JP6498435B2 - Gear pump - Google Patents

Description

  The present invention relates to a gear pump, and more particularly to an external gear pump in which main parts such as a gear member (hereinafter also referred to as “pump gear”) for pumping fluid are made of resin.

  Gear pumps are relatively simple among positive displacement pumps, have a small number of parts, and are high in mechanical efficiency, making them suitable for miniaturization. In addition, the main parts made of resin are excellent in cost and productivity. Yes. Because of these advantages, resin gear pumps are widely used as fluid transfer means in household appliances such as automatic ice making devices for refrigerators and hot water washing toilet seats.

  Patent Document 1 below discloses a gear pump (1) having a drive gear (7) provided with a shaft hole (7a) corresponding to the shape of the D-cut portion (5a) of the support shaft (5). Patent Document 2 below discloses a gear pump that suppresses sink marks during injection molding by forming the pump gears (1, 4) with a liquid crystal polymer.

JP 2013-076347 A JP 2000-303967 A

  On the other hand, the gear pump has a significant effect on the volumetric efficiency due to the viscosity of the fluid to be transferred. For the purpose of transferring a low-viscosity fluid such as water, it is possible to transfer air so that no priming water is required at the start. In order to achieve this, dimensional accuracy on the order of microns is required.

  When a resin pump gear is manufactured by injection molding, distortion caused by sink marks created during the manufacturing process creates unnecessary gaps between the outer peripheral surface and both end surfaces of the pump gear and the inner wall surface of the pump chamber. May decrease. In order to prevent the occurrence of such sink marks, the pump gear is generally thinned. When molding pump gears without solidening, measures such as using resin materials that do not easily cause sink marks or using a molding machine with a special control mechanism to prevent sink marks are required. It is.

  In the pump gear, a weld line is formed at a location where the melt front of the resin injected from the gate at the time of manufacture joins in the mold. The portion where the weld line is formed becomes weaker in strength than the non-weld portion.

  In addition, among the pump gears, the drive gears that are rotationally driven by the motor directly or via other gears are subjected to D-cut processing on the shaft hole and the support shaft of the drive gear in order to transmit the driving force of the motor without loss. In this case, the stress at the time of rotation is concentrated on the circumferential end of the D-cut surface of the drive gear. When the stress concentration part of the D-cut part overlaps the weld line of the pump gear that has been hollowed out, such a part becomes a bottleneck in the strength of the entire gear, which may easily cause cracks.

  In view of the above problems, the problem to be solved by the present invention is that it can be manufactured with high dimensional accuracy without using a special resin material or injection molding machine that suppresses the occurrence of sink marks, and on the strength based on the weld line. It is an object of the present invention to provide a gear pump having a drive gear with reduced vulnerability.

In order to solve the above problems, a gear pump according to the present invention includes a housing having a fluid suction port and a discharge port, a pump chamber communicating the suction port and the discharge port, and a motor accommodated in the housing. And a pump gear that is a pair of resin-made gears that are disposed in the pump chamber and that pumps the fluid, and the pump gear is driven directly by the motor or via another gear. The drive gear includes a drive gear that is rotationally driven and a driven gear that meshes with the drive gear. The drive gear has a weld line that extends linearly in a radial direction, and the shaft hole portion of the drive gear has an inner peripheral surface. A D-cut portion provided with a flat D-cut surface in a part of the circumferential direction at a half line passing through the circumferential end of the D-cut surface starting from the radial center of the D-cut portion; ,Previous And weld line is then different from the circumferential position in said driving gear, lightening portion is recessed in between the shaft hole and the teeth in the end face of the drive gear, the lightening portion Is provided with a rib integrally formed with the drive gear, and the rib extends linearly outward from the shaft hole portion, and the rib and the weld line have the same circumferential position in the drive gear. The shaft hole portion has the D-cut portion at one end portion in the axial direction and the cylindrical portion having a circular radial cross section at the other portion, and the cylindrical portion includes the drive gear. A cylindrical part having a circular radial cross section in the support shaft is inserted, the thinned part and the rib are provided on both end faces of the drive gear, and the rib provided on the end face on the cylindrical part side of the drive gear is: Provided on the end face on the D cut part side And summarized in that a compact than blanking.

By keeping the position of the end of the D-cut surface and the position of the weld line away from each other in the circumferential direction of the D-cut portion, it is possible to avoid overlapping the portion where the tensile strength of the drive gear is low and the portion where stress is concentrated during power transmission. Therefore, it is possible to prevent fragile portions on strength from being concentrated on the D-cut portion. Further, even when the thinning is performed in order to prevent the sink at the time of injection molding of the drive gear, it is possible to secure a wide contact area of the weld surface by providing the rib on the weld line of the thinned portion. Thereby, the fall of the tensile strength in a weld line is suppressed, and coexistence with the dimensional accuracy and intensity | strength of a drive gear can be aimed at. Then, the D-cut portion of the drive gear and the D-cut portion of the support shaft are engaged, so that the support shaft is prevented from idling and the driving force of the motor is transmitted to the drive gear without loss. Furthermore, the positioning accuracy of the radial position of the drive gear is ensured by inserting the cylindrical portion into the cylindrical portion of the support shaft. In the drive gear, it is mainly the end face on the side having the D-cut portion that requires strength reinforcement. Since there is no portion where stress is concentrated on the end face on the cylindrical portion side as on the D cut portion side, there is no problem even if the rib is not provided. Rather, it can be said that it is more cost-effective to not provide ribs. However, when the rib is provided only on the D-cut portion side, there is a concern that the shake at the time of rotation increases due to the deviation of the center of gravity of the drive gear. Therefore, by providing a rib having a smaller diameter than the D-cut portion on the cylindrical portion side, it is possible to achieve both the cost of the drive gear and the rotational stability.

In order to solve the above problems, a gear pump of the present invention is accommodated in a housing having a fluid suction port and a discharge port, and a pump chamber communicating the suction port and the discharge port. An external gear pump including a motor and a pump gear that is a pair of gears made of resin that is disposed in the pump chamber and pumps the fluid, wherein the pump gear is directly or otherwise driven by the motor. And a driven gear meshing with the drive gear. The drive gear has a weld line extending linearly in the radial direction. A D-cut portion provided with a flat D-cut surface in a part of the circumferential direction on the peripheral surface, and a half passing through the circumferential end of the D-cut surface with the radial center of the D-cut portion as a starting point Straight line and The weld line has a different circumferential position in the drive gear, and a hollow portion is provided between the shaft hole portion and the tooth portion on the end surface of the drive gear, Is provided with a rib integrally formed with the drive gear, and the rib extends linearly outward from the shaft hole portion, and the rib and the weld line have the same circumferential position in the drive gear. In addition, the gist is that a gap is provided between a side surface on the tooth portion side of the lightening portion and a facing surface of the rib facing the side surface.

By keeping the position of the end of the D-cut surface and the position of the weld line away from each other in the circumferential direction of the D-cut portion, it is possible to avoid overlapping the portion where the tensile strength of the drive gear is low and the portion where stress is concentrated during power transmission. Therefore, it is possible to prevent fragile portions on strength from being concentrated on the D-cut portion. Further, even when the thinning is performed in order to prevent the sink at the time of injection molding of the drive gear, it is possible to secure a wide contact area of the weld surface by providing the rib on the weld line of the thinned portion. Thereby, the fall of the tensile strength in a weld line is suppressed, and coexistence with the dimensional accuracy and intensity | strength of a drive gear can be aimed at. Further, by providing a lightening portion on the end face of the drive gear, it is possible to prevent sink marks during injection molding of the drive gear. On the other hand, since the strength of the drive gear becomes insufficient simply by providing the lightening portion, there is a concern that the volumetric efficiency is reduced due to the deflection of the drive gear, noise is generated, and the life of the parts is reduced. By providing ribs in the lightening part, the strength of the drive gear as a whole is maintained, and in order to prevent sink marks generated on the ribs from affecting the tooth part, the side surface on the tooth part side of the lightening part and the rib facing the side surface By providing a gap between the opposing surfaces, it is possible to achieve both strength and dimensional accuracy of the drive gear.

Further, the thinned portion is provided concentrically on the end face or both end faces of the drive gear, and the drive gear includes a plurality of the weld lines and the ribs at equal intervals in the circumferential direction, and one of the weld lines. May extend from the D-cut surface in a direction perpendicular to the D-cut surface.

Further, the shaft hole portion has the D-cut portion at one end in the axial direction, and a cylindrical portion having a circular radial cross section at the other portion. The cylindrical portion includes a support shaft of the drive gear. the radial cross-section in is inserted a cylindrical portion of circular desirable.

  By engaging the D-cut portion of the drive gear with the D-cut portion of the support shaft, idling of the support shaft is prevented, and the driving force of the motor is transmitted to the drive gear without loss. Furthermore, the positioning accuracy of the radial position of the drive gear is ensured by inserting the cylindrical portion into the cylindrical portion of the support shaft.

  Further, the thinned portion and the rib are provided on both end surfaces of the drive gear, and the rib provided on the end surface on the cylindrical portion side of the shaft hole portion in the drive gear is an end surface on the D cut portion side. It is good also as a structure smaller than the said rib provided in.

  In the drive gear, it is mainly the end face on the side having the D-cut portion that requires strength reinforcement. Since there is no portion where stress is concentrated on the end face on the cylindrical portion side as on the D cut portion side, there is no problem even if the rib is not provided. Rather, it can be said that it is more cost-effective to not provide ribs. However, when the rib is provided only on the D-cut portion side, there is a concern that the shake at the time of rotation increases due to the deviation of the center of gravity of the drive gear. Therefore, by providing a rib having a smaller diameter than the D-cut portion on the cylindrical portion side, it is possible to achieve both the cost of the drive gear and the rotational stability.

  The gear pump according to the present invention can be manufactured with high dimensional accuracy without using a special resin material or injection molding machine that suppresses the occurrence of sink marks, and the weakness in strength based on the weld line is reduced. A gear pump having a drive gear can be provided.

1 is an exploded perspective view of a gear pump 1. FIG. It is a front view sectional view of gear pump 1 after an assembly. It is explanatory drawing which shows the fluid transfer principle in the gear pump. It is the top view and bottom view of the pump gearwheel 20. FIG. 2 is a plan view, a perspective view, and a partially enlarged view of a drive gear 21. It is the perspective view and sectional drawing of the drive gear 21 in which the spindle 51 was penetrated.

  Hereinafter, embodiments of a gear pump according to the present invention will be described in detail with reference to the drawings. The gear pump 1 according to the present embodiment is a device that constitutes an automatic ice making device mounted on a refrigerator, and is a pump that transfers water from a water storage tank to an ice tray. In the present embodiment, “upper” and “lower” refer to the upper and lower sides shown in FIG. 1, and “horizontal direction” refers to a direction orthogonal to the upper and lower directions. "Front view" refers to the direction of the line of sight when the gear pump 1 is observed from the front with the side where the inlet 111 is provided in FIG. 1, and "plan view" refers to the gear pump 1 from above in FIG. The direction of the line of sight when observed.

(overall structure)
FIG. 1 is an exploded perspective view of the gear pump 1, and FIG. 2 is a front sectional view of the gear pump 1 after assembly (a sectional view taken along the line AA in FIG. 1). As shown in FIG. 1 and FIG. 2, the gear pump 1 of this embodiment mainly includes a housing 10, a motor 40 accommodated in the housing 10, and a pair of large and small screws that transmit the driving force of the motor 40 at a reduced speed. It is comprised by the reduction gear train 30 which consists of a gear, and the pump gear 20 which is a pair of spur gear which pumps the water which is the transfer fluid of the gear pump 1. As shown in FIG.

  The housing 10 is divided into four parts in the vertical direction, and has a first housing body 11, a second housing body 12, a third housing body 13, and a fourth housing body 14 in order from the top. Screw holes are provided in the upper and lower directions at the same positions of the four corners in plan view of the housing bodies, and the first to fourth housing bodies are integrated as a housing 10 by screwing screws 101 into the screw holes. It becomes.

  The first housing body 11 includes a suction port 111 and a discharge port 112 for water that is a transfer fluid. The suction port 111 takes water from a water storage tank (not shown) into a pump chamber 50 to be described later through a pipe, and the discharge port 112 supplies water taken into the pump chamber 50 to an ice tray (not shown) via a pipe. To do.

  As shown in FIG. 2, the inner wall surface of the first housing body 11 and the upper surface of the second housing body 12 define a pump chamber 50 in which the pump gear 20 is disposed. An O-ring 53 is attached to a contact portion between the first housing body 11 and the second housing body 12, and leakage of water from the pump chamber 50 to the outside of the housing 10 is prevented. The O-ring 53 is compressed in the horizontal direction by the inner wall surface of the lower end portion of the first housing body 11 and the side surface of the second housing body 12 facing the inner wall surface. Since the O-ring 53 is compressed in the horizontal direction, the first housing body 11 is prevented from being lifted upward by the repulsive force of the O-ring 53 even when the screw 101 is loosened, and the pump chamber 50 sealability is maintained.

  Support shafts 51 and 52 that support the pump gear 20 are erected in the pump chamber 50, and the support shaft 51 penetrates the second housing body 12 in the vertical direction. On the lower surface of the second housing body 12 at the position where the through hole of the support shaft 51 is provided, a seal member 54 that is a disk-like elastic member that stops the progress of water leaking from the through hole is disposed. .

  The pump gear 20 is fixed to the support shaft 51 and rotated together with the support shaft 51, and is rotatably supported by the support shaft 52. The pump gear 20 meshes with the drive gear 21 and rotates in conjunction with the rotation of the drive gear 21. Driven gear 22. Both the drive gear 21 and the driven gear 22 are resin gears manufactured by injection molding.

  The lower surface of the second housing body 12 and the inner wall surface of the third housing body 13 define a gear chamber 60 in which the reduction gear train 30 is disposed. A support shaft 51 penetrates into the gear chamber 60 from the second housing body 12 side, and a rotation shaft 41 of the motor 40 penetrates from the bottom of the third housing body 13. A first helical gear 31, which is a large-diameter helical gear constituting the reduction gear train 30, is fixed to the support shaft 51, and the support shaft 51 rotates with the rotation of the helical gear 31. The second helical gear 32 that is a small-diameter helical gear is fixed to the rotating shaft 41 as a pinion gear, and rotates together with the rotating shaft 41 by the driving force of the motor 40.

  The fourth housing body 14 has a cylindrical space portion extending in the up-down direction with an upper end opened, and a motor 40 is accommodated in the space portion. The motor 40 is a known brushless DC motor. Details of the internal mechanism of the motor 40 are omitted.

(Pump chamber structure)
FIG. 3 is an explanatory view showing the principle of fluid transfer in the gear pump 1. When the pump gear 20 disposed in the pump chamber 50 rotates and the teeth of the meshing portion of the pump gear 20 are separated from each other, a negative pressure is generated on the suction port 111 side of the pump chamber 50, and fluid is sucked by the negative pressure. The air is sucked into the pump chamber 50 from the port 111. The sucked fluid is enclosed in a space defined by the inner wall surface of the pump chamber 50 and the tooth portion of the pump gear 20, and is conveyed to the discharge port 112 side of the pump chamber 50. The fluid conveyed to the discharge port 112 side is pumped out of the pump chamber 50 from the discharge port 112 by the positive pressure generated when the teeth of the pump gear 20 mesh.

  The gear pump 1 in this embodiment is intended for transferring water, which is a low-viscosity fluid, and also enables the transfer of air, which is a compressible fluid, so that no priming water is required at the time of starting. is there. Therefore, high dimensional accuracy is required for the positions of the outer peripheral surface and both end surfaces of the pump gear 20 and the position of the inner wall surface of the pump chamber 50.

(Pump gear shape)
FIG. 4 is a plan view (FIG. 4A) and a bottom view (FIG. 4B) of the pump gear 20. Hereinafter, the shape of the pump gear 20 will be described using the drive gear 21 as an example. The drive gear 21 in the present embodiment is a resin gear manufactured by injection molding, and in order to prevent dimensional accuracy from being lowered due to sink marks generated during injection molding, shaft hole portions 211 on both end surfaces of the drive gear 21 and A hollow portion 213 is concentrically recessed between the tooth portions 212. The shaft hole portion 211 here includes not only the shaft hole through which the support shaft 51 is inserted, but also a cylindrical body portion that is continuous in the circumferential direction near the shaft hole that defines the shaft hole.

  By simply providing the lightening portion 213, the strength of the drive gear 21 becomes insufficient, and there is a concern that the volumetric efficiency will be reduced due to the deflection of the drive gear 21, the generation of noise, and the life of parts will be reduced. Therefore, in order to maintain the strength of the drive gear 21, a rib 214 integrally formed with the drive gear 21 is provided in the lightening portion 213. The ribs 214 extend linearly from the shaft hole portion 211 toward the outer side in the radial direction, and three ribs 214 are provided at equal intervals in the circumferential direction. The strength of the drive gear 21 is maintained by the ribs 214. In addition, the lightening part 213 here refers to the part between the shaft hole part 211 and the tooth | gear part 212 in the perimeter of the drive gear 21, including the circumferential direction range in which the rib 214 was formed.

  As described above, the drive gear 21 is a resin gear manufactured by injection molding. Point B shown in FIG. 4A is a gate mark in which resin is injected into the mold when the drive gear 21 is manufactured. The drive gear 21 is manufactured by injecting resin from three gates arranged at equal intervals in the circumferential direction and at equal radial distances from the center. A dotted line C shown in FIG. 4A is a weld line where the melt front of the resin injected from the gate joins in the mold. In general, the weld line is weaker in strength than the non-weld portion.

  The drive gear 21 in the present embodiment is provided with a linear rib 214 along a position where such a weld line is formed. Since the weld line and the circumferential position of the rib 214 overlap, the adhesion area of the weld surface is secured wider than the other lightening portions 213, and the tensile strength in the weld line is increased. Thereby, the weakness in the strength surface of the drive gear 21 whole is reduced.

  In order to reduce the weakness of strength due to the weld line, it is desirable to provide the ribs 214 along the positions where all the weld lines are formed. Since the drive gear 21 in the present embodiment is manufactured by injecting resin from three gates, there are three weld lines in the molded product. Due to this structure, the drive gear 21 is provided with three ribs 214. However, the above is a desirable configuration, and the number of ribs 214 is not necessarily the same as the number of weld lines, and does not have to be provided along the position where the weld lines are formed. The number and position of the ribs 214 can be appropriately adjusted according to the number of weld lines formed in the drive gear 21 and the strength required for the drive gear 21.

  5A is a plan view of the drive gear 21, FIG. 5B is a perspective view of the drive gear 21, and FIG. 5C is an enlarged view of a portion surrounded by a broken line in FIG. 5A. As shown in FIG. 5, a gap 215 is provided between the side surface on the tooth portion 212 side of the lightening portion 213 of the drive gear 21 and the facing surface of the rib 214 facing the side surface. The reason why the facing surface of the rib 214 is inclined is simply to provide a draft angle during injection molding.

  While the drive gear 21 is required to have high dimensional accuracy, the rib 214 needs to have a thickness and a width so that the strength of the drive gear 21 can be maintained. The sinking of the rib 214 affects the dimensional accuracy. There is concern. In the drive gear 21 according to the present embodiment, the gap 214 is provided between the rib 214 and the side surface on the tooth portion 212 side of the lightening portion 213, so that the rib 214 has a sink when the drive gear 21 is manufactured. Even in such a case, the influence does not reach the tooth portion 212. As a result, both the strength and dimensional accuracy of the drive gear 21 are achieved.

  The drive gear 21 of the present embodiment secures the strength by the linear ribs 214 having a necessary and sufficient width in consideration of material efficiency, but the ribs 214 are not necessarily linear. For example, even in a configuration in which the rib 214 is formed over the entire circumference, it is possible to achieve both strength and dimensional accuracy if the gap 215 is provided.

  The characteristics related to the shape of the drive gear 21 described so far are the same in the driven gear 22. However, the drive gear 21 and the driven gear 22 are different in the shape of the shaft holes of the shaft hole portions 211 and 221.

  As described above, the drive gear 21 rotates with the support shaft 51, and the driven gear 22 is rotatably supported by the support shaft 52 and rotates in conjunction with the rotation of the drive gear 21. 6A is a perspective view of the drive gear 21 through which the support shaft 51 is inserted, and FIG. 6B is a cross-sectional view taken along line EE of FIG. 6A. As shown in FIG. 6, a D-cut portion 511 in which a part of the outer peripheral surface is cut out in a planar shape is formed on the upper portion of the support shaft 51, and the shaft hole of the drive gear 21 through which the support shaft 51 is inserted. A D-cut portion 211 a having a shape complementary to the D-cut portion 511 is also formed on the upper portion of the portion 211. By engaging the D-cut portion 511 of the support shaft 51 with the D-cut portion 211a of the drive gear 21, the drive gear 21 is positioned in the circumferential direction on the support shaft 51 and the idling of the drive gear 21 is prevented. .

  A portion below the D-cut portion 511 in the support shaft 51 is a cylindrical portion 512 having a circular radial section, and a portion corresponding to the cylindrical portion 512 of the shaft hole portion 211 of the drive gear 21 is also circular in the radial direction. This is a cylindrical portion 211b. The cylindrical portion 211b is press-fitted into the column portion 512, whereby the radial position of the drive gear 21 is positioned.

  Power is transmitted from the support shaft 51 to the driving gear 21 at the circumferential end of the flat D-cut surface 211c provided in the D-cut portion 211a (hereinafter, also simply referred to as “the corner of the D-cut portion 211a”). Sometimes stress is concentrated. As shown in FIG. 4A, three weld lines of the drive gear 21 are formed at equal intervals in the circumferential direction, one of which is perpendicular to the D-cut surface 211c from the D-cut surface 211c. It extends. Accordingly, the half line D passing through the corner of the D-cut portion 211a starting from the radial center of the D-cut portion 211a and the three weld lines are provided at the farthest position in the circumferential direction of the drive gear 21. Become. By separating the corner of the D-cut portion 211a and the position of the weld line, it is possible to avoid a portion where the tensile strength of the drive gear 21 is low and a portion where stress is concentrated during rotation from overlapping, and the D-cut portion 211a Concentration of weak points on strength at corners is avoided.

  The shaft hole portion 221 and the support shaft 52 of the driven gear 22 do not have a configuration corresponding to the D-cut portion, and both the shaft hole portion 221 and the support shaft 52 have a circular radial cross section in the entire vertical length.

  Further, as shown in FIG. 4, in the present embodiment, the lightening portions 213 and the ribs 214 are provided on both end surfaces of the drive gear 21. The drive gear 21 needs to be strengthened mainly on the end face on the side having the D-cut portion 211a, but by providing a smaller rib 214 on the cylindrical portion 211b side than the D-cut portion 211a side, Both cost and rotational stability are achieved.

(Gear pump operation)
Hereinafter, operation | movement of the gear pump 1 concerning this embodiment is demonstrated using FIG.

  When DC power is supplied to the terminal 42 of the motor 40 and the rotating shaft 41 rotates, the second helical gear 32 fixed to the upper portion of the rotating shaft 41 rotates together with the rotating shaft 41. The second helical gear 32 meshes with the first helical gear 31 having a larger diameter than the second helical gear 32, and the rotation of the second helical gear 32 is the first helical gear 32. One helical gear 31 decelerates and is transmitted to the support shaft 51.

  A helical gear is used for the reduction gear train 30 that transmits the driving force of the motor 40 to the pump gear 20, so that the collision noise of the teeth at the meshing portion of the reduction gear train 30 is alleviated, and the gear pump 1 is operated. Noise at the time has been reduced. Further, since thrust in the thrust direction is also generated on the support shaft 51, the support shaft 51 is pressed in any one of the axial directions to prevent backlash, and the drive gear 21 fixed to the support shaft 51 rotates. Is expected to stabilize.

  When the driving force of the motor 40 is transmitted to the support shaft 51, the drive gear 21 fixed to the support shaft 51 penetrating into the pump chamber 50 rotates in the direction shown in FIG. The D-cut portion 211 a of the drive gear 21 is engaged with the D-cut portion 511 of the support shaft 51, so that the support shaft 51 is prevented from idling, and the cylindrical portion 211 b of the drive gear 21 is connected to the column portion 512 of the support shaft 51. By being inserted, the positioning accuracy of the radial position of the drive gear 21 is ensured. In the present embodiment, the driving force of the motor 40 is transmitted to the driving gear 21 via the reduction gear train 30, but this is not an essential configuration, and the driving gear 21 is attached to the rotating shaft 41 of the motor 40. A direct fixing configuration is also conceivable.

  As shown in FIG. 4, the weld line of the drive gear 21 is formed at a position away from the corner of the D-cut portion 211a where stress is concentrated. In addition, ribs 214 are provided on each weld line to ensure a wide contact area of the weld surface. With this configuration, the weakness in the strength of the drive gear 21 due to the weld line is reduced.

  As shown in FIG. 3, when the drive gear 21 rotates, the driven gear 22 that meshes with the drive gear 21 also rotates in conjunction with it. When the drive gear 21 and the driven gear 22 rotate and the teeth of the meshing portion are separated, a negative pressure is generated on the suction port 111 side of the pump chamber 50. When negative pressure is generated on the suction port 111 side, water is sucked into the pump chamber 50 from the suction port 111. The sucked water is enclosed in a space defined by the inner wall surface of the pump chamber 50 and the tooth portion of the pump gear 20, and is transported to the discharge port 112 side as the pump gear 20 rotates. The water transported to the discharge port 112 side is pumped out of the pump chamber 50 from the discharge port 112 by the positive pressure generated when the teeth of the pump gear 20 mesh.

  Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the gist of the present invention.

1 Gear pump 1
10 Housing 10
111 Suction port 112 Discharge port 20 Pump gear 21 Drive gear 211 Shaft hole portion 211a D cut portion 211b Cylindrical portion 211c D cut surface 212 Tooth portion 213 Thickening portion 214 Rib 215 Gap 22 Drive gear 50 Pump chamber 51 Support shaft 511 D cut Part 512 cylindrical part 52 spindle

Claims (5)

A housing having a fluid suction port and a discharge port, and a pump chamber communicating the suction port and the discharge port;
A motor housed in the housing;
A circumscribed gear pump comprising a pump gear that is a pair of resin gears that are disposed in the pump chamber and pumps the fluid;
The pump gear includes a drive gear that is driven to rotate by the motor directly or via another gear, and a driven gear that meshes with the drive gear,
The drive gear has a weld line extending linearly in the radial direction,
The shaft hole portion of the drive gear has a D-cut portion provided with a flat D-cut surface on a part of the inner circumferential surface in the circumferential direction,
The semi-straight line starting from the radial center of the D-cut portion and passing through the circumferential end of the D-cut surface, and the weld line have different circumferential positions in the drive gear ,
Between the shaft hole portion and the tooth portion on the end face of the drive gear, a lightening portion is recessed,
A rib integrally formed with the drive gear is provided in the lightening portion,
The rib linearly extends radially outward from the shaft hole,
The rib and the weld line have the same circumferential position in the drive gear,
The shaft hole portion has the D-cut portion at one end in the axial direction, and a cylindrical portion having a circular radial cross section at the other portion,
In the cylindrical part, a cylindrical part having a circular radial cross section in the support shaft of the drive gear is inserted,
The lightening part and the rib are provided on both end faces of the drive gear,
2. The gear pump according to claim 1, wherein the rib provided on the end face on the cylindrical portion side of the drive gear is smaller than the rib provided on the end face on the D cut portion side . A housing having a fluid suction port and a discharge port, and a pump chamber communicating the suction port and the discharge port;
A motor housed in the housing;
A circumscribed gear pump comprising a pump gear that is a pair of resin gears that are disposed in the pump chamber and pumps the fluid;
The pump gear includes a drive gear that is driven to rotate by the motor directly or via another gear, and a driven gear that meshes with the drive gear,
The drive gear has a weld line extending linearly in the radial direction,
The shaft hole portion of the drive gear has a D-cut portion provided with a flat D-cut surface on a part of the inner circumferential surface in the circumferential direction,
The semi-straight line starting from the radial center of the D-cut portion and passing through the circumferential end of the D-cut surface, and the weld line have different circumferential positions in the drive gear,
Between the shaft hole portion and the tooth portion on the end face of the drive gear, a lightening portion is recessed,
A rib integrally formed with the drive gear is provided in the lightening portion,
The rib linearly extends radially outward from the shaft hole,
The rib and the weld line have the same circumferential position in the drive gear,
A gear pump, wherein a gap is provided between a side surface of the lightening portion on the tooth portion side and an opposing surface of the rib facing the side surface. The hollow portion is provided concentrically on the end face or both end faces of the drive gear ,
The drive gear has a plurality of weld lines and ribs at equal intervals in the circumferential direction,
3. The gear pump according to claim 1 , wherein one of the weld lines extends in a direction perpendicular to the D-cut surface from the D-cut surface. 4. The shaft hole portion has the D-cut portion at one end in the axial direction, and a cylindrical portion having a circular radial cross section at the other portion,
Wherein the cylindrical portion, the gear pump according to claim 3 radial cross-section of the support shaft of the driving gear to quote claim 2 or claim 2, wherein the cylindrical portion of the circular are inserted. The lightening part and the rib are provided on both end faces of the drive gear,
The gear pump according to claim 4 , wherein the rib provided on the end surface on the cylindrical portion side of the drive gear is smaller than the rib provided on the end surface on the D cut portion side.

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