US1132777A - Automatic pressure-controller. - Google Patents

Description

C. S. JBNNINGS.

AUTOMATIC PRESSURE CONTROLLER.

APPLICATION FILED SEPT. 19, 190e.

Patented Mar. 23, i915.

y nUNIT-ED STATES PATENT FFXCEe CHESTER S. J'ENNINGS, 0F BROKLINE, MASSACHUSETTS, ASSIGNOR T0 THE LAMSON' comnNY, or NEWARK, NEW JERSEY,

A CORPORATION 0F NEW JERSEY.

AUTOMATIC PRESSURE-CONTROLLER.

Specification of Letters Patent.

Patented Mar. 23, 1915.

T0 all Iwhom z'tmag/ concern.'

lle it known that I, CHESTER S. JENNINGS, of Brookline, in the county of Norfolk and State of Massachusetts, have invented certain new and useful Improvements in Automatic Pressure-Controllers, of which the following is a specification.

My invention relates to power controlling apparatus, such for example, as may be used in a pneumatic despatch tube system to maintain a predetermined vacuum or pressure in the tubes. ln these despatch tube systems a blower or pump is employed to produce a Ipressure or vacuum in the transmission tubes, and the blower is driven by a motor whose speed is regulated so as to control the action of the blower or pump and maintain uniform or substantially unii'orm pressure in the system.

M v invention relates particularly to means for controlling the motor according to the pressure in the system. and its object is to produce simple and efiicient means to automatically control the action of the motor according to the pressure in the system with which the pump is connected.

l To these ends my invention consists of the combination with the air pump and an electric motor for driving the same, of a variable resistance in circuit with said motor and means for regulating this resistance in circuit with said motor and means for regulating this resistance comprising a pair of `auxiliary motors, one for increasing the resistance in the motor circuit and the other for diminishing the resistance in the motor circuit.'and means controlled by the pressure in the. transmission tubes or other chamber with which the pump is connected for selecting and operating one or the other oiisaid motors according to the variation of pressure in the tubes, so as to increase the resistance when the pressure varies in one direction. and to diminish the resistance when the pressure varies in the opposite direction.

Other features of. my invention are hereinafter pointed out.

1n the accompanying drawings in which' is illustrated a form of construction embodying my invention, Figure 1 is a diagram -of the device in connection with the supply pipe of a pneumatic despatch tube system; Fig. 2 is a plan view of the automatic controlling rheostat; Fig. 8 shows a section of the supply pipe of a pneumatic system showing diaphragm and switch connected therewith.

Like letters of reference refer to like parts throughout the several Views.

1 represents a blower adapted to exhaust air from or supply air to the supply pipe 2, which is here intended to represent part of a pneumatic despatch tube system.

3 is the electric motor which operates the pump l through the belt L1; 5 is the usual switch or rheostat that is used only in starting and stopping the motor 3. The circuit oi the field of the motor 3 is as follows: from the line wire 6 by wires T and 8 to one end of the Iield winding and from the other end of the field winding by wires 9 and lO to a series of resistances 11. Thence via a ratchet wheel 12 and wire 13 to the starting rheostat 5. and from the rheostat 5 by wire 14 to line wire 15. rThe circuit of the armature of the motor 3 is from the junction of wires 7 and S by the wire 16 to brush 17; through the armature and brush 18 to wire 19 and thence by a wire 2O to starting switch 5 where it joins the wire 14. The resistances 11 are connected with contacts Q1 which are in the path ot an arm Q2 carried by the ratchet 12. rlhis ratchet 12 is loose on a stud Q2 that also carries two arms 23 and Q4. The arms Q3 and 24 carry opposed pawls 25 and 25 to engage the ratchet 12 and as will be clear, when one of said arms is vibrated, the ratchet wheel 12 will be rotated step by step in one direction, and when the other of said arms is vibrated, the ratchet wheel will be rotated step by step in the opposite direction. The arm 23l is connected by a link 26a with a rod 2G, and said rod extends through a coil 27, the rod Q6 and coil Q7 constituting a solenoid. At its upper end. the rod Q6 extends into a cylinder 28 and has fastened to it a piston 29. The piston 29 and cylinder 28 constitute a dash pot to yieldingly resist or retard the movement of said rod. The piston is made with ports 30 through it for the passage of the contents within the cylinder from one side of the piston to the other as said piston moves with the rod. Also in order to provide Jfor regulating the resistance offered by the contents. the cylinder 28 is made with a. bypass 31 which is controlled by the valve screw 32. ln this way, the action of the dash pot may be regulated to control the speed of this auxiliary motor made up Vot the coil 27 and rod 26. rlhe coil 27 and cylinder 28 are fixed to the base plate 33, and .this base plate 33 also carries a pair of contacts 34 coperating with a bridge piece 35 carried by but insulated from a frame 36 on rod 26. IThis bridge piece is so adjusted that when the rod 26 is at its lowest point, the contacts 34 are connected, but when current iiows through coil 27, the rod 26 is lifted and the bridge piece 35 is carried away from contacts 34. The contacts 34 are in circuit with coil 27 and therefore the current is cut oli from said coil as soon as the rod 26 is lifted and the rod 26-iialls back to its lowermost position again, upon reaching which the bridge piece re'stablishes the connection between contacts 34 and the rod is again lifted.

The erin 24 is connected by a link 37 with a rod 33 extending1 through a coil 39 iXed to the plate `33 and projecting at its upper end into the cylinder 40. The rod 33 carries at its upper end a piston 4f. and said piston and cylinder 4U like the cylinder 28 and piston 23,*constitute a dash pot. Alongside ci coil 39 is a pair ci contacts 42 .fixed to plate 33 so as to cooperate with a bridge piece 43 carried by a trame 44eme rod 38'. The pipe 2 is cut away as at 45, and in this opening is iixed a diaphragm 46 pivoted at its middle 47 to a lever 43 pivoted at 49 to the frame 56 surrounding the opening 45. The lever 48 at one end carries two bridge pieces 5l and 52 and at its other end said lever is acted upon by the spring 53 whose pressure is adjusted by means or a screw 54 -so that when the predetermined normal vacuuin or pressure exists in the pipe 2, the lever 48 is balanced with the bridge pieces 5l and 52 out of engagement with the contacts 56, 57 58 and 59. The two contacts 56 and 53 are connected by the wires 60 and 7 with line wire 6, while contact 59 is connected by wire 61 with one ot the contacts 34. 'llhe other contact 34 is connected by wire 62-with one end 0i the Icoil 27. The other end of the coil 27 is connected by wires sa, et ana it with im@ wir@ i5. 'rile coatact 57 is connected by the wire 65 with one of the contacts 42 andthe other contact 42 is connected by the wire 66 with one end of the coil 39 the other end of said coil being `connected with the wire 64, which is in turn connected through the wire 14 with the line wire l5. lt will thus be seen that when the pressure in the pipe 2 varies in one direction, ythe contacts 56 and 57 will be connected and 39 and rod 38 will be reciprocated as above described so as to rotate the ratchet wheel l2 in a direction to increase the resistancein the circuit of the motor '3. llt will also be a circuit will be completed through the coil' seen when the pressure in the pipe 2 varies in the opposite direction, the bridge piece 52 will connect contacts 58 and 59 and the circuit will be completed throughA the coil 27 and rod 26 will be reciprocated as above described to rotate the ratchet wheel 12 in the opposite direction so as to reduce the re- Y sistance in the circuit of the motor 3.

There is thus provided a pair of motors, each of which actuates the ratchet l2 intermittently, that is, step by step, one serving to rotate said ratchet in one direction and the other serving to rotate said ratchet in the opposite direction. rlhe advantage ci this is that there is an interval of time between the step movements oi the ratchet l2 to allow the change of resistance in the circuit oie motor 3 to act through motor 3 and pump l on the pressure in the pipe 2 betore the resistance is again changed.

ln the constructions heretofore proposed, a rotating motor has been employed which was started, stopped and reversed to control the resistance in the circuit of the pun'ip driving,7 motor, but the objection to this construction `has been either that when the motor was stopped its momentum would carry it beyond the necessary point after its current was automatically cut oii" by the pressure in the pipe, or the like, or that the delay in overcoming the inertia oi the motor when started by the automatic pressurecontrolled means delayed the changing oi the resistance in the motor circuit. @n the other hand, this apparatus is quickly rei `sponsive to any kchange or pressure in the pipe 2 beyond a predetermined point and the resistance in the circuit of the motor is accurately varied according to changes or? pressure in pipe 2.

Having thus described the nature or nay invention and set orth a construction ernbodying the same, what claim as new and desire to secure by Letters lpatent ci the United States is:

l. ln an automatic pressure controller, the combination oi an air-transmission tube, a pump communicating with said tube, an electric motor for driving said pump, a variable resistance in circuit with said motor, and .means for regulating' .the resistance o said motor circuit comprising` two auxiliary motors with one acting to increase the resistance in said circuit and the other for diminishing the resistance in said ciry cuit, and means controlled from substantially but a single point by the pressure in said air-transmission tube for selecting and singly operating one or the other of said auxiliary motors according to the variation oi pressure in said tube, so that one of said auxiliary motors when selected will increase the resistance in said circuit when the pressure varies in the tube in one direction, and the other oi said auxiliary motors when lll@ selected will diminish the resistance in said circuitwhen the pressure in the tube varies in the other direction.

2. Inan automatic pressure controller, the combination of an air-transmission tube, a pump communicating with said tube, an electric motor for driving said pump, a variable resistance in circuit with said motor, and means for regulating the resistanceV of said motor circuit comprising two auxiliary motors with one substantially invariably acting, Whenever operative, to increase the resistance in said circuit and the other for similarly diminishing theresistance in said circuit, and means controlled by pressures in said air-transmission tube of but one sign, atmospheric pressure being regarded as zero for the purpose of determining said sign, said means adapted to select and operate one or the .other` of said auxiliary motors according to the change of pressure in said tube either Way from a determined normal pressure to be maintained therein, so that one of said auxiliary motors when selected will increase the resistance in said circuit when the pressure varies 1n the tube in one direction, and the other of said auxiliary motors when selected will d1- minish the resistance in said circuit when the pressure in the tube varies in the other direction.

3. In an automatic pressure controller, the combination of an air-transmission tube, a pump communicating with said tube, an electric motor for driving said pump, a va riable resistance in circuit with said motor, and means for regulating the resistance of said motor circuit comprising two auxiliary motors with one acting to increase the resistance in said circuit and the other for diminishing the resistance in Ysaid circuit, and means controlled by the pressure in said air-transmission tube for selecting and operating one or the other of said auxiliary motors while leaving the other idle, according to the variation of pressure in said tube, so that one of said auxiliary motors when selected will increase the resistance in said circuit when the pressure varies in the tube in one direction, andthe other of said auxiliary motors when selected will diminish the resistance in said circuit when the pressure in the tube varies in the other direction, said motors having provisions for gradually varying said resistance substantially regardless of violent and sudden variations in pressure in said tube.

4. In an automatic pressure controller, the combination of an air-transmission tube, a pump communicating with said tube, an electric motor for driving said pump, a variable resistance in circuit with' said motor. and means for regulating the resistance of said motor circuit comprising two auxiliary motors, independently driven with respect to said pump, with one acting to increase the resistance insaid circuit and the other for diminishing the resistance in said circuit, and means controlled by the pressure in said air-transmission tube for selecting and operating one or the other of said auxiliary motors according to the variation of pressure in said tube, so that one of said auxiliary motors when selected will increase the resistance in said circuit when the pressure varies in the tube in one direction, and the other of said auxiliary motors when selected will diminish the resistance in said circuit when the pressure in the tube varies in the other direction.

5. In an automatic pressure controller, the combination of an air-transmission tube, a pump communicating with said tube, an electric motor for driving said pump, a variable resistance in circuit with said motor, and means for regulating the resistance of said motor circuit comprising two auxiliary motors with one acting to increase the resistance in said circuit and the other for diminishing the resistance in said circuit, and a device controlled by the pressure in said air-transmission tube for selecting and operating singly one or the other of said auxiliary motors according to the variation of pressure in said tube, so that one of said auxiliary motors when selected Will increase the resistance in said circuit when the pres- Y sure varies in the tube in one direction, and the other of said auxiliary motors when selected will diminish the resistance in said circuit when thevpressure in the tube varies in the other direction.

In testimony whereof, I have signed my name to this specification in the presence of two subscribin witnesses, this fifteenth day of September D. 1906.

CHESTER S. J ENNINGS.

Witnesses:

HOWARD R. DUNBAR, H. D. WATERHoUsE.

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