members,
9. The internal gear pump according to claim 8, wherein at least one of the protrusions is a protrusion of a metal bush which is fixed to one member of the casing and the cover so as to protrude therefrom.
9. The internal gear pump according to claim 8, wherein at least one of the protrusions is a claw that protrudes as a part of the molded body in one member of the casing and the cover.