JP2020045765A - Internal gear pump - Google Patents

Abstract

To provide an internal gear pump which can position a trochoid by a simple structure, and can prevent the positional displacement and an inclination of the trochoid.SOLUTION: An internal gear pump 1 has a trochoid 4 in which an inner rotor 3 is rotatably accommodated in an outer rotor 2, and a suction-side volume chamber and a discharge-side volume chamber are formed, a casing 5 in which an accommodation part 8 for accommodating the trochoid 4 is formed, and a cover 6 for blocking the accommodation part 8 of the casing 5. An inside face 8b of the accommodation part 8 of the casing 5 is formed of an injection molded body having a resin composition, a bottom face 8a of the accommodation part 8 is formed of a metal plate 7 which is integrally arranged therewith at injection molding, the inner rotor 3 has a salient part 3a salient to one end face in an axial direction, the metal plate 7 has a recess 7 into which the salient part 3a is fit, and the salient part 3a of the inner rotor 3 is fit into the recess 7a of the metal plate 7.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an internal gear pump (trochoid pump) for pumping a liquid such as oil, water, or a chemical solution, and particularly to an internal gear pump used in an industrial machine field, for example, an air conditioning compressor.

  BACKGROUND ART Conventionally, as an internal gear pump (trochoid pump), Patent Document 1 and the like are known. The structure of the internal gear pump will be described with reference to FIG. FIG. 6 is a sectional view of a conventional internal gear pump. As shown in FIG. 6, the pump 21 mainly includes 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 housed in a circular trochoid housing portion 28 formed in a cylindrical casing 25 with a flange. A cover 26 for closing the trochoid housing 28 is fixed to the casing 25. A drive shaft 33 that is rotated by a drive source (not shown) penetrates and is fixed to the axis of the inner rotor 23.

  The casing 25 is an injection molded body manufactured by injection molding using a resin composition. The casing 25 and the cover 26 are fastened and fixed to a fixing plate 32 of the device body by bolts 30 passed through respective bolt holes 29. Further, a rubber ring (O-ring) 31 is attached to a groove formed on the outer periphery of the concave portion of the casing 25 on a joint surface (joint surface) between the casing 25 and the cover 26. The rubber ring 31 is used to seal the trochoid storage portion 28, and prevents liquid from leaking from the mating surface of the casing 25 and the cover 26.

  In such a structure, the suction-side and discharge-side volume chambers are formed between the partition points where the rotors come into contact with each other, according to the rotation direction of the trochoid 24. When the drive shaft 33 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, and the rotation increases the volume, 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 whose volume decreases due to rotation of the trochoid 24 and the internal pressure increases, from which the sucked liquid is discharged to the discharge port.

  In Patent Literature 1, the casing 25 is made of an injection molded body (resin molded body), so that the casing 25 is inexpensive and has a higher degree of freedom in shape as compared with a case where the entire casing is made of metal parts. Further, since the inner surface of the trochoid housing portion 28 is formed of a resin molded body, the slidability with the outer rotor 22 is excellent. On the other hand, the bottom surface of the trochoid storage portion 28 is formed of a disk-shaped metal plate 27 integrated with the casing 25 by composite molding in order to suppress variations in the discharge performance. In the metal plate 27, a liquid path such as a suction port and a discharge port is formed, and the disk surface other than the path is a smooth surface.

JP 2014-51964 A

  In the internal gear pump of Patent Literature 1, the trochoid is not positioned, and when the trochoid is mounted on the metal plate, the trochoid is mounted eccentrically from the originally assumed position or inclined with respect to the upper surface of the metal plate. May be attached. In particular, in the pump of FIG. 6, since the inner surface of the trochoid housing portion 28 is formed of a resin molded body, when the trochoid is mounted eccentrically, the outer peripheral surface of the outer rotor 22 does not fit on the inner surface of the trochoid housing portion 28. Sliding contact is even, and there is a concern that the inner surface may be worn. Further, when the trochoid is attached at an angle, an abnormal load may be applied to the rotating trochoid.

  As a trochoid positioning structure, for example, a structure is known in which the diameter of a hole in a cover through which a rotating shaft is inserted is increased, and a convex portion of an inner rotor protruding toward the cover is passed through the hole. However, a simpler structure is required in assembling the pump.

  The present invention has been made in view of such circumstances, and in an internal gear pump in which an inner surface of a trochoid housing portion is formed of a resin molded body and a bottom surface of the housing portion is formed of a metal plate, a trochoid with a simple structure is provided. It is an object of the present invention to provide an internal gear pump capable of positioning the trochoid and preventing the trochoid from shifting or tilting.

The internal gear pump of the present invention is such that an inner rotor having a plurality of external teeth is rotatably housed in an outer rotor having a plurality of internal teeth in a state in which the external teeth mesh with the internal teeth and are eccentric. A trochoid, in which a suction-side volume chamber for sucking a liquid and a discharge-side volume chamber for discharging the liquid sucked into the suction-side volume chamber are formed between the inner teeth and the outer teeth, and contains the trochoid. An internal gear pump having a casing in which a housing portion to be formed is formed, and a cover for closing the housing portion of the casing, wherein an inner surface of the housing portion of the casing is formed by injection molding of a resin composition. The bottom surface of the housing portion is formed of a metal plate integrally provided at the time of injection molding. The inner rotor has a protruding protrusion on one end surface in the axial direction, and the metal plate is fitted with the protrusion. Is Has a recess,
The projection of the inner rotor is fitted in the depression of the metal plate.

  The convex portion is a cylindrical body having a circular outer shape protruded coaxially with the shaft hole of the inner rotor, and at least a part of the outer peripheral surface of the cylindrical body is fitted to the inner peripheral surface of the concave portion. It is characterized by.

  The metal plate has a through hole for introducing the liquid into the accommodation space for the trochoid, and a concave groove that is a flow path of the liquid, and the concave portion does not communicate with the through hole. And a concave shape communicating with the concave groove.

  A groove depth from an end surface of the metal plate to a bottom surface of the concave groove is larger than a depth of a concave portion from an end surface of the metal plate to a bottom surface of the concave groove.

  The outer rotor and the inner rotor are sintered metal bodies.

  An internal gear pump according to the present invention includes a trochoid, a casing in which a housing portion for housing the trochoid is formed, and a cover for closing the housing portion of the casing. Since the bottom surface of the housing portion is formed of a metal plate, it is possible to improve the slidability with the outer rotor and suppress variations in the discharge performance. Further, the inner rotor has a protruding projection on one end face in the axial direction, and the metal plate has a recess in which the projection is fitted. Since the projection is fitted in the recess, Trochoid positioning is possible, and trochoid displacement can be prevented. As a result, the discharge amount does not decrease due to the eccentricity. Further, since the inner rotor does not tilt more than the clearance between the convex portion and the concave portion, it is possible to prevent an abnormal load from being applied to the rotating trochoid.

  In the above pump, the protrusion of the inner rotor and the recess of the metal plate are assembled inside when the pump is assembled. The pump can be easily assembled simply by stacking it from above.

  In the present invention, in particular, the inner surface of the housing portion is a resin molded body, and there is a concern that the inner surface may be worn due to a trochoid misalignment. , Excessive wear can be prevented.

It is an exploded perspective view showing an example of an internal gear pump of the present invention. It is a top view showing the internal gear pump of the present invention. FIG. 3 is a sectional view taken along line AA of the internal gear pump of FIG. 2. It is a plan view of an inner rotor. It is an enlarged view of the metal plate integrally formed with the casing. It is an axial sectional view of the conventional internal gear pump.

  One embodiment of the internal gear pump of the present invention will be described with reference to FIGS. 1 is an assembled perspective view of the internal gear pump, FIG. 2 is a plan view of the internal gear pump, and FIG. 3 is a sectional view taken along line AA of FIG. As shown in FIGS. 1 and 2, an 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 accommodating portion (trochoid accommodating portion) accommodating the trochoid 4 rotatably. ) 8 and a cover 6 for closing the trochoid housing 8 of the casing 5. The cover 6 may have any shape as long as it closes the trochoid housing portion 8, and has, for example, an annular shape. Note that the cover 6 may have a shape that matches the outer shape of the upper surface of the casing 5 in which the trochoid housing portion 8 opens. Three bolt holes 9 are formed in the casing 5. The internal gear pump 1 is fastened and fixed to a plate (not shown) of the device main body by a fixing screw (not shown) passed through each bolt hole 9. Further, the internal gear pump 1 has a drive shaft 10 coaxially fixed to the rotation center of the inner rotor 3 (see FIG. 3).

  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 in contact with and mesh with the inner teeth. A volume chamber on the suction side and the volume on the discharge side are formed between partition points where the rotors come into contact with each other, according to the rotation direction of the trochoid 4. As shown in FIG. 3, a liquid flow path including a discharge port communicating with a discharge-side volume chamber is formed on the bottom surface 8 a of the trochoid storage portion 8 of the casing 5. The liquid is pressure-fed from the discharge port to a compression section (not shown) in the upper part of the figure through a discharge flow path in the center of the drive shaft 10.

  In the internal gear pump 1, the trochoid 4 is rotated by the drive shaft 10, so that the liquid is sucked into the pump from the suction port into the suction-side volume chamber in which the volume increases and the pressure becomes negative. The suction side volume chamber is changed to a discharge side volume chamber whose volume is reduced by rotation of the trochoid 4 and the internal pressure is increased. From this discharge side volume chamber, the sucked liquid is discharged to the discharge port. The above pumping action is continuously performed by the rotation of the trochoid 4, and the liquid is continuously pumped. Further, due to the liquid sealing effect in which the airtightness of each volume chamber is enhanced by the sucked liquid, the differential pressure generated between each volume chamber is increased, and a large pump action is obtained.

  For the outer rotor and the inner rotor, it is preferable to use a sintered metal (iron-based, copper-iron-based, copper-based, stainless steel-based, etc.), and in particular, iron-based from the viewpoint of price. Note that a trochoid pump that pumps water, a chemical solution, or the like may employ a stainless steel or the like having high rust prevention capability.

  The material of the cover 6 is not particularly limited, but is preferably made of resin and preferably made of an injection molded body. When the cover 6 is formed of a resin molded body, the cost is reduced as compared with the case where the cover 6 is formed of a sintered metal or the like.

  In the internal gear pump of the present invention, the casing is an injection-molded body of a resin composition. Thus, the entire shape of the pump can be formed without machining by injection molding, which is economical. On the other hand, if the flatness of the bottom surface of the trochoid storage portion is deteriorated due to resin sink or the like, the ejection performance may vary. This is particularly noticeable when the liquid path including the discharge port and the suction port are formed on the bottom surface of the trochoid storage section. For this reason, in the casing 5, the bottom surface 8 a of the storage section 8 is formed of a disk-shaped metal plate 7. The metal plate 7 is integrated with the casing 5 by composite molding. As described above, while improving the slidability by using the inner surface of the trochoid accommodating portion as the injection molded body portion of the resin composition, the bottom surface of the trochoid accommodating portion is made of an insert-molded metal plate. Variations in ejection performance are suppressed.

  When the trochoid 4 rotates, the bottom surface 8a of the trochoid housing portion 8 is in sliding contact with the outer rotor 2 and the inner rotor 3. In the conventional internal gear pump, these sliding contact surfaces are mutually planar (see FIG. 6). In this case, the trochoid may be displaced or tilted.

  In the internal gear pump of the present invention, the inner rotor 3 has a protruding portion 3a protruding from one end face in the axial direction, and the metal plate 7 has a concave portion 7a. In the pump 1, since the protrusion 3a of the inner rotor 3 and the recess 7a of the metal plate 7 are fitted to each other, the trochoid can be positioned at a position originally expected. Thereby, the relative displacement of the trochoid in the radial direction on the metal plate can be restricted. As a result, it is possible to prevent excessive wear of the inner surface of the housing portion due to the displacement and occurrence of an abnormal load due to the inclination of the trochoid.

  The configuration of the inner rotor will be described with reference to FIG. FIG. 4A is a plan view of the inner rotor, and FIG. 4B is a sectional view of the inner rotor taken along line BB. As shown in FIG. 4, a shaft hole 3 b into which the drive shaft is inserted and fixed is formed in the center of the inner rotor 3. The convex portion 3a is a cylindrical portion that protrudes in the axial direction coaxially with the center of the circle of the shaft hole 3b, and the inner peripheral surface of the cylindrical portion forms a part of the shaft hole 3b. The protrusion height (cylinder length) of the protrusion 3a of the cylindrical portion is, for example, 2 mm. When the convex portion 3a has a cylindrical shape, the outer peripheral shape may be circular as long as the inner peripheral shape is not particularly limited. For example, when the shaft hole 3b is not circular (such as a polygon), the inner peripheral shape of the projection 3a may be a shape that matches the through hole.

  The configuration of the metal plate will be described with reference to FIG. FIG. 5 is an enlarged view of the metal plate 7 integrated with the casing 5. The metal plate 7 has a concave portion 7a in which the above-mentioned convex portion is fitted. Further, the metal plate 7 has a through hole 7b which is a suction port for introducing a liquid into the accommodation space of the trochoid 4, and a concave groove 11 which is a liquid flow path. The through-hole 7b penetrates to the opposite side of the metal plate 7, whereas the concave portion 7a and the concave groove 11 do not penetrate to the opposite side of the metal plate 7. The concave portion 7a is not in communication with the through hole 7b, but has a concave shape in communication with the concave groove 11. That is, the recess 7a is configured so as not to interfere with the suction port communicating with the volume chamber on the suction side.

  As shown in FIG. 5, the concave portion 7a is formed in a substantially crescent shape in a plan view, is a part of the concave groove 11, and is formed at a central portion of the metal plate 7 (a discharge port at a central portion of the drive shaft). (The part connected to the road). The concave portion 7a has a concave shape communicating with the discharge port. The inner peripheral surface of the concave portion 7a has an arc shape in plan view, and has a shape along the cylindrical outer peripheral surface of the above-described convex portion 3a. In this case, the inner diameter of the arc of the concave portion 7a is substantially the same as the outer diameter of the cylinder of the convex portion 3a, or the inner diameter of the arc of the concave portion 7a is slightly larger. The inner peripheral surface of the concave portion 7a preferably has an arc of 180 ° or more in plan view, and more preferably has an arc of 240 ° or more.

  In addition, a portion of the inner peripheral surface of the concave portion 7 a where the arc is missing is a portion of the concave groove 11. Therefore, a part of the cylindrical outer peripheral surface of the convex portion 3a is exposed to the concave groove 11 without being covered by the internal peripheral surface of the concave portion 7a. When the pump is driven, since the inner rotor rotates in such a state, it is preferable that the circumferential ends 7c on both sides of the inner peripheral surface of the concave portion 7a be chamfered.

  As shown in FIG. 5, the depth from the upper surface of the metal plate 7 to the bottom surface of the concave groove 11 (groove depth) is greater than the depth from the upper surface of the metal plate 7 to the bottom surface of the concave portion 7a (recess depth). It is getting bigger. Therefore, the concave portion 7a is a step. The depth of the concave portion 7a is substantially the same as or slightly larger than the height of the protrusion of the convex portion 3a, and is, for example, 2.1 mm. The groove depth of the concave groove 11 is, for example, 2.5 mm.

  As the metal plate 7, a sintered metal body or a smelted metal body (sheet metal pressed product) can be adopted. Examples of the sintered metal material include those similar to the outer rotor and the inner rotor described above. Examples of the molten metal material include iron, aluminum, aluminum alloy, copper, and copper alloy. It is preferable to use a sintered metal body because it has excellent dimensional accuracy and can be firmly integrated with the resin portion by the anchor effect during injection molding.

  The casing 5 is an injection molded body of a resin composition. Examples of the synthetic resin (base resin) that can be injection-molded include thermoplastic polyimide resin, polyether ketone (PEK) resin, polyether ether ketone (PEEK) resin, polyphenylene sulfide (PPS) 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 may be a polymer alloy in which two or more kinds are mixed. Among these resins, it is particularly preferable to use a PPS resin because the molded article is excellent in creep resistance, load resistance, abrasion resistance, chemical resistance and the like.

  Use of glass fiber, carbon fiber, or inorganic filler, which is effective in increasing strength, elasticity, dimensional accuracy, imparting wear resistance, and removing anisotropy of injection molding shrinkage, alone or in combination as appropriate Is preferred. Among them, the combined use of the glass fiber and the inorganic filler is excellent in economy and excellent in friction and wear characteristics in oil.

  The means for mixing and kneading the above-mentioned various raw materials is not particularly limited, and the powder raw materials are dry-mixed with a Henschel mixer, a ball mixer, a ribbon blender, a Redige mixer, an Ultra Henschel mixer, etc., and further twin-screw extruded. The mixture is melt-kneaded by a melt extruder such as an extruder to obtain molding pellets (granules). In addition, when the filler is charged, a side feed may be adopted when melt-kneading with a twin-screw extruder or the like. Using this molding pellet, insert molding is performed with the metal plate held in an injection mold to obtain a casing integrated with the metal plate.

  As described above, the internal gear pump according to the present invention is not limited to these drawings.

  The internal gear pump according to the present invention can prevent the trochoid from being displaced or tilted with a simple structure while enabling weight reduction and cost reduction, etc., so that the internal gear pump for pressure-feeding a liquid such as oil, water, or a chemical solution. It can be used as a pump (trochoid pump). In particular, it can be suitably used as a pump for supplying a liquid to a sliding portion of a scroll type compressor for an electric water heater, a room air conditioner, or a car air conditioner using an alternative chlorofluorocarbon or carbon dioxide as a refrigerant.

DESCRIPTION OF SYMBOLS 1 Internal gear pump 2 Outer rotor 3 Inner rotor 3a Convex part 3b Shaft hole 4 Trochoid 5 Casing 6 Cover 7 Metal plate 7a Concave part 7b Through hole 7c Circumferential end 8 Housing part 8a Bottom surface 8b Inner side surface 9 Bolt hole 10 Drive shaft 11 Concave groove

Claims (5)

An inner rotor having a plurality of external teeth is rotatably accommodated in the outer rotor having a plurality of internal teeth in a state where the external teeth are meshed with the internal teeth, and eccentric. A trochoid between which a suction-side volume chamber for sucking the liquid and a discharge-side volume chamber for discharging the liquid sucked into the suction-side volume chamber; and a casing in which a housing portion for housing the trochoid is formed. An internal gear pump having a cover for closing the housing portion of the casing,
An inner side surface of the housing portion of the casing is formed of an injection molded body of a resin composition, and a bottom surface of the housing portion is formed of a metal plate provided integrally during injection molding,
The inner rotor has a protruding projection on one end surface in the axial direction, and the metal plate has a recess into which the projection is fitted,
An internal gear pump, wherein a convex portion of the inner rotor is fitted into a concave portion of the metal plate.   The convex portion is a cylindrical body having a circular outer peripheral shape protruded coaxially with a shaft hole of the inner rotor, and at least a part of an outer peripheral surface of the cylindrical body is fitted to an inner peripheral surface of the concave portion. 2. The internal gear pump according to claim 1, wherein:   The metal plate has a through hole for introducing the liquid into the accommodation space for the trochoid, and a concave groove that is a flow path of the liquid, and the concave portion does not communicate with the through hole. 3. The internal gear pump according to claim 1, wherein the internal gear pump has a concave shape communicating with the concave groove.   The internal gear pump according to claim 3, wherein a groove depth from an end surface of the metal plate to a bottom surface of the concave groove is larger than a concave depth from an end surface of the metal plate to a bottom surface of the concave groove.   The internal gear pump according to any one of claims 1 to 4, wherein the outer rotor and the inner rotor are sintered metal bodies.

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