JPH0727427Y2 - Gear pump - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention 1) Field of Industrial Application The present invention relates to a gear pump, and particularly in the case of producing a high-molecular polymer such as a synthetic resin, the degree of polymerization per reaction container It relates to a gear pump suitable for use in transferring different liquid intermediate products to the next reaction vessel.

2) Conventional Technology Conventionally, in a chemical plant or the like for producing a high-molecular melt polymer, as shown in FIG. 6, a liquid intermediate product having a different degree of polymerization for each reaction vessel V1, V2, ... Gear pumps G1, G2, ... Are used when sequentially transferring to the next reaction vessel. These gear pumps G1, G2, ... Are driven by a gear drive motor (not shown) via a universal joint or the like. The viscosity of the transferred liquid intermediate product increases as the manufacturing process progresses from the initial process (solution), the intermediate process (prepolymer) and the final process (polymer). Therefore, the gear pumps G1, G2, ... Use those adapted to each of the above steps.

When the operation of the chemical plant as described above is started (startup), it is normally operated continuously for one year or more. Then, after being operated for a certain period of time, the operation is stopped (shutdown) and the parts of the gear pump and the like are overhauled.

In such a chemical plant, the liquid raw material supplied to the reaction vessel V1 immediately after startup is the reaction vessel V1.
After being reacted to some extent inside to become a liquid intermediate product, it is transferred by the gear pump G1. Part of the intermediate product transferred by the gear pump G1 is circulated in the reaction container V1, and the other part is transferred in the reaction container V2. Other reaction vessels V2, V
3 (not shown), ... and gear pumps G2, G3 (not shown), ... Are used similarly to the reaction vessel V1 and the gear pump G1.

As described above, the intermediate product delivered from the reaction vessel V1 is partly circulated and returned to the reaction vessel V1 to allow the reaction to proceed, so that the viscosity gradually increases. Then, when a steady state is reached after a lapse of a predetermined time from the startup, the viscosity is kept within a predetermined range. Also, at the time of the shutoff,
Shut off after gradually reducing the viscosity of the transfer fluid. Therefore, the viscosity of the fluid transferred by the gear pump G1 is from 0.8 cp (centipoise) to 300-500 poise.
(Poise) A big change.

(3) Problems to be Solved by the Invention By the way, conventionally, a mechanical seal and a gland packing are used as a shaft sealing structure of a gear pump. If the viscosity changes significantly,
It is better to use a mechanical seal. However, the mechanical seal has a complicated structure and is expensive. In addition, the shaft seal structure that uses the gland packing uses a gland packing that is suitable for the viscosity of the transfer fluid in the steady state (for example, 300 to 500 poise), and when transferring low viscosity fluid at startup or when the shaft is off. In addition, there is a problem that a large amount of fluid leaks.

In view of the above-mentioned circumstances, the present invention is a gear pump having a shaft sealing structure using a gland packing, and the viscosity of the transfer fluid in a steady use state (for example, 300 to 500 poise).
Even when using a gland packing suitable for, when transferring low-viscosity fluid at startup or shutoff,
An object is to prevent a large amount of fluid leakage.

B. Configuration of the Invention (1) Means for Solving the Problem In order to solve the above problems, a gear pump of the invention comprises a driven shaft carrying a driven gear and a drive shaft carrying a drive gear meshing with the driven gear. A bearing for rotatably supporting the driven shaft and the drive shaft is housed inside the case body,
A stuffing box having a gland packing receiving hole through which the drive shaft penetrates and a gland packing is stored is disposed on the front side of the case body, and the gland packing is pressed against an inner end of the gland packing storing hole and the gland is held. A gear pump in which a packing presser having an inner peripheral surface of a packing accommodating hole and a sealing surface in contact with the outer peripheral surface of the drive shaft is arranged around the drive shaft, wherein the drive has an inner end surface facing the outer end surface of the packing presser. A seal collar movable in the axial direction of the shaft is arranged so as to rotate integrally with the drive shaft.

The term "outer peripheral surface of the drive shaft" means the "outer peripheral surface of the shaft sleeve" when there is a shaft sleeve or the like connected to the outer periphery of the drive shaft so as to rotate integrally with the drive shaft. Shall mean.

(2) Operation When the gear pump of the present invention having the above-mentioned configuration is started up using the gland packing suitable for the high-viscosity fluid transferred in the steady state, the low-viscosity fluid transferred first is the gland packing. Will easily pass through and will leak to the outside of the gear pump. However, the low-viscosity fluid that has passed through the gland packing is sealed by the sealing surface of the packing retainer that is in contact with the inner peripheral surface of the gland packing accommodating hole and the outer peripheral surface of the drive shaft, and does not leak to the outside.

After that, when the gear pump continues to operate, the drive shaft continues to rotate, but the stuffing box and packing retainer do not rotate and are held stationary. Therefore,
Since the inner peripheral surface of the gland packing housing hole of the stuffing box and the seal surface of the packing retainer which is in contact with this inner peripheral surface do not move relative to each other, the sealing function of that portion hardly deteriorates. However, the outer peripheral surface of the drive shaft and the sealing surface of the packing presser, which is in contact with the outer peripheral surface, move relative to each other, so that the sealing function of that portion gradually deteriorates.
However, when the sealing function between the outer peripheral surface of the drive shaft and the sealing surface of the packing presser contacting the outer peripheral surface deteriorates, the gear pump is in a steady operation, and the viscosity of the transferred fluid becomes high. There is. Therefore, since the amount of fluid passing through the gland packing is small, the amount of fluid that leaks does not increase even if the sealing function deteriorates.

When the gear pump is continuously operated for a long period of time and then shut down, the viscosity of the transfer fluid is gradually decreased to finally reach a viscosity of about water, but the gear pump is stopped at an appropriate viscosity. Then, a seal member is wound around the drive shaft surface between the outer end surface of the packing retainer and the inner end surface of the seal collar that faces the packing presser, and the seal collar is moved in the axial direction of the drive shaft. Then, the wound seal member is sandwiched between the outer end surface of the packing retainer and the inner end surface of the seal collar.

When the viscosity of the transfer fluid is lowered in this state, the transfer fluid of low viscosity passes through the gland packing, and the outer peripheral surface of the drive shaft having the deteriorated sealing function and the packing presser contacting the outer peripheral surface. It tries to leak to the outside of the gear pump by passing between it and the sealing surface. However, the low-viscosity fluid that is about to leak to the outside of the gear pump is prevented from leaking by the seal member that is wound around the surface of the drive shaft.

(3) Embodiment An embodiment of the gear pump according to the present invention will be described below with reference to the drawings.

1 to 5, a circumscribed gear pump G that sucks fluid from the direction of arrow A1 and discharges it in the direction of arrow A2 includes a suction passage 1a, a discharge passage 1b, and return holes 1c and 1d (see FIGS. 2 and 5). ) Is formed inside a hollow casing 1 in which a pair of drive gear 2 and driven gear 3 are engaged with each other and
The drive shaft 6 and the driven shaft 7 which are rotating shafts are rotatably supported by bearings 4 and 5 arranged on both side surfaces of 2 and 3. The bearing
Lubricating grooves 4a, 4b, 5a, 5b on 4,5 respectively (see Fig. 3, 4)
Are formed.

In FIG. 3, the rear end of the casing 1 is a rear wall member 8
And a pair of return grooves 8a communicating with the return holes 1c are formed on the inner surface of the rear wall member 8. Then, the recirculation groove Ka is formed by the recirculation groove 8a and the recirculation hole 1c.

Also, the front end of the casing 1 has a staffin box 1 having a rotary shaft through hole 12a through which a front portion of the drive shaft 6 penetrates.
Blocked by 2. And the stuffing box 1
A reflux groove 12b is formed on the inner surface of the rotary shaft through hole 12a so that the inner surface of the rotary shaft through hole 12a communicates with the reflux hole 1d.
The recirculation hole 1d constitutes a recirculation path K2.

A large-diameter gland packing hole 12a1 is formed in the front portion of the rotary shaft through hole 12a of the stuffing box 12, and a shaft fixed to the drive shaft 6 is provided inside the gland packing hole 12a1. Gland packing that slides against the sleeve 13 to prevent liquid leakage from inside the pump
14 is installed. A seal member 15 such as an O-ring is arranged between the inner peripheral surface of the shaft sleeve 13 and the outer peripheral surface of the drive shaft 6.

The gland packing 14 is externally pressed and held by a packing retainer 17 which is detachably fixed to the stuffing box 12 by a screw 16. This packing foot 17
The outer peripheral surface 17a is formed as a seal surface that fits into the inner peripheral surface of the gland packing housing hole 12a1, and the seal surface 17a is provided with a seal member 18 such as an O-ring. An inner peripheral surface 17b of the packing retainer 17 is formed as a seal surface that fits with the outer peripheral surface of the shaft sleeve 13, and a seal member 19 such as an O-ring is arranged on the seal surface 17b. .

A screw 13a is formed on the outer periphery of the front end portion of the shaft sleeve 13, and a seal collar 20 is screwed onto the screw 13a. The rear end surface 20a of the seal collar 20 is arranged to face the front end surface 17c of the packing retainer 17, and the distance between both end surfaces 20a and 17c thereof can be adjusted by the screw 13a.

A coupling 21 is fixed to the front end of the drive shaft 6 for connecting with a shaft rotated by a drive motor (not shown). The coupling 21 and the seal collar 20 are connected by a connecting plate 22 and bolts 23, 24 and the like.

Further, since the temperature of the liquid transferred by the gear pump G needs to be maintained at an appropriate temperature, a suitable heat medium (for example, high-temperature or low-temperature low-viscosity oil) is caused to flow around the gear pump G. A plurality of heat medium jackets C and heat medium connecting pipes N1 to N6 are provided. As shown in FIG. 1, between the heat medium jackets C, C provided separately on the left and right outer sides of the case body 1, as shown in FIGS. 2 and 4, the heat medium passage formed in the case body 1 is passed. The holes 1e communicate with each other. Various methods have been conventionally adopted for the flow of the heat medium, and an appropriate method can be adopted.

Next, the operation of the above-described embodiment will be described.

The gear pump of the present invention having the above-mentioned structure is started up by using the gland packing suitable for the high-viscosity fluid transferred in the steady state. In this case, the low-viscosity transfer fluid transferred first is transferred from the suction flow path 1a to the discharge flow path 1b. The low-viscosity transfer fluid in the discharge passage 1b is supplied to the lubrication grooves 4a, 4b, 5a, 5b of the bearings 4,5 by the pressure thereof, and lubricates the bearings 4,5 with the drive shaft 6 and the driven shaft 7. Acts as a liquid. Most of the transfer fluid that has acted as the lubricating liquid in this way flows back to the suction / discharge passage 1a through the return passages K1 and K2, but a part of the transfer fluid enters the seal member storage hole 12a1 of the stuffing box 12. Inflow. Seal member storage hole 12
The low-viscosity transfer fluid that has flowed into a1 easily passes through the high-viscosity gland packing and tries to leak to the outside of the stuffing box 12. However, the leakage of the low-viscosity transfer fluid is prevented by the sealing members 18 and 19. The sealing member 15 also prevents leakage of the low-viscosity transfer fluid which tends to leak through between the outer peripheral surface of the drive shaft 6 and the inner peripheral surface of the shaft sleeve 13. Therefore, the low-viscosity transfer fluid transferred at the time of start-up is prevented from leaking to the outside of the gear pump G by the seal members 15, 18, and 19.

After that, when the gear pump G is continuously operated, the drive shaft 6 continues to rotate, but the stuffing box 12 and the packing retainer 17 do not rotate and are held stationary. Therefore, since the inner peripheral surface of the gland packing housing hole 12a1 of the stuffing box 17 and the seal surface 17a on the outer periphery of the packing retainer 17 in contact with this inner peripheral surface do not move relative to each other, the sealing function of the seal member 18 at that portion is almost degraded. do not do. However, since the outer peripheral surface of the drive shaft 6 and the sealing surface 7b on the inner periphery of the packing presser 17 in contact with the outer peripheral surface move relative to each other, the sealing function of the seal member 19 at that portion gradually deteriorates. Further, since the drive shaft 6 and the shaft sleeve 13 rotate integrally, the sealing function of the sealing member 15 is hardly deteriorated.

When the operation of the gear pump G is continued, the outer peripheral surface of the shaft sleeve 13 and the inner peripheral surface of the packing retainer 17 which are relatively moved.
The sealing function of the sealing member 19 arranged between the 17b gradually deteriorates. However, even if the sealing function of the seal member 19 is deteriorated, the gear pump G is in a steady operation, and the viscosity of the transferred fluid is high. Therefore, when the sealing function of the seal member 19 deteriorates, the high-viscosity transfer fluid flows into the gland packing storage hole 12a1, but the high-viscosity transfer fluid leaks to the outside by the gland packing 14 for the high-viscosity fluid. Be blocked.

When the gear pump G is continuously operated for a long period of time and then shut down, the viscosity of the transfer fluid is gradually reduced to finally reach a viscosity of about water, but the gear pump G is stopped at an appropriate viscosity. Then, the connecting plate 22 is removed, and a string-like flexible seal member is wound around the surface of the shaft sleeve 13 between the outer end surface 17c of the packing retainer 17 and the inner end surface 20a of the seal collar 20 facing the outer end surface 17c. hand,
The seal collar 20 is moved in the axial direction of the drive shaft by the screw 13a. Then, the wound seal member is sandwiched between the outer end surface 17c of the packing retainer 17 and the inner end surface 20a of the seal collar 20.

When the viscosity of the transfer fluid is lowered in this state, the transfer fluid having a low viscosity passes through the gland packing 14, passes through the seal member 19 having the deteriorated sealing function, and tries to leak to the outside. The low-viscosity fluid that is about to leak to the outside of the gear pump is prevented from leaking by the string-like flexible seal member wound around the surface of the drive shaft 6. Further, since the sealing members 15 and 18 have almost no deterioration in the sealing function, the low-viscosity transfer fluid does not leak from that portion.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments, and various small designs can be made without departing from the present invention described in the scope of claims for utility model registration. It is possible to make changes.

For example, the shaft sleeve 13 can be omitted. The front end surface of the case body 1 can be closed by a plate-shaped front wall member, and a ground case having a gland packing storage hole formed on the front side of the front wall member can be mounted. Furthermore, when sandwiching the seal member between the opposing end surfaces of the packing retainer 17 and the staffin box 12,
Instead of using the screw 13a, it is possible to employ various conventionally known means for holding the two objects in the approaching state by using a spring or the like instead of using the screw 13a.

C. Effect of the Invention According to the above-described invention, the seal collar, which has the inner end surface facing the outer end surface of the packing retainer and is movable and adjustable in the axial direction of the drive shaft, rotates integrally with the drive shaft. Since it is provided, the seal member can be quickly sandwiched between the outer end surface of the packing retainer and the inner end surface of the seal collar. By doing so, the low-viscosity transfer fluid, which tends to leak to the outside through the gland packing, is prevented from leaking by the seal member sandwiched between the outer end surface of the packing retainer and the inner end surface of the seal collar. be able to.

[Brief description of drawings]

FIG. 1 is an overall perspective view of an embodiment of the gear pump of the present invention,
2 is a front sectional view of the same embodiment, FIG. 3 is a sectional view taken along arrow III of FIG. 2, FIG. 4 is a sectional view taken along line IV-IV of FIG. 2, and FIG.
FIG. 6 is a sectional view taken along line VV in FIG. 6, and FIG. 6 is an explanatory view of a conventional technique. G: Gear pump, 1 ... Case body, 2 ... Drive gear, 3 ... Followed gear, 4,5 ... Bearing, 6 ... Drive shaft, 1
2 …… Staffin box, 12a1 …… Gland packing storage hole, 14 …… Gland packing, 17 …… Packing retainer, 17c …… Outer end face of packing retainer, 20 …… Seal collar, 20a …… Inner end face of seal collar ,

Claims (1)

[Scope of utility model registration request] 1. A driven shaft carrying a driven gear, a drive shaft carrying a drive gear that meshes with the driven gear, and a bearing rotatably supporting the driven shaft and the drive shaft are housed inside a case body, and A stuffing box having a gland packing storage hole through which the drive shaft penetrates and a gland packing is stored is disposed on the front side of the case body, and the gland packing is pressed against the inner end of the gland packing storage hole and the gland packing is also provided. A gear pump in which a packing retainer having a sealing surface in contact with the inner peripheral surface of the housing hole and the outer peripheral surface of the drive shaft is disposed around the drive shaft, the drive shaft having an inner end surface facing the outer end surface of the packing retainer. A gear pump in which a seal collar movable in the axial direction is arranged so as to rotate integrally with the drive shaft.