US2223712A - Relay - Google Patents

Description

H. ZIEBOLZ Dec. 3, 1940.

RELAY Filed April 12. 1937 a 1 i i 1 I IIIIIIIII I I I 1.0 PRESSURE (IN/T6 8 MAG/T/ r005 OF PRIMARY MPULSE- In veptar:

Patented Dec. 3, 1940 UNITED STATES RELAY Herbert Ziebolz, Chicago, Ill., assignor to Aslrania Regulator Company, Chicago, 111., a corporation oi Illinois Application April 12, 1937, Serial No. 136,515

9 Claims. (Cl. 137-153) This invention relates to relays, more particularly to relays of the pressure fluid type.

Relays are used to convert primary impulses,

such as forces, or positions, into secondary impulses of difierent magnitude to be used. for various purposes, such as operating measuring instruments, control apparatus, or the like.

To insure a constant and correct relation between the primary controlling impulses and the 0 secondary impulses created by the relay the latter may also be applied to act on the relay in addition, or opposition, to the controlling impulses, e. g., in such a way as to partly or entirely coun terbalance the primary impulses.

As far as I am aware, it has heretofore been the practice to derive such additional influences from a positive pressure set up in a section of a conduit adjoining a constriction through which a pressure fluid flows controlled by the said relay. The pressure set up in the said section constitutes also the secondary impulse, used further for measuring and controlling purposes.

It is an object of this invention to provide an improved relay of simple construction having a high sensitivity responding to and creating impulses of a wider difference in magnitude than heretofore.

Inasmuch as a pressure, or impulse, derived in the conventional way has a definite and positive value which is greater than zero, as will be hereinafter explained in detail, the range of the relay is limited to primary impulses having a definite and positive minimum value. Primary impulses of a lesser magnitudewill not operate the relay.

According to this invention, the disadvantages of the conventional type of relay are overcome by deriving the secondary impulse-pressure at a point of the conduit within the suction range of a constriction, whereby even negative, 1. e., suction pressure values will be attained.

Objects and advantages of this invention will appear from a consideration of the description which follows with the accompanying drawing showing embodiments of the invention for illustrative purposes. It is to be understood that this description is not to be taken in a limiting sense,

the scope of the invention being defined in the appended claims.

Referring to the drawing: Fig. 1 is a diagrammatic illustration, partly in section, of a relay mechanism Fig. 2 is a diagrammatic illustration of the v pressure conditions existing at a constriction;

trating the pressure conditions in the neighbor- Figs, 3 and 4 are diagrams-toillustrate the operation of the invention; and

Fig. 5 is a modified form of relay of Fig. 1 shown partly in section.

Pressure fluid from a source (not shown) 'is 5 flowing through a-conduit ill having a constriction therein, shown as being a Venturi tube II. The fiow of pressure fluid through the conduit i0 is controlled by a relay shown as having a controlimpulse receiving member, lever i2, pivotally 10 mounted at l3 and controlling the discharge of fluid from a port H by means of a baflle plate IS. The opening of the discharge port is a function of the space 8" between the bafiie plate and the port opening. i5

-The position of the control member-of the relay, the lever I2, is controlled by a primary impulse, such as a pressure acting within the diaphragm chamber Hi.

In opposition to the control impulse there is 20 shown to act upon the relay a secondary pressure-impulse taken at the throat of the Venturi tube and acting on a second diaphragm i'l within a diaphragm chamber R8. The size of this diaphragm determines the ratio between the pri- 25 mary impulses acting on the relay and the secondary impulses set up by the fluid at the throat of the Venturi tube. The smaller the diaphragm hood of a constriction in a conduit.

.A conduit l0 having a constriction in the form of an orifice plate 23 therein is tapped at points A, B and C and the pressure existing at these 5 points measured by gages 24, 25 and 26, The pressure in front of the orifice plate is indicated by ing decrease in pressure, l

sure limit is at about one-fifth of the pressureva'lue pa.

As diagrammatically indicated by the arrows,

the fluid is constricted to a narrow path when passing through the orifice plate, forming a so- I ing on the relative size of the orifice.

It has heretofore been the practice to connect the diaphragm chamber iii to a point C of the conduit I0. The characteristics of the relay of the known type are illustrated by the dotted curves in Figs. 3 and 4.

In Fig. 3 the ratio of the pressures upstream and downstream of the constriction is plotted against the stroke s of the battle plate. It is seen that for a closed discharge port, corresponding s=0 the pressure ratio will be 1.0. When the port is opened the ratio will gradually decrease according to the dotted line and approach the value .2. It-appears therefrom that even if there is no controlling impulse acting on the relay there will be a force exerted by the diaphragm l1, tending to maintain the port I4 open and resisting a change of this condition. Controlling impulses of a lesser magnitude than the force of the diaphragm I! will therefore have no eflect on the relay and not be converted into secondary impulses. The dotted line in Fig; 4 will-illustrate the foregoing.

In Fig. 4 the secondary impulses expressed in terms of pressure 121, are plotted against primary controlling impulses. It appears that at a controlling impulse of zero or small magnitude there will always be a' secondary impulse of the mag-.

nitude of .2 pressure unit, thereby rendering the relay nonresponsive to small control forces.

According to this invention the secondary impulses are taken at a point B within the "vena vcontracta" or suction-range of the constriction, as shown in Fig. 1.

Turning againto Fig. 3, it is easily understood that the pressure P2 will become zero, and even attain negative values when the pressure p, becomes a suction pressure as' indicated by the solid curve. correspondingly, the influence of the diaphragm I! on the control member will be zero and the secondary impulse zero when the control impulse is zero. This condition is illustrated by the solid curve in Fig. 4 extending to the zero point.

The operation of the relay shown in Fig. 1

will now be easily understood. Assuming a control impulse acting on the control member sud- The pressure acting on the denly becomes zero.

- diaphragm i! will at this instant tend to openthe port M thereby increasing the flow through conduit Ill. The increasing flow reduces the pressure existing within the range of the vena contracta Ill will be increased to cause a negative pressure to act on the diaphragm l1. thereby operating the relay to throttle the flow until is obtained. I

It is also apparent that if an upwardly directed impulse is applied to the relay lever an equal and oppositely directed force will be exerted by the diaphragm l1 and the gage 19 will .indicate suction pressure; I

A modified form of the relay is shown in Fig. 5. The conduit I0" is provided with a nonv'ariable constriction shown as being an orifice plate I I" and a variable constriction, or throttle, shown as being a gate-valve I5". sure impulse is takenat a point within the vena contracta or suction range of the orifice-plate II" to act in the same way on a diaphragm H" as hereinbefore explained. The device for exertthe zero position ing primary impulses on the lever I2" is not- The secondary presherein shown and described. Other types of flow resisting means may be employed than herein shown and described. The constant resistance offered by a long conduit may be utilized, for instance, as is well known in the art, or other changes may be made without departing from the scope of the invention. .Moreover,-it is not indispensable that all the features of the invention be used conjointly, since they may be. employed advantageously in various combinations and sub-combinations.

What is claimed is:

1. Pressure fluid relay comprising, in combination, a conduit having a discharge port; a constriction in said conduit; a member responsive to an outside-control impulse and arranged to vary the discharge from said port for varying the pressure within the suction range of said constriction in responseto said outside control impulse; and means responsive 'to a pressure taken at the suction range of said constriction and connected to act on said member in opposition to the controlling impulse.

2. Pressure fluid relay comprising, in combination, a conduit; a fixed constriction in said conduit; a variable constriction downstream of said flxed constriction; means responsive to an outside primary impulse for adjusting said variable constriction; and a secondary impulse pressure conduit connected to said flrst named conduit within the suction range of said fixed constriction,

-' whereby the secondary impulse pressure becomes a function of the primary impulse, ranging from suction pressure values upwards.

and a secondary impulse pressure conduit connected to said first namedconduit within the suction range of said fixed constriction, whereby the secondary impulse pressure'becomes a function of the primary impulse, ranging from suction pressure values upwards.

4. Pressure fluid relay comprising, in combination, a conduit: 9. fixed and a variable constriction'therein; means responsive to an outside primary impulse for adjusting said variable con striction; and a secondary impulse pressure conduit connected to said firstnamed conduit within the suction rangev of' theconstriction arranged upstream relatively to the second con- .becomes afunction of the primary impulse,

ranging from suction pressure values upwards.

5. Pressure fluid relay comprising. in combination, a conduit; a constriction in said conduit; a variable throttle in said conduit downstream or said constriction; means responsive to an outside primary impulse for adjusting said throttle; and a secondary impulse pressure conduit connected to the said first named conduit within the suction.

range ,of said constriction, whereby the impulse pressure becomes a function of the primary impulse.

6. Pressure fluid relay comprlsinain combination, a conduit having a discharge port; a constriction in said conduit; a movable baffle plate arranged to control the discharge of pressure fluid through said port, means responsive to an outside impulse and connected to move'said baille plate for varying the pressure within the suction range of said constriction said outside impulse; and means responsive to a pressure taken at the suction range oi. said constriction and connected to act on' said baflie plate.

'7. Pressure fluid relay comprising, in combination, a conduit; a Venturi tube in said conduit; a discharge throttle in said conduit; means responsive to an outside throttle for varying the in response to 7 control impulse and con-' tube in response to said control impulse;' and a diaphragm acted upon by a pressure taken at the throat of said Venturi tube and connected to act,

in opposition to said impulse means. i

8. Pressure fluid relay comprising, in combination, a conduit, an orifice plate in said conduit; adischarge throttle in said conduit; means responsive to an outside control impulse and connected to adjust said throttle for varying the pressure within the suction range of said orifice plate in response to said control impulse; and a diaphragm acted upon by a pressure taken at a point .01 the conduit within the vena constrictai created by said orifice plate and connected to act in opposition to said impulse means. 9. Pressure fluid relay comprising a conduit; a non-variableand a variable constriction therein; means responsive to an outside'primary im-,

pulse for adjusting said variableconstriction for.

varying the pressure within the suction range of said non-variable constriction in 'response to said primary impulse; and means responsive to a pressure taken at the suction range of said nonvariable constriction and connected to act in.

opposition to said impulse means whereby a pressure taken within the suction range or said nonvariable constriction becomes a function of the controlling impulse.

HERBERT ZIEBOLZ.

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