Control and diagnostic method for a differential system
Methods and systems for a differential assembly are provided herein. In one example, a method is provided that includes operating a clutch motor coupled to a differential locking clutch to place the differential locking clutch in a locked configuration. The method further includes, after the differential locking clutch is placed in the locked configuration, reducing electric power delivered to the clutch motor at a first rate and increasing the electric power delivered to the clutch motor when it is determined that clutch disengagement is occurring based on outputs from a motor position sensor or outputs from shaft speed sensors coupled to a pair of shafts coupled to the differential locking clutch.
1. A method for an actuation assembly of a differential locking clutch, comprising:
capturing a first position value of a clutch motor and a second position value of the clutch motor when the differential locking clutch reaches a kiss point and a fully engaged point, respectively; and
triggering a first fault indicator in response to a variance between the first position value and the second position value surpassing a first threshold value, wherein the first fault indicator is indicative of degradation of the differential locking clutch.
2. The method of claim 1 , further comprising triggering a second fault indicator based on a speed of the clutch motor during locking clutch engagement.
3. The method of claim 2 , wherein the speed of the clutch motor is determined based on an average speed of a segment that is bounded by the kiss point and the fully engaged point.
4. The method of claim 3 , wherein the triggering the second fault indicator based on the speed of the clutch motor including triggering the second fault indicator in response to a derivative of the speed of the clutch motor is less than a second threshold value.
5. The method of claim 2 , wherein the speed of the clutch motor is determined based on the first position value and the second position value.
6. The method of claim 2 , wherein the speed of the clutch motor is determined based on a plurality of position values of the clutch motor different from the first position value and the second position value.
7. The method of claim 1 , wherein the first threshold value is a predetermined value.
8. The method of claim 1 , wherein the first fault indicator includes a fault flag.
9. The method of claim 8 , wherein the first fault indicator includes one or more of a visual indicator, an audio indicator, and a haptic indicator.
10. A vehicle driveline system, comprising:
a differential locking clutch configured to selectively inhibit speed differentiation between a first drive axle and a second drive axle;
an actuation assembly including a clutch motor that is rotationally coupled to an actuator, wherein the actuator is configured to engage and disengage the differential locking clutch; and
a controller including instructions stored in non-transitory memory that when executed, in response to a variance between a first motor position value and a second motor position value surpassing a threshold value, cause the controller to:
trigger a first fault indicator.
11. The vehicle driveline system of claim 10 , wherein the first fault indicator is indicative of degradation of the differential locking clutch.
12. The vehicle driveline system of claim 10 , wherein the controller further includes instructions stored in the non-transitory memory that when executed cause the controller to:
determine a speed of the clutch motor based on a plurality of sequential motor positions generated by a motor position sensor; and
trigger a second fault indicator based on the speed of the clutch motor during locking clutch engagement, wherein the second fault indicator is indicative of degradation of the actuation assembly.
13. The vehicle driveline system of claim 12 , wherein the actuator includes a ball ramp actuator.
14. The vehicle driveline system of claim 10 , wherein the differential locking clutch is an interaxle differential (IAD) locking clutch in an IAD.
15. The vehicle driveline system of claim 14 , wherein the IAD is rotationally coupled to a first drive axle and a second drive axle.
16. A method for a differential, comprising:
triggering a first fault indicator in response to a variance between a first position value of a clutch motor and a second position value of the clutch motor surpassing a threshold value, wherein the clutch motor is included in an actuation assembly and coupled to a locking clutch and the first fault indicator is indicative of degradation of the locking clutch; and
triggering a second fault indicator based on a speed of the clutch motor during locking clutch engagement, wherein the second fault indicator is indicative of locking assembly degradation.
17. The method of claim 16 , wherein the differential is an interaxle differential (IAD).
18. The method of claim 16 , wherein the first fault indicator and the second fault indicator each include one or more of a visual indicator, an audio indicator, and a haptic indicator.
19. The method of claim 16 , wherein the speed of the clutch motor is determined based on an average speed of the clutch motor during clutch engagement.
20. The method of claim 19 , wherein the clutch engagement is bounded by a kiss point and a full engagement point.