Vehicle alternator

• US 20020000791A1
• Filed: 06/29/2001
• Published: 01/03/2002
• Est. Priority Date: 06/29/2000
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Tanaka, Koji, Okuno, Tomoya, Taniguchi, Makoto
• Granted Patent: US 6,456,048 B2
• Time in Patent Office: Days
• 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 having a rotor including a plurality of field poles and driven by a vehicle engine, a field coil for magnetizing said field poles, an armature including an armature coil and arranged facing said field poles of said rotor;

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 rotor; 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 region to a low rotation speed side based on the electricity amount related to rotation speed, and

within the rotation speed region, 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 region to the low rotation speed side 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 step-wisely 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.

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 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.