JP6599181B2 - Gear pump - Google Patents

Description

  The present disclosure relates to a gear pump including an inner rotor having a plurality of external teeth and an outer rotor having a plurality of internal teeth and arranged to be eccentric with respect to the inner rotor.

  Conventionally, a gear pump including an inner rotor having n external teeth, an outer rotor having n + 1 internal teeth meshing with the external teeth, and a casing in which a suction port and a discharge port are formed is known. (For example, refer to Patent Document 1). In this gear pump, the first angle formed by the first straight line connecting the rotation center of the inner rotor and the tooth tip of the external tooth and the second straight line connecting the rotation center and the meshing portion of the external tooth is the rotation center and the external tooth. It is set to 1.4 times or more and 1.8 times or less of the second angle formed by the third straight line connecting the tooth bottom and the second straight line. Furthermore, the width along the rotation direction of the meshing portion of the external teeth is equal to the distance between the rear end in the rotation direction of both rotors of the suction port and the front end in the rotation direction of the discharge port, that is, the partition width of the port. .

Japanese Patent No. 4889981

  In Patent Document 1, by setting the first angle to be 1.4 times or more and 1.8 times or less of the second angle, both rotors of a plurality of cells (interdental chambers) mesh with each other from the outer teeth. It is described that it is possible to prevent the occurrence of so-called fluid confinement, in which the minimum volume cell located at the meshing position where the rotational driving force is transmitted to the teeth is sealed. However, even if the configuration described in Patent Document 1 is adopted, the gap between the case and both rotors (the gap in the axial direction of the gear pump) with respect to a cell whose volume is minimized by discharging fluid to the discharge port. It is difficult to completely suppress the inflow of fluid. Therefore, in the gear pump of Patent Document 1, cavitation occurs due to the fluid flowing at high speed from the gap between the case and both rotors into the interdental chamber that does not communicate with the discharge port and communicates with the suction port. There is a fear.

  Accordingly, the main object of the present disclosure is to provide a gear pump that can satisfactorily suppress the occurrence of cavitation in the interdental chamber that does not communicate with the discharge port and communicates with the suction port.

  The gear pump of the present disclosure has a suction port, a discharge port, an inner rotor having a plurality of external teeth, a plurality of internal teeth that are larger than the external teeth of the inner rotor, and is eccentric with respect to the inner rotor. And a plurality of interdental chambers defined by the plurality of external teeth and the plurality of internal teeth, the discharge port is configured to rotate the inner rotor and the outer rotor. The interdental chamber communicated with the interdental chamber, the volume of which decreases along with the discharge port, and communicated with the suction port while the volume of the interdental chamber decreased, and communicated with the discharge port. The volume of the interdental chamber that is no longer increased increases after at least a part of the interdental chamber communicates with the suction port.

  In this gear pump, the interdental chamber that has stopped communicating with the discharge port communicates with the suction port while the volume of the interdental chamber decreases with the rotation of the inner rotor and the outer rotor. As a result, the volume of the interdental chamber that is no longer in communication with the discharge port decreases with the rotation of the inner rotor or the like, so that fluid is discharged from the interdental chamber to the suction port. The volume of the interdental chamber that is no longer in communication with the discharge port increases after the interdental chamber communicates with the suction port. That is, the volume of the interdental chamber that is no longer in communication with the discharge port is minimized after the interdental chamber communicates with the suction port. As a result, the fluid flowing into the suction port from the interdental chamber that is no longer in communication with the discharge port causes fluid to flow into the interdental chamber from the gap between the inner rotor and the outer rotor and the member that accommodates both (axial gap). Inflow at high speed can be well controlled. Therefore, in this gear pump, it is possible to satisfactorily suppress the occurrence of cavitation in the interdental chamber that does not communicate with the discharge port and communicates with the suction port.

It is a schematic structure figure showing a gear pump of this indication. It is a schematic block diagram which shows the external tooth of the inner rotor contained in the gear pump of this indication. It is a schematic diagram which shows the creation procedure of the external tooth of the inner rotor contained in the gear pump of this indication. It is a schematic diagram which shows the creation procedure of the internal tooth of the outer rotor contained in the gear pump of this indication. It is an enlarged view for demonstrating operation | movement of the gear pump of this indication. It is an enlarged view for demonstrating operation | movement of the gear pump of this indication. It is an enlarged view for demonstrating operation | movement of the gear pump of this indication. It is a graph which illustrates the relationship between the rotation angle around the rotation center of an inner rotor, and the volume of the interdental chamber which is no longer connected to a discharge port. It is an enlarged view for demonstrating operation | movement of the gear pump which concerns on other embodiment of this indication.

  Next, embodiments for carrying out the invention of the present disclosure will be described with reference to the drawings.

  FIG. 1 is a schematic configuration diagram illustrating a gear pump 1 according to an embodiment of the present disclosure. A gear pump 1 shown in the figure is configured as an oil pump mounted on a vehicle (not shown), for example, and sucks hydraulic oil (ATF) stored in an oil pan and pumps it to a hydraulic control device (both not shown). To do. The gear pump 1 is defined by, for example, a pump housing (both not shown) constituted by a pump body fixed to a transmission case of an automatic transmission and a pump cover fastened to the pump body, and the pump housing. An inner rotor (drive gear) 2 and an outer rotor (driven gear) 3 that are rotatably arranged in a gear housing chamber (not shown). The gear pump 1 may be configured as an in-vehicle pump (for example, an engine oil pump) other than an oil pump that pumps hydraulic oil for transmission, and may be applied to uses other than the in-vehicle pump.

  The inner rotor 2 is fixed to a rotating shaft 4 connected to a crankshaft (both not shown) of an engine mounted on the vehicle, and is rotated by power applied to the rotating shaft 4. A plurality of (for example, 11 teeth in this embodiment) external teeth 20 are formed on the outer periphery of the inner rotor 2. On the other hand, on the inner periphery of the outer rotor 3, the number of internal teeth 30 that is one more than the total number of external teeth 20 of the inner rotor 2 (for example, 12 teeth in this embodiment) is formed. The outer rotor 3 is configured so that any one or a plurality of inner teeth 30 located on the lower side in FIG. 1 mesh with the corresponding outer teeth 20 of the inner rotor 2 and are eccentric with respect to the inner rotor 2. It is rotatably arranged in the storage chamber. Furthermore, a plurality of interdental chambers (pump chambers) 5 are basically formed between the inner rotor 2 and the outer rotor 3 by two adjacent external teeth 20 and two adjacent internal teeth 30. .

  Thereby, when the inner rotor 2 is rotated in the direction of the thick arrow in FIG. 1 by the power from the rotating shaft 4, the outer rotor 3 has a part of the plurality of inner teeth 30 meshed with a part of the plurality of outer teeth 20. Thus, it rotates in the same direction together with the inner rotor 2 around the rotation center 3c that is separated from the rotation center 2c of the inner rotor 2 by the eccentric amount e. When the inner rotor 2 and the outer rotor 3 are rotated, in the rear region in the rotation direction of the both (see the thick arrow in FIG. 1), that is, mainly in the right half region in FIG. Thus, the volume of each interdental chamber 5 increases (interdental chamber 5 expands). Further, when the inner rotor 2 and the outer rotor 3 rotate, in the front region in the rotation direction of the inner rotor 2 or the like, that is, mainly the left half region in FIG. The volume of the chamber 5 decreases (the interdental chamber 5 contracts).

  A pump housing (not shown) of the gear pump 1 is formed with a suction port 6, a first discharge port 7, and a second discharge port 8 each extending in a substantially arc shape. The suction port 6 communicates with the interdental chamber 5 whose volume increases 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 ( opposite. The first and second discharge ports 7 and 8 are separated by a partition wall 9 and are independent from each other, and the teeth whose volumes decrease as the inner rotor 2 and the outer rotor 3 of the plurality of interdental chambers 5 rotate. It communicates (opposites) with the inter-chamber 5 respectively. In the present embodiment, the first discharge port 7 located on the rear side in the rotation direction of the inner rotor 2 or the like is a low pressure port, and the second discharge port 8 located on the front side in the rotation direction is a high pressure port.

  In addition, the 1st and 2nd discharge ports 7 and 8 may be connected to a mutually different oil path, and may be connected to a common oil path. The suction port 6, the first and second discharge ports 7, 8 may be formed on both sides (both the pump body and the pump cover) in the axial direction of the inner rotor 2 and the outer rotor 3, The outer rotor 3 may be formed on one side (one of the pump body and the pump cover) in the axial direction. Further, for example, the suction port 6 may be formed on one side in the axial direction of the inner rotor 2 or the like, and the first and second discharge ports 7 and 8 are formed on the other side in the axial direction of the inner rotor 2 or the like. Also good. Further, the first discharge port 7 may be formed on one side in the axial direction of the inner rotor 2 or the like, and the second discharge port 8 may be formed on the other side in the axial direction of the inner rotor 2 or the like.

  FIG. 2 is a schematic configuration diagram showing the external teeth 20 of the inner rotor 2, and FIG. 3 is a schematic diagram showing a procedure for creating the external teeth 20. As shown in these drawings, each external tooth 20 of the inner rotor 2 includes a convexly curved tooth tip portion 21, a concave curved tooth bottom portion 22, and the rotational direction of the inner rotor 2 relative to the tooth tip portion 21 ( The first intermediate portion 23 located between the tooth tip portion 21 and the tooth bottom portion 22 on the front side in the thick arrow in FIG. 3, and the tooth on the rear side in the rotational direction of the inner rotor 2 relative to the tooth tip portion 21. A second intermediate portion 24 located between the tip portion 21 and the tooth bottom portion 22 is included. As shown in the drawing, the external teeth 20 are formed asymmetrically with respect to a tooth profile center line Lc passing through the top portion 21t located on the outermost radial direction of the tooth tip portion 21 and the rotation center 2c of the inner rotor 2.

  As shown in FIG. 3, the tooth tip portion 21 has a trochoidal coefficient obtained by dividing the radius rde of the first drawing point by the radius re of the abduction circle Co, which is larger than 1 (for example, about 1.2). Value) A convex curved surface is formed by an epitrochoid curve (a portion other than the loop portion). 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 an abduction circle Co having a radius re smaller than the first value Rde. Is rolled without slipping while circumscribing the base circle BCt having the rotation center 2c of the inner rotor 2 and the center O in common.

  The root portion 22 is an intermediate formed by a hypotrochoid curve (a portion other than the loop portion) having a trochoid coefficient larger than 1 obtained by dividing the radius rdh of the second drawing point by the radius rh of the inversion circle Ci. Part and two rising parts formed by a curve such as an arc. The hypotrochoid curve forming the middle portion of the tooth bottom portion 22 shares the epitrochoid curve forming the tooth tip portion 21 with the basic circle BCt, and as shown in FIG. 3, the radius of the second drawing point It is obtained by keeping rdh at the second value Rdh (constant value) and rolling the inversion circle Ci having a radius rh smaller than the second value Rdh without slipping while inscribed in the basic circle BCt. . In the present embodiment, 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 are drawn. For this reason, the radius rdh of the second drawing point, that is, the second value Rdh is set to the same value Rd. Similarly, the radius re of the abduction circle Co and the radius rh of the inversion circle Ci are set to 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.

  The two rising portions of the tooth bottom portion 22 extend from the intermediate portion toward the corresponding first or second intermediate portions 23 and 24 so as to smoothly continue to the intermediate portion formed by the hypotrochoidal curve. The rear rising portion in the rotation direction of the inner rotor 2 is formed so as to smoothly continue to the first intermediate portion 23 at the front end portion 23f of the first intermediate portion 23 in the rotation direction. The front rising portion in the second rotational direction is formed so as to be smoothly continuous with the second intermediate portion 24 at the rear end 24r of the second intermediate portion 24 in the rotational direction. Thereby, the intermediate part formed by the hypotrochoid curve of the tooth bottom part 22 is offset to the center O (rotation center 2c of the inner rotor 2) side from the basic circle BCt. Further, the tooth bottom portion 22 is frontward in the rotational direction from the tooth profile center line Lc by a half (φ / 2) of an angle φ (360 ° / the number of teeth of the external teeth 20) corresponding to one tooth of the external teeth 20. Alternatively, an intersection 22x with the line segment Le rotated to the rear side is included. In the inner rotor 2, as shown in FIGS. 2 and 3, a range between the two intersecting portions 22 x sandwiching the tooth profile center line Lc is a range corresponding to one tooth of the external teeth 20.

  As shown in FIGS. 2 and 3, the first intermediate portion 23 is formed between the tooth tip portion 21 and the front tooth bottom portion 22 of the tooth tip portion 21 in the rotation direction of the inner rotor 2. In the present embodiment, the first intermediate portion 23 is determined such that the tangent at the front end 21f in the rotation direction of the tooth tip 21 is common to the tangent of the epitrochoidal curve at the end 21f. Formed by an involute curve. Thereby, the tip part 21 and the 1st intermediate part 23 can be smoothly continued in the edge part 21f. In the present embodiment, the length of the involute curve forming the first intermediate portion 23, that is, the length from the end portion 21 f of the tooth tip portion 21 to the end portion 23 f of the first intermediate portion 23 is the same as that of the second intermediate portion 24. The length of the curve to be formed, that is, the length from the end portion 21r of the tooth tip portion 21 to the end portion 24r of the second intermediate portion 24 is determined.

  As shown in FIGS. 2 and 3, the second intermediate portion 24 is formed between the tooth tip portion 21 and the rear tooth bottom portion 22 in the rotational direction of the inner rotor 2 of the tooth tip portion 21. The second intermediate portion 24 includes an outer intermediate portion 24o located on the tooth tip portion 21 side with respect to the intersection portion 24x with the basic circle BCt, and an inner intermediate portion 24i located on the tooth bottom portion 22 side with respect to the intersection portion 24x. Including. In the present embodiment, the range from the outer intermediate portion 24o, that is, the intersecting portion 24x to the rear end portion (boundary) 21r in the rotation direction of the inner rotor 2 of the tooth tip portion 21, as shown in FIG. It is formed by a first curve obtained by rolling an outer rotation circle Co circumscribing the base circle BCt without slipping while changing the radius of one drawing point (see the dotted line in the figure). Further, as shown in FIG. 3, the inner intermediate portion 24i, that is, the range from the intersecting portion 24x to the end portion 24r, is changed to the basic circle BCt while changing the radius of the second drawing point (see the two-dot chain line in the drawing). It is formed by the second curve obtained by rolling the inscribed inversion circle Ci without slipping. For the procedure for changing the radius of the first or second drawing point of the abduction circle Co or the inversion circle Ci, refer to Japanese Patent Application Laid-Open No. 2014-181619.

  FIG. 4 is a schematic diagram showing a procedure for creating the inner teeth 30 of the outer rotor 3 included in the gear pump 1. As shown in the figure, the tooth profile (outline) of the outer rotor 3 defined by the plurality of inner teeth 30 is the rotation center 2c of the inner rotor 2Z based on the inner rotor 2 and the rotation center 3c of the outer rotor 3. Obtained by rotating the inner rotor 2Z 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 a plurality of tooth profile lines (the outline of the inner rotor 2, see the two-dot chain line in FIG. 3). However, “t” indicates that the rotation center 2c of the inner rotor 2Z, the rotation center 3c of the outer rotor 3, the top part 21t of the tooth tip part 21 of the external tooth 20 and the top part of the tooth tip part of the internal tooth 30 are aligned. This is the clearance (tip clearance) between the top 21t and the top of the internal teeth 30, for example, about 0.03 to 0.07 mm.

  The inner rotor 2Z for defining the tooth profile of the outer rotor 3 corresponds to a structure in which the tooth bottom portion 22 of the inner rotor 2 is replaced with a tooth bottom portion 22z indicated by a two-dot chain line in FIGS. 2 and 3, the tooth bottom portion 22z is the end of the second intermediate portion 24 formed by the same hypotrochoidal curve (portion other than the loop portion) that forms the intermediate portion of the tooth bottom portion 22, as shown in FIGS. A portion from the portion 24r to the boundary portion 22y shown in FIGS. 2 and 3 and a portion from the boundary portion 22y formed by a smooth curve (for example, an arc) to the end portion 23f of the first intermediate portion 23 are included. As a result, it is possible to easily obtain the outer rotor 3 that can mesh properly with the inner rotor 2. However, the tooth profile (outline) of the outer rotor 3 may be the envelope itself or may be determined to be located outside the envelope. Further, 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 2Z.

  In the gear pump 1, the inner rotor 2 (specifications of the external teeth 20), the outer rotor 3, the suction port 6, the first and second discharge ports 7, 8 are not connected to the second discharge port 8. The chamber 5x (see FIG. 1) communicates with the suction port 6 while the volume of the interdental chamber 5x is decreasing, and after the communication between at least a part of the interdental chamber 5x and the suction port 6, the volume of the interdental chamber 5x Is configured to increase. In addition, in the gear pump 1, the top dead center (a position where the top of the tooth tip 21 of the external tooth 20 and the top of the tooth tip of the internal tooth 30 face each other in a straight line) is closest. While one external tooth 20 is in contact with the corresponding internal tooth 30, the external tooth 20 located on the back side in the rotation direction of any one of the external teeth 20 is in contact with the corresponding internal tooth 30. As described above, the plurality of external teeth 20 of the inner rotor 2 are formed. By determining the specifications of the tooth tip portion 21, the tooth bottom portion 22, the first and second intermediate portions 23, 24, etc. so as to satisfy such conditions, the occurrence of cavitation in the interdental chamber 5 (5x) is satisfactorily suppressed. At the same time, the behavior of the inner rotor 2 and the outer rotor 3 during operation of the gear pump 1 can be stabilized to reduce vibration and noise.

  Next, the operation of the gear pump 1 will be described with reference to FIGS. 5 to 7 are enlarged views for explaining the operation of the gear pump 1, and FIG. 8 is a diagram illustrating the rotation angle θ around the rotation center 2c of the inner rotor 2 and the interdental teeth that do not communicate with the second discharge port 8. It is a graph which illustrates the relationship with the volume V of the chamber 5x. Note that the rotation angle θ of the inner rotor 2 is a rotation angle around the rotation center 2c of the line portion connecting the bottommost portion (deepest portion) of the tooth bottom portion 22 of the certain external tooth 20 and the rotation center 2c. Measurement is performed counterclockwise in FIG. 1 with 0 ° being the state in which the bottom of the bottom portion 22 of the external tooth 20 is located directly below the center of rotation 2c.

  In the gear pump 1, the volume V of each interdental chamber 5 communicating with the second discharge port 8 decreases as the inner rotor 2 and the outer rotor 3 rotate. Then, when the rotation angle θ of the inner rotor 2 becomes the first angle θ1 (see FIG. 8), the rotation direction that defines the interdental chamber 5x communicating with the second discharge port 8, as shown in FIG. The meshing portion E of the rear external teeth 20 and the internal teeth 30 overlaps the peripheral edge 8e of the second discharge port 8 when viewed from the axial direction of the inner rotor 2, so that the interdental chamber 5x and the second discharge port 8 communicate with each other. Will be refused. Further, when the meshing portion E overlaps with the peripheral edge 8e of the second discharge port 8 and the interdental chamber 5x is not communicated with the second discharge port 8, the inner rotor 2 is more than the outer teeth 20 including the meshing portion E. As shown in FIG. 5, the tooth surface (the tooth bottom portion 22 or the second intermediate portion 24) of the outer tooth 20 on the immediately preceding side in the rotational direction is slightly different from the peripheral edge 6e of the suction port 6 when viewed from the axial direction of the inner rotor 2. get over. As a result, the interdental chamber 5x communicates with the suction port 6 almost at the same time as it does not communicate with the second discharge port 8.

  After the interdental chamber 5x does not communicate with the second discharge port 8 and communicates with the suction port 6, the volume V of the interdental chamber 5x increases with the rotation of the inner rotor 2 and the outer rotor 3, as shown in FIG. Will further decrease. Further, the communication area between the interdental chamber 5x and the suction port 6 as viewed from the axial direction of the inner rotor 2 gradually increases as the inner rotor 2 and the outer rotor 3 rotate, as shown in FIG. Further, in the present embodiment, when the rotation angle θ of the inner rotor 2 becomes the second angle θ2 (see FIG. 8), the entire interdental chamber 5x communicates with the suction port 6 as shown in FIGS. (The entire interdental chamber 5x overlaps the suction port 6 when viewed from the axial direction), and the volume V of the interdental chamber 5x becomes the minimum value Vmin.

  Further, when the volume of the interdental chamber 5x reaches the minimum value Vmin, the tooth bottom portion 22 between the two external teeth 20 defining the interdental chamber 5x is formed in the axial direction of the inner rotor 2 as shown in FIG. When viewed from the inner peripheral edge 6ie of the suction port 6, the suction port 6 does not protrude toward the rotation center 2c and is close to (substantially contacts) the inner peripheral edge 6ie. Then, after the volume V of the interdental chamber 5x reaches the minimum value Vmin, the volume V of the interdental chamber 5x increases as the inner rotor 2 and the outer rotor 3 rotate as shown in FIG. Thus, the hydraulic oil is sucked into the interdental chamber 5x from the suction port 6.

  As described above, in the gear pump 1, the interdental chamber 5 x that is no longer communicated with the second discharge port 8 is reduced while the volume V of the interdental chamber 5 x decreases as the inner rotor 2 and the outer rotor 3 rotate. It communicates with the suction port 6. As a result, the volume V of the interdental chamber 5x that is no longer in communication with the second discharge port 8 decreases with the rotation of the inner rotor 2 or the like, so that the hydraulic oil remaining in the interdental chamber 5x is sucked. It is discharged to port 6. Then, the volume V of the interdental chamber 5x that has stopped communicating with the second discharge port 8 begins to increase after the interdental chamber 5x has completely communicated with the suction port 6. That is, the volume V of the interdental chamber 5x that is no longer communicated with the second discharge port 8 becomes the minimum value Vmin after the interdental chamber 5x is completely communicated with the suction port 6.

  As a result, the gap between the inner rotor 2 and the outer rotor 3 and at least one of the pump body and the pump housing due to the hydraulic fluid flowing out from the interdental chamber 5x that is no longer in communication with the second discharge port 8 to the suction port 6. It is possible to satisfactorily restrict the hydraulic oil (leakage oil) from flowing into the narrow interdental chamber 5x from the (gap in the axial direction of the inner rotor 2) at high speed. Therefore, in the gear pump 1, it is possible to satisfactorily suppress the occurrence of cavitation in the interdental chamber 5x that does not communicate with the second discharge port 8 and communicates with the suction port 6.

  In the gear pump 1, the interdental chamber 5 x whose volume V decreases with the rotation of the inner rotor 2 and the outer rotor 3 is a meshing portion between the external teeth 20 and the internal teeth 30 that define the interdental chamber 5 x. When E overlaps with the peripheral edge 8e of the second discharge port 8 when viewed from the axial direction of the inner rotor 2, the E is not communicated with the second discharge port 8. In the gear pump 1, when the meshing portion E overlaps the peripheral edge 8 e of the second discharge port 8 as viewed from the axial direction of the inner rotor 2, the rotational direction of the inner rotor 2 is greater than the external teeth 20 including the meshing portion E. The tooth surface (the second intermediate portion 24 or the tooth bottom portion 22) of the outer tooth 20 on the immediately preceding side overlaps the peripheral edge 6e of the suction port 6 when viewed from the axial direction. As a result, the interdental chamber 5x whose volume V decreases with the rotation of the inner rotor 2 or the like is communicated with the suction port 6 immediately after it stops communicating with the second discharge port 8, and the hydraulic oil in the interdental chamber 5x Can flow out to the suction port 6. Therefore, with respect to the interdental chamber 5x that is no longer in communication with the second discharge port 8, a narrow interdental chamber 5x is formed from the gap between the inner rotor 2 and the outer rotor 3 and at least one of the pump body and the pump housing. It is possible to very well regulate the flow of hydraulic oil (leakage oil) at high speed.

  Further, in the gear pump 1, the volume V of the interdental chamber 5 x that has stopped communicating with the second discharge port 8 starts to increase after the entire interdental chamber 5 x communicates with the suction port 6. As a result, the interdental chamber 5x and the suction port 6 when the hydraulic oil starts to flow from the suction port 6 according to the increase in the volume V with respect to the interdental chamber 5x that is no longer in communication with the second discharge port 8. It can suppress that a communication area narrows. As a result, it is possible to suppress an increase in the flow velocity of the hydraulic oil flowing into the interdental chamber 5x from the suction port 6 and to satisfactorily suppress the occurrence of cavitation accompanying the suction of the hydraulic oil into the interdental chamber 5x. .

  Further, in the gear pump 1, as described above, the intermediate portion formed by the hypotrochoidal curve of each tooth bottom portion 22 of the inner rotor 2 is offset to the center O (rotation center 2c) side from the basic circle BCt, and the tooth The bottom 22 is deeper than that originally corresponding to the inner teeth 30 of the outer rotor 3. In addition, as shown in FIG. 7, the tooth bottom portion 22 between the two external teeth 20 that defines the interdental chamber 5x that is no longer in communication with the second discharge port 8 has a minimum volume V of the interdental chamber 5x. When Vmin is reached, when viewed from the axial direction of the inner rotor 2, the suction port 6 approaches the inner peripheral edge without protruding from the inner peripheral edge 6ie to the rotation center 2c side. As a result, the interdental chamber 5x and the suction port 6 when the hydraulic oil starts to flow from the suction port 6 according to the increase in the volume V to the interdental chamber 5x that is no longer in communication with the second discharge port 8. The communication area can be increased. Accordingly, it is possible to suppress the occurrence of cavitation accompanying the suction of the hydraulic oil into the interdental chamber 5x by suppressing the increase in the flow velocity of the hydraulic oil flowing from the suction port 6 into the interdental chamber 5x. .

  Further, in the gear pump 1, the tooth tip portion 21 of each external tooth 20 of the inner rotor 2 is formed by a portion other than the loop portion of the epitrochoid curve having a trochoid coefficient larger than 1. In addition, the tooth bottom portion 22 of the inner rotor 2 is formed by a portion other than the hypotrochoid curve loop 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 outer diameter of the inner rotor 2 is reduced. It is possible to easily increase the tooth height of the external teeth 20 while keeping it.

  By increasing the tooth height of the external teeth 20 in this way, with respect to a straight line passing through the rotation center 2c of the inner rotor 2 and the rotation center 3c of the outer rotor 3 (see the one-dot chain line extending in the vertical direction in FIG. 1), The meshing portion E between the external teeth 20 and the internal teeth 30 (the locus of the meshing portion E indicated by a dotted line in FIGS. 5 to 7) can be shifted to the rear side in the rotational direction of the inner rotor 2 and the like. Accordingly, the end portion on the rear side in the rotation direction of the suction port 6 is brought closer to the end portion on the front side in the rotation direction of the second discharge port 8, so that the interdental chamber 5 x that is no longer in communication with the second discharge port 8 can be easily filled. It is possible to communicate with the suction port 6 while V is decreasing.

  Further, by making the length of the curve forming the first intermediate portion 23 of the external teeth 20 longer than the length of the curve forming the second intermediate portion 24 and making the external teeth 20 asymmetrical, the tooth tip portion 21 ( The end portion 21r on the rear side in the rotation direction of the epitrochoid curve) can be brought closer to the bottom portion 22, and the end portion 21f on the front side in the rotation direction of the tooth tip portion 21 can be moved outward in the radial direction of the inner rotor 2. Then, by bringing the end portion 21r on the rear side in the rotation direction of the tooth tip portion 21 closer to the tooth bottom portion 22, the external teeth 20 that define the interdental chamber 5 communicating with the first and second discharge ports 7 and 8; It is possible to reduce the minimum clearance with the internal teeth 30 as a whole. Further, by bringing the end portion 21 f on the front side in the rotation direction of the tooth tip portion 21 to the outside in the radial direction of the inner rotor 2, the external teeth 20 and the internal teeth 30 that define the interdental chamber 5 communicating with the suction port 6. The minimum value of the clearance can be increased as a whole. As a result, it is possible to improve the degree of freedom in determining the position of the partition wall 9 that partitions the first and second discharge ports 7, 8, that is, the distribution ratio of the discharge flow rate from the first and second discharge ports 7, 8. It is possible to further reduce the minimum clearance (discharge-side clearance) between the external teeth 20 and the internal teeth 30 that overlap with each other. In addition, it is possible to sufficiently suppress the occurrence of cavitation in the interdental chamber 5 by sufficiently increasing the minimum clearance (suction side clearance) in the interdental chamber 5 where the volume change amount is maximum. .

  Furthermore, in the gear pump 1, the 1st intermediate part 23 located in the front side in the rotation direction of the inner rotor 2 of the tooth tip part 21 is formed of an involute curve. Thereby, it becomes possible to mesh the outer teeth 20 of the inner rotor 2 and the inner teeth 30 of the outer rotor 3 more smoothly and to make the rotation speed ratio between the inner rotor 2 and the outer rotor 3 constant. However, the first intermediate unit 23 is an involute curve such as an n-order function (where “n” is an integer equal to or greater than 1), an arc, an arbitrary polynomial, a trigonometric function, a relaxation curve, and a combination thereof. Needless to say, it may be formed by other curves.

  Note that the second intermediate section 24 is also an involute curve such as an n-order function (where “n” is an integer greater than or equal to 1), an arc, an arbitrary polynomial, a trigonometric function, a relaxation curve, and a combination thereof. Needless to say, it may be formed by other curves. The gear pump 1 may have a single discharge port. Furthermore, each external tooth 20 of the inner rotor 2 may be formed symmetrically with respect to the tooth profile center line Lc. The interdental chamber 5x communicates with the suction port 6 at a timing such that the interdental chamber 5x does not communicate with the suction port 6 while the interdental chamber 5x communicates with the second discharge port 8. The timing may be slightly later than the timing at which communication with the discharge port 8 stops. That is, both timings do not necessarily have to coincide completely. Furthermore, as shown in FIG. 9, the inner rotor 2, the second discharge port 8, and the input port 6 have a meshing portion E between the external teeth 20 and the internal teeth 30 that define the interdental chamber 5 x. The interdental chamber 5x may be formed so as to communicate with the suction port 6 before it overlaps the peripheral edge 8e of the inner rotor 2 when viewed from the axial direction. That is, the timing at which the interdental chamber 5x communicates with the suction port 6 is compared with the timing at which the interdental chamber 5x does not communicate with the second discharge port 8 within a range that does not significantly affect the discharge pressure from the second discharge port 8. May be slightly faster. As a result, the interdental chamber 5x, whose volume decreases with the rotation of the inner rotor 2 or the like, is communicated with the suction port 6 before it stops communicating with the second discharge port 8, and an appropriate amount of operation in the interdental chamber 5x is achieved. Oil can flow out to the second discharge port 8 and the suction port 6. As a result, it is possible to hold the hydraulic oil pressure in the interdental chamber 5x so as not to increase more than necessary, and to suppress the occurrence of vibration due to the hydraulic oil pressure increase in the interdental chamber 5x. .

  As described above, the gear pump (1) of the present disclosure includes the suction port (6), the discharge port (7, 8), the inner rotor (2) having a plurality of external teeth (20), and the inner rotor. An outer rotor (3) having a plurality of inner teeth (30) larger than the outer teeth (20) of (2) and arranged to be eccentric with respect to the inner rotor (2), and the plurality of outer teeth In a gear pump (1) including a tooth 20) and a plurality of interdental chambers (5) defined by the plurality of internal teeth (30), the discharge port (7, 8) is connected to the inner rotor (2). The interdental chamber (5x) communicated with the interdental chamber (5) whose volume (V) decreases with the rotation of the outer rotor (3) and no longer communicates with the discharge port (8), While the volume (V) of the interdental chamber (5x) is decreasing, the suction The volume of the interdental chamber (5x) communicated with the port (6) and no longer communicated with the discharge port (8) is such that at least a part of the interdental chamber (5x) communicated with the suction port (6). It is characterized by increasing after.

  In this gear pump, the interdental chamber that has stopped communicating with the discharge port communicates with the suction port while the volume of the interdental chamber decreases with the rotation of the inner rotor and the outer rotor. As a result, the volume of the interdental chamber that is no longer in communication with the discharge port decreases with the rotation of the inner rotor or the like, so that fluid is discharged from the interdental chamber to the suction port. The volume of the interdental chamber that is no longer in communication with the discharge port increases after the interdental chamber communicates with the suction port. That is, the volume of the interdental chamber that is no longer in communication with the discharge port is minimized after the interdental chamber communicates with the suction port. As a result, the fluid flowing into the suction port from the interdental chamber that is no longer in communication with the discharge port causes fluid to flow into the interdental chamber from the gap between the inner rotor and the outer rotor and the member that accommodates both (axial gap). Inflow at high speed can be well controlled. Therefore, in this gear pump, it is possible to satisfactorily suppress the occurrence of cavitation in the interdental chamber that does not communicate with the discharge port and communicates with the suction port.

  In addition, the volume (V) of the interdental chamber (5x) that has stopped communicating with the discharge port (6) starts to increase after the entire interdental chamber (5x) communicates with the suction port (6). Also good. As a result, the communication area between the interdental chamber and the suction port when the fluid begins to flow from the suction port in response to an increase in volume with respect to the interdental chamber that is no longer in communication with the discharge port is suppressed. can do. As a result, an increase in the flow rate of the fluid flowing from the suction port into the interdental chamber can be suppressed, and the occurrence of cavitation associated with the suction of the fluid into the interdental chamber can be satisfactorily suppressed.

  Further, the inner rotor (2) has a tooth bottom portion (22) defining the interdental chamber (5x) that is no longer in communication with the discharge port (8), and the volume (V) of the interdental chamber (5x) ), When viewed from the axial direction of the inner rotor (2), it does not protrude from the inner peripheral edge (6ie) of the suction port (6) to the rotation center (2c) side of the inner rotor (2). You may form so that it may adjoin to this inner periphery (6ie). As a result, the minimum volume of the interdental chamber, that is, the interdental chamber and the suction port when fluid starts to flow from the suction port in response to the increase in volume with respect to the interdental chamber that is no longer communicated with the discharge port. The communication area can be increased. As a result, an increase in the flow velocity of the fluid flowing from the suction port into the interdental chamber can be suppressed, and the occurrence of cavitation accompanying the suction of the fluid into the interdental chamber can be suppressed extremely well. In this case, for example, by deepening the bottom of the outer teeth of the inner rotor (offset toward the rotation center side of the inner rotor), the bottom of the teeth is placed inside the suction port when the interdental chamber volume reaches a minimum value. The minimum volume (communication area) of the interdental chamber that is brought close to the periphery and no longer communicates with the discharge port can be increased more appropriately.

  Further, in the inner rotor (2), the interdental chamber (5x) in which the volume (V) decreases, the external teeth (20) and the internal teeth (30) that define the interdental chamber (5x). (E) is formed so as to communicate with the suction port (6) after overlapping the peripheral edge (8e) of the discharge port (8) when viewed from the (2) axial direction of the inner rotor. May be. As a result, the interdental chamber whose volume decreases with the rotation of the inner rotor or the like is communicated with the suction port almost simultaneously with the discharge port, and the fluid in the interdental chamber flows out to the suction port. Can do. Therefore, it is possible to very well regulate the flow of fluid from the gap between the inner rotor and the outer rotor and the member that accommodates both into the interdental chamber that is no longer in communication with the discharge port.

  In the inner rotor (2), the interdental chamber (5x) in which the volume (V) decreases is defined by the external teeth (20) and the internal teeth (30) that define the interdental chamber (5x). (E) is formed so as to communicate with the suction port (6) before overlapping the peripheral edge (8e) of the discharge port (8) when viewed from the (2) axial direction of the inner rotor. Also good. As a result, the interdental chamber whose volume decreases with the rotation of the inner rotor or the like is communicated with the suction port before it is not communicated with the discharge port, and an appropriate amount of fluid in the interdental chamber is transferred to the discharge port and the suction port. Can be drained. As a result, the pressure of the fluid in the interdental chamber can be held so as not to increase more than necessary, and the occurrence of vibration due to the increase in the pressure of the fluid in the interdental chamber can be suppressed.

  Further, each of the external teeth (20) of the inner rotor (2) causes the outer circle (Co) having a radius (re) smaller than the radius (rde) of the drawing point to circumscribe the basic circle (BCt). However, the tooth tip part (21) formed by the epitrochoid curve obtained by rolling without slipping may be included. That is, by keeping the radius of the abduction circle (the radius of the base circle / the number of teeth) small while increasing the drawing point radius of the epitrochoid curve, the outer diameter of the basic circle, that is, the outer diameter of the inner rotor is kept small. It is possible to easily increase the height of the external teeth. Then, by increasing the height of the external teeth, the meshing portion of the external teeth and the internal teeth (the locus of the meshing portion) with respect to the straight line passing through the rotation center of the inner rotor and the rotation center of the outer rotor is changed to the inner rotor. Or the like in the rotational direction. As a result, the rear end of the suction port in the rotation direction is brought closer to the front end of the discharge port in the rotation direction, such as the inner rotor, and the interdental chamber that is no longer in communication with the discharge port is being reduced in volume. It is possible to easily communicate with the suction port.

  Further, each of the outer teeth (20) of the inner rotor (2) is formed by an arbitrary curve, and the inner rotor (2) more than the tooth tip portion (21) and the tooth tip portion (21). ) In the rotation direction of the tooth bottom portion (22) located on the front side, and is formed by an arbitrary curve, and the tooth tip portion (21) and the tooth tip portion A second intermediate portion (24) positioned between the tooth bottom portion (22) positioned on the rear side in the rotational direction of the inner rotor (2) relative to (21), and the first intermediate portion ( The length of the curve forming 23) may be longer than the length of the curve forming the second intermediate part (24).

  Thus, by making the length of the curve forming the first intermediate portion longer than the length of the curve forming the second intermediate portion and making the external teeth asymmetrical, the epitrochoid curve forming the tooth tip portion The rear end portion in the rotation direction can be brought closer to the tooth bottom portion, and the front end portion in the rotation direction of the epitrochoid curve can be brought closer to the outer side in the radial direction of the inner rotor. Then, by bringing the end of the epitrochoid curve forming the tooth tip portion on the rear side in the rotational direction closer to the tooth bottom portion, the minimum clearance between the external teeth and the internal teeth defining the interdental space communicating with the discharge port The value can be reduced as a whole. In addition, by bringing the end portion of the epitrochoid curve forming the tooth tip portion on the front side in the rotational direction toward the outside in the radial direction of the inner rotor, the outer teeth and the inner teeth that define the interdental chamber communicating with the suction port The minimum clearance can be increased overall.

  Furthermore, the first intermediate portion (23) may be formed by at least an involute curve. As a result, the external teeth and the internal teeth can be meshed more smoothly, and the rotational speed ratio between the inner rotor and the outer rotor can be made constant.

  The discharge port is separated from the first discharge port (7) by a first discharge port (7) and a partition wall (9), and the inner rotor (2) is separated from the first discharge port (7). And a second discharge port (8) arranged on the front side in the rotation direction.

  And the invention of this indication is not limited to the above-mentioned embodiment at all, and it cannot be overemphasized that various changes can be made within the range of the extension of this indication. Furthermore, the mode for carrying out the invention described above is merely a specific embodiment of the invention described in the column for solving the problem, and is described in the column for means for solving the problem. It is not intended to limit the elements of the invention.

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

  1 Gear pump, 2Z Inner rotor, 2c, 3c Center of rotation, 3 Outer rotor, 4 Rotating shaft, 5, 5x Interdental chamber, 6 Suction port, 6e Periphery, 6ie Inner peripheral edge, 7 First discharge port, 8 Second Discharge port, 8e peripheral edge, 9 septum, 20 external teeth, 21 tooth tip, 21f, 21r, 23f, 24r end, 21t top, 22, 22z tooth bottom, 22x, 24x intersection, 22y boundary, 23 1st Intermediate part, 24 second intermediate part, 24i inner intermediate part, 24o outer intermediate part, 30 internal teeth.

Claims (12)

An intake rotor, a discharge port, an inner rotor having a plurality of external teeth, and an outer rotor having a plurality of internal teeth larger than the external teeth of the inner rotor and arranged to be eccentric with respect to the inner rotor And a plurality of interdental chambers defined by the plurality of external teeth and the plurality of internal teeth,
The discharge port communicates with the interdental chamber that decreases in volume as the inner rotor and the outer rotor rotate, and the interdental chamber that is no longer communicated with the discharge port has a volume of the interdental chamber. A gear pump characterized in that the volume of the interdental chamber communicated with the suction port during the decrease and no longer communicated with the discharge port increases after at least a part of the interdental chamber communicated with the suction port. . The gear pump according to claim 1, wherein
The volume of the interdental chamber that is no longer in communication with the discharge port starts to increase after the entire interdental chamber communicates with the suction port. The gear pump according to claim 1 or 2,
The inner rotor has the suction port as viewed from the axial direction of the inner rotor when the tooth bottom portion defining the interdental chamber that is no longer in communication with the discharge port has a minimum volume of the interdental chamber. A gear pump characterized in that the gear pump is formed so as not to protrude from the inner peripheral edge of the inner rotor to the rotation center side of the inner rotor and to be close to the inner peripheral edge. The gear pump according to any one of claims 1 to 3,
The inner rotor has an interdental chamber in which the volume decreases, and an engagement portion between the outer teeth and the inner teeth that defines the interdental chamber is seen from the axial direction of the inner rotor at the periphery of the discharge port. The gear pump is formed so as to communicate with the suction port after being overlapped. An intake rotor, a discharge port, an inner rotor having a plurality of external teeth, and an outer rotor having a plurality of internal teeth larger than the external teeth of the inner rotor and arranged eccentric to the inner rotor And a plurality of interdental chambers defined by the plurality of external teeth and the plurality of internal teeth,
The discharge port communicates with the interdental chamber whose volume decreases as the inner rotor and the outer rotor rotate, and the interdental chamber whose volume decreases decreases while the discharge port communicates with the discharge port. The gear pump, wherein the volume of the interdental chamber communicates with the suction port and increases after at least a part of the interdental chamber communicates with the suction port. The gear pump according to claim 5,
The gear pump characterized in that the volume of the interdental chamber communicated with the suction port while communicating with the discharge port starts to increase after the entire interdental chamber communicates with the suction port. The gear pump according to claim 5 or 6,
The inner rotor has the suction port as viewed from the axial direction of the inner rotor when the tooth bottom portion defining the interdental chamber that is no longer in communication with the discharge port has a minimum volume of the interdental chamber. A gear pump characterized in that the gear pump is formed so as not to protrude from the inner peripheral edge of the inner rotor to the rotation center side of the inner rotor and to be close to the inner peripheral edge. The gear pump according to any one of claims 5 to 7,
The inner rotor has an interdental chamber in which the volume decreases, and an engagement portion between the outer teeth and the inner teeth that define the interdental chamber is seen from the axial direction of the inner rotor at the periphery of the discharge port. A gear pump, wherein the gear pump is formed to communicate with the suction port before overlapping. The gear pump according to any one of claims 1 to 8 ,
Each of the outer teeth of the inner rotor has a tooth tip formed by an epitrochoid curve obtained by rolling an outer rotation circle having a radius smaller than the radius of the drawing point without slipping while circumscribing the base circle. A gear pump characterized by including. The gear pump according to claim 9 ,
Each of the outer teeth of the inner rotor is
A first intermediate portion that is formed by an arbitrary curve and is located between the tooth tip portion and a tooth bottom portion that is located on the front side in the rotation direction of the inner rotor from the tooth tip portion;
A second intermediate portion that is formed by an arbitrary curve and is located between the tooth tip portion and a tooth bottom portion that is located on the rear side in the rotation direction of the inner rotor from the tooth tip portion;
The length of the curve which forms the said 1st intermediate part is longer than the length of the curve which forms the said 2nd intermediate part, The gear pump characterized by the above-mentioned. The gear pump according to claim 10 ,
The gear pump according to claim 1, wherein the first intermediate portion is formed by at least an involute curve. The gear pump according to any one of claims 1 to 11 ,
The discharge port includes a first discharge port and a second discharge port that is partitioned from the first discharge port by a partition wall and is disposed on the front side in the rotation direction of the inner rotor with respect to the first discharge port. A gear pump characterized by that.