JPH10220363A - Sealing method for rotary volume type pump and rotary volume type pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform delicate regulation of a leak amount by inserting and fixing a bush provided with an inner taper cylinder part in a shaft, leaving a slight gap between a side plate through-hole and the bush, and inserting a seal ring provided with an outer taper cylinder part positioned axially facing the bush with a slight gap therebetween. SOLUTION: When, in a gear pump for extrusion-molding plastic, a shaft 3 is rotated, a bush 10 at which an inner taper cylinder part is formed is rotated together with a shaft 3. Molten resin flows in a space V through a gap G1 between a side plate through-hole 5a and a bush cylinder part and a gap G2 between a large diameter part and the bush cylinder part, and further, and flows in a gap G4 between an inner taper cylinder part and the outer taper cylinder part of a seal ring 20. When a leak amount flowing through the gap G1 is increased, a large part is bent toward the inner side in a radial direction and the gap G2 is increased. When leak flowing through the gap G4 part is increased, the large part is bent toward the outside in a radial direction and moved in a direction in which the gap G2 is decreased. This constitution controls the leak to a specified value.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotary displacement pump such as a gear pump and a screw pump.

[0002]

2. Description of the Related Art Gear pumps for plastic extrusion are exposed to high temperatures and high pressures compared to general pumps. Therefore, there is no suitable packing for preventing leakage from the through shaft, and usually a minute gap is provided. The reality is that some amount of leakage is allowed. The most frequently used sealing method is to provide a fine spiral groove on the inner surface of the seal ring, and to operate the spiral groove so that the leaked liquid flows back from the outside to the inside by rotating the shaft, thereby reducing the amount of leakage from the pump. I try to reduce it. Further, the cooling jacket lowers the temperature in the vicinity of the shaft, solidifies the leaked molten resin to a certain extent, and has a function of suppressing the amount of leakage.
FIG. 5 shows a configuration in which a gap G between the seal rings A and B facing in the axial direction can be adjusted during operation by an external adjustment screw C.

[0003]

However, these conventional techniques have the following problems. That is, since it is better that the leakage is as small as possible, the gap may be reduced as much as possible. However, if the gap is too small, metal contact with the rotating portion occurs, and a so-called seizure phenomenon occurs.
Causes problems such as heat generation and shutdown. The operating conditions of the pump vary from time to time. That is, the viscosity and pressure of the internal fluid change depending on the change in the number of revolutions, the temperature, the pressure, and the type of the raw material, which are transmitted to the shaft clearance. Therefore, if the gap is fixed minutely under certain conditions, the above change cannot be accommodated, causing an abnormal pressure rise, which may hinder operation. To adjust this, the pump must be stopped and the leak adjusted by modifying or replacing the seal ring.

In the method of solidifying the resin in the gap by the cooling jacket, the volume of the gap is very small.
A slight change in temperature causes the resin in the gap to become unstable, causing the resin to adhere to the shaft or increase leakage. In addition, since there is no method for measuring the temperature of the gap, there is no recording or reproducibility since the temperature control by the cooling jacket is performed only by visually checking the state of the resin in the gap.

On the other hand, in the method of adjusting the gap by moving the seal ring with an adjusting screw, the amount of resin leakage is controlled only by the size of the axial gap G between the seal rings A and B. Contact (when the gap is too small) or large leakage (when the gap is large)
Easily.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and to provide a method of sealing a rotary displacement pump and a rotary displacement pump capable of minimizing fluid leakage and finely adjusting the amount of leakage.

[0007]

Means for Solving the Problems To solve the above problems, the configuration of the present invention is as follows. That is, in the method of the first configuration, in a rotary positive displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft, the shaft is concentric with the shaft. A bush having an inner tapered cylindrical portion tapering inward in the direction is inserted and fixed to the shaft, leaving a slight gap between the side plate through-hole and the shaft facing the bush in the axial direction,
Insert a seal ring having an outer tapered tube portion leaving a slight gap, slidably fit into the hole of the side plate, and overlap a part of the bush inner tapered tube portion in the axial direction. In the vicinity of the axially outer end of the bush, the thickness in the radial direction is determined to be thin so that the bush can be slightly elastically deformed in the radial direction by the difference between the fluid pressures on the radially inner side and the outer side. Move in the axial direction,
This is to adjust the gap between the overlapping portions of the tapered surface.

[0008] In the method of the second configuration, in a rotary displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft, the rotating body is concentric with the shaft. A bush having an inner tapered cylindrical portion tapering inward in the axial direction is inserted into and fixed to the shaft, leaving a slight gap between the bush and the side plate through-hole. , A seal ring having an outer tapered tube portion is inserted with a slight gap left therebetween, slidably fitted in the hole of the side plate, and overlapped with the inner tapered tube portion of the bush in a partial section in the axial direction. In the vicinity of the axially outer end of the bush, the thickness in the radial direction is set to be thin so that the bush can be slightly elastically deformed in the radial direction by the difference between the fluid pressures on the inner side and the outer side in the radial direction. Move in the axial direction A ring-shaped space larger than the gap between the overlapping portions is formed outside the overlapping portion in the axial direction, the fluid is temporarily stored in the space to cool the space, and the temperature of the fluid in the space is detected. The amount of the cooling medium in the cooling jacket of the seal ring is adjusted, and / or the position of the seal ring in the axial direction is adjusted, so that the fluid in the space becomes a semi-solid solution.

A third configuration is a rotary positive displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft. A bush in which a gap is interposed between the side plate through-hole and an inner tapered cylindrical portion that becomes thinner inward in the axial direction, and a gap in the shaft that faces the bush in the axial direction. A seal ring having a flange portion formed outside the outer tapered tube portion that is slidably fitted into the hole of the side plate and overlaps with the inner tapered tube portion of the bush; Adjusting means for moving and fixing the bush in the axial direction, a gap is left in the overlapping portion between the bush and the seal ring, and the vicinity of the axially outer end of the bush is radially inward and outward. Of fluid pressure Accordingly, as in the radial direction can be slightly elastically deformable, it is that the radial thickness is thin.

A fourth structure is that, in addition to the third structure, a ring-shaped space larger than the gap between the overlapping portions is left outside the bush in the axial direction.

The fifth configuration is, in addition to the third or fourth configuration,
A measurement hole is provided from the outer peripheral surface of the side plate toward the ring-shaped space, a thermometer is inserted into the measurement hole, and a cooling jacket is provided on the seal ring.

[0012]

[Action] molten resin flows through the gap G ₁ part of the side plate and the bush, the amount of leakage there is increased, increases the pressure of the portion, as a result, the leading end portion of the bushing results in a deflection radially inward. Further, when the leakage through the gap G ₄ parts between the tapered surfaces increases rises pressure of the portion, the distal end portion of the bush occurs a deflection radially outward, move in the direction to reduce the gap between the side plates. In this manner, the tip of the bush repeatedly elastically deforms inward and outward in the radial direction within a certain constant pressure to control the leakage to a constant amount. Further, since the seal ring is cooled by the cooling medium of the cooling jacket, the molten resin in the space V touching the seal ring is cooled and solidified to an appropriate hardness to form a ring, which itself functions as a packing material.
Further, since the bush and the seal ring form a tapered gap, the amount of change in the taper interval with respect to the axial movement of the seal ring is reduced by operating the adjusting means, and the gap can be finely adjusted.

Some leakage of the semi-solid solution from the resin ring is discharged to the outside from around the shaft. The temperature of the resin ring is adjusted to an appropriate temperature by detecting the temperature with a thermometer and adjusting the cooling medium to the cooling jacket.
, Always forms a similar semi-solid solution ring to provide a sealing effect.

[0014]

Embodiments of the present invention will be described below based on an embodiment of a gear pump shown in the drawings. FIG.
, A gear 2 is rotatably supported in a case 1 via a shaft 3 and a bearing 4, and a side plate 5 is fixed to the case 1 through the shaft 3.

The bush 10 is inserted through the shaft 3 so as to be concentrically fixed, and is interposed with a through hole 5a of the side plate 5 with a gap. The bush 10 has an inner tapered cylindrical portion 12 formed concentrically at the tip (facing outward of the pump) of the cylindrical portion 11. The inner circumferential surface of the inner tapered tube portion 12 becomes a tapered surface 12a that becomes thinner in the axial direction (the inside of the pump is referred to as the inside and the outside of the pump is referred to as the outside), and the shaft 3 passes through the shaft center. It has a center hole 10a. Then, it is fixed to the shaft 3 by a set screw 6 penetrating in the radial direction from the outer circumferential surface of the cylindrical portion 11.

The thickness of the bush 10 near its axially outer tip is reduced in the radial direction so that it can be slightly elastically deformed in the radial direction due to the difference in fluid pressure between the radially inner and outer sides. ing. That is, the axial end portion (the inner tapered surface 12a) of the inner tapered cylindrical portion 12 of the bush 10
Is formed into a large-diameter portion 12b via a step, and a circumferential groove 12c is formed at the boundary portion.
Is provided. At the portion of the circumferential groove 12c, the thickness of the bush 10 in the radial direction is reduced, so that the bush 10 can be elastically deformed.

A seal ring 20 is inserted through the shaft 3 with a gap in the shaft 3 so as to face the bush 10 in the axial direction.
And it is slidably fitted in the through hole 5a of the side plate 5. The seal ring 20 is formed by forming a cylindrical portion 22 via a step on the outside in the axial direction of an outer tapered tube portion 21 overlapping the inner tapered tube portion 12 of the bush, and a flange portion 23 on the outside thereof. The outer circumferential surface of the outer tapered cylindrical portion 21 is a tapered surface 21a that is tapered inward in the axial direction so as to match the inner tapered surface 12a of the bush.
Has a central hole 20a that penetrates. Also, seal ring 2
0 is provided with a cooling jacket 24 through which cooling water passes.
A plurality of threaded rods 7 as adjusting means for moving and fixing the seal ring 20 in the axial direction penetrate the flange 23 of the seal ring at equal intervals on the same circumference centered on the shaft 3 and pass through the side plate 5. Screwed into.

As shown in FIG. 2, a gap G ₁ and a large-diameter portion 12 between the side plate through hole 5a and the bush cylindrical portion 11 are formed.
gap G ₂ is left respectively between the b. In the axially outside of the overlapping portion of the tapered surfaces 12a and 21a, the tapered cylindrical portion 12 in the bush and the seal ring cylindrical portion 2
A ring-shaped space V (an axial gap G ₃₁ and a radial gap G ₃₂ ) is left at the end face of the second and the portion surrounded by the side plate through-hole 5a. Further, the inner and outer tapered cylindrical portions 12, 21
Gap G ₄ between the tapered surfaces of the seal ring central aperture 10
slight gap G ₅ is left between the a inner surface and the shaft 3.

A measurement hole 5b is provided from the outer peripheral surface of the side plate 5 toward the ring-shaped space V, and a thermometer 8 is inserted into the measurement hole 5b.

The operation state will be described above. When the shaft 3 is rotated, the bush 10 rotates together with the shaft 3. The molten resin passes through the gap between the shaft 3 and the bearing 4 from the case 1,
Further, the space V enters the space V through the gaps G ₁ and G ₂ , and further enters the space G ₄
Come in. When the amount of leakage through the gap G ₁ part increases,
Since G ₁ > G ₂ , the pressure at that portion increases, and as a result, the large-diameter portion 12 b bends radially inward, and G ₂ expands. Further, when the leakage through the gap G ₄ parts increases to increase the pressure of that portion is moved in a direction in which the large-diameter portion 12b to reduce the G ₂ cause deflection radially outward. in this way,
The large-diameter portion 12b repeatedly elastically deforms inward and outward in the radial direction within a certain constant pressure to control the leakage to a constant amount.

Further, since the seal ring 20 is cooled by a cooling medium (water, oil, air, etc.) of the cooling jacket 23, the molten resin in the space V touching the seal ring 20 is cooled and solidified to an appropriate hardness to form a ring. And acts as a packing material by itself. That is, if leaked fluid from the gear side enters the semi-solid solution ring, it does not immediately exit. Since the ring is resilient, leaks from the high pressure side
The ring is compressed and pressed against the outflow side to perform a sealing function. If the pressure rises to some extent, the leak will go out of the ring. In this way, it acts as a packing.

Further, since the bush 10 and the seal ring 20 to form a tapered gap G _4, by operating the adjusting screw 7, the gap distance variation relative amount of axial movement of the seal ring is reduced, the gap Can be finely adjusted.

Some leakage of the semi-solid solution from the resin ring is released to the outside through the gaps G ₄ and G ₅ . Thermometer 8
, The temperature of the resin ring is adjusted to an appropriate temperature by adjusting the cooling water to the cooling jacket 24, and
The resin pool formed by the ring-shaped space V always forms the same semi-solid solution ring, and performs a sealing action.

FIG. 3 shows another embodiment.
A circumferential groove 12d is provided substantially in the axial half of 2a, and the portion between the circumferential groove 12d and the step on the outer peripheral surface is thinned.

FIG. 4 shows still another embodiment, in which a thin cylindrical portion 12e having an inner cylindrical surface extending to the tip is formed following the inner tapered surface 12a, and a boundary between these boundaries and a step on the outer peripheral surface is formed. It becomes thin between, and deforms radially inward and outward around this portion. In the seal ring 20, a second cylindrical portion 25 concentric with a small gap is formed between the outer tapered cylindrical portion 21 and the first cylindrical portion 22 inside the thin cylindrical portion 12e.

Table 1 shows an example of the numerical values of the ring-shaped space V and the gaps of each part.
It is as follows. Therefore, the size of the space V is G ₃₁ = 3
２５25 mm and G ₃₂ = 3 to 25 mm are suitable, and among them, G ₃₁ = 5 to 15 mm and G ₃₂ = 5 to 15 mm are more preferable.

The present invention is applied to a rotary positive displacement pump such as a gear pump, a screw pump, a vane pump, a cam pump, and the like.
Suitable for various fluids of large viscosity such as adhesives.

The present invention is not limited to the embodiments and embodiments described above, but includes various modifications without departing from the spirit and scope of the appended claims.

[0029]

According to the configuration of the present invention, the leakage of the fluid is kept substantially constant due to the elastic deformation particularly in the vicinity of the tip of the bush. Further, by monitoring the thermometer and adjusting the amount of the cooling medium to the cooling jacket, the temperature of the resin reservoir V can be kept constant, and the resin in this portion can be used as a packing to form an appropriate semi-solid solution. Therefore there is no need to so much regulation of the gap G ₄ ~G ₅ subtle. When the overlapping portion between the seal ring and the bush has a tapered surface, the gap in the tapered surface can be finely adjusted by moving the seal ring in the axial direction.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of one embodiment of the present invention.

FIG. 2 is an explanatory diagram of a gap near an axis.

FIG. 3 is a vertical sectional view of a main part of a second embodiment of the present invention.

FIG. 4 is a vertical sectional view of a main part of a third embodiment of the present invention.

FIG. 5 is a vertical sectional view of a conventional technique.

[Explanation of symbols]

 G Gap V space 1 Case 2 Gear 3 Shaft 4 Bearing 5 Side plate 5a Through hole 5b Measurement hole 6 Set screw 7 Adjustment screw 8 Thermometer 10 Bush 10a Center hole 11 Cylindrical part 12 Inner tapered cylinder part 20 Seal ring 20a Center hole 21 Outer Tapered tube part 22 Cylindrical part 23 Flange part 24 Cooling jacket

[Table 1]

Claims (5)

[Claims] 1. A rotary displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft. A bush having an inner tapered tube portion is inserted through and fixed to the shaft, leaving a slight gap between the bush and the side plate through-hole. Through the seal ring having a slight gap, and slidably fitted into the hole of the side plate, and overlapped in a part of the inner tapered cylindrical portion of the bush in the axial direction. In the vicinity of the axially outer tip, the thickness in the radial direction is determined to be thin so that it can be slightly elastically deformed in the radial direction by the difference between the fluid pressures on the radially inner and outer sides, and the seal ring is moved in the axial direction. Let the taper Method of sealing a rotary displacement pump, characterized by adjusting the gap of the overlapping portion. 2. A rotary positive displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft. A bush having an inner tapered tube portion is inserted through and fixed to the shaft, leaving a slight gap between the bush and the side plate through-hole. Through the seal ring having a slight gap, and slidably fitted into the hole of the side plate, and overlapped in a part of the inner tapered cylindrical portion of the bush in the axial direction. In the vicinity of the axially outer tip, the thickness in the radial direction is determined to be thin so that it can be slightly elastically deformed in the radial direction by the difference between the fluid pressures on the radially inner and outer sides, and the seal ring is moved in the axial direction. And the polymerization section The outward, the polymerization unit atmospheric made to form a ring-like space from the gap of the fluid cooled temporarily to Todokotamari to the space,
The temperature of the fluid in the space is detected to adjust the amount of the cooling medium in the cooling jacket of the seal ring, and / or the axial position of the seal ring is adjusted to make the fluid in the space a semi-solid solution. A method for sealing a rotary displacement pump. 3. A rotary displacement pump in which a rotating body is rotatably supported in a case via a shaft and a bearing, and a side plate is fixed to the case through the shaft, wherein the side plate is fixed concentrically to the shaft. A bush in which an inner tapered cylindrical portion which is narrowed inward in the axial direction is formed with a gap between the through hole and the bush; and a gap is formed in the shaft so as to face the bush in the axial direction. A seal ring which is inserted and slidably fitted into the hole of the side plate, and has a flange formed outside the outer tapered tube portion overlapping with the inner tapered tube portion of the bush; Adjusting means for moving and fixing the bush, a gap is left in the overlapping portion of the bush and the seal ring, and the vicinity of the axially outer end of the bush is near the radially inner and outer fluid pressure Depending on the difference As in the radial direction can be slightly elastically deformable, rotating displacement pump, wherein the radial thickness is thin. 4. The rotary displacement pump according to claim 3, wherein a ring-shaped space larger than a gap between the overlapping portions is left outside the bush in the axial direction. 5. A measurement hole is provided from an outer peripheral surface of the side plate toward the ring-shaped space, a thermometer is inserted into the measurement hole, and a cooling jacket is provided on the seal ring. The rotary positive displacement pump according to claim 3 or 4.