JPH10196553A - Gear pump or hydraulic motor, and manufacture of pump body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the change of the volume efficiency in a structure where the top balance is held by bringing a tip of a gear slidably into contact with an inner peripheral face of a pump body, by making the pump body for accommodating a pair of gears, out of cast iron, and casting a cushioning member mainly composed of copper, on an inner peripheral face of the pump body. SOLUTION: A pump body 6 of a gear pump 1 is made of cast iron, and a suction port B side of a body inner peripheral face 7 formed in the pump body 6, is made of a cushioning material A mainly composed of a cupper material. The cushining material A is softer than the material of the gears 4, 5, and has rigidity as much as possible, and high melting point, and the copper material is preferably used. By coating the corresponding part of the body inner peripheral face 7 with the cushionining material A mainly composed of copper, the deposition of the scrap chipped by the tips of the gears 4, 5, to the tips of the gears 4, 5 can be prevented, when the optimum clearance is formed as the top balance formed in the initial running-in, and the desirable conformability can be kept.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic gear pump or a hydraulic motor (hereinafter simply referred to as a gear pump). The present invention relates to a hydraulic gear pump or a hydraulic motor for maintaining a top balance by sliding an inner peripheral surface of a pump body (so-called gear pocket) with a gear tip, and a method of manufacturing a pump body.

[0002]

2. Description of the Related Art An example of a conventional gear pump is shown in FIGS. The gear pump 50 houses a pair of meshing gears 53 and 54 provided on a drive shaft 51 and an idler shaft 52 so as to be in sliding contact with a gear pocket inner peripheral surface 56 of a pump body 55. Are provided on the front cover 57 and the rear cover 58.
The body 55, the front cover 57, and the rear cover 58 are fixed to each other by fixing means such as bolts which are rotatably supported at zero, and are appropriately sealed with an oil seal or the like. In the drawings, reference numerals 61 and 62 denote side bushes or side plates for maintaining a so-called side balance of the gear.

In the above configuration, when the drive shaft 51 is rotated in the direction of the arrow, the pressure inside the discharge port 63 rises to the relief pressure set value of the equipment connected to the discharge port 63, and the gears 53, 54 55 is pressed against the suction port side 64 of the inner peripheral surface 56 and the portion of the inner peripheral surface is the gear 53,
It is scraped off by 54. Thereby, the gear pump 5
The so-called top balance of 0 is maintained, and a pump with stable volumetric efficiency can be provided. In addition, the discharge port side 6
When the pressure fluid flows into one of the suction port 3 and the suction port 64 and the other is used as a discharge port, the hydraulic fluid operates as a hydraulic motor having the drive shaft 51 as an output shaft. Is scraped off by the gears 53 and 54.

[0004]

However, the material of the pump body 55 is made of aluminum from the viewpoint of weight reduction and easy processing, and is softer than the materials of the gears 53 and 54. Therefore, the debris shaved off by the gear tooth tip may not be powdery but rather large. In such a case, serious problems such as contamination of the hydraulic oil as well as clogging inside the hydraulic equipment connected to the pump 50 are caused. May occur. In order to solve this problem, a method in which the pump body 55 is made of cast iron is conceivable. In this case, as compared with the case of aluminum, the shavings are powdery, but the gear 5
Similarly to the material of the pump body 55, the materials of 3, 54 are iron-based materials (for example, chromium molybdenum steel or the like). The inner peripheral surface of the pump body 55 is further scraped off by the tooth tip, and a vicious cycle is repeated in which the scraped-off debris is again welded to the tooth tip.

In view of the foregoing, the present invention maintains good initial clearance (initial run-in) without the debris shaved off by the gear teeth on the inner peripheral surface of the pump or motor body being welded to the gear teeth. Another object of the present invention is to provide a method of manufacturing a high-performance hydraulic gear pump or motor and a pump body with little fluctuation in volumetric efficiency.

[0006]

According to a first aspect of the present invention, there is provided a hydraulic gear pump or a hydraulic motor in which a tooth tip of a gear is brought into sliding contact with an inner peripheral surface of a pump body to maintain a top balance. The pump body that houses the gears is made of cast iron, and a buffer material mainly composed of copper is cast into the inner peripheral surface of the pump body.

According to the present invention having the above structure, in a hydraulic gear pump or motor, the inner peripheral surface of the pump body is formed of a buffer material mainly composed of copper having a lower hardness than the gear material, so that the inner surface of the pump body is shaved off by the gear teeth. The debris does not adhere to the tooth tips, maintains an appropriate top balance during the initial running-in operation, and maintains the initial performance.

The second invention is characterized in that the buffer material mainly made of copper is cast at a suitable position on the low pressure side in the inner peripheral surface of the pump body which accommodates the paired gears.

According to the present invention having the above-described structure, the amount of copper used is reduced by setting the range in which the cushioning material mainly composed of copper is cast in the sliding contact area between the gear tooth tip and the inner peripheral surface of the pump body. Can be reduced.

In a third aspect of the present invention, when manufacturing a casting for a pump body containing a pair of gears, a buffer material mainly composed of copper powder is sprayed onto a core forming an inner peripheral surface of the pump body to obtain a required thickness. The buffer material is melt-fixed to the inner peripheral surface of the formed pump body by forming the above layer and casting the pump body material.

According to the present invention having the above-described structure, a cushioning material mainly composed of copper powder is sprayed on a core to form a layer having a required thickness. Welds firmly.

[0012]

FIG. 1 shows an embodiment of a gear pump according to the present invention. This gear pump 1 comprises a drive shaft 2, an idler shaft 3, a drive gear 4 provided on each shaft, a driven gear 5, and a drive gear 4 and a driven gear 5. A pump body 6 that houses the gears 4 and 5 is provided. In addition, a front cover and a rear cover (both not shown) similar to those of the conventional example are provided. The other structure is the same as the conventional example, and the description is omitted. In the drawing, reference numeral 7 denotes an inner peripheral surface of the pump body, 8 denotes a suction port, 9 denotes an oil reservoir connected thereto, 10 denotes a discharge port, and 11 denotes an oil reservoir connected thereto.

The pump body 6 is made of cast iron (for example, C
2.7 to 3.0%, Si 1.0 to 1.6%, Mn
0.4 to 1.0%, P0.3 to 1.0%, S0.6
FC material, FCD material, FCV
It is composed of materials. ), And is formed of a buffer material A mainly composed of a copper material having an appropriate width and an appropriate thickness on the suction port 8 side of the body inner peripheral surface 7 formed inside the pump body 6. The cushioning material is softer than the material of the gear, has as much rigidity as possible, and has a high melting point, and a copper material is most preferable from experimental results. Further, it is preferable that the width to be adhered is in a range of about 45 degrees centered on the suction port indicated by α in the figure from the experimental results.

It is easy to cast the buffer material A at the time of manufacturing the material of the pump body 6, and the manufacturing procedure will be described. In FIG. 2, B denotes a material production core of the pump body 6, and the buffer material powder A is sprayed to a required thickness on a portion corresponding to the above-described position on the inner peripheral surface forming portion b of the core B. At this time, it is preferable that the buffer material to be sprayed is previously blended with copper powder and iron powder similar to the material of the pump body. Alternatively, it may be formed and sintered in this shape in advance and attached to the core.

The cushioning material A is mounted in an outer frame (not shown) using the sprayed core, and the iron material of the pump body is supplied and cast by a conventional method. At this time, the buffer material melts into the pump body material and the iron material and the buffer material are firmly connected.

In the above configuration, when the drive shaft 2 is rotated in the direction of the arrow as in the conventional example, the pressure in the oil sump 11 on the discharge port side rises to the relief pressure set value of the device connected to the discharge port 10, and the gear 4 and 5 are inner peripheral surfaces 7 of the pump body 6
Is pressed against the suction port 8 side.

However, the corresponding portions of the inner peripheral surface 7 are gears 4, 5
Although it is covered with a cushioning material mainly composed of copper, which has a lower hardness than that of the material, it creates the optimal clearance as the top balance formed during the initial leveling operation, but the debris shaved off by the gear tooth tip There is no welding first, and thereafter the inner peripheral surface 8 of the pump body is not scraped more than necessary.

[0018]

As described above, according to the present invention, the cushioning material mainly composed of copper is cast into the inner peripheral surface of the pump body, so that the debris shaved off by the gear teeth during the initial leveling operation can be removed. There is no welding first, the top clearance between the gear tooth tip and the inner peripheral surface of the pump body is maintained, and a good conforming state is maintained. Further, according to the second aspect of the present invention, the range in which the cushioning material mainly composed of copper is cast is set at an appropriate position on the low pressure side in a sliding contact range between the gear tooth tip and the inner peripheral surface of the pump body, thereby reducing the amount of the cushioning material used. Can be reduced. According to the third aspect of the present invention, a powder obtained by blending copper powder and iron powder is sprayed onto the core as a cushioning material, so that the cushioning material is firmly connected to the cast iron, which is a material of the pump body, and a buffer for a necessary portion is buffered. The casting of the material is easy,
In addition, there is an effect that the used amount can be reduced.

[Brief description of the drawings]

FIG. 1 shows a longitudinal sectional view of a gear pump or a hydraulic motor according to the present invention.

FIG. 2 is a perspective view of a core used when producing a pump body.

FIG. 3 shows a longitudinal sectional view of a conventional gear pump or hydraulic motor.

FIG. 4 is a sectional view taken along line XX in FIG. 3;

[Explanation of symbols]

 Reference Signs List 1 gear pump or hydraulic motor 4 drive gear 5 driven gear 6 pump body 7 body inner peripheral surface 8 suction port A cushioning material B core

Claims (3)

[Claims] In a hydraulic gear pump or a hydraulic motor in which a tooth tip of a gear is slidably brought into contact with an inner peripheral surface of a pump body, a pump body housing a pair of gears is made of cast iron. A gear pump or a hydraulic motor, wherein a cushioning material mainly composed of copper is cast on a peripheral surface. 2. The range in which the buffer material mainly made of copper is cast is as follows.
2. The gear pump or the hydraulic motor according to claim 1, wherein the low-pressure side is located at an appropriate position in the inner peripheral surface of the pump body that houses the paired gears. 3. When manufacturing a pump body casting that houses a pair of gears, a buffer material mainly composed of copper powder is sprayed on a core forming an inner peripheral surface of the pump body to form a layer having a required thickness. A method for manufacturing a pump body of a gear pump or a hydraulic motor, wherein the buffer material is melted and fixed to an inner peripheral surface of the formed pump body by casting a pump body material.