JP2018189017A - External gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an external gear pump which enables downsizing.SOLUTION: In an external gear pump 1 having a driving gear 2 and a driven gear 3 and a pump housing 4, shaft holes 20, 30 are respectively formed at center parts of the driving gear 2 and the driven gear 3. The pump housing 4 has: a cylinder part 41 having an inner surface 41a facing top lands 22a, 32a of the driving gear 2 and the driven gear 3; first and second side plate parts 42, 45 forming a pump chamber 400 at both axial sides of the cylinder part 41; and first and second support parts 43, 44 which protrude from the first side plate part 42 toward the second side plate part 45, are fitted in the shaft holes 20, 30 of the driving gear 2 and the driven gear 3, and support the driving gear 2 and the driven gear 3. The driving gear 2 has: a gear part 23 formed with multiple gear teeth 22; and a shaft part 24 which is provided continuing into one axial end part of the gear part 23, and transmits a driving force of a motor part 12 to the gear part 23. The shaft part 24 is inserted into an insertion hole 450 formed at the second side plate part 45.SELECTED DRAWING: Figure 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. Although it is possible, since the drive shaft is inserted into the support journal of the drive gear, the support journal has a large diameter, and consequently, the drive gear and the driven gear are enlarged in the radial direction.

  Therefore, an object of the present invention is to provide a circumscribed gear pump that can be miniaturized.

  In order to achieve the above object, the present invention includes a drive gear that is rotationally driven by a drive source, a driven gear that rotates by meshing with the drive gear, and a pump chamber that houses the drive gear and the driven gear. A housing formed, and first and second bearings for smooth rotation of the drive gear and the driven gear, and the fluid is sucked from the suction side by the rotation of the drive gear and the driven gear. The drive gear and the driven gear each have gear teeth that mesh with each other, and a shaft hole is formed at the center thereof, and the housing includes the drive gear and the driven gear. A cylindrical portion having an inner surface facing the tooth tip surface of the gear tooth of the gear, and a first that is provided on one side and the other side in the axial direction of the cylindrical portion to form the pump chamber together with the cylindrical portion. And a second side plate portion, and projecting from the first side plate portion toward the second side plate portion, and fitted into the shaft holes of the drive gear and the driven gear, respectively, so that the drive gear and the driven gear are The driving gear is provided continuously with a gear portion in which the gear teeth are formed on an outer peripheral surface and one axial end portion of the gear portion; There is provided an external gear pump having a shaft portion that transmits a driving force of a source to the gear portion, and the shaft portion is inserted through an insertion hole formed in the second side plate portion.

  According to the present invention, it is possible to reduce the size of the external gear pump.

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 which shows the pump part of a circumscribed gear pump. It is a perspective view which shows a one part component of a pump part. It is explanatory drawing shown in order to demonstrate operation | movement of an external gear pump. It is a disassembled perspective view which shows the structure of the external gear pump which concerns on a comparative example. It is a perspective view which fractures | ruptures a part of cylinder part and shows the main-body part of the pump housing which concerns on the 2nd Embodiment of this invention. It is sectional drawing of the external gear pump which concerns on 2nd Embodiment. It is a perspective view which fractures | ruptures and shows a part of pump housing and bearing which concern on the 3rd Embodiment of this invention. (A) And (b) is sectional drawing which shows the external gear pump which concerns on the 4th Embodiment of this invention.

[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 a pump portion of the external gear pump. FIG. 3 is a perspective view showing a state in which some components of the pump unit are viewed from the side opposite to FIG. FIG. 4 is an explanatory diagram for explaining the operation of the external gear pump. 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 has a pump unit 11 and a motor unit 12 as a drive source for driving the pump unit 11. The pump unit 11 includes a drive gear 2 that is rotationally driven in one direction by the motor unit 12, 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 housed. The formed pump housing 4, first and second bearings 5 and 6 for smooth rotation of the drive gear 2 and the driven gear 3, and a plate-like side plate 7 made of resin, The hydraulic oil is sucked from the suction side by the rotation of the driven gear 3 and discharged to the discharge side.

  The motor unit 12 includes a motor shaft 81 as a drive shaft, a motor housing 82, an annular stator 83 held by the motor housing 82, a rotor 84 disposed inside the stator 83, and a motor shaft 81. The first and second rolling bearings 85 and 86 are supported. The stator 83 includes an iron core 831, an insulator 832 attached to the iron core 831, and a winding 833 wound around the insulator 832. An exciting current is supplied to the winding 832 from a control device (not shown). The rotor 84 has a core 841 fixed to the motor shaft 81 and a plurality of permanent magnets 842 attached to the outer peripheral surface of the core 841. The motor unit 12 generates a driving force by a magnetic force acting between the stator 83 and the rotor 84.

  The motor housing 82 has a cylindrical main body portion 821 to which the iron core 831 of the stator 83 is fixed, and a lid portion 822 that closes an end portion of the main body portion 821 opposite to the pump portion 11. 821 and the lid 822 are fastened by a plurality of bolts 823. The main body portion 821 supports the first rolling bearing 85, and the lid portion 923 supports the second rolling bearing 85.

  The first rolling bearing 85 supports the motor shaft 81 on the pump portion 12 side of the rotor 84, and the second rolling bearing 86 supports the motor shaft 81 on the opposite side of the rotor 84 from the pump portion 12. doing. The first and second rolling bearings 85 and 86 are ball bearings having outer rings 851 and 861, inner rings 852 and 862, and a plurality of spherical rolling elements 853 and 863, respectively.

  The drive gear 2 includes a cylindrical base portion 21 having a shaft hole 20 formed in the center, a gear portion 23 including a plurality of gear teeth 22 provided radially from the base portion 21, and one axial end portion of the gear portion 23. Are integrally provided with a cylindrical shaft portion 24 that is provided continuously with the projection 25 that is erected on the end surface of the shaft portion 24 opposite to the gear portion 23. The shaft portion 24 is aligned with the base portion 21 in the axial direction, and the outer diameter thereof is larger than the inner diameter of the shaft hole 20. The shaft hole 20 is a blind hole that is closed at one end by the shaft portion 24 and opens to the end surface of the base portion 21 opposite to the shaft portion 24.

  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 both sides thereof open to the axial end surface 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.

  In the driving gear 2, the driving force of the motor unit 12 received from the protrusion 25 is transmitted to the gear unit 23 by the shaft unit 24 to rotate the driven gear 3. The protrusion 25 of the drive gear 2 and the motor shaft 81 are connected via a coupling 87 that allows misalignment such as misalignment. The coupling 87 is accommodated in a through hole 820 formed in the main body portion 821 of the motor housing 82.

  The pump housing 4 includes a cylindrical portion 41 having an inner surface 41a facing the tooth tip surfaces 22a and 32a of the gear teeth 22 and 32 of the drive gear 2 and the driven gear 3, and a flat plate provided on one axial side of the cylindrical portion 41. A first side plate portion 42 having a shape, first and second support portions 43 and 44 projecting from the first side plate portion 42 into the tube portion 41, and the other side in the axial direction of the tube portion 41. A first side plate portion 42 and a second side plate portion 45 facing each other. The first side plate portion 42 and the second side plate portion 45 form a pump chamber 400 together with the cylinder portion 41. Each of the first and second support portions 43 and 44 has a cylindrical shape, and extends in parallel with each other. 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 and second support portions 43 and 44 protrude from the first side plate portion 42 toward the second side plate portion 45 and are fitted into the shaft holes 20 and 30 of the drive gear 2 and the driven gear 3 to drive. The gear 2 and the driven gear 3 are supported. The first support portion 43 is fitted in the shaft hole 20 of the drive gear 2 to a position closer to the second side plate portion 45 than the center portion of the gear teeth 22 in the tooth trace direction. Further, the second support portion 44 is fitted in the shaft hole 30 of the driven gear 3 to a position closer to the second side plate portion 45 than the center portion of the gear teeth 32 in the tooth trace direction.

  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. In the present embodiment, the first and second support portions 43 and 44 are disposed in the shaft holes 20 and 30 of the drive gear 2 and the driven gear 3 in substantially the whole tooth direction of the gear teeth 22 and 32 (90% or more). Range).

  In the present embodiment, the pump housing 4 is a second body which is a separate body from the main body 40 in which the first side plate portion 42 is integrally provided with the cylinder portion 41 and the first and second support portions 43 and 44. The side plate portion 45 is configured to be fastened by a bolt 46 as a fastening member. Thus, by forming the cylinder part 41, the 1st side-plate part 42, and the 1st and 2nd support parts 43 and 44 integrally, the dimensional accuracy between each part can be improved, and the pump chamber 400 is provided. It is possible to increase the pump efficiency by suppressing the leakage of hydraulic oil inside.

  The main body 40 is formed with a pump chamber 400 and first and second support portions 43 and 44 by cutting using a tool such as an end mill. However, the main body 40 is not limited thereto, and for example, the first and second support portions 43 and 44 are respectively press-fitted into a pair of fitting holes formed in the first side plate portion 42 and the first side plate portion. You may integrate by pressing-in 42 to the cylinder part 41. FIG. In FIG. 2, for convenience, the first side plate portion 42, the first and second support portions 43 and 44, and the cylindrical portion 41 are illustrated separately.

  The second side plate portion 45 is formed with an insertion hole 450 through which the shaft portion 24 of the drive gear 2 is inserted. Between the inner peripheral surface of the insertion hole 450 and the outer peripheral surface of the shaft portion 24, a seal member 47 for preventing leakage of hydraulic oil is disposed. The second side plate portion 45 is fastened to the main body portion 821 of the motor housing 82 by a plurality of bolts 48 (see FIG. 1).

  The 1st and 2nd bearings 5 and 6 arrange | positioned on the outer periphery of the 1st and 2nd support parts 43 and 44 are sliding bearings formed in the cylindrical shape. The first bearing 5 is disposed between the inner surface of the shaft hole 20 of the drive gear 2 and the first support portion 43. 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 44. The first bearing 5 is press-fitted into the shaft hole 20 of the drive gear 2 and rotates integrally with the drive gear 2. The second bearing 6 is press-fitted into 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 43, and the inner diameter of the second bearing 6 is slightly larger than the outer diameter of the second support portion 44. Further, the outer diameter of the first bearing 5 is smaller than the outer diameter of the shaft portion 24 of the drive gear 2.

  The side plate 7 is disposed between the gear portion 23 and the driven gear 3 of the drive gear 2 and the second side plate portion 45 of the pump housing 4. The side plate 7 is formed with a through hole 70 through which the shaft portion 24 of the drive gear 2 is inserted. The through hole 70 opens in the front surface 7a on the gear portion 23 and the driven gear 3 side of the drive gear 2 and the back surface 7b on the second side plate portion 45 side. The side plate 7 has a dimension in the longitudinal direction along the direction in which the drive gear 2 and the driven gear 3 are arranged substantially the same as the length in the same direction of the pump chamber 400, and a short portion perpendicular to the longitudinal direction in the center in the longitudinal direction. The length in the hand direction is shorter than the length in the same direction of the pump chamber 400. Therefore, when the second side plate portion 45 is viewed from the first side plate portion 42 side, there is an area where the second side plate portion 45 is not covered with the side plate 7 in the vicinity of the suction port 411 and the discharge port 412. To do.

  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 45 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 23 a of the gear portion 23 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 addition, the gear portion 23 and the driven gear 3 of the driving gear 2 are pressed against the first side plate portion 42 by the pressing force received from the side plate 7 on the side opposite to the side plate 7.

  A part of the surface 7 a of the side plate 7 is a sliding surface 7 d on which the axial end surface 23 a of the gear portion 23 slides by the rotation of the drive gear 2, and the other part of the surface 7 a by the rotation of the driven gear 3. This is a sliding surface 7e on which the axial end surface 3a slides. The sliding surface 7 d is elastically pressed against the axial end surface 23 a of the gear portion 23 of the drive gear 2, and the sliding surface 7 d is elastically pressed against the axial end surface 3 a of the driven gear 3.

(External gear pump operation)
In the external gear pump 1 configured as described above, the driving gear 2 and the driven gear 3 are rotated in the pump chamber 400 by the driving force of the motor unit 12, 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 cylinder part 41 in the pump 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. And 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.

(Comparative example)
FIG. 5 is an exploded perspective view showing the configuration of the external gear pump 9 according to the comparative example. The external gear pump includes a driving gear 91 and a driven gear 92, first and second side plates 93 and 94 that support the driving gear 91 and the driven gear 92, the driving gear 91 and the driven gear 92, and the first and second gears. The pump housing 95 that accommodates the side plates 93 and 94, a pair of sliding bearings 96 that facilitate the rotation of the drive gear 91, and a pair of sliding bearings 97 that facilitate the rotation of the driven gear 92 are provided.

  The drive gear 91 integrally includes a gear portion 912 having a plurality of gear teeth 911 formed on the outer peripheral surface, and shaft portions 913 and 914 provided on one side and the other side of the gear portion 912 in the axial direction. . The shaft part 914 is connected to a motor shaft of a motor part (not shown), and rotates by receiving a driving force of the motor part. The driven gear 92 integrally includes a gear portion 922 having a plurality of gear teeth 921 formed on the outer peripheral surface and shaft portions 923 and 924 provided on one side and the other side of the gear portion 922 in the axial direction. The teeth 921 are rotated by meshing with the gear teeth 911 of the drive gear 91.

  The first side plate 93 is formed with a support hole 931 that supports the shaft portion 913 of the drive gear 91 and a support hole 932 that supports the shaft portion 923 of the driven gear 92. The second side plate 94 is formed with a support hole 941 for supporting the shaft portion 914 of the drive gear 91 and a support hole 942 for supporting the shaft portion 924 of the driven gear 92. Slide bearings 96 and 97 are accommodated in the support holes 931 and 932 of the first side plate 93, respectively. Similarly, slide bearings 96 and 97 are accommodated in the support holes 941 and 942 of the second side plate 94, respectively.

  A side seal 933 is attached to the first side plate 93. Although not shown, a similar side seal is also attached to the second side plate 94. The pump housing 95 is closed at both axial ends by unillustrated lid members.

  The external gear pump 9 operates in the same manner as the external gear pump 1 according to the first embodiment, and discharges hydraulic oil sucked from the suction port 951 from a discharge port (not shown). When this external gear pump 9 is compared with the external gear pump 1 according to the first embodiment, the drive gear 91 has shaft portions 913 and 914 at both axial end portions, and the driven gear 92 has shaft portions at both axial end portions. Since it has 923,924, the pump housing 95 will enlarge in an axial direction. Further, since the first and second side plates 93 and 94 having thicknesses corresponding to the axial lengths of the shaft portions 913 and 914 of the drive gear 91 and the shaft portions 923 and 924 of the driven gear 92 are required, the external gear pump The weight increases from 1.

(Operation and effect of the first embodiment)
According to the first embodiment described above, the drive gear 2 and the driven gear 3 are supported by the first and second support portions 43 and 44 that are fitted into the shaft holes 20 and 30 formed in the center thereof. Therefore, the axial length of the pump part 11 can be shortened, and the size can be reduced as compared with the external gear pump 9 according to the comparative example. Further, since the driving force of the motor unit 12 is transmitted to the gear unit 23 of the drive gear 2 by the shaft unit 24 that is continuously provided at one end of the gear unit 23 in the axial direction. The size of the pump portion 11 in the radial direction can be reduced as compared with the case where the drive shaft is inserted into the support journal that supports the drive gear like the case.

  Further, according to the present embodiment, the first support portion 43 is fitted into the shaft hole 20 of the drive gear 2 to a position closer to the second side plate portion 45 than the central portion of the gear teeth 22 in the tooth trace direction, And since the 2nd support part 44 is inserted in the shaft hole 30 of the driven gear 3 to the position close | similar to the 2nd side plate part 45 rather than the center part of the tooth trace direction of the gear tooth 32, the 1st and 2nd The bearing load capacity by the bearings 5 and 6 can be sufficiently ensured, and even if the driving gear 2 and the driven gear 3 receive the pressure of the hydraulic oil in the high-pressure chamber 402, the rotating shafts thereof are the first and second support portions. Inclination with respect to the axial direction of 43 and 44 is suppressed.

  Further, according to the present embodiment, the first side plate portion 42 of the pump housing 4 is integrally provided with the cylinder portion 41 and the first and second support portions 43 and 44, so that the first support portion 43, the distance between the tooth tip surface 22 a of the gear tooth 22 of the drive gear 2 supported by 43 and the inner surface 41 a of the cylindrical portion 41, and the tooth tip surface of the gear tooth 32 of the driven gear 3 supported by the second support portion 44. 32a and the inner surface 41a of the cylinder part 41 can be maintained appropriately, and high pump efficiency can be obtained by suppressing leakage of hydraulic fluid between the oil chambers S, and the number of parts can be reduced to reduce the assembly man-hours. It becomes possible to reduce.

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

  FIG. 6 is a perspective view showing the main body portion 40 of the pump housing 4 according to the present embodiment with a part of the cylindrical portion 41 cut away. FIG. 7 is a cross-sectional view of the external gear pump 1 of the present embodiment including the pump housing 4 shown in FIG. 6, (a) is a cross-section including the rotational axis of the drive gear 2, and (b) is the driven gear 3. A cross section including the rotation axis is shown. 6 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.

  In the present embodiment and third and fourth embodiments to be described later, a configuration for causing the lubricating oil to flow in the shaft hole 20 of the drive gear 2 and the shaft hole 30 of the driven gear 3 is provided. In the present embodiment, a plurality of oil grooves 431 and 441 are formed on the outer peripheral surfaces 43a and 44a of the first and second support portions 43 and 44, and the inside of the first and second support portions 43 and 44 is formed. The circulation holes 432 and 442 for circulating the hydraulic oil flowing through the oil grooves 431 and 441 are formed. The outer peripheral surfaces 43 a and 44 a of the first and second support portions 43 and 44 are opposing surfaces that oppose the inner peripheral surfaces 5 a and 6 a of the first and second bearings 5 and 6.

  In FIG. 6, the rotation direction of the drive gear 2 with respect to the first support portion 43 and the rotation direction of the driven gear 3 with respect to the second support portion 44 are indicated by arrows. In the illustrated example of FIG. 6, three oil grooves 431 are formed at equal intervals in the first support portion 43, and three oil grooves 441 are also formed at equal intervals in the second support portion 44. Yes. The oil groove 431 of the first support portion 43 extends in a direction inclined with respect to the axial direction and the rotation direction of the drive gear 2, and the hydraulic oil flows when the first bearing 5 rotates together with the drive gear 2. Let Further, the oil groove 441 of the second support portion 44 extends in a direction inclined with respect to the axial direction and the rotational direction of the driven gear 3, and the second bearing 6 rotates together with the driven gear 3 so that the hydraulic oil is rotated. Fluidize.

  The inclination direction of the oil groove 431 of the first support portion 43 is a direction that becomes the rear side in the rotation direction of the drive gear 2 toward the tip end side of the first support portion 43. Further, the inclination direction of the oil groove 441 of the second support portion 44 is a direction that becomes the rear side in the rotational direction of the driven gear 3 toward the distal end side of the second support portion 44. For this reason, hydraulic oil flows to the tip side (the second side plate part 45 side) of the first and second support parts 43 and 44 by the rotation of the drive gear 2 and the driven gear 3.

  The oil grooves 431 and 441 are formed only on the low-pressure chamber 401 side among the low-pressure chamber 401 side and the high-pressure chamber 402 side on the outer peripheral surfaces 43 a and 44 a of the first and second support portions 43 and 44. This is designed so that the surface pressure at the time of supporting the drive gear 2 and the driven gear 3 that have received the pressure of the hydraulic oil in the high-pressure chamber 402 does not become excessive. That is, during the operation of the external gear pump 1, the drive gear 2 and the driven gear 3 rotate toward the low pressure chamber 401 side as shown in FIGS. 7A and 7B due to the pressure of the hydraulic oil in the high pressure chamber 402. When the oil grooves 431 and 441 are provided on the side receiving this pressure, the outer circumferential surfaces 43a and 44a of the first and second support portions 43 and 44 and the first bearings 5 and 6 are formed by the oil grooves 431 and 441. The contact area with the inner peripheral surfaces 5a and 6a becomes narrow, and the contact surface pressure increases. In the present embodiment, by forming the oil grooves 431 and 441 on the low pressure chamber 401 side, the contact area between the first and second support portions 43 and 44 and the first and second bearings 5 and 6 is reduced. The grooves 431 and 441 are prevented from narrowing.

  7A and 7B, the left side of the drawing corresponds to the high pressure chamber 402 side, and the right side of the drawing corresponds to the low pressure chamber 401 side. The inner peripheral surface 5a of the first bearing 5 abuts on the high pressure chamber 402 side of the first support portion 43, and the inner diameter of the first bearing 5 and the outer diameter of the first support portion 43 on the low pressure chamber 401 side. A slight gap corresponding to the difference is formed. On the low pressure chamber 401 side of the first bearing 5, a plurality of oil grooves 431 generate a flow of hydraulic oil toward the distal end side of the first support portion 43. Further, the inner peripheral surface 6a of the second bearing 6 abuts on the high pressure chamber 402 side of the second support portion 44, and the inner diameter of the second bearing 6 and the second support portion 44 on the low pressure chamber 401 side. A slight gap corresponding to the difference from the outer diameter is formed. On the low pressure chamber 401 side of the second bearing 6, a plurality of oil grooves 441 generate a flow of hydraulic oil toward the distal end side of the second support portion 44.

  The oil grooves 431 and 441 are the outer peripheral surfaces 43a and 44a of the first and second support portions 43 and 44, and the inner peripheral surfaces 5a and 5a of the first and second bearings 5 and 6 during the operation of the external gear pump 1. It is provided in a range where it does not contact 6a. 7 (a) and 7 (b), the outer peripheral surfaces 43a and 44a of the first and second support portions 43 and 44 and the inner peripheral surfaces 5a and 6a of the bearings 5 and 6 are shown for clarity of explanation. The gap between is exaggerated.

  The hydraulic oil that has flowed into the oil grooves 431 and 441 leaks in the rotational direction of the bearings 5 and 6 while flowing along the extending direction of the first and second support portions 43 and 44, and the first and first The contact surfaces of the outer peripheral surfaces 43a, 44a of the second support portions 43, 44 and the inner peripheral surfaces 5a, 6a of the first and second bearings 5, 6 are lubricated. Thereby, wear and overheating on the contact surface are suppressed.

  An oil groove 431 is formed in the first support portion 43 over the entire axial direction from the base end portion on the first side plate portion 42 side to the tip end portion on the second side plate portion 45 side. Similarly, an oil groove 441 is formed in the second support portion 44 over the entire axial direction from the base end portion on the first side plate portion 42 side to the tip end portion on the second side plate portion 45 side. On the other hand, the axial lengths of the first and second bearings 5 and 6 are shorter than the axial lengths of the first and second support portions 43 and 44, and the inner surface 42a (pump of the first side plate portion 42). A space is formed between the chamber 400 side surface) and the axial end surfaces 5b and 6b of the first and second bearings 5 and 6 facing the inner surface 42a.

  The flow hole 432 of the first support part 43 has a vertical hole 433 that opens in the distal end surface 43 b of the first support part 43 and extends in the axial direction of the first support part 43, and the outer periphery of the first support part 43. The vertical hole 433 is open to the surface 43 a and extends in the radial direction of the first support part 43. The vertical hole 433 and the horizontal hole 434 communicate with each other inside the first support part 43. Similarly, the flow hole 442 of the second support portion 44 includes a vertical hole 443 that opens in the distal end surface 44b of the second support portion 44 and extends in the axial direction of the second support portion 44, and the second support portion. The horizontal holes 444 open to the outer peripheral surface 44 a of the second support portion 44 and extend in the radial direction of the second support portion 44, and the vertical holes 443 and the horizontal holes 444 communicate with each other inside the second support portion 44.

  The lateral hole 434 of the first support portion 43 opens between the inner surface 42a of the first side plate portion 42 and the axial end surface 5b of the first bearing 5 in the outer peripheral surface 43a. The lateral hole 444 of the second support portion 44 opens between the inner surface 42a of the first side plate portion 42 and the axial end surface 6b of the second bearing 6 in the outer peripheral surface 44a. Further, hydraulic oil is interposed between the front end surface 43b of the first support portion 43 and the bottom surface 20a of the shaft hole 20, and between the front end surface 44b of the second support portion 44 and the surface 7a of the side plate 7. A flowable gap is formed. As a result, the hydraulic oil easily flows into the vertical holes 433 and 443 of the flow holes 432 and 442, and the hydraulic oil easily flows out of the horizontal holes 434 and 444.

  In the present embodiment, the horizontal holes 434 and 444 open to the low pressure chamber 401 side, but the horizontal holes 434 and 444 may open to the high pressure chamber 402 side. In the present embodiment, one flow hole 432 and 442 is formed in each of the first and second support portions 43 and 44, but a plurality of flow holes 432 and 442 are formed in the first and second support portions 43 and 44. Flow holes 432 and 442 may be formed. Furthermore, if the contact area between the outer peripheral surfaces 43a, 44a of the first and second support portions 43, 44 and the inner peripheral surfaces 5a, 6a of the first and second bearings 5, 6 can be sufficiently secured. The plurality of oil grooves 431 and 441 may be provided on the high pressure chamber 402 side, or may be provided on both the low pressure chamber 401 side and the high pressure chamber 402 side.

  According to the present embodiment, the lubricating oil circulates in the shaft hole 20 of the drive gear 2 and the shaft hole 30 of the driven gear 3 in addition to the operations and effects of the first embodiment. It is possible to prevent the hydraulic oil in a part of the oil from overheating or running out of oil.

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

  FIG. 8 shows the main body 40 of the pump housing 4 according to the third embodiment of the present invention with a part of the cylindrical part 41 cut away, and part of the first and second bearings 5 and 6. It is a perspective view shown fractured. The first and second bearings 5 and 6 according to the present embodiment are cylindrical like the first embodiment, but in FIG. 8, the first and second bearings are semicircular when viewed in the axial direction. A part of the bearings 5 and 6 is shown.

  The first and second support portions 43 and 44 of the pump housing 4 according to the present embodiment are formed with flow holes 432 and 442 for circulating the hydraulic oil, as in the second embodiment. The oil grooves 431 and 441 are not formed on the outer peripheral surfaces 43a and 44a. On the other hand, in the present embodiment, the inner peripheral surface 5a of the first bearing 5 facing the outer peripheral surface 43a of the first support portion 43 extends in a direction inclined with respect to the axial direction and the rotational direction of the drive gear 2. A plurality of oil grooves 51 are formed in which the hydraulic oil flows when the first bearing 5 rotates together with the drive gear 2. In addition, the inner surface 6 a of the second bearing 6 that faces the outer peripheral surface 44 a of the second support portion 44 extends in a direction inclined with respect to the axial direction and the rotational direction of the driven gear 3. At the same time, a plurality of oil grooves 61 are formed through which the hydraulic oil flows as the second bearing 6 rotates. The plurality of oil grooves 51 and 61 extend over the entire axial direction of the inner peripheral surfaces 5a and 6a of the first and second bearings 5 and 6, and are formed at equal intervals in the circumferential direction.

  The direction of inclination of the oil groove 51 of the first bearing 5 is a direction that becomes the rear side in the rotation direction of the first bearing 5 toward the tip end side of the first support portion 43. In addition, the direction of inclination of the oil groove 61 of the second bearing 6 is a direction that becomes the rear side in the rotation direction of the second bearing 6 toward the tip end side of the second support portion 44. As a result, as in the second embodiment, the hydraulic fluid flows to the tip side of the first and second support portions 43 and 44 by the rotation of the drive gear 2 and the driven gear 3 by the driving force of the motor portion 12. Circulates through the circulation holes 432 and 442.

  Also in the present embodiment, as in the second embodiment, the hydraulic oil circulates in the shaft hole 20 of the drive gear 2 and the shaft hole 30 of the driven gear 3, so that a part of the shaft holes 20, 30 is inside. It is possible to prevent the hydraulic oil in the tank from overheating or running out of oil.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described with reference to FIG.

  FIGS. 9A and 9B are cross-sectional views showing the circumscribed gear pump 1 according to the fourth embodiment in cross sections corresponding to FIGS. 7A and 7B according to the second embodiment. .

  In the external gear pump 1 according to the present embodiment, oil grooves 431 and 441 are formed on the outer peripheral surfaces 43a and 44a of the first and second support portions 43 and 44 of the pump housing 4, but the flow holes 432 and 442 are formed. Is not formed. In the present embodiment, the hydraulic oil that has flowed through the oil groove 431 of the first support portion 43 flows into the shaft portion 24 of the drive gear 2 in the gap between the side plate 7 and the second side plate portion 45. Flow holes 241 and 242 are formed. The flow holes 241 and 242 have one end opening on the bottom surface 20 a of the shaft hole 20 and the other end opening on the outer peripheral surface 24 a of the shaft portion 24. 9A illustrates the case where two flow holes 241 and 242 are formed in the shaft portion 24, the number of flow holes is not particularly limited, and may be one or three or more. Good.

  Further, in the present embodiment, the flow hole 72 that causes the hydraulic fluid that has flowed through the oil groove 441 of the second support portion 44 to flow into the gap between the side plate 7 and the second side plate portion 45 in the side plate 7. Is formed. The flow hole 72 is formed at a position facing the front end surface 44 b of the second support portion 44 and penetrates between the front surface 7 a and the back surface 7 b of the side plate 7.

  The hydraulic fluid that has flowed from the flow holes 241 and 242 of the drive gear 2 and the flow hole 72 of the side plate 7 into the gap between the side plate 7 and the second side plate portion 45 is the peripheral portion of the side plate 7 and the cylindrical portion 41. Flows from the inner surface 41a to the first side plate portion 42 side. As in the other embodiments, the tip surface 43b of the first support portion 43 and the bottom surface 20a of the shaft hole 20, and the tip surface 44b of the second support portion 44 and the surface 7a of the side plate 7 are used. A gap in which hydraulic fluid can flow is formed.

  According to the present embodiment, the hydraulic fluid that has flowed in the shaft holes 20 and 30 of the drive gear 2 and the driven gear 3 toward the distal end sides of the first and second support portions 43 and 44 is transferred to the side plate 7 and the second plate. It flows into the gap between the side plate portions 45. Thereby, it is suppressed that hydraulic oil in a part in shaft holes 20 and 30 overheats, or oil outage occurs.

(Appendix)
The present invention has been described based on the first to fourth embodiments. However, these embodiments do not limit the invention according to the claims. 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 electric motor (motor unit 12) is used as the drive source for driving the drive gear 2 is described. However, the present invention is not limited to this, and for example, a drive source for traveling such as an automobile engine. The driving gear 2 may be driven by a part of the driving force. 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 both axial sides of the gear portion 23 of the drive gear 2 and the driven gear 3 are provided. The side plates 7 may be disposed respectively.

DESCRIPTION OF SYMBOLS 1 ... External gear pump 12 ... Motor part (drive source)
DESCRIPTION OF SYMBOLS 2 ... Drive gear 20 ... Shaft hole 22 ... Gear tooth 22a ... Tooth tip surface 23 ... Gear part 24 ... Shaft part 241, 242 ... Flow hole 3 ... Driven gear 30 ... Shaft hole 32 ... Gear tooth 32a ... Tooth tip surface 4 ... Pump housing (housing)
DESCRIPTION OF SYMBOLS 40 ... Main body 400 ... Pump chamber 41 ... Tube part 41a ... Inner surface 42 ... 1st side plate part 43 ... 1st support part 431 ... Oil groove 432 ... Flow hole 44 ... 2nd support part 441 ... Oil groove 442 ... Flow Hole 45 ... Second side plate portion 450 ... Insertion hole 46 ... Bolt (fastening member)
DESCRIPTION OF SYMBOLS 5 ... 1st bearing 6 ... 2nd bearing 51, 61 ... Oil groove (groove) 7 ... Side plate 7d, 7e ... Sliding surface 72 ... Flowing hole

Claims (9)

A drive gear that is rotated by a drive source; a driven gear that is rotated by meshing with the drive gear; a housing in which a pump chamber that houses the drive gear and the driven gear is formed; the drive gear and the driven An external gear pump that includes first and second bearings that facilitate rotation of the gear, and that sucks fluid from the suction side and discharges it to the discharge side by rotation of the drive gear and the driven gear;
The drive gear and the driven gear each have gear teeth that mesh with each other, and a shaft hole is formed at the center thereof,
The housing is provided with a cylindrical portion having an inner surface facing a tooth tip surface of the gear tooth of the drive gear and the driven gear, and is provided on one side and the other side in the axial direction of the cylindrical portion, and together with the cylindrical portion, the pump First and second side plate portions forming a chamber, projecting from the first side plate portion toward the second side plate portion, and being fitted into the shaft holes of the drive gear and the driven gear, respectively, and the drive First and second support portions for supporting the gear and the driven gear;
The drive gear includes a gear portion in which the gear teeth are formed on an outer peripheral surface, and a shaft portion that is provided continuously at one end portion in the axial direction of the gear portion and transmits the driving force of the drive source to the gear portion. And the shaft portion is inserted through an insertion hole formed in the second side plate portion,
External gear pump. The first support portion is fitted into the shaft hole of the drive gear to a position closer to the second side plate portion than a center portion in the tooth trace direction of the gear teeth,
The second support portion is inserted into the shaft hole of the driven gear to a position closer to the second side plate portion than a central portion in the tooth trace direction of the gear teeth.
The external gear pump according to claim 1. The first bearing is a slide bearing disposed between an inner surface of the shaft hole of the drive gear and the first support portion,
At least one of a surface facing the first support portion of the first bearing and a surface facing the first bearing of the first support portion with respect to the rotation direction of the drive gear. Grooves that extend in the inclined direction and flow the fluid are formed,
The external gear pump according to claim 1 or 2. A circulation hole for circulating the fluid that has flowed through the groove is formed in the first support portion.
The external gear pump according to claim 3. Between the second side plate portion of the housing and the gear portion of the drive gear, a side plate having a sliding surface that is elastically pressed against an axial end surface of the gear portion is disposed.
The shaft portion of the drive gear is formed with a flow hole for allowing the fluid flowing through the groove to flow into the gap between the side plate and the second side plate portion,
The external gear pump according to claim 3 or 4. The second bearing is a slide bearing disposed between an inner surface of the shaft hole of the driven gear and the second support portion,
At least one of the surface of the second bearing facing the second support and the surface of the second support facing the second bearing with respect to the rotational direction of the driven gear Grooves that extend in the inclined direction and flow the fluid are formed,
The external gear pump according to any one of claims 1 to 5. A circulation hole for circulating the fluid flowing through the groove is formed in the second support part.
The external gear pump according to claim 6. A side plate having a sliding surface that is elastically pressed against an axial end surface of the driven gear is disposed between the second side plate portion of the housing and the driven gear,
The side plate is formed with a flow hole for allowing the fluid flowing in the groove to flow into the gap between the side plate and the second side plate part,
The external gear pump according to claim 7. In the housing, the second side plate portion is fastened by a fastening member to a main body in which the cylindrical portion and the first and second support portions are integrally provided on the first side plate portion.
The external gear pump according to any one of claims 1 to 8.

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