JPS6338692A - Seal device for plunger pump - Google Patents

Abstract

PURPOSE:To eliminate the need for an elastic packing, by defining a labyrinth seal groove having a C-shaped cross-section in a ring state on the inner circumference of a cylindrical cylinder and the outer circumference of a piston. CONSTITUTION:A labyrinth seal grooves 20 having a C-shaped cross-section is defined in a ring state at a portion near to a lower portion of the inner surface 15a of a cylindrical cylinder 15. When a piston 14 moves upwardly, fluid in the cylinder is compressed and discharged and at the same time the pressure of the fluid causes the fluid to enter into the labyrinth seal groove 20 through a very narrow gap S. When the fluid flows against a direction in which the piston operates (in a direction shown by an arrow of a solid line), its pressure is greatly reduced by its viscosity and the pressure is further reduced when the fluid disperses and expands in the groove 20 so that the fluid is prevented from leaking. When the piston 14 is in a suction stroke (in a direction shown by a dotted line), the pressure in the cylinder 15 is made negative to sucking the fluid into the cylinder 15 so that leakage is securely prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a sealing device between the inner peripheral surface of a cylinder and the outer peripheral surface of a piston in a reciprocating sliding plunger pump.

(Prior art) Generally, the sealing device in this type of plunger pump has an elastic packing and a packing inserted between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston, and the U packing and the packing are connected to the piston. The piston has a structure that seals between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston by bringing the piston into contact with the outer circumferential surface of the piston.

(Problems to be Solved by the Invention) In the conventional sealing device configured as described above, a relatively expensive U-packet and V It becomes expensive because it requires packing. ' Moreover, since the outer circumferential surface of the piston is constantly rubbing against the U and V seals, the U and V seals wear quickly and have low durability. Therefore, [J-7 and V-packs must be replaced frequently each time they wear out, and the replacement work requires time and effort.In addition, the plunger pump is stopped during replacement work, so the plunger pump The operating efficiency of the pump will decrease.

Furthermore, powder from the U-pack, kin, and ■-pack that are worn out during the operation of the plunger pump, and fragments of the U-pack and ■-pack that are damaged and peeled off, can get mixed into the fluid inside the cylinder, making it difficult to use for food filling. The pump had some undesirable problems.

The present invention has been proposed in view of the above-mentioned problems, and makes it possible to omit the U-packet and ■-packet that are conventionally provided between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston, while maintaining high sealing performance. The purpose is to

(Means for Solving the Problems) In order to achieve the above object, a plunger pump sealing device according to the present invention includes a cylindrical cylinder and a piston that slides inside the cylinder and pumps fluid inside the cylinder. In the plunger pump, at least one labyrinth seal groove is formed in an annular shape on either the inner circumferential surface of the cylinder or the outer circumferential surface of the piston.

(Function) When the piston operates and pressurizes the fluid in the cylinder and discharges it, the pressurized fluid flows through the extremely narrow gap between the inner peripheral surface of the cylinder and the outer peripheral surface of the piston, causing the piston to operate. It flows in the opposite direction to the labyrinth seal groove.

Here, when the fluid flows through the extremely narrow gap between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston against the direction of piston operation, the pressure of the fluid flowing into the labyrinth seal groove is significantly attenuated due to the viscosity of the fluid. Ru.

Then, when the fluid whose pressure has been significantly attenuated diffuses and expands in the labyrinth seal groove, the pressure is further attenuated, so that leakage of the fluid from the labyrinth seal groove toward the tappet portion side is reliably prevented.

(Example) Hereinafter, a sealing device for a plunger pump according to the present invention will be described based on the drawings.

FIG. 1 shows the general structure of a three-cylindrical plunger pump. This plunger pump 1 consists of a pump casing 2 and a confluence part 3 attached to the upper part of the pump casing 2. is crank case 4
, a tappet part 5, and a pump part 6 are formed in this order from the bottom.

A crankshaft (not shown) is rotatably supported on the crankcase 4 over its left and right side walls, and two large-diameter gears 7, 7 fixed to the crankshaft are mounted on the M outer side. For example, the small diameter gear 9 for driving the drive shaft 8 is driven by a drive device composed of an electric motor, a drive pulley, a passive pulley, etc.
It is designed to be rotationally driven through.

In the tappet section 5, a cylindrical tappet 1) of Miki is supported on a partition wall 10 so as to be slidable in the vertical direction, and the lower part of the tappet 1) is a disc-shaped crank arm 12 provided on the crankshaft. When the crankshaft is rotated, the tappet 1) is vertically driven up and down via the crank arm 12 and the connecting rod 13.

The pump section 5 consists of a cylindrical plunger 14 whose lower end is fixed to the upper end of the tappet 1), and a cylindrical cylinder 15 that fits onto the plunger 14. The upper end is pressed against the fluid pressure inlet 18 of the merging section 3 by a compression spring 17 installed between the lower end and the partition wall 16 that slides and guides the plunger 14.

Further, a cylindrical cylinder 15 into which the plunger 14 is fitted
A labyrinth seal groove 20 is provided at the lower part of the inner circumferential surface 15a of the
is formed.

As shown in FIGS. 2 and 3, the labyrinth seal groove 20 is composed of five annular grooves each having a U-shaped cross section on the inner circumferential surface 15a of the cylinder 15.

The confluence part 3 attached to the upper part of the pump casing 2 has a linear main passage 21 and a branch passage 2 branched from the main passage 21.
2, a discharge valve 24 biased to close by a compression spring 23 is provided in the main passage 21 side portion of this branch passage 22, and the fluid pressure inlet 18 is provided at the end portion on the pump portion 6 side.
is formed.

Note that reference numeral 25 in FIG. 1 is a fluid inlet formed in the pump portion 6 of the pump casing 2.

Next, the operation of the sealing device of the plunger pump 1 configured as described above will be explained.

When the drive shaft 8 is driven by a drive device (not shown) and the crankshaft is rotationally driven via the small diameter gear 9 and the large diameter gears 7, 7, the crank motion of the crankshaft causes the connecting rod 13 to rotate the tappet 1). It is driven up and down.

When the piston 14 is raised by the vertical movement of the head 1), the fluid in the cylinder 15 is pressurized and is discharged from the branch passage 22 into the main passage 21 by pushing open the discharge valve 24 against the compression spring 23. .

At this time, the fluid in the pressurized cylinder 15 passes through the labyrinth seal from an extremely narrow gap between the inner circumferential surface 15a of the cylinder 15 and the outer circumferential surface 14.3 of the piston 14, as shown in FIG. The fluid flowing into the labyrinth seal groove 20 flows into the inner peripheral surface 15 of the cylinder 15.
When the fluid flows through the extremely narrow gap S between the outer circumferential surface 14a of the screw 14 and the outer circumferential surface 14a of the screw 14 against the operating direction of the piston 14 (in the direction of the solid line arrow in FIG. 4), the viscosity of the fluid causes The pressure of the fluid flowing into the is significantly attenuated.

The pressure of the fluid whose pressure has been greatly attenuated is further attenuated when it diffuses and expands in the labyrinth seal groove 20, so that leakage of the fluid from the labyrinth seal groove 20 to the tappet portion 5 side is prevented.

Next, when the piston 14 finishes rising and begins the suction process (in the direction of the dotted arrow) in which it descends from the top dead center, the inside of the cylinder 15 becomes negative pressure, and the inner circumferential surface 15a of the cylinder 15 and the outer circumferential surface 14a of the piston 14 The fluid that had flowed into the labyrinth seal groove 20 from the gap S between the two is sucked back into the cylinder 15.

As a result, the tappet portion 5 is removed from the labyrinth seal groove 20.
This reliably prevents fluid from leaking to the sides.

5 shows a modification of the labyrinth seal groove 20, which is a modification of the labyrinth seal groove 20.
A seal piece 25 having a curved cross section is attached to the groove end of the labyrinth seal groove 20 on the side facing the inflow direction of the fluid flowing into the labyrinth seal groove 20 from the extremely narrow gap S between the outer peripheral surface 14a of the piston 14 and the outer peripheral surface 14a of the piston 14. It is formed so that it is formed.

In such a case, the pressure of the fluid flowing into the labyrinth seal groove 20 causes the seal piece 25 to close on the outer peripheral surface 14a of the piston 14.
Since it is pressed to the side, sealing performance is improved.

Further, in each of the above embodiments, a plurality of labyrinth seal grooves 20 are provided, but depending on the pressure of the fluid and the volume of the labyrinth seal grooves 20, it is also possible to use wood.

Further, although not shown, the labyrinth seal grooves 20 on each implementation side may of course be provided on the outer circumferential surface of the piston instead of on the inner circumferential surface of the cylinder.

(Effects of the Invention) As described above, according to the plunger pump sealing device according to the present invention, the U-packet and the Since the packing can be omitted, the manufacturing cost can be reduced accordingly.

Furthermore, since there are no U-packs, 7-pieces, and V-packs that wear out relatively quickly, there is no need to replace the U-packs and ■-packs, and the plunger pump can be operated accordingly, resulting in higher operating efficiency. can be significantly improved.

In addition, the fluid discharged from the cylinder by the piston has [J
(I
It has the advantage that it is suitable for plunger pumps used for filling foods, since it does not contain any loose debris or debris.

[Brief explanation of the drawing]

The drawings show an embodiment of the present invention; FIG. 1 is a partially cutaway perspective view of a vertical three-cylinder plunger pump, FIG. 2 is a partially cutaway exploded perspective view of the main parts, and FIG. 4 is an enlarged view of the main part for explaining the action, and FIG. 5 is an enlarged view of the main part on the deformation side of the labyrinth seal groove. 14... Piston, 15... Cylinder, 20... Labyrinth seal groove.

Claims (3)

[Claims] (1) In a plunger pump consisting of a cylindrical cylinder and a piston that slides inside the cylinder and pumps the fluid inside the cylinder, either the inner circumferential surface of the cylinder or the outer circumferential surface of the piston A sealing device for a plunger pump, characterized in that at least one labyrinth seal groove is formed in an annular shape. (2) The sealing device for a plunger pump according to claim 1, wherein the labyrinth seal groove is constituted by a groove having a U-shaped cross section. (3) The labyrinth seal groove is defined in claim 1, wherein a seal piece having a wedge-shaped cross section is formed in an annular shape at the groove end of the labyrinth seal groove on the side facing the inflow direction of the fluid flowing into the labyrinth seal groove. Plunger pump sealing device.