WO2018199152A1 - Internal gear pump and internal gear pump unit - Google Patents

Abstract

Provided is an internal gear pump in which, while a cover and a casing are made of a resin, no breakage occurs when the cover and casing are fastened, and which demonstrates stable discharging performance. Provided is an internal gear pump 1 wherein at least portions of a casing 5 and a cover 6 which are to be joined together are each formed from an injection molding body of a resin composition, the casing 5 and the cover 6 are fixed, the casing 5 and the cover 6 are in contact with each other without any gap in a bolt fixing portion 13 of the two members, a recess closing portion 12 between the casing 5 and the cover 6 has a gap between the two members, and this gap is sealed with a rubber ring 10 provided on the outer periphery of a trochoid accommodating recess 7.

Description

Internal gear pump and internal gear pump unit

The present invention relates to an internal gear pump (trochoid pump) and an internal gear pump unit for pumping liquids such as oil, water, and chemicals, and more particularly to an internal gear pump used in the industrial machinery field, for example, an air conditioning compressor, and The present invention relates to an internal gear pump unit.

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, pumps having a resin casing have been known as this type of pump, which can reduce machining processes and can be manufactured at low cost (see Patent Documents 1 and 2).

Referring to FIG. 19, the structure of this type of internal gear pump will be described. FIG. 19 is a cross-sectional view of a conventional internal gear pump. As shown in FIG. 19, the pump 161 mainly includes a trochoid 164 in which an inner rotor 163 having a plurality of external teeth is accommodated in an annular outer rotor 162 having a plurality of internal teeth. The trochoid 164 is rotatably accommodated in a circular trochoid accommodating recess 167 formed in a cylindrical casing 165 with a flange. A cover 166 that closes the trochoid-containing recess 167 is fixed to the casing 165. A drive shaft 172 that is rotated by a drive source (not shown) passes through and is fixed to the axis of the inner rotor 163.

The cover 166 is made of sintered metal, and the casing 165 is an injection-molded body manufactured by injection molding using a resin composition. The casing 165 and the cover 166 are fastened and fixed to the fixing plate 171 of the apparatus main body by bolts 169 passed through the respective bolt holes 168. The casing 165 and the cover 166 have a flat shape and seal the trochoid-containing recess 167. A rubber ring (O-ring) 170 is assembled in a groove formed on the outer periphery of the concave portion of the casing 165 on the joint surface (matching surface) between the casing 165 and the cover 166. This rubber ring 170 is used to seal the trochoid-containing recess 167 and prevents liquid from leaking from the mating surface of the casing 165 and the cover 166.

In such a structure, suction-side and discharge-side volume chambers are formed according to the rotational direction of the trochoid 164 between the partition points where the rotors contact each other. When the drive shaft 172 rotates and the inner rotor 163 rotates, the outer teeth mesh with the inner teeth of the outer rotor 162, whereby the outer rotor 162 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 164, and the sucked liquid is discharged from the discharge port to the discharge port.

A liquid suction nozzle 165a is provided as a communication passage for supplying liquid to the suction side volume chamber, and the tip of the nozzle 165a is immersed in the liquid reservoir. The casing 165 includes the above-described trochoid accommodating recess 167 and the liquid suction nozzle 165a, and is integrally formed.

JP 2014-51964 A JP2015-113810A

As described above, in the conventional example, the cover is a sintered metal product, but it is also desired that the cover be made of resin in order to reduce the cost. However, when the casing and the cover are resin injection-molded products, the dimensional accuracy varies. In order for the internal gear pump to function, it is necessary to seal the trochoid housing recess, which is the rotor housing. When the trochoid-receiving recess is sealed when the internal gear pump is attached to the counterpart device with a bolt or the like, a gap is generated in the mating surface between the casing flange and the cover flange due to variations in dimensional accuracy. If a bolt or the like is tightened in a state where there is a gap, stress is generated, and the casing and the cover may be damaged. In addition, if the tightening is weak, the sealing performance cannot be maintained, which may adversely affect the discharge performance.

The present invention has been made to cope with such problems, and provides an internal gear pump that is made of a resin and has a cover and a casing that are not damaged when fastened, and that has a stable discharge performance. The purpose is to do.

In the internal gear pump of the present invention, 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 are 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 between the inner teeth and the outer teeth And a casing having a recess (trochoid receiving recess) for accommodating the trochoid, and a cover for closing the recess of the casing, wherein the casing and the cover are each provided with at least a portion joined to each other. It consists of an injection-molded body of a resin composition, the casing and the cover are fixed, and the fixed part between the casing and the cover is in contact with both members without a gap. The recess closing portion between the casing and the cover has a gap between both members, and the gap is sealed with an elastically deformable elastic member provided on the outer periphery of the recess. To do.

The elastically deformable elastic member is a rubber ring.

Each of the casing and the cover has a flange portion on the outer peripheral portion, and the cover is fitted with the casing at a step portion on the inner peripheral side of the flange portion to form the recessed portion closing portion. The fixing part is configured by being fixed to a flange part of the casing. In particular, the casing and the cover are fixed by bolts.

The cover is structured to receive a thrust load of a drive shaft fixed to the inner rotor.

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 (PPS) resin as a base resin and blended with at least one selected from glass fibers, carbon fibers, and inorganic fillers. .

An internal gear pump unit comprising the internal gear pump of the present invention and a liquid suction nozzle having a tip immersed in the liquid reservoir and forming a part of a communication path to the suction-side volume chamber of the liquid. The internal gear pump unit includes a pump body having the trochoid and the casing, and a liquid suction part having the liquid suction nozzle. The casing of the pump body and the liquid The suction part is characterized in that the liquid communication path provided in each of the suction parts is connected and detachably fixed by a fixing means.

The fixing means includes a retaining ring that is fitted into a groove formed across the casing and the liquid suction portion at the fitting portion.

The casing is provided with a fitting recess, and the liquid suction portion is provided with a fitting projection corresponding to the recess, and the fitting recess and the fitting projection are combined, A circumferential groove is formed as the groove.

The casing and the liquid suction part are fitted with a seal member interposed therebetween to connect the liquid communication path.

The casing and the liquid suction part are injection molded bodies of a resin composition.

In the internal gear pump of the present invention, at least the portions where the casing and the cover are joined to each other are made of an injection molded body of a resin composition, the casing and the cover are fixed, and the casing and the cover are fixed. The two parts are in contact with each other without any gap, and the recess closed portion between the casing and the cover has a gap between the two members, and the gap is sealed with an elastically deformable elastic member provided on the outer periphery of the recess. Therefore, the elastically deformable elastic member is sandwiched between both the casing and the cover and seals between the members, and the deformation absorbs the gap between the two members, and thereby the gap between the fixed portions. The gap between the two members at the fixed portion is eliminated by absorbing the minute amount. As described above, in the present invention, the elastic member that can be elastically deformed has a sealing property and a gap canceling effect at a fixing portion (for example, a bolt fixing portion). As a result, the stress at the time of fastening the casing and the cover can be relieved, and no damage occurs at the time of fastening, and the internal gear pump has a stable discharge performance.

Since the elastic member that can be elastically deformed is a rubber ring, the rubber ring sandwiched between both the casing and cover members absorbs the gap between the two members due to the elastic deformation and seals the casing and the cover well. You can stop.

Each of the casing and the cover has a flange portion on the outer peripheral portion, and the cover is fitted with the casing at a step portion on the inner peripheral side of the flange portion to form a recess closed portion, and the flange portion and the flange portion of the casing Since the fixed portion constitutes the fixed portion, the joint surfaces of the concave portion closed portion and the fixed portion are surfaces at different height positions, and even when there is a variation in dimensional accuracy, elastic deformation at the concave portion closed portion is possible. Due to the elastic deformation of the elastic member, the gap between the joint surfaces at the fixed portion can be easily eliminated. Moreover, it is easy to assemble the cover and the casing by fitting at the step portion.

In the structure where the cover receives the thrust load of the drive shaft fixed to the inner rotor, the stress applied to the cover can be relaxed by the elastically deformable elastic member in the recess closing portion, and the resin cover can be prevented from being damaged in the structure.

Since the inner side surface of the concave portion of the casing is made of a resin body and the bottom surface of the concave portion is made of a metal body, variation in discharge performance can be suppressed on the bottom surface while improving the friction and wear characteristics on the inner side surface.

Since the resin composition forming the cover and the casing is a resin composition comprising a PPS resin as a base resin and blended with at least one selected from glass fiber, carbon fiber, and inorganic filler, dimensional accuracy And the above effects are more easily obtained. 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.

The internal gear pump unit of the present invention includes the internal gear pump of the present invention and a liquid suction nozzle, and the unit includes a trochoid and a casing in which a recess for accommodating the trochoid is formed. And a liquid suction part having a liquid suction nozzle, and the casing and the liquid suction part are detachably fixed by a fixing means while being connected to a liquid communication path provided in each of the casing and the liquid suction part. Without changing the structure of the pump body, the liquid suction part can be partially changed in accordance with the specifications of an actual machine such as a compressor, and the shape can be easily optimized for the specification change. Moreover, since the pump body itself is not changed, the performance change before and after replacement of the liquid suction part can be suppressed. Furthermore, by changing the inner diameter and outer diameter of the liquid suction part (such as its nozzle) as required, it is possible to cope with changes in the suction pressure without changing the configuration of the pump main body part.

Since the fixing means is constituted by a retaining ring fitted into a groove formed across the fitting portion between the casing and the liquid suction portion, both members can be detachably and firmly fixed.

A concave portion for fitting is provided in the casing, and a convex portion for fitting is provided in the liquid suction portion corresponding to the concave portion, and the concave portion for fitting and the convex portion for fitting are combined to form a circumference as a groove. Since the groove is formed, the retaining ring is fitted in the circumferential groove, so that both the casing and the liquid suction part can be attached and detached, and are prevented from rotating with respect to each other in the circumferential direction. To be fixed.

The casing and the liquid suction part are fitted with a seal member interposed and the liquid communication path is connected, so that high sealing performance can be maintained for a long period of time, and reliability is further improved.

In addition, since the casing and the liquid suction part are injection molded bodies of the resin composition, the cost of the entire pump can be reduced.

It is an axial sectional view showing an example of the internal gear pump of the present invention. It is an enlarged view of the junction part of the casing and cover in FIG. It is sectional drawing which shows an example of the elastic member which can be elastically deformed. It is sectional drawing which shows the other example of the elastic member which can be elastically deformed. It is sectional drawing which shows the other example of the elastic member which can be elastically deformed. It is sectional drawing which shows the other example of the elastic member which can be elastically deformed. It is sectional drawing which shows the other example of the elastic member which can be elastically deformed. It is an axial sectional view of an internal gear pump (ideal shape). It is an axial sectional view of an internal gear pump (assumed shape). It is an axial sectional view showing another example of the internal gear pump of the present invention. It is an axial sectional view showing an example of the internal gear pump unit of the present invention. It is a perspective view which shows the state which isolate | separated the pump main-body part and the liquid suction part. It is a perspective view which shows the usage example of the internal gear pump unit of this invention. It is an axial sectional view showing another example of the internal gear pump unit. It is an axial sectional view showing another example of the internal gear pump unit. It is an axial sectional view showing another example of the internal gear pump unit. It is an axial sectional view showing another example of the internal gear pump unit. It is an axial sectional view showing another example of the internal gear pump unit. It is an axial sectional view of a conventional internal gear pump.

An embodiment of the internal gear pump of the present invention will be described with reference to FIGS. FIG. 1 is an axial sectional view of an internal gear pump, and FIG. 2 is an enlarged view of a joint portion between a casing and a cover in FIG. As shown in FIGS. 1 and 2, 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) that rotatably accommodates the trochoid 4. And a cover 6 that closes the trochoid-receiving recess 7 of the casing 5. The casing 5 has a flange portion 5b on the outer peripheral portion, and the cover 6 has a flange portion 6b on the outer peripheral portion. The recessed portion closing portion 12 in the internal gear pump 1 is a step portion 6a in which the cover 6 is a recessed portion on the inner peripheral side of the flange portion 6b, and is fitted to the protruding portion 5a of the casing 5 having a shape corresponding to the step portion 6a. Has been configured. The bolt fixing portion 13 in the internal gear pump 1 is configured such that the cover 6 is bolted to the flange portion 5b of the casing 5 with the flange portion 6b. The internal gear pump 1 has a drive shaft 14 that is coaxially fixed to the center of rotation of the inner rotor 3. The means for the fixing portion is not limited to a bolt, and any means that can fix both members may be used, and examples thereof include a screw and a pin.

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. On the bottom surface 7a of the trochoid accommodating recess 7 of the casing 5, a suction port communicating with the suction-side volume chamber, a discharge port communicating with the discharge-side volume chamber, and a liquid channel 15 are formed. The liquid is pumped from the discharge port through the discharge passage in the center of the drive shaft 14 to the upper compression portion (not shown) in the figure.

In the internal gear pump 1, the trochoid 4 is rotated by the drive shaft 14, whereby 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.

As the material of the outer rotor 2 and the inner rotor 3, a sintered metal (iron-based, copper-iron-based, copper-based, stainless-based, etc.) is preferably used, and iron-based is particularly preferable from the viewpoint of price. A trochoid pump that pumps water, chemicals, or the like may be a stainless steel that has a high rust prevention capability.

The casing 5 and the cover 6 are fixed by a fastening member such as a bolt 9 passed through a bolt hole 8 penetrating both members. As a form of the internal gear pump 1, as a pump unit in which only the casing 5 and the cover 6 are fixed by the bolt 9, while the casing 5 and the cover 6 are integrated with the bolt 9 and fastened to the fixing plate of the apparatus main body. Also good.

In the present invention, in the internal gear pump 1, in addition to the casing 5, the cover 6 is made of resin (injection molded body). The casing 5 and the cover 6 may be formed of an injection-molded body of a resin composition, at least the portions that are joined to each other. In the form shown in FIG. 1, the cover 6 is entirely made of resin, and the casing 5 is mainly made of resin. The casing 5 is in sliding contact with the outer rotor 2 and the inner rotor 3 at the bottom surface 7a and the inner side surface 7b that constitute the trochoid accommodating recess 7. Since the inner side surface 7b of the trochoid accommodating recess 7 is made of a resin body, it is excellent in friction and wear characteristics with the outer rotor 2. The casing 5 is composed of a disk-shaped metal plate 11 in which the bottom surface 7a of the trochoid-containing recess 7 is embedded and integrated in the resin body by composite molding. Thereby, compared with the case where the bottom face 7a is formed with resin, it is excellent in flatness and can suppress the dispersion | variation in discharge performance. As the metal plate 11, a sintered metal body or a molten metal body (sheet metal press product) can be adopted.

The casing 5 is provided with a liquid suction part 5c. The liquid suction part 5 c can be formed integrally when the casing 5 is molded. If necessary, a filter (not shown) can be fixed to the end of the liquid suction part 5c by welding or the like. The filter can prevent foreign matter from entering the pump.

The problem when the casing 5 and the cover 6 are made of resin will be described with reference to FIGS. FIG. 8 is an axial sectional view of an internal gear pump having an ideal shape, and FIG. 9 is an axial sectional view of an internal gear pump having an actually assumed shape. As shown in FIG. 8, when bolting the casing 5 and the cover 6, it is desirable that both the recess closing portion 12 and the bolt fixing portion 13 are in contact with each other without a gap. In this case, damage at the time of fastening the bolt and deterioration of the discharge performance do not occur. However, since the casing 5 and the cover 6 are injection-molded products, it is actually difficult to make both the recess closing portion 12 and the bolt fixing portion 13 without a gap. As shown in FIG. 9, if the assumed shape is set so as to eliminate the gap between the bolt fixing portions 13, a gap is formed in the recess closing portion 12 (FIG. 9A). If this gap is large, the trochoid housing recess, which is the rotor housing portion, cannot be sealed, thus adversely affecting the discharge performance. On the other hand, if it sets so that the clearance gap of the recessed part obstruction | occlusion part 12 may be eliminated, a clearance gap will be made in the bolt fixing | fixed part 13 (FIG.9 (b)). If there is this gap, a stress is generated during bolt tightening, and the casing and the cover may be damaged.

On the other hand, in the present invention, as shown in FIG. 2, in the bolt fixing portion 13 between the casing 5 and the cover 6, the flange portion 6 b of the cover 6 and the flange portion 5 b of the casing 5 are in contact with each other without a gap. In the recess closing portion 12, there is a gap between the casing 5 and the cover 6, and this gap is sealed with an elastically deformable elastic member (rubber ring 10) provided on the outer periphery of the trochoid accommodating recess 7. More specifically, the gap of the recess closing portion 12 is a gap between the step bottom surface 6c of the step portion 6a and the upper end surface of the convex portion 5a of the casing. The rubber ring 10 is sandwiched between both members of the casing 5 and the cover 6 and seals between these members to seal the trochoid accommodating recess 7 and absorbs a gap between the two members by deformation thereof, thereby a bolt fixing portion. The gap of 13 is absorbed and the gap of both members (flange part 5b, 6b) in the bolt fixing | fixed part 13 is eliminated. Thereby, the stress at the time of bolting the casing 5 and the cover 6 can be relieved, the flange portion or the like is not damaged at the time of fastening, and stable discharge performance can be exhibited.

When the casing and the cover have a flat shape as in the prior art, the respective joint surfaces of the recessed portion closing portion and the bolt fixing portion are surfaces at the same height position, and even when the rubber ring is interposed, the recessed portion is closed. It is impossible to eliminate the gap between the bolt fixing portions while eliminating the gap between the portions. In the present invention, for example, as shown in FIG. 2, the recessed portion closing portion 12 in the internal gear pump 1 is configured such that the cover 6 is fitted to the protruding portion 5a of the casing 5 at the step portion 6a, and the bolt fixing portion 13 is provided. The cover 6 is configured to be bolted to the flange portion 5b of the casing 5 by the flange portion 6b. Thereby, since each joint surface in the recessed part obstruction | occlusion part 12 and the bolt fixing | fixed part 13 turns into a surface of a different height position, the rubber ring 10 arrange | positioned in the outer periphery of the trochoid accommodation recessed part 7 at the upper end part of this convex part 5a The above-described configuration can be achieved by utilizing the deformation of the above.

In the embodiment shown in FIG. 1, the cover 6 is structured to receive a thrust load of the drive shaft 14 fixed to the inner rotor 3. In this case, the stress applied to the cover 6 by the rubber ring 10 in the recess closing portion 12 can be relieved, and damage to the resin cover 6 can be prevented.

The rubber ring 10 is an O-ring having a circular cross section. More specifically, as shown in FIG. 3, the rubber ring 10 is an O-ring having a substantially circular cross section in a natural state where no external force is applied. Further, when the O-ring crushing margin is about 1/15 to 1/3, preferably about 2/25 to 1/5 of the cross-sectional diameter of the O-ring, good sealing performance can be expected. For example, when the cross-sectional diameter of the O-ring is 2.0 to 5.0 mm, the crushing allowance of the O-ring is set to about 0.1 to 1.7 mm, preferably about 0.3 to 1.0 mm. If the crushing cost is too small, reliability such as sealing properties cannot be expected, and conversely if too large, there is a concern about compression set of the O-ring. The elasticity of the rubber ring is based on the A type conforming to ISO (International Organization for Standardization) and durometer (Shore). For example, the durometer A hardness of JIS K-6253 is A60 to A100, preferably A70 to A90. If so, a suitable elastic force can be obtained, which is preferable.

The size and the cross-sectional shape are not particularly limited as long as the gap can be adjusted. For example, as shown in FIG. 4, a rubber ring 10a having an X-shaped cross section may be used. Further, as shown in FIG. 5, a rubber ring 10b having a substantially U-shaped cross section may be used. Further, as shown in FIG. 6, a rubber ring 10c having a substantially V-shaped cross section may be used. Further, as shown in FIG. 7, a rubber ring 10d having a substantially rectangular cross section may be used.

Also, the material of the rubber ring 10 is not particularly limited, and a rubber material that matches the application and use environment such as nitrile rubber such as hydrogenated nitrile rubber, fluorine rubber, acrylic rubber, and ethylene propylene 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).

3 to 7 show a rubber ring as an elastic member that can be elastically deformed. However, any elastic member that can absorb a gap between both the casing and the cover by deformation and seal between the two members can be used. It is not limited. For example, a metal mechanical seal may be used as the elastic member that can be elastically deformed.

The resin composition that forms the casing 5 and the cover 6 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 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. With this configuration, the oil resistance and chemical resistance are excellent, and the toughness is excellent. The anisotropy of the injection molding shrinkage reduces the warpage of the flange portion and greatly improves the dimensional accuracy, thereby facilitating the control of the gap.

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 and a cover are respectively molded by injection molding using the pellets for molding. When forming the casing, if necessary, the above-described metal plate or the like is disposed in the mold and integrated by composite molding.

FIG. 10 shows another example of the internal gear pump of the present invention. As shown in FIG. 10, the internal gear pump 21 includes a trochoid 24 in which an inner rotor 23 is accommodated in an annular outer rotor 22, and a circular recess (trochoid accommodating recess) 27 that rotatably accommodates the trochoid 24. And a cover 26 that closes the trochoid-accommodating recess 27 of the casing 25. The casing 25 has a flange portion 25b on the outer peripheral portion, and the cover 26 has a flange portion 26b on the outer peripheral portion. The recessed portion closing portion 32 in the internal gear pump 21 is configured such that the cover 26 is a step portion 26a that is a recessed portion on the inner peripheral side of the flange portion 26b and is fitted to the protruding portion 25a of the casing 25. Further, in the bolt fixing portion 33 between the casing 25 and the cover 26, the flange portion 26b of the cover 26 and the flange portion 25b of the casing 25 are in contact with each other without a gap, and in the recessed portion closing portion 32, the casing 25 and the cover 26 are in contact with each other. There is a gap, and this gap is sealed with an elastically deformable elastic member (rubber ring 30) provided on the outer periphery of the trochoid-containing recess 27.

Here, the internal gear pump 1 shown in FIG. 1 has an internal gear shown in FIG. 10, whereas the shape on the fixed plate side, which is the upper side of the cover 6, corresponds to the step portion 6a. In the pump 21, the fixed plate side of the concave cover 26 is formed flat. In this case, the upper end surface of the internal gear pump 21 on the side to which the drive shaft 34 is connected is a flat surface. Thereby, the internal gear pump can be easily fastened and fixed to the fixing plate of the apparatus main body.

As mentioned above, although demonstrated based on each figure, the internal gear pump of this invention is not limited to these. For example, in the combination of a cover and a casing, in FIG. 1, the cover side is a concave portion and the casing side is a convex portion, but this concave-convex relationship may be reversed.

By the way, in the structure of the conventional internal gear pump, as shown in FIG. 19, it is a unit in which the pump part and the liquid suction part are integrated, and the liquid suction nozzle has a fixed shape. In some cases, the nozzle may not reach the oil level in the liquid (oil) reservoir depending on the model. In that case, it is necessary to replace the entire pump unit with a nozzle whose length has been changed. The replacement of the entire pump unit may cause a difference in performance. Also, when changing the suction pressure or the like, it is necessary to replace the entire pump unit.

In view of such circumstances, the internal gear pump unit of the present invention can change the liquid suction part partially according to the specifications of the actual machine such as a compressor without changing the structure of the pump body. Can be easily applied, and can cope with changes in suction pressure specifications.

An embodiment of the internal gear pump unit of the present invention will be described with reference to FIG. FIG. 11 is an axial sectional view of the internal gear pump unit. For example, in the internal gear pump 1 shown in FIG. 1, the liquid suction portion 5c is integrally formed when the casing 5 is formed, and the casing 5 includes the liquid suction portion 5c, whereas the internal suction pump 5 shown in FIG. In the contact gear pump unit, a casing and a liquid suction part are formed as separate members, and these are fixed detachably by a fixing means.

Specifically, the internal gear pump unit 41 includes a pump main body 52 and a liquid suction part 53. The pump body 52 includes a trochoid 44 in which an inner rotor 43 is accommodated in an annular outer rotor 42, a casing 45 in which a circular recess (trochoid accommodating recess) 47 in which the trochoid 44 is rotatably accommodated, and a casing 45. And a cover 46 for closing the trochoid receiving recess 47. The liquid suction part 53 has a liquid suction nozzle 53a. The liquid suction nozzle 53a is provided along the drive axis direction of the trochoid. Specifically, the liquid suction nozzle 53 a extends on the opposite side of the drive shaft 54 along the axial direction of the drive shaft 54 that is coaxially fixed to the rotation center of the inner rotor 43. The tip of the liquid suction nozzle 53a (the opposite side of the pump main body 52) is immersed in a liquid reservoir to form a part of a communication path to the suction-side volume chamber of the liquid trochoid 44. In the internal gear pump unit 41 of the present invention, the casing 45 of the pump main body 52 and the liquid suction part 53 are detachably fixed by a fixing means while the liquid communication paths provided in the respective parts are connected. It is characterized by being. The basic structure of the pump body 52 is the same as that of the internal gear pump 1 of FIG. 1 except that the casing 45 does not include a liquid suction part.

The material of the casing 45 and the cover 46 is not particularly limited, but is preferably made of resin and an injection-molded body. By setting it as a resin molding, it becomes low-cost compared with the case where it is made from a sintered metal. In the form shown in FIG. 11, the cover 46 is entirely made of resin, and the casing 45 is mainly made of resin. The casing 45 is in sliding contact with the outer rotor 42 and the inner rotor 43 at the bottom surface 47 a and the inner side surface 47 b that constitute the trochoid accommodating recess 47. Since the inner side surface 47b of the trochoid accommodating recess 47 is made of a resin body, it is excellent in friction and wear characteristics with the outer rotor 42. The casing 45 is constituted by a disk-shaped metal plate 51 in which the bottom surface 47a of the trochoid-accommodating recess 47 is embedded and integrated in a resin body by composite molding (insert molding) by injection molding. Thereby, compared with the case where the bottom face 47a is formed with resin, it is excellent in flatness and can suppress the dispersion | variation in discharge performance. As the metal plate 51, a sintered metal body or a molten metal body (sheet metal press product) can be adopted.

In the pump main body 52, the casing 45 has a flange portion 45b on the outer peripheral portion, and the cover 46 has a flange portion 46b on the outer peripheral portion. The closed portion of the trochoid-accommodating concave portion 47 is configured such that the cover 46 is a stepped portion 46a serving as a concave portion on the inner peripheral side of the flange portion 46b and is fitted to the convex portion 45a of the casing 45 having a shape corresponding to the stepped portion 46a. Has been. Moreover, the fixing part of the casing 45 and the cover 46 is comprised by the cover 46 being bolted with the flange part 45b of the casing 45 by the flange part 46b. Such fitting at the stepped portion facilitates the assembly of the cover 46 and the casing 45 and facilitates the manufacture of the pump body.

Further, in the bolt fixing portion of the casing 45 and the cover 46, the flange portion 46b of the cover 46 and the flange portion 45b of the casing 45 are in contact with each other without a gap, and in the closed portion of the trochoid accommodating recess 47, the casing 45 and the cover 46 are in contact. And the gap is sealed with a rubber ring 50 provided on the outer periphery of the trochoid accommodating recess 47. The rubber ring 50 is sandwiched between both members of the casing 45 and the cover 46 and seals between these members to seal the trochoid accommodating recess 47 and absorbs a gap between the two members due to the deformation thereof. The gap between the bolt fixing portions is absorbed to eliminate the gap between the two members (flange portions 45b and 46b) at the bolt fixing portion. Thereby, the stress at the time of bolting the casing 45 and the cover 46 can be relieved, the flange portion or the like is not damaged at the time of fastening, and stable discharge performance can be exhibited. In addition, as the rubber ring 50, the thing similar to the rubber ring 10 of FIG. 1 can be used.

The liquid suction part 53 will be described with reference to FIGS. FIG. 12 is a perspective view showing a state in which the pump body and the liquid suction part are separated. As shown in FIG. 11, the liquid suction nozzle 53 a of the liquid suction portion 53 is a substantially cylindrical nozzle formed along the axial direction of the drive shaft 54 that is coaxially fixed to the rotation center of the inner rotor 43. If necessary, the filter can be fixed to the end of the liquid suction nozzle 53a by welding or the like. The filter can prevent foreign matter from entering the pump. The casing 45 of the pump body 52 and the liquid suction part 53 are detachably fixed by a fixing means. The liquid suction part 53 has a cylindrical one end fitted to an opening end 45 c on the casing 45 opposite to the cover. The inner diameter of the open end 45 c is substantially the same as the outer diameter of the one end of the cylinder of the liquid suction part 53. Further, the end face of the one end of the cylinder and the bottom (the lower surface of the metal plate 51) in the opening end 45c of the casing 45 may be in contact with each other or may be provided with a slight gap. In consideration of adverse effects due to elastic deformation of the casing and the liquid suction portion, it is preferable to provide a gap in the portion.

As shown in FIG. 11, the casing 45 and the liquid suction portion 53 are fitted as described above with the rubber ring 57 serving as a seal member interposed therebetween, and the liquid communication path is connected. The rubber ring 57 is housed in a groove formed on the outer periphery at one end of the cylinder of the liquid suction portion. By interposing a rubber ring, high sealing performance can be maintained over a long period of time, and reliability is further improved. As the rubber ring 57, the rubber ring 57 equivalent to the rubber ring 50 in the pump main body described above can be used. Specifically, the size and cross-sectional shape of the rubber ring 57 are not particularly limited as long as the gap between the casing 45 and the liquid suction portion 53 can be adjusted. As the cross-sectional shape of the rubber ring 57, for example, those shown in FIGS. The rubber ring 50 is elastically deformed mainly in the axial direction of the internal gear pump unit 41 (vertical direction in FIG. 11), whereas the rubber ring 57 is in the radial direction of the internal gear pump unit 41 (see FIG. 11). 11), when the cross-sectional shape shown in FIGS. 5 to 7 is adopted as the rubber ring 57, the cross-section is oriented so as to be easily elastically deformed in the radial direction. It is preferable to change the direction of the shape.

The rubber ring 57 is not particularly limited as long as it is an elastic member that can be elastically deformed and can seal the casing and the liquid suction portion by deformation. For example, a metal mechanical seal may be used as the elastic member that can be elastically deformed.

The fixing means using a retaining ring will be described with reference to FIG. As shown in FIG. 12, the liquid suction portion 53 includes a convex portion 53b (a convex portion for fitting) and a groove 53c formed in the convex portion. The casing 45 of the pump main body 52 has a recess 45e (a recess for fitting) that fits into the protrusion 53b, and a groove 45d that is formed so as to cover the recess. When the convex portion 53b of the liquid suction portion 53 and the concave portion 45e of the casing 45 are fitted, a continuous circumferential groove is formed by the groove 53c and the groove 45d. A retaining ring 56 having a substantially rectangular cross section is inserted into the circumferential groove by opening an abutment and elastically deforming, so that the retaining ring 56 is fitted across the liquid suction portion 53 and the casing 45, and both members are axially moved. It is fixed so as not to come out. In FIG. 12, the convex part 53b of the liquid suction | inhalation part 53 is made into the H shape by which the side view was almost laid down, for example, and a pair of groove | channels 53c are not penetrating each other but are dead ends. An abutment of the retaining ring 56 is aligned with the convex portion 53b having a pair of grooves 53c that are in a dead end shape. Further, by fitting the convex portion 53b and the concave portion 45e, the liquid suction portion 53 and the casing 45 are also prevented from rotating in the circumferential direction. The retaining ring is not particularly limited as long as it can be attached to and detached from the groove and can stably maintain the fixing force over a long period of time. Rubber (no contact) may be used.

Although the material of the liquid suction part 53 is not particularly limited, it is preferably made of resin and an injection-molded body. By using a resin injection molded body, the liquid suction nozzle, the convex portion, the groove, and the like can be integrally molded. As the resin composition for forming the liquid suction part, a resin composition using a synthetic resin capable of injection molding as a base resin is preferable. As this base resin, it is the same as that which forms the above-mentioned casing and cover. Moreover, glass fiber, carbon fiber, or an inorganic filler can be blended with the resin composition alone or in combination as appropriate. By using the liquid suction part, casing, and cover as an injection-molded body of the resin composition, the cost of the entire pump can be reduced.

The liquid suction part, casing, and cover are preferably formed of a resin composition having substantially the same linear expansion coefficient. Most preferably, the same material is used. Thereby, it is difficult to form a gap or the like at each fitting portion due to the difference in linear expansion coefficient, and it is possible to suppress an adverse effect on discharge performance and the like.

An example of use of the internal gear pump unit of the present invention will be described with reference to FIG. In the internal gear pump unit of the present invention, as described above, the casing of the pump main body 52 and the liquid suction portion 53 are detachably fixed by the fixing means while the liquid communication paths provided in the respective pumps are connected. Therefore, only the liquid suction part 53 can be changed without changing the structure of the pump body part 52. In the internal gear pump unit 41 ′ shown in the left diagram of FIG. 13, since the oil level 58 is close, the liquid suction nozzle 53 d has a short liquid suction portion 53. On the other hand, in the internal gear pump unit 41 ″ shown in the right diagram of FIG. 13, since the oil level 58 is distant, the liquid suction nozzle 53 e has a long liquid suction portion 53. In any case, the configuration of the pump body 52 is the same. In this way, the liquid suction part 53 can be partially changed in accordance with the specifications of the actual machine such as a compressor without changing the structure of the pump body 52, and the shape can be easily optimized for the specification change. Further, since the pump main body 52 itself is not changed, a change in pump performance before and after replacement of the liquid suction portion 53 can be suppressed.

Further, in the liquid suction portion 53, the configuration of the trochoid specification of the pump main body portion 52 is adjusted by adjusting the shape of the liquid suction nozzle (for example, changing the length, the inner diameter, and the outer diameter to be a tapered shape). The suction pressure and the discharge amount can be adjusted without changing. As a result, it is possible to cope with various compressors and the like while suppressing manufacturing costs and development costs.

Hereinafter, other examples of the internal gear pump unit of the present invention will be described with reference to FIGS.

In the internal gear pump unit 61 shown in FIG. 14, the liquid suction part 73 including the liquid suction nozzle 73a is formed with a pair of dead ends 73c similar to the fitting convex part shown in FIG. The projection 73b is provided, and the projection 73f is provided on the substantially opposite side of the projection 73b in the circumferential direction. The convex portion 73f is composed of a pair of parallel convex pieces formed along the circumferential direction, and a groove 73g is formed between the pair of convex pieces. That is, the groove 73g is a through groove in which a pair of dead ends (see FIG. 12) are penetrated. The casing 65 is provided with a pair of concave portions 65e and 65e corresponding to the convex portion 73b and the convex portion 73f, respectively.

When the convex portions 73 b and 73 f of the liquid suction portion 73 and the pair of concave portions 65 e and 65 e of the casing 65 are fitted, a continuous circumferential groove is formed by the groove 73 c, the groove 73 g, and the groove on the casing 65. . The retaining ring 76 is fitted into the circumferential groove straddling the liquid suction part 73 and the casing 65 by opening the mouth and elastically deforming and inserting the retaining ring 76. At that time, the stop of the retaining ring 76 is aligned with the convex portion 73b having a pair of grooves 73c having a dead end shape. By doing so, the casing 65 and the liquid suction portion 73 are firmly fixed so as not to be removed in the axial direction while being prevented from rotating in the circumferential direction.

In the parts indicated by other reference numerals, the internal gear pump unit 61 shown in FIG. 14 and the internal gear pump unit 41 shown in FIG. 11 have the same configuration, and therefore detailed description thereof is omitted here. .

As in the internal gear pump unit 81 shown in FIG. 15, a thinned liquid suction nozzle 93a and a liquid suction portion 93 having a convex portion 93b may be used. In this case, it is possible to use the casing 85 whose opening end portion 85c is shortened, and further, a retaining ring 96 having a substantially rectangular cross section with a reduced cross-sectional area and a small-diameter rubber ring 97 with a reduced cross-sectional area. It can also be used.

15, the internal gear pump unit 81 shown in FIG. 15 and the internal gear pump unit 61 shown in FIG. 14 have the same configuration, and therefore detailed description thereof is omitted here. .

In the internal gear pump unit 101 shown in FIG. 16, the upper side of the liquid suction nozzle 113 a of the liquid suction portion 113 is extended toward the metal plate 111. Specifically, the end surface of one end of the cylinder of the liquid suction nozzle 113a extends to reach the position of the lower surface of the metal plate 111. In this case, in order to maintain a gap between the liquid suction nozzle 113a and the metal plate 111, a step is formed at both ends of the lower surface of the metal plate 111 corresponding to the liquid suction nozzle 113a extending upward. Is provided.

In this way, it is possible to increase the contact distance between the casing 105 and the liquid suction portion 113 from the upper side of the liquid suction nozzle 113a to the rubber ring 117, and in the fitting portion between the casing 105 and the liquid suction portion 113. It becomes possible to make it easier to prevent liquid leakage.

In the parts indicated by other reference numerals, the internal gear pump unit 101 shown in FIG. 16 and the internal gear pump unit 41 shown in FIG. 11 have the same configuration, so detailed description thereof will be omitted here. .

Also in the internal gear pump unit 121 shown in FIG. 17, the liquid suction part 133 in which the upper side of the liquid suction nozzle 133 a is extended toward the metal plate 131 is used. Also in this case, a step is provided on the lower side of the metal plate 131 in response to the liquid suction nozzle 133a extending upward.

By doing so, it becomes possible to increase the contact distance between the casing 125 and the liquid suction portion 133 from the upper side of the liquid suction nozzle 133a to the rubber ring 137, and in the fitting portion between the casing 125 and the liquid suction portion 133. It is possible to make it easier to prevent liquid leakage.

In the parts indicated by other reference numerals, the internal gear pump unit 121 shown in FIG. 17 and the internal gear pump unit 61 shown in FIG. 14 have the same configuration, and therefore detailed description thereof is omitted here. .

Also in the internal gear pump unit 141 shown in FIG. 18, the liquid suction part 153 in which the upper side of the liquid suction nozzle 153a extends toward the metal plate 151 is used. Also in this case, a step is provided on the lower side of the metal plate 151 in response to the liquid suction nozzle 153a extending upward.

By doing so, it is possible to increase the contact distance between the casing 145 and the liquid suction portion 153 from the upper side of the liquid suction nozzle 153a to the rubber ring 157, and in the fitting portion between the casing 145 and the liquid suction portion 153. It is possible to make it easier to prevent liquid leakage.

In the parts indicated by other reference numerals, the internal gear pump unit 141 shown in FIG. 18 and the internal gear pump unit 81 shown in FIG. 15 have the same configuration, so detailed description thereof will be omitted here. .

As mentioned above, although demonstrated based on each figure, the internal gear pump unit of this invention is not limited to these. For example, in FIG. 11, the pump body 52 is fixed to the flange 45 b of the casing 45 by the flange 46 b while the cover 46 is fitted to the casing 45 by the step 46 a on the inner peripheral side of the flange 46 b. The casing 45 of the pump main body 52 and the liquid suction part 53 are detachably fixed by a fixing means while the liquid communication paths provided in the pump main body part 52 are connected to each other. For example, as shown in the configuration of FIG. 19, the casing and the cover that are flat with each other may be fixed to form the pump body.

The internal gear pump of the present invention is low in cost because the cover and casing are made of resin, but does not break when these two members are fastened, and has stable discharge performance, so oil, water, chemicals, etc. It can be used as an internal gear pump (trochoid pump) that pumps liquid. In particular, it can be suitably used as a pump for supplying a liquid to a sliding part of a scroll compressor for an electric water heater, room air conditioner, or car air conditioner that uses alternative chlorofluorocarbon or carbon dioxide as a refrigerant. Further, the internal gear pump unit of the present invention can partially change the liquid suction portion without changing the structure of the pump body, and can also cope with the change in the specification of the suction pressure, so that oil, water, It can be applied to various models as an internal gear pump unit (trochoid pump) that pumps a liquid such as a chemical solution.

1,21 Internal gear pump 2,22 Outer rotor 3,23 Inner rotor 4,24 Trochoid 5,25 Casing 5a, 25a Protruding part 5b, 25b Flange part (casing)
5c, 25c Liquid suction part 6, 26 Cover 6a, 26a Step part 6b, 26b Flange part (cover)
7, 27 Trochoid accommodating recess 7a, 27a Bottom surface 7b, 27b Inner side surface 8, 28 Bolt hole 9, 29 Bolt 10, 30 Rubber ring (elastic member capable of elastic deformation)
11, 31 Metal plate 12, 32 Recess closing part 13, 33 Bolt fixing part 14, 34 Drive shaft 15, 35 Liquid flow path 41, 41 ', 41'', 61, 81, 101, 121, 141 Internal gear pump Unit 42, 62, 82, 102, 122, 142 Outer rotor 43, 63, 83, 103, 123, 143 Inner rotor 44, 64, 84, 104, 124, 144 Trochoid 45, 65, 85, 105, 125, 145 Casing 45a , 65a, 85a, 105a, 125a, 145a Convex part 45b, 65b, 85b, 105b, 125b, 145b Flange (casing side)
45c, 65c, 85c, 105c, 125c, 145c Open end 45d, 105d Groove 45e, 65e, 105e, 125e Recess 46, 66, 86, 106, 126, 146 Cover 46a, 66a, 86a, 106a, 126a, 146a Step 46b, 66b, 86b, 106b, 126b, 146b Flange (cover side)
47, 67, 87, 107, 127, 147 Trochoid-receiving recess 47a, 67a, 87a, 107a, 127a, 147a Bottom surface 47b, 67b, 87b, 107b, 127b, 147b Inner surface 48, 68, 88, 108, 128, 148 Bolt hole 49, 69, 89, 109, 129, 149 Bolt 50, 70, 90, 110, 130, 150 Rubber ring 51, 71, 91, 111, 131, 151 Metal plate 52, 72, 92, 112, 132, 152 Pump body 53, 73, 93, 113, 133, 153 Liquid suction part 53a, 73a, 93a, 113a, 133a, 153a Liquid suction nozzle 53b, 73b, 93b, 113b, 133b, 153b Projection part 53c, 73c, 113c 133c groove 53d Liquid suction nozzle 53e Liquid suction nozzle 54, 74, 94, 114, 134, 154 Drive shaft 55, 75, 95, 115, 135, 155 Liquid flow path 56, 76, 96, 116, 136, 156 Retaining ring 57, 77 , 97, 117, 137, 157 Rubber ring 58 Oil surface 73f, 133f Convex part 73g, 133g Groove

Claims (12)

1. 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 and the cover are each made of an injection-molded body of a resin composition, at least a portion to be joined to each other ,
   The casing and the cover are fixed, and the fixing portion between the casing and the cover is in contact with both members without a gap, and the recess closing portion between the casing and the cover is a gap between both members. An internal gear pump characterized in that the gap is sealed with an elastically deformable elastic member provided on the outer periphery of the recess.
2. 2. The internal gear pump according to claim 1, wherein the elastically deformable elastic member is a rubber ring.
3. Each of the casing and the cover has a flange portion at an outer peripheral portion, and the cover is fitted with the casing at a step portion on the inner peripheral side of the flange portion to form the recessed portion closing portion. The internal gear pump according to claim 1, wherein the fixed portion is configured to be fixed to a flange portion of the casing.
4. The internal gear pump according to claim 1, wherein the casing and the cover are fixed by bolts.
5. The internal gear pump according to claim 1, wherein the cover is configured to receive a thrust load of a drive shaft fixed to the inner rotor.
6. 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.
7. 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.
8. 2. An internal gear pump comprising: the internal gear pump according to claim 1; and a liquid suction nozzle having a tip immersed in the liquid reservoir and forming a part of a communication path to the suction-side volume chamber. A unit,
   The internal gear pump unit includes a pump body having the trochoid and the casing, and a liquid suction part having the liquid suction nozzle.
   The casing of the pump body and the liquid suction part are detachably fixed by a fixing means while being connected to the liquid communication path provided in each of them. Gear pump unit.
9. 9. The internal gear pump according to claim 8, wherein the fixing means includes a retaining ring that is fitted into a groove formed across the casing and the liquid suction portion. unit.
10. A fitting recess is provided in the casing, and the fitting portion is provided in the liquid suction portion corresponding to the recess, and the fitting recess and the fitting projection are combined, The internal gear pump unit according to claim 9, wherein a circumferential groove is formed as the groove.
11. 9. The internal gear pump unit according to claim 8, wherein the casing and the liquid suction part are fitted with a seal member interposed therebetween to connect the liquid communication path.
12. The internal gear pump unit according to claim 8, wherein the casing and the liquid suction part are injection molded bodies of a resin composition.

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