US3625628A

US3625628A - Capacity control operating mechanism for centrifugal compressor

Info

Publication number: US3625628A
Application number: US60482A
Authority: US
Inventors: Edson H Byrns
Original assignee: Carrier Corp
Current assignee: Carrier Corp
Priority date: 1970-08-03
Filing date: 1970-08-03
Publication date: 1971-12-07
Anticipated expiration: 1988-12-07
Also published as: CH523430A; DE2134205C3; FR2103900A5; DE2134205B2; DE2134205A1; GB1356855A

Abstract

The capacity control means of a centrifugal gas compressor is connected to a reversible motor by motion transmitting means including a crank structure which functions to move the control member slowly as it approaches and leaves closed position. During that portion of the movement of the control member, the torque applied thereto by the motor is multiplied, permitting the use of a small motor.

Description

United States Patent Inventor Edson H. Byrns Fayettevllle, N.Y.

Appl, No. 60,482

Filed Aug. 3, 1970 Patented Dec. 7, 1971 Assignee Carrier Corporation Syracuse, N.Y.

CAPACITY CONTROL OPERATING MECHANISM FOR CENTRIFUGAL COMPRESSOR 4 Clnlms, 2 Drawlng Figs.

int. Cl F04d 27/00 Field of Search 415/ 147,

References Cited UNITED STATES PATENTS 2/1958 Christensen 6/1960 Howell 10/1961 C0lley....

1/1968 Endress.. 4/ l 968 Geyer FOREIGN PATENTS 6/1943 Germany Primary ExaminerHenry F. Raduazo Attorneys-Harry G. Martin, Jr. and J. Raymond Curtin ABSTRACT: The capacity control means of a centrifugal gas compressor is connected to a reversible motor by motion transmitting means including a crank structure which functions to move the control member slowly as it approaches and leaves closed position. During that portion of the movement of the control member, the torque applied thereto by the motor is multiplied, permitting the use ofa small motor.

PATENTEDUEE mu 3.625628 SHEET 1 [IF 2 IN VENTOR. EDSON H. BYRNS ATTORNEY PATENTEDUEU 'HHTI SHEET 2 OF 2 IIIIIIIIIILIIIIII Il/Ilfllllll FIG. 2

INVENTOR. EDSON H. BYRNS ATTORNEY CAPACITY CONTROL OPERATING MECHANISM FOR CENTRIFUGAL COMPRESSOR BACKGROUND OF THE INVENTION Many actuating mechanisms have been devised and used for operating capacity control means of centrifugal compressors. Such control means includes guide vanes and dampers arranged in the inlet of the compressor and diffuser valve structures arranged in the discharge diffuser of the compressor. In regard to the diffuser valve control mechanism, the movement thereof between open and closed positions may be at a uniform rate; and the torque required for such movement is substantially uniform.

However, in regard to inlet capacity control vanes and butterfly valves or dampers mounted in the compressor inlet, such devices are very sensitive to the gas flow when they are moved in the area near closed position; and it is, therefore, desirable to move the control member very slowly in this area, particularly in moving it from closed position. Also, movement of the control member in proximity to the closed position requires the application of substantially more torque than in actuating the member throughout the remainder of its movement.

This invention has as an object a capacity control actuating mechanism embodying an arrangement where the member is operated by a relatively small reversible motor connected to the member by motion transmitting mechanism which functions to effect slow movement of the control member by the constant speed motor when the member is traveling in proximity to the closed position; and, during movement in that area, the torque output of the motor is multiplied, permitting the economical use of a small motor.

SUMMARY OF THE INVENTION The capacity control operating motor and the control member are provided with radially extending arms connected together to impart oscillation to the shaft to which the control member is fixed. The motor output shaft is so located relative to the operating shaft of the control member, and the motion transmitting arms connected to the motor and the control member are so arranged that as the control member approaches and leaves closed position, the movement of the member is reduced in speed and a greater torque leverage applied to the operating shaft of the control member.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a vertical sectional view of the intake end of a centrifugal gas compressor of conventional form, the view including the control means operating mechanism embodying our invention; and

FIG. 2 is a view of the operating mechanism taken on line 2-2 of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. I, designates the intake section of the centrifugal compressor, the section 10 being attached to a section 11 as by means of cap screws 12. The section 11 encircles the impeller 13 fixed to the shaft 14 journaled in the main frame 15 of the compressor and to which the section 11 is attached as by cap screws 17.

The capacity control means is illustrated as a butterfly valve or damper 23 formed with a trunnion 25 journaled in one side of an annular member 26 mounted intermediate the section 10 and a section 27 as by screws 28. An actuating shaft 29 extends from the opposite side of the valve and is journaled in like manner in the frame member 26, and has an outwardly extending portion 30 to which is affixed a driven arm 31 as by means of the key 33. The arm 31 extends outwardly from the shaft 30' (see FIG. 2) and has a sliding connection with a block 35 formed with a trunnion 36 journaled in a drive arm 37.

The control operating mechanism is mounted in a sheet metal enclosure 38, the bottom wall 39 of which is attached to the section 26 as by screws 40. The frame work also includes a bracket member 43 to which a gear casing 45 is attached as by screws 47. A motor is attached to the gear box 45 to power the output shaft 51.

The drive arm 37 is fixed to the shaft 51 as by a set screw 53, the arm 37 being apertured to rotatably receive the trunnion 36 of the block 35.

The motor output or power shaft 51, and the valve shaft 30 are so located relatively, and the

arms

31, 37 are so fixed to the shafts, that upon movement of the drive arm 37 in a clockwise direction (FIG. 2) for the transmission of similar movement to the driven arm 31 and shaft 30, the speed of such movement of arm 31, and accordingly, damper 23 is reduced as the mechanism approaches the closed damper position as will be apparent from a consideration of FIG. 2 of the drawings. The motor output shaft 51 is journaled in parallel spaced relation to the shaft 30 (see FIG. 1). When the capacity control member 23 is moved to the closed position, the

arms

31, 37 are moved to the position shown in dotted outline at the left in FIG. 2, this position being indicated by the legend "closed position. When the control member has been moved to the open position, the

arms

31, 37 are positioned as shown in dotted outline at the right of FIG. 2, designated by the legend open position.

As the control member 23 is moved between open and closed positions, the driven arm 31 is moved through an arc indicated by the dotted line 54. The motor output shaft 51 is positioned a distance from the plane indicated by the line 55 extending through the axis of shaft 30 and bisecting the are 54. As illustrated in FIG. 2, the shaft 51 is spaced from the plane 55 in a direction toward the open position, and located in the sector in which the arm 31 moves.

With this arrangement, as the driver arm 37 is moved in a clockwise direction (FIG. 2), the block 35 is moved along the arm 31 toward the shaft 30. During this movement, the arm 31 is also moved in a clockwise direction, eflecting movement of the valve 23 toward closed position. Upon reversal of motor 50, the

arms

31, 37 are moved in a counterclockwise direction. Movement of these parts is limited in both directions by the outer end of the arm 37 engaging the actuating members of

limit switches

60, 61. The switch is positioned to be engaged by the arm 37 when the valve 23 is moved to closed position. The switch 61 is actuated when the valve is moved to open position.

As previously stated, the arm 31 is movable through an are indicated at 54. Due to the location of the motor drive shaft 51 and the valve driven shaft 30 as described, the valve shaft 30 is rotated slower as the valve 23 moves in the area of the closed position. The motor 50 is operated at a constant speed in both directions. Therefore, the valve 23 is moved slowly in the vicinity of the closed position. This is particularly advantageous when the compressor control means is in the form of a butterfly valve or damper, as the valve is very sensitive to flow when it is moved in the vicinity of the closed position. With the arrangement described, the first l0 of the valve movement, from closed position toward open position, the shaft 51 rotates 43 the ratio being better than 4 to I.

Also, the greatest torque required to rotate the valve is when it is at, or near, the closed position. The compressor capacity control operating mechanism embodying my invention permits the motor to deliver greater torque to the valve as it is moved toward closed position. It will be apparent that my capacity control operating mechanism is equally useful in operating conventional inlet guide vanes and annular diffuser valves. The capacity control operating mechanism of my invention obviates the need of expensive percentage timers or the like. It will be understood the motor 50 is controlled by means sensing the demand load on the compressor.

1 claim:

1. Mechanism for operating capacity control means for a centrifugal compressor, said control means being movable between open and closed positions, comprising a frame, an actuating shaft journaled in said frame and being operatively connected to said control means, a power shaft journaled in said frame in spaced relation to said actuating shaft, motion transmitting linkage connecting said power shaft to said actuating shaft, a reversible constant speed motor connected to said power shaft and operable when energized to effect oscillation of said power shaft, said motion transmitting linkage including means operable to reduce the speed of motion of said control means during movement thereof in the vicinity of the closed position.

2. Mechanism for operating capacity control means for a centrifugal compressor, said control means being movable between open and closed positions, comprising a frame, an actuating shaft joumaled in said frame and being operatively connected to said control means, a power shaft journaled in said frame in spaced parallel relation to said actuating shaft, a drive arm fixed to said power shaft and extending therefrom for movement in a plane normal to the axis of said shaft upon oscillation thereof, a driven arm fixed to said actuating shaft and extending therefrom for oscillating movement in a plane normal to the axis of said actuating shaft, said driven arm being operatively connected to said drive arm and being movable upon oscillation thereof through an are between open and closed stop positions corresponding to the open and closed positions of said control means, the axis of said power shaft being located within the sector of movement of said driven arm and spaced in the direction toward said open stop position a distance from the plane extending through the axis of said actuating shaft and bisecting said are, and a reversible motor connected to said power shaft and operable to effect oscillation thereof.

3. Mechanism for operating capacity control means for a centrifugal compressor as set forth in claim 1 wherein said driven arm is mounted for oscillation in a plane spaced outwardly from said drive am in a direction axially of said power shaft.

4. Mechanism for operating capacity control means for a centrifugal compressor as set forth in claim 1 wherein the connection between said drive arm and said driven arm includes a block pivotally mounted on said drive arm and being formed with a through aperture, said driven arm extending through said aperture and having sliding connection with said block.

Claims

2. Mechanism for operating capacity control means for a centrifugal compressor, said control means being movable between open and closed positions, comprising a frame, an actuating shaft journaled in said frame and being operatively connected to said control means, a power shaft journaled in said frame in spaced parallel relation to said actuating shaft, a drive arm fixed to said power shaft and extending therefrom for movement in a plane normal to the axis of said shaft upon oscillation thereof, a driven arm fixed to said actuating shaft and extending therefrom for oscillating movement in a plane normal to the axis of said actuating shaft, said driven arm being operatively connected to said drive arm and being movable upon oscillation thereof through an arc between open and closed stop positions corresponding to the open and closed positions of said control means, the axis of said power shaft being located within the sector of movement of said driven arm and spaced in the direction toward said open stop position a distance from the plane extending through the axis of said actuating shaft and bisecting said arc, and a reversible motor connected to said power shaft and operable to effect oscillation thereof.

3. Mechanism for operating capacity control means for a centrifugal compressor as set forth in claim 1 wherein said driven arm is mounted for oscillation in a plane spaced outwardly from said drive arm in a direction axially of said power shaft.