US1340241A - Liquid rheostat - Google Patents

Description

Patented May 18, 1920.

2 SHEETS-SHEET 1.

A. J. NICHT,JR.

LIQUID RHEOSTAT.

APPLICATION FILED. FEB. 1.1.. 1.916.

Patented May 18,1920.

2 SHEETS-SHEET 2.

UNITED STATES PATENT OFFICE.

ALEXANDER J. NIGHT, JR, OF MILWAUKEE, WISCONSIN, ASSIGNOR TO ALLIS- 'CHALMERS MANUFACTURING COMPANY, OF MILWAUKEE, WISCONSIN, A

CORPORATION OF DELAWARE.

LIQUID RHEOSTAT.

Original application filed January To all whom it may concern:

Be it known that I, ALEXANDER J. N orrr, Jr. a citizen of the United StateS, IeS1d1I1g at Milwaukee, in the county of Milwaukee and State of \Visconsin, have invented a certain new and useful Improvement in Liquid Rheostats, of which the following is a specification.

This invention relates in general to liqu d rheostats such as are generally useful in controlling the resistance of electrical clrcuits, and are of particular utility in controlling the operation of electric motors.

The present application is a (llVlSlOIl of application Serial No. 815,341, filed January 30, 1914, the latter appllca-tlon describing a system .of hoist control embodying a rheostat of the type which forms the subject matter of the present application.

It is an object of this invention to provide a liquid rheostat of improved construction.

It is a further object of this invention to provide a liquid rheostat of 1mroved construction wherein electrolyte 1s circulated through a reservoir compartment and an electrode-containing compartment, and wherein improved means are provided for controlling the immersion of the electrodes in the electrolyte.

These and other objects are attained by this invention, the various novel features of which will appear from the description and drawings, disclosing one embodiment of such invention, and will be particularly pointed out in the claims.

Figure 1 is a View in elevation, partly in section, of a rheostat and apparatus for controlling the same embodying features of this invention, the rheostat being shown as being connected in the secondary circuit of a polyphase induction motor. I

Fig. 2 is a view similar to Fig. 1, showing a modified form of this invention.

Fig. 3 is a fragmentary elevational view, showing an automatically operated valve and latch means therefor, forming a detail of the apparatus shown in Figs. 1 and 2.

Fig. 4 is a view in elevation of a movable weir or gate forming a part of the rheostat shown in Fig. 2.

Specification of Letters Patent.

30, 1914, Serial No. 815,841. ruary 11, 1916. Serial No. 78,047.

Fig. 5 represents a fragmentary Section on the line V-V of Fig. 2, but with the weir or gate in its upper position.

In the embodiment of the invention disclosed, the rheostat is of the polyphase type, such as ma be useful forjcontrolling the resistance 0 the secondary circuit of a polyphase, wound-rotor induction motor, here designated as M, and comprises a casing 30 divided by the partition 31, into two compartments 32 and 33. It is obvious that, instead of providing a single casing divided into a plurality of compartments, two separate casings might be used. The upper compartment or casing 32 is designed to con-' tain electrodes 34, 35, 36, in series with the polyphase circuit, as for instance, the secondary circuit of a motor. These electrodes may be of any suitable form, but each preferably consists of one or more metal plates spaced apart and rigidly secured in position. These electrodes are immersed in a body of resistance-liquid, preferably slightly acidulated water.

The lower compartment 33 of the casing 30 acts as a reservoir for liquid resistance material. A pump 37 driven by a motor 38, or any other suitable means, acts to force the resistance-fluid through the pipe 39 to the upper compartment 32.

It is obvious that the'resistance in the circuit to be controlled varies inversely as the amount of resistance-fluid in contact with the electrodes in the upper compartment. For varying the amount of such fluid and thus varying the resistance, one or more movable weirs 40, passing through the partition 31, are provided, which act as overflow passages to discharge fluid from the upper compartment to the lower supply compartment, the weirs being adjustable through the partition 31 to vary the level at which the resistance-fluid in the compartment 32 overflows, and, in their lowermost position, maintaining such a level of fluid that the electrodes are slightly immersed.

During the normal operation of a motor to be controlled, it is desirable that the pump 37 be continually operated to circulate the resistance fluid between the lower and upper compartments. The rate at which this circulation takes place may be varied by adjustin the valve 41, here shown asof the butter y type, in the communicating passage 39 ;With such system as is here described, fluid that becomes heated through use as a resistance element in the upper compartment 32 asses off at its upper level and is discha'r ed into the lower compartment 33. The ower compartment may be provided with a plurality of cooling pipes 42 through which air or other cooling fluid may circulate to assist in cooling the liquid in this compartment. The weirs 40 are operated by a pivoted lever 43, through a rod 44 connected to an operating member.

When the motor to be controlled is not in operation, only the lower ends of the electrodes'34, 35, 36, are immersed in the fluid resistance, the level of the fluid being lowest and the overflow weirs 40 being at their lowest point. With this condition existing, the resistance of the secondary circuit of the motor is a maximum. When the motor is started the weirs are lifted to their upper level and the pump 37 forces liquid into the compartment 32, gradually filling the same and decreasing the resistance inthe circuit, that is, the secondary of the motor, unt1l the level reaches the weir outlet, when the secondary is practically short-circuited. The motor then operates at its maximum speed. To stop the motor, resistance is first inserted in the secondary circuit by moving the weirs to their lower level and allowing the liquid to discharge to the lower compartment. When the liquid is at its lower level, the switch in the primary circuit of the motor may be opened, and, as little current is flowing therein, practically no arcing results.

In order to insure safe operation of a motor with which the rheostat is associated, and generally to incorporate in the apparatus an auxiliary controlling'device for the rheostat, means are provided for causing the discharge of fluid resistance from the upper compartment 32, independently of the weirs 40. This means comprises a by-pass 61, shown also in Fig. 3, between the compartments, the passage through which is normally obstructedby a valve 62, biased to open position by a weighted lever 63 and normally held 'closed by a latch 64, engaging a projection 65 on an operating handle 66 of the valve. The latch 64 is normally maintained in engagement with the projection 65, to hold the valve 62 in closed position, by an electromagnet 67, the latch 64 being mounted on the armature of said magnet. An adjustable stop 68 engages the handle 66 when the valve is open to limit the size of the discharge passage through the pipe This by-pass outlet 61 may be so disposed as to empty the upper compartment to any desirable extent, depending on what vm-ay be changed to anything desirable by providing the inlet to the by-pass with an extension that will permit emptying the tank to only the desired level.

Under normal conditions, as while the operation of the motor controlled b the rheostat is normal, the circuit of the atchholding magnet 67 is maintained closed in any sultable manner; and on the occurrence of any predetermined condition, as overload or when the load driven by the motor attains a desired condition, this circuit is opened, or the magnet is otherwise rendered ineffective to hold the. latch 64 in attracted position, thus tripping the latch and allowing the weighted lever 63 'to open the valve 62. Opening of this valve allows the discharge of electrolyte from the upper compartment and thus causes the insertion of resistance into the secondary circuit of the motor, slowing down the same. run at a gradually decreasing speed until the lower level is reached, at which liquid runs off through the by-pass 61. The motor may be allowed to run with resistance in the secondary circuit or it may be cut out by opening the primary switch.

' In order to hasten the insertion of resistance in the secondary circuit of the motor, as when the by-pass valve 62 is opened, the pump motor 38 may be caused to stop by breaking its circuit. A switch may be provided on the shaft of the valve 62, or arranged in any manner, to open when the valve opens. As shown in Fig. 1, a drum 131, having bridging contacts 132 and 133, is adapted to close two sides of a threephase pump-motor circuit by suitably bridging terminals of this circuit.

This switch may be operated by a chain, belt or gearing connection between the shaft of valve 62 and the spindle 134 of the switch, the connections being such as to render the pump 37 inactive when the valve 62 is open.

In Fig. 2, there is disclosed a modification of the rheostat shown in Fig. 1, the construction being such as better adapts the rheostat for quick insertion of resistance in the circuit to be controlled. The modified rheostat comprises a casing 130, divided by a tray-like partition 231, into upper and lower compartments 32 and 33, respectively.

The tray 231 is secured to the casing at three sides and the upper compartment is formed by the tray and the side walls of the casing and is closed at the fourth side by a movable partition or weir 90, which is separated from the fourth side of the casing, the general arrangement of the parts being such that the space between the fourth side of the casing and the movable partition or well 90 serves as 'an overflow passage to carry The motor will liquid from the upper to the lower compartment. This weir or gate is provided w th rollers 91, see Fig. 5, operatlng m guide ways 92, 93, secured to opposite sides of the age from the up or compartment, while the -'we1r is in any 0 its operative positions.

Theweir or gate .90 1s secured to a pivoted lever 94 to be operated thereby. Thls lever 94 is operated, through a rod 95, to raise the weir or gate 90, allowing the liquid that is forced into the upper compartment through the pipe 39, by the pump 37, to accumulate and thus reduce the secondary resistance of the motor and permit the same to pick up in speed.

The depth of the tray 23l is such that there is an appreciable amount of liquid retained in the tray and in contact with the lower ends of the electrodes 34, 35, 36, which project into the tray and always dip into the liquid contained therein. This construction also maintains the secondary circuit of the motor in closed condition, although the resistance of this circuit is quite high, when the weir 90 is lowered so that the only resistance liquid in, the upper compartment is contained in the tray, as at starting.

This type of resistance device may be provided with the same automatic discharge as is shown in connection with the resistance device illustrated in Fig. 1, in which a bypass 61 is provided with a valve 62, normally held closed by a latch 64 controlled by a novoltage magnet 67; and a switch, in the form of a drum 131, having bridging contacts 132 and 133 adapted to close two sides of a three-phase pump motor circuit,may be providedto openthe circuit of the pump motor when the valve 62 is opened. The drum 131 may be operated by a chain, belt or weir connection between the shaft of the valve 32 and the spindle 134 of the drum.

It will be apparent that, in case other than electrical means are used for driving the pump motor, suitable cut-ofi' means may be provided to operate in response to movement of the valve 62.

While the means for causing the slowing down of the motor under predetermined conditions, that is, independently of the operation of the weir or weirs at the will of the operator, is described as comprising a separate outlet from the upper compartment,

nevertheless, any apparatus capable of providing for the filling and emptying of this compartment in response to one type of control and of providing for the emptying of such compartment in response to the operation of a separate control effective under predetermined conditions, would accomplish the desired results; and, accordingly is to be considered as within the scope of this invention.

It should be understood that it is not desired that the invention claimed be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

It is claimed and desired to secure by Letters Patent I 1. A liquid rheostat comprising a casing, electrodes adapted to be immersed in liquid in said casing, manually operable means for varying the degree of immersion of said electrodes, and electromagnetically operative means for varying the degree of immersion of said electrodes.

2. A liquid rheostat comprising an electrode-containing compartment, means for discharging liquid resistance material into said compartment, means for controllin the discharge of liquid resistance material roin said compartment, and additional means for controlling the discharge of liquid resistance material from said compartment, said latter means comprising a controlling valve, means for holding said valve latched in closed position, and electromagnetically actuated means forcontrolling the operation of said valve.

3. A liquid rheostat comprising an electrode-containing compartment, a pump for forcing liquid resistance material into said compartment, means for controllin the discharge of said resistance material rom said compartment, and means operatively associated withsaid last mentioned means for controlling said pump.

4. A liquid rheostat comprising an electrode-containing compartment, a pump for forcing liquid resistance material into said compartment, a motor for driving said pump, means for controlling the discharge of resistance material from said compartment, and means operatively associated with said. last mentioned means for controlling the operation of said pump driving motor.

5. A liquid rheostat comprising an electrode-containing compartment, a reservoir compartment, a pump for forcing liquid resistance material from said'reservoir compartment to said electrode-containing compartment, means for controlling the discharge of resistance material from said electrode-containing compartment to said resercontrolling means as efi'ects an increase'in the discharge from said electrode-containing compartment.

G. A liquid rheostat comprising a casing, a partition dividing said casing into a pillrality of compartments one above a portion of another, said partition being spaced from a portion of the wall of said casing, a portion of that side of the upper compart-' ment adjacent the latter portion of the easing wall being in the form of a gate movable to constitute an adjustable overflow from said latter compartment to the other compartment.

7. A liquid rheostat comprising a casing, a partition dividing said casing into a p'lu rality of compartments one above another, said partition being spaced from the wall of said casing at one point, that side of the upper compartment adjacent the latter portion of the casing wall being provided with an adjustable gate constituting a weir permitting liquid to overflow from said upper compartment at different levels and to be discharged directly into the lower compartment.

8. A liquid rheostat comprising a casing, a partition in the form of a comparatively shallow tray dividing said casing into a plurality ofcompartments one above another, said partition being spaced from the wall of said casing at one point, a movable gate associated with said tray at said latter point and constituting an adjustable weir for the compartment formed at the upper side of said tray.

9. A liquid rheostat comprising a casing, means within said casing forming a compartment separate from the body portion of the casing, electrodes immersible in liquid resistance material within said compartment, a portion of the wall of said compartment being in the form of a gate adjustable to control the discharge of liquid resistance material from said compartment.

10. A liquid rheostat comprising an electrode-con-taining compartment, means for supplying liquid resistance material to said compartment, and instrumentalities for varying the degree of immersion of the electrodes in said compartment and including an adjustable weir operative to maintain the level of said liquid resistance material and permit overflow thereof at different points, and electromagnetically operable means effective to cause a lowering of the level of the liquid resistance material in said compartment independently of the position of said adjustable overflow weir.

11. A liquid rheostat comprising an electrode-containing compartment, and instrumentalities for circulating liquid resistance material through said compartment and maintaining the level of said liquid resistance material at different points therein during such circulation, and automatically actuatable means other than said aforesaid instrumentalities for controlling the discharge of liquid resistance material from said compartment.

12. A liquid rheostat comprising an electrode-containing compartment, means for supplying liquid resistance material to said compartment, means for controlling the discharge of said liquid resistance material from said compartment, and means operatively associated with said last mentioned means for controlling the supply of resistance material to said compartment.

13. A liquid rheostat comprising an electrode-containing compartment and a reservoir compartment, means for supplying liquid resistance material from said reservoir compartment to said electrode-containing compartment, means for controlling such supply of'liquid resistance material, a communicating. passageway being provided between said compartments by said means and permitting the discharge of liquid resistance material from said electrode-containing compartment to said reservoir compartment, and means for controlling such discharge compartment, said supply-controlling means and said discharge-controlling means being operatively associated for dependent operation whereby when said discharge-controlling means is actuated to permit discharge from said electrode-containingfrom said electrode-containing compartment the supply of liquid resistance material is substantially decreased.

14. In a liquid rheostat comprising an electrode-containing receptacle, means for controlling the degree of immersion of said electrodes, and electro-responsively actuatable means having control over the degree of immersion superior to said first named controlling means effective to cause a change in the degree of immersion of said electrodes independently of said first named controlling means.

15. A liquid rheostat comprising an electrode-containing receptacle, means for su plying liquid resistance material to said receptacle, and instrumentalities for varying the degree of immersion of the electrodes in said receptacle and including an adjustable weir operative to maintain the level of said liquid resistance material at desired points and permit overflow thereof, and electro-responsively actuatable means effective to cause a lowering of the level of the liquid resistance material in said rece tacle independently of the position of said adjustable Weir.

16. A liquid rheostat comprising at least two receptacles one of which is disposed to a desired extent within the other and has one side wall thereof spaced from a side wall of the other receptacle, said first named side wall constituting a weir over which liquid resistance material may discharge from one receptacle to the other, and means for varying the liquid level in said weirincluding receptacle.

17. A liquid rheostat comprising an upper electrode-containing receptacle and a lower reservoir receptacle. said receptacles having a number of walls in common, one of the side walls of said upper receptacle being spaced from a side wall of said lower receptacle, said first named side wall constituting a weir over which liquid resistance material may discharge from the upper to the lower receptacle and means for varying the liquid level in said upper receptacle.

18. A liquid rheostat comprising an upper electrode-containing receptacle, a lower reservoir receptacle, said receptacles having a number of walls in common, one of the said walls of said upper receptacle being spaced from a side wall of said lower receptacle, said first mentioned side wall c0n stituting a weir over which liquid resistance material may discharge, and means for causing a circulation of liquid resistance ma terial' between said upper and lower compartments. I

19. A liquid rheostat comprising a casing, a partition dividing said casing into a plurality of compartments a portion of one above a portion of another, said partition being spaced from a portion of the wall-of said casing, a portion of that side of the upper compartment adjacent the latter portion of the casing wall constituting a weir over which liquid resistance material may flow from said latter compartment to the other compartment.

20. A liquid rheostat comprising a casing, a partition dividing said casing into a plurality of compartments one above another,

said partition being spaced from the wall of said casing at one point, that side of the upper compartment adjacent the latter portion of the casing wall constituting a weir permitting liquid to overflow from said upper compartment and to be discharged directly into the lower compartment.

21. A liquid rheostat comprising a casing, a partition in the form of a comparatively shallow tray dividing said casing into a plurality of compartments one above another, said partition being spaced from the wall of said casing at one point, a wall associated with said tray at said latter point and constituting a weir for the compartment formed at the upper side of said tray.

22. A liquid rheostat comprising a casing, means Within said casing forming a compartment separate from the body portion of thecasing, electrodes innnersible in liquid resistance material within said compartment, a portion of the wall of said compartment constituting a. weir over which liquid resistance material may discharge from said compartment.

In testimony whereof the signature of the inventor is afiixed hereto.

ALEXANDER J. NIGHT, JR.

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