Apparatus for estimating clutch temperature

• US 6,769,526 B2
• Filed: 12/18/2002
• Issued: 08/03/2004
• Est. Priority Date: 09/19/2000
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fukuda, Yoshiyuki, Murata, Shigeo, Iida, Norio, Gotou, Atsuhiko, Mizuya, Satoshi, Kusukawa, Hirotaka
• Primary Examiner(s): Lorence, Richard M.
• Application Number:
  US10/311,595
• Publication Number:
  US 20030150685A1
• Time in Patent Office: 594 Days
• Field of Search: 192/82.T, 477/76, 477/98
• US Class Current: 192/82.00T
• CPC Class Codes: B60K 23/0808 for varying torque distribution between driven axles, e.g. by transfer clutch
• CPC Class Codes: B60W 10/119 including control of all-wheel-driveline means, e.g. transfer gears or clutches for dividing torque between front and rear axle B60W10/14 takes precedence
• CPC Class Codes: B60W 2510/0291 Clutch temperature
• CPC Class Codes: B60W 30/186 excessive wear or burn out of friction elements, e.g. clutches
• CPC Class Codes: F16D 2500/1025 with threaded transmission
• CPC Class Codes: F16D 2500/10431 4WD Clutch dividing power between the front and the rear axle
• CPC Class Codes: F16D 2500/30405 Estimated clutch temperature
• CPC Class Codes: F16D 2500/30406 Clutch slip
• CPC Class Codes: F16D 2500/3115 Vehicle wheel speed
• CPC Class Codes: F16D 2500/5102 Detecting abnormal operation, e.g. unwanted slip or excessive temperature
• CPC Class Codes: F16D 2500/5106 Overheat protection
• CPC Class Codes: F16D 2500/70424 Outputting a clutch engaged-disengaged signal
• CPC Class Codes: F16D 2500/70678 using histograms
• CPC Class Codes: F16D 27/004 with permanent magnets combined with electromagnets
• CPC Class Codes: F16D 27/115 with more than two discs, e.g. multiple lamellae
• CPC Class Codes: F16D 28/00 Electrically-actuated clutches arrangements for synchronisation F16D23/02; clutches actuated directly by means of an electromagnet F16D27/00; automatic clutches F16D43/00 - F16D45/00; external control F16D48/00
• CPC Class Codes: F16D 48/06 Control by electric or electronic means, e.g. of fluid pressure

Abstract

The present invention provides an apparatus for estimating clutch temperature estimates clutch temperatures that closely follow actual clutch temperature without a temperature sensor and at low cost. The apparatus employs method for calculating energy applied to the driving clutch according to the detected rotational speed difference and estimated torque and method for estimating a clutch temperature variation based on the calculated energy and estimating a clutch temperature based on the estimated clutch temperature variation.

Claims

1. An apparatus for estimating the temperature of a driving clutch whose engagement including slide engagement is controllable, comprising:

a clutch speed difference detector detecting a rotational speed difference between input and output shafts of the driving clutch;

a torque estimator estimating torque transmitted through the driving clutch;

an energy calculator calculating energy applied to the driving clutch according to the detected rotational speed difference and estimated torque;

a temperature estimator estimating a clutch temperature variation based on the calculated energy and estimating a clutch temperature based on the estimated clutch temperature variation; and

a determination unit determining whether or not the calculated energy is equal to or above a reference energy level, wherein

if the calculated energy is determined to be equal to or above the reference energy level, the temperature estimator increases the estimated clutch temperature by an increment, and if the calculated energy is determined to be below the reference energy level, the temperature estimator decreases the estimated clutch temperature by a decrement.

2. The apparatus of claim 1, wherein

the reference energy level corresponds to an energy level at which the driving clutch substantially maintains a constant temperature.

3. The apparatus of claim 1, wherein

the increment is set in proportion to a difference between the calculated energy and the reference energy level, and the decrement is set to a predetermined value.

4. The apparatus of claim 1, further comprising:

a temperature gradient setter setting a temperature incremental gradient gentler than an actual temperature incremental gradient and a temperature decremental gradient steeper than an actual temperature decremental gradient if the estimated clutch temperature is within a practical driving temperature domain, and a temperature incremental gradient steeper than an actual temperature incremental gradient and a temperature decremental gradient gentler than an actual temperature decremental gradient if the estimated clutch temperature is in a high-load temperature domain, the set temperature incremental gradient being used to determine the increment, the set temperature decremental gradient being used to determine the decrement.

5. The apparatus of claim 1, further comprising:

a vehicle speed detector detecting a vehicle speed; and

an estimation terminator, wherein;

if the detected vehicle speed is equal to or above a reference speed, the estimation terminator terminates the temperature estimator estimating a clutch temperature and restores an initial state.

6. The apparatus of claim 1, further comprising

a clutch controller, wherein:

the driving clutch is arranged to distribute engine torque among front and rear wheels and the estimated clutch temperature is used as data to start protective clutch control to prevent the overheating of the driving clutch; and

the clutch controller operates to decrease the temperature of the driving clutch if the estimated clutch temperature is equal to or above a clutch protection temperature.

7. The apparatus of claim 6, wherein:

the clutch controller sets a clutch limit temperature higher than the clutch protection temperature; and

the clutch controller enhances the engagement of the driving clutch if the estimated clutch temperature is equal to or above the clutch protection temperature and disengages the driving clutch if the estimated clutch temperature is equal to or above the clutch limit temperature.

8. The apparatus of claim 7, wherein:

normal clutch control is carried out until the estimated clutch temperature reaches the clutch protection temperature and a normal control temperature lower than the clutch protection temperature is set for the normal clutch control; and

the apparatus further comprises a normal clutch control resumption mechanism, the apparatus enhancing the engagement of the driving clutch if the estimated clutch temperature is equal to or above the clutch protection temperature, disengaging the driving clutch if the estimated clutch temperature is equal to or above the clutch limit temperature, and switching the protective clutch control to the normal clutch control if the estimated clutch temperature is equal to or below the normal control temperature.

9. The apparatus of claim 8, wherein:

the clutch speed difference detector detects the rotational speed difference between the input and output shafts of the driving clutch according to a difference between an average of front wheel speeds provided by left and right wheel speed sensors and an average of rear wheel speeds provided by left and right rear wheel speed sensors; and

the energy calculator compares the detected rotational speed difference with a minimum difference set according to a detection limit of the wheel speed sensors, calculates energy applied to the driving clutch according to the detected rotational speed difference if the detected rotational speed difference is above the minimum difference, and calculates energy applied to the driving clutch by zeroing the detected rotational speed difference if the detected rotational speed difference is equal to or below the minimum difference.

10. An apparatus for estimating the temperature of a driving clutch whose engagement including slide engagement is controllable, comprising:

clutch speed difference detecting means for detecting a rotational speed difference between input and output shafts of the driving clutch;

torque estimating means for estimating torque transmitted through the driving clutch;

energy calculating means for calculating energy applied to the driving clutch according to the detected rotational speed difference and estimated torque;

temperature estimating means for estimating a clutch temperature variation based on the calculated energy and estimating a clutch temperature based on the estimated clutch temperature variation; and

determining means for determining whether or not the calculated energy is equal to or above a reference energy level, wherein

if the calculated energy is determined to be equal to or above the reference energy level, the temperature estimating means increases the estimated clutch temperature by an increment, and if the calculated energy is determined to be below the reference energy level, the temperature estimating means decreases the estimated clutch temperature by a decrement.

11. A method of estimating the temperature of a driving clutch whose engagement including slide engagement is controllable, comprising:

detecting a rotational speed difference between input and output shafts of the driving clutch;

estimating torque transmitted through the driving clutch;

calculating energy applied to the driving clutch according to the detected rotational speed difference and estimated torque;

estimating a clutch temperature variation based on the calculated energy and estimating a clutch temperature based on the estimated clutch temperature variation; and

determining whether or not the calculated energy is equal to or above a reference energy level, wherein

if the calculated energy is determined to be equal to or above the reference energy level, the clutch temperature estimating operation increases the estimated clutch temperature by an increment, and if the calculated energy is determined to be below the reference energy level, the clutch temperature estimating operation decreases the estimated clutch temperature by a decrement.

12. The method of claim 11, wherein

the reference energy level corresponds to an energy level at which the driving clutch substantially maintains a constant temperature.

13. The method of claim 11, wherein

the clutch temperature estimating operation sets a temperature incremental gradient gentler than an actual temperature incremental gradient and a temperature decremental gradient steeper than an actual temperature decremental gradient if the estimated clutch temperature is within a practical driving temperature domain, and a temperature incremental gradient steeper than an actual temperature incremental gradient and a temperature decremental gradient gentler than an actual temperature decremental gradient if the estimated clutch temperature is in a high-load temperature domain, the set temperature incremental gradient being used to determine the increment, the set temperature decremental gradient being used to determine the decrement.