Method and apparatus

• US 6,199,450 B1
• Filed: 12/17/1999
• Issued: 03/13/2001
• Est. Priority Date: 12/17/1999
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated
• Original Assignee: Caterpillar Incorporated
• Inventors: Hussain, Danish A., Carlson, Douglas A., Stahl, Alan L.
• Primary Examiner(s): Wright, Dirk
• Application Number:
  US09/466,526
• Time in Patent Office: 452 Days
• Field of Search: 747/331, 477/61
• US Class Current: 74/733.1
• CPC Class Codes: F16H 2059/467 of torque converter
• CPC Class Codes: F16H 47/02 the fluid gearing being of the volumetric type
• CPC Class Codes: F16H 59/14 Inputs being a function of torque or torque demand
• CPC Class Codes: F16H 59/42 Input shaft speed
• CPC Class Codes: F16H 61/0246 characterised by initiating reverse gearshift
• CPC Class Codes: F16H 61/061 using electric control means
• CPC Class Codes: Y10T 74/19163 with interrelated controls

Abstract

A drive line assembly for a work machine is disclosed. The drive line assembly includes an engine driving an engine output shaft and an engine speed sensor which generates engine speed signals indicative of a speed of the engine output shaft. The drive line assembly further includes a torque converter driven by the output shaft which drives a transmission input shaft and a transmission speed sensor which generates transmission speed signals indicative of a speed of the transmission input shaft. The drive line assembly yet further includes a transmission driven by the transmission input shaft and having a first speed clutch, a second speed clutch, and a directional clutch, and a controller. The controller is operable to determine a torque converter ratio from the engine speed signal and the transmission speed signal and determine an engine load based on the torque converter ratio. The controller is further operable to control engagement of the first speed clutch, the second speed clutch and the directional clutch based on the engine load. A method controlling a drive line assembly is also disclosed.

Claims

1. A drive line assembly for a work machine comprising:

an engine driving an engine output shaft;

an engine speed sensor which generates engine speed signals indicative of a speed of said engine output shaft;

a torque converter driven by said output shaft which drives a transmission input shaft;

a transmission speed sensor which generates transmission speed signals indicative of a speed of said transmission input shaft;

a transmission driven by said transmission input shaft and having a first speed clutch, a second speed clutch, and a directional clutch; and

a controller operable to (i) determine a torque converter ratio from said engine speed signal and said transmission speed signal (ii) determine a transmission load based on said torque converter ratio, and (iii) control engagement of said first speed clutch, disengagement of said second speed clutch, and disengagement and reengagement of said directional clutch based on said transmission load.

2. The apparatus of claim 1, wherein:

said controller determines a release delay time corresponding to said load, and

said controller delays a release of said first speed clutch by said release delay time.

3. The apparatus of claim 1, wherein:

said controller determines a speed clutch slip period corresponding to said load, and

said controller controls slip of said second speed clutch during said speed clutch slip period.

4. The apparatus of claim 3, wherein:

said controller determines a speed clutch modulation pressure corresponding to said load, and

said controller limits maximum pressure reached at the end of said speed clutch slip period to said speed clutch modulation pressure.

5. The apparatus of claim 1, wherein:

said controller determines a directional clutch slip period corresponding to said load, and

said controller controls slip of said directional clutch during said directional clutch slip period.

6. The apparatus of claim 5, wherein:

said controller determines a directional clutch ramp pressure corresponding to said load, and

said controller controls limits pressure reached at the beginning of said directional clutch slip period to said directional clutch modulation pressure.

7. The apparatus of claim 6, wherein:

said controller determines a directional clutch hold pressure corresponding to said load, and

said controller limits minimum pressure supplied to said directional clutch.

8. The apparatus of claim 1, wherein said engine load is divided into a number of distinct load ranges levels on torque converter ratio.

9. The apparatus of claim 8, wherein said controller modifies said load level based on said engine speed signal.

15. The method of claim 4, further comprising the steps of:

determining a directional clutch ramp pressure corresponding to the load; and

limiting the pressure supplied at the beginning of the directional clutch slip period to the directional clutch modulation pressure.

16. The method of claim 15, further comprising the steps of:

determining a directional clutch hold pressure corresponding to the load; and

limiting the minimum pressure supplied to the directional clutch to the directional clutch minimum pressure.

18. The method of claim 16, further comprising the step of modifying the load level based on the engine speed signal.

10. A method for controlling a drive line assembly having (i) an engine driving an engine output shaft, (ii) an engine speed sensor which generates engine speed signals indicative of a speed of the engine output shaft, (iii) a torque converter driven by the output shaft which drives a transmission input shaft, (iv) a transmission speed sensor which generates transmission speed signals indicative of a speed of the transmission input shaft, (v) a transmission driven by the transmission input shaft and having a first speed clutch, a second speed clutch, and a directional clutch, and (vi) a controller, comprising the steps of:

determining a torque converter ratio from the engine speed signal and the transmission speed signal with the controller;

determining a transmission load based on the torque converter ratio with the controller; and

controlling engagement of the first speed clutch, the second speed clutch and the directional based on the transmission load with the controller.

11. The method of claim 10, further comprising the steps of:

determining a release delay time corresponding to the load; and

delaying the release of the first speed clutch by the release delay time.

12. The method of claim 10, further comprising the steps of:

determining a speed clutch slip period corresponding to the load; and

controlling slip of the second speed clutch during the speed clutch slip time.

13. The method of claim 10, further comprising the steps of:

determining a speed clutch modulation pressure corresponding to the load; and

limiting the maximum pressure reached at the end of the speed clutch slip period to the speed clutch modulation pressure.

14. The method of claim 10, further comprising the steps of:

determining a directional clutch slip period corresponding to the load; and

controlling slip of the directional clutch during the directional clutch slip period.

17. The method of claim 10, further comprising the step of dividing the engine load into a number of distinct load levels based on torque converter ratio.