JPH0585757B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a gear pump lubrication structure, and particularly relates to a gear pump for feeding relatively high viscosity fluids that are susceptible to thermal deterioration, such as those used in the production of plastic sheets and films. It is suitable for use in polymer extruders.

(Prior Art) A gear pump is generally used in which the bearings of the drive shaft of the drive gear and the driven shaft of the driven gear are lubricated by fluid conveyed by the drive gear and the driven gear inside the pump case. .

Conventionally, in the case of such a so-called self-lubricating gear pump, a fluid passage is provided in which both the fluid that lubricates the bearing of the driving gear and the fluid that lubricates the bearing of the driven gear flow back to the low-pressure side inside the pump case. or a fluid passageway for discharging both fluids to the outside of the pump case.

For example, in the gear pump shown in FIG. 3, a drive shaft 101 of a drive gear is supported by a bearing 102, a driven shaft 103 of a driven gear is supported by a bearing 104, and the drive shaft 101 is made to protrude outside from a pump case 105 and is connected to a motor, etc. It is connected to the drive source.

Further, the drive shaft 101 is attached to the pump case 105,
Sleeve 1 having a spiral groove-shaped labyrinth on the inner periphery
06, thereby the drive shaft 101
A shaft seal is formed.

Then, the bearing part of the drive shaft 101 and the driven shaft 103
The groove 107 connecting the bearing part of the pump case 10
5.

As a result, due to the difference between the pressure inside the pump case and the atmospheric pressure, the fluid that has lubricated the bearing part of the drive shaft 101 flows from between the ends of the shaft seal between the drive shaft 101 and the pump case 105 as indicated by the arrow in the figure. As shown, the fluid that has lubricated the bearing portion of the driven shaft 103 is also discharged from between the ends of the shaft seal between the drive shaft 101 and the pump case 105 via the groove 107.

Furthermore, the gear pump shown in FIG. 4 has a drive shaft 10.
A discharge hole 108 that connects the bearing part of No. 1 to the outside, and a discharge hole 10 that connects the bearing part of the driven shaft 103 to the outside.
9 are formed in the pump case 105. As a result, the fluid that has lubricated the bearing part of the drive shaft 101 is discharged to the outside from the discharge hole 108 as shown by the arrow in the figure, and the fluid that has lubricated the bearing part of the driven shaft 103 is discharged to the outside from the discharge hole 109. be done.

(Problem to be Solved by the Invention) When a self-lubricating gear pump is used to feed relatively high-viscosity fluid, the drive shaft must protrude from the pump case to connect it to a drive source such as a motor. A shaft sealing portion must be formed by interposing a sleeve having the labyrinth between the pump case and the drive shaft to regulate the flow of fluid and prevent it from easily flowing out.

Therefore, the lubricating fluid in the bearing portion of the drive shaft inevitably stagnates in the shaft seal portion. When a relatively high viscosity fluid is sent by a gear pump, the gear pump must be heated with a heater to prevent the fluid from solidifying, and the bearing of the drive shaft must be heated due to friction between the fluids. The lubricating fluid remains at a high temperature for a long time due to stagnation.

If such a conventional gear pump is used to feed a material that is subject to significant thermal deterioration, such as polycarbonate or methacrylic resin, the material will change in quality and become colored due to thermal deterioration.

Therefore, in conventional gear pumps in which the lubricating fluid from both bearings is returned to the inside of the pump case, there is a problem in that colored and other deteriorated substances in the shaft sealing part of the drive shaft flow back to the inside of the pump case and contaminate the product. It was hot.

In addition, since one axial end of the drive shaft is connected to a drive source such as a motor, the temperature of the relatively high viscosity fluid sent by the gear pump is reduced by heat transfer to the motor, etc. The temperature is lower than that at the other end in the direction.

Therefore, in conventional gear pumps that discharge lubricating fluid from both bearings to the outside of the pump case, there is a difference in fluid viscosity due to temperature difference between one end and the other end in the axial direction, so there is also a difference in the amount of fluid discharged. arise.
As a result, the shaft end pressure becomes different between one end and the other end in the axial direction, and a thrust load acts on the driven shaft. As a result, since both ends of the drive shaft protrude outside the pump, no thrust load is generated, but the driven shaft moves in the axial direction, and the lubricating film between the side of the driven gear and the side of the bearing breaks and seizes up. There is a problem that the gear pump may be damaged due to galling or the like.

Furthermore, if the lubricating fluid from both bearings is discharged to the outside of the pump case, there is a problem in that there is a lot of fluid loss and running costs increase.

(Means for Solving the Problems) An object of the present invention is to provide a gear pump lubrication structure that can solve the problems of the prior art described above, and is characterized in that the driving shaft and the driven shaft are In a gear pump that is supported by a bearing part provided inside a case, and the bearing part is self-lubricated by the fluid itself carried by the rotation of a driving gear fixed to a drive shaft and a driven gear fixed to a driven shaft. , a discharge fluid passage consisting of a through hole provided in the wall surface of the pump case, or a gap around the shaft outer circumference of the shaft sealing portion of the drive shaft, for discharging the lubricating fluid that has lubricated the bearing portion of the drive shaft to the outside of the pump case; , for circulating the lubricating fluid that has lubricated the bearing part of the driven shaft into the inside of the pump case;
The fluid used to lubricate the bearing part of the drive shaft is equipped with a reflux groove provided on the inner surface of the pump case at a portion facing the end face of the driven shaft, and a reflux fluid passage that communicates with the reflux groove and reaches the low pressure side inside the pump case. The advantage is that the fluid that lubricates the bearing of the driven shaft is discharged to the outside without being circulated inside the pump case, and the fluid that has lubricated the bearing part of the driven shaft is allowed to flow back inside the pump case.

(Function) According to the gear pump configured according to the present invention, a part of the sucked fluid reaches the high pressure side from the low pressure side inside the pump case, and then reaches the bearing portion of the drive shaft. The fluid that has lubricated this bearing portion does not reach the low pressure side of the pump case, but is discharged to the outside of the pump case due to the difference between the high pressure side inside the pump case and the atmospheric hole. This prevents the fluid that has lubricated the bearing portion of the drive shaft from flowing back into the pump case.

Further, a part of the sucked fluid flows from the low pressure side to the high pressure side inside the pump case, and then reaches the bearing portion of the driven shaft. Due to the pressure difference inside the pump case, the liquid that has lubricated this bearing section flows back to the low pressure side via the case plate return groove at the end of the driven shaft and the return fluid passage provided in the pump case. Since the driven shaft end is inside the pump, there is no temperature difference between one end and the other end of the driven shaft in the axial direction, and there is no change in the viscosity of the fluid. Therefore, there is no difference in pressure between the ends of both shafts, and no thrust load is applied to the driven shaft.

(Example) Hereinafter, an example of the present invention will be described with reference to FIGS. 1 and 2.

A gear pump 1 shown in the figure is used for feeding a fluid such as a relatively high viscosity polymer, and includes a pump case 2, and a drive gear 3 and a driven gear 4 built into the pump case 2.

The pump case 2 has a hollow case body 5.
and a pair of case plates 6 and 7 attached to opposite sides of the case body 5.

The case body 5 has a bearing holding hole 14, a fluid suction hole 21, and a fluid discharge hole 22.
Further, the pump case 2 is covered with a heater 23.

The drive gear 3 and the driven gear 4 mesh with each other, and the drive gear 3 is attached to the drive shaft 8 and the driven gear 4 is attached to the driven shaft 9.

The drive shaft 8 is supported by bearings 10 and 11 on one side and the other side in the axial direction of the drive gear 3.

Further, the driven shaft 9 is supported by bearings 12 and 13 on one side and the other side in the axial direction of the driven gear 4.

These bearings 10, 11, 12, and 13 are fitted into holding holes 14 formed in the case body 5.

One axial end of the drive shaft 8 projects outside the pump case 2 through a through hole 15 formed in one case plate 6, and is connected to a drive source such as a motor (not shown). Further, the other axial end of the drive shaft 8 projects to the outside of the pump case 2 through a through hole 16 formed in the other case plate 7.

The drive shaft 8 and the through holes 15, 1 of the case plates 6, 7
6, a cylindrical cooling jacket 17 is interposed. The cooling jacket 17 has a passage 18 through which a cooling fluid such as water or air flows in the direction of the arrow in the figure, and the flow rate of the cooling fluid can be adjusted.

Further, a shaft seal portion is formed between the cooling jacket 17 and the drive shaft 8.

In the gear pump 1 described above, the drive gear 3 and the driven gear 4 are rotated by rotationally driving the drive shaft 8, and the fluid is sucked from the suction hole 21, and the outer periphery of the drive gear 3 and the driven gear 4 and the pump case 2. It is discharged from the discharge hole 22 through the inner periphery of the discharge hole 22 . At this time, the gear pump 1 is heated by the heater 23 to prevent high viscosity fluid such as polymer from solidifying.

A fluid passage is formed for lubricating the bearing portions of the drive shaft 8 and the driven shaft 9 with the fluid sent by the gear pump 1.

That is, radial grooves 24 are formed on the end surfaces of the bearings 10 and 11 facing the driving gear 3, and on the end surfaces of the bearings 12 and 13 facing the driven gear 4, so that the contact between the gear end surfaces and the bearing end surfaces is maintained by a fluid film. It is regulated to prevent seizure and galling.

In addition, axial grooves 25 are formed on the inner circumferential surfaces of the bearings 10, 11, 12, and 13, and contact between the outer circumferential surface of the shaft and the inner circumferential surface of the bearing is regulated by a fluid film to prevent seizure and galling. .

A fluid passage is formed for discharging lubricating fluid from the bearing portion of the drive shaft 8 to the outside of the drive shaft 8.

That is, a sleeve 19 is fitted onto the inner periphery of the cooling jacket 17, and a labyrinth 20 in the form of a spiral groove is formed on the inner periphery of the sleeve 19. The cooling jacket 17 and sleeve 19 are fitted onto the drive shaft 8 with a slight gap between them.

As a result, the fluid sucked by the gear pump 1 and reaching the high pressure side from the low pressure side inside the pump case 2 lubricates the bearing part of the drive shaft 8, as shown by the two-dot chain line in the figure. and sleeve 19
The pump is discharged to the outside of the pump case 2 through the labyrinth 20 and between the drive shaft 8 and the cooling jacket 17.

At this time, the flow of the fluid is regulated by the labyrinth 20, and the flow rate of the cooling fluid of the cooling jacket 17 is adjusted to adjust the viscosity of the discharged fluid, thereby preventing the amount of fluid discharged from becoming unnecessarily large.
This forms the shaft seal. Therefore, the lubricating fluid in the bearing part of the drive shaft 8 stagnates in the shaft sealing part of the drive shaft 8 and is easily deteriorated because it is kept at high temperature for a long time. There is no fluid passage formed inside the pump case 2, and the difference between the high pressure side inside the pump case 2 and the atmospheric pressure ensures that the fluid is discharged to the outside. As a result, the deteriorated fluid will not flow back into the pump case 2 and will not contaminate the product.

A fluid passage is formed for circulating the lubricating fluid in the bearing portion of the driven shaft 9 into the inside of the pump case 2.

That is, a through hole 27 is formed in the case body 5 in parallel with the driven shaft 9, and one end of the through hole 27 is opened to the inside of the suction hole 21, that is, to the low pressure side of the inside of the pump case 2. Further, the other end of the through hole 27 is opened so as to face the inner surfaces of the case plates 6 and 7. The through hole 27 and the bearing 12 of the driven shaft 9 are provided on the inner surfaces of the case plates 6 and 7.
A groove 28 is formed so as to connect with the inner peripheral hole 13. Note that if the diameters, depths, etc. of the through holes 27 and grooves 28 are made too large, it will take time for the fluid to flow and the fluid will stagnate, so it is better to set them to appropriate sizes.

As a result, a part of the fluid that is sucked by the gear pump 1 and reaches the high pressure side from the low pressure side inside the pump case 2, as shown by the dashed line in FIG.
After lubricating the bearing portion of the driven shaft 9, it flows back into the suction hole 21, ie, the low pressure side of the pump case 2, through the groove 28 and the through hole 27.

In this way, the lubricating fluid in the bearing part of the driven shaft 9 is not discharged to the outside of the pump case 2, so there is no difference in the shaft end pressure due to the difference in discharge amount, and no thrust load is applied to the driven shaft 9. There isn't. This prevents seizure or galling between the gear end face and the bearing end face. Further, fluid loss due to reduction in discharged fluid can also be reduced.

Note that the present invention is not limited to the above-mentioned embodiments, and for example, a fluid passage for discharging lubricating fluid from the bearing portion of the drive shaft 8 to the outside of the pump case 2 is provided in the case separately from the shaft sealing portion of the drive shaft 8. It may also be formed on the plates 6 and 7. Further, the fluid passage for circulating the lubricating fluid of the bearing portion of the driven shaft 9 from the high pressure side to the low pressure side is also formed by forming a groove on the inner circumferential surface of the holding hole 14 of the case body 5 instead of the through hole 27, for example. The groove 28 and the low pressure side may be connected to each other by a gap between the groove and the outer peripheral surfaces of the bearings 12 and 13.

(Effects of the Invention) According to the gear pump according to the present invention, the lubricating fluid in the bearing part of the drive shaft is discharged to the outside without being returned to the inside of the pump case, so that the fluid stagnates in the shaft seal part of the drive shaft. It does not contaminate the product even if it deteriorates due to heat, and is suitable for transporting fluids such as resins that easily deteriorate due to heat.

In addition, the lubricating fluid in the bearing part of the driven shaft is not discharged to the outside but is returned inside the pump case, and there is no difference in shaft end pressure, so no thrust load is applied to the driven shaft, and the gear It is possible to prevent damage to the gear pump due to seizure or galling due to contact between the end face and the bearing end face.

Furthermore, the amount of fluid discharged to the outside of the pump case is approximately halved compared to conventional systems that discharge lubricating fluid from the bearings of both the drive shaft and driven shaft, reducing fluid loss and reducing running costs. can.

[Brief explanation of the drawing]

1 and 2 relate to an embodiment of the present invention, in which FIG. 1 is a sectional view of a gear pump, FIG. 2 is an exploded perspective view for explaining the flow of lubricating fluid in the gear pump, and FIGS. 3 and 4 are FIG. 2 is a partial cross-sectional view for explaining the flow of lubricating fluid in a gear pump according to a conventional example. 1... Gear pump, 2... Pump case, 3... Drive gear, 4... Driven gear, 8... Drive shaft, 9... Driven shaft,
10, 11, 12, 13...Bearing, 27...Through hole,
28...Concave groove.

Claims (1)

[Claims] 1. The drive shaft 8 and the driven shaft 9 are supported by bearings 10, 11, 12, and 13 provided inside the pump case 2, and the drive gear 3 and the driven shaft are fixed to the drive shaft 8. The fluid conveyed by the rotation of the driven gear 4 fixed to the bearing part 10,
Gear pump 1 in which 11, 12, 13 are self-lubricated
In this case, a through hole 108 provided in the wall surface of the pump case 2 or a shaft sealing part 17 of the drive shaft 8 is used to discharge the lubricating fluid that has lubricated the bearing parts 10 and 11 of the drive shaft 8 to the outside of the pump case 2. A discharge fluid passage consisting of a clearance around the shaft outer circumference and a bearing portion 1 of the driven shaft 9
A reflux groove 28 provided on the inner surface of the pump case 2 at a portion facing the end face of the driven shaft 9 for circulating the lubricating fluid that has lubricated the parts 2 and 13 into the inside of the pump case 2.
The pump case 2 is connected to the reflux groove 28.
The fluid that has lubricated the bearing portions 10 and 11 of the drive shaft 8 is discharged to the outside without circulating inside the pump case 2, and the fluid that has lubricated the bearing portions 10 and 11 of the drive shaft 8 is discharged to the outside, and the bearing portion of the driven shaft 9 is A gear pump characterized in that lubricated fluid is circulated inside the pump case 2.