JPH06179227A - Gear pump - Google Patents

Abstract

PURPOSE:To contrive to reduce the noise at the running of a gear pump, to prolong its working and improve its pumping efficiency. CONSTITUTION:The gear pump concerned consists of a driving gear 1, a driven gear 2, a case 3, in which the two gears are internally installed, and a base 4 for enclosing the case 3. Its respective component parts are made by injection- molding material, which is prepared by mixing carbon fiber, tetrafluoroethylene resin and zinc oxide whisker with PPS resin. Due to the anisotropism relaxing effect of mold shrinkage factor by the zinc oxide whisker, the prevention of the wear due to malformation and the lowering of the noise due to vibration damping effect become possible. Further, due to the reducing effect of dynamic friction by the tetrafluoroethylene resin, the wear of the gears can by prevented from occurring. Accordingly, a low noise and long life gear pump can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gear pump for transferring liquid.

[0002]

2. Description of the Related Art Conventionally, a gear pump of this type has been shown in FIGS. 1 and 2, for example. 1 is a cross-sectional configuration diagram, and FIG. 2 is a cross-sectional view of the liquid passage portion taken along the line AA in FIG.

The drive gear 1 and the driven gear 2 have the same module, the same number of teeth, and the same width, and are installed in a case 3 having a substantially cup shape and having an inlet 3a and an outlet 3b. The drive gear 1 and the driven gear 2 are configured to rotate with a slight gap provided between the drive gear 1 and the driven gear 2 in the radial direction and the axial direction of the gear. The opening side of the case 3 is closed by a base 4 via an O-ring 5.

The drive gear 1 and the driven gear 2 are supported on the case 3 and the base 4 by a drive shaft 6 and a driven shaft 7, respectively.
Rotate with each tooth engaged. The drive gear 1 and the drive shaft 6 are press-fitted and fixed. Drive shaft 6 is oil seal 8
It is watertightly supported by. Further, the case 3 and the base 4 are integrally fixed to the support base 10 with screws 9. An electric motor 11 for driving a pump is fixed to the support base 10 with a screw 12, and the drive shaft 6 and an output shaft 13 of the electric motor 11 are connected via a spring joint 14. The drive gear 1 and the driven gear 2 are formed by injection molding a resin material in which 20% by weight of carbon fiber is mixed with 80% by weight of polyphenylene sulfide resin (hereinafter referred to as PPS resin), and the case 3 and the base 4 are made of polyacetal resin. It was formed by injection molding.

The operation of this conventional gear pump is as follows. When the electric motor 11 is supplied with power, it rotates in the direction of arrow B in FIG. Rotational power is transmitted to the drive shaft 6 via the spring joint 14, and the drive gear 1 and the driven gear 2 are respectively shown in FIG.
It rotates in the directions of arrows C and D in the inside. As a result, the liquid in the gap formed by the teeth of the drive gear 1 and the driven gear 2 and the case 3 and the base 4 flows from the suction port 3a to the discharge port 3b.
Sent to the side. At this time, the drive gear 1 and the driven gear 2 mesh with each other in the central portion to block the movement of the liquid from the suction port 3a to the discharge port 3b, so that the liquid does not return to the supply port 3a side again. As described above, the liquid can be transported by rotating the two gears.

[0006]

However, the gear pump of the above-mentioned conventional structure has problems that vibration noise during operation is large, operating life time is relatively short, and pump efficiency is relatively low. That is, in this type of gear pump, since the liquid is confined in the voids formed by the teeth of the drive gear 1 and the driven gear 2, the case 3 and the base 4, the liquid is conveyed, so that the outer diameter portion and both end portions of the gear are The sliding gap should be set as small as possible. For example, transport output 10W
For gear pumps of about the same size, the sliding clearance is usually 5/10.
Unless set to 0 mm or less, good pump efficiency cannot be obtained.

However, the driving gear 1 and the driven gear 2 are made of PP.
Since the resin material in which the carbon fiber is mixed with the S resin was injection-molded, anisotropy was generated in the molding shrinkage due to the orientation of the carbon fiber during the injection flow, and the required dimensional accuracy could not be obtained. In addition, the case 3 and the base 4 were injection-molded with polyacetal resin, but the material itself had a large molding shrinkage ratio, and the flatness of the gear sliding surface after molding and the deformation of the entire structure could not be avoided.

For this reason, when the drive gear 1, the driven gear 2, the case 3 and the base 4 are assembled, the fitting gap size is locally too large or they are in contact with each other. Since operation is performed in this state, vibration noise is generated due to rubbing of the contact portion, operating life is shortened due to accelerated wear of parts, and pump efficiency is reduced due to excessive gap size. In addition, when the gear pump is used for transporting tap water, scale components in the water may be accumulated with the lapse of use time, and the rotations of the drive gear 1 and the driven gear 2 may be locked and unusable. .

It is an object of the present invention to solve the above problems and provide a gear pump having low vibration, long life and high pump efficiency.

[0010]

The present invention comprises a pair of gears for achieving the above object, a case for accommodating the gear and a base for closing the case. The gear, the case and the base are made of PPS resin. In addition, a gear pump is formed by injection molding a resin material containing carbon fiber, tetrafluoroethylene resin, and zinc oxide whiskers.

[0011]

According to the present invention, since the compounded zinc oxide whiskers have a tetrapod-like three-dimensional structure, the carbon fiber is prevented from being oriented in the injection flow direction during injection molding, so that the molding shrinkage is anisotropic. There is no sex. Therefore, the required dimensional accuracy can be obtained, the flatness is insufficient, and the deformation of the entire structure is made smaller than before. Therefore, when the drive gear, the driven gear, the case, and the base are assembled, the fitting gap size can be appropriately set, vibration noise due to rubbing of the contact portion can be prevented, and wear of parts can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. Since the structure is the same as that of the conventional gear pump, it will be described with reference to the same drawings. FIG. 1 is a sectional configuration diagram, FIG.
FIG. 2 is a sectional view of a liquid passage portion taken along the line AA in FIG.

The drive gear 1 and the driven gear 2 have the same module, the number of teeth and the tooth width, and are installed in a case 3 having a suction cup 3a and a discharge port 3b which are substantially cup-shaped. The drive gear 1 and the driven gear 2 are configured to slide with a slight gap between the drive gear 1 and the driven gear 2 and the case 3 in both the radial direction and the axial direction of the gear. The opening side of the case 3 is closed by a base 4 via an O-ring 5.

The drive gear 1 and the driven gear 2 are both supported by the case 3 and the base 4 by the drive shaft 6 and the driven shaft 7, respectively, and rotate with the teeth engaged with each other. The drive gear 1 and the drive shaft 6 are press-fitted and fixed. The drive shaft 6 is watertightly supported by an oil seal 8. Further, the case 3 and the base 4 are integrally fixed to the support base 10 with screws 9. Further, an electric motor 11 for driving a pump is fixed to the support base 10 with a screw 12, and the drive shaft 6 and the electric motor 11 are further fixed.
The output shaft 13 is connected via a spring joint 14.

The operation of this gear pump is as follows. When the electric motor 11 is supplied with power, it rotates in the direction of arrow B in FIG. Rotational power is applied to the drive shaft 6 via the spring joint 14.
Therefore, the drive gear 1 and the driven gear 2 rotate in the directions of arrows C and D in FIG. 2, respectively. As a result, the liquid in the space formed by the teeth of the drive gear 1 and the driven gear 2, the case 3, and the base 4 is sent from the suction port 3a to the discharge port 3b side. At this time, the driving gear 1 and the driven gear 2
Since they are engaged with each other at the central portion to block the movement of the liquid from the suction port 3a to the discharge port 3b, the liquid does not return to the suction port 3a side again. As described above, the liquid can be transported by rotating the two gears.

The drive gear 1, the driven gear 2, the case 3,
The base 4 is formed by injection molding a resin material in which 50% by weight of PPS resin is mixed with 20% by weight of carbon fiber, 15% by weight of tetrafluoroethylene resin and 15% by weight of zinc oxide whisker.

The zinc oxide whiskers compounded in the material have a tetrapod-like three-dimensional structure, and therefore, in order to prevent the carbon fibers from being oriented in the injection flow direction at the time of injection molding, the molding shrinkage ratio is almost anisotropic. Does not happen. In the compounding ratio of this embodiment, the shrinkage ratios are about 0.2% and 0.3% in the flow direction and the direction perpendicular to the flow, respectively. Therefore, the transferability to the mold shape is good, the flatness and the deformation of the entire structure can be made smaller than before, and the required dimensional accuracy can be obtained.

Therefore, when the drive gear 1, the driven gear 2, the case 3, and the base 4 are assembled, the fitting gap size can be set appropriately, so that vibration noise is generated due to the friction of the contact portion due to the variation in the component size, and the component noise. Wear can be prevented, noise can be reduced, life can be extended, and pump efficiency can be improved. Further, the zinc oxide whiskers have a vibration damping effect, and the vibration noise when the drive gears 2 engage and collide with each other is rapidly attenuated, and the operation noise can be reduced.

Further, since the surface dynamic friction coefficient can be lowered by the action of the tetrafluoroethylene resin, the wear of the tooth surface due to the meshing of the driving gear 1 and the driven gear 2 is reduced, and the life can be extended and the pump operation can be achieved also here. Due to the effect of reducing the load torque, the electric motor 11 can be downsized. An example of the correlation between the amount of tetrafluoroethylene resin added and the dynamic friction coefficient is shown in FIG.

Further, it has a function of preventing adhesion of scale components such as calcium ions in water, and can prevent rotation of the driving gear 1 and the driven gear 2 from being locked, and can be used for transporting tap water.

[0021]

As described in the above embodiments, the present invention is
A case in which a driving gear, a driven gear, and two gears are housed,
The gear pump is configured with a base that closes the case, and each component is formed by injection molding of a material in which PPS resin is mixed with carbon fiber, ethylene tetrafluoride resin, and zinc oxide whiskers. (1) Zinc oxide whiskers reduce the anisotropy of molding shrinkage to stabilize the molding size, prevent abnormal wear due to friction between the gear and the case due to poor shape, and reduce the dynamic friction by tetrafluoroethylene resin. Wear can be prevented when the gears are meshed. Therefore, the life can be extended. (2) Since the molding dimension is stable with high accuracy, the sliding gap between the gear and the case can be set small and pump efficiency can be improved. (3) The operation noise can be reduced by the damping effect of the zinc oxide whiskers. (4) Pump rotation load torque is reduced due to the effect of reducing dynamic friction, so the electric motor can be made even smaller and less expensive. (5) The rotation lock of gears can be prevented by the action of preventing scale accumulation in water.

As described above, it is possible to provide a gear pump having low noise and high reliability.

[Brief description of drawings]

FIG. 1 is a sectional configuration diagram of a gear pump according to an embodiment of the present invention.

FIG. 2 is a sectional view of the liquid passage portion of the gear pump taken along the line AA in FIG.

[Fig. 3] Correlation diagram between the amount of tetrafluoroethylene resin added and the dynamic friction coefficient

[Explanation of symbols] 1 driving gear 2 driven gear 3 case 4 base

Claims (2)

[Claims] 1. A pair of gears, a case that houses the gears, and a base that closes the case. The gears, the case, and the base are made of polyphenylene sulfide resin, carbon fibers, and tetrafluoroethylene resin. A gear pump formed by injection molding a resin material containing zinc oxide whiskers. 2. The ratio of each component of the material of the gear, the case and the base is 40 to 60% by weight of polyphenylene sulfide resin, 10 to 30% by weight of carbon fiber, 5 to 20% by weight of tetrafluoroethylene resin and 5 of zinc oxide whisker. ~ 20% by weight
The gear pump according to claim 1, wherein