US3568016A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Variable speed motor ventilation system
Assignee: Caterpillar Global Mining LLC
•
Filing: 1968-10-14
•
Granted: 1971-03-02
•
Expires: 1988-10-14
Abstract
Abstract A ventilating system for an alternating current wound rotor induction motor having resistors in the secondary circuit of the rotor, in which a cooling fan driven by an auxiliary motor is provided for circulating air through the induction motor. The auxiliary fan motor is energized through connections with the resistors in the rotor secondary circuit, and the speed of the fan motor is dependent upon the frequency or voltage appearing at the connections with the resistors, whereby fan motor speed will increase whenever the wound rotor induction motor speed decreases to ensure an adequate flow of cooling air.
Inventors
- 👤 Donald E Barber
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 17:42
CPC Classifications
H; H02; H02K; H02K9/00; H02K9/02; H02K9/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
159 words
In a Cooling system for a variable speed alternating current motor having rotor and stator elements, the combination comprising: two sets of windings for one of said elements that are shiftable relative to one another to induce voltages in the other said element that are phase displaceable to vary motor speed steplessly; a secondary circuit for said other element with connections to derive a voltage therefrom that varies in frequency inversely with rotor element speed; a first cooling fan that turns with said rotor element to deliver cooling air to the motor in an amount proportional to rotor element speed; a second cooling fan in air circulating relation with said motor; and a fan motor driving said second cooling fan which is electrically joined with said secondary connections to be operated therefrom at a speed inversely proportional to said rotor element speed for supplying cooling air in an amount varying inversely with that delivered by said first cooling fan.
Claim 2
Dependent Claim
159 words
In a Cooling system for a variable speed alternating current motor having rotor and stator elements, the combination comprising: two sets of windings for one of said elements that are shiftable relative to one another to induce voltages in the other said element that are phase displaceable to vary motor speed steplessly; a secondary circuit for said other element with connections to derive a voltage therefrom that varies in frequency inversely with rotor element speed; a first cooling fan that turns with said rotor element to deliver cooling air to the motor in an amount proportional to rotor element speed; a second cooling fan in air circulating relation with said motor; and a fan motor driving said second cooling fan which is electrically joined with said secondary connections to be operated therefrom at a speed inversely proportional to said rotor element speed for supplying cooling air in an amount varying inversely with that delivered by said first cooling fan.
Claim 3
Dependent Claim
28 words
A cooling system as in claim 1 having a rectifier between said secondary connections and said second cooling fan, the second cooling fan being a direct current motor.
Claim 4
Dependent Claim
143 words
In a cooling system for a variable speed alternating current motor having rotor and stator elements, the combination comprising: a circuit for one of said elements having secondary resistance that shapes the motor speed-torque curve and provides variable speed for the motor; connections for said circuit to derive a voltage therefrom that varies in frequency inversely with rotor element speed; a first cooling fan that turns with said rotor element to deliver cooling air to the motor in an amount proportional to rotor element speed; a second cooling fan in air circulating relation with said motor; and a fan motor driving said second cooling fan which is electrically joined with said connections to be operated therefrom at a speed inversely proportional to said rotor element speed for supplying cooling air in an amount varying inversely with that delivered by said first cooling fan.
Claim 5
Dependent Claim
143 words
In a cooling system for a variable speed alternating current motor having rotor and stator elements, the combination comprising: a circuit for one of said elements having secondary resistance that shapes the motor speed-torque curve and provides variable speed for the motor; connections for said circuit to derive a voltage therefrom that varies in frequency inversely with rotor element speed; a first cooling fan that turns with said rotor element to deliver cooling air to the motor in an amount proportional to rotor element speed; a second cooling fan in air circulating relation with said motor; and a fan motor driving said second cooling fan which is electrically joined with said connections to be operated therefrom at a speed inversely proportional to said rotor element speed for supplying cooling air in an amount varying inversely with that delivered by said first cooling fan.
Claim 6
Dependent Claim
27 words
A cooling system as in claim 3 having a rectifier between said connections and said second cooling fan, the second cooling fan being a direct current motor.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-01 | 1974-08-31 | 1975-03-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-01 | 1978-08-31 | 1979-03-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-01 | 1982-08-31 | 1983-03-02 | $7700.00 | Window Closed / Lapsed |