JP3612393B2 - Gear pump - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a gear pump that performs pumping action by rotation of a pair of gears that mesh with each other.
[0002]
[Prior art and problems to be solved by the invention]
Conventionally, a gear pump has been used in various industrial fields as a small and light pump having a simple structure.
As a structure of this type of gear pump, a pair of side plates are fitted into a cavity inside a housing to define a gear chamber, and a pair of gears meshing with each other are accommodated inside the gear chamber, and a support shaft of each gear is accommodated. A type in which a working fluid suction chamber and a discharge chamber are formed inside the gear chamber with the meshing positions of both gears interposed therebetween is generally supported by support holes formed in the side plates.
[0003]
On the other hand, in recent years, there has been a demand for a high-pressure type gear pump, but as the pressure increases, the support shaft is pushed in one direction in the support hole and becomes eccentric, so that wear of the portion supporting the support shaft is promoted. There is a problem that the pump efficiency decreases.
Conventionally, in order to lubricate the inside of the support hole, there has been a gear pump in which a spiral groove is provided in the support shaft or the support hole so that oil is forced into the support hole as the support shaft rotates (for example, actual (See Kaihei 4-105985). However, this gear pump has a problem that when the pump speed is low, the amount of oil supplied to the support hole is small and lubrication is insufficient even when the pump load is large (pressure on the discharge chamber side is high). .
[0004]
By the way, in the meshing portion of the gear, oil is confined in a closed region formed by each gear tooth meshing with each side plate (so-called confinement phenomenon occurs), and the confined oil is accompanied by the rotation of the gear. As a result of generating a very high pressure when compressed, there is a problem that vibration and noise are generated.
Therefore, a pair of clearance grooves that are spaced apart from each other with the meshing center position of both gears is formed on the side surface of the gear side of the side plate so that the high pressure generated at the meshing portion by each clearance groove is released to the suction chamber side and the discharge chamber side. A gear pump is provided (see, for example, Japanese Patent Laid-Open No. 48-17109). However, in this gear pump, since there is a limit to the area where each relief groove is provided, it is difficult to completely prevent the vicinity of the meshing center position.
[0005]
SUMMARY OF THE INVENTION An object of the present invention is to provide a gear pump that can prevent vibration and noise caused by closing near the gear meshing center position and can prevent wear of a portion that supports a gear support shaft, and has excellent durability. It is to be.
[0006]
[Means for Solving the Problems]
In order to solve the above problems, a gear pump according to claim 1 of the present invention defines a gear chamber by fitting a pair of side plates into a cavity inside a housing, and accommodates a pair of gears that mesh with each other inside the gear chamber. A gear pump in which a support shaft of each gear is fitted and supported by a support hole formed in each side plate, and a working fluid suction chamber and a discharge chamber are formed inside the gear chamber with a meshing position of both gears interposed therebetween. The side plate is formed with a flow path communicating the closed region formed by both side plates and the gear teeth engaged with the support hole and the support hole, and the flow path is an eccentricity of the inner peripheral surface of each support hole. It is characterized by opening in the side fitting region .
[0007]
In this configuration, the high-pressure working fluid that is to be confined in the vicinity of the meshing center position of both gears is guided to the fitting gap between the support shaft and the support hole via the flow path, and performs a lubricating action. Since the fluid is led from a portion that generates a high pressure regardless of the pump rotation speed, the fluid can be supplied for lubrication even when the pump rotation speed is low, and wear can be prevented. In addition, since the confining pressure in the vicinity of the meshing center position of both gears can be released, the occurrence of vibration and noise due to this can be prevented.
[0008]
The upper Kiryuro, since open to the eccentric-side fitting region of each support hole, there are the following advantages. In other words, the higher the pressure in the discharge chamber, the stronger the force that pushes the support shaft from the discharge chamber side toward the suction chamber side. Therefore, the support shaft is eccentric with respect to the support hole so that the support shaft approaches the suction chamber side. There is a tendency that the gap in the eccentric side fitting region of the inner peripheral surface of the hole is narrowed, which is a severe condition in terms of lubrication. On the other hand, in the present invention, since the fluid can be supplied to the side that is severe under high pressure in this way, it is more effective in preventing wear.
The “eccentric side” of the above-mentioned eccentric side fitting region corresponds to the “suction chamber side”, and the eccentric side fitting region is the suction on the inner peripheral surface of the support hole rather than the plane including the shaft centers of both support holes. This is a fitting region on the “suction chamber side” located on the chamber side.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Preferred embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a sectional view of a gear pump according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II in FIG. Referring to these drawings, the present gear pump closes both sides of a main body cylinder 10 having an oval cross-sectional cavity penetrating through the central portion thereof by a pair of cover plates 11 screwed so as to cover the entire surface thereof. The housing 1 comprised by this is provided. Inside the housing 1, a gear chamber 14 is defined between a pair of side plates 12 made of, for example, aluminum alloy, which are fitted from both sides of the hollow portion, and in the gear chamber 14, A drive gear 3 and a driven gear 4 that are paired with each other are arranged. An O-ring 13 is interposed between the lid plate 11 and the side plate 12 to seal the gear chamber 14.
[0010]
Inside the gear chamber 14, a pair of support shafts 30, 40 that are both supported by the support holes 31, 41 formed in a pair on each side plate 12, respectively, have an oval cross section. They are located on the axial centers of the semicircular portions on both sides, and are installed in parallel with each other.
One support shaft 30 supported by the pair of support holes 31 extends through the one cover plate 11 to the outside, and is rotated by a driving force from a power source such as a motor (not shown) transmitted to the extended end. A drive shaft to be driven is configured. The drive gear 3 is mounted on the support shaft 30 so as to be integrally rotatable inside the gear chamber 14. An oil seal 17 is disposed at a portion where the support shaft 30 penetrates the cover plate 11.
[0011]
The other support shaft 40 supported by the pair of support holes 41 constitutes a driven shaft having a shaft end in the support hole 41 of each side plate 12. The driven gear 4 is attached to the support shaft 40 inside the gear chamber 14. When the driven gear 4 is mounted on the support shaft 40, the rotation around the axis may be restricted or the rotation around the axis may be allowed. The driven gear 4 meshes with the drive gear 3 in a plane including the shaft centers of both the support shafts 30 and 40, and with the support shaft 40 (or the support shaft 40) along with the rotation of the drive gear 3 driven by the support shaft 30. It is designed to follow and rotate (without rotation).
[0012]
In FIG. 2, the rotation direction of the drive gear 3 and the driven gear 4 interlocked therewith is indicated by an arrow, and on both sides of the meshing position of both the gears 3, 4, the suction port chamber is located on the rotation direction side. 5, a discharge chamber 6 is formed on the counter-rotation direction side. The suction chamber 5 and the discharge chamber 6 are respectively connected to a suction destination and a discharge destination (not shown) outside the housing 1 via a suction port 15 and a discharge port 16 that open to corresponding positions of the main body cylinder 10. .
[0013]
With such a configuration, the working fluid introduced into the suction chamber 5 through the suction port 15 is received between the teeth of the drive gear 3 and the driven gear 4 facing the suction chamber 5, and the two gears 3, 4 rotate. Then, it is conveyed in a state of being sealed between the inner peripheral surface of the main body cylinder 10 between the respective teeth, and is sent out to the discharge chamber 6. The drive gear 3 and the driven gear 4 that have finished sending out to the discharge chamber 6 are directed toward the suction chamber 5 through the meshing positions of the two gears 3 and 4, and receive the working fluid in the suction chamber 5 again to discharge the discharge chamber. Acts to send to 6 side.
[0014]
During the operation of the gear pump performed as described above, inside the gear chamber 14, the low pressure inside the suction chamber 5 rises with the rotation of the drive gear 3 and the driven gear 4 and reaches the high pressure inside the discharge chamber 6. A pressure distribution is generated, and a pressing force in a direction indicated by a black arrow in FIG. 2 acts on the drive gear 3 and the driven gear 4. As a result, the support shafts 30 and 40 of the drive gear 3 and the driven gear 4 are pressed against the inner peripheral surfaces of the support holes 31 and 41 of the side plates 12 on the suction chamber 5 side to support the support shafts 30 and 40. It will contact via the oil film between the inner peripheral surfaces of the holes 31 and 41, and the frictional resistance at this contact portion will increase especially under low rotation when the oil film is not well formed, and the support hole There is a tendency to promote wear on the inner surface of 3,41. On the other hand, in the meshing part of the driving gear 3 and the driven gear 4, the working fluid is confined between the convex part of one tooth and the concave part of the other tooth, generating a very high pressure and generating vibration and noise. There is a fear.
[0015]
In the present embodiment, the high pressure in the region including the meshing center position K (see FIG. 2) of both the gears 3 and 4 into the support holes 31 and 41 of the side plate 12 that supports the support shafts 30 and 40 of both the gears 3 and 4. By providing an oil passage for guiding the working fluid, the lubrication in the support holes 31 and 41 is improved and the confinement is prevented, and the above-described problems are solved. FIG. 3 is a side view of the side plate 12, and FIG. 4 is a longitudinal sectional view of the side plate.
[0016]
Referring to FIGS. 3 and 4, annular grooves 61 and 62 are formed on the gear side surface 12 a of the side plate 12 so as to surround the support holes 31 and 41, respectively. The gear side surface 12a is formed with a relief groove 63 extending from the meshing position of both gears 3 and 4 to the suction chamber 5 side and a relief groove 64 extending to the discharge chamber 6 side. These escape grooves 63 and 64 prevent the occurrence of so-called confinement in which fluid is confined in a closed region formed by each side plate 12 and each meshing gear tooth at the meshing position of both gears 3 and 4. Is.
[0017]
Both escape grooves 63, 64 are provided so as to avoid the meshing center position K of both gears 3, 4, and a predetermined distance is secured between them. This is for preventing both the escape grooves 63 and 64 from communicating with each other because the suction chamber 5 and the discharge chamber 6 are communicated with each other through the escape grooves 63 and 64 and cannot perform the pump function. Note that the separation distance between the clearance grooves 63 and 64 that are separated from each other with the meshing center position K of both the gears 3 and 4 is as small as possible in consideration of the dimensional accuracy of each part, the meshing error of both the gears 3 and 4, and the like. It is set to be.
[0018]
In the gear side surface 12a of the side plate 12, the closed region including the meshing center position K of the gears 3 and 4 at the intermediate position (for example, the central position) between the clearance grooves 63 and 64, For example, a conical recess 81 is formed corresponding to a region isolated from the escape grooves 63 and 64, and channels 82 and 83 are formed to communicate the recess 81 with the support holes 31 and 41, respectively. Each of the flow paths 82 and 83 is formed from an eccentric side fitting region P of the inner peripheral surfaces 31a and 41a of the support holes 31 and 41 (in FIG. 3, a virtual plane 73 including the axes 71 and 72 of the support holes 31 and 41). Are also located on the suction chamber 5 side, which are portions of the inner peripheral surfaces 31a and 41a of the support holes 31 and 41).
[0019]
Reference numeral 65 denotes an escape groove for communicating the annular grooves 61 and 62 corresponding to the eccentric fitting region P of the inner peripheral surfaces 31a and 41a of the support holes 31 and 41 with the suction chamber 5 side. A similar relief groove 65 is also provided on the non-gear side surface 12 b of the side plate 12 so as to correspond to the support holes 31 and 41. Reference numeral 66 denotes an annular groove for accommodating the O-ring 13.
[0020]
The high-pressure working fluid that is to be confined in the closed region near the meshing center position K of both the gears 3 and 4 passes through the flow paths 82 and 83 and is fitted to the inner peripheral surfaces 31a and 41a of the support holes 31 and 41 on the eccentric side. It can be supplied to the joint area P. Further, the flow paths 82 and 83 are opened at a substantially central position in the axial direction within the support hole 31, and the working fluid supplied to this portion flows uniformly on both sides in the axial direction to support the support holes 31 and 41. After the whole is lubricated evenly, it is recovered to the suction chamber 5 side via the escape groove 65.
[0021]
According to the present embodiment, the high pressure generated in the closed region between the meshing teeth of the drive gear 3 and the driven gear 4 that could not be prevented by the conventional clearance grooves 63 and 64 that are separated from each other is suppressed, and vibration and Noise can be prevented. The combination of the conventional relief grooves 63 and 64 and the flow passages 82 and 83 that characterize the present embodiment can reliably prevent generation of high pressure due to confinement. In addition, since the high-pressure working fluid that is to be confined in the closed region can be supplied into the support shaft holes 31, 41, the inside of the support holes 31, 41 can be lubricated to prevent the occurrence of wear.
[0022]
Further, since the fluid for lubrication is supplied to the eccentric fitting region P of the support holes 31 and 41, which tends to be narrower between the support shafts 30 and 40 at high pressure, the wear prevention is further effective. .
In addition, this invention is not limited to the said embodiment, A various change can be given in the range of this invention.
[0023]
【The invention's effect】
According to the first aspect of the present invention, it is possible to prevent vibration and noise caused by confinement in the closed region formed by the gear teeth meshing with both side plates, and the high-pressure working fluid in the closed region is allowed to flow into the support shaft hole. As a result, the inside of the support hole can be lubricated to prevent wear.
[0024]
Also, there tends to be narrowed between the support shaft to the high pressure time, since the supply of fluid to the portion of the support hole, it is possible to some more effective prevention wear.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a gear pump according to an embodiment of the present invention.
2 is a cross-sectional view taken along line II-II in FIG. 1, and hatching is omitted.
FIG. 3 is a side view of a side plate.
FIG. 4 is a cross-sectional view of a side plate.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Housing 3 Drive gear 4 Driven gear 5 Suction chamber 6 Discharge chamber 12 Side plate 14 Gear chamber 30, 40 Support shaft 31,41 Support hole 31a, 41a Inner peripheral surface 82,83 Flow path K Engagement center position P Eccentric side fitting region

Claims (1)

A pair of side plates are fitted into the cavity inside the housing to divide the gear chamber, and a pair of gears meshing with each other are accommodated in the inside of the gear chamber. In the gear pump in which a suction chamber and a discharge chamber for the working fluid are formed inside the gear chamber with the meshing position of both gears interposed therebetween,
Formed in the side plate is a flow path that connects the support hole and a closed region formed by both side plates and the gear teeth engaged with each side plate ,
The said flow path is opening to the eccentric side fitting area | region of the internal peripheral surface of each support hole, The gear pump characterized by the above-mentioned .

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