Vehicle alternator with anti-hunting feature and vehicle alternator control system

• US 6,456,048 B2
• Filed: 06/29/2001
• Issued: 09/24/2002
• Est. Priority Date: 06/29/2000
• Status: Expired due to Fees

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Tanaka, Koji, Okuno, Tomoya, Taniguchi, Makoto
• Primary Examiner(s): Ramirez, Nestor
• Assistant Examiner(s): GONZALEZ, JULIO C
• Application Number:
  US09/893,417
• Publication Number:
  US 20020000791A1
• Time in Patent Office: 452 Days
• Field of Search: 322/28, 322/25, 322/29, 322/59, 322/89
• US Class Current: 322/28
• CPC Class Codes: H02J 7/1446 in response to parameters of a vehicle
• CPC Class Codes: H02P 9/04 Control effected upon non-electric prime mover and dependent upon electric output value of the generator
• CPC Class Codes: Y02T 10/92 Energy efficient charging or discharging systems for batteries, ultracapacitors, supercapacitors or double-layer capacitors specially adapted for vehicles

Abstract

Shift means shifts a rotation speed range to a low rotation speed side based on an electricity amount related to rotation speed. In the rotation speed range, driving torque of a generator is suddenly changes as a result of an increase of duty ratio of a switch due to a shortage of generation capacity caused by a reduction of a rotation speed of a vehicle alternator. Preferably, the shift means shifts the rotation speed range to the low rotation speed side by changing the adjust voltage based on the electricity amount related to rotation speed while the rotation speed is reduced.

Claims

1. An alternator for a vehicle, comprising:

an AC generation section driven by a vehicle engine, and having a field coil and an armature coil;

a rectifying means for rectifying AC voltage generated by said armature coil to DC voltage and charging an electricity accumulating means;

a rotation speed detecting means for detecting an electricity amount related to rotation speed of said AC generation section; and

a voltage control unit including a comparing section for comparing an electricity amount related to the DC voltage with a predetermined adjust voltage and a switch connected in series to said field coil, said voltage control unit converging the DC voltage to the adjust voltage by intermittently controlling said switch based on a compared result of said comparing section, wherein said voltage control unit includes a shift means for shifting a rotation speed of a driving torque inflection point of the alternator based on the electricity amount related to rotation speed so as to reduce the rotation speed of the driving torque inflection point in accordance with a reduction of the rotation speed, and in the driving torque inflection point, driving torque of the alternator suddenly changes as a result of an increase of duty ratio of said switch due to a shortage of generation capacity caused by a reduction of the rotation speed.

2. An alternator according to claim 1, wherein said shift means shifts the rotation speed of the torque inflection point by changing the adjust voltage based on the electricity amount related to rotation speed.

3. An alternator according to claim 2, wherein said shift means changes the adjust voltage in accordance with a change of the electricity amount related to rotation speed.

4. An alternator according to claim 2, wherein

said shift means changes the adjust voltage in accordance with the electricity amount related to rotation speed within a predetermined range of the electricity amount related to rotation speed and within a predetermined range of the adjust voltage,

said shift means sets an upper limit of the adjust voltage corresponding to an upper limit of the electricity amount related to rotation speed, and

said shift means sets a lower limit of the adjust voltage corresponding to a lower limit of the electricity amount related to rotation speed.

5. An alternator according to claim 4, wherein said shift means continuously changes the adjust voltage in accordance with the electricity amount related to rotation speed within the predetermined range of the electricity amount related to rotation speed.

6. An alternator according to claim 5, wherein said shift means changes the adjust voltage in accordance with the electricity amount related to rotation speed within a predetermined control delay time.

7. An alternator according to claim 6, wherein the control delay time is set to 0.1 seconds or less.

8. An alternator according to claim 4, wherein said shift means changes the adjust voltage in a step-like manner in accordance with the electricity amount related to rotation speed within a predetermined range of the electricity amount related to rotation speed.

9. An alternator according to claim 4, wherein the rotation speed corresponding to the upper limit of the electricity amount related to rotation speed is set larger than a rotation speed corresponding to a vehicle engine idling speed.

10. An alternator according to claim 9, wherein the rotation speed corresponding to the upper limit of the electricity amount related to rotation speed is set to 1.5-2 times of a predetermined generation start rotation speed.

11. An alternator according to claim 4, wherein the rotation speed corresponding to the lower limit of the electricity amount related to rotation speed is set larger than a predetermined generation start rotation speed.

12. An alternator according to claim 4, wherein the lower limit of the adjust voltage is approximately equal to an open terminal voltage of said electricity accumulating means or larger than the open terminal voltage by a predetermined voltage.

13. An alternator according to claim 4, wherein the upper limit of the adjust voltage is set to continuous service voltage when the vehicle normally runs.

14. An alternator according to claim 2, wherein said rotation speed detecting means detects the electricity amount related to rotation speed based on a fundamental wave frequency of a one-phase output voltage of said armature coil.

15. An alternator according to claim 14, further including a low-pass filter for extracting a low-pass component of an output voltage of said rotation speed detecting means.

16. An alternator according to claim 1, wherein said rotation speed detecting means converts frequency information included in an output voltage of said armature coil into voltage signal.

17. A vehicle alternator control system for controlling an alternator driven by an engine, comprising:

a field current control section which has a switch connected in series with a field coil of the alternator;

a voltage detecting section which detects an output voltage of the alternator;

a comparing section which compares the detected output voltage and an adjust voltage, and controls the field current control section in response to the comparison result so as to control the detected output voltage to the adjust voltage;

a rotation speed detecting section which detects rotation speed of the alternator; and

a rotation speed responsive section which changes a value of the voltage compared in the comparing section in accordance with the detected rotation speed so as to reduce a rotation speed of an inflection point in accordance with a reduction of the detected rotation speed, in which driving torque of the alternator suddenly changes under a control of the comparing section.

18. The vehicle alternator control system in claim 17, wherein the rotation speed responsive section changes the voltage when the rotation speed is in a range that is defined with a lower limit and an upper limit and substantially corresponds to an idling range of the engine, and the rotation speed responsive section changes the voltage so that the rotation speed of the inflection point is positioned below the detected rotation speed while the rotation speed is in the range.

19. The vehicle alternator control system in claim 17, wherein the rotation speed responsive section changes the adjust voltage.

20. A vehicle alternator control system for controlling an alternator driven by an engine, comprising:

a field current control section which has a switch connected in series with a field coil of the alternator;

a voltage detecting section which detects an output voltage of the alternator;

a control section which controls the field current control section so as to control the detected output voltage to an adjust voltage, the control section providing a driving torque characteristic of the alternator with respect to the rotation speed, the driving torque characteristic having an inflection point in which the driving torque takes a peak value;

a rotation speed detecting section which detects rotation speed of the alternator; and

an adjust voltage setting section which sets the adjust voltage in accordance with the detected rotation speed so as to keep the rotation speed of the inflection point below the detected rotation speed when the rotation speed is in an idling speed range.