US2075463A - Heater - Google Patents

Heater Download PDF

Info

Publication number
US2075463A
US2075463A US740113A US74011334A US2075463A US 2075463 A US2075463 A US 2075463A US 740113 A US740113 A US 740113A US 74011334 A US74011334 A US 74011334A US 2075463 A US2075463 A US 2075463A
Authority
US
United States
Prior art keywords
heating
wire
armature
space
circuit
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US740113A
Inventor
Robert J Parsons
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Consolidated Car Heating Co Inc
Original Assignee
Consolidated Car Heating Co Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Consolidated Car Heating Co Inc filed Critical Consolidated Car Heating Co Inc
Priority to US740113A priority Critical patent/US2075463A/en
Application granted granted Critical
Publication of US2075463A publication Critical patent/US2075463A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24HFLUID HEATERS, e.g. WATER OR AIR HEATERS, HAVING HEAT-GENERATING MEANS, e.g. HEAT PUMPS, IN GENERAL
    • F24H3/00Air heaters
    • F24H3/02Air heaters with forced circulation
    • F24H3/04Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element
    • F24H3/0405Air heaters with forced circulation the air being in direct contact with the heating medium, e.g. electric heating element using electric energy supply, e.g. the heating medium being a resistive element; Heating by direct contact, i.e. with resistive elements, electrodes and fins being bonded together without additional element in-between

Definitions

  • This invention relates to electricity, particularly to heating by electricity, and more especially to forced draft heating.
  • heating systems take many forms, but they are quite often of a form which includes a fan for causing a flow of air over the heating element. It is also well known that the heating element generates so much heat that if the flow of air thereover ceases, there is great danger of burning out the heating element.
  • the principal object of this invention is to provide an arrangement of heating units and means for causing a flow of air thereover such that the heating element will be deprived of heating energy upon the cessation of the flow of air thereover.
  • Figure l is a schematic or diagrammatic view of an arrangement of heating units and air movement means arranged in accordance with 5 applicants invention
  • Fig. 2 is a modified form of the device as shown by Fig. 1
  • Fig. 3 is a further modification of the device of Fig. 1 in that it shows means for varying the flow of air over the heating units.
  • numeral I designates a conductor connected to a source of potential. This conductor I is connected to conductor 2 by means of a manually operable switch 3. When this switch 3 is in the closed position, current flows through wire I, switch 3, wires 2 and 4, limit- 1934, Serial No. 740,113
  • a thermostat 31 preferably of the well known sylphon type, operating a bridge 38 which bridges contacts 39 and 40 when the thermostat 31 is subjected to a temperature too high in degree.
  • the bridging iember 38 bridges the contacts 39 and 40 the current which formerly flowed from wire 6 through wire I to energizing coil 8 and the relay would then flow through wire 4
  • Ihe arrangement as shown in Fig. 2 varies from that shown in Fig. l in that the energy of the heating coil does not pass through the armature of the relay corresponding to the relay whose energizing coil is 8 in Fig. 1.
  • the motor armature l5 bridges the contacts 25 and 25 so that then current will flow from the positive terminal of the source of potential through wire i, switch 3, wires 44 and 65, through lii l resistance 46 to contact 25, bridge 26, contact 25, wire 38, energizing coil 3!, wire 32 to ground id.
  • Fig. 2 is th same in construction, operation, and function as 1.
  • the bridging contact 2d bridges contacts 25 and 28 so that current then flows as follows: positive terminal of the source or" potential, wire l, switch 3, wires 48, and 5, limiting resistance 57, contact 26, bridge 25, contact 25, wire 38, energizing coil 3i and wire 32 to ground l5.
  • Current flowing in the above traced path will cause the armature 34 to be raised so that then current may flow from the wire 33 through wire 53, armature 34, wire 59 and through heating units 53 and 54 and thence to ground iii.
  • bridging member 68 would allow current to flow from the posi tive terminal of the source of potential as follows: positive terminal of the source of potential,
  • the thermostat 3l' is arranged in the space A, to be heated and is so adjusted that its bridging member 38 contacts 39 and 4&3 only when the thermostat has been subjected to the heat obtained by blowing air over all of the heating units 53, 54, 55 and 56 at a time when all of them have current flowing therethrough, then when the space A has arrived at the proper high heat the bridging member 38 bridging contacts 39 and ill will short circuit the energizing coil 64 of the relay and cause the armature 5'! and the bridging member 68 to fall, the one breaking contact with wire 59 and the other breaking contact with the contacts l2 and i3.
  • the method of heating hereinbeiore described is applicable to any situation where a space must be heated but is particularly applicable to the heating of vehicles propelled by electricity because in such case the electrical energy is available as it may be taken from the same source as that which propels the vehicles.
  • a heating unit in combination: a heating unit; a selectively operable second heating unit; a motor; means operated by the motor for causing a flow of air over both of the heating units; means for suppiying electrical energy to the motor including a resistance in series therewith; a circuit closing and opening device and means operable exclusively by said motor to open and close said device; means for causing a flow or" electricity through the first of said heating units including the said circuit closing and opening device; means for causing a flow of electricity through the second mentioned heating unit controlled by the last mentioned means; and means for causing a flow of electricity through said motor through less than all of the said resistance when said second heating unit is in operation whereby the motor operates at increased speed and causes a greater flow of air over said heating units.
  • electrical heating unit a fan rotatable relative to said unit for causing movement of air over said heating unit; means for operating said fan; and means operable exclusively by said fan-opcrating means and only while said fan is operating for causing a flow of electrical energy through the said heating unit; a space to be heated; a thermostat in said space; and means controlled by the thermostat for governing the operation of the fan and so the flow of electricity through the heating unit.
  • a heating system in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means.
  • a heating system in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of an other electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted to close
  • a heating system in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermo static device adapted to establish and break saidshunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of another electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted to close said control
  • a heating system in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of another electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted "to close

Description

March 30, 1937 R. J. PARSONS HEATER Filed Aug. 16, 1934 f. ATTORNEY W ;IN%ENTOR X Patented Mar. 30, 1937 UNITED STATES PATENT OFFICE to Consolidated Car- Heating Company, Inc.,
Albany, N. Y., a corporation of New York Application August 16,
6 Claims.
This invention relates to electricity, particularly to heating by electricity, and more especially to forced draft heating.
It is well known to those skilled in this art that vehicles propelled by electricity are generally also heated by electricity. The heating systems take many forms, but they are quite often of a form which includes a fan for causing a flow of air over the heating element. It is also well known that the heating element generates so much heat that if the flow of air thereover ceases, there is great danger of burning out the heating element.
The principal object of this invention is to provide an arrangement of heating units and means for causing a flow of air thereover such that the heating element will be deprived of heating energy upon the cessation of the flow of air thereover.
Other objects and advantages will appear as the description of the particular physical embodiments selected to illustrate the invention progresses, and the novel features will be particularly pointed out in the appended claims.
In describing the invention in detail and the particular physical embodiments selected to illustrate the invention, reference will be had to the accompanying drawing and the several views thereon, in which like characters of reference designate like parts throughout the several views, and in which:
Figure l is a schematic or diagrammatic view of an arrangement of heating units and air movement means arranged in accordance with 5 applicants invention; Fig. 2 is a modified form of the device as shown by Fig. 1; Fig. 3 is a further modification of the device of Fig. 1 in that it shows means for varying the flow of air over the heating units.
In Fig. l, numeral I designates a conductor connected to a source of potential. This conductor I is connected to conductor 2 by means of a manually operable switch 3. When this switch 3 is in the closed position, current flows through wire I, switch 3, wires 2 and 4, limit- 1934, Serial No. 740,113
through wire I2, armature II, wire I3, wire I 4, resistance I5, armature I6 and field I! to ground i8. Current flowing in the above traced path will cause the armature I6 of the motor to rotate. Upon a rotation of the armature I6, the 5 fan blades I9 will cause a flow of air over the heating units 20, 2 I and 22 and at the same time cause the fly balls 23 of the fiy ball governor to fly outwardly and move contact member or bridge 24 into contact With contacts 25 and 2B. As soon as these contacts 25 and 26 are bridged by bridging member 2 3 current may then flow as follows: from the positive terminal of the source of potential, wire I, switch 3, wires 2 and I2, armature Ii, wires I3, 2'! and 28, resistance 29, contact 25, bridge 24, contact 25, wire 30, relay energizing coil 3| and wire 32 to the negative terminal of the source I0.
Current flowing in the above traced path raises armature 34 so that then current may flow from wire 27, through wire I8, armature 34, wire 35, and through the three heating units 28, 2| and 22 to the negative terminal of the source I0.
From the above description it will be seen that only after the armature I6 has started to rotate and the fan blades I9 are delivering air over the heating units 2i), 2I and 22 is the relay coil 3I energized so that its armature 34 is raised so as to supply electrical energy to the heating units 29, H and 22. This being so, it is readily seen that it is impossible to overheat the heating units 20, 2i and 22 because at times when electrical energy is flowing therethrough, the fan blades I9 are forcing air thereover so as to keep the temperature down to the proper value. 35
As the air passing over the heating units 20, 2i and 22 is for heating a space such as space A, applicant positions therein a thermostat 31, preferably of the well known sylphon type, operating a bridge 38 which bridges contacts 39 and 40 when the thermostat 31 is subjected to a temperature too high in degree. When the bridging iember 38 bridges the contacts 39 and 40 the current which formerly flowed from wire 6 through wire I to energizing coil 8 and the relay would then flow through wire 4|, contact 40, bridge 38, contact 39 and wire 42 to the negative terminal III of the source so that the relay armature II would fall becoming disconnected from wire I2. Upon de-energization of the relay whose energizing coil is 8 the motor would be cut off from the source of potential and consequently the heating coils would also be cut ofi from the source of potential. When the temperature of Cir the space A is sufiiciently lowered the thermostat 37 will withdraw the ridge 38 and the relay whose energizing coil is 3 will again raise the armature ii and the parts will function as before.
Ihe arrangement as shown in Fig. 2 varies from that shown in Fig. l in that the energy of the heating coil does not pass through the armature of the relay corresponding to the relay whose energizing coil is 8 in Fig. 1. In Fig. 2, after the switch has been closed, and the relay coil 8 has been energized, the motor armature l5 bridges the contacts 25 and 25 so that then current will flow from the positive terminal of the source of potential through wire i, switch 3, wires 44 and 65, through lii l resistance 46 to contact 25, bridge 26, contact 25, wire 38, energizing coil 3!, wire 32 to ground id. The flow of current in the above traced path energizes the relay so that armature 34 is raised and then the heating units 2i and are energized by current which flows in a path as follows: positive terminal or" the source of p tiai, wire 5, switch 3, wires :4, and armature 34 and wire 35 to heating units 23, El and 22 and thence to ground l0.
Other than the fact that the heating energy is not taken through the relay whose energizing coil is 8, Fig. 2 is th same in construction, operation, and function as 1.
In Fig. 3 provision has been made to supply heat to the space to be heated, but at lower rate, even after the thermostat 3i has bridged the contacts 39 and In Fig. 3 when switch 3 has been manually closed, current flows from the positive terminal of the source of potential by wire I, the switch 3, wires 55, i9 and 58 to two part resistance 5! and 52, armature l 6, field ll, to ground l 0. Currrent flowing in the above traced path will cause the armature iii to revolve and the fan blades is to force air over the heating units 53, 54, 55 and 56.
When the armature i6 revolves, the bridging contact 2d bridges contacts 25 and 28 so that current then flows as follows: positive terminal of the source or" potential, wire l, switch 3, wires 48, and 5, limiting resistance 57, contact 26, bridge 25, contact 25, wire 38, energizing coil 3i and wire 32 to ground l5. Current flowing in the above traced path will cause the armature 34 to be raised so that then current may flow from the wire 33 through wire 53, armature 34, wire 59 and through heating units 53 and 54 and thence to ground iii.
Under the conditions just described, the armature is being fed through both resistances 5| and 52 would revolve at a speed which we may designate as a lower speed and at the same time only two of the heating units 58 and 54 would be energized, but at the same time current would flow through armature 3 from wire 38 through wires $0 and 6!, limiting resistance 62, wire energizing coil 55 and wire 65 to ground Ill. Current flowing in the last traced path causes armature 67 to be raised and also armature or bridging member 58.
When armature 67 is raised then current can flow from the positive terminal of the source through wire i, switch wires 48 and 58, armature El, wire iii, through heating coils 55 and 55 and then to the negative terminal of the source through ground ill, thus energizing all of the heating units. At the same time, bridging member 68 would allow current to flow from the posi tive terminal of the source of potential as follows: positive terminal of the source of potential,
wire I, switch 3, wires 43, 49, 50 and H, contact 72, bridge 68, contact 73, wire M to resistance 52 and then through armature l5 and field ll to ground ill. The effect would be that the motor would be fed by a current all of which did not pass through both of the resistances 5i and 52, that is, the resistance between the source and the motor would be largely decreased. The effeel; would be that the motor armature would move at a very much higher speed and the fan blades 59 would move at a higher speed so that While all of the heating units 53, 54, 55 and 5B are energized more air would be passed over them.
If the thermostat 3l' is arranged in the space A, to be heated and is so adjusted that its bridging member 38 contacts 39 and 4&3 only when the thermostat has been subjected to the heat obtained by blowing air over all of the heating units 53, 54, 55 and 56 at a time when all of them have current flowing therethrough, then when the space A has arrived at the proper high heat the bridging member 38 bridging contacts 39 and ill will short circuit the energizing coil 64 of the relay and cause the armature 5'! and the bridging member 68 to fall, the one breaking contact with wire 59 and the other breaking contact with the contacts l2 and i3. When this occurs, the motor will then be fed through both of the resistances 5i and 52, the armature will revolve at the lower speed and the electrical energy will be cut off from the heating coils 55 and 56. When the temperature of the space A gets to such a low point that the thermostat 31 is operated to withdraw the bridge 58 from the contacts 39 and 48 the system will resume as before.
The method of heating hereinbeiore described is applicable to any situation where a space must be heated but is particularly applicable to the heating of vehicles propelled by electricity because in such case the electrical energy is available as it may be taken from the same source as that which propels the vehicles.
Although I have particularly described several particular physical embodiments of my invention and explained the operation, construction and principle thereof, nevertheless, I desire to have it understood that the forms selected are merely illustrative, but do not exhaust the pos sible physical embodiments of the idea of means underlying my invention.
What I claim as new and desire to secure by Letters Patent of the United States, is:
1. In a heating system, in combination: a heating unit; a selectively operable second heating unit; a motor; means operated by the motor for causing a flow of air over both of the heating units; means for suppiying electrical energy to the motor including a resistance in series therewith; a circuit closing and opening device and means operable exclusively by said motor to open and close said device; means for causing a flow or" electricity through the first of said heating units including the said circuit closing and opening device; means for causing a flow of electricity through the second mentioned heating unit controlled by the last mentioned means; and means for causing a flow of electricity through said motor through less than all of the said resistance when said second heating unit is in operation whereby the motor operates at increased speed and causes a greater flow of air over said heating units.
2. In a heating system, in combination: an
electrical heating unit; a fan rotatable relative to said unit for causing movement of air over said heating unit; means for operating said fan; and means operable exclusively by said fan-opcrating means and only while said fan is operating for causing a flow of electrical energy through the said heating unit; a space to be heated; a thermostat in said space; and means controlled by the thermostat for governing the operation of the fan and so the flow of electricity through the heating unit.
3. In a heating system, in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means.
4. In a heating system, in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of an other electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted to close said control circuit when said blower means is operated, and to open said control circuit when said blower means is inoperative, whereby the portion of said heating circuit controlled thereby is energized when said blower means operates, and is deenergized when said blower means is inoperative,
5. In a heating system, in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermo static device adapted to establish and break saidshunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of another electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted to close said control circuit when said blower means is operated, and to open said control circuit when said blower means is inoperative, whereby the portion of said heating circuit controlled thereby is energized when said blower means operates, and is de-energized when said blower means is inoperative; and further characterized by having said blower-energizing circuit, said heater-energizing circuit and said control circuit disposed respectively in branches of a circuit under the control of said first-named electro-magnetic relay, and brought into operation successively thereto in the order named.
6. In a heating system, in combination: a space to be heated; an electrically energizable means for heating said space; an electrically energizable means for blowing air over said heating means in transit to said space; a source of electrical potential, including an electrical main; a power circuit connected with said main and including said blower means; a shunt adapted to govern the operation of said power circuit, and a thermostatic device adapted to establish and break said shunt in response to changes in temperature in the air influenced by said heating means; a heating circuit including at least a portion of said space heating means, and an electro-magnetic relay associated with said thermostatic device and adapted to serve therewith in governing the operation of said blower means; and a control circuit for said heating circuit, said control circuit including a relay coil of another electro-magnetic relay adapted to establish and break said heating circuit, said control circuit having a gap adapted to be bridged by a bridging member, and said blower means having a bridging member adapted "to close said control circuit when said blower means is operated, and to open said control circuit when said blower means is inoperative, whereby the portion of said heating circuit controlled thereby is energized when said blower means operates, and is de-energized when said blower means is inoperative; and further characterized by having the electrical energy for said heating circuit derived from said main by a branch thereof separately from said blower-operating circuit, whereby the heating current supply is by-passed relatively to said first-named electrical relay, while the operation of said controlcircuit, and consequently, of said heating circuit remains under the control of said blower actuating means.
ROBERT J. PARSONS.
US740113A 1934-08-16 1934-08-16 Heater Expired - Lifetime US2075463A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US740113A US2075463A (en) 1934-08-16 1934-08-16 Heater

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US740113A US2075463A (en) 1934-08-16 1934-08-16 Heater

Publications (1)

Publication Number Publication Date
US2075463A true US2075463A (en) 1937-03-30

Family

ID=24975098

Family Applications (1)

Application Number Title Priority Date Filing Date
US740113A Expired - Lifetime US2075463A (en) 1934-08-16 1934-08-16 Heater

Country Status (1)

Country Link
US (1) US2075463A (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984728A (en) * 1958-05-21 1961-05-16 Maxwell K Murphy Radiant heater
US3412232A (en) * 1963-12-31 1968-11-19 Westinghouse Electric Corp Railway car heating and ventilating systems
WO2023091989A1 (en) * 2021-11-17 2023-05-25 Tutco, Llc Gas heater

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2984728A (en) * 1958-05-21 1961-05-16 Maxwell K Murphy Radiant heater
US3412232A (en) * 1963-12-31 1968-11-19 Westinghouse Electric Corp Railway car heating and ventilating systems
WO2023091989A1 (en) * 2021-11-17 2023-05-25 Tutco, Llc Gas heater

Similar Documents

Publication Publication Date Title
US3327197A (en) Motor starting device including a surge limiter and cutout means
US2075463A (en) Heater
US2032658A (en) Motorized control mechanism
US2656111A (en) Temperature control system
US2262341A (en) System for controlling the flow of heating mediums
US1996972A (en) Heating and ventilating system
US2287045A (en) Control apparatus
US2568700A (en) Multiple step line switch load limiting relay
US2623699A (en) Relay operated temperature responsive control system
US1975130A (en) Control for heating systems
US2196005A (en) Electric heating apparatus
US2979596A (en) Windshield temperature controller
US2333066A (en) Control means
US1921204A (en) Voltage compensated starting relay for split phase motors
US3997827A (en) Shaded pole electric motor and brake
US2365709A (en) Condition control
US2610797A (en) Temperature control apparatus
US1149150A (en) System of control.
US2039300A (en) Control for air conditioning systems
US2675511A (en) Motor control apparatus
US2522286A (en) Temperature control apparatus
US2392290A (en) Heating control
US2166316A (en) Railway traffic controlling apparatus
US2040951A (en) Motor resistance heater
US2386569A (en) Air conditioning