JPH0861250A - Gear pump and method for running-in of said gear pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the life and efficiency of a gear pump and lower the manufactureing accuracy by forming an addendum gap capable of being changed in response to the pressure characteristics when the gear pump is operated, between the addendums of the gears and a pump casing of the gear pump. SOLUTION: Springly-elastic addendum circle walls 26 for gears 14, 16 are provided in a pump casing 12. The addendum circle walls 26 are set to be radially moved, and are positioned outside the addendum circle surface defined by addendums 28 to be extended outside the gears 14, 16 in circular arc ranges about 90 degrees from the suction side of a gear pump 10. The delivery side ends 30 of the addendum circle walls 26 can be freely radially moved, and the suction sides are integrally made with the pump casing 12 not to be axially moved. Liquid conveyed by the gear pump 10 enters a pressure chamber 32 to press the addendum circle walls 26 inwardly in the radial direction. Thus, when the pressure difference between the delivery side and the suction side is increased, the addendum gaps become narrower.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump having a pump casing having one suction connection and one discharge connection, the pump casing surrounding two meshing gears. One gear is non-rotatably arranged on the drive shaft which is rotatably supported by the pump casing and projects from the pump casing, and the other gear is on the idle shaft which is rotatably supported by the pump casing. Related to the ones that are located in.

[0002]

2. Description of the Related Art In order to achieve high efficiency, it is necessary to keep the amount of leakage, which means that the liquid in the pump flows back toward the suction side, as small as possible. This requires that the gap between the gear and the pump casing be kept small, and this gap may only allow a slight increase over the entire life of the gear pump. As a precondition for this, extremely high manufacturing accuracy that maintains strict tolerances is required, which inevitably increases the manufacturing cost.

[0003]

The advantage of the gear pump of the present invention is that it has a tooth gap that can be changed between the tooth tips of the gears of the gear pump and the pump casing in accordance with the pressure characteristics when operating the gear pump. The point is that they are doing. In that case, the lubrication gap always exists between the addendum and the pump casing. The adjustment of the tooth gap is performed over the entire life of the gear pump to extend the life of the gear pump. Leakage is minimal. Since the manufacturing accuracy of the present invention is low and a large tolerance is allowed, the manufacturing cost of the gear pump of the present invention can be reduced.

Further, the gear of the gear pump is pressed against the suction side based on the pressure difference between the discharge side and the suction side. Therefore, the tooth gap on the suction side becomes extremely small, and the tooth gap on the discharge side of the gear pump becomes large. Therefore, the pressure increase in the intermediate chamber of the gear teeth is sufficiently carried out in the suction-side region and only slightly in the discharge-side region. This causes a large pressure difference between the intermediate chambers of adjacent teeth in the suction-side region, which in turn increases the leakage flow. By disposing the tooth tip circular wall of the present invention that is movable in the radial direction in the discharge side region, the tooth gap in the gear pump of the present invention can be kept small even in the discharge side region of the gear. As a result, the addendum circle gap becomes narrower over the entire outer circumference of the gear that is transporting the liquid, so that the pressure is increased over the entire outer circumference of the gear that is transporting the liquid. The pressure difference between the intermediate chambers of adjacent teeth is small. Therefore, the leakage amount is reduced.

According to an advantageous method of the invention for running-in, the gear pump of the invention is operated in such a way that it does not or only slightly increases the pressure, while the pressure chamber is regulated. Loaded with liquid under possible pressure. This causes the elastic tip circular wall to be pressed radially inwardly towards the tip of the gear wheel, so that the tip and the inner surface of the tip circular wall are ground relative to each other. The familiar run operation can be acted upon by adjusting the liquid pressure to achieve the desired tip circle gap.

Claims 2 and onward describe advantageous further developments of the invention.

[0007]

Two embodiments of the invention are schematically illustrated in the drawings and will now be described in detail.

FIG. 1 shows a gear pump of the present invention, generally designated by the numeral 10, which pump casing 12 receives two gears 14,16.
have. The gear wheel 14 shown on the right side in FIG. 1 is arranged on a drive shaft 18 and is fixedly connected to the drive shaft 18 by means of a feather key 20.

The gear 14 meshes with a gear 16 shown on the left side of FIG. 1, which gear 16 is arranged on a floating shaft 22.

The pump casing 12 is closed by a rear casing cover 24 and a front casing cover not shown in FIG. Both shafts 18, 22
Are rotatably supported by the respective casing covers 24. The drive shaft 18 penetrates through one of the casing covers 24 and projects outward.

By rotationally driving the drive shaft 18, the gear 14 seated on the drive shaft 18 is rotated.
This gear 14 is another gear 1 meshing with the gear 14.
Drive 6 In the following description, consider that the rotation is performed in the direction of arrow f. The liquid to be transported is transported from the suction side located in the lower side in FIG. 1 to the discharge side located in the upper side in FIG. The liquid suction and outflow directions are indicated by arrows p in FIG.

The pump casing 12 has a spring-resilient tip circular wall 26 for each of the two gears.
Is movable in the radial direction. The tooth tip circular wall 26 is the tooth tip 2
Is located outside the tip circle defined by 8
From the suction side of the gear pump 10, it extends outside the gears 14, 16 by an arc section of approximately 90 °. The discharge-side end 30 of the addendum circular wall 26 is free to move in the radial direction, and the addendum circular wall 26 is integrally transferred to the pump casing 12 on the suction side. The tooth tip circular wall 26 is for both casing covers 2
It is immovable in the axial direction because it is guided during the period 4.

One pressure chamber 32 is located outside the tip circular wall 26, and the pressure chamber 32 opens inside the pump casing 12 at the discharge end 30 of the tip circular wall 26. ing. Through this opening 34, the gear pump 10
The liquid conveyed by reaches the pressure chamber 32. Since the pressure of the liquid in the intermediate chamber of the tooth rises when it is conveyed, the pressure of the liquid in the pressure chamber 32 that externally loads the tip circular wall 26 causes the pressure of the liquid acting inside the tip circular wall 26. Larger than the liquid in the middle chamber of. As a result, a combined force that is distributed and acts is formed on the surface of the addendum circular wall 26, and the combined force presses the addendum circular wall 26 inward in the radial direction. The addendum gap between the addendum 28 and the addendum circular wall 26 becomes narrower when the pressure difference between the discharge side and the suction side increases. This acts to prevent increased leakage flow due to the increased pressure differential. The addendum circular wall 26 is designed so that the necessary lubrication gap can exist between the addendum 28 and the addendum circular wall 26 even when the pressure between the suction side and the discharge side is maximized. ing.

In the axial direction, the pressure chamber 32 is closed by a casing cover 24, and a tooth tip circular wall 26 is in contact with the casing cover 24.

The gear pump 46 of the present invention illustrated in FIG.
Is constructed and operates in much the same manner as the gear pump 10 of the present invention illustrated in FIG. The description given in FIG. 1 will not be repeated in FIG. 2 when the two gear pumps 10, 46 are the same. Moreover, the same reference numerals are given to the same portions.

In the case of the gear pump 46 shown in FIG. 2, an elastic tip circular wall 36 is constructed differently from FIG. 1 with a pressure chamber 38 arranged on the outside thereof. The tooth tip circular wall 36 is located approximately 9 from the suction side, which is located at the lower side in FIG.
It extends outwardly around the gear wheels 14, 16 by an arc segment of 0 ° and is a unit with the pump casing 12 and transitions to the pump casing 12 at both ends. That is, the addendum circular wall 36 of the gear pump 46 is immovably positioned on the pump casing 12 on both sides. As a result, the addendum circular wall 36 is stably held and the gear 1
Even when the rotation directions of 4, 16 are mistakenly reversed, the operation can be performed without danger.

The suction-side end 40 of the addendum circular wall 36 merges into an elastic web 42 which extends outwards in a substantially radial direction, which web 42 is pumped on the other hand. It is formed integrally with the casing 12. This web 42
Allows the tip circle wall 36 to carry out a compensating movement when the tip circle wall 36 moves radially under pressure loading on its inner and outer sides, so that its suction side end. The part 40 is movable in the circumferential direction (this is suggested by exaggerated broken lines in FIG. 2).

The pressure chamber 38 is provided in the rear casing cover 2.
A passage 44 mounted in 4 and indicated by dashed lines
Is connected to the discharge side of the gear pump 46. Therefore, in the pressure chamber 38, exactly the same liquid pressure as that on the discharge side of the gear pump 46 is dominant. The tip circular wall of the invention, which is movable in the radial direction, can also be used in a gear pump with internal teeth. In that case, the addendum circular wall is arranged inwardly on the circular head surface of the internal gear or externally on the circular head surface of the external gear.

[Brief description of drawings]

FIG. 1 is a front view of the gear pump of the present invention opened.

FIG. 2 is a view similar to FIG. 1 of the second embodiment of the present invention.

[Explanation of symbols]

 10 Gear Pump 12 Pump Casing 14, 16 Gear 18 Drive Shaft 20 Feather Key 22 Floating Shaft 24 Casing Cover 26 Tooth Tip Circular Wall 28 Tooth Tip 30 Discharge Side End 32 Pressure Chamber 34 Opening 36 Tooth Tip Circular Wall 38 Pressure Chamber 40 Suction Side end 42 Web 44 Passage 46 Gear pump f, p Arrow

Claims (7)

[Claims] 1. A gear pump comprising a pump casing having one suction connection and one discharge connection, the pump casing enclosing two gears meshing with each other and rotatably mounted on the pump casing. One gear is non-rotatably arranged on the drive shaft supported and protruding from the pump casing, and the other gear is
In the type arranged rotatably on an idle shaft supported by a pump casing, the pump casing (12) has a tooth tip circular wall (26, 36) movable in the radial direction against spring force. , Gear (14, 1
6) has a liquid transfer region of each gear (14, 16) outside the tip circular surface, and the pump casing (12) has a pressure chamber (32) outside the tip circular wall (26, 36). , 38)
The pressure chamber (32, 38) communicates with the discharge side of the gear pump (10, 46) or the gear (14, 1) in the liquid transfer region of the gear (14, 16).
The liquid transfer region communicating with one point in the tooth rotation trajectory of 6) is the discharge side of the gear pump (10, 46) and the discharge side end (30) of the tip circular wall (26, 36). A gear pump, characterized in that it is located between and. 2. A discharge side end portion (30) of a tooth tip circular wall (26).
Is free to move in the radial direction,
The gear pump according to claim 1. 3. Both ends (30, 4) of the tip circular wall (36).
Gear pump according to claim 1, characterized in that 0) is fixedly located in the pump casing (12). 4. A tooth tip circular wall (26, 36) is formed in one piece in the pump casing (12) and is elastically deformable in the radial direction. The gear pump according to claim 1. 5. Gear pump according to claim 1, characterized in that the tooth top wall is inserted in the pump casing. 6. The tooth tip circular wall (36) has a respective gear (14,
16) is fixed to the pump casing (12) by a web (42) movable in the circumferential direction of 16),
The gear pump according to any one of claims 1 to 5. 7. At a defined pressure, which drives the drive shaft (18) rotatably and which allows the pressure chambers (32, 38) to be held constant or raised during a familiar running period. 7. A method for running-in a gear pump according to claim 1, characterized in that it is loaded.