JP2018189018A - External gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external gear pump which can be miniaturized and can sufficiently secure a connection strength between a drive shaft and a drive gear which are rotationally driven by a drive source. A circumscribed gear pump 1 accommodates a motor shaft 81, a drive gear 2 connected to the motor shaft 81, a driven gear 3 that rotates by meshing with the drive gear 2, and a drive gear 2 and a driven gear 3. It is provided with a housing 4. The housing 4 includes a cylinder portion 41 that accommodates the drive gear 2 and the driven gear 3, first and second side plate portions 42, 43 provided on one side and the other side in the axial direction of the cylinder portion 41, and the drive gear 2. The drive gear 2 has a first support portion 44 for supporting the motor shaft 81 and a second support portion 45 for supporting the driven gear 3. The support hole 202 into which the first support portion 44 is inserted is provided, and the fitting hole 201 and the support hole 202 are formed so as to overlap each other in the axial direction of the drive gear 2. [Selection diagram] Fig. 1

Description

  The present invention relates to an external gear pump that sucks and discharges fluid by rotation of a driving gear and a driven gear that mesh with each other.

  2. Description of the Related Art Conventionally, an external gear pump that sucks and discharges fluid by rotation of a drive gear and a driven gear is used in, for example, an automatic transmission of an automobile. The driving gear and the driven gear are accommodated in a pump chamber formed in the housing, and the tooth tip faces the inner surface of the pump chamber. The driving gear is rotated by the driving force of a driving source such as an electric motor, and the driven gear is rotated by meshing with the driving gear.

  The drive gear (primary gear) and the driven gear of the external gear pump described in Patent Document 1 are coaxially extended from a gear main body provided with a plurality of external teeth, and one axial end and the other end of the gear main body. And an axial shaft. These shafts are inserted into bearings provided in the housing. The drive gear has a tip portion of one shaft protruding outside the housing, and rotates by receiving a driving force of a driving source from the protruding portion.

  The drive gear (first gear) and the driven gear (second gear) of the external gear pump described in Patent Document 2 are formed in a hollow cylindrical shape, and are provided in a housing (casing) at the center thereof. A pair of bearing journals are received respectively. A drive shaft that transmits a driving force to the drive gear is inserted into the support journal that supports the drive gear, and the drive shaft and the drive gear are connected via a molding head provided at the tip of the drive shaft. Yes.

JP 2000-130358 A Japanese Patent Laid-Open No. 10-288168

  When the external gear pump configured as described above is mounted on, for example, an automobile, it is desired to be as small as possible for the convenience of mounting. In the external gear pump described in Patent Document 2, since the drive gear and the driven gear are supported by a support journal received in the center thereof, the axial reduction in size compared to the external gear pump described in Patent Document 1 is achieved. It becomes possible. However, since the drive shaft and the drive gear are connected via a molding head in a slight gap between the tip of the support journal and the housing, it is difficult to increase the connection strength and the load capacity may be limited. There is.

  Therefore, an object of the present invention is to provide an external gear pump that can be reduced in size and can sufficiently secure the connection strength between a drive shaft that is rotationally driven by a drive source and the drive gear.

  In order to achieve the above object, the present invention provides a drive shaft that is rotated by a driving force of a drive source, a drive gear that is coupled to the drive shaft, a driven gear that is rotated by meshing with the drive gear, and the drive A housing in which a pump chamber in which a gear and the driven gear are accommodated is formed, and an external gear pump that sucks fluid from the suction side by the rotation of the drive gear and the driven gear and discharges the fluid to the discharge side, The housing is provided with a cylindrical portion having an inner surface facing the tooth tip surfaces of the gear teeth of the drive gear and the driven gear, and the pump chamber together with the cylindrical portion provided on one side and the other side of the cylindrical portion. A pair of side plate portions to be formed, a first support portion for supporting the drive gear, and a second support portion for supporting the driven gear, wherein the first support portion is the pair of side plate portions. One side plate part The drive gear has a fitting hole into which the drive shaft is fitted so as not to be relatively rotatable, and a support hole into which the first support part is inserted. A circumscribed gear pump is provided in which a joint hole and the support hole are formed so as to overlap with each other in the axial direction of the drive gear.

  According to the external gear pump according to the present invention, it is possible to reduce the size and sufficiently secure the connection strength between the drive shaft and the drive gear that are rotationally driven by the drive source.

It is sectional drawing which shows the external gear pump which concerns on the 1st Embodiment of this invention. It is a disassembled perspective view of a circumscribed gear pump. It is a perspective view which shows the motor shaft which is a drive shaft. It is the sectional view on the AA line of FIG. It is sectional drawing which shows the external gear pump which concerns on 2nd Embodiment. It is a perspective view which shows the motor shaft which concerns on 2nd Embodiment. It is sectional drawing which shows the external gear pump which concerns on 3rd Embodiment. It is a perspective view which shows the 2nd side plate part which concerns on 3rd Embodiment, and the 1st and 2nd support part.

[First Embodiment]
Embodiments of the present invention will be described with reference to FIGS. In addition, although embodiment described below is shown as a suitable specific example in implementing this invention, although there are some parts which have illustrated various technical matters that are technically preferable. The technical scope of the present invention is not limited to this specific embodiment.

  FIG. 1 is a sectional view showing an external gear pump according to a first embodiment of the present invention. FIG. 2 is an exploded perspective view showing the external gear pump. FIG. 3 is a perspective view showing a motor shaft which is a drive shaft. FIG. 4 is a cross-sectional view taken along line AA in FIG. The external gear pump 1 is mounted on, for example, an automobile and supplies hydraulic oil as a fluid to an actuator of an automatic transmission that changes the output of the engine.

(Configuration of external gear pump)
The external gear pump 1 is a housing in which a drive gear 2 that is rotationally driven in one direction, a driven gear 3 that rotates by meshing with the drive gear 2, and a pump chamber 400 in which the drive gear 2 and the driven gear 3 are accommodated. 4, first and second bearings 5 and 6 that smoothly rotate the drive gear 2 and the driven gear 3, a plate-like side plate 7 made of resin, and a motor unit 8 that rotationally drives the drive gear 2. The hydraulic fluid is sucked from the suction side and discharged to the discharge side by the rotation of the drive gear 2 and the driven gear 3.

  The motor unit 8 includes a driving force generation mechanism 80 as a driving source, a motor shaft 81 connected to the driving gear 2 and rotated by the driving force of the driving force generation mechanism 80, and first and second supporting the motor shaft 81. Rolling bearings 82 and 83, and a seal member 84 that is in sliding contact with the motor shaft 81. The driving force generation mechanism 80 includes an annular stator 85 held by the housing 4 and a rotor 86 disposed inside the stator 85, and acts between the stator 85 and the rotor 86. Driving force is generated by magnetic force.

  The stator 85 includes an iron core 851, an insulator 852 held by the iron core 851, and a winding 853 wound around the insulator 852. An excitation current is supplied to the winding 852 from a control device (not shown). The rotor 86 has a core 861 fixed to the motor shaft 81 and a plurality of permanent magnets 862 attached to the outer peripheral surface of the core 861.

  The first rolling bearing 82 supports the motor shaft 81 on the drive gear 2 side relative to the rotor 86, and the second rolling bearing 83 supports the motor shaft 81 on the opposite side of the rotor 86 from the driving gear 2. doing. The first and second rolling bearings 82 and 83 are ball bearings having outer rings 821 and 831, inner rings 822 and 832, and a plurality of spherical rolling elements 823 and 833, respectively.

  As shown in FIG. 3, the motor shaft 81 integrally includes a fitting portion 810 to be fitted to the drive gear 2 and cylindrical first to third shaft portions 811 to 813 having different outer diameters. Yes. The first to third shaft portions 811 to 813 are arranged in the axial direction, and the outer diameter of the first shaft portion 811 continuing to the fitting portion 810 is smaller than the outer diameter of the second shaft portion 812. The outer diameter of the third shaft portion 813 at the opposite end is larger than the outer diameter of the second shaft portion 812. A core 861 of the rotor 86 is fixed to the outer periphery of the second shaft portion 812. The inner ring 822 of the first rolling bearing 82 is fitted to the end of the first shaft portion 811 on the second shaft portion 812 side, and the inner ring 832 of the second rolling bearing 83 is the third shaft portion 812. It is fitted to the end on the shaft 813 side.

  The drive gear 2 integrally includes a base portion 21 at the center portion and a plurality of gear teeth 22 provided radially from the base portion 21. Further, the drive gear 2 has a fitting hole 201 into which the fitting portion 810 of the motor shaft 81 is fitted so as not to be relatively rotatable, and a support hole 202 into which a first support portion 44 of the housing 4 described later is inserted. doing. The fitting hole 201 and the support hole 202 are formed in the base portion 21 along the axial direction of the drive gear 2. In the present embodiment, the fitting hole 201 is formed in the center portion of the base portion 21, and the support hole 202 is formed in an annular shape on the outer peripheral side of the fitting hole 201. The fitting hole 201 passes through the drive gear 2 in the axial direction, and opens to one axial end surface 2a and the other axial end surface 2b of the drive gear 2. The axial length of the support hole 202 is shorter than that of the fitting hole 201, one end in the axial direction is opened on one axial end surface 2 a of the drive gear 2, and the other end in the axial direction is closed. It is a blind hole.

  Thus, the fitting hole 201 and the support hole 202 are formed so as to overlap in the axial direction of the drive gear 2. Here, “overlapping in the axial direction” means that in the axial direction of the drive gear 2, the range in which the fitting hole 201 is formed and the range in which the support hole 202 is formed overlap at least partially. . In the present embodiment, since the fitting hole 201 penetrates the drive gear 2 in the axial direction, the entire support hole 202 overlaps with the fitting hole 201 and the driving gear 2 in the axial direction.

  The fitting hole 201 has a non-circular cross section perpendicular to the axial direction of the drive gear 2, and in the present embodiment, the shape of the fitting hole 201 in this cross section is rectangular. The shape of the fitting hole 201 is a shape corresponding to the fitting portion 810 of the motor shaft 81. By fitting the fitting portion 810 of the motor shaft 81 into the fitting hole 201, the drive gear 2 and the motor shaft 81 are fitted. And are connected so as not to rotate relative to each other. In the present embodiment, the fitting portion 810 of the motor shaft 81 is a rod having a rectangular cross section, and is fitted into the fitting hole 201 over substantially the entire axial direction thereof.

  The driven gear 3 integrally includes a cylindrical base portion 31 having a shaft hole 30 formed in the center and a plurality of gear teeth 32 provided radially from the base portion 31. The shaft hole 30 penetrates the base portion 31 in the axial direction, and opens to one axial end surface 3 a and the other axial end surface 3 b of the driven gear 3. The gear teeth 32 of the driven gear 3 and the gear teeth 22 of the drive gear 2 mesh with each other. The driven gear 3 receives the rotational force from the drive gear 2 by this meshing and rotates in the pump chamber 400.

  The housing 4 is provided on a cylindrical portion 41 having an inner surface 41 a facing the tooth tip surfaces 22 a and 32 a of the gear teeth 22 and 32 of the drive gear 2 and the driven gear 3, and one axial direction side and the other side of the cylindrical portion 41. First and second side plate portions 42, 43 as a pair of side plate portions, and first and second support portions 44, 45 projecting from the first side plate portion 42 toward the second side plate portion 43, The first holding portion 46 that holds the stator 85 of the motor portion 8 and the outer ring 821 of the first rolling bearing 82, and the second holding portion 47 that holds the outer ring 831 of the second rolling bearing 83. doing. The first and second support portions 44 and 45 are erected vertically to the erected surface 42 a of the first side plate portion 42. The first and second side plate portions 42 and 43 are both flat, and the first side plate portion 42 is disposed on the driving force generating mechanism 80 side.

  In the present embodiment, the housing 4 includes three members including the main body 40. The main body 40 integrally includes a cylindrical portion 41, a first side plate portion 42, first and second support portions 44 and 45, and a first holding portion 46. Each part of the main body 40 is formed by cutting using a cutting tool such as an end mill. However, the present invention is not limited thereto, and the main body 40 may be constituted by a plurality of parts integrated by, for example, press fitting. The second side plate portion 43 is separate from the main body portion 40 and is fixed to the cylindrical portion 41 of the main body portion 40 by a plurality of bolts 48. The bolt 48 is inserted into a bolt insertion hole 430 (shown in FIG. 2) formed in the second side plate portion 43 and screwed into a screw hole 410 formed in the cylinder portion 41. The second holding portion 47 is separate from the main body portion 40 and is fixed to the first holding portion 46 by a plurality of bolts 49.

  The cylinder portion 41 is formed with a suction port 411 for sucking hydraulic oil into the pump chamber 400 and a discharge port 412 for discharging hydraulic oil from the pump chamber 400. The first side plate portion 42 and the second side plate portion 43 form a pump chamber 400 together with the cylinder portion 41. The first and second support portions 44 and 45 protrude into the pump chamber 400 along the axial direction of the drive gear 2 and the driven gear 3. The first side plate portion 42 is formed with an insertion hole 420 through which the first shaft portion 811 of the motor shaft 81 is inserted. A seal member 84 that is in sliding contact with the first shaft portion 811 is attached to the inner peripheral surface of the insertion hole 420.

  The first support portion 44 is fitted into the support hole 202 of the drive gear 2 to support the drive gear 2. In the present embodiment, as shown in FIGS. 2 and 4, the first support portion 44 is formed in an arc shape. The first support portion 44 supports the drive gear 2 on the high pressure chamber 402 side of the low pressure chamber 401 on the suction port 411 side and the high pressure chamber 402 on the discharge port 412 side in the pump chamber 400, and Is partially open in the radial direction. With this configuration, the first support portion 44 can be easily processed by the cutting tool. The second support portion 45 has a cylindrical shape and is fitted in the shaft hole 30 of the driven gear 3 to support the driven gear 3.

  The first support portion 44 is inserted into the support hole 202 of the drive gear 2 to a position closer to the second side plate portion 43 than the center portion of the gear teeth 22 in the tooth trace direction. Further, the second support portion 45 is inserted into the shaft hole 30 of the driven gear 3 to a position closer to the second side plate portion 43 than the center portion in the tooth trace direction of the gear teeth 32. And the inclination with respect to the axial direction of the drive gear 2 and the driven gear 3 is suppressed by this structure. Here, the central portion in the tooth trace direction means a position that bisects the range in which the gear teeth 22 and 32 are provided in the axial direction of the drive gear 2 and the driven gear 3 in the axial direction. Is shown by a two-dot chain line. Further, in FIG. 1, the rotation axes of the drive gear 2 and the driven gear 3 are shown by alternate long and short dash lines.

  The first and second bearings 5 and 6 are sliding bearings formed in a cylindrical shape. The first bearing 5 is disposed between the inner surface of the support hole 202 of the drive gear 2 and the first support portion 44. The second bearing 6 is disposed between the inner surface of the shaft hole 30 of the driven gear 3 and the second support portion 45. The first bearing 5 is press-fitted into the outer peripheral surface 202 a among the outer peripheral surface 202 a and the inner peripheral surface 202 b of the support hole 202 of the drive gear 2, and rotates integrally with the drive gear 2. The second bearing 6 is press-fitted into the inner peripheral surface of the shaft hole 30 of the driven gear 3 and rotates integrally with the driven gear 3. The inner diameter of the first bearing 5 is slightly larger than the outer diameter of the first support portion 44, and the inner diameter of the second bearing 6 is slightly larger than the outer diameter of the second support portion 45. An annular gap is formed between the inner peripheral surface 202 b of the support hole 202 of the drive gear 2 and the first support portion 44.

  The side plate 7 is disposed between the drive gear 2 and the driven gear 3 and the second side plate portion 43 of the housing 4, and the front (front) surface 7 a is the axial end surface 2 b of the drive gear 2 and the driven gear 3. Is in contact with the axial end surface 3b. Further, the side plate 7 has a longitudinal dimension along the direction in which the drive gear 2 and the driven gear 3 are arranged substantially the same as the length of the pump chamber 400 in the same direction, and is orthogonal to the longitudinal direction at the center in the longitudinal direction. The length in the short direction is shorter than the length of the pump chamber 400 in the same direction.

  A groove 7c that is recessed in the thickness direction of the side plate 7 is formed on the back surface 7b of the side plate 7, and a rubber side seal 71 is disposed in the groove 7c in a state compressed in the thickness direction of the side plate 7. Has been. The side seal 71 is elastically contacted with the second side plate portion 43 and divides the pump chamber 400 into a low pressure chamber 401 on the suction port 411 side and a high pressure chamber 402 on the discharge port 412 side. Further, the surface 7 a of the side plate 7 is pressed against the axial end surface 2 b of the drive gear 2 and the axial end surface 3 b of the driven gear 3 by the restoring force of the side seal 71. Also, the driving gear 2 and the driven gear 3 are pressed against the standing surface 42 a of the first side plate portion 42 by the pressing force received from the side plate 7, with the axial end surfaces 2 a and 3 a on the opposite side of the side plate 7. Yes. The standing surface 42 a of the first side plate portion 42 is a flat surface facing the surface 7 a of the side plate 7 with the pump chamber 400 interposed therebetween.

(External gear pump operation)
In the external gear pump 1 configured as described above, the driving oil 2 and the driven gear 3 are rotated in the pump chamber 400 by the driving force of the motor unit 8, so that the hydraulic oil sucked from the suction port 411 is discharged from the discharge port 412. Discharge. In FIG. 4, the rotation directions of the drive gear 2 and the driven gear 3 are indicated by arrows.

  The inner surface 41a of the cylindrical portion 41 of the housing 4 and the tooth tip surfaces 22a and 32a of the plurality of gear teeth 22 and 32 of the drive gear 2 and the driven gear 3 are connected via a slight gap (seal gap) of 3 to 4 μm, for example. Face each other. Oil chambers S are formed between two gear teeth 22 adjacent to each other in the circumferential direction of the drive gear 2 and between two gear teeth 32 adjacent to each other in the circumferential direction of the driven gear 3. The hydraulic oil sucked from the suction port 411 moves from the low pressure chamber 401 to the high pressure chamber 402 by the oil chamber S as the drive gear 2 and the driven gear 3 rotate. In the high pressure chamber 402, the pressure of the hydraulic oil is increased by the volume change caused by the gear teeth 22 of the drive gear 2 and the gear teeth 32 of the driven gear 3 meshing, and the hydraulic oil is discharged from the discharge port 412.

(Operation and effect of the first embodiment)
In the first embodiment described above, the drive gear 2 is rotatably supported by the first support portion 44 inserted into the support hole 202 and one end portion of the motor is fitted in the fitting hole 201. The shaft 81 is rotationally driven, and the fitting hole 201 and the support hole 202 are formed so as to overlap in the axial direction of the drive gear 2. The driven gear 3 is rotatably supported by a second support portion 45 inserted into the shaft hole 30. Thereby, the drive gear 2 and the driven gear 3 can be reduced in size in the axial direction, and the external gear pump 1 can be reduced in size. In addition, since the drive gear 2 and the motor shaft 81 are connected by being directly fitted together without any other member, the connection strength between the drive gear 2 and the motor shaft 81 is sufficiently ensured. Is possible.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 5 is a cross-sectional view showing the external gear pump 1A according to the present embodiment. FIG. 6 is a perspective view showing motor shaft 81 of external gear pump 1A according to the present embodiment. 5 and the subsequent drawings, members having the same functions as those described in the first embodiment are denoted by the same reference numerals as those in FIGS. 1 to 4 and redundant description is omitted. To do.

  The external gear pump 1A according to the present embodiment is different in the connection structure between the motor shaft 81 and the drive gear 2 and the structure of the housing 4. Hereinafter, regarding the external gear pump 1A, differences from the external gear pump 1 according to the first embodiment will be mainly described.

  Similarly to the first embodiment, the motor shaft 81 of the present embodiment includes a fitting portion 810 that fits into the drive gear 2 and first to third shaft portions 811 to 813 having different outer diameters. Although it has integrally, the shape of the fitting part 810 differs from 1st Embodiment. In the present embodiment, the fitting portion 810 includes a cylindrical portion 810b having a plurality of spline protrusions 810a formed on the outer peripheral surface, and an annular plate-like connecting portion 810c that connects the cylindrical portion 810b and the first shaft portion 811. It is comprised.

  In the present embodiment, the fitting hole 201 of the drive gear 2 into which the cylindrical portion 810b of the fitting portion 810 is fitted is formed in an annular shape. The fitting hole 201 is formed with an engaging portion 201c in which a plurality of spline protrusions 810a are engaged in the circumferential direction. The fitting hole 201 is a blind hole that opens in the axial end surface 2a on the second side plate portion 42 side of the drive gear 2 and whose other end in the axial direction is closed.

  In the first embodiment, the first and second support portions 44 and 45 protrude from the first side plate portion 42 toward the second side plate portion 43, and the side plate 7 has the drive gear 2 and the driven gear. 3 and the second side plate portion 43, the first and second support portions 44 and 45 are moved from the second side plate portion 43 to the first side plate portion 42 in the present embodiment. The side plate 7 is disposed between the drive gear 2 and the driven gear 3 and the first side plate portion 42. The first and second support portions 44 and 45 are both cylindrical, and are perpendicular to the flat standing surface 43 a of the second side plate portion 43 that faces the surface 7 a of the side plate 7 via the pump chamber 400. It is erected.

  The side plate 7 is formed with an insertion hole 70 through which the fitting portion 810 of the motor shaft 81 is inserted. The side seal 71 is in elastic contact with the first side plate portion 42. Moreover, in this Embodiment, while the cylinder part 41, the 2nd side plate part 43, and the 1st and 2nd support parts 44 and 45 are integrally formed, the 1st side plate part 42 and the 1st The holding portion 46 is integrally formed. The first side plate portion 42 and the tube portion 41 are fastened by a bolt 48.

  The support hole 202 of the drive gear 2 is formed at the center of the base 21 and penetrates the drive gear 2 in the axial direction. The first bearing 5 is press-fitted into the inner peripheral surface of the support hole 202. Further, the second bearing 6 is press-fitted into the inner peripheral surface of the shaft hole 30 of the driven gear 3 as in the first embodiment. The fitting hole 201 is formed on the outer peripheral side of the support hole 202.

  Also in the present embodiment, the fitting hole 201 and the support hole 202 of the drive gear 2 are formed so as to overlap in the axial direction of the drive gear 2. Further, in the present embodiment, since the support hole 202 penetrates the drive gear 2 in the axial direction, the entire fitting hole 201 overlaps the support hole 202 and the drive gear 2 in the axial direction.

  According to the second embodiment described above, similarly to the first embodiment, the drive gear 2 and the driven gear 3 can be reduced in the axial direction, and the external gear pump 1A can be reduced in size. Become. In addition, since the drive gear 2 and the motor shaft 81 are connected by being directly fitted together without any other member, the connection strength between the drive gear 2 and the motor shaft 81 is sufficiently ensured. Is possible.

[Third Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS.

  FIG. 7 is a cross-sectional view showing the external gear pump 1B according to the present embodiment. FIG. 8 is a perspective view showing the second side plate portion 43 and the first and second support portions 44 and 45 according to the present embodiment.

  The circumscribed gear pump 1B according to the present embodiment is different from the first embodiment in that the first and second support portions 44 and 45 are configured integrally with the second side plate portion 43. Hereinafter, with respect to the external gear pump 1B, differences from the external gear pump 1 according to the first embodiment will be mainly described.

  In the first embodiment, the first and second support portions 44 and 45 are integrated with the first side plate portion 42 and protrude from the first side plate portion 42 toward the second side plate portion 43. In the present embodiment, the first and second support portions 44 and 45 are integrated with the second side plate portion 43, and the first side surface 43 a of the second side plate portion 43 is removed from the flat standing surface 43 a. Projecting vertically toward the side plate portion 42. The support hole 202 of the drive gear 2 into which the first support portion 44 is inserted opens in the axial end surface 2b that contacts the second side plate portion 43 and extends in the axial direction, and the other end portion in the axial direction is It is a closed blind hole. The first support portion 44 is cylindrical, and the second support portion 45 is columnar. The axial length of the first support portion 44 is shorter than the axial length of the second support portion 45 and is longer than half the axial thickness of the drive gear 2.

  In the first embodiment, the case where the side plate 7 is disposed between the drive gear 2 and the driven gear 3 and the second side plate portion 43 has been described. However, in the present embodiment, the side plate 7 Is disposed between the drive gear 2 and the driven gear 3 and the first side plate portion 42. The surface 7 a of the side plate 7 is pressed against the axial end surface 2 a of the drive gear 2 and the axial end surface 3 a of the driven gear 3 by the restoring force of the side seal 71.

  In the present embodiment, the first and second support portions 44 and 45 are configured integrally with the second side plate portion 43, and the second side plate portion 43 and the tube portion 41 are fastened by a plurality of bolts 48. Yes. The plurality of bolts 48 are inserted into bolt insertion holes 430 formed in the second side plate portion 43 and screwed into the screw holes of the cylinder portion 41.

  According to the third embodiment described above, the fitting hole 201 and the support hole 202 of the drive gear 2 are formed so as to overlap in the axial direction as in the first embodiment. The gear 2 and the driven gear 3 can be downsized in the axial direction, and the external gear pump 1B can be downsized. In addition, since the drive gear 2 and the motor shaft 81 are connected by being directly fitted together without any other member, the connection strength between the drive gear 2 and the motor shaft 81 is sufficiently ensured. Is possible.

(Appendix)
As mentioned above, although this invention was demonstrated based on embodiment, these embodiment does not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

  In addition, the present invention can be appropriately modified and implemented without departing from the gist thereof, and may be implemented by appropriately combining the configurations of the above embodiments. In each of the above embodiments, the case where the driving force generation mechanism 80 that generates a driving force by a magnetic force is used as a driving source for driving the driving gear 2 is not limited to this. The drive gear 2 may be driven by a part of the driving force of the driving source for traveling. In each of the above embodiments, the case where the single side plate 7 is disposed in the pump chamber 400 has been described. However, the present invention is not limited to this, and the side plates are respectively provided on both sides in the axial direction of the drive gear 2 and the driven gear 3. 7 may be arranged.

DESCRIPTION OF SYMBOLS 1,1A, 1B ... External gear pump 2 ... Drive gear 201 ... Fitting hole 202 ... Support hole 22 ... Gear tooth 22a ... Tooth tip surface 3 ... Drive gear 30 ... Shaft hole 32 ... Gear tooth 4 ... Housing 400 ... Pump chamber 41 ... cylinder part 41a ... inner surface 42 ... first side plate part 43 ... second side plate part 44 ... first support part 45 ... second support part 46 ... first holding parts 5, 6 ... first and second Bearing 80 ... Drive force generation mechanism (drive source)
81 ... Motor shaft (drive shaft) 85 ... Stator 86 ... Rotor

Claims (4)

A driving shaft that is rotated by a driving force of a driving source; a driving gear that is coupled to the driving shaft; a driven gear that is rotated by meshing with the driving gear; and a pump chamber that houses the driving gear and the driven gear. An external gear pump that draws fluid from the suction side and discharges it to the discharge side by rotation of the drive gear and the driven gear,
The housing is provided with a cylindrical portion having an inner surface facing the tooth tip surfaces of the gear teeth of the drive gear and the driven gear, and the pump chamber together with the cylindrical portion provided on one side and the other side of the cylindrical portion. A pair of side plates, a first support that supports the drive gear, and a second support that supports the driven gear,
The first support portion protrudes from one side plate portion of the pair of side plate portions toward the other side plate portion,
The drive gear has a fitting hole into which the drive shaft is fitted so as not to be relatively rotatable, and a support hole into which the first support portion is inserted,
The fitting hole and the support hole are formed so as to overlap in the axial direction of the drive gear,
External gear pump. In the drive gear, the fitting hole is formed at the center thereof, and the support hole is formed in an annular shape on the outer peripheral side of the fitting hole.
The external gear pump according to claim 1. The drive gear has the support hole formed in the center thereof, and the fitting hole is formed on the outer peripheral side of the support hole.
The external gear pump according to claim 1. As the driving source, a driving force generating mechanism that generates the driving force by a magnetic force acting between an annular stator held in the housing and a rotor disposed inside the stator,
The housing integrally includes a holding portion that holds the stator, the cylindrical portion, the one side plate portion, and the first and second support portions.
The external gear pump according to any one of claims 1 to 3.

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