US1602938A - Compressor-unloading mechanism - Google Patents

Description

M. RIESNER COMPRESSOR UNLOADING MECHANISM Filed Sept. 1, 1925 2 Sheets-Sheet 1 Oct. 12 1926. 1,302938 M. RIESNER COMPRESSOR UNLOADING MECHANISM Filed Sept. 1. 1925 2 Sheets-Sheet 2 19 i I 28 2 2e avw'emto'a Patented Oct. 12, 1926.

UNITED STATES 1,602,938 PATENT OFFICE.

MICHAEL RIESNER, F CINCINNATI OHIO, ASSIGNOR 'IO WORTHINGTON PUMP AND MACHINERY CORPORATION, OF NEW YORK, Y., A CORPORATION OF VIRGINIA.

COMPRESSOR-UN LOADING MECHANISM.

Application filed September This invention relates to improvements in compressor unloading mechanism.

It is the especial object of the present in-- vention to provide a combined starting and pressure unloading mechanism for compressors which shall be durable and reliable in operation, comparatively simple in construct-ion', and which may be used with advantage in compressing plants in which the compressor is belt-driven or direct-connected to a prime mover, such, for example, as an electric motor. While the improved mechanism may be applied to either duplex single stage or duplex two stage compressors, as well as, compressors of other types, and obviously may be so associated with such compressors as to secure a balanced construction, for convenience of illustration preferred and modified forms of the invention have been shown as applied to but one double-acting compressor cylinder and its receiver. In its preferred form, the invention includes pressure operated valves arranged to cooperate with each other and a speed-controlled valve for varying the de-- livery of the compressor while running at normal speed, and for automatically unloading the compressor on stopping so as to enable the driving motor on starting up to attain approximately normal or synchronous speed before the compressor takes up its load. Other features of the invention not specifically alluded to above will be hereinafter fully described.

To enable the invention to be fully under stood, preferred and modified constructions of the improved apparatus will now be described in detail in connection with the illustration thereof in the accompanying drawings, and the features forming the invention then be specifically pointed out in-the claims. In the'drawings Figure 1 is a side elevation of a compressor plant-embodying the invention in a preferred form as applied to a double-acting compressor cylinder and its receiver;

Figure 2 is a similar view of the compressor cylinder and associated apparatus on an enlarged scale and partially in section, and

Figure 3 is a side elevation, partially in section, showing a modified form of adetail feature of the apparatus.

Referring now to the drawings, and espe cially Figs. 1 and 2, 10 indicates a doubleacting compressor cylinder with the usual 1, 1925. Serial No. 53,818.

piston arranged to work therein, although it Wlll be understood that the improved ap-v paratus may be readily applied to single or double-acting cylinders and receivers thereupper end of the casing of a trigger valve 21. The latter consists of a casing having a piston valve 8 therein arranged to be depressed by fluid pressure against the tension of spring 1. Enlargements 23, 22, on such piston 8 control ports 0, 0!, respectively, such ports in turn being connected by pipes 24, 25, respectively, with casings 26, 27 mounted on the cylinder casting. The plungers 28 in the latter casings are arranged to be moved downward by fluid pressure against the tension of springs 2. At their lower ends theplungers 28 carry fingers 29 arranged, in the present case.- to coact with the valve strips of suction valves 30, 31 of the type hereinafter referred to, located, respectively, on the crank and.head ends of the cylinder shown, so as to completely or partially unload the compressor and also load the same in accordance with predetermined receiver pressures, as well as to secure complete unloading of the compressor cylinder when the compressor stops, as will be hereinafter more fully described. The enlargement 22 of the valve 8 is provided with a small passage e, the purpose of which will also appear later. To the lower end of the casing of trigger valve 21 is connected pipe 32, which at its other end is connected to the casing of a trigger valve 33 of well known type, such, for example, as disclosed in United States Letters Patent No. 1,441,840, dated Jan. 9, 1923. The valve body 3 of this'trigger valve is normally held seated by spring 4. In the present arrangement the casing of trigger valve 33 is provided with passages f, g, and a vent h, the purpose of which will a pear from the description of operation creafter. The receiver connection to the trigger valve is by way of pipes 34, 35, the latter being a continuation of pipe 19 above referred to. The suction valves 30, 31, as well as the discharge valves 36, 37, preferably and as shown, are of the strip type disclosed in United States Reissue Letters Patent No. 13,991, dated October 12, 1912, and United State Letters Patent No. 1,341,145. dated May 25, 1920, although valves of any other suitable type may be employed.

While the apparatus thus far described will function efficiently in accordance with the description of operation hereafter given to automatically unload the compressor cylinder as the compressor comes to a stop, so that in starting up the driving motor may\ attain approximately normal or synchronous speed before compressing action begins. and will also automatically reduce the delivery of the compressor when the receiver pressure. with the compressor running at maximum delivery, reaches a predetermined point, means arranged to co-operate with such combined starting and pressure unloading mechanism are preferably provided so that the driving motor may be automatically stopped and started in accordance with the demands on the receiver. \Vhile various devices of well-known construction may be employed for this purpose, there is shown in Fig. 1, more or less diagrammatically, an arrangement which includes a connection 38 between the receiver and a pressure regulator 39 of any well-known type. In the present arrangement, however, the pressure regulator 39 is set to function so as to throw the main switch 40 controlling the electric circuit to the driving motor, only when the pressure in the receiver rises slightly above the pressure required to throw the trigger valve mechanism 33. Thus, when the pressure regulator functions, the main switch 40 is opened thereby, the compressor thus shut down, the speed responsive mechanism and associated devices then functioning to completely unload the compressor. In the present arrangement, also, the pressure regulator 39 is set to function on a comparatively slight drop .in the high pressure required to actuate it as above, so as to again close the main switch 40 and start the compressor driving motor. 1

A brief description of the operation of the preferred construction will-now .be given: In Fig. 2 the respective parts are shown in the positions they occupy with the compressor running at normal speedand delivermg the maximum volume of fluid to the receiver. Assuming that with the compressor thus'running at normal speed and delivering at maximum capacity, the 're-. celver pressure rises to a point which may be readily predetermined by adjustment of the trigger valve spring 4, such pressure,

plied through pipes 35. 34 to the trigger valve body 3, will force the latter downward against the tension of spring 4 and thus shut off communication with vent h in the casing of trigger valve 33. Pressure fluid thus admitted to. the upper side of the valve body 3 will. by way of passages f, g and pipes 32, 21. pass into the casing 26 of suction valve 30. depress the plunger 28 therein. and bring the fingers 29 carried by such plunger into contact with the valve strips, thereby holding such strips off their seats and unloading the crank end of the cylinder. The delivery of the compressor is thus reduced one-half. Assuming. now, that the receiver pressure rises, it will, when slightly above that required to operate the trlgger valve as above described, be applied by way of pipe 38 (Fig. 1) to pressure regulator 39, causing the latterto throw main switch 4) and thus break the electric circuit to motor 13, and thus stop the compressor. As this oz'curs, the pilot "alve piston 16, being raised by the spring attached thereto and against the tension of which the piston 16 was depressed by the centrifugal force applied by the governor weights in operation, will place ports a, b in communication with each other, so that receiver pressure, by way of pipes 35, 19, ports a, b, above referred to, and pipe 20, will then be applied to the piston 8 of the trigger valve 21, depressing such piston against the tension of spring 1 and placing ports 0, (l in communication with each other. Receiver pressure will now be maintained in casing 26 by way of pipes 35, 19, ports a, b, pipe 20, passage e in enlargement 22 of the trigger valve 21 and pipe 24, instead of through the trigger valve 33 and the connections above referred to. At this time, also, fluid pressure admitted through the above connections and port (I and pipe 25 will be applied to the plunger 28 in casing 27, de-' pressing the same and placing the head end of the cylinder in unloaded condition in the same. wa) as described with reference to ,the crank end thereof. Both ends of the cylinder are thus unloaded as the compressor stops, and remain so until the driving motor is again started. As above stated, a

slight drop in receiver pressure below that which was necessary to actuate the pressure regulator 39 to stop the compressor driving motor, will cause such regulator to again functlon to close switch 40 andstart the driving motor 13. As the compressor comes up to normal speed the piston of the pilot valve is raised to the position shown, thus releasing the pressure above the trigger piston valve 8 and permitting the spring 1 there of to return the trigger piston valve 8 to the position shown. This permits the escape to atmosphere, by way of port I). pipe 20, passage 0 in enlargement 22 of the piston apvalve 8, and pipe 25, of pressurefluid in casconnected to mg 27. If the pressure in the receiver is suflicient, the crank end of the cylinder may remain unloaded until a further drop in receiver pressure occurs, but when the receiver pressure reaches a point below that required to operate the trigger valve 33-, the latter will be returned to its seat by spring 4, whereupon pressure fluid in pipe 32 and below enlargement 23 of the piston valve 8 will pass to atmosphere by way of passage 9 and vent h. The parts are now as shown in Fig. 2. Another rise in receiver pressure to a predetermined point will again throw the trigger valve 33 to reduce the delivery as above explained, while a slight additional .rise in receiver pressure will cause the compressor to again stop, as above described.

While the preferred construction above described will function efficiently with either a belt-driven or direct-connected motor drive for the compressor, the modified construction shown in Fig. 3 is especially applicable to installations where the compressor is direct-connected to a synchronous motor.

In the modification of Fig. 3, there is provided an upwardly opening check valve 41 in pipe 42, which latter at its lower end is port 6 in the pilot valve casing 17 (Fig. 1). At its other end such pipe is connected to the upper end of the casing of a trigger valve mechanism 43 somewhat similar to that of Fig. 2, the piston of the trigger valve being normally held in the position shown by spring 5 and provided with enlargements 44, 45 arranged to control ports m, 12. Port m is connected by pipe 46 and branches (not shown) with the casings 26, 27 of suction valves 30, 31 (Fig. 2). Port n is connected by pipe 47 to casing of a trigger valve mechanism 48 similar to that of Fig. 2. Pipe 49, leading to the receiver, is connected to the casing of trigger valve 48, which latter, in the present showing, is provided with passages 0, p and a'vent r arranged to be controlled by the trigger valve body 6, which latter is normally held seated as shown by spring 7. The tension of the spring 7 may be readily adjusted so that the trigger valve will function at a predetermined receiver pressure. In the pipe 42 there is provided a by-pass connection 50 around check valve 41,.a vent s beingprovided in such by-pass connection for a purpose which will be hereafter explained.

When the electric motor is direct-connected to the compressor, it is preferable to provide a time element between the moment when the pilot valve starts to function to load the compressor and the moment when he compressor takes up its load, so as to permit the motor to attain synchronous speed before compressing action begins. This result is secured in the modified arrangement shown by setting the pilot'valve so that it will start to function when about of the full speedof the compressor has been attained, and this adjustment of the pilot valve, in connection with the size of the vent s in by-pass connection 50, will determine the time which will elapse before the fluid above the piston casings 26, 27 of suction valves 30, 31 has escaped to atmosphere by way of pipes 46, 47, passage p and vent r in the trigger valve casing 48, the latter vent being opened when the receiver pressure falls sufliciently to permit the spring 7 to return the trigger valve body 6' to its seat. Pressure fluid above the enlargement 44 of the valve 43 has also escaped to atmosphere by way of pipe 42. by pass 50 and vent s. VVitlf the parts in these positions a brief description of the operation of the modified construction will now be given: Assuming that the compressor is running at normal speed and the receiver pressure rises to apoint which may be readily predetermined by adjustment of the trigger valve spring 7, the valve body 6 of the trigger valve is forced downward against the tension of spring 7 by fluid admitted through pipe 49 connected to the receiver, thus closing vent r by cutting off communication therewith through passage p. Fluid A thus unload both the head and crank ends,

of the cylinder quickly. Assuming now that the compressor is permitted to run continuously while thus unloaded, a drop in receiver pressure to a point below that which was necessary to actuate the trigger valve as above described will permit spring 7 thereof to return the trigger valve body 6 to its seat, thus opening communication withvent r in the trigger valve casing. This permits escape of pressure in the casings 26, 27, by way of pipe 46, ports m, n, pipe 47, and passage p to atmosphere at the vent 1'. so that the compressor is automatically loaded while running at normal speed. )Vhen the co1 n pressor is stopped, receiver pressure admitted through pipes 35.19, and ports a, b, (Fig. 1) to pipe 42 connected to the latter port. will. as in the case of Fig. 2, be applied to the unloader valve piston. depressing the same until enlargement 44 thereon exposes port m to the pressure above the piston, so that receiver pressure will be applied by pipe 46 and branches (not shown) to the casings 26, 27 to unload the compressor as above described. In starting up, the time element above referred to depends on the setting of the pilot valve so as to function when at about 90% of the full speed of the phere by way of pipe 42. The driving m0- tor is thus permitted to attain its synchronous speed before the piston of the trigger valve 43 rises sufliciently to place ports m, 'nin communication with each other and thus permit escape of fluid pressure from casings 26, 27 by way of pipe 46, ports m, n, pipe 4.7, passage 79 and vent r in trigger valve casing 48, as above described. A manually controlled switch for starting and stopping the compressor may be used with the modified arrangement of Fig. 3 or automatic stopping and starting means such as described with reference to Figs. land 2 may be employed to stop and start the motor.

, bination with a double acting. compressor at the desired pressures.

It will be understood that various changes in the construction and arrangement of the parts herein shown and described may be made, while still retaining the invention defined by the claims.

What is claimed is:

1. A combined starting and pressure unloader for compressors, comprising, in com bination with a compressor cylinder and its receiver, a valve on said cylinder, a fluid pressure operated device for operating said valve to load and unload said cylinder, a fluid pressure connection to said device, a speed-controlled valve arranged to control the latter connection, and connections between the receiver and said device including pressure operated valves arranged in series to co-operate with each other and the speedcontrolled valve to actuate said device to unload and load said cylinder at predetermined receiver pressures while the compressor is running and to unload and load said cylinder for stopping and starting.

2. A combined starting and pressure unloader for compressors, comprising, in combination with a double-acting compressor cylinder and its receiver, valves for opposite ends of said cylinder, fluid pressure actuated devicesfor operating said valves to unload and load said cylinder, fluid pressure connections to said devices, a speed controlled valve arranged to control the'latter connections,

I and connections between the' receiver and said devices including pressure operated valves arranged in series to co-operate with each other and the speed controlled valve to actuate one of said devices to unload and load one end of said cylinder at predetermined receiver pressures while the compressor is running and both of said devices to unload and load both ends of said cylinder for stopping and starting.

3. A combined starting and pressure unloader for compressors, comprising, in combination with a compressor cylinder and its receiver, a valve on said cylinder, at fluid pressure operated device for operating said valve to load and unload said cylinder, a fluid pressure connection to said device, a speed-controlled valve arranged to control the latter connection, connections between the receiver and said device including pressure operated valves arranged in series to co-operate with each other and the speed-' controlled valve to actuate said device to unload and load said cylinder at predetermined receiver pressure while the compressor is running and to unload and load said cylinder for stopping and starting, and means controlled by predetermined receiver pressures for starting and stopping the compressor.

4. A combined starting and pressure unloader for compressors, comprising, in comcylinder and its receiver, valves for opposite ends of said cylinder, fluid pressure operated devices for operating said valves to unload and load said cylinder, fluid pressure connections to said devices, a speed controlled valve arranged to control the latter operated valve being arranged to be opened at a predetermined receiver pressure and to cooperate with the first named pressure operated valve and the speed controlled valve to unload and load one end of the compressor cylinder while the compressor is running at normal speed.

5. A combined starting and pressure unloader for compressors, comprising, in combination with a double-acting compressor cylinder and its receiver, valves for opposite ends of said cylinder, fluid pressure operated devices for operating said valves to unload and load said cylinder, fluid pressure connections to said devices, a speed controlled valve arranged to control the latter connections, a pressure operated valve in said connection arranged to co-operate with the speed-controlled valve to automatically unload both ends of said cylinder under control of the compressor speed, an independent connection between said pressure actuated a compressor, and ineans controlling said devices and the receiver including a pressure operated valve normally closing the latter connection, said last named pressure operated valve being arranged to be opened at a predetermined receiver pressure and tomoperate with the first named pressure operated valve and the speed controlled valve to unload and load one end of the compressor cylinder while the compressor is running at normal speed, and means controlled by predetermined receiver pressures for starting and stopping the compressor.

6. A combined starting and pressure unloader for compressors, compris1ng,-in combination with a compressor cylinder and its receiver, a valve on said cylinder, a fluid pressure operated device arranged for operacting said valve to unload and load said cylinder, a fluid pressure connection to said device, a speed controlled valve arranged to control the latter connection, and connections between the receiver and said device including pressure operated valves arranged in series to cooperate with each other and the speed controlled valve to actuate said device to unloadand load the cylinder at predetermined receiver pressures while the compressor is running and to unload and load said cylinder for stopping and starting, an electric motor arranged to drive said valve and pressure operated valve for the free transmission of pressure fluid to and from said pressure operated valve for actuating the valve to load and unload the compressor, said connections and the pressure operated and speed controlled valves being arranged to co-operate with each other to delay loading relatively to the movement of the speed controlled valve.

8. In a compressor unloader, the combination, with the trigger valve 21, and a speed controlled valve and connections for controlling said valve" by the compressor speed, of triggervalve 33 and connections for controlling said valve by receiver pressure, and connections between said trigger valves whereby the pressure fluid transmitted through trigger valve 33 is controlled by trigger valve 21, substantially as described.

In testimony whereof, I have hereunto set my hand.

MICHAEL RIE'SNER.

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