GB2280003A

GB2280003A - Quick shift two speed torque reducer for a gate valve

Info

Publication number: GB2280003A
Application number: GB9413335A
Authority: GB
Inventors: Taylor L Jones
Original assignee: FMC Corp
Current assignee: FMC Corp
Priority date: 1993-07-13
Filing date: 1994-07-01
Publication date: 1995-01-18
Also published as: GB9413335D0; BR9402691A; CA2127775A1

Abstract

A reducer assembly (2) for reducing the amount of torque required to rotate the stem (4) of a gate valve preferably utilizes a planetary gear assembly (14, 15, 20, 22, 24). The assembly also preferably has a shift rod (30) axially movable inside the valve stem (4) for selective manual shifting of the gearing between direct to reduced drive positions. The axial movement of the shift rod (30) moves a drive pin (28) in to engagement with either reducer drive shaft dogs (26) or direct drive shaft dogs (33). <IMAGE>

Description

OUICK SHIFT TWO SPEED PLANETARY TOROUE REDUCER FOR A GATE VALVE BACKGROUND AND SUMMARY OF THE INVENTION The present invention relates generally to fluid flow control valves and, more particularly, to a reducer assembly for reducing the amount of torque required to rotate a valve operating shaft, for example a gate valve stem. Gate valves are commonly used to control fluid flow during drilling, completion and production phases of well operations.

Typically, gate valves are operated by turning a hand wheel or other handle to actuate the gate to and from an open and closed position.

While gate valves are provided with means for handturning the stem during opening and closing operations, there are instances when the torque required to turn the stem is greatly increased and various torque assisting devices are required. Such instances arise when relatively high valve pressures create high friction between the valve gate and seat seals or when back seating operations are performed.

Certain torque assisting devices present additional costs and potential hazards.

In addition, in situations where high pressure is causing high friction on the gate and seat seal faces, opening speed of the gate is critical. To reduce wear on the gate and seal faces in such instances, it is desirable to open gates quickly. Certain torque assisting devices require additional set up and operation time.

It is therefore an object of the invention to provide effective and practical means for reducing the amount of torque required to turn a valve operating shaft and for reducing the amount of time required to operate the valve where high torque is needed.

Accordingly, the invention provides a valve operating shaft quick shift torque reducer-assembly comprising: a rotatable stem having a first end adapted to receive torque and a second end adapted to transmit said torque to the operating shaft; and reducer means selectively activated by shift means housed within the assembly to reduce the amount of torque required to turn said stem.

Further preferred features of the invention are in the dependent claims or will be apparent from the following description of an illustrative embodiment made with reference to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a sectional view of an embodiment of the torque reducer assembly of the present invention.

FIG. 2 is a sectional view taken along lines 2-2 of FIG.

1 showing the planetary gear system of the embodiment.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a torque reducer assembly (2) for a gate valve stem (4). The gate valve stem (4) is rotatably mounted in an upper housing (6) of the assembly (2). The upper end of the stem (4) is adapted to receive a handwheel (8) or other suitable handle means. The upper housing (6) is mounted to a lower housing (10) which contains a planetary gear assembly (12).

As shown in FIGS. 1 and 2, the planetary gear assembly (12) comprises.a spider housing (14) which is connected to a drive output shaft (16). The drive output shaft (16), not shown in Fig. 2, may be square in cross section for effective torque transmission. The output shaft (16) is connected to a stem for engaging a gate lifting nut (not shown). The planetary gears (20) are carried by the spider housing (14) and engage with a ring gear (15) fixedly mounted within the lower housing (10). The planet gears also engage a sun gear (22). Rotational torque is transmitted to the sun gear (22) through a connection (24) with a reducer drive shaft (18). Preferably, the reducer drive shaft (18) is square in cross section for effective torque transmission at the connection (24).

The reducer drive shaft (18) has dog grooves (26) at the top end adapted to receive a drive pin (28) fastened to a shift rod (30) housed within a central bore (5) within stem (4) by means of a pin carrier (32). When the shift rod (30) is shifted axially to a reduced drive position, the drive pin (28) engages dog grooves (26) on the reducer drive shaft (18) and transmits torque thereto. The shift rod (30) is activated manually by the operator.

In order to activate the direct drive position, the shift rod (30) is shifted axially so that the drive pin (28) engages dog grooves (33) of direct drive shaft (34).

Rotational torque is thereby transmitted through the direct drive shaft (34) and direct drive pins (36) to the spider housing (14) and drive output shaft (16).

When the shift rod (30) is in the position shown in FIG.

1, engaging neither the reducer drive shaft (18) dog grooves (26) nor the direct drive shaft (34) dog grooves (33), the assembly is in a neutral position. For the reduced drive mode a gear ratio of 5:1 is preferred, though any suitable gear ratio may be used.

Although the best mode contemplated for carrying out the present invention has been herein shown and described, it will be apparent that modification and variation may be made without departing from what is regarded to be the subject matter of the invention as defined in the claims.

Claims

CLAIMS:

1. A valve operating shaft quick shift torque reducer assembly comprising: a rotatable stem having a first end adapted to receive torque and a second end adapted to transmit said torque to the operating shaft; and reducer means selectively activated by shift means housed within the assembly to reduce the amount of torque required to turn said stem.

2. A valve operating shaft quick shift torque reducer assembly according to claim 1, wherein said stem has a central axial bore; and said shift means comprise a shift rod received in said central axial bore, wherein said shift rod is axially movable between a direct drive position and a reduced drive position for reducing the amount of torque required to turn said stem.

3. A valve operating shaft quick shift torque reducer assembly according to claim 1 or 2, wherein said reducer means comprise a planetary gear assembly.

4. A valve operating shaft quick shift torque reducer assembly according to claim 2, wherein said reducer means comprise: a direct drive shaft for directly transmitting torque to said drive output shaft through a spider housing when said shift means are in a direct drive position; a reducer drive shaft for transmitting torque to said drive output shaft when said shift means are in a reduced drive position through a sun gear located centrally to and in engagement with a plurality of planetary gears which are concentrically positioned in engagement with a ring gear and mounted on a spider housing which is connected to said drive output shaft.

5. A valve operating shaft quick shift torque reducer substantially as described with reference to or as shown in the Drawings.