Systems and methods of reducing a load on an engine

• US 8,476,872 B2
• Filed: 08/12/2010
• Issued: 07/02/2013
• Est. Priority Date: 08/12/2009
• Status: Active Grant

• Current Assignee: Thermo King Corporation (Trane Technologies plc)
• Original Assignee: Thermo King Corporation (Trane Technologies plc)
• Inventors: Truckenbrod, Gregory R., Waldschmidt, William L., McFadden, John Steven, Trivedi, Vidhey Vijay
• Primary Examiner(s): Ponomarenko, Nicholas
• Application Number:
  US12/855,222
• Publication Number:
  US 20110037441A1
• Time in Patent Office: 1,055 Days
• Field of Search: 322/22, 322/25, 322/27, 322/28, 322/37
• US Class Current: 322/28
• CPC Class Codes: H02J 7/1438 in combination with power supplies for loads other than batteries
• CPC Class Codes: H02J 7/163 with special means for initiating or limiting the excitation current
• CPC Class Codes: H02P 9/48 Arrangements for obtaining a constant output value at varying speed of the generator, e.g. on vehicle H02P9/04 - H02P9/46 take precedence

Abstract

A system for reducing an alternator'"'"'s load on an engine when the engine drives a second load. The system includes an alternator, a battery, a resistor, and a switch. The alternator includes a stator, a voltage regulator, a rectifier, and a field coil. The battery has a first terminal coupled to the alternator and a second terminal coupled to the alternator. The resistor has a first lead coupled to the first terminal and a second lead coupled to the field coil. The switch is coupled in parallel across the resistor, and is open when the engine drives the second load and closed when the engine is not driving the second load.

Claims

1. A system for reducing an alternator'"'"'s load on an engine when the engine drives a second load, the system comprising:

an alternator including a stator, a voltage regulator, a rectifier, and a field coil;

a battery having a first terminal and a second terminal both of which are coupled to the alternator;

a resistor having a first lead coupled to the first terminal and a second lead coupled to the field coil; and

a switch coupled in parallel across the resistor, the switch being open when the engine drives the second load and closed when the engine is not driving the second load;

wherein the switch receives a signal from the second load indicating when the engine is driving the second load.

2. The system of claim 1, wherein the switch includes a relay, and a coil of the relay receives the signal.

3. The system of claim 2, wherein the coil is coupled between the first terminal and the second load.

4. The system of claim 1, wherein an output of the alternator charges a battery.

5. The system of claim 1, wherein a current passing through the field coil is reduced when the switch is open, wherein the reduction of the current reduces an output of the alternator and reduces the alternator'"'"'s load on the engine.

6. A truck electrical control system, comprising:

an air conditioner driven by an engine and configured to cool a cab of a truck;

an alternator driven by the engine and coupled to the air conditioner, the alternator receiving a signal from the air conditioner indicating whether the air conditioner is operating or not operating, the alternator applying a first load on the engine when the air conditioner is not operating and applying a second load on the engine when the air conditioner is operating, the second load being less than the first load;

a switch, the signal opening the switch to transition the alternator from the first load to the second load; and

a battery charged by the alternator;

wherein the opening of the switch routes current supplied to the field coil through a resistor, wherein the routing of the current through the resistor reduces a field current and reduces an output of the alternator.

7. The truck of claim 6, wherein the difference between the first load and the second load offsets a portion of a load placed on the engine by the air conditioner.

8. The truck of claim 6, wherein the air conditioner includes a clutch, the clutch engaging when the cab requires cooling and disengaging when the cab does not require cooling, and wherein the clutch provides the signal to the alternator.

9. The truck of claim 8, wherein the clutch is engaged when the air conditioner is operating and is disengaged when the air conditioner is not operating.

10. The truck of claim 6, wherein the switch includes a relay and the signal drives a coil of the relay to open a pair of normally-closed contacts.

11. A method of reducing an alternator load on an engine when the engine drives a second load, the method comprising:

driving an alternator by the engine;

applying, by the alternator, a first load on the engine;

connecting a second load to the engine;

providing a signal by the second load in response to the second load connecting with the engine;

receiving the signal by the alternator;

opening a switch by the signal, the switch connected in parallel with a resistor, the switch and resistor coupled between a battery terminal and a field coil of the alternator; and

reducing the first load on the engine when the alternator receives the signal,

wherein the opening of the switch reduces a current supplied to a field coil of the alternator, wherein a resistor reduces a current supplied to the field coil reducing an output of the alternator and reducing the first load.

12. The method of claim 11, further comprising reducing a current supplied to a field coil of the alternator when the alternator receives the signal.

13. The method of claim 11, further comprising driving a coil of a relay by the signal, the coil opening a set of contacts of the relay, wherein the set of contacts is connected in parallel with a resistor, and the set of contacts and the resistor are coupled between a battery terminal and a field coil of the alternator.

14. The method of claim 13, further comprising providing a current to a field coil of the alternator, wherein the field coil is connected in series with the set of contacts and resistor.

15. The method of claim 14, wherein the current is reduced when the set of contacts open, wherein the reduced current reduces an output of the field coil and reduces an output of the alternator.