JPS59165882A - Gear pump - Google Patents

Abstract

PURPOSE:To prevent grinding by fine grains in the liquid and corrosion by medicament by forming a driven shaft rotatably holding a driven gear with ceramic having high hardness and strong corrosion resistance. CONSTITUTION:The bearing hole 16 of a driven gear 6 is made slightly larger than the diameter of a driven shaft 13, thus a small gap (t) is assured between the bearing hole 16 and the outer periphery of the driven shaft 13, and the driven gear 6 is rotatably fitted to the driven shaft 13. Therefore, fine grains in the fluid infiltrated into the gas (t) during the operation are stuck to the inner periphery of the bearing hole 16, and the contact portion of the driven shaft 13 with the bearing hole 16 is ground by these fine grains, but since the driven shaft 13 is formed with ceramic having high hardness and strong corrosion resistance, it is not made slender due to grinding by fine grains in the liquid. In addition, even if medicament is mixed in the liquid, corrosion by medicament can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear pump in which a driven shaft of the gear pump is made of ceramic. .

Gear pumps have a wide pressure range and are used to transport fluid at a constant speed, so 1 l IN? # Widely used for transporting various plate corrugations of oil hemorrhoids. A gear pump is composed of a driving gear and a driven gear that mesh with each other inside the nudging, and pumps fluid by transmitting power to the driving gear and rotating both gears. While the gear is fixed to the drive shaft, the driven gear is often loosely attached to the driven shaft, and is rotated around the driven shaft by one drive of the drive gear. When the outflow passage of the wave passage in which the gear pump is disposed is closed while the gear pump is being driven, the fluid pressure on the discharge port 5b side in the casing 5a increases as shown in FIG. The driven gear 5d receives pressure toward the suction port 5e, and rotates at high speed while the inner peripheral surface of the bearing hole 5f of the driven gear 5d is strongly pressed against the outer peripheral surface of the driven shaft 5g. However, since the conventional driven shaft 5g was made of various copper materials, synthetic resins, etc., it entered the gap between the driven shaft 5g and the bearing hole 5f as shown in No. 51 (b).
The outer circumferential surface of the driven shaft 5g made of the above-mentioned material is ground by the fine particles 5h in the fluid that adhere to the inner circumferential surface of the driven shaft 5g, and over a long period of time the driven shaft 5g becomes thinner and the driven gear 5a becomes thinner. This has the disadvantage that it causes sticking and reduces the functionality of the gear pump. In other words, this type of gear pump has features such as small size and high pressure, so it is widely used as a pump for transporting chemical solutions in gardening sprayers, for example, but if the spraying of chemical solutions is briefly stopped while the gear pump is running, There was a tendency for the outer circumferential surfaces of the five driven shafts to be scraped due to fine particles such as silicon dioxide in the chemical solution adhering to the inner circumferential surface of the bearing hole 5f of the driven gear 5d. Also, many of these driven shafts (5g) are plated for insurance purposes in order to prevent rust and reduce the rotational friction coefficient of the gears to ensure smooth rotation, but is it plated? Steel materials have low corrosion resistance against this type of chemical solution, and when they are eaten away by the chemical solution and the diameter of the driven shaft 5g increases, the gap between the bearing hole 5f and the outer circumferential surface of the driven shaft 5g becomes smaller, causing rotational M friction between both 5f and 5g. However, the problem was that the gear pump's function deteriorated due to the large size of the gear pump. In particular, this type of gear pump has a precise structure,
Moreover, in recent years, high speed and high accuracy have been increasingly required, so even a slight deviation in the diameter of the driven shaft as described above becomes an unacceptable defect in gear pump performance.

Therefore, the present invention has been made for the purpose of providing a gear pump that eliminates the drawbacks of the conventional ones, and has a driven shaft on which a driven gear is loosely attached, which has high hardness and strong corrosion resistance, and has a low coefficient of thermal expansion. It is made of relatively small ceramic material.

The present invention will be described in detail below with reference to the drawings. 1fM is an exploded perspective view of the gear pump, ab4 is the same section, and l is a casing made of synthetic resin. A suction pipe 2 is provided vertically at the bottom, and a discharge pipe 3 is connected to the rear wall of the casing l.

Reference numerals ``la'' and ``la'' denote mounting plates that are connected to the lower portions of both sides of the casing 1, and are used to mount and fix the gear pump to a support stand (not shown). Reference numeral 4 denotes a pedestal on which a driving gear 5 and a driven gear '6 which are aligned with each other are mounted. By fitting the pedestal 4 into the opening side receiving part 7 of the casing l, both gears 5 and 6 are attached to the casing 1. Interior decoration. Reference numeral 8 denotes a drive shaft to which the drive gear 5 is fixed, and is made of a copper material such as stainless steel.The drive shaft 8 is rotatably inserted into a bearing hole 9 formed in the base 4, and its tip is freely supported in a bearing groove 10 recessed in the interior of the casing l. Both sides of the tip 8a of the drive shaft 8 are chamfered to have a substantially rectangular cross section, and a brass drive ring 11 is fixed to the tip (see No. 3-).

Further, an oil-impregnated bearing ring 12 is installed in the bearing groove lO, and the drive ring 11 at the tip of the drive shaft 8 is attached to the bearing ring 1.
2 and is rotatably loosely fitted into the interior of the holder. Reference numeral 13 denotes a driven shaft made of zirconia-based ceramic having an average crystal grain size of about i-lo, and its both ends are connected to a bearing groove j4 recessed in the inner wall of the pedestal 4 and a recessed part in the interior of the casing l. It is freely rotatably supported in the bearing groove 15. The bearing hole 16 of the driven gear 6 is slightly larger than the diameter of the driven shaft 13, and a space at is secured between the bearing hole 16 and the outer peripheral surface of the driven shaft 13, so that the driven gear 6 is rotated by the driven shaft 13. The inner diameter of the freely attached bearing groove 15 is slightly larger than the diameter of the driven shaft 13, and a large number of bearing projections 17 are formed on its inner peripheral surface.
A large number of protrusions are provided at equal intervals (see FIG. 4), and the tip of the driven shaft 13 is rotatably held by each protrusion 17. Each protrusion 17 has some flexibility and bends as appropriate to absorb diametric variations in the driven shaft 13.
The axis O of No. 3 can hold the center of rotation.

Reference numeral 18 denotes a thin film spacer, which is interposed between the inner surface of the casing l and the end surface of each gear 5.6, and adjusts the gap between the two to tightly fit each gear 6.6 into the casing l. It is something that fits.

This gear pump is constructed as described above, and the drive shaft 8
When driven by a motor (not shown) and rotating both gears 5 and 6, fluid is sucked in from the suction pipe 2 and discharged from the discharge pipe 3. When the fluid outflow path is closed while driving both gears 5.6, the fluid pressure on the discharge pipe 3 side inside the casing l increases as described above, and this pressure causes both gears 5.6 to close.
is pushed toward the suction pipe 2 side. Therefore, the driven gear 6 loosely attached to the driven shaft 13 is pushed toward the discharge pipe 2 side, and the inner peripheral surface of the bearing hole 16 is strongly pressed against the outer peripheral surface of the driven shaft 13, and continues to rotate at high speed. The particulates in the fluid that have entered the interior adhere to the inner surface of the bearing hole 16, and these particulates polish the part of the driven shaft 13 that comes into contact with the bearing hole 16, but the driven shaft 13 does not have flat hardness. Since it is made of ceramic that has the same properties, it will not become thinner due to such polishing. In particular, if the driven gear 6 is made of metal such as brass or stainless steel, the surface temperature of the driven gear 13 will increase due to the heat generated by sliding when rotating at high speed while the discharge pressure is applied. However, when the driven shaft 13 is stopped after use, it is rapidly cooled down, and due to such repeated heating and cooling, the driven shaft 13 is annealed, but if it is made of ceramic, this can be prevented. In addition, the coefficient of thermal expansion is small (for example, S combination B of zirconia ceramics, '7xlo'/'O), *Moving gear 6
Sufficient clearance can be secured between the two. Furthermore, even if chemicals are mixed into the fluid, ceramics have strong corrosion resistance and will not be corroded by the chemicals. As such ceramic, zirconia group (Er
as ) In addition to ceramics, alumina-based (mul*Om>
, beryllia-based (B.0), saponified ceramics such as magnesia A (Mgo), boron carbide-based (BO),
Beryllium carbide (memo), tungsten carbide M (
Carbide ceramics such as No. 10) and other mouse ceramics can also be used.

As explained above, in the gear pump according to the present invention, the driven kJ shaft 13 on which the driven gear 6 is loosely attached is made of ceramic having local hardness and strong corrosion resistance, so that it may not be abraded by fine particles in the fluid. It will not be corroded by chemicals.

[Brief explanation of drawings]

The figures show an implementation hook of the present invention, in which Fig. 1 is an exploded perspective view of the gear pump, Fig. 2 is a sectional view thereof, Fig. 3 is a partial perspective view, Fig. 4 is a partial sectional view, and Fig. 5 is a partial perspective view of the gear pump. The figure is the conventional one.
It is a Ut side view. l... Casing 5... Drive gear 6... Driven gear 8... Drive shaft 13... Driven shaft tB Applicant Kyushu Hitachi Maxell Co., Ltd. Patent attorney Yuki Taka Matsutoshi Figure 3 11 5th (a) 41stffi1

Claims (1)

[Claims] A drive gear 5 fixed to a drive shaft 8 in the casing l;
1. A gear pump in which a driven gear 6 loosely attached to a driven shaft 13 is housed therein, characterized in that the driven shaft 13 is made of ceramic.