JP3491540B2 - External gear pump - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an external gear pump used for supplying a fluid such as mechanical oil or applying a fluid pressure such as hydraulic pressure.

[0002]

2. Description of the Related Art By rotating a pair of externally toothed gears accommodated in a gear accommodating portion of a housing while meshing with each other, a fluid such as mechanical oil is sent from an intake portion communicating with the gear accommodating portion to a discharge portion. As the external gear pump, there is, for example, an external gear pump whose configuration is disclosed in Japanese Patent Laid-Open No. 9-287576.

In the external gear pump disclosed in Japanese Patent Laid-Open No. 9-287576, a bush is provided inside a housing constituting a casing. This bush is in contact with the outer peripheral surface of one shaft of the external gear. Also,
An inner seal and an outer seal are provided between the bush and the cover forming the casing, and a space surrounded by the inner seal and the outer seal serves as a pressure chamber. Part of the oil sent to the discharge part enters the pressure chamber due to the internal pressure in the discharge part, and the oil pressure of the oil that has entered the pressure chamber pushes the bush against the external gear, and further pushes the external gear onto the housing. It is pressed against the bottom portion, thereby preventing oil from leaking from the discharge portion to the suction portion via both ends in the axial direction of the external gear.

[0004]

In the external gear pump having the above structure, one shaft of the driving gear that receives the driving force first of the pair of external gears is rotatably supported by the bearing provided at the bottom of the housing. It is axially supported, and this shaft is not displaced along the direction orthogonal to the axis. Here, the inner diameter dimension of the gear accommodating portion of the housing of the external gear pump is larger than the outer diameter dimension of the outer tooth gear by at least the fitting tolerance with the outer tooth gear, and the outer diameter of each outer tooth gear at the bottom of the gear accommodating portion. If the shaft center of the bearing part such as a through hole formed for shaft support and the shaft center of each external gear are matched, a gap is created between the inner peripheral part of the gear housing part and the tooth tip of the external gear. Will be formed. Therefore, like the external gear pump disclosed in Japanese Patent Laid-Open No. 9-287576, when the shaft of the external gear is axially supported by a bearing or the like so as not to be displaced in the direction orthogonal to the axis, the external gear is Oil leaks from the discharge portion side to the suction portion side through the gap between the tooth tip of the tooth and the inner peripheral portion of the gear accommodating portion, and the discharge efficiency deteriorates.

In view of the above facts, an object of the present invention is to obtain an external gear pump capable of improving discharge efficiency.

[0006]

According to another aspect of the present invention, there is provided an external gear pump, wherein a first shaft is coaxially formed, and a driving force of external teeth which rotates around the first shaft when receiving a driving force. The gear and the second shaft are formed coaxially and mesh with the driving gear, and the driven gear having external teeth rotating around the second shaft as the driving gear rotates, and the driving gear. with the driven gear accommodating portion for accommodating the driven gear that meshes with the driving gear housing portion and the driving gear accommodated are formed respectively, the suction unit and communicating with each of said driving gear accommodating portion and the driven gear housing portion and a housings which discharge portion is formed that communicates with each of said driving gear accommodating portion and the driven gear housing portion on the opposite side to the suction unit via a meshing portion between the driven gear and the driving gear ,Previous
By the rotation of the driving gear and the driven gear,
With an external gear pump that sends the fluid drawn from the
The tip of the external tooth of the driving gear is accommodated in the driving gear.
The first shaft in the direction orthogonal to the axis until it abuts the inner peripheral part of the part
Of the driven gear and the first bearing portion axially displaceably supported.
The tip of the external tooth should touch the inner peripheral part of the driven gear accommodating part.
Supports the second shaft so as to be displaceable in the direction orthogonal to the axis.
A second bearing portion is provided in the housing, and the drive gear is provided.
And the negative at the suction part caused by the rotation of the driven gear.
Pressure and internal pressure at the discharge part increase
And displace the driven gear to move the outer teeth of the driving gear.
The driven gear is brought into contact with the drive gear accommodating portion and
Outer teeth of the driven gear accommodating portion are brought into contact with the inner peripheral portion thereof.
It is characterized by.

According to the external gear pump having the above structure, the driving gear rotates inside the driving gear housing formed in the housing, and the driven gear housed in the driven gear housing of the housing rotates as the driving gear rotates. , The fluid contained in the tooth spaces of the driving gear and the driven gear on the suction side is sent to the discharge side. The discharge part and the suction part are separated by the contact part between the inner peripheral part of the gear housing part and each tooth tip of the driving gear and the driven gear, and the meshing part of the driving gear and the driven gear. By the rotation of the, the fluid contained in the tooth groove of each gear is sent to the discharge part,
The internal pressure in the discharge portion rises, and the fluid is discharged from the discharge portion to the outside of the housing. On the other hand, the driving gear and the driven gear that rotate from the discharge side to the suction side have their outer teeth meshing with each other. Negative pressure is generated by the volume occupied by the teeth, whereby the fluid is sucked from the outside of the housing to the inside through the suction portion.

[0008] As described above, the internal pressure is increased in the discharge portion, the negative pressure is arising at inhalation portion, the inner pressure of the elevated discharge section
More addendum and tooth grooves of the gear Ru is pressed to the suction side. Here, the first shaft of the original moving gear is in contact with or in the displacement in the axial direction perpendicular addendum of the driving gear to the inner peripheral portion of the drive gear housing portion
Capable is pivotally supported by the first bearing portion. In addition , the second of the driven gear
Shaft axially supported by the second bearing portion so as to be displaceable in the axial direction perpendicular to the addendum of the driven gear abuts the inner peripheral portion of the driven gear housing portion
Ru is. Therefore, as described above, when the gears are pressed by <br/> pressure at increased discharge portion, the driving gear addendum
Displaced until it abuts the inner circumference of the drive gear housing
The tooth tip is pressed against the inner circumference of the drive gear accommodating part,
The yarn is displaced until the tip of the tooth comes into contact with the inner circumference of the driven gear housing.
The tooth tips are pressed against the inner peripheral portion of the driven gear accommodating portion . In this way, the tip of each external tooth is located inside the gear housing.
By being pressed against the portion, the suction portion and the discharge portion, which are in communication with each other via both gear accommodating portions, are completely partitioned. Thus, leakage of fluid to the suction portion side is prevented from the discharge side
It

In the external gear pump of the present invention, the first and second shafts are axially supported by the first and second bearing portions formed in the housing. However, in the conventional pressure loading type external gear pump, the side plates are be configured for supporting the respective shafts of the driving gear and the driven gear on the side, it is in principle possible to each shaft you displaceably supported along its axis orthogonal direction.

However, in the case of such a pressure loading type external gear pump, the shafts of the respective gears are inserted through the side plates, and the side plates are also partially inserted through the holes formed in the lid of the housing. It is a composition. Therefore, the gap between each gear accommodating portion and the tooth tip of each gear, the gap between the shaft and the hole portion of the side plate, and the gap between the side plate and the hole portion of the lid are in the direction orthogonal to the axis of each shaft. These dimensions are difficult to set because they are related to the amount of travel along them. On the other hand, in the present external gear pump, only the gaps between the driving gear accommodating portion and the driven gear accommodating portion and the tips of the gears, and the displaceable amounts of the first and second shafts and the first and second bearing portions are limited. Since it is related to the movement amount of each gear, it is easy to set the dimensions . The external gear pump according to claim 2 is the external gear pump according to claim 1.
In the present invention described, the first shaft and second shaft in towards the axial direction of the opposite driving gear and driven gear, provided with a said driving gear and the side plate disposed adjacent to the driven gear, A discharge pressure introducing passage that communicates with the discharge portion and introduces the internal pressure of the discharge portion to the opposite side of the driving gear and the driven gear of the side plate is formed in the housing, and the discharge pressure introducing passage is formed through the discharge pressure introducing passage. The side plate is provided with a pressing force acting portion that presses the side plate toward the suction portion side by the discharge pressure introduced to the side plate opposite to the driving gear and the driven gear, and the discharge pressure received by the pressing force acting portion is provided . Due to
The side plate is located on the suction side of the driving gear accommodating portion and the driven gear accommodating portion.
It is characterized in that it is pressed against the inner peripheral part of .

In the external gear pump having the above structure, the side plates are arranged adjacent to the driving gear and the driven gear on the axial side of the driving gear and the driven gear opposite to the first and second shafts, When the fluid on the discharge side is introduced to the side opposite to the driving gear and the driven gear via the side plate by the internal pressure increased on the discharge side via the discharge pressure introducing passage formed in the housing, this discharge pressure is generated on the side plate. Against the driving gear and the driven gear, the side plates press the driving gear against the bottom of the driving gear housing and the driven gear against the bottom of the driven gear housing. As a result, the gap between each gear and the bottom of each gear accommodating portion is small or eliminated, so that the fluid leaks from the discharge part to the suction part through each gear and the bottom of each gear accommodating part. Less or no, and as a result, the ejection efficiency is improved.

Here, in this external gear pump, the side plate is provided with a pressing force acting portion, and when the above-mentioned discharge pressure acts on this pressing force acting portion, the side plate is displaced toward the suction portion side. As a result, the side plate is pressed against the inner peripheral portions of the driving gear accommodating part and the driven gear accommodating part on the suction part side, and the space in the portion where the side plate is provided is partitioned by the side plate into the discharge part side and the suction part side. . Therefore, leakage of fluid from the discharge portion side to the suction portion side via the outer peripheral portion of the side plate and the side plate and the side opposite to each gear is prevented or reduced, and the discharge efficiency is further improved.

[0013]

FIG. 2 is an exploded perspective view showing the structure of an external gear pump 10 according to an embodiment of the present invention, and FIG. 3 is a plan view of the external gear pump 10. There is. Further, FIG. 1 shows a cross-sectional view taken along line 1-1 of FIG.

As shown in FIGS. 1 and 2, the external gear pump 10 is provided with a housing 16 composed of a housing body 12 and a lid portion 14 which are made of metal such as aluminum. The housing body 12 has an upper side in the height direction (arrow A in FIGS. 1 and 2).
A gear accommodating portion 18 is formed which is open at the end face (direction side). The gear accommodating portion 18 includes a driving gear accommodating portion 20 that is opened in a substantially circular shape in plan view. The drive gear accommodating portion 20 is
The inner diameter of the driving gear 34 is slightly larger than the outer diameter of the driving gear 34, which will be described later, and the driving gear 34 can be housed therein. On the other hand, the driven gear accommodating portion 22 is located at a position displaced to one side in the width direction of the housing body 12 (direction of arrow B in FIGS. 1 and 2) with respect to the driving gear accommodating portion 20.
Are formed. The driven gear accommodating portion 22 has an inner diameter substantially equal to that of the driving gear accommodating portion 20 described above, and is slightly larger than an outer diameter dimension of a driven gear 54 described later, and the driven gear 54 inside thereof. Can be accommodated.
A part of the driven gear accommodating portion 22 on the side of the driving gear accommodating portion 20 overlaps with the driving gear accommodating portion 20, and the driven gear 54 is meshed with the driving gear 54.
Can be housed inside the driven gear housing 22.

Further, as shown in FIGS. 1 to 3, a suction hole 24 as a suction portion is formed in the housing body 12. The suction hole 24 corresponds to the driving gear housing 2 described above.
From a substantially central portion of an imaginary line connecting the center of 0 and the center of the driven gear accommodating portion 22, one side (see FIG.
One end is open at the inner wall of the gear accommodating portion 18 (in the direction of arrow C) and the other end is open at the outer peripheral side portion of the housing body 12. When the external gear pump 10 is applied to, for example, a configuration of an electronically controlled hydraulic braking device for a vehicle, the suction hole 24 communicates with a brake oil reservoir (oil tank or the like).

On the other hand, from the substantially central portion of the above-mentioned virtual line,
On the other side of the imaginary line as a boundary (on the side opposite to the arrow C in FIG. 2), one end opens at the inner wall of the gear accommodating portion 18,
A discharge hole 26 is formed as a discharge portion, the other end of which is open at the outer peripheral side of the housing body 12. When the external gear pump 10 is applied to, for example, a configuration of an electronically controlled hydraulic braking device for a vehicle, the discharge hole 26 communicates with a cylinder or the like provided in a caliper or the like of the brake.

Further, as shown in FIGS. 1 and 2, a bearing hole 30 as a first bearing portion and a bearing hole 32 as a second bearing portion are formed in the bottom portion 28 of the gear accommodating portion 18. Has been done. The bearing hole 30 has one end opened at the suction hole 24 and the other end opened at the back surface of the housing body 12. The shaft center of the bearing hole 30 is substantially aligned with the center of the driving gear housing portion 20. On the other hand, the bearing hole 32 also has one end opened at the suction hole 24 and the other end opened at the rear surface of the housing body 12. Further, the bearing hole 32 is
The axis thereof is substantially coincident with the center of the driven gear accommodating portion 22.

As shown in FIGS. 1 to 3, in the driving gear housing portion 20 of the gear housing portion 18 having such a structure, the entire driving body is made of a metal harder than the material forming the housing body 12. The gear 34 is housed. The driving gear 34 has a plurality of outer teeth 36, and a gear body 40 having tooth spaces 38 between the outer teeth 36. A shaft 42 as a first shaft having a diameter smaller than that of the gear body 40 is coaxially extended from one end of the gear body 40 in the axial direction, and penetrates through the bearing hole 30 described above. Here, the outer diameter dimension of the shaft 42 is slightly smaller than the inner diameter dimension of the bearing hole 30. More specifically, the size of the gap formed between the inner peripheral portion of the bearing hole 30 and the outer peripheral portion of the shaft 42 when the shaft 42 is passed through the bearing hole 30 coaxially is determined by the size of the driving gear. When the gear body 40 is coaxially arranged with respect to the housing portion 20, the shaft 42 is smaller than the gap formed between the inner peripheral portion of the driving gear housing portion 20 and the outer teeth 36 of the gear body 40. The outer diameter dimension of is set. Further, a portion of the shaft 42 penetrating from the bearing hole 30 is connected to a driving means such as a motor (none of which is shown) via a mechanical motion transmitting means such as a gear, and indirectly drives the driving force of the driving means. The shaft 42, the shaft 42 rotates around its own axis to rotate the tooth groove 38. On the other hand, a shaft 44 having a diameter smaller than that of the gear body 40 is coaxially extended from the other axial end of the gear body 40 (that is, the end opposite to the side where the shaft 42 is formed). .

On the other end side of the gear body 40 in the axial direction,
A side plate 46 is arranged adjacent to the gear body 40. As shown in FIGS. 1 and 2, the side plate 46 includes a disk-shaped large-diameter portion 48 whose outer diameter dimension is slightly smaller than the inner diameter dimension of the driving gear accommodating portion 20. It is housed inside the gear housing portion 20. At the end of the large diameter portion 48 on the side opposite to the tooth groove 38 of the driving gear 34,
Small diameter part 5 whose outer diameter is smaller than that of the large diameter part 48
0 is formed. Here, as shown in FIG.
The central axis of the small diameter portion 50 is displaced toward the suction hole 24 side (the direction of arrow C in FIG. 4) with respect to the central axis of the large diameter portion 48. Further, the side plate 46 is formed with a through hole 52 penetrating along the axial direction of the large diameter portion 48 and the small diameter portion 50. The through hole 52 is coaxial with the large diameter portion 48, and the shaft 44 of the driving gear 34 is inserted therein. However, the inner diameter dimension of the through hole 52 is set to be sufficiently larger than the outer diameter dimension of the shaft 44, and when the driving gear 34 is housed in the driving gear housing portion 20, the outer peripheral portion of the shaft 44 is arranged. Does not come into contact with the inner peripheral portion of the through hole 52. Therefore, the shaft 44 is merely inserted into the through hole 52 and is not supported by the through hole 52.

On the other hand, as shown in FIGS. 2 and 3, the driven gear accommodating portion 22 forming the gear accommodating portion 18 together with the driving gear accommodating portion 20 is formed of a metal having a hardness substantially equal to that of the driving gear 34. The driven gear 54 is housed. The driven gear 54 has the same number of external teeth 56 as the driving gear 34, and includes a gear body 60 having a tooth groove 58 between each external tooth 56. From one end of the gear body 60 in the axial direction, a shaft 6 as a second shaft having a smaller diameter than the gear body 60 is provided.
2 extends coaxially and penetrates the bearing hole 32 described above. Here, the outer diameter dimension of the shaft 62 is slightly smaller than the inner diameter dimension of the bearing hole 32. More specifically, the size of the gap formed between the inner peripheral portion of the bearing hole 32 and the outer peripheral portion of the shaft 62 when the shaft 62 is passed through the bearing hole 32 coaxially is determined by the size of the driven gear. The shaft 62 is smaller than the gap formed between the inner peripheral portion of the driven gear housing portion 22 and the outer teeth 56 of the gear body 60 when the gear body 60 is coaxially arranged with respect to the housing portion 22. The outer diameter dimension of is set. On the other hand, a shaft 64 having a diameter smaller than that of the gear main body 60 is coaxially extended from the other axial end of the gear main body 60 (that is, the end opposite to the side where the shaft 62 is formed). .

On the other end side of the gear body 60 in the axial direction,
A side plate 66 is arranged adjacent to the gear body 60. As shown in FIG. 2, the side plate 66 includes a disk-shaped large-diameter portion 68 whose outer diameter dimension is slightly smaller than the inner diameter dimension of the driven gear accommodating portion 22, and together with the driven gear 54, the driven gear accommodating portion. It is housed inside 22. A small diameter portion 70 having an outer diameter dimension smaller than the outer diameter dimension of the large diameter portion 68 is formed at the end of the large diameter portion 68 of the driven gear 54 on the side opposite to the tooth groove 38. Here, as shown in FIG. 4, the small diameter portion 7
The central axis of 0 is the suction hole 24 with respect to the central axis of the large diameter portion 68.
To the side (the direction of arrow C in FIG. 4). Further, the side plate 66 is formed with a through hole 72 penetrating along the axial direction of the large diameter portion 68 and the small diameter portion 70. The through hole 72 is coaxial with the large diameter portion 68, and the shaft 64 of the driven gear 54 is inserted therein. However, the inner diameter dimension of the through hole 72 is set to be sufficiently larger than the outer diameter dimension of the shaft 64, and when the driven gear 54 is accommodated in the driven gear accommodating portion 22, the outer peripheral portion of the shaft 64 is accommodated. Does not come into contact with the inner peripheral portion of the through hole 72. Therefore, the shaft 64
Is simply inserted into the through hole 72,
Is not supported by.

Further, as shown in FIGS. 2 and 4,
A part of the outer circumference of the large diameter portion 48 of the side plate 46 described above is cut linearly in plan view corresponding to the portion where the driving gear housing portion 20 and the driven gear housing portion 22 overlap.
The cut portion 76 is cut linearly in a plan view corresponding to a portion where the driving gear accommodating portion 20 and the driven gear accommodating portion 22 overlap, also on a part of the outer periphery of the large diameter portion 68 of the side plate 66. Are formed. These cut parts 74, 76
The side plates 46 and 66 can be arranged in the gear accommodating portion 18 by making them face each other.

A pressure receiving portion 78 as a pressing force acting portion is formed on the large diameter portion 48 of the side plate 46. In the pressure receiving portion 78, with the side plate 46 arranged in the driving gear accommodating portion 20, a part of the outer peripheral portion of the large-diameter portion 48 facing the suction hole 24 side is part of the end on the small-diameter portion 50 side. It is formed by linearly cutting out from the portion to the axially intermediate portion of the side plate 46, and the surface thereof is formed by the large diameter portion 48 of the side plate 46 and the side plate 6.
The large-diameter portion 68 of No. 6 is substantially parallel to an imaginary line connecting the center lines of the large-diameter portions 68 and is directed to the suction hole 24 side.

On the other hand, the large diameter portion 68 of the side plate 66 is formed with a pressure receiving portion 80 as a pressing force acting portion. In the pressure receiving portion 80, with the side plate 66 arranged in the driving gear accommodating portion 20, a part of a portion of the outer peripheral portion of the large diameter portion 68 facing the suction hole 24 side is an end on the small diameter portion 50 side. It is formed by linearly cutting out from the portion to the axially intermediate portion of the side plate 66, and the surface thereof is formed by the large diameter portion 68 of the side plate 66 and the side plate 4.
6 is substantially parallel to an imaginary line connecting the center lines of the large diameter portions 48 and is directed toward the suction hole 24 side.

The small diameter portion 50 of each of the side plates 46, 66 described above,
70 penetrates a pair of through holes 82 (see FIG. 2) formed in the lid portion 14. The inner diameter dimension of each through hole 82 is larger than the outer diameter dimension of the small diameter portions 50 and 70, but is larger than the large diameter portions 48 and 6.
8 is smaller than the outer diameter dimension. Therefore, if the lid portion 14 is fixed to the housing body 12 by fastening means such as bolts, the side plates 46 and 66 will not fall out of the housing 16. An annular ring groove 84 is formed coaxially with each through hole 82 on the back surface of the lid portion 14 (the surface on the housing body 12 side). The inner diameter of these ring grooves 84 is larger than the inner diameter of the through hole 82, and an O-ring (O-ring) 86 formed in an annular shape by a rubber material or a flexible and elastically deformable synthetic resin material is arranged inside thereof. The O-ring 86 allows the through hole 82 and the small diameter portions 50, 70 to be formed.
The space between and is sealed.

Next, the operation and effect of this embodiment will be described.

The external gear pump 10 transmits the driving force of driving means such as a motor to the shaft 42 of the driving gear 34 by means of mechanical motion transmitting means such as gears, and when the shaft 42 is rotated around its own axis, the gears are rotated. The main body 40 rotates in the direction of arrow D in FIG.
The gear body 60 of the driven gear 54, in which the outer teeth 56 and the tooth grooves 58 mesh with the tooth grooves 38, rotates in the direction of arrow E in FIG.

At this time, the driving gear 34 and the driven gear 5 enter into the gear accommodating portion 18 through the suction hole 24.
The fluid such as oil and water contained in the tooth spaces 38 and 58 of No. 4 is caused by the rotation of the driving gear 34 and the driven gear 54.
While being accommodated in the 8, 58, it is conveyed in the rotation direction. The fluid in each tooth groove 38, 58 of the driving gear 34 and the driven gear 54 is conveyed to the discharge hole 26, and each tooth groove 38, 58 that has contained the fluid meshes with each outer tooth 36, 56. By starting each tooth groove 38, 5
The fluid in 8 is pushed out. Then, each tooth groove 38, 58
The outer teeth 36 and 56 completely mesh with each other, and the outer teeth 36 and the outer teeth 56 contact each other at this meshing portion, thereby sealing between the driving gear 34 and the driven gear 54. As a result, the fluid pushed out from the tooth spaces 38, 58 cannot return to the suction hole 24 side. Therefore, the driving gear 34
By rotating the driven gear 54 and the fluid in each tooth groove 38, 58 to the discharge hole 26 side one after another, the internal pressure on the discharge hole 26 side increases, and the fluid is discharged to the outside of the housing 16 through the discharge hole 26. To be done.

On the other hand, each external tooth 3 meshed with each tooth groove 38, 58 by the rotation of the driving gear 34 and the driven gear 54.
6 and 56 come out of the tooth spaces 38 and 58, the tooth spaces 3
A negative pressure corresponding to the volume of the meshing between the outer teeth 36 and 56 and the outer teeth 58 is generated on the suction hole 24 side, and the negative pressure sucks the fluid from the outside of the housing 16 through the suction hole 24. It

Further, as described above, when the internal pressure is improved on the discharge hole 26 side and the negative pressure is generated on the suction hole 24 side, the discharge hole 26 is formed.
The fluid on the side is the external teeth 3 of the driving gear 34 and the driven gear 54.
6, 56 and the tooth spaces 38, 58 are pressed toward the suction hole 24. Here, in the external gear pump 10, the driving gear 3
When the shaft 42 of No. 4 is coaxially inserted into the bearing hole 30, the gap formed between the shaft 42 and the bearing hole 30 is also the gear body 4 of the driving gear 34 in the driving gear housing 20.
It is slightly larger than the gap formed between the inner peripheral portion of the driving gear housing portion 20 and the tips of the outer teeth 36 of the driving gear 34 when 0 is accommodated coaxially. On the other hand, when the shaft 62 of the driven gear 54 is coaxially inserted into the bearing hole 32, the shaft 62
Similarly, the gap formed between the driven gear accommodating portion 22 and the bearing hole 32 is the same as the inner peripheral portion of the driven gear accommodating portion 22 and the driven gear 54 when the gear body 60 of the driven gear 54 is coaxially accommodated in the driven gear accommodating portion 22. It is slightly larger than the gap formed between the outer tooth 56 and the tip of the tooth. Further, as described above, the side plates 46, 6
The inner diameters of the through holes 52 and 72 of 6 are sufficiently larger than the outer diameters of the shafts 44 and 64 of the driving gear 34 and the driven gear 54, and the shafts 44 and 64 are simply inserted into the through holes 52 and 72. It's just Therefore, the discharge hole 26
The fluid on the side is the external teeth 3 of the driving gear 34 and the driven gear 54.
When 6, 56 and the tooth grooves 38, 58 are pressed toward the suction hole 24, the driving gear 34 and the driven gear 54 move in the pressing direction, and the shafts 42, 62 of the driving gear 34 and the driven gear 54 are sucked. The bearing holes 30, 32 are moved to the hole 24 side.
Of the driving gear accommodating portion 20 and the tips of the outer teeth 36 of the driving gear 34 come into contact with the inner peripheral portion of the driving gear housing portion 20 on the side of the suction hole 24, and are driven. Gear housing 2
The tooth tops of the outer teeth 56 of the driven gear 54 come into contact with the inner peripheral portion of the second suction hole 24 side. As a result, the communication between the suction hole 24 and the discharge hole 26 in the inner peripheral portions of the driving gear housing portion 20 and the driven gear housing portion 22 (that is, the gear housing portion 18) is completely blocked and sealed. Therefore, the fluid on the discharge hole 26 side does not leak to the suction hole 24 side due to the pressure difference, and the discharge efficiency is improved.

By the way, if it suffices to simply support the driving gear 34 and the driven gear 54 so as to be displaceable in the direction orthogonal to the axis thereof, the shaft 4 on the housing body 12 side.
Instead of supporting the shafts 62 and 62, the shafts 44 and 64 may be supported by the through holes 52 and 72 of the side plates 46 and 66 so as to be displaceable along the direction orthogonal to the axes.

However, when the shafts 44 and 64 are supported by the side plates 46 and 66, the driving gear 34
And the displaceable amount of the driven gear 54 along the axis orthogonal direction is
Outer diameters of the gear bodies 40, 60, inner diameters of the driving gear housing 20 and the driven gear housing 22, and through holes 52, 7
In addition to the inner diameter of 2, the outer diameter of the shafts 44 and 64,
It depends on the size of each part such as the outer diameter size of the large diameter parts 48 and 68, the inner diameter size of the through hole 82, and the like, and is affected by these tolerances. That is, the amount of movement of the gear bodies 40 and 60 until the tooth tips of the outer teeth 36 and 56 contact the inner peripheral portion of the gear accommodating portion 18, and the shafts 44 and 64 contact the inner peripheral portions of the through holes 52 and 72. In order to match the movement amounts of the shafts 44 and 64 until they come into contact with each other, it is necessary to strictly set the dimensional tolerances of the respective parts described above.

On the other hand, as in the present embodiment, the shaft 4 is formed by the bearing holes 30 and 32 in the bottom portion 28 of the gear accommodating portion 18.
In the case of supporting the two and 62, the driving gear 34
And the displaceable amount of the driven gear 54 along the axis orthogonal direction is
The outer diameter of the gear bodies 40 and 60, the inner diameter of each of the driving gear housing 20 and the driven gear housing 22, the bearing hole 30,
Since it depends only on the inner diameter dimension of 32 and the outer diameter dimension of the shafts 42 and 62, the tolerance can be relatively relaxed,
Manufacturing is easy.

On the other hand, the fluid sent to the discharge hole 26 side has an inner peripheral portion of the gear accommodating portion 18 on the discharge hole 26 side, the driving gear 34 and the driven gear 54 as the internal pressure on the discharge hole 26 side increases.
Through the gap between the gear bodies 40 and 60 of
Sent to the side. Further, the fluid that has passed through the gap between the inner peripheral portion of the gear accommodating portion 18 and the gear main bodies 40 and 60 is
6, 66 large diameter parts 48, 68 outer peripheral part and gear accommodating part 18
Through the gap between the large diameter portions 48, 68 and the surface of the large diameter portions 48, 68 on the side of the lid portion 14 and the lid portion 14, and the pressure causes the lid portions 14 of the large diameter portions 48, 68 to move. The side surface is the gear housing 18
It is pressed by the force of F ₁ toward the bottom portion 28 side of. The large diameter portions 48, 68 (side plates 46, 66) pressed by the fluid are driven by the driving gear 34.
The respective gear bodies 40 and 60 of the driven gear 54 are pressed toward the bottom portion 28 of the gear accommodating portion 18, whereby the driving gear 3
The gaps between the respective gear bodies 40 and 60 of the gear 4 and the driven gear 54 and the bottom portion 28 of the gear accommodating portion 18 are reduced or eliminated. Therefore, the leakage of fluid from the discharge hole 26 side to the suction hole 24 side is reduced or prevented through the gaps between the gear bodies 40 and 60 of the driving gear 34 and the driven gear 54 and the bottom portion 28 of the gear housing portion 18. It is possible (that is, the external gear pump 10 is a so-called pressure loading type external gear pump).

The fluid that has entered between the lid 14 and the surfaces of the large-diameter portions 48 and 68 on the lid 14 side is the large-diameter portion 4
The surfaces of the lids 8 and 68 on the side of the lid portion 14 are the bottom portions 28 of the gear housing portion 18.
The pressure receiving portion 7 of each side plate 46, 66
Press 8,80. Here, the pressure receiving portions 78 and 80 are
Since the surface is directed to the discharge hole 26 side, the pressing force F ₂ on the pressure receiving portions 78 and 80 is naturally directed to the suction hole 24 side. The side plates 46 and 66 that have received this pressing force F ₂ are displaced to the suction hole 24 side, and the outer peripheral portions of the large diameter portions 48 and 68 are located on the suction hole 24 side of the driving gear accommodating portion 20 and the driven gear accommodating portion 22. It is pressed against the inner circumference. Thereby, the large diameter portion 48,
Since the communication between the gap between the cover 68 and the lid 14 and the suction hole 24 is completely blocked and sealed, the fluid flowing from the gap between the large diameter portions 48, 68 and the cover 14 into the suction hole 24. Leakage can be reduced or prevented, and the ejection efficiency is improved.

The gap between the inner peripheral portions of the bearing holes 30 and 32 and the outer peripheral portions of the shafts 42 and 62 is defined by the tips of the outer teeth 36 and 56, the driving gear accommodating portion 20 and the driven gear. If it is larger than the gap between the inner peripheral portion of the accommodating portion 22 and the tooth tips of the outer teeth 36 and 56 contact the inner peripheral portions of the driving gear accommodating portion 20 and the driven gear accommodating portion 22, the bearing holes are not formed. Although it is conceivable that the outer peripheral portions of the shafts 42 and 62 do not come into contact with the inner peripheral portions of 30, 32, in the present external gear pump 10, the driving gear 34 and the driven gear 54 are constituted more than the material constituting the housing body 12. The material to be used is harder. Therefore, when the driving gear 34 and the driven gear 54 are rotated,
When the tips of the teeth 6, 6 are pressed against the inner peripheral portions of the driving gear accommodating portion 20 and the driven gear accommodating portion 22, the outer teeth 36, 56 are removed.
The tooth tops cut the inner peripheral portions of the driving gear accommodating portion 20 and the driven gear accommodating portion 22, and the driving gear 34 and the driven gear 54 move toward the suction hole 24 side by the cut amount. By continuing this, the shaft 4 is eventually moved to the inner peripheral portions of the bearing holes 30 and 32.
The outer peripheral portions of 2, 62 come into contact with each other, so that reliable shaft support is performed.

Further, in this embodiment, the side plates 46 and 76 are provided.
The centers of the small diameter parts 50 and 70 are displaced toward the suction hole 24 side with respect to the centers of the large diameter parts 48 and 68. Therefore, the surfaces of the large-diameter portions 48 and 68 on the side facing the lid portion 14 have the suction holes 2
It is wider on the discharge section 26 side than on the 4 side. Large diameter part 48, 6
The fluid that has entered between the lid 8 and the lid 8 is the large diameter portion 48, 6
If the size of the pressing force F ₁ for pressing 8 is the same in every portion, the total pressing force F ₁ becomes large on the side of the discharge portion 26 having a relatively large area. Therefore, the side plates 46 and 76 are connected to the driving gear 34 and the driven gear 54.
The pressing force pressing the gear toward the bottom portion 28 side of the gear accommodating portion 18 is larger on the discharge portion 26 side than on the suction portion 24 side. As described above, since the internal pressure is increased on the discharge portion 26 side, the fluid that has entered between the gear main bodies 40 and 60 of the driving gear 34 and the driven gear 54 and the bottom portion 28 of the gear accommodating portion 18,
The force for separating the gear bodies 40 and 60 from the bottom portion 28 of the gear accommodating portion 18 is larger on the discharge portion 26 side than on the suction portion 24 side. In the present external gear pump 10, as described above, the force pressing the gear bodies 40 and 60 against the bottom portion 28 on the discharge portion 26 side is larger than that on the suction portion 24 side, so that the discharge portion 26
Side of each gear body 40, 60 to the bottom 28 of the gear accommodating portion 18.
It can counter the force of pulling away from.

By the way, in the present embodiment, the pressure receiving portion 7
8 and 80 were planes parallel to the axial directions of the side plates 46 and 66, but as shown in FIG. 5, for example, as the pressure receiving portions 78 and 80 approach the small diameter portions 50 and 70, the diameter increases. It may be a flat surface or a curved surface intersecting (tilting) with respect to the axial direction of the side plates 46 and 66 so as to approach the centers of the portions 48 and 68. In the case of such a configuration, not only the above-described action is obtained and the same effect is obtained, but also the pressure receiving portion 7
There is also a possibility that formation of 8, 80 will be easy.

That is, when the large diameter portions 48 and 68 are cut to form the pressure receiving portions 78 and 80, the pressure receiving portions 78 and 8 are formed.
To make 0 a plane parallel to the axial direction of the side plates 46, 66, the gear bodies 40, 60 are cut along the direction orthogonal to the axial directions of the side plates 46, 66, and the side plates 46, 66 are
The gear bodies 40, 60 must be cut along the axial direction of (i.e., two cutting steps are required). However, when the pressure receiving portions 78, 80 are flat surfaces that intersect (incline) with the axial direction of the side plates 46, 66 so as to approach the centers of the large diameter portions 48, 68 as they approach the small diameter portions 50, 70 side. To do this, it is only necessary to cut along that direction (the cutting step is once). Therefore, the number of cutting steps is reduced, the pressure receiving portions 78 and 80 are easily formed, and the number of steps can be reduced, which contributes to cost reduction.

Further, in the present embodiment, the pressure receiving portion 7
8 and 80 are planes parallel to the line connecting the center of the large diameter portion 48 and the center of the large diameter portion 68 and facing the ejection hole 26 side, for example, as shown in FIGS. 6 and 7. In addition, the pressure receiving portions 78 and 80 may be flat surfaces that are inclined with respect to the discharge hole 26 side toward the outer side in the width direction of the housing 16.
In the case of such a configuration, the pressing force F ₂ received by the pressure receiving portions 78 and 80 is directed toward the suction hole 24 side and toward the center side in the width direction of the lid portion 14. Thereby, the side plate 46,
66 is not only pressed against the inner peripheral portion of the gear accommodating portion 18 on the suction hole 24 side, but the side plate 46 and the side plate 66 are pressed against each other to reduce the gap between the cut portion 74 and the cut portion 76, or Lost. Therefore, the cutting portion 7
Since the leakage of the fluid from the discharge hole 26 side to the suction hole 24 side through the gap between the nozzle 4 and the cut portion 76 can be reduced or prevented, the discharge efficiency is further improved.

[0041]

As described above, according to the present invention as set forth in claim 1, the first and second parts provided at the bottom of the gear accommodating portion.
Since the bearing portion supports the first and second shafts of the driving gear and the driven gear so as to be displaceable in the direction orthogonal to the axis, the tip of each gear is pressed against the inner peripheral portion of the gear accommodating portion by the internal pressure of the discharge portion. The discharge portion side and the suction portion can be reliably separated from each other, and the discharge efficiency can be improved.

The present invention according to claim 2 is the same as claim 1
Not only can the effects of the present invention described be obtained, but since the side plate can be pressed against the inner peripheral portion on the suction portion side of the gear accommodating portion by the pressure of the fluid that has entered the side opposite to each gear via the side plate, The fluid does not leak to the suction portion side through the side plate and the outer periphery of the side plate and the side opposite to each gear. Thereby, the ejection efficiency can be further improved.

[Brief description of drawings]

1 is a cross-sectional view of an external gear pump according to an embodiment of the present invention, which is a cross-sectional view taken along line 1-1 of FIG.

FIG. 2 is an exploded perspective view of the external gear pump according to the embodiment of the present invention.

FIG. 3 is a plan view of the external gear pump with a lid removed.

FIG. 4 is a plan view of a side plate.

FIG. 5 is a perspective view showing an example of another aspect of the side plate.

FIG. 6 is a perspective view showing an example of another aspect of the side plate.

FIG. 7 is a plan view showing an example of another aspect of the side plate.

[Explanation of symbols]

10 External gear pump 16 housing 20 Drive gear housing 22 Driven gear housing 24 Suction hole (suction part) 26 Discharge hole (Discharge part) 30 Bearing hole (first bearing part) 32 bearing hole (second bearing part) 34 Drive Gear 36 external teeth 42 shaft (first shaft) 46 Side plate 54 Driven gear 56 external teeth 62 shaft (second shaft) 66 side plate 78 Pressure receiving part (pressing force acting part) 80 Pressure receiving part (pressing force acting part)

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-9-287576 (JP, A) JP-A-6-17767 (JP, A) JP-A-11-132161 (JP, A) JP-A-55- 119990 (JP, A) JP-A-57-20580 (JP, A) Actually developed 57-112092 (JP, U) Actually developed 53-81908 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) F04C 2/18 321 F04C 2/18 311

Claims (2)

(57) [Claims] 1. When the first shaft is coaxially formed,
And driving gear external teeth rotated by the driving force around the first shaft, the driving gear together with the second shaft is coaxially formed
A driven gear having external teeth that rotate around the second shaft as the driving gear rotates, a driving gear housing portion that houses the driving gear, and a driven gear housing that houses the driven gear that meshes with the driving gear. with part are formed respectively, wherein the driving gear housing portion and the suction portion communicating with each of the driven gear housing portion and said driving gear and said driven gear and the suction unit via the engagement portion on the opposite side and a housings which discharge portion is formed that communicates with each of said driving gear accommodating portion and the driven gear accommodating portion, before the rotation of the driving gear and the driven gear
A circumscribing guide that sends the fluid sucked from the suction part to the discharge part side.
In the pump, the tooth tips of the outer teeth of the driving gear are the inner circumference of the driving gear accommodating portion.
The first shaft in the direction orthogonal to the axis until it abuts
The first bearing portion that is rotatably supported and the tips of the outer teeth of the driven gear are the inner circumference of the driven gear accommodating portion.
The second shaft in the direction orthogonal to the axis until it abuts
And a second bearing portion that supports the movable gear and the driven gear.
Negative pressure in the suction part caused by the rotation of the yarn and the discharge
Due to the increase of the internal pressure in the section, the driving gear and the driven gear are
The outer gear teeth of the driving gear to displace the driving gear.
The driven gear and the outer teeth of the driven gear.
An external gear pump , which is brought into contact with an inner peripheral portion of a dynamic gear housing portion . Wherein the first shaft and second shaft in towards the axial direction of the driving gear and the driven gear on the opposite side, provided with a side plate disposed adjacent to said driving gear and driven gear, said A discharge pressure introducing passage that communicates with the discharge portion and introduces the internal pressure of the discharge portion to the opposite side of the driving gear and the driven gear of the side plate is formed in the housing, and the side plate is formed through the discharge pressure introducing passage. In the side plate, a pressing force acting portion for pressing the side plate toward the suction part side by the discharge pressure introduced to the side opposite to the driving gear and the driven gear is provided in the side plate.
The side plate is accommodated in the driving gear by the discharge pressure received by the use part.
Pressed against the inner peripheral portion of the parts and the suction side of the sub driven gear accommodating portion
The external gear pump according to claim 1, wherein