US1293697A

US1293697A - Overload device.

Info

Publication number: US1293697A
Application number: US9222116A
Authority: US
Inventors: Harry R Canfield
Original assignee: Electric Controller and Manufacturing Co LLC
Current assignee: Electric Controller and Manufacturing Co LLC
Priority date: 1916-04-19
Filing date: 1916-04-19
Publication date: 1919-02-11
Anticipated expiration: 1936-02-11

Description

H. R. CANFIELD'.

OVERLOAD DEVICE.

APPLICATION FILED APR-19,1916.

1,293,697; Patented Feb. 11, 1919.

INVENTOR War/y FR Camf/e/c/ Z m @MZW All'y,

hiing and inspection.

HARRY P... GARFIELD, OF CLEVELAND, OHEO, ASSIGZEQI'L '1@ THE & MANUFACTURING COMPANY, OF CLEVELAND, OHIQ, CORPOMIIQZZ' @F GELIG.

ovnanonn nnvrcn.

Specification of Letters Batent.

Patented Felon ill, 1919..

Application filed April 19, 191%. Serial l lo. 88,281.

overload devices, and particularly to those having time-interval features.

The principal object of this invention is to provide an overload device, the operation of which is delayed for an interyal of time after the occurrence of the overload, if the overload is'less than the predetermined amount, and which, on excessively high or dangerous overloads, operates instantaneously. Another object is to provide an overload de'vicein which the time-interval elements are hermetically sealed in a container to exclude dust, dirt, moisture, etc. Other objects will be apparent from the following specification.

lln the accompanying drawing, Figure l is a cross-sectional view of one form of my invention; 2, a cross-sectional view showing a modification thereof; and Fig. 3, a partial cross-sectional view or" another modification.

Referring to Fig. l, 11 is a winding energized by current in a controlled circuit, not shown. it) is a main magnetic "frame containing the winding ll and having a removable pole-piece 12 to facilitate assem- 13 is a magnetic plunger which is attracted toward the polepiece 12 icy magnetic flux across the ap 14 when the winding 11 is energized, The lower threaded end or" the plunger is screwed into the upper end of the hollow cylinder 15 oi preferably non-ma 1 etic material. The upper end of the p ung'er 13 may be hexagonal or square to receive a wrench. By means of the flange 16 on the plunger and the packing washer 17 between the flange and the cylinder 15, the cylinder is hermetically sealed when the plunger is screwed into it. The lower end of the cylinder 15 rests on an adjustable pedestal 19 threaded into a bracket 20 attached to the magnetic frame 10, so that, by adjusting the pedestal, the length of the air-gap 14 may be varied. Within the cylinder 15 is the magnetic piston .21, immersed or partly immersed in a heavy liquid 22, such as mercury or a heavy basic solution. The piston 21 is preferably cylindrical with a small clearance between its circumference and the wall of the cylinder 15, and has the inter or cavity 23, in general cone-shaped terminating at the-up or end in the smal onfice 36. Between tile piston 21 and the plunger 13 is another magnetic air-gap 30.

o The plunger 13carries the upwardly pro- ]ect1ng'stem 24 for engaging the switcharm 25 to open the

contacts

26 and 2?, which may thereby interrupt the circuit including the

wires

28 and 29 for controlling a circuitbreaker, not shown.

'The operation of the device shown on Fig. l is as follows: When an overload of small or ordinary value occurs in the ding ll, flux is generated thereby in the n frame 10, the piston 21, the gap plunger; 13, the gap 1 2, and the ol This flux in the gap 1 2- exerts a pull on the plunger 13, and the i gap 30' exerts an upward pull on 21. The ilux in the gap 14 is ins lift the plunger 13 and the der l5 and its contents, ,0.- gap 30 is sufiicient to lift the pist moves slowly and uniforml ill straining action oi the liquid 22. upward movement of the piston cc to emerge from the liquid and to l portion of the liquid in the interic 23. The weight of this portion of balances the magnetic pull in the L causing the upward movement of the pistor 21 to cease. The air above the piste then passes through the orifice 36, allow the level of the liquid in the cavity 23 to so slowly lowered. The weight of the liquid supported by the piston 21 becoming less, the piston again moves upwardly. This action continues, resulting in a slow upward movement 0:5 the piston 21, the rate dependmg upon the amount of magnetic pull in the gap 30 and the size of the orifice 36. The a movement of the piston 21 is further steadied by the restricted flow of liquid and air downward between. the piston and the wall of the cylinder. As the piston moves upward the magnetic reluctance of the gap 30 is gradually reduced, and more and more fiux flows through the entire magnetic circuit. The pull on the piston 21 in the gap 30. therefore, increases and tends to so celerate the movement of the piston 21, but 1143 movement,

this tendency is counteractedfby so shaping the interior cavity 23 that as the p ston moves upward the weightof the liquid lifted in a given unit distance will ncrease with the upward movement of the piston proportionately to the increase of magnetic pull, resulting in a uniform movement of the piston. However, I do not limit my invention to any definite shape of this cav1t When the piston 21 has approximate y reached the plunger 13, the reluctance of the entire circuit has been decreased sufficiently to 've suficient flux 1n the gap 14 to lift the p unger 13, carryin with it the cylinder 15v and its contents, w ereupon the stem 24 engages the arm controll ng circuit of thecircuit breaker, as described.

If the overload in the winding 11 is somewhat greater than that assumed 1n the case will be eater and the piston 21 will travel upward y with reater rapidity, and before it has reached t e plunger 13, the fiux 1n the gap 14 will lift the plunger 13 andopen the switch 25, andconsequently the circuit breaker. If, however, the overload in the winding 11 is excessively high or dangerously large, the flux in the gap 1 1 Wlll be sufiicient to lift the plunger 13 together with the cylinder 15, the piston 21, and the liquid 22 at once without awaiting the independent movement of the piston 21. The reater the current in the winding 11, the aster w ll the piston move at any given point of its due to its lifting a greater weight of liquid .a'nd to the greater rapidity with which the air will flow through the orifice 36, and hence the shorter will be the time-interval between the overload and operation.

By adjusting the pedestal 19 the length of the gap 14 may be adjusted to change the values of current in the coil 11 at which the device will operate. It will be understood, of course, that the relative positions of the plunger 13 and the piston 21 may be varied, as desired, by varying the length of the cylinder 15. I

In the device shown in Fig. 2, an adjustable oleepiece 31 is provided to introduce another gap 32 between the pole-piece 31 and the lower end of the piston 21. The pedestal 19 is in this case threaded in the pole-piece 31. y

In the operation of the device shown in Fig. 2, the current in the winding 11 generates fiux in the magnetic frame 10, the adjustable pole-piece 31, the air-gap 32, the piston 21, the air-gap 30, the plunger 13, the air-gap14, and the pole-piece 12. The function of the gap 14 is the same as that described in connection with Fig. 1. The

' flux in the

gaps

30 and 32 pull in opposite directions on the piston 21" the fil X th 25, openingthe described, the fiux in the entire circuit 7 gap 30 predominating, so that the piston 21 moves upwardly. As the upward movement of the piston, 21 decreams the reluctance in the gap 30, it increases the reluctance in the gap 32, so that the flux in the entire circuit does not increase as rapidly as in the case of Fig. 1, and the movement of the piston 21 is not so rapidly accelerated. The compensating eilect of the hollow cavity in the iston 21 shown in Fig. 1, ma be omitted, if desired, and the piston ma e solid. To steady the movement of the piston, any suitable liquid 22 may be used and a small clearance allowed between the piston and the wall of the cylinder.

In Fig. 3 are shown the movable parts only of another form in which no liquid is used. The piston 21 is provided with the suction washer 33 and t e adjustable airport 34. A. downwardly-projecting guide 35, preferably non-magnetic, is provided on the plunger 13 to centrally guide the iston 21". When the flux in the gap 30 lifiis the piston 21, the air above the piston moves through the port 34 and the space below the piston and retards the upward movement of the piston, the operation of the rest of the device being the same as of that shown in Fig. 1.

t is apparent from the foregoing that other means than that shown for retarding the upward movement of the magnetic piston 21 in the cylinder 15 may be employed within the scope of my invention; that other adjustment features may be employed; that the shape of the interior cavity 23' of the piston 21 may be modified to control the rate of movement of the piston 21 as desired; and that other changes may be made without departing from the spirit of my invention.

I claim- 1. In an electromagnetic device, a winding, a casing and a magnetic member therein both influenced by current in the winding to move when the current is above a predetermined value, and means including means within the casing whereby the said movement of the casing is delayed by a time interval inversely proportional to the rate of movement of the magnetic member.

2. In an electromagnetic device, a winding, a casing and a magnetic member therein both influenced by current in the winding to move when the current is above a predetermined value, and means including a fluid in the casing whereb the said movement of the casing is delaye by a time interval inversely proportional to the rate of movement of the magnetic member.

3. In an electromagnetic device, a winding, a casing and a magnetic member therein both influenced by current in the winding to move when the current is above a predetermined value, and'means including means within the casing whereby the said movement of the casing is delayed by a time interval which is inversel proportional to the rate of movement of the magnetic member andwhich is decreased by an increase of current in the winding.

4. In an electromagnetic device, a winding, a casin and a magnetic member therein both influenced by current in the winding to move. when the current is above a predetermined value, and means including a fluid '-i n the casing whereby the said movement of the casing is delayed by a time interval which is inversely proportional to the rate of movement of the magnetic member and which is decreased by an increase of current in the winding.

5. In an electromagnetic device, a winding, a casing and a magnetic member therein both influenced by current in the winding to move when the current is above a predetermined value, means in the casing whereby the said movement of the magnetic member is retarded, and the movement of the casing is delayed until after the movement of the magnetic member except when the current is above a second higher predetermined value. 4

6. In an electromagnetic device, a winding, a casing and a magnetic member therein both influenced by current in the winding to move when the current is above a predetermined value, and means including a fluid in the casing whereby the said movement of the magnetic member is retarded, and the movement of the casing is delayed until after the movement of the magnetic member except when the current is above a second higher predetermined value.

7. In an electromagnetic device, a mag- 40 netic circuit, a winding therefor, a movable member in the circuit influenced by current in the winding to move when the current is above a predetermined-value, and means for delaying the said movement of the member for a time interval the said means comprising a movable element in said magnetic circuit having a dashpot connection with the said movable member 8. In an electromagnetic switch, a mag- 5 netic circuit, a winding therefor, a movable member in the circuit influenced by current in the winding to move when the current is above a predetermined value, means for delayingthe said movement of the member for a time interval, the said means comprising a movable element in the magnetic circuit hermetically sealed within the movable member and movable relatively thereto, and means for retarding the relative movement.

9. In an electromagnetic switch, a mag netic circuit, a winding therefor, a movable member in the circuit influenced by current in the winding to move when the current is above a predetermined value, means for delaying the said movement of the member for a time interval except when the current is above a second predetermined value, the said means compnsing a movable element In the magnetic circuit hermetically sealed within the movable member and movable relatively thereto, and means for retarding the relative movement.

10. In an electromagnetic device, a magnetic circuit, a winding therefor, a movable member and a movable element in the circuit both influenced by current in the winding to move when the current is above a predetermined value, the movable member constituting a container-for the movable element, and means whereby the said movement of the movable member is delayed until the reluctance of the circuit has been reduced by the movement of the element except when the current is above a second predetermined value.

11. In an electromagnetic device, a winding therefor, two movable members forming the two elements of a dashpot and both influenced by current in the Winding to movewhen the current is above a predetermined value, and means including a magnetic circuit of variable reluctance, whereby the said movement of one member is delayed until after the said movement of the other except when the current is above a second predetermined value.

12. In an electromagnetic device, a magnetic circuit, a winding therefor, and two movable members in the circuit both influenced by current in the winding to move when the current is above a predetermined value, the two members forming the two elements of a dashpot, and means whereby the said movement of one member is delayed 10 until the reluctance of the circuit has been reduced by the said movement of the other members, except when the current is above a'second predetermined value. v

13. In an electromagnetic device, a winding therefor, a movable member influenced by current in the winding to move when the current is above a predetermined value, the movable member having a chamber movable therewith and a movable magnetic element in the chamber, having a dashpot connection with the chamber, and means including a magnetic circuit, the reluctance of which varies on the movement of the movable element, whereby the movement of the member is delayed until after the movement of the element, except when the current is above a second predetermined value.

14. In an electromagnetic device, a magnetic circuit, a winding therefor, a movable member in the circuit influenced by current in the winding to move when the current is above a predetermined value, the member having a hermetically sealed chamber movable therewith, a magnetic element of the 189 magnetic circuit in the chamber, and means whereby the said movement of the member is delayed until after the movement of the element except when the current is above a second predetermined value. Q 15. In an electromagnetic device, a winding, a movable chamber-member influenced by current in the winding to move when the current is above a predetermined value only, and means for 'delaying the movement of the chambef-member for a time interval, the said means comprising a movable element hermetically sealed within the chambermember. s q

16. In an electromagnetic device, a magnetic circuit, an energizing winding, a member adapted to be moved upwardly by the magnetic influence of the winding, and

means for retarding the movement of the member, comprising a body of liquid in which the member is positioned, the said member having therein a cavity communinetic circuit, an energizing winding, a wor ing gap in the circuit, a member adapted to be moved upwardly by theforce of magnetic flux in the gap, the force increasing with the movement ofthe member, means or retarding the movement of the member, com prising a body of liquid in which the member is positioned, the said member having therein an upwardly tapering cavity communicating below with the liquid and having a restricted orifice above, the sha e of the cavity and the size of the orifice eing such that the weight of the member and the occluded liquid balances the variable magnetic pull during the upward movement of the member.

Signed at Cleveland, Ohio, this 14th day of April, A.

HARRY R. OANFIELD.