JPH0115748Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a lower mechanical seal of a turbo drill (downhole motor) mainly used for underground excavation.

BACKGROUND ART As shown in FIG. 4, a turbine 2 is provided at one end of a cylindrical main body 1, and a bit 5 is attached to a rotor 4 at the tip of a shaft 3 connected to the turbine 2.
The turbine 2 is rotated by muddy water sent from a mud pump (not shown), which rotates the shaft 3, rotor 4, and bit 5, and the bit 5 drills a hole 6 (well) in the rock.
The muddy water that has been rotated passes through the hole 7 of the shaft 3 and is ejected from the bit 5, and the turbo drill turns the excavated chips into muddy water and pumps it to the ground through the hole 6 and the annular space (annulus) 8 of the main body 1. Are known.

In such a turbo drill, a large load is applied to the shaft 3, so the shaft 3 and main body 1
A radial bearing 9 that supports the shaft 3 and a thrust bearing 10 that supports the thrust force due to the fluid pressure difference are provided between the radial bearing 9 and the thrust bearing 10.
An upper mechanical seal 11 and a lower mechanical seal 12 are provided between the shaft 3 and the main body 1 to shield lubricating oil and external fluid (the aforementioned muddy water).

The lower mechanical seal 12 is constantly subjected to the pressure of muddy water that transforms chips into muddy water and pumps it to the ground, and the pressure of the muddy water is high in order to effectively remove chips.
1 must be able to withstand high pressure.

In addition, turbo drills are often difficult to use for bending and digging, and when used in this way, the shaft 3
deforms and causes conical eccentric movement,
It is necessary for the lower mechanical seal 12 to prevent the sealing liquid from leaking from the sealing surface because the sealing surface follows the conical eccentric movement.

FIG. 5 is a sectional view of a conventional lower mechanical seal, in which a seal ring 14 facing the floating seat 13 on the main body 1 side is provided on a drive collar 15 having an L-shaped cross section, and the drive collar 15 is connected via a drive pin 16. It is connected to a retainer 17 fixed to the shaft 3, and the drive collar 15 is pressed by a spring 18 to press the seal ring 14 to the floating seat 13.

The torque generated at the seal surface 19 varies depending on the pressure, temperature, type of oil, sliding material, etc., but can reach 20 to 30 kg/m, so the gap between the drive collar 15 and the retainer 17 is It is made as short as possible, and the contact portion between the retainer 17 and the drive pin 16 is made long in order to reduce the contact surface pressure of the drive pin 16, so that the above-mentioned high torque can be transmitted.

Problems to be Solved by the Invention When the shaft center 3' rotates with a conical eccentric movement as shown in Fig. 6, that is, the shaft center 3' is tilted by θ degrees with respect to the main body center 1', the shaft 3 moves as shown in Fig. 7.
Due to the inclination of the drive pin 16, the retainer 1
7 and the drive collar 15 also becomes oblique, the space between the seal ring 14 and the floating seat 13 (that is, the sealing surface) opens and the sealing fluid leaks.

In other words, the floating seat 13 is fixed to the main body 1 side, and the seal ring 14 side rotates together with the shaft 3, so when the shaft 3 bends around the radial bearing, the seal ring 14
could not follow the angle of deflection, and the seal surface 19
opens in a wedge shape.

Means and action for solving the problem: The drive pin and retainer are rotated as one unit in the rotational direction, the axial bonding length is shortened, and a notch is provided in the radial direction, allowing relative displacement in this direction. The gap between the inner diameter side of the drive collar and the shaft side is increased so that when a conical eccentric movement is applied, the shaft and retainer are tilted relative to the drive pin and drive collar, and the seal ring returns to its initial position. What I tried to maintain.

Example Figure 1 is a sectional view of the lower mechanical seal, Figure 2 is a sectional view of the lower mechanical seal.
The figure is a right side view, and the retainer 17 has a plurality of radial grooves 21 formed at equal intervals in the circumferential direction of a disc 20, and an opening is formed on the outer circumferential surface of the disc 20 facing the radial grooves 21. A notched groove 22 in the radial direction is formed, and the base of the drive pin 16 is loosely fitted into this notched groove 22, and the tip is inserted into the drive collar 15.
are screwed together.

The drive collar 15 has a substantially L-shaped cross section due to the cylindrical body 24 and the flange 25, and the tip of the drive pin 16 is screwed into the screw hole 26 of the flange 25 to form a contact point between the drive pin 16 and the retainer 17. In addition to being set at a position close to the drive collar 15, an annular projection 27 is integrally formed on one side of the inner peripheral side of the cylinder body 24, and this annular projection 27 comes into contact with a sleeve 28 fitted to the shaft 3, and the sleeve 28 and the inner circumferential surface _24a , and the gap between the drive collar inner diameter side and the sleeve 28 is widened, and the drive collar 15 and the sleeve 2
8, that is, it facilitates relative displacement with the shaft 3.

29 is an O-ring.

Therefore, although the retainer 17 and the drive pin 16 rotate as one unit in the rotational direction, they can be relatively displaced in the radial direction, and the drive collar 15 is easily tilted and displaced relative to the retainer 28. Therefore, when a conical eccentric movement is applied as shown in FIG. 3, the shaft 3 and the retainer 28 are tilted and displaced together with the retainer 17 with respect to the drive pin 16 and the drive collar 15, and the seal ring 14 maintains its initial posture. The sealing surface 19 never opens.

Effect of the invention When a conical eccentric movement is applied, the shaft 3 and the retainer 17 are integrated and the drive pin 16
Since the seal ring 14 is tilted and displaced relative to the drive collar 15, the seal ring 14 maintains its initial position and the seal surface 19 does not open, thereby preventing leakage of sealing fluid.

[Brief explanation of the drawing]

1 and 2 are a sectional view and a right side view of a lower mechanical seal showing an embodiment of the present invention, FIG. 3 is an explanatory diagram of operation, and FIG. 4 is a schematic explanatory diagram of a turbo drill.
Figure 5 is a cross-sectional view of a conventional lower mechanical seal.
FIG. 6 is an explanatory diagram of conical eccentric movement, and FIG. 7 is an explanatory diagram of a malfunction. 1 is the main body, 3 is the shaft, 13 is the floating seat, 14 is the seal ring, 15 is the drive collar, 16 is the drive pin, and 17 is the retainer.

Claims (1)

[Scope of utility model registration request] A floating seat 13 on the main body 1 side and a seal ring 14 on the shaft 3 side are in sliding contact to form a seal surface 19, a drive pin 16 fixed to a drive collar 15 supporting the seal ring 14, and a retainer 17 fixed on the shaft 3 side. The drive collar 15 and
A lower mechanical seal for a turbo drill characterized by a larger gap _S1 between the inner diameter side of the shaft 3 and the shaft 3 side.