JP2013189924A - Method for manufacturing internal gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely prevent the exfoliation of a cover by achieving the sufficient fixing strength of swaging-fixing parts in a region on the side of a discharge-side volumetric chamber receiving high internal pressure, when the cover is fixed to a casing by swaging.SOLUTION: When a cover 20 of an internal gear pump 1 is fixed to a casing 10 by swaging, the cover 20 is housed in a cover housing recess 13 and a press die, in which a plurality of pressing parts are annularly arranged corresponding to the outer peripheral edge of the cover 20, is used to provide a plurality of swaging-fixing parts 71 in a spotted manner by pressing a wall part of the peripheral wall of the cover housing recess 13 by the pressing parts. On that occasion, the distance of the swaging-fixing parts 71 from a boundary line L, dividing an intake-side volumetric chamber R1 and a discharge-side volumetric chamber R2, in a region on the side of the discharge-side volumetric chamber R2 is adjusted so that the fixed force by all of the swaging-fixing parts 71 becomes 2,900 N or more.

Description

  The present invention relates to a method for manufacturing an internal gear pump suitable for pumping fluid such as lubricating oil.

  As this type of pump, a trochoid pump having a suction port and a discharge port, in which an outer rotor and an inner rotor having a trochoidal tooth shape are rotatably accommodated in a casing and communicated with the casing, is known. A plurality of internal teeth are formed on the inner peripheral portion of the outer rotor, and an outer tooth having one fewer teeth than the inner teeth of the outer rotor is formed on the outer peripheral portion of the inner rotor. The inner rotor is inscribed in the outer rotor, and both rotors A plurality of closed spaces are formed between them.

  A drive shaft is fixed to the inner rotor, and when the drive shaft is driven to rotate, the inner rotor rotates, and the outer rotor rotates in the same direction while the outer teeth of the inner rotor mesh with the inner teeth of the outer rotor. At this time, in the casing, among the plurality of closed spaces formed between the outer rotor and the inner rotor, the space whose volume increases is the suction side volume chamber, and the space whose volume decreases is the discharge side volume chamber. . A suction port is connected to the suction-side volume chamber, and a discharge port is connected to the discharge-side volume chamber. As each rotor rotates, fluid such as hydraulic fluid is sucked from the suction port into the suction-side volume chamber, Next, the volume chamber on the suction side is changed to the volume chamber on the discharge side, and the fluid is discharged from the discharge port (see Patent Document 1, etc.).

JP 2006-329054 A

  A cover that closes the housing recess of the outer rotor and the inner rotor is fixed to the casing. As a means for fixing the cover to the casing, caulking that is plastically deformed so that the outer peripheral edge of the cover covers the casing-side meat is used. Such a caulking fixing portion may be provided in a spot manner at regular intervals rather than over the entire outer peripheral edge of the cover, in which case the claw-shaped caulking piece on the casing side is attached to the outside of the cover. The peripheral edge is covered and crimped. By the way, in a pump in operation, the discharge-side volume chamber in the casing is always in a high pressure state, so that the area on the discharge-side volume chamber side of the cover that is caulked and fixed to the casing has a high internal pressure. receive. As a result, there is a possibility that the cover is peeled from the casing due to insufficient strength of the caulking fixing portion, that is, the caulking piece.

  The present invention has been made in view of the above circumstances, and its main technical problem is that when the cover is caulked and fixed to the casing, the fixing strength of the caulking fixing portion in the region on the discharge side volume chamber side that receives a high internal pressure is sufficient. It is another object of the present invention to provide a method for manufacturing an internal gear pump that can reliably prevent peeling of a cover.

  The manufacturing method of the internal gear pump of the present invention includes a rotor housing recess, a casing having a cover housing recess around the opening of the rotor housing recess, an outer rotor having internal teeth rotatably accommodated in the rotor housing recess, An inner rotor that is rotatably accommodated in the outer rotor and has outer teeth that are inscribed in the inner teeth, a drive shaft that is coaxially fixed to the axis of the inner rotor, the drive shaft penetrates, and the cover A disc-shaped cover that is disposed in the housing portion and closes the rotor housing recess, and whose outer peripheral edge is caulked and fixed to the casing, the rotor housing recess being closed by the cover, An internal gear position in which a suction side volume chamber into which fluid is sucked and a discharge side volume chamber into which the sucked fluid is discharged is formed by the meshing action of the teeth and the external teeth. When the cover is caulked and fixed to the casing, a plurality of caulking fixing portions are provided spot-on to the casing of the cover, and the fixing force by all the caulking fixing portions in the region on the discharge side volume chamber side is 2900 N or more. It is characterized by setting to.

  According to the present invention, the fixing strength by all the caulking fixing portions in the area on the discharge side volume chamber side of the cover that receives a high internal pressure is set to 2900 N or more, so that the fixing strength is sufficient and the cover is surely peeled off. Can be suppressed.

  In the present invention, as an example of obtaining the fixing force, the total distance from the boundary line that separates the suction-side volume chamber and the discharge-side volume chamber of the caulking fixing portion in the region on the discharge-side volume chamber side, A concrete means is to set the distance satisfying the fixing force.

  In the present invention, a pressing die in which a plurality of pressing portions are annularly arranged at equal intervals corresponding to the outer peripheral edge portion of the cover is rotated relative to the casing to cause the phase of the pressing portion. And the caulking fixing portion is formed by the pressing portion.

  According to the present invention, when the cover is caulked and fixed to the casing, it is possible to reliably suppress peeling of the cover by ensuring that the fixing strength of the caulking fixing portion in the region on the discharge side volume chamber side that receives a high internal pressure is sufficient. A method for manufacturing a gear pump is provided.

It is (a): top view of the internal gear pump which concerns on one Embodiment of this invention, (b): It is BB sectional drawing of (a). It is a top view which shows the outer rotor and inner rotor of the pump. It is a top view which shows the process of crimping and fixing a cover to a casing in the pump. It is sectional drawing which shows the same process. It is sectional drawing which shows the condition of the caulking fixation by one Embodiment in detail. It is a top view of the pump which shows the distance from the boundary line which divides a suction side volume chamber and a discharge side volume chamber to the caulking fixed part by the side of a discharge side volume chamber, and (a) one embodiment and (b) in a comparative example is there.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIGS. 1A and 1B are a plan view and a cross-sectional view showing a trochoid internal gear pump (hereinafter referred to as a pump) 1 according to the present embodiment, respectively. The pump 1 includes a disk-shaped casing 10 and a cover 20, and further includes an outer rotor 30 and an inner rotor 40 accommodated in the casing 10, and a drive shaft 50 fixed to the inner rotor 40. FIG. 2 is a plan view of the outer rotor 30 and the inner rotor 40.

  As shown in FIG. 1B, the casing 10 has a cylindrical convex portion 11 protruding from the back surface (lower surface in FIG. 1), and a circular shape on the surface side opposite to the convex portion 11. The rotor accommodating recess 12 is formed. Around the opening of the rotor housing recess 12, an annular cover housing recess 13 and a caulking step 19 are formed in a step shape toward the surface. The convex portion 11, the rotor accommodating concave portion 12, the cover accommodating concave portion 13 and the caulking step portion 19 are formed concentrically with the center of the casing 10.

  O1 shown in FIG. 1B is the center of the casing 10, and the convex portion 11, the rotor accommodating concave portion 12, the cover accommodating concave portion 13 and the caulking step portion 19 are formed concentrically with the central O1 of the casing 10. . As shown in FIG. 1A, a suction port 14 and a discharge port 15 that communicate with the rotor housing recess 12 from the back side are formed at the bottom of the rotor housing recess 12. A cover 20 is fitted into the cover receiving recess 13 and fixed by caulking, and the rotor receiving recess 12 is closed by the cover 20. A plurality (three in this case) of mounting holes 16 are formed around the rotor housing recess 12 of the casing 10. These attachment holes 16 are holes through which bolts for attaching the pump 1 to a predetermined device are passed.

  As shown in FIG. 1A, a positioning groove 17 extending in the axial direction is formed at a predetermined location on the outer peripheral surface of the casing 10. A semicircular cutout 18 is formed at a predetermined location on the peripheral wall 12 a of the rotor accommodating recess 12. The casing 10 is manufactured by a method such as molding an aluminum alloy by a die casting method, for example.

  An annular outer rotor 30 is housed in the rotor housing recess 12 so as to be slidable and rotatable, and the inner rotor 40 is rotatably housed in the outer rotor 30 while being inscribed therein. As shown in FIG. 2, a plurality of inner teeth 31 are formed on the inner peripheral surface of the outer rotor 30, and outer teeth 41 that mesh with the inner teeth 31 of the outer rotor 30 are formed on the outer peripheral surface of the inner rotor 40. The number of outer teeth 41 of the inner rotor 40 is one less than the inner teeth 31 of the outer rotor 30, and the center O2 of the inner rotor 40 is eccentric with respect to the center O1 of the outer rotor 30 as shown in FIGS. Yes.

  As shown in FIG. 2, the inner teeth 31 and the outer teeth 41 of the rotors 30 and 40 are in contact with each other at a partition point P, and are surrounded between the partition points P and between the cover 20 and the bottom of the rotor accommodating recess 12. The space to be formed becomes the suction-side or discharge-side volume chamber R. A drive shaft fitting hole 42 is formed at the center of the inner rotor 40 to which a tip drive portion 51 formed in a substantially D-shaped cross section of the drive shaft 50 is fitted and fixed. An annular boss 43 is formed around the drive shaft fitting hole 42 in a protruding manner. The outer rotor 30 and the inner rotor 40 are manufactured by a manufacturing method such as sintering by a powder metallurgy method, for example.

  As shown in FIG. 1A, the cover 20 is formed with a circular drive shaft through-hole 21 through which the drive shaft 50 passes through the boss 43 of the inner rotor 40. The drive shaft through hole 21 is eccentric with respect to the center of the cover 20. A protrusion 22 that fits into the notch 18 of the casing 10 is formed at a predetermined position on the outer peripheral edge of the cover 20. The cover 20 is manufactured by punching a sheet metal, for example.

  The cover 20 is fitted into the cover receiving recess 13 by fitting the protrusion 22 into the notch 18 and fitting the drive shaft through hole 21 to the boss 43 of the inner rotor 40. As shown in FIG. 5A, the depth of the cover receiving recess 13 is deeper than the thickness of the cover 20, that is, the height of the peripheral wall 13 a of the cover receiving recess 13 in the state where the cover 20 is received in the cover receiving recess 13. The height is higher than the surface height of the cover 20.

  As shown in FIG. 1, the inner rotor 40 in the rotor housing recess 12 is concentric with the drive shaft through hole 21 of the cover 20 fitted in the cover housing recess 13 (O2 in FIG. 1A is the center). The drive shaft 50 is fitted and fixed in the drive shaft fitting hole 42 of the inner rotor 40 concentric with the cover 20. That is, the axis of the drive shaft coincides with O2 and is eccentric with respect to the rotation center of the outer rotor 30 (the same as the center O1 of the casing), and the drive shaft 50 is attached to the cover 20 via the boss 43 of the inner rotor 40. It will be in the state supported rotatably. The suction port 14 and the discharge port 15 formed in the casing 10 are formed at symmetrical positions with a line L connecting the rotation center O1 of the outer rotor 30 and the axis O2 of the drive shaft 50 as a symmetry line.

  In the pump 1 of the present embodiment, the drive shaft 50 is rotationally driven by a drive source such as a motor, and the inner rotor 40 is rotated. When the inner rotor 40 rotates, the outer rotor 30 rotates in the same direction while the outer teeth 41 mesh with the inner teeth 31. The arrow shown on the inner rotor 40 in FIG. 2 is the rotation direction. When the inner rotor 40 rotates in this direction, the volume chamber R formed between the partition points P is the same as the suction side volume chamber R1 on the suction port 14 side. And the discharge side volume chamber R2 on the discharge port 15 side.

  In the pump 1, as the rotors 30 and 40 rotate, fluid such as hydraulic oil is sucked into the suction side volume chamber R1 from the suction port 14, and then the suction side volume chamber R1 is changed to the discharge side volume chamber R2. The pump action in which the fluid is discharged from the discharge port 15 is continuously performed.

  Now, in the pump 1 of the present embodiment having the above-described configuration, the outer rotor 30 is accommodated in the rotor accommodating recess 12, the inner rotor 40 is accommodated in the outer rotor 30, the cover 20 is fitted in the cover accommodating recess 13, and the cover 20 is attached to the casing 10. After that, the drive shaft 50 is fitted into the drive shaft fitting hole 42 of the inner rotor 40 and fixed to be assembled.

  A method of caulking and fixing the cover 20 to the casing 10 is according to the present invention, and examples thereof will be shown below. As shown in FIG. 3A, the protrusion 22 is fitted into the notch 18, the drive shaft through hole 21 is fitted into the boss 43 of the inner rotor 40, and the cover 20 is fitted into the cover housing recess 13.

  Next, the cover 20 is fixed by spot-caulking the peripheral wall 13 a of the cover accommodating recess 13 of the casing 10 with respect to the outer peripheral edge of the cover 20 by a pressing die 60 shown in FIG. 4. The pressing die 60 has a plurality of (in this case, eight) claw-shaped pressing portions 61 arranged on the lower surface in an annular shape at equal intervals, and can be moved up and down above the receiving die 65 and has a vertical axis. It is arrange | positioned so that rotation is possible centering on.

  The receiving die 65 has a positioning hole 65a into which the convex portion 11 on the back side of the casing 10 is fitted, and the convex portion 11 is fitted into the positioning hole 65a from above so that the casing 10 is placed as shown in FIG. Set in receiving mold 65. Next, as shown in FIG. 4 (b), the pressing die 60 is lowered, the pressing portion 61 is applied to the inner peripheral side of the caulking step portion 19, and the peripheral wall 13 a of the cover housing recess 13 of the casing 10 is pressed. A plurality of caulking fixing portions 71 are provided on the outer peripheral edge (see FIGS. 5A to 5B).

  The pressing portion 61 is a position corresponding to the outer peripheral edge portion of the cover 20, and is disposed at a position straddling the outer peripheral edge portion of the cover 20 and the peripheral wall 13 a of the cover receiving recess 13 as shown in FIG. Yes. When the pressing portion 61 is lowered, the meat portion of the peripheral wall 13a of the cover receiving recess 13 is crushed from above by the pressing portion 61 as shown in FIG. The outer peripheral edge portion of 20 is covered and pressed. As a result, the outer peripheral edge portion of the cover 20 is caulked and fixed to the casing 10, and as shown in FIG. 3B, caulking fixing portions 71 are provided at eight spots according to the number of pressing portions 61.

  In the present embodiment, the eight caulking fixing portions 71 are arranged on the symmetry line (hereinafter referred to as a boundary line) L that separates the suction side volume chamber R1 and the discharge side volume chamber R2 in the casing 10 as shown in FIG. Provided at positions that are evenly distributed on both sides. In order to provide the caulking fixing portion 71 as described above, when the caulking die 60 is caulked, the pressing die 60 is rotated so that the pressing portions 61 are evenly arranged separately on both sides of the boundary line L. Then, the pressing die 60 is lowered and the caulking fixing portions 71 are provided by the pressing portions 61. Thereafter, the pressing die 60 is retracted upward, and the pump 1 is removed from the receiving die 65.

  The pump 1 is manufactured in this way. In this pump 1, the region on the discharge side volume chamber R2 side of the cover 20 with respect to the casing 10 in the discharge side volume chamber R2 side (below the boundary line L in FIG. 1). The fixing force of the caulking fixing portion 71 of the cover 20 is set to 2900N or more. In addition, since all the caulking fixing portions 71 have the same structure and the same number, the fixing force of the region on the suction side volume chamber R1 side (the upper side of the boundary line L in FIG. 1) is set to 2900 N or more. become.

  Such a fixing force (F) of the cover 20 is based on a force that resists a load that peels the cover 20 due to an internal pressure when the pump 1 is operated and the inside of the discharge-side volume chamber R2 becomes a high pressure state. That is, the load Fp that peels off the cover 20 generated in the discharge-side volume chamber R2 is an internal pressure P × area (area of the region on the discharge-side volume chamber R2 side of the cover 20) A, and is a specific force that exceeds this Fp. The value is set to 2900N or more.

  Examples of the conditions for setting the cover fixing force F to 2900 N or more include the number, shape, thickness, and the like of the caulking fixing portions 71. These conditions include the casing 10 and the cover whose dimensions are fixed by the pressing die 60. Since the caulking fixing portions 71 provided for 20 are substantially the same, the cover fixing force F differs depending on the position of the caulking fixing portion 71.

  That is, in the pressing die 60 in which the caulking fixing portions 71 are evenly provided at the eight locations, the position of the caulking fixing portion 71 can be changed by rotating and displacing the phase of the pressing portion 61. In the present embodiment, as shown in FIG. 6A, caulking fixing portions 71 are provided in a state of being divided into four portions in each of the suction side volume chamber R1 side and the discharge side volume chamber R2 side on both sides of the boundary line L. ing. In contrast, FIG. 6B shows a comparative example in which the formation position of the caulking fixing portion 71 is changed by the same pressing die 60. In this comparative example, caulking fixing portions 71 are arranged at two intersections between the boundary line L and the outer peripheral edge of the cover 20, and the caulking fixing portions are provided in the respective areas on the suction side volume chamber R1 side and the discharge side volume chamber R2 side. 71 is provided in three places, and the phase of the pressing portion 61 is shifted by 22.5 ° with respect to the embodiment.

  Here, although eight caulking fixing portions 71 are formed by the same pressing die 60, the fixing force of the cover 20 is different depending on the position of the caulking fixing portion 71 in this embodiment and the comparative example. That is, the total distance La from the boundary line L to the caulking fixing portion 71 on the discharge-side volume chamber R2 side is La = (La1 × 2) + (La2) as shown in FIG. In contrast, in the comparative example, Lb = (Lb1 × 1) + (La2 × 2), and La> Lb from the actual distance.

  The area on the discharge side volume chamber R2 side of the cover 20 is subjected to a load in the direction of separating from the cover receiving recess 13 due to the internal pressure of the discharge side volume chamber R2, but the load is negative in the suction side volume chamber R1. In combination with this, the discharge-side volume chamber R2 side of the cover 20 is rotated about the boundary line L as a fulcrum (rotating shaft) to be separated. Therefore, the distance from the boundary line L to the caulking fixing portion 71 is related to the moment. Therefore, the longer the distance, the larger the moment force and the stronger the fixing force for pressing the cover 20. Therefore, when the total distance from the boundary line L to the caulking fixing portion 71 is compared, the position of the caulking fixing portion 71 of this embodiment is effective because the present embodiment is longer than the comparative example. In the comparative example, the fixing force F of the cover 20 is less than 2900N, and the cover 20 may be peeled off.

DESCRIPTION OF SYMBOLS 1 ... Internal gear pump 10 ... Casing 12 ... Rotor accommodation recessed part 13 ... Cover accommodation recessed part 20 ... Cover 30 ... Outer rotor 31 ... Inner tooth 40 ... Inner rotor 41 ... Outer tooth 50 ... Drive shaft 60 ... Pushing die 61 ... Pressing part 71 ... Caulking fixing part L ... Boundary line

Claims (3)

A casing having a rotor housing recess and a cover housing recess around the opening of the rotor housing recess;
An outer rotor having internal teeth rotatably accommodated in the rotor accommodating recess;
An inner rotor rotatably accommodated in the outer rotor and having outer teeth inscribed in the inner teeth;
A drive shaft that is coaxially fixed to the inner rotor axis;
A disk-shaped cover through which the drive shaft passes and which is disposed in the cover housing portion to close the rotor housing recess and whose outer peripheral edge portion is caulked and fixed to the casing;
With
A suction-side volume chamber into which fluid is sucked and a discharge-side volume chamber into which the sucked fluid is discharged are formed in the rotor housing recess closed by the cover by the meshing action of the inner teeth and the outer teeth. In the internal gear pump
In the caulking and fixing of the cover to the casing, a plurality of caulking fixing portions for the casing of the cover are provided in spots, and the fixing force by all the caulking fixing portions in the region on the discharge side volume chamber side is set to 2900 N or more. A method of manufacturing an internal gear pump, characterized in that   The total distance from the boundary line that separates the suction side volume chamber and the discharge side volume chamber of the caulking fixing portion in the region on the discharge side volume chamber side is set to a distance that satisfies the fixing force. A manufacturing method of the internal gear pump according to claim 1.   After adjusting the phase of the pressing portion by rotating a pressing die in which a plurality of pressing portions are annularly arranged at equal intervals corresponding to the outer peripheral edge portion of the cover, The method for manufacturing an internal gear pump according to claim 1, wherein the caulking fixing portion is formed by the pressing portion.

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