US1690304A

US1690304A - Compressor unloader

Info

Publication number: US1690304A
Authority: US
Inventors: Fremont P Livingston
Original assignee: Westinghouse Air Brake Co
Current assignee: Westinghouse Air Brake Co
Priority date: 1927-04-08
Filing date: 1927-04-08
Publication date: 1928-11-06
Anticipated expiration: 1945-11-06

Description

F. P. LIVINGSTON COMPRESSOR UNLOADER Flled Aprll 8, 1927 Nov. 6, 1928 INVENTOR FREMONT P LIVINGSTON BY ATTORNEY Patented Nov. '6, 1928.

4 UNITED STATES PATENT OFFICE.

FREMONT r. LIVINGSTON, or DENVER, COLORADO, ASSIGNOR TO THE wiis'rmenousn AIR BRAKE COMPANY, OF 'WILMEBDING', PENNSYLVANIA, A CORPORATION or PENNSYLVANIA.

Applieation filed April 8,

pressor at starting is subject to the pressurein the system and consequently starts under v a considerable load, which causes the compressor motor to consume a correspondingly heavy current and imposes a severe strain on the apparatus, while the speed of the motor is building up to normal. s i 1 The principal object of my invention is to provide an improved unloading device for. air compressors.

In the accompanying drawing, the single figure is a diagrammatic view of a fluid compressing apparatus, showing my'improved unloadin means embodied therein.

Accor ing to the drawing, the fluid compressing apparatus may comprise an electric governor device 1, having a switch memher 3 for controlling the circuit of the compressor motor, an air compressor 4 having associated therewith an. unloading device 5 and a control valve device 6.

The control valve device 6 comprises a casing, having a chamber 7 containing a valve 8, subject to the pressure of a spring 9. The valve 8 has a fluted stem extending through a wall of the casing and is adapted to be engaged and operated by the movement of the governorswitch member 3 to the position for opening the motor circuit.

The unloading valve device 5 comprises a casing containing a diaphragm head 10, forming a chamber 11 at one side, containing a spring 12 acting on the diaphragm head and a chamber 13 at the opposite side connected through passage 14 to the compressor discharge assage 15. Chamber 13 is also connected y pipe 16 to the control valve chamber 7.

chamber 17 connected to the atmosphere I The unloading valve device also has a through a choked port 18 in a disc contained comranssoa UNLOAQDER.

1927. Serial mi; 182,092

in a screwplug having screw-threaded engagement with the casing wall and containing a poppet valve 19, adapted to seal on a seat ring 20 formed on an apertured plug 21 having "screw threaded engagement'in the casing and forminga wall between the

chambers

13 and 17. The valve 19 is carried by a stem, wh ch exten-dsthi'ough a centralopenmg in the plug 21 and is secured to the dia phragm 10.- v i In operation, when the governor switch is in the position shown in th'edrawing, the compressormotor circuitis closed and the compressor operates to compress air'into the discharge passage 15, thence past the usual discharge valve 22' andthrough pipe 23 to a storage reservoir 2.

Whenthe pressure in the'reservoir 2 has been increased to a predetermined degree, the governor device 1 1S operated to cause the switch member 3 to move up and open the the running of the compressor.

The switch member 3, upon upward movement to open the compressor circuit-,engages compressor i'moto'r circuit and "thereby stop and opens the control valve 8, which connects.

chamber 7 to the atmosphere. Chamber 7 being connected through pipe 16 to the dia phragm chamber 13 and through passage 14 to the compressor discharge passage 15, the diaphragm chamber 13 and passage 15 are also connected to the atmosphere.

Fluid under pressure in the reservoir 2 acts on the discharge valve 22 to hold it seated, so as to prevent back flow into pas sage 15 and to the atmosphere.

The venting of fluid under pressure from the diaphragm chamber 13 permits, the pressure of spring 12 to shift the diaphragm head 10 and valve 19 upwardly, so as to unseat the valve 19. V V 1 When the pressure in the-reservoir2 becomes reduced to a predetermined degree,

the governor device 1 operates to cause the switch member 3 to close the motor circuit I and start the compressor. The movement of the switch member 3 to close the motor circuit also permits the valve 8 to close.

With the compressor discharge passage 15 connected to the atmosphere through chamber 13, past the opened valve 19, through chamber 17 andthe choked port 18, fluid from the compressor flows to the atmosphere on the compression stroke, consequently, at

starting there is substantially no resistance to the operation of the compressor and it quickly attains normal speed.

The pressure of fluid in passage 15 and acting on the diaphragm 10 is gradually in creased, since the compressor supplies fluid under pressure at a greater rate than it can escape through the restricted port 18, until the pressure on the diaphragm is sufficient to overcome the pressure of the spring 12. The diaphragm 10 is then operated to close the valve 19 and the compressor then operates in the usual manner to recharge the reservoir 2.

With the above described construction, the compressor will not be started under full load. but the load is gradually applied according to the time required to obtain a suflicient pressure on the diaphragm head 10 to close the valve 19. The rate of applying the load to the crunpressor may be varied by changing the size of the choked port 18.

This unloading apparatus may be applied to an type of compressor. for either fluid or liquid, and I do not desire to restrict my invention to any particular type of fluid compressor.

Having now described my iiivention, What I claim as new and desire to secure by Letters Patent. is

1. In a pressure control apparatus, the combination with a fluid compressor, of means for venting fluid from the fluid discharge side of the con'lpresso r and operated upon a predetermined increase in the pressure of fluid discharged for cutting oil the venting of fluid from said discharge side.

2. In a pressure control apparatus, the combination with a fluid compressor, of a movable abutment subject to the pressure of fluid discharged from said compressor, and a valve operated by said abutment for opening a vent for fluid discharged from the compressor.

3. In a pressure control apparatus, the combination with a iluid compressor, o'l a movable abutment subject to the pressure of fluid dischargedv from said con'ipressor. a valve operated by said abutment for venting iluid from the discharge side of the con'ipressor. and meansoperated by a moving part of said governor for venting fluid from said movable abutment.

l. In a pressure control apparatus. the combination with a fluid compressor and a compressor governor, of a movable abutment subject to the opposing pressures of a sprim: and the pressure of fluid discharge from said conuiressor, a valve operated by said abutment for venting fluid discharged fron'i said compressor. and a valve ope 'ated by a moving part of said governor for venting 'fluid from said movable abutment.

In testimony whereof I have hereunto set my hand.

FREMONT P. LIVINGSTON.