Method & apparatus for managing alternator loads on engines

• US 5,038,728 A
• Filed: 01/24/1990
• Issued: 08/13/1991
• Est. Priority Date: 05/25/1988
• Status: Expired due to Fees

• Current Assignee: Louis T. Yoshida
• Original Assignee: Nutronics Corporation
• Inventors: Poland, Robert L., Forbis, James M., Yoshida, Louis T.
• Primary Examiner(s): Nelli, Raymond A.
• Application Number:
  US07/470,432
• Time in Patent Office: 566 Days
• Field of Search: 123/339, 123/198 R, 123/198 D, 310/102 R, 310/113, 310/273, 320/72, 171/313, 180/65, 364/431.03
• US Class Current: 123/198.00R
• CPC Class Codes: F02D 2041/2048 said control involving a limitation, e.g. applying current or voltage limits
• CPC Class Codes: F02D 2200/503 Battery correction, i.e. corrections as a function of the state of the battery, its output or its type
• CPC Class Codes: F02D 2250/18 Control of the engine output torque
• CPC Class Codes: F02D 29/06 peculiar to engines driving electric generators
• CPC Class Codes: F02D 41/083 taking into account engine load variation, e.g. air-conditionning
• CPC Class Codes: F02D 41/3005 Details not otherwise provided for
• CPC Class Codes: H02J 7/2434 with pulse modulation

Abstract

The improved engine load management system of the present invention includes an apparatus that will de-excite the field coils of an alternator that is driven by an internal combustion engine when the battery that the alternator charges is above a required minimum voltage and when the engine is operating under high load conditions such as acceleration or climbing. When the battery charge falls below the required minimum, the apparatus excites the alternator field coils and permits the alternator to charge the battery despite a high engine load condition. When the battery charge is above the minimum required voltage, but below the voltage at which charging is discontinued, and the engine is under high load, the alternator field coils are energized and de-energized in a cycle that reduces alternator drag on the engine, but permits limited battery charging to occur. The limited charging rate is greater as the battery voltage is lower, and the change from lesser battery charging to greater battery charging is linear and inversely related to the charge of the battery. When the engine is operating at normal load conditions, such as cruise, battery charging is accomplished on demand under normal circumstances. Deferring battery charging by limiting alternator field coil excitation, reducing alternator drag on the engine during heavy load conditions (an inherently inefficient operating regime for internal combustion engines) increases fuel economy and decreases atmospheric pollutants from automobiles equipped with the apparatus of the current invention.

Claims

1. The method of managing loads on an engine equipped with an alternator-type battery charging system that includes a voltage regulator adapted to shut down the alternator electrical generation functions by turning off electrical current to the alternator field windings when a threshold battery voltage level is reached comprising the steps of:

sensing the load condition of the engine;

causing the alternator to decrease or shut down its electrical generation when the engine is under a heavy load, even though the battery is not charged to the threshold level normally set for the voltage regulator to decrease or shut down the alternator electrical generation; and

establishing an alternative minimum battery voltage threshold, below which it is undesirable to allow the battery to discharge, sensing the voltage level of the battery, and re-exciting the alternator field circuit when the battery discharges to or below said alternative minimum battery voltage threshold, even when the engine is still under heavy load.

2. The method of claim 1, including the steps of establishing a proportional charging range between said alternative minimum battery voltage threshold and an alternator disabling threshold battery voltage level, said alternator disabling threshold being a battery voltage level that is more than said alternate minimum battery voltage level and less than said normal threshold level, and proportionally disabling the field when the battery voltage level is within said proportional charging range in such a manner that the alternator electrical generation increases as the battery voltage level decreases toward said alternate minimum battery voltage threshold and decreases as the battery voltage increases toward alternator disabling threshold.

3. The method of claim 2, including the steps of disabling the field by switching the field excitation current on and off for varying durations.

4. The method of claim 3, including the steps of switching the field excitation circuit continuously "off" when the engine is under heavy load and the battery voltage level is above said alternator disabling threshold, pulsing said field excitation circuit on and off when the battery voltage is in said proportional charging range in such a manner that the duration of the "on" pulses increase and the duration of the "off" pulses decrease as the battery voltage discharges toward said alternate minimum battery voltage level, and switching said field excitation circuit essentially continuously "on" when the battery voltage level discharges below said alternate minimum battery voltage.

5. The method of claim 4, including the steps of generating switching signals for switching the field circuit on and off by generating an oscillating wave form, comparing the oscillating wave form voltage to a voltage representative of the battery voltage level, and generating an "off" signal whenever the battery representative voltage is greater than the oscillating wave form voltage and generating an "on" signal whenever the battery representative voltage is less than the oscillating wave form voltage.

6. The method of claim 5, including the steps of biasing said oscillating wave form with a bias voltage equal to said representative battery voltage when the battery voltage level is at the midpoint of said proportional charging range.

7. The method of claim 6, including the steps of generating said oscillating wave form with an amplitude such that the maximum wave form voltage is equal to the representative battery voltage when the battery voltage level is at said alternator disabling threshold and the minimum wave form voltage is equal to the representative battery voltage when the battery voltage level is at said alternate minimum battery voltage threshold.

8. The method of claim 7, including the steps of generating said bias voltage to remain at a constant predetermined level, and generating said oscillating wave form with a constant predetermined amplitude.

9. The method of claim 8, including the step of generating said oscillating wave form in a triangular wave form configuration.

10. The method of claim 9, including the step of providing said battery representative voltage at a constant fraction of the actual battery voltage such that the said battery representative voltage is less than, but varies in direct proportion to, the actual battery voltage, and providing a light load swamp circuit for swamping said bias voltage with actual battery voltage when the engine is not heavily loaded, thus driving said oscillating wave form above said battery representative voltage and causing the field excitation circuit to be switched constantly "on".

11. The method of claim 10, including the step of sensing the engine load condition by sensing engine manifold vacuum, and actuating said swamp circuit when the manifold vacuum is high and deactuating said swamp circuit when the manifold vacuum is low.

12. The method of managing loads on an engine equipped with an alternator-type battery charging system that includes a voltage regulator adapted to shut down the alternator electrical generation functions by turning off electrical current to the alternator field windings when a threshold battery voltage level is reached, comprising the steps of:

sensing the load condition of the engine;

causing the alternator to decrease or shut down its electrical generation when the engine is under a heavy load, even though the battery is not charged to the threshold level normally set for the voltage regulator to decrease or shut down the alternator electrical generation;

producing a boosted apparent voltage that is higher than the actual battery voltage, and feeding said boosted apparent voltage to the voltage regulator instead of the actual battery voltage when the engine is heavily loaded to induce the voltage regulator to decrease electrical generation by the alternator when the voltage regulator would normally allow more electrical generation by the alternator.

13. The method of claim 12, including the step of determining an alternator disabling threshold at a voltage level less than the normal threshold level, and boosting the actual battery voltage by a boost voltage amount equal to the difference between the alternator disabling threshold and the normal threshold level.

14. The method of claim 13, including the steps of boosting the actual battery voltage by generating a pulsed square wave, amplifying the pulsed square wave and driving a center-tapped step-down transformer, biasing the secondary windings of the transformer with the battery voltage level to create two half-cycle square waves having a peak voltage higher than the actual battery voltage, and rectifying and combining the two half-cycle square waves to produce the boosted apparent voltage.

15. The method of claim 14, including the steps of controlling the boost voltage to maintain it equal to the difference between the alternator disabling threshold and the normal threshold level by producing a reference voltage that varies in direct proportion to the actual battery voltage, producing a monitor voltage that also varies as a function of battery voltage, but which is equal to the reference voltage when the boost voltage is at the desired magnitude, comparing the reference voltage and the boost voltage, and using any difference between the reference voltage and the boost voltage to adjust the pulse width of the square wave in such a manner as to bring the monitor voltage into balance with the reference voltage.

16. The method of claim 15, including the steps of turning "on" the square wave generator when the engine is loaded and turning "off" the square wave generator when the engine is not loaded.

17. The method of claim 16, including the steps of sensing the engine manifold vacuum and turning "on" the square wave generator when the manifold vacuum is low and turning off the square wave generator when the manifold vacuum is high.

18. Engine load management apparatus for disabling and enabling an alternator charging system in response to engine loading and unloading in a vehicle that has an engine-powered alternator with field windings, a battery, and a voltage regulator for limiting or shutting down the generation of electricity by the alternator when the battery voltage reaches a predetermined normal maximum charge level, comprising:

engine load sensor means for sensing load condition of the engine;

alternator disabling means connected to said engine load sensor means; and

said alternator disabling means including a variable switch signal generator means for generating switching signals to open and close said field windings in response to engine load conditions.

19. The apparatus of claim 18, wherein said switch signal generator means includes battery voltage sensor means for sensing the actual battery voltage, said switch signal generator means being constructed to generate a switch signal that continuously opens said field circuit when the engine is loaded and the battery voltage is higher than a predetermined alternator disabling threshold, which alternator disabling threshold is lower than said normal maximum charge level.

20. The apparatus of claim 19, wherein said switch signal generator means is also constructed to generate a switch signal that continuously closes said field circuit when the battery voltage is lower than a predetermined alternative minimum voltage threshold, regardless of engine load condition.

21. The apparatus of claim 20, wherein said switch signal generator means is also constructed to generate a pulsed switch signal that causes said field circuit switch means to cycle back and forth between opened and closed modes when the engine is loaded and the battery voltage is between said predetermined alternator disabling threshold and said alternative minimum voltage threshold.

22. The apparatus of claim 21, wherein said switch signal generator means is also constructed to generate a pulsed switch signal that causes the duration of pulses that open the field circuit to be longer when the battery voltage is near said alternator disabling threshold and to decrease in duration as the battery voltage discharges toward said alternative minimum voltage threshold.

23. The apparatus of claim 22, wherein said switch signal generator includes waveform generation means for producing an oscillating waveform, representative sample voltage means for producing a voltage that is representative of the actual battery voltage, and comparator means for comparing the representative battery voltage to the waveform form voltage and producing an "open" field circuit switch signal whenever the representative battery voltage is greater than the waveform voltage and for producing a "close" field circuit switch signal whenever the representative battery voltage is less than the waveform voltage.

24. The apparatus of claim 23, wherein said switch signal generator includes precision voltage reference means for producing a constant precision voltage reference, said oscillating waveform being biased by said precision voltage reference, and said representative sample voltage being equal to said precision voltage reference when the battery voltage is at the midpoint of the range between said alternator disabling threshold and said alternative minimum voltage threshold.

25. The apparatus of claim 24, wherein said waveform generation means generates said oscillating waveform with an amplitude such that the maximum voltage of the biased waveform is equal to the representative battery voltage when the actual battery voltage is equal to said alternator disabling threshold and the minimum voltage of the biased waveform is equal to the representative battery voltage when the actual battery voltage is equal to said alternative minimum threshold.

26. The apparatus of claim 25, wherein said representative battery voltage is a constant fraction of the actual battery voltage.

27. The apparatus of claim 26, wherein said engine load sensor means includes load sensitive switch means for sensing when the engine is not loaded and applying battery voltage to swamp said precision reference voltage-biased waveform to cause said switch signal generator means to generate a constant "closed" mode signal for said field circuit switch means.

28. The apparatus of claim 27, wherein said load sensitive switch means includes a vacuum switch connected to the manifold vacuum of the engine and configured to connect the battery voltage to said oscillating waveform when the manifold vacuum is high.

29. Engine load management apparatus for disabling and enabling an alternator charging system in response to engine loading and unloading in a vehicle that has an engine-powered alternator with field windings, a battery, and a voltage regulator for limiting or shutting down the generation of electricity by the alternator when the battery voltage reaches a predetermined normal maximum charge level, comprising:

engine load sensor means for sensing load condition of the engine;

alternator disabling means connected to said engine load sensor means; and

said alternator disabling means includes boost voltage generator means for producing a boosted apparent voltage that is higher than the actual voltage for inducing the voltage regulator to decrease electrical generation by the alternator when there is a load on the engine and the actual battery voltage is less than the normal maximum charge level.

30. The apparatus of claim 29, wherein said boost voltage generator means is constructed to boost the actual battery voltage by a predetermined incremental boost voltage.

31. The apparatus of claim 30, wherein said alternator disabling means includes square wave generator means for producing a pulsed square wave, and wherein said boost voltage generator means includes amplifier means for amplifying said pulsed square wave, step down center-tapped transformer means for producing two half-cycle square waves biased by the actual battery voltage and rectifier means for rectifying and joining said two half-cycle biased square waves together to produce said boosted apparent voltage.

32. The apparatus of claim 31, including boost voltage level control means for maintaining the boost voltage at a predetermined amount to produce a boosted apparent voltage at the predetermined incremental level above the actual battery voltage.

33. The apparatus of claim 32, wherein said boost level voltage control means includes precision voltage reference means for producing a voltage that varies in direct proportion to the actual battery voltage, boost voltage monitor means tapped into the boosted apparent voltage for producing a divided down monitor voltage that is a constant fraction of the boosted apparent voltage and which is equal to said precision voltage reference when the boosted apparent voltage is at the desired incremental boost voltage amount above the actual battery voltage, and comparator means for comparing said precision voltage reference with said monitor voltage and using any difference to adjust the square wave generator to change the square wave in such a manner as to bring the monitor voltage into balance with the precision voltage reference.

34. The apparatus of claim 33, wherein said engine load sensor means includes load-sensitive switch means connected to said square wave generator means for actuating said square wave generator to produce said pulsed square wave when the engine is loaded.

35. The apparatus of claim 34, wherein said loadsensitive switch means includes a vacuum switch connected to the manifold vacuum of the engine and configured to actuate said square wave generator when the manifold vacuum is low and to deactuate said square wave generator when the manifold vacuum is high.