JP2014181620A - Gear pump and method of manufacturing inner rotor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear pump for improving its discharge performance by making teeth higher while suppressing an increase in the size and a reduction in the number of teeth, and for achieving adequate clearances between each of external teeth of an inner rotor and each of internal teeth of an outer rotor.SOLUTION: Each of external teeth 20 of an inner rotor 2 includes a tooth top part 21 formed by an epitrochoid curve which is obtained by non-slidably rolling an external rolling circle Co while circumscribing it on a base circle BC and whose trochoid coefficient is larger than a value of 1, a tooth bottom part 22 formed by a hypotrochoid curve which is obtained by non-slidably rolling an internal rolling circle Ci while inscribing it on the base circle BC and whose trochoid coefficient is larger than a value of 1, and an intermediate part 23 formed by an involute curve and located between the tooth top part 21 and the tooth bottom part 22.

Description

  The present invention relates to a gear pump including an inner rotor having a plurality of external teeth, an outer rotor having a plurality of internal teeth and arranged eccentrically with respect to the inner rotor, and an inner rotor constituting the gear pump together with the outer rotor. It relates to the manufacturing method.

  Conventionally, as an inner rotor of this type of gear pump, a meshed portion of a tooth bottom portion formed by a hypocycloid curve and an outer rotor formed by an involute curve, and a curve such as an epicycloid curve, a circular arc curve or a part of an ellipse What is provided with the external tooth | gear which has the formed tooth-tip part is known (for example, refer patent document 1). In addition, as an inner rotor and an outer rotor of this type of gear pump, there are a tooth tip or a tooth root including a profile drawn from a cycloid that can be generated by a rotating action of a pitch circle on a fixed circle, a radial clearance, and the radial direction. There is also known one provided with external teeth or internal teeth having a meshing tooth portion including a tangential clearance smaller than the clearance (see, for example, Patent Document 2). In this inner rotor and outer rotor, the above-mentioned tooth tip and tooth root are, in the case of a tooth tip, the circumference of a pitch circle having a radius that continuously decreases from the two sides of the vertex portion, and in the case of a tooth root, the vertex portion. Are formed by or from the trajectory of a point on the circumference of a pitch circle having a radius that increases or decreases continuously from the two sides. Further, as a technology related to the inner rotor of this type of gear pump, a tooth profile formed by a cycloid curve, an envelope of a group of arcs having a center on a trochoid curve, or an arc curve formed by two arcs in contact with each other, etc. A device that is linearly multiplied in the radial direction or the circumferential direction and deformed into an ellipse is also known (see, for example, Patent Documents 3 and 4).

Japanese Patent No. 4557514 Japanese Patent No. 4243498 Japanese Patent No. 4650180 Japanese Patent No. 4803442

  In the gear pump as described above, the outer rotor and the entire apparatus, and thus the entire device, are reduced in size while the volume of the interdental chamber defined by the outer teeth and the inner teeth is increased to increase the discharge amount. It is required to increase the tooth height of teeth (and internal teeth). However, if the tooth height of a general external tooth or the like having a tooth tip or a root formed by a cycloid curve is increased, the tooth thickness of the external tooth or the like increases at the same time. ) Increases, and it becomes difficult to reduce the size of the inner rotor, outer rotor, and thus the entire apparatus. On the other hand, if the increase in the rotor diameter is to be suppressed, the number of teeth of the inner rotor or outer rotor must be reduced, and if the number of teeth is reduced, the pulsation of discharge pressure is generally reduced by reducing the number of interdental chambers. It gets bigger.

  For this reason, in the gear pump described in Patent Document 1, the eccentric amount of the rotation center of the outer rotor with respect to the rotation center of the inner rotor is increased, thereby suppressing an increase in the outer diameter of the rotor and maintaining the number of teeth. I'm trying to increase the length. However, in the gear pump described in Patent Document 1, particularly when the tooth tip portion is formed by an epicycloid curve, two basic circles are required for the design of the tooth tip portion and the tooth bottom portion. It becomes complicated and it is difficult to obtain an appropriate tooth profile. Further, in the gear pump described in Patent Document 1, the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor is kept relatively small when the inner rotor and the outer rotor rotate as the tooth height increases. There is a possibility that the seal width indicating the range in the thickness direction of the sagging narrows and the volumetric efficiency of the gear pump deteriorates. Further, even if the tooth height of the outer teeth such as the inner rotor is increased using the technique described in Patent Document 2, the outer teeth of the inner rotor and the like increase from the root side to the top of the tooth tip as the tooth height increases. Since the taper is tapered, it is not possible to prevent the seal width from being narrowed. Further, in the inner rotors described in Patent Document 3 and Patent Document 4, the same problem occurs because the outer teeth and the like taper from the root side toward the top of the tooth tip as the tooth height increases. End up.

  Therefore, the present invention can improve the discharge performance by increasing the tooth height while suppressing the increase in size and the reduction in the number of teeth, and can optimize the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor. The main object is to provide a gear pump and a method for manufacturing an inner rotor.

  The gear pump and inner rotor manufacturing method according to the present invention employs the following means in order to achieve the main object.

The gear pump according to the present invention comprises:
In a gear pump comprising an inner rotor having a plurality of external teeth, and an outer rotor having a plurality of internal teeth larger than the outer teeth of the inner rotor and arranged to be eccentric with respect to the inner rotor,
Each of the outer teeth of the inner rotor is obtained by rolling at least on the front side in the rotational direction of the inner rotor without slipping while making an outer circle having a radius smaller than the radius of the drawing point circumscribe the base circle. Hypothesis obtained by rolling a tooth tip formed by an epitrochoid curve and an inversion circle having a radius smaller than the radius of the drawing point without slipping while inscribed in the base circle common to the epitrochoid curve It includes a tooth bottom portion formed by a trochoid curve and an intermediate portion formed by an arbitrary curve and positioned between the tooth tip portion and the tooth bottom portion.

  The inventors of the present invention conducted intensive research to increase the tooth height and improve the discharge performance of the gear pump while suppressing increase in size and reduction in the number of teeth, and the radius of the drawing point is larger than the radius of the abduction circle, An epitrochoidal curve obtained by dividing the radius of the drawing point by the radius of the abduction circle or an epitrochoid curve having a value greater than 1 or the radius of the drawing point is larger than the radius of the inversion circle. We focused on the hypotrochoid curve in which the trochoid coefficient obtained by dividing by the radius of the adductor circle is larger than 1. Such an epitrochoid curve or hypotrochoid curve includes a loop formed when the drawing point moves around the base circle, and is generally considered difficult to adopt as a tooth profile in a gear pump. As a result of considering the characteristics of the portion other than the loop portion of the epitrochoid curve or hypotrochoid curve in which the trochoid coefficient is larger than the value 1, the portions other than the loop portion are the tooth tip portion and tooth of the external tooth. It has been found to be very useful in forming the bottom.

  That is, the distance between the portion other than the loop portion of the epitrochoid curve having a trochoid coefficient larger than 1 and the center of the base circle is longer than that of an epicycloid curve having the same radius of the abduction circle. In addition, the distance between the portion other than the loop portion of the hypotrochoid curve having a trochoid coefficient greater than 1 and the center of the basic circle is shorter than that of a hypocycloid curve having the same radius of the inversion circle. Based on these, the present inventors formed at least the front tooth tip portion in the rotational direction of each external tooth of the inner rotor by a portion other than the loop portion of the epitrochoid curve having a trochoid coefficient larger than value 1, At least the front tooth bottom in the direction of rotation is formed by a portion other than the hypotrochoid curve loop having the epitrochoid curve and the base circle in common and the trochoid coefficient larger than 1, and between the tooth tip and the tooth bottom. The intermediate part was formed by an arbitrary curve.

  As a result, by increasing the drawing point radius while keeping the radius of the abduction circle and adduction circle (the radius of the ∝ basic circle / the number of teeth) small, The tooth height can be easily increased while defining the shape and keeping the basic circle (the outer diameter of the inner rotor) small. According to the studies by the present inventors, the tip portion and the bottom portion of the outer teeth of the inner rotor are caused by an epitrochoid curve or a hypotrochoid curve having a trochoid coefficient larger than 1 as described above. By forming the tooth height and increasing the tooth height, the clearance in the tooth thickness direction where the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor is kept relatively small, that is, the seal width is maintained well. It was confirmed that Therefore, in this gear pump, while suppressing increase in size and reduction in the number of teeth, the tooth height is easily increased to improve discharge performance, and the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor is optimized. It becomes possible.

  Further, the inner rotor sets the radius of the drawing point of the epitrochoid curve and the radius of the abduction circle to “rde” and “re”, respectively, and sets the radius of the drawing point of the hypotrochoid curve and the inversion of the inner rotation. It may be configured to satisfy rde = rdh = Rd and re = rh = R when the radius of the circle is “rdh” and “rh”, respectively.

  The present inventors have further studied to ensure the above-mentioned seal width in the gear pump as described above more appropriately. Then, the present inventors match the radius rde of the drawing point of the epitrochoid curve with the radius rdh of the drawing point of the hypotrochoid curve, and add the radius re of the epicenter of the epitrochoid curve and the adduction of the hypotrochoid curve. It is found that the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor can be kept substantially constant over a wider range, that is, the seal width can be expanded when the radius rh of the circle is matched. It was. Accordingly, if the gear pump is configured to satisfy Rde = Rdh = Rd and re = rh = R, the tooth tip portion formed by the epitrochoid curve and the tooth bottom portion formed by the hypotrochoid curve in the tooth thickness direction. Easily adjust the clearance between the outer teeth of the inner rotor and the inner teeth of the outer rotor by adjusting the size, that is, the rotation angle range of the abduction and inversion circles to create the tooth tip and root can do. Therefore, in this gear pump, the volume efficiency is improved by reducing the clearance between the tooth tips and ensuring the sealing performance, and the generation of cavitation is suppressed by ensuring the clearance between the outer teeth and the inner teeth to some extent. It is possible to easily achieve both.

  Furthermore, the inner rotor may be configured to satisfy Rd ≦ 2.5 · R. That is, when the radius of the epitrochoid curve drawing point and the radius of the hypotrochoid curve drawing point are matched, and the radius of the epitrochoid curve abduction circle and the radius of the hypotrochoid curve adduction circle are matched By setting the radius of the drawing point of the epitrochoid curve and hypotrochoid curve to 2.5 times or less, more preferably 1.5 to 2.0 times the radius of the abduction circle and the inversion circle, It is possible to keep the clearance between the teeth and the inner teeth of the outer rotor substantially constant in a practically sufficiently wide range (seal width).

  The intermediate portion may be formed by an involute curve. This makes it possible to mesh the outer teeth and the inner teeth more smoothly and make the speed ratio between the inner rotor and the outer rotor constant.

  Further, the inner rotor has a diameter of the base circle of the epitrochoid curve and the hypotrochoid curve as “Rbt”, a diameter of the base circle of the involute curve as “Rbi”, and the rotation with respect to the rotation center of the inner rotor. When the eccentric amount of the rotation center of the outer rotor is “e”, it may be configured to satisfy Rbi ≦ Rbt. That is, when the diameter Rbi of the base circle of the involute curve, the diameter Rbt of the base circle of the epitrochoid curve and the hypotrochoid curve, and the eccentricity e satisfy such a relationship, the diameter of the base circle of the involute curve is equal to the inner rotor. Therefore, even if the inner rotor is made smaller by reducing the diameter Rbt of the basic circle of the epitrochoid curve and the hypotrochoid curve within the range satisfying this relationship, the intermediate portion is in an involute curve. Can be formed.

  The gear pump communicates with an interdental chamber that expands with rotation of the inner rotor and the outer rotor among a plurality of interdental chambers defined by the external teeth and the internal teeth. You may further provide a port and two independent discharge ports connected with the interdental chamber shrink | contracted with rotation of the said inner rotor and the said outer rotor among these interdental chambers. That is, according to the present invention, while suppressing the increase in the size of the gear pump and the decrease in the number of teeth of the inner rotor, etc., the tooth height is increased to improve the discharge performance, and the outer teeth of the inner rotor and the inner teeth of the outer rotor Therefore, it is possible to realize a two-port gear pump that is compact and has good discharge performance.

  Further, the tooth profile of the outer rotor defined by the plurality of inner teeth is “e” as the amount of eccentricity of the rotation center of the outer rotor with respect to the rotation center of the inner rotor. When the clearance between the outer tooth tip and the inner tooth tip when the rotational center of the rotor, the tooth tip of the outer tooth and the tooth tip of the inner tooth are aligned is “t” The rotation center of the inner rotor is revolved by a predetermined angle on a circumference of diameter 2 · e + t centered on the rotation center of the outer rotor, and the inner rotor is rotated when the rotation center of the inner rotor revolves by a predetermined angle. Is determined based on an envelope drawn with respect to a plurality of tooth profile lines obtained by rotating by the predetermined angle and a rotation angle corresponding to the number of teeth of the inner rotor. It may be. This makes it possible to easily obtain an outer rotor that can be properly meshed with the inner rotor as described above.

The method for producing an inner rotor according to the present invention includes:
In the method of manufacturing an inner rotor that has a plurality of external teeth and is arranged to be eccentric with respect to the outer rotor having a plurality of internal teeth larger than the external teeth and constitutes a gear pump together with the outer rotor.
The tooth is formed by an epitrochoid curve obtained by rolling an abduction circle having a radius smaller than the radius of the drawing point on the front side of at least the inner rotor in the rotational direction of each of the outer teeth without slipping while circumscribing the base circle. A hypotrochoid curve obtained by rolling an inversion circle having a radius smaller than the drawing point radius while inscribed in the basic circle common to the epitrochoid curve and forming a tip portion without slipping And an intermediate portion located between the tooth tip portion and the tooth bottom portion is formed by an arbitrary curve.

  According to this method, while suppressing the enlargement of the inner rotor and the decrease in the number of teeth, the tooth height is easily increased to improve the discharge performance of the gear pump, and the outer teeth of the inner rotor and the inner teeth of the outer rotor It becomes possible to optimize the clearance.

It is a schematic structure figure showing a gear pump concerning one embodiment of the present invention. It is a schematic block diagram which shows the external tooth of the inner rotor contained in the gear pump shown in FIG. It is a schematic diagram which shows the creation procedure of the internal tooth of the outer rotor contained in the gear pump shown in FIG. It is a graph which shows an example of the relationship between the rotation angle around the rotation center of an inner rotor, and the clearance of an external tooth and an internal tooth. It is a schematic diagram which illustrates the method of measuring the clearance of an external tooth and an internal tooth. It is a schematic block diagram which shows the gear pump which concerns on the deformation | transformation aspect of this invention.

  FIG. 1 is a schematic configuration diagram showing a gear pump 1 according to an embodiment of the present invention. A gear pump 1 shown in the figure is mounted as an oil pump on a vehicle (not shown), and sucks hydraulic oil (ATF) stored in an oil pan and pumps it to a hydraulic control device (both not shown). . The gear pump 1 includes, for example, a pump housing (not shown) configured by a pump body fixed to a transmission case of an automatic transmission and a pump cover fastened to the pump body. An inner rotor (drive gear) 2 and an outer rotor (driven gear) 3 that are rotatably arranged in the gear housing chamber.

  The inner rotor 2 is fixed to a rotating shaft 4 connected to a crankshaft (both not shown) of an engine mounted on a vehicle (not shown), and is rotated by power applied to the rotating shaft 4. A plurality (13 teeth in this embodiment) of external teeth 20 are formed on the outer periphery of the inner rotor 2. On the other hand, the number of internal teeth 30 that is one more than the total number of external teeth 20 of the inner rotor 2 is formed on the inner periphery of the outer rotor 3. The outer rotor 3 is rotatable in the gear housing chamber in a state in which a plurality of inner teeth 30 positioned on the lower side in FIG. 1 mesh with corresponding outer teeth 20 of the inner rotor 2 and are eccentric with respect to the inner rotor 2. Placed in. Further, a plurality of interdental chambers (pump chambers) 5 are formed between the inner rotor 2 and the outer rotor 3 by the plurality of external teeth 20 and the plurality of internal teeth 30.

  As a result, when the inner rotor 2 rotates in the direction of the arrow in FIG. 1 by the power from the rotating shaft 4, the outer rotor 3 has a portion of the plurality of inner teeth 30 meshed with a portion of the plurality of outer teeth 20. Rotate in the same direction together with the inner rotor 2 around a rotation center 3c that is separated from the rotation center 2c of the inner rotor 2 by an eccentric amount e. In the upstream region in the rotation direction of the inner rotor 2 and the outer rotor 3 (mainly the right half region in FIG. 1), the volume of each interdental chamber 5 increases as the inner rotor 2 and the outer rotor 3 rotate ( Swell). Further, in the downstream region in the rotation direction of the inner rotor 2 and the like (mainly the left half region in FIG. 1), the volume of each interdental chamber 5 decreases (contracts) as the inner rotor 2 and the outer rotor 3 rotate. )

  The pump housing (not shown) of the gear pump 1 has an interdental space that expands with the rotation of the inner rotor 2 and the outer rotor 3 among the plurality of interdental chambers 5 defined by the external teeth 20 and the internal teeth 30. A suction port 6 extending in a substantially arc shape so as to communicate (opposite) with the chamber 5, and an interdental chamber 5 that contracts as the inner rotor 2 and the outer rotor 3 of the plurality of interdental chambers 5 rotate. A discharge port 7 extending in a substantially arc shape so as to communicate (oppose) is formed. The suction port 6 and the discharge port 7 may be formed on both sides of the inner rotor 2 and the outer rotor 3 (both the pump body and the pump cover), and one side of the inner rotor 2 and the outer rotor 3 (the pump body and the pump). It may be formed on one of the covers. Further, the suction port 6 may be formed on one side of the inner rotor 2 and the outer rotor 3, and the discharge port 7 may be formed on the other side of the inner rotor 2 and the outer rotor 3.

  FIG. 2 is a schematic configuration diagram showing the external teeth 20 of the inner rotor 2. As shown in the figure, each external tooth 20 of the inner rotor 2 includes a tooth tip portion 21, a tooth bottom portion 22, and an intermediate portion 23 positioned between the tooth tip portion 21 and the tooth bottom portion 22. The tooth tip portion 21 is formed in a convex curved surface by an epitrochoid curve having a trochoidal coefficient larger than 1 obtained by dividing the radius rde of the first drawing point by the radius re of the abduction circle Co. It includes a tooth tip 21t that is located at the center of the tooth 20 in the tooth thickness direction and serves as the top of the convex curved surface. Further, the tooth bottom portion 22 is formed in a concave curved surface by a hypotrochoid curve having a trochoid coefficient larger than a value 1 obtained by dividing the radius rdh of the second drawing point by the radius rh of the inversion circle Ci, It includes a tooth bottom 22b that is located at the center in the tooth thickness direction of the external tooth 20 and is the deepest part of the concave curved surface. In the present embodiment, the external teeth 20 of the inner rotor 2 are formed symmetrically with respect to a line segment connecting the tooth tip 21t of the tooth tip portion 21 (and the tooth bottom 22b of the tooth bottom portion 22) and the rotation center 2c.

  As shown in FIG. 2, the epitrochoid curve forming the tooth tip portion 21 maintains the radius rde of the first drawing point at the first value Rde (constant value) and has a radius smaller than the first value Rde. The outer rotation circle Co having re is obtained by rolling the outer rotation circle Co without slipping while circumscribing the base circle BCt having the rotation center 2c and the center O of the inner rotor 2 in common. Further, the hypotrochoid curve forming the tooth bottom portion 22 is the same as the epitrochoid curve forming the tooth tip portion 21 and the basic circle BCt, and as shown in FIG. 2, the radius rdh of the second drawing point. Is maintained at the second value Rdh (a constant value), and the inversion circle Ci having a radius rh smaller than the second value Rdh is rolled without slipping while inscribed in the basic circle BCt.

  Here, the epitrochoid curve or hypotrochoid curve having a trochoid coefficient larger than 1 includes a loop portion formed when the drawing point moves in the vicinity of the basic circle BCt, as shown by a two-dot chain line in FIG. . Therefore, it is considered that such epitrochoid curves and hypotrochoid curves are generally difficult to adopt as a tooth profile in a gear pump, but the present inventors have developed a tooth height while suppressing an increase in size and a decrease in the number of teeth. As a result of earnest research to improve the discharge performance of the gear pump by increasing the height of the gear teeth, the portion other than the epitrochoid curve and the hypotrochoid curve having a trochoid coefficient larger than 1 is the tip portion 21 of the external tooth 20 It has been found that it is extremely useful for forming the root 22.

  That is, the distance between the portion other than the loop portion of the epitrochoid curve having a trochoidal coefficient larger than 1 and the center O of the basic circle BCt is longer than that of the epicycloid curve having the same radius of the abduction circle. . Further, the distance between the portion other than the loop portion of the hypotrochoid curve having a trochoid coefficient greater than 1 and the center O of the base circle BCt is shorter than that of the hypocycloid curve having the same radius of the inversion circle. . Based on these, the present inventors formed the tip portion 21 of each external tooth 20 of the inner rotor 2 by a portion other than the loop portion of the epitrochoid curve in which the trochoid coefficient is greater than 1, and the root portion 22. Is formed by a portion other than the loop of the hypotrochoid curve in which the epitrochoid curve and the basic circle BCt are made common and the trochoid coefficient is larger than 1. As a result, the radii rde, rdh of the first and second drawing points, that is, the first and second radii are maintained while keeping the radii re, rh (radius / number of teeth of the heel base circle BCt) of the abduction circle Co and the inversion circle Ci. By increasing the second values Rde and Rdh, the shape of the tooth tip portion 21 and the tooth bottom portion 22 is determined using one basic circle BCt, and the outer diameter of the basic circle BCt, that is, the inner rotor 2 is kept small. The tooth height can be easily increased.

  Further, in the inner rotor 2 of the gear pump 1, the intermediate portion 23 between the tooth tip portion 21 and the tooth bottom portion 22 has a basic circle BCi that shares the center O with the basic circle BCt of the epitrochoid curve and the hypotrochoid curve. It is formed by the involute curve obtained by using. The intermediate portion 23 continues to the tooth tip portion 21 via a boundary portion 24 formed by a smooth curve (for example, an arc), and a tooth bottom portion via a boundary portion 25 formed by a smooth curve (for example, an arc). 22 is continuous. In this embodiment, the diameter of the base circle BCi of the involute curve forming the intermediate portion 23 is “Rbi”, and the epitrochoid curve forming the tip portion 21 and the hypotrochoid curve basic circle BCt forming the tooth bottom portion 22 When the diameter is “Rbt”, the diameters Rbt and Rbi of the base circles BCt and BCi are selected so as to satisfy the relationship Rbi ≦ Rbt. That is, when the diameter Rbi of the basic circle BCi of the involute curve, the diameter Rbt of the basic circle BCt of the epitrochoid curve and the hypotrochoid curve, and the eccentricity e satisfy such a relationship, the diameter of the basic circle BCt of the involute curve Since Rbi does not become larger than the diameter of the root circle of the inner rotor 2, even if the diameter of the base circle Rbt of the epitrochoid curve and hypotrochoid curve is reduced within the range satisfying this relationship, The portion 23 can be formed by an involute curve.

  Further, in the inner rotor 2 of the gear pump 1, the radius rde of the first drawing point for drawing the epitrochoid curve forming the tooth tip portion 21, that is, the first value Rde, and the hypotrochoid curve forming the tooth bottom portion 22. Is set to the same value Rd, and the radius re of the abduction circle Co and the radius rh of the inversion circle Ci are the same value. R. Therefore, in the inner rotor 2, the relationship Rde = Rdh = Rd, re = rh = R, and tooth height = Rde + re + Rdh + rh = 2 · e is established.

  On the other hand, the tooth profile (contour) of the outer rotor 3 defined by the plurality of inner teeth 30 is such that the rotation center 2c of the inner rotor 2 is centered on the rotation center 3c of the outer rotor 3 as shown in FIG. A plurality of tooth profile lines (inners) obtained by revolving one revolution at a predetermined angle δ on the circumference of e + t and rotating the inner rotor 2 by a rotation angle δ / N when the rotation center 2c revolves by a predetermined angle δ. It is determined based on the envelope drawn with respect to the contour of the rotor 2 (see the two-dot chain line in FIG. 5). However, “t” is the tooth of the external tooth 20 when the rotational center 2c of the inner rotor 2, the rotational center 3c of the outer rotor 3, the tooth tip 21t of the external tooth 20 and the tooth tip of the internal tooth 30 are positioned in a straight line. The clearance (tip clearance) between the tip 21t and the tip of the internal tooth 30 is, for example, a value of about 0.03 to 0.07 mm. As a result, it is possible to easily obtain the outer rotor 3 that can mesh properly with the inner rotor 2. The tooth profile (outline) of the outer rotor 3 may be the envelope itself, or may be determined so as to be located outside the envelope. The inner teeth of the outer rotor 3 may be created using a gear cutting tool having substantially the same shape as the inner rotor 2.

  As described above, in the inner rotor 2 of the gear pump 1, the tooth tip portion 21 and the tooth of the outer tooth 20 of the inner rotor 2 are caused by an epitrochoid curve or a hypotrochoid curve having a trochoid coefficient larger than the value 1 that makes the basic circle BC common. A bottom 22 is formed. In the inner rotor 2, the radius rde = Rde of the first drawing point for drawing the epitrochoid curve forming the tooth tip portion 21 and the second for drawing the hypotrochoid curve forming the tooth bottom portion 22. The radius rdh = Rdh of the drawing point is matched, and the radius re of the abduction circle and the radius rh of the inversion circle are matched, and Rde = Rdh = Rd, re = rh = R, and Rde + re + Rdh + rh = 2・ The relationship e is established.

  That is, the inventors of the present invention provide clearance between the tooth tips of the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 (between the tooth tip portion 21 of the outer teeth 20 and the tooth tip portion of the inner teeth 30). As a result of further research to ensure a more appropriate range in the tooth thickness direction in which the clearance) is kept relatively small, that is, the seal width, the tooth tip portion 21 and the tooth bottom portion 22 of the external tooth 20 are as described above. In the case of creation, Rde = Rdh = Rd, re = rh = R, and Rde + re + Rdh + rh = 2 · e so that the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 It has been found that the clearance between the tooth tips can be kept substantially constant over a wider range, that is, the seal width can be expanded. FIG. 3 shows an example of the relationship between the rotation angle ω around the rotation center 2 c of the inner rotor 2 in the gear pump 1 and the clearance (gap space) between the external teeth 20 and the internal teeth 30.

  3 shows that the diameter of the root circle of the inner rotor 2 is, for example, in the range of 50 to 60 mm, the diameter of the root circle of the outer rotor is in the range of, for example, 70 to 75 mm, and the eccentricity e is, for example, 2.5 to 3.5 mm. The analysis results are shown for the gear pump 1 in which the range, Rde = Rdh = Rd is selected from a range of 1.5 to 2 mm, for example, and re = rh = R is selected from a range of 1.0 to 1.5 mm, for example. Note that the rotation angle ω around the rotation center 2c of the inner rotor 2 in FIG. 3 is a direction toward the lower side in the drawing of a dashed line passing through the rotation center 2c of the inner rotor 2 and the rotation center 3c of the outer rotor 3 in FIG. It is measured counterclockwise in FIG. 1 as 0 (rad). Further, the clearance between the external teeth 20 and the internal teeth 30 is the minimum distance measured in the direction of the normal to the tooth surface of the external teeth 20 and the internal teeth 30 that are closest to each other as shown in FIG.

  As shown in FIG. 3, in the gear pump 1 including the inner rotor 2 satisfying Rde = Rdh = Rd, re = rh = R, and Rde + re + Rdh + rh = 2 · e, ω = π in FIG. The clearance between the external teeth 20 and the internal teeth 30 in the central range A (for example, 90 ° ≦ ω ≦ 270 °, including the region between the suction port 6 and the discharge port 7), that is, the external teeth of the inner rotor 2 The clearance between the tooth tips of the outer teeth 3 and the inner teeth 30 of the outer rotor 3 is kept substantially constant, and a good seal width is ensured. And the diameter of the root circle of the inner rotor 2 is in the range of, for example, 50 to 60 mm, the diameter of the root circle of the outer rotor is in the range of, for example, 70 to 75 mm, and the eccentricity e is in the range of, for example, 2.5 to 3.5 mm. A plurality of analysis results obtained by changing Rde = Rdh = Rd within a range of, for example, 1.5 to 2 mm and re = rh = R within a range of, for example, 1.0 to 1.5 mm are all shown in FIG. Similar characteristics were exhibited.

  Thereby, in the gear pump 1 described above, the external teeth 20 formed by the hypotrochoid curve that defines the tooth tips 21 of the external teeth 20 formed by the epitrochoid curve and the tooth tips of the internal teeth 30 of the outer rotor 3. The dimension of the tooth bottom portion 22 in the tooth thickness direction, that is, the range of rotation angles of the abduction circle Co and the inversion circle Ci for creating the tooth tip portion 21 (epitrochoid curve) and the tooth bottom portion 22 (hypotrochoid curve). It will be understood that by adjusting, the clearance between the tooth tips of the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 can be easily adjusted. Therefore, in the gear pump 1, the clearance between the external teeth 20 and the internal teeth 30 is reduced to ensure the sealing performance and the volume efficiency is improved, and the clearance between the external teeth 20 and the internal teeth 30 is ensured to some extent. It is possible to easily achieve both suppression of the occurrence of cavitation caused by this.

  Further, as a result of the study by the present inventors, in the gear pump 1 including the inner rotor 2 satisfying Rde = Rdh = Rd, re = rh = R, and Rde + re + Rdh + rh = 2 · e, the drawing points of the epitrochoid curve and the hypotrochoid curve Is less than 2.5 times the radius R of the abduction circle Co and the inversion circle Ci (Rd ≦ 2.5 · R), more preferably 1.5 to 2.0 times (1.5 · R ≦ Rd ≦ 2.0 · R), the clearance between the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 is substantially constant within a sufficiently wide range (seal width) in practice. It turns out that it can keep. Furthermore, as a result of the analysis by the present inventors, the tooth tip portion 21 of the outer tooth 20 of the inner rotor 2 is obtained by an epitrochoid curve or a hypotrochoid curve having a trochoid coefficient larger than the value 1 that shares the basic circle BC as described above. If the tooth bottom portion 22 is formed, the first and second values Rde and Rdh are not completely matched, and the radius re of the abduction circle Co and the radius rh of the inversion circle Ci are not completely matched. However, it was also confirmed that the range in the tooth thickness direction in which the clearance between the tooth tips of the outer teeth of the inner rotor and the inner teeth of the outer rotor is kept relatively small, that is, the seal width can be maintained satisfactorily.

  As described above, in the gear pump 1, the shape of the tooth tip portion 21 and the tooth bottom portion 22 of the outer teeth 20 of the inner rotor 2 is determined using one basic circle BC, and the basic circle BC (outer diameter of the inner rotor) is determined. The tooth thickness can be easily increased while keeping the teeth small, and the clearance between the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 is kept relatively small. The range in the direction, that is, the seal width can be maintained well. Therefore, in the gear pump 1, while suppressing increase in size and reduction in the number of teeth, the tooth height is easily increased to improve the discharge performance, and the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 It becomes possible to optimize the clearance.

  Further, like the inner rotor 2, if the intermediate portion 23 positioned between the tooth tip portion 21 and the tooth bottom portion 22 is formed by an involute curve, the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3. And the speed ratio between the inner rotor 2 and the outer rotor 3 can be made constant. However, the intermediate portion 23 located between the tooth tip portion 21 and the tooth bottom portion 22 is, for example, an n-order function (where “n” is an integer of 1 or more), an arbitrary polynomial, a trigonometric function, a relaxation Needless to say, it may be formed by a curve other than the involute curve such as a curve.

  Furthermore, in the gear pump 1 described above, each external tooth 20 of the inner rotor 2 is formed symmetrically with respect to a line segment connecting the tooth tip 21t of the tooth tip portion 21 and the rotation center 2c, and each inner tooth 30 of the outer rotor 3 is similarly formed. Is formed symmetrically with respect to a line segment connecting the tooth tip of the tooth tip portion and the rotation center 3c, but is not limited thereto. That is, each external tooth 20 of the inner rotor 2 may be formed asymmetrically with respect to a line segment connecting the tooth tip 21t of the tooth tip portion 21 (and the tooth bottom 22b of the tooth bottom portion 22) and the rotation center 2c. Each of the three internal teeth 30 may also be formed asymmetrically with respect to a line segment connecting the tip of the tooth tip (and the bottom of the tooth bottom) and the rotation center 3c. In this case, the tooth tip part 21, the intermediate part 23, and the tooth bottom part 22 on the front side (the left half of the external tooth 20 in FIG. 2) in the rotation direction of the inner rotor 2 of each external tooth 20 were created as described above. The inner teeth 30 of the outer rotor 3 may be created as described above. Further, when the intermediate portion 23 of the external tooth 20 is formed by an involute curve, the pressure angle in the intermediate portion 23 (involute curve) is changed between the front side and the rear side in the rotation direction of the inner rotor 2 of each external tooth 20. Also good. Thereby, the clearance between the inner rotor 2 and the outer rotor 3 can be adjusted.

  FIG. 6 is a schematic configuration diagram showing a gear pump 1B according to another modification of the present invention. The gear pump 1B shown in the figure communicates with the interdental chamber 5 that expands as the inner rotor 2 and the outer rotor 3 rotate among the interdental chambers 5 defined by the external teeth 20 and the internal teeth 30. One suction port 6 (facing) and two independent discharge ports communicating (opposite) with the interdental chamber 5 that contracts as the inner rotor 2 and the outer rotor 3 of the plurality of interdental chambers 5 rotate. 7a and 7b. That is, according to the present invention, while increasing the tooth length while suppressing the increase in size and the decrease in the number of teeth of the inner rotor 2 and the like, the discharge performance is improved, and the inner teeth of the inner rotor 2 and the outer rotor 3 are increased. Since the clearance with the teeth 30 can be optimized, a two-port gear pump 1B that is compact and has good discharge performance can be easily realized. In the gear pump 1B shown in FIG. 6, each outer tooth 20 of the inner rotor 2 and each inner tooth 30 of the outer rotor 3 are formed asymmetrically with respect to a line segment connecting the tooth tip of the tooth tip portion and the rotation center 2c or 3c. May be.

  Although the embodiment of the present invention has been described above, the present invention is not limited to the above embodiment, and it goes without saying that various modifications can be made without departing from the scope of the present invention. . In addition, the correspondence between the main elements of the above embodiment and the main elements of the invention described in the column of means for solving the problem is described in the column of means for solving the problem by the embodiment. Since the embodiment for carrying out the invention is an embodiment for specifically explaining the invention, the elements of the invention described in the column of means for solving the problems are not limited. That is, the above embodiment is merely a specific form of the invention described in the section for solving the problem, and the interpretation of the invention described in the section for solving the problem is This should be done based on the description in the column.

  The present invention can be used in the gear pump manufacturing industry.

  1,1B Gear pump, 2 Inner rotor, 2c, 3c Center of rotation, 3 Outer rotor, 4 Rotating shaft, 5 Interdental chamber, 6 Suction port, 7, 7a, 7b Discharge port, 20 External teeth, 21 Tooth tip, 21t Tooth tip, 22 Tooth bottom portion, 22b Tooth bottom, 23 Intermediate portion, 24, 25 Boundary portion, 30 Internal teeth.

Claims (8)

In a gear pump comprising an inner rotor having a plurality of external teeth, and an outer rotor having a plurality of internal teeth larger than the outer teeth of the inner rotor and arranged to be eccentric with respect to the inner rotor,
Each of the outer teeth of the inner rotor is obtained by rolling at least on the front side in the rotational direction of the inner rotor without slipping while making an outer circle having a radius smaller than the radius of the drawing point circumscribe the base circle. Hypothesis obtained by rolling a tooth tip formed by an epitrochoid curve and an inversion circle having a radius smaller than the radius of the drawing point without slipping while inscribed in the base circle common to the epitrochoid curve A gear pump comprising: a tooth bottom portion formed by a trochoid curve; and an intermediate portion formed by an arbitrary curve and positioned between the tooth tip portion and the tooth bottom portion. The gear pump according to claim 1, wherein
The inner rotor has a radius of the drawing point of the epitrochoid curve and a radius of the abduction circle of “rde” and “re”, respectively, and the radius of the drawing point of the hypotrochoid curve and the radius of the inversion circle When the radius is “rdh” and “rh” respectively,
rde = rdh = Rd, re = rh = R
A gear pump characterized by being configured to satisfy. The gear pump according to claim 2,
The inner rotor is
Rd ≦ 2.5 ・ R
A gear pump characterized by being configured to satisfy. The gear pump according to any one of claims 1 to 3,
The intermediate portion is formed by an involute curve. The gear pump according to claim 4,
In the inner rotor, the diameter of the foundation circle of the epitrochoid curve and the hypotrochoid curve is “Rbt”, the diameter of the foundation circle of the involute curve is “Rbi”, and the outer rotor with respect to the rotation center of the inner rotor When the amount of eccentricity at the center of rotation is “e”,
Rbi ≦ Rbt
A gear pump characterized by being configured to satisfy. In the gear pump according to any one of claims 1 to 5,
One suction port communicating with an interdental chamber that expands as the inner rotor and the outer rotor rotate among a plurality of interdental chambers defined by the external teeth and the internal teeth;
Two independent discharge ports communicating with the interdental chamber that contracts with rotation of the inner rotor and the outer rotor of the plurality of interdental chambers;
A gear pump further comprising: The gear pump according to any one of claims 1 to 6,
The tooth profile of the outer rotor defined by the plurality of internal teeth is “e” as the amount of eccentricity of the rotation center of the outer rotor with respect to the rotation center of the inner rotor, and the rotation center of the inner rotor and the outer rotor When the clearance between the tooth tip of the external tooth and the tooth tip of the internal tooth when the rotational center, the tooth tip of the external tooth and the tooth tip of the internal tooth are positioned in a straight line is “t”, The rotation center of the inner rotor is revolved by a predetermined angle on a circumference of a diameter of 2 · e + t centered on the rotation center of the outer rotor, and the inner rotor 2 is moved when the rotation center of the inner rotor revolves by a predetermined angle. It is determined based on an envelope drawn with respect to a plurality of tooth profile lines obtained by rotating by the predetermined angle and a rotation angle corresponding to the number of teeth of the inner rotor. Gear pump, wherein the door. In the method of manufacturing an inner rotor that has a plurality of external teeth and is arranged to be eccentric with respect to the outer rotor having a plurality of internal teeth larger than the external teeth and constitutes a gear pump together with the outer rotor.
The tooth is formed by an epitrochoid curve obtained by rolling an abduction circle having a radius smaller than the radius of the drawing point on the front side of at least the inner rotor in the rotational direction of each of the outer teeth without slipping while circumscribing the base circle. A hypotrochoid curve obtained by rolling an inversion circle having a radius smaller than the drawing point radius while inscribed in the basic circle common to the epitrochoid curve and forming a tip portion without slipping And an intermediate portion located between the tooth tip portion and the tooth bottom portion is formed by an arbitrary curve.

Images