JPH04101084A - External gear pump - Google Patents

Abstract

PURPOSE:To prevent the increase of axial load, bearing load, shaft power, and the like, and also the generation of cavitation by forming such structure as to press/energize slide valve plates to the opposite direction to the acting direction of liquid pressure, that is, in the direction of going away from the gear side faces, using liquid pressure acting upon the back face of the slide valve plates. CONSTITUTION:Two slide valve plates 12 each serving as bearing plates are mounted with slight gaps into chamber parts 3A, 3B between both side faces of a pair of gears 5, 7 and the end wall faces 11A, 11B, respectively opposed to both side faces, of an internal chamber 3. In each slide valve plate 12, a pair of circular pressure liquid through holes 12a, 12b opened opposedly to the side faces of the gears 5, 7 are provided in the axially symmetrical state on both sides of a vertical axis X passing the center of each bearing hole 12' of the slide valve plate 12. Ring protrusions 13 slightly protruding inward are also formed at the parts, corresponding to the respective gears 5, 7, of the respective end wall faces 11A, 11B so as to always leave slight space between the end wall faces 11A, 11B and the slide valve plates 12.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a gear pump in which a pair of gears mesh and rotate in a circumscribed manner within an internal chamber of a casing.

[Conventional technology]

A pair of gears mesh and rotate externally in an internal chamber of a casing, and each chamber portion between both side surfaces of the pair of gears and the end wall surface of the internal chamber facing each side is , a plurality of sliding valve plates serving as bearing members having shapes and dimensions that match the cross-sectional shape and dimensions of the chamber are loaded with a slight gap left, and gears are inserted into the bearing holes of these sliding valve plates. The drive shaft and the driven shaft of the casing, the pair of gears and the 3-4
(See Publication No. 6276).

[Problem to be solved by the invention]

In the above-mentioned known gift pump, a plurality of sliding valve plates slide axially under hydraulic pressure and function as pressure regulating valves, creating a harmful pressure difference between the discharge and suction sides of the pump. This makes it possible to prevent increases in shaft load, bearing load, shaft power, etc., and the occurrence of cavitation, while also making it possible to use it for general purposes in sucking up and pumping acidic liquids and various other liquids. This is what I did.

However, when the pump is operated at particularly high speeds in order to achieve high pump efficiency, sometimes high hydraulic pressure acts on the back surface of the sliding valve plate adjacent to the end wall surface of the pump casing, causing pressure to flow adjacent to the side surface of the gear. It has been discovered that the sliding valve plate is strongly pressed against the side surface of the gear to bring it into frictional contact, and the friction reduces pump efficiency and damages the gear.

The present invention can further enhance the above-mentioned effects of the known gear pump, and utilizes the hydraulic pressure acting on the back surface of the sliding valve plate to move the sliding valve plate in the direction opposite to the acting direction of the hydraulic pressure. In this way, the above-mentioned disadvantages can be solved and an improved external gear pump with better performance can be provided. This is what I did.

[Means to solve the problem]

In the gear pump of the present invention, in the above configuration, a plurality of sliding valve plates adjacent to side surfaces of the pair of gears, among the plurality of sliding valve plates, have a plurality of openings facing the side surfaces of each gear. Pressure liquid passage holes are provided axially symmetrically, and pressure liquid passage holes that can be aligned in the axial direction with the respective pressure liquid passage holes of the adjacent sliding valve plates are also provided on the other sliding valve plates, and When the sliding valve plate and the other sliding valve plate abut each other, the respective corresponding pressure fluid passage holes of each sliding valve plate are axially aligned with each other to form a plurality of linear pressure fluid supply passages. It is configured so that

For reasons to be described later, an annular protrusion slightly protruding inward is formed on each end wall surface of the casing internal chamber at a portion corresponding to each gear. It is a good idea to always leave some space between the valve plate and the valve plate.

[For production]

In the gear pump configured as described above, after the start of operation, the discharge pressure increases, and hydraulic pressure acts on the back surface of the sliding valve plate adjacent to each end wall surface of the internal chamber, causing it to slide. When the sliding valve plates are brought into contact with each other, the respective corresponding pressure fluid passage holes of each sliding valve plate are axially aligned with each other to form a plurality of linear pressure fluid supply passages. In this case, the sliding valve plate adjacent to the side surface of the gear is pressed against the side surface of the gear due to the pressure received from the back surface, but part of the pressure fluid acting on the back surface of the sliding valve plate on the end wall side is The pressure liquid is ejected toward the side surface of the gear through the supply passage, and the pressure of the ejected pressure liquid or liquid film acts to push the sliding valve plate back from the side surface of the gear, and the side surface of the gear on the adjacent sliding valve plate. to prevent crimping.

-i [Embodiment] Hereinafter, the present invention will be explained in detail with reference to the attached drawings showing an example of its implementation.6 In the first to third leaps, 1 is a casing of a vertically elongated external spar gear pump; The wall IA and the peripheral wall IB are integrally formed, and a bearing body 2 is connected to the open side IC of the casing with bolts and nuts.In the internal chamber 3 of the casing, which has a roughly figure-8 cross section, there is a drive shaft. The gear 5 on the fourth side and the gear 7 of the six driven wheels are disposed in a state of circumscribing and meshing vertically, and the drive shaft 4 is passed through the bearing body 2 and supported by the bearing 8 in a sealed state. There is. This drive shaft 4 is
When the gear 5.7 is rotated by an electric motor (not shown) connected to the shaft end projecting outwardly from the bearing body 2 and driven by the drive shaft 4, the suction port 9 of the casing 1 is rotated.
The liquid introduced into the internal chamber 3 is confined in the space formed by the inner wall surface of the peripheral wall IB and the valleys of the teeth, is pressurized, and is sent out from the discharge port 10.

In the illustrated example, both side surfaces of the pair of gears 5.7 described above and the end wall surface 1 of the internal chamber 3 facing each of these side surfaces are shown.
In the palm portions 3A and 3B between the palm portions 1A and IIB, two sliding valve plates 12 each serving as a bearing plate having a shape and dimensions that match the cross-sectional shape and dimensions of these palm portions are left with a slight gap. The sliding valve plates are each loaded in the following manner:
It has a pair of bearing holes 12' and 12', respectively, and by inserting both the drive shaft 4 of the gear 5 and the driven shaft 6 of the gear 7 into these bearing holes, they can be slid slightly in the axial direction. Each is supported. Of the two sliding valve plates 12.12, the sliding valve plate 12 adjacent to the side surface of the -pair gear 5.7 has an opening facing the side surface of each gear 5.7. Pairs of circular pressure fluid passage holes 12a, 12b are provided axially symmetrically on both sides of the longitudinal axis vAX passing through the centers of the bearing holes 12', 12' of the sliding valve plate 12, respectively. , the other sliding valve plate 1, that is, the sliding valve plate 1 adjacent to the end wall surface 11A, which is the inner wall surface of the end wall IA of the casing 1, and the end wall surface 11B, which is the inner wall surface of the bearing body 2, respectively.
2 also have respective pressure fluid passage holes 1 in the adjacent sliding valve plate 12 on the side surface of the gear.
2a and 12b, respectively, and a pressure liquid passage hole 1 that can be aligned in the axial direction.
2a and 12b are provided, respectively. Each sliding valve plate 1
As will be described later, when the sliding valve plates 12 come into contact with each other, the two corresponding pressure fluid passage holes 12a, 12b align with each other in the axial direction to form each pair of linear pressure fluid supply passages 12A, 12B
form.

Casing 1, bearing body 2, gear 5.7 and sliding valve plate 12
are all synthetic resins with excellent mechanical properties, chemical properties, thermal properties, etc., particularly excellent dimensional stability, and low water absorption, such as resins such as PClPBT, or these resins. The gear shaft 4.6 is made of a fiber-reinforced composite material with a matrix of carbon fiber and other fibers as a reinforcing material, and the gear shaft 4.6 is made of a corrosion-resistant metal or ceramic.

In the illustrated example, an annular protrusion 13 slightly protruding inward is formed at a portion of each end wall surface 11A, 11B corresponding to each gear 5.7, and each end wall surface 11A , IIB and the sliding valve plate 12 adjacent to the end wall surface.
The configuration is such that there is always some space left between the two.

That is, each of the annular protrusions 13 is a stop protrusion that defines the limit of sliding of the sliding valve plate 12 outward, in other words, in the direction away from the side surface of the gear. Even if it slides outward due to the action of hydraulic pressure, this protrusion 13
Therefore, each end wall surface 11A, JI
There is no contact with B, and there is always some space 14 between them.
It is designed to leave behind.

On the other hand, this also defines the limit of sliding of the sliding valve plate 12 adjacent to the gear side surface in the direction away from the gear side surface, and the sliding limit is the sliding limit between the gear side surface and the adjacent sliding portion. This defines the maximum gap 15 between the valve plate 12 and the valve plate 12 (see Figure 2). Therefore, when designing the pump, consider the case where this gap becomes maximum due to the sliding of the sliding valve plate 12. In order to prevent an increase in liquid leakage, which may cause a decrease in discharge pressure and discharge amount, the gear 5.6 is loaded between one side of the gear 5.6 and the opposing end wall surface 11A, or the protrusion 13 of IIB. The total value of the gap to be left between the plurality of sliding valve plates 12, that is, the allowable sliding range of each sliding valve plate should be appropriately set according to the application of the pump and the like.

In the invention configured as described above, when the gears 5.7 are rotationally driven by the drive shaft 4, liquid is sucked into the internal chamber 3 from the suction port 9 as the gears 5.7 mesh with each other, and the liquid is sucked between the teeth. The confined liquid will be compressed and expanded due to changes in the confined volume, and the negative part of the compressed and pressurized liquid will be absorbed into the gap between the side surface of the gear and the adjacent sliding valve plate 12. 15 and the pressure liquid passage holes 12a, 12b of the sliding valve plate 12, the liquid is forced to flow into the palm portions 3A, 3B communicating with the suction side and the discharge side and escape, so that a large pressure change is prevented. can be prevented and the harm of confinement can be avoided. When the discharge pressure increases due to the continuous rotation of the gear 5.7, a part of the pressure liquid on the discharge side is transferred to the gear 5.7.
The sliding valve plate 12 adjacent to the gear is pressed in a direction away from the side surface of the gear, and the valve slides and flows into the suction side, so a relative rapid drop in pressure on the suction side is prevented by the action of this discharge pressure. This prevents harmful pressure differences between the discharge and suction sides. Therefore, this greatly reduces the lateral thrust that acts around the gear from the discharge side to the suction side, so even if the discharge pressure increases, the shaft load or bearing load will not increase proportionally. .

Next, as the discharge pressure increases, the pressure liquid flows into the gaps between each sliding valve plate 12 and the inner wall surface of the peripheral wall IB, and each sliding valve plate 12
The above-described space 1 is
4, and the pressure flows into each sliding valve! 12 in a direction away from the side of the gear, the pressure acts entirely on the back of the sliding valve plate 12 adjacent to the end wall surfaces 11A and IIB, pushing it toward the side of the gear. Slide it in the direction that approaches it. When the sliding valve plates 12 come into contact with each other due to this sliding, the corresponding pressure liquid passage holes 12a and 12b of each sliding valve plate 12 are aligned in the axial direction with each other, and a plurality of linear pressure liquids are formed. Supply passages 16A and 16B are formed. In this case, the sliding valve plate 12 adjacent to the side surface of the gear is forced to approach the side surface of the gear due to the pressing force applied to its back surface, but an action is applied to the rear surface of the sliding valve plate 12 on the side of the end wall surfaces 11A and IIB. A part of the pressure fluid is ejected toward the side surface of the gear through the pressure fluid supply passages 16A and 16B,
The rebound pressure of the ejected pressure liquid and the liquid film pressure present in the gap 15 act to push the sliding valve plate 12 away from the side surface of the gear, and push the adjacent sliding valve plate toward the side surface of the gear. Prevents crimping or frictional contact. In this case, pressure fluid passage 1
As mentioned above, 2a and 12b are the axis X of the sliding valve plate 12.
Since the pressure liquid is arranged axially symmetrically on both sides of the pressure liquid supply passages 16A and 16B, the pressure liquid ejected from each opening of the pressure liquid supply passages 16A and 16B pushes back the sliding valve plate 12 from the side surface of the gear. Since it acts not only on one side of llX but almost equally on both the left and right sides thereof, the sliding valve plate 12 can be smoothly slid almost linearly without swinging around its axis.
Contact with gears due to rocking is prevented. The amount of sliding in this case depends on the strength of the hydraulic pressure, but the strength of the hydraulic pressure can be greatly influenced by the diameters and shapes of the pressure fluid passage holes 12a and 12b of the sliding valve plate 12. It has been proven by experiment.

In the illustrated example, the thickness of the sliding valve plate 12 is approximately 311 mm.
m, the diameter of each circular portion is approximately 22.7+am, the diameter of each bearing hole 12' is approximately 611 IN, the diameter of the pressure fluid passage holes 12a, 12b is approximately 21 IN, and these through holes 12a, 12b are connected to the shaft m.
An axis Y and an axis X that are perpendicular to x and pass through the center of each bearing hole 12'
- Y intersects with the circular locus of the radius 51, and the circular locus is smaller than the diameter of the root circle of the gear 5.7 and the inner diameter of the annular projection 13. (See Figures 1 to 5). Then, the sliding valve plate 1 on the end wall surfaces 11A and 11B side
2 is in contact with the annular protrusion 13, the space 14 between the end wall surface and the sliding valve plate is approximately 0.2 mm, and in this state, the sliding valve plate 12 on the gear side The clearance on the side surface of the gear when it comes into contact with the gear is approximately 0.17
mm to 0.26+u+. And again, this gap 15
becomes smaller as the sliding valve plate 12 slides closer to the side surface of the gear due to back pressure, but does not become O due to the rebound pressure of the ejected pressure liquid or the action of the liquid film pressure, and under normal conditions The distance is approximately 0.1 to 0.2 mm, so that the gear-side sliding valve plate 12 does not come into frictional contact with the side surface of the gear (see FIG. 3).

〔Effect of the invention〕

Since the present invention is constructed like soft soil, it has the following effects.

According to the configuration described in the preamble of claim 1, the plurality of sliding valve plates are slid in the axial direction by hydraulic pressure and function as pressure regulating valves, thereby preventing harmful substances between the discharge side and the suction side of the pump. This prevents pressure differences from occurring, thereby preventing increases in shaft load, bearing load, shaft power, etc., and cavitation. Suppose that a plurality of pressure fluid passage holes opening facing the side surfaces of each gear are provided axially symmetrically, and the other sliding valve plates are also provided with each pressure fluid passage hole of the adjacent sliding valve plate. By providing pressure liquid passage holes that can be aligned in the axial direction, the discharge side and the suction side can be communicated more effectively, so that the above-mentioned effects are further enhanced.

By adopting the configuration described in the feature of claim 1, the sliding valve plate is moved in the opposite direction to the acting direction of the hydraulic pressure by using the hydraulic pressure acting on the back surface of the sliding valve plate, that is, It is possible to automatically maintain balance by pressing away from the side of the gear, so when operating the pump at high speed, hydraulic pressure acts on the back of the sliding valve plate adjacent to the end wall of the pump casing. Even if the sliding valve plate is adjacent to the side surface of the gear, it is brought into frictional contact with the side surface of the gear, and the disadvantages of reducing pump efficiency and damaging the gear due to the friction can be solved.

Further, in the second and third aspects, particularly in the third aspect, the adjacent sliding valve plate is prevented from coming into close contact with the end wall surface,
This makes it easier to apply hydraulic pressure to the back surface of the sliding valve plate, and conversely, it also prevents the sliding valve plate adjacent to the side surface of the gear from sliding in the direction away from the side surface of the gear, and therefore also prevents the gap between the two from opening. can be effectively regulated.

[Brief explanation of drawings]

FIG. 1 is a plan view that crosses the casing and bearing body of the gear pump according to the present invention and shows its internal structure, and FIGS. 2 and 3 are cross-sectional views of the casing and show the sliding state of the sliding valve plate. 4 is a longitudinal sectional view taken along the line AA' in FIG. 2, and FIG. 5 is an end view of the sliding valve plate. In the drawings, 1 is a casing, 3 is an internal chamber, 3A and 3B are chamber bones, 4 is a drive shaft, 5 is a drive gear, 6 is a driven shaft, 7 is a driven gear, IIA and 11B are end wall surfaces of the internal chamber,
12 is a sliding valve plate that also serves as a bearing member, 121 is a bearing hole, 1
2a and 12b are pressure fluid passages, 12A and 12B are pressure fluid supply passages, 13 is an annular projection, 14 is a space, and 15 is a gap on the side surface of the gear. Patent applicant Kazuo Shigeru

Claims (3)

[Claims] (1) A gear pump in which a pair of gears mesh and rotate externally in an internal chamber of a casing, and each side between both side surfaces of the pair of gears and an end wall surface of the internal chamber that faces each side of the pair of gears. A plurality of sliding valve plates serving as bearing members having shapes and dimensions matching the cross-sectional shape and dimensions of the chamber portion are loaded into the chamber portion with a slight gap left, and bearings of these sliding valve plates are loaded. Both the drive shaft and the driven shaft of the gear are inserted into the holes, and the casing, the pair of gears, and the sliding valve plate are each made of a synthetic resin material with good wear resistance, chemical resistance, etc. Of the plurality of sliding valve plates, a plurality of pressure fluid passage holes opening opposite to the side surfaces of each gear are provided axially symmetrically in the sliding valve plate adjacent to the side surfaces of the pair of gears. At the same time, other sliding valve plates are also provided with pressure fluid passage holes that can be aligned in the axial direction with the respective pressure fluid passage holes of the adjacent sliding valve plate, so that the adjacent sliding valve plates and the other sliding valves are connected to each other. When the plates come into contact with each other, the corresponding pressure fluid passage holes of each sliding valve plate align with each other in the axial direction, forming a plurality of linear pressure fluid supply passages. gear pump. (2) Protrusions that protrude slightly inward are formed at portions of each end wall surface of the casing internal chamber corresponding to each gear, respectively, and between each end wall surface and the sliding valve plate adjacent to the end wall surface. The gear pump according to claim 1, characterized in that the gear pump is configured to always leave some space. (3) The gear pump according to claim 2, wherein each projection is formed as an annular projection.