JPS5853688A - Gear pump - Google Patents

Abstract

PURPOSE:To prevent the enclosing phenomenon of the engaging portion by allowing a pair of gear provided on the inside and outside of a casing respectively to share a pumping action and a driving force transmitting action and by engaging the inside pumping gear in a non-contact condition. CONSTITUTION:A pumping action and a driving force transmitting action are shared by a pair of pumping gears 1, 1' provided on the inside and outside of a casing respectively through driving gears 4, 4', and both gears 1, 1' inside the casing 2 are engaged together in a non-contact condition with a clearance C. Accordingly, both pumping gears 1, 1' serve for only a pump feed mechanism, and the driving force transmitting function interlocking both gears 1, 1' is performed by only the driving gears 4, 4', thereby no such remarkable restriction on the size, shape, etc. is inflicted for production as in the case both functions are shared by a pair of gears. Furthermore, the clearance C between both gears 1, 1' gives a relief area to the material 11, thus the enclosing phenomenon can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gear pump particularly suitable for the delivery of highly viscous materials.

Recently, it has been proposed to use a gear pump, which is smaller and has a simpler structure than a screw extruder, as a means of extruding a polymer material melted in a mixer or the like and sending it to a die or injection molding machine. There were the following problems.

In other words, in a gear pump that generally consists of a pair of gears that mesh with each other and a casing that surrounds both gears, the moment required by both gears is the moment relative to the central axis of the force generated at the top of the tooth of the gear, and the moment generated at the side surface of the tooth. The moment of the force generated in other parts of the gear with respect to the central axis, the moment of the force generated between the gear shaft and the bearing with respect to the central axis, etc. are added. The moment is related to the viscosity of the material being pumped, and the gear drive power is approximately proportional to the material viscosity. Therefore, the driving power of the gear pump becomes large in order to feed a polymeric material whose viscosity is much higher than that of water, oil, etc. By the way, in conventional gear pumps for pumping water, oil, etc., a pair of mutually meshing gears inside the casing are used for both pumping and driving force transmission. When sending concentrated materials,
In terms of the pump feeding function, the material can be fed more efficiently when the gear is rotated at low speeds, so it is desirable to have a rotation speed of several tens to 100 revolutions per minute.On the other hand, at such low rotation speeds, the shear force increases. Since the viscosity of the material tends to increase due to a decrease in the viscosity of the material, the torque increases, and the role of the pump and the role of the driving force transmission are contradictory. For this reason, it is necessary to increase the strength of the gear itself, and the hardness of the tooth surface must be extremely high, making it easy to cause problems if foreign matter contained in the material being pumped gets caught between the gears. However, it requires high precision, is expensive, and has short lifespan. In addition, gear pumps have a basic structure of simply meshing a pair of gears.
A problem called so-called confinement occurs. As shown in Figure 1, when a pair of gears G1162 mesh, they meet at two points P and Q, and the material is trapped in the sealed space A between them, and at the time when the confinement starts as shown in Figure 1 (a). Same as (b
) The volume of the sealed space A gradually changes between the middle point of confinement shown in (C) and the end of confinement shown in (C), causing a large pressure change in the material confined in the space A. However, this phenomenon is a hindrance to gear pumps and has a negative impact on quality when used with polymeric materials. Conventionally, as a solution to this entrapment, it is known to provide each gear with an escape groove so that it communicates with the sealed space A, or to use a single helical or double helical gear for each gear.

However, with the former method, materials are held up in the relief groove,
In particular, with high viscosity polymeric materials, there is a risk of quality deterioration within the relief groove, and the latter method produces thrust force when using a single helical gear, and difficulty in manufacturing teeth contact when using a double helical gear. In addition, no matter what method you use, problems caused by foreign matter biting into the contact area of the teeth cannot be eliminated, making it not very effective as a gear pump used for highly viscous materials. There wasn't.

In view of these circumstances, the present invention shares the pumping action and the driving force transmission action between a pair of gears provided inside the casing and a pair of gears provided outside the casing. By making gears mesh in a non-contact manner, the drawbacks of conventional gear pumps are overcome, and a gear pump that can be effectively used for highly viscous materials is provided. Furthermore, by using the present invention, when the pumping gear is a single helical gear, the driving gear is a single helical gear with the helical angle reversed, so that the thrust forces of both gears cancel each other out, and the single helical gear is used. It also prevents the generation of thrust force, which is a drawback when using helical gears.

The invention will now be explained by means of illustrative implementations.

2 and 6 schematically show the overall structure of the gear pump of the present invention. In these figures, 1 and 1' are a pair of pumping gears arranged in meshing positions, and 2 is a pair of pumping gears 1 and 1'. , 1, and 6' are rotating shafts integrally connected to both gears 1 and 1', and 4 and 4 are drive gears disposed outside the casing 2 and meshing with each other. .

The casing 2 has a material intake port 5 on the upper side and a material outlet port 6 on the lower side, and the inner surfaces of the front and rear walls are in close contact with both axial end surfaces of the pumping gears 1, 1 to maintain a sealing state. , the inner surfaces of both side walls of the outer periphery of the pumping gears 1 and 1' are shaped so that they partially slide over the tips of the teeth ◇If the viscosity of the material to be pumped is high, the intake port 5
Since the material supplied onto both pumping gears 1, 1 from the above does not enter the tooth groove immediately, there are tooth tips and tooth tips on the inner surface of the casing 2 corresponding to the outer periphery of the gears 1, 1' at a location near the outlet 6. With the sliding contact parts 7, 7' remaining, undercut parts 8, 8' are preferably provided on the upstream side to form a space for the material to easily enter the tooth groove as it moves. .

a rotary shaft filter connected to each of the pumping gears 1, 1;
6' are rotatably supported by the casing 2 via bearings 9, respectively, and one end side of each of the two rotating shafts 6, 3 protrudes outside through the casing 2, and the drive shaft is attached to this protruding portion. Gear 4.4 is installed.

The two gears 4, 4 are in a completely meshed state in which they contact each other at their meshing portions, similar to the meshing state of general gears. In addition, both the rotation shafts 6. One of the rotating shafts 6 is connected to the motor 0 as a drive source via a reducer (not shown), and the rotation of the rotating shaft 6 is up!
!
By being transmitted to the other rotating shaft 6 via both driving gears 4, 4, both rotating shafts 6, 6', and thus both pumping gears 1, 1, are rotated synchronously. The direction of rotation is similar to a general gear pump of this type, as shown by the arrow in FIG. 1 and 1' to the downstream side.

FIG. 4 shows an enlarged view of the meshing portion of the two pumping gears 1, 1', and as shown in the same figure, the two pumping gears 1, 1' are engaged with each other. ;' is formed so that although there is a meshing shape in which one tooth enters the groove of the other tooth, the teeth do not always touch each other and there is a slight clearance C even where the teeth are closest to each other. It is.

The operation of this gear pump will be explained next.

The action of pumping fluid material is basically the same as that of a general gear pump of this type, and the material sent into the casing 2 from the intake port 5 is pumped through both pumping gears 1.
, 1', it is guided in the outer circumferential direction while entering the tooth groove, and is sent downstream along the inner surface of the casing 2. Then, the tooth tip of each pumping gear 1, 1' and the casing 2
Communication between the upstream side and the downstream side is cut off at the sliding contact portions 7, 7 with the inner surface, and the material held in the tooth grooves of the gears 1, 1 is quantitatively sent to the outlet 6 side. In this case, the material is transferred to the outlet 6
In order to quantitatively extrude the material at a constant pressure from the casing 2, it is necessary that both gears 1 and 1 mesh with each other at the center of the casing 2 to have the effect of extruding the material from the tooth groove. Even though gears i, i, and ' are in a negative contact state, they are in a meshing state where one tooth enters the tooth groove of the other, and because the clearance is small and the viscosity of the material is high, a backflow occurs from the outlet side to the inlet side. The quantity is small and therefore the extrusion force is obtained.

In this operation, both pumping gears 1.1 are responsible only for the pump feeding mechanism, and the driving force transmission function for interlocking the two gears 1.1 is performed by the driving gear 4.4. The design and manufacture of each gear become easier without being subject to significant manufacturing constraints regarding dimensions, shapes, etc., unlike when gears share both functions.

In addition, since the pumping gear 1.1 does not require contact meshing for driving force transmission, by appropriately shaping the tooth width, meshing depth, etc., meshing can be achieved as shown in Fig. 4. A situation is obtained in which the two pumping gears 1.1 do not come into contact with each other. By maintaining the non-contact state, the clearance between the two gears 1.1 provides an escape area for the material 11, and the above-mentioned entrapment phenomenon can be avoided. However, in this case, there is a concern that some material will leak from the downstream high-pressure side to the upstream low-pressure side through the above clearance, and this will reduce the discharge efficiency slightly, but as long as the clearance is sufficient, it can does not cause any practical problems. In other words, when calculating the leakage amount Q for a certain section of the meshing part shown in Fig. 4 (assuming that the material is Newtonian fluid), the gear width is b1 the average clearance is T1゛ the pressure between the upstream side and the downstream side If the difference is p1 and the viscosity is η, then the following equation is obtained.

T3p Therefore, if the viscosity of the material is relatively high and the clearance is small, the amount of leakage can be suppressed to a sufficiently small level, and the pump function will not deteriorate. For example, if LDPE is used as the material to be pumped, the pressure difference p is 300 kg/c.
When the minimum clearance of both pumping gears 1 and 1' is varied as ++t, the pump function is 99.8% with [T2 100μ] compared to a contact mesh type gear.
to 985% at (T=200μ), I:'T=300
μ] and 88% respectively.

This slight decrease in pumping function can be compensated for by increasing the rotation speed of the gear a little.
There is no problem such as failure of necessary pressure to be generated on the outlet port 6 side.

Furthermore, since there is a clearance between the two pumping gears 1, 1', even if foreign matter with a diameter smaller than this clearance gets mixed in, the gear 1.1' will not be damaged.

In addition, as mentioned above, the minimum clearance C between the teeth of both pumping gears 1.1' is 100μ as a range that can prevent the entrapment phenomenon and sufficiently compensate for the decrease in pump function by adjusting the rotation speed. It is desirable to set it in the range of ~1000μ.

Additionally, a helical gear may be used as the pumping gear, and if a single helical gear is used, these thrust forces can be reduced by using a single helical gear for the driving gear, whose thrust force is opposite to that of the pumping gear. As described above, in addition to the pair of pumping gears disposed inside the casing, the gear pump of the present invention has a rotating shaft connected to each of the pumping gears outside the casing. The driving gears are installed to completely mesh with each other, and the pumping gears are formed so that they have a clearance above a certain level without contacting each other even at the meshing portions, so that the pumping gear and the driving gear are not in contact with each other. The pumping function and driving force transmission function are shared between the screaming gear and the dimensions and shape settings of each gear, etc., which improves manufacturability, durability, etc., and provides good pumping function for highly viscous materials. However, due to the existence of the above-mentioned clearance, it is possible to prevent the entrapment phenomenon in the meshing part of the pumping gear, but it also prevents the disadvantages such as material retention and manufacturing difficulties that are seen in conventional entrapment countermeasures. Furthermore, even if foreign matter gets mixed in, the pumping gear will not be damaged, and has many excellent effects.

[Brief explanation of drawings]

1(a) to 1(C) are explanatory diagrams showing the confinement phenomenon in the basic structure of a conventional gear pump, FIG. 2 is a schematic cross-sectional view showing an embodiment of the gear pump of the present invention, and FIG. 6 is a sectional view taken along the line III--III in FIG. 2, and FIG. 4 is an enlarged view of the meshing portion of the pumping gear in this gear pump. 1.1'... Pumping gear, 2... Casing, 6.6'... Rotating shaft, 4.4'... Drive gear. 1.5 Applicant: Kobe Steel, Ltd., Patent Attorney: Etsushi Kotani. Figure 1 (a) (''))) (C) Figure 2 Opening■ Figure 4

Claims (1)

[Claims] 1. In a gear pump having a pair of pumping gears disposed in meshing positions with each other and a casing surrounding the two gears, two rotating gears respectively connected to each of the pumping gears are provided. A pair of driving gears that completely mesh with each other are disposed in the part where the shaft penetrates the casing and protrudes to the outside, so that the rotation of one rotational shaft driven by the drive source is transferred to the other through the two driving gears. Both rotating shafts are interlocked so as to transmit information to the rotating shaft of the pumping gear, and both pumping gears are formed so that the teeth do not come into contact with each other and have a clearance above a certain level even in the meshing portions. gear pump. 2. The teeth according to claim 1, characterized in that the clearance at the part where the teeth of both pumping gears are closest to each other is 100μ to 1000μ [1 (pump). 6. The pumping gear The gear pump according to claim 1, wherein the driving gear is a single helical gear and the thrust force is in the opposite direction to that of the gear.