JPH0148394B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear pump, in which a highly viscous liquid is sealed between a slippery sheet disposed on an end face of a gear and a lid.

A gear pump rotates a driving gear and a driven gear to transport fluid under high pressure, and requires a high degree of watertightness. Each of the gears mentioned above is arranged inside the main body case, and a lid body is attached to one end surface of the main body case.This kind of lid body is generally made of plastic material such as a synthetic resin with a high shrinkage rate such as polyacetal resin. Because it is made by molding, sink marks occur,
Its outer surface is difficult to be perfectly flat and is prone to minute irregularities, which creates a minute gap between the contact surface of the gear and the lid, allowing liquid to leak from the gap and causing the liquid pressure to drop. There were drawbacks such as a reduction in the transporting power of the gear pump, a reduction in precision due to abrasion of the convex portion on the outer surface of the lid body by the end face of the gear, and the occurrence of play. In order to solve this problem, between the gear installed in the main body case and the lid body,
By interposing a lubricious sheet with low sliding friction with the gear end surface, it compensates for the unevenness of the outer surface of the lid body, ensures watertightness of the contact surface between the gear and the lid body, and prevents liquid from flowing from the contact surface. We considered ways to prevent leaks.

However, even if the slippery sheet is interposed in this way, the irregularities on the outer surface of the lid cannot be sufficiently compensated for, and there is still a drawback that liquid leaks from the contact surface between the lid and the slippery sheet.

Therefore, the present invention has been made in consideration of the above points, in which a highly viscous liquid is sealed between the slippery sheet interposed between the gear and the lid, and the lid. By doing so, the gap between the contact surface of the slippery sheet and the lid body is eliminated, watertightness is improved, and a drop in hydraulic pressure due to liquid leakage is prevented.

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view of a gear pump A according to the present invention, in which 1 is a main body case having a suction passage 2 and a discharge passage 3, 4 and 5 are a pair of gears made of synthetic resin that mesh with each other; It is housed in a substantially figure-eight-shaped gear chamber 6 of 1. Of these, the drive gear 4 is insert-molded with a metal shaft 7, and in this case, as shown in FIG. Moreover, a dish-shaped recess 4b is provided in the side wall 4a to prevent the upper surface of the shaft 7 from protruding.

The other side of the shaft 7 passes through a hole 27 in the bottom wall 8 of the gear chamber 6, projects outward from the case side wall 1a, and forms a mortar-shaped inclined surface 27a at the outer peripheral edge of the hole 27. . Further, this hole 27 is surrounded by a concave wall 1b formed in the case side wall 1a, and a stepped portion 1b'' is formed on the inner wall 1b'.
Reference numeral 1 designates an elastic waterproof packing made of neoprene rubber or the like that is installed inside this stepped portion 1b''.This waterproof packing 11 is also attached to the inner wall 1 of the concave wall 1b.
The oil-impregnated bearing metal 12 for shaft support, which is press-fitted into b', is constantly pressed down with an appropriate pressing force, so that the conical part 11a bites into the mortar-shaped inclined surface 27a of the hole 27 for the shaft 7. is installed on.

On the other hand, the driven gear 5 has a recess 5 similar to the drive gear 4.
b is left on the ceiling wall 5a and the center is made hollow,
A fixed shaft 1 protrudes from the bottom wall 8 of the gear chamber 6 in this
3 is inserted and supported. The fixed shaft 13 is approximately half the length of the hollow portion, and the space between the fixed shaft 13 and the bottom wall 8 of the gear chamber 6 is constantly filled with liquid sucked by the gear pump A. When the friction surfaces of the gears become dry, this liquid is supplied to make the rotation of the gears 4 and 5 smooth.

It should be noted that both of the gears 4 and 5 have tooth surfaces roughened to relatively increase the speed of the air flow for discharging the air remaining in the gear chamber 6 at the start of suction.

The opening 9 of the gear chamber 6 is surrounded by a cylindrical annular wall 10, and a triangular threaded portion 10 is provided on the outer periphery of the annular wall 10.
It forms a. Reference numeral 14 denotes a disc-shaped lid body having an exhaust boat 15 communicating with the exhaust passage 3, which is fitted inside the annular wall 10 and is connected to the side wall 4a of the gears 4 and 5 and the ceiling wall 5a. A slippery sheet 16, such as a water-absorbing nylon sheet, interposed between the two gears maintains good lubricity with respect to the gears 4 and 5 by retaining moisture and having lubricity even when dry.

In this case, the slippery sheet 16 and the lid body 14 face each other, but if the lid body 14 is molded from a synthetic resin with a high shrinkage rate such as polyacetal resin, sink marks may occur and the gear Contact with 4 and 5 becomes worse. In particular, when the exhaust port 15 of sufficient length is provided upright in a part of the lid 14, the lid 14 tends to have minute irregularities due to local contraction or the like.

The problem of the present invention lies in this point. That is, the lid body 1
4 requires highly accurate flatness to ensure contact with gears 4 and 5, but it is difficult to prevent protrusions such as the exhaust port 15 or recessed objects such as the exhaust passage hole. It is necessary to form irregularities that impede flatness, and these two requirements are contradictory.

Therefore, the present invention provides the lid body 14 and the slippery sheet 16.
A high viscosity liquid 28 such as grease is applied between the two. Therefore, the slippery sheet 16 adheres tightly due to the adhesive force of the high viscosity liquid 28, thereby compensating for the unevenness of the lid body 14.

In the figure, reference numeral 17 denotes an O-ring for waterproofing between the lid 14 and the annular wall 10, which is fitted into a stepped portion 14a formed at the circumferential end of the lid 14. 1
Reference numeral 8 denotes a U-shaped tightening ring formed with a triangular threaded portion 18a that is screwed into the triangular threaded portion 10a of the annular wall 10. By screwing this, the rear side surface 14b of the lid body 14 is fixed to the opening end surface 19. It is tightened and fixed in the pressed position. Reference numeral 20 denotes a groove into which a tightening jig is engaged when screwing the lid 14 on.

Further, 21 is a projection for positioning a spacer member 21 for gap adjustment inserted between each end surface 4a, 5a of the gears 4, 5 and the slippery sheet 16; 24 is a support rod of the annular wall 10; and the annular wall 10 are connected to each other. 26 is a rubber hose disposed between the tank and the suction passage 2 (not shown).

According to the gear pump having the above configuration, when assembling this gear pump, the slippery sheet 16 is thin and easily damaged, and positioning to the main body case 1 is troublesome; By interposing a high viscosity liquid 28 between the lid 16 and the lid 16, the lid 14 can be temporarily attached to a predetermined position, and the lid 14 can be handled and incorporated into the main body case 1, increasing productivity. be able to.

In the thus assembled gear pump, when both gears 4 and 5 are rotated by a motor (not shown), liquid is sucked into the main body case 1 from the suction passage 2.
It flows out to the discharge port 15. As the gears 4 and 5 rotate, the inside of the main body case 1 is under high pressure, but a highly viscous liquid 28 is present between the lid 14 and the slippery sheet 16.
Since the fluid is sealed by the lid 14 and the slippery sheet 16, the fluid does not leak out of the main case 1 through the gap between the lid 14 and the slippery sheet 16, and the high pressure inside the main case 1 is maintained and the fluid flows through the discharge port 15. transported under high pressure to
In addition, since the liquid 28 on the slippery sheet 16 is sealed by the unevenness of the lid 14, the liquid 28 tightly adheres between the slippery sheet 16 and the lid 14.
Even if the gear pump is operated for a long period of time, it will not easily peel off and flow away. Various liquids can be used as the liquid 28, as long as they have a high chemical resistance to the slippery sheet 16 and the fluid. For example, if the fluid to be transported is water, grease may be used.
However, if a liquid 28 with a low viscosity is used, there is a risk that the liquid 28 will easily flow away, so a liquid with a high viscosity should be used.

According to the present invention having the above configuration, the driving gear 4 and the driven gear 5 are disposed within the main body case 1, the lid body 14 is attached to the main body case 1, and
A slippery sheet 16 is interposed between the lid 14 and each of the gears 4 and 5, and a highly viscous liquid 28 is sealed between the lid 14 and the slippery sheet 16 to improve the lubricity. The sheet 16 can be brought into close contact with the lid 14 in advance, making it easier to incorporate the slippery sheet 16, which requires careful handling, and improving productivity. By ensuring the contact state of the gears 4 and 5 due to the unevenness, liquid leakage can be prevented and fluid can be transported under high pressure.

[Brief explanation of drawings]

FIG. 1 is an exploded perspective view of a gear pump embodying the present invention, and FIG. 2 is a horizontal sectional view taken along the line B--B in FIG. 1 of the same embodiment in an assembled state. DESCRIPTION OF SYMBOLS 1... Main body case, 4... Drive gear, 5... Driven gear, 14... Lid body, 16... Slippery sheet, 2
8...Liquid.

Claims (1)

[Claims] 1 A driving gear 4 and a driven gear 5 are disposed inside the main body case 1, a lid 14 is attached to the main body case 1, and a slippery sheet 16 is placed between the lid 14 and each of the gears 4 and 5. A gear pump characterized in that a highly viscous liquid 28 is sealed between the lid 14 and the slippery sheet 16.