JPH0435591Y2 - - Google Patents

Description

[Detailed explanation of the idea] [Industrial application field] The present invention relates to improvements in internal gear pumps.

[Prior Art] To explain the internal gear pump with reference to FIGS. 2 and 3, a casing 1 has a casing cover 2.
is attached to the casing 1, and the main shaft 3 passes through the casing 1. An external gear 4 is attached to the main shaft 3, and an internal gear 5 internally meshed with the external gear 4 is slidably housed in the casing 1.

A crescent 6 is interposed in the space defined by both gears 4 and 5, and this crescent 6 and the side surfaces 1a and 2a of the casing and casing cover move the fluid from the high pressure area on the discharge side to the low pressure area on the suction side. It is designed to seal leaks.

In addition, on the inner circumferential surface 1b of the casing 1 which is in sliding contact with the outer circumferential surface of the internal gear 5, balance chambers 7 and 8 (balance chamber 8 is shown in FIG. ) is formed to reduce the radial thrust acting on the internal gear 5.

With this structure, when the external gear 4 is rotated counterclockwise, the internal gear 5 is driven and rotated in the same direction, and both gears 4 and 5 direct the fluid to the suction port (not shown) on the right side of FIG. It is designed to be sucked in from the air and discharged at high pressure from a discharge port (not shown) on the left side of FIG.

"Problems with the Prior Art" In conventional internal gear pumps, the casing 1 was made of gray cast iron, and the internal gear 5 and external gear 4 were made of charcoal steel. The sliding torque due to friction between the inner circumferential surfaces 1b of No. 1 was large, and both the outer circumferential surface and the inner circumferential surface were worn. Therefore, when replacing consumable parts, it was necessary to replace the internal gear 5 and the casing 1 at the same time. Since the casing 1 is a base member, maintenance costs are high. In addition, due to the backlash between the internal and external teeth, there is a problem in that the play in the internal gear causes the teeth to repel each other and generate noise.

In general, various countermeasures against wear of crescent-type gear pumps are known. For example, Japanese Patent Laid-Open No. 60-85284 discloses a technology for reducing wear and preventing scratches by using low carbon steel for gears. ing. However, in such known technology, during long-term operation, the meshing parts of both the internal gear and the external gear wear out, and the meshing breakdown increases, so both gears must be replaced. , replacement work is troublesome.

In addition, Japanese Utility Model Application No. 61-86585 discloses that the rotor and stator of an internal gear pump are made of different materials,
A technique has been disclosed in which the sliding surfaces of the stator and rotor are polished by "familiar rotation" and the sliding surface polishing process is not necessary. However, even with such known techniques, similar problems occur when the rotor and stator wear out.

[Problems to be Solved] Therefore, an object of the present invention is to provide an internal gear pump that can reduce maintenance costs and easily achieve low noise.

[Means for Solving the Problem] According to the present invention, an external gear is attached to the main shaft passing through the casing, and an internal gear internally meshed with the external gear is slidably housed in the casing. A crescent interposed in the space defined between the external gear and the internal gear prevents leakage from the high pressure area on the discharge side to the low pressure area on the suction side that occurs when transferring fluid. A balance chamber is provided on the side of the casing that is in sliding contact with the outer circumferential surface of the internal gear and communicates with a high pressure area on the discharge side and a low pressure area on the suction side. In an internal gear pump that reduces radial thrust acting on the gear, a surface hardening layer is formed on the inner circumferential surface of the casing that is in sliding contact with the outer circumferential surface of the internal gear, and the internal gear is It is made of a material such as a copper alloy that has lower hardness than the surface hardening layer and the external gear and has sliding properties.

[Description of effects] Since the present invention is configured as described above, during operation, the internal gear rotates on the sliding surface of the casing, but at this time, the internal gear, which has a relatively low hardness, rotates on the sliding surface of the casing. However, the casing does not wear out. The same applies to external gears. If the internal gear wears out and generates noise during long-term use, it is sufficient to remove the casing cover and replace only the internal gear. In particular, when the casing wears out, substantially the entire device must be replaced, but according to the present invention, only the internal gear needs to be replaced, so maintenance costs can be reduced.
In addition, by using a material with excellent sliding properties for the internal gear, the sliding torque on the sliding surface with the casing and the meshing surface with the external gear can be reduced, resulting in a longer lifespan of the casing and external gear. You can improve. Furthermore, since copper alloy and the like have a small coefficient of repulsion, the repulsion between the external gear and the internal gear is alleviated, and the noise generated by meshing can be reduced.

[Examples] Examples of the present invention will be described below with reference to the drawings. In FIG. 1, parts corresponding to those in FIGS. 2 and 3 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 1, a casing 10 is made of gray cast iron, and a surface effect treatment layer 11 according to a known technique is formed on the inner circumferential surface of the casing 10 that comes into sliding contact with the internal gear 5. As shown in FIG. The internal gear 5 is made of a material such as a copper alloy, which has lower hardness than the surface hardened layer 11 and the external gear 4, has excellent sliding properties, and reduces the coefficient of repulsion with external teeth.

Therefore, the internal gear 12 and the casing 10
The sliding characteristics are good, improving the mechanical efficiency and durability of the pump. In addition, maintenance costs can be reduced because only the internal gear needs to be replaced due to wear. Furthermore, the noise generated between the external and internal teeth is smaller than before.

[Effects of the invention] As described above, according to the present invention, the following excellent effects are achieved.

() Only the internal gear wears out, so the life of the casing and external gear is long.

() By removing the casing cover, the internal gear can be easily replaced, reducing maintenance costs.

() Replacing the internal gear will extend the life of the pump itself.

() Good sliding properties and improved mechanical efficiency.

() Less noise is generated due to meshing between the internal and external gears.

[Brief explanation of drawings]

FIG. 1 is a front view of essential parts showing an embodiment of the present invention, and FIGS. 2 and 3 are a front view and a side sectional view showing the right half of a conventional internal gear pump. . 3... Main shaft, 4... External gear, 5... Internal gear, 6... Crescent, 7, 8... Balance chamber,
10...Casing, 11...Surface hardening treatment layer.

Claims (1)

[Scope of utility model registration request] An external gear is attached to the main shaft passing through the casing, and an internal gear internally meshed with the external gear is slidably housed in the casing and covered with a casing cover. A crescent interposed in the space defined by the external gear and internal gear and side plates provided on both sides of the external gear and internal gear prevent the leakage that occurs from the high pressure area on the discharge side to the low pressure area on the suction side. An internal gear pump that is sealed and provided with a balance chamber communicating with a discharge side high pressure area and a suction side low pressure area on the casing side that is in sliding contact with the outer peripheral surface of the internal gear to reduce the radial thrust acting on the internal gear. A surface hardening layer is formed on the inner circumferential surface of the casing that is in sliding contact with the outer circumferential surface of the internal gear, and the internal gear has a hardness lower than that of the surface hardening layer of the casing and the external gear, and An internal gear pump characterized by being made of a sliding material such as a copper alloy.