Method and apparatus for transmission control during braking

• US 6,269,295 B1
• Filed: 11/16/2000
• Issued: 07/31/2001
• Est. Priority Date: 11/30/1999
• Status: Expired due to Term

• Current Assignee: Caterpillar Incorporated, IMEDICA Corporation
• Original Assignee: Caterpillar Incorporated
• Inventors: Hubbard, Milton C., Schoenberg, Matthew F., Gaugush, Susan J., Wulfert, Wayne J., Palmer, Marvin K.
• Primary Examiner(s): Camby, Richard M.
• Application Number:
  US09/713,931
• Time in Patent Office: 257 Days
• Field of Search: 701/51, 701/53, 701/55, 701/56, 701/58, 701/70, 701/95, 192/215, 192/220, 192/220.1, 477/98, 477/95
• US Class Current: 701/55
• CPC Class Codes: B60T 11/103 in combination with other control devices conjoint control of brake system and at least another sub-unit B60W10/188
• CPC Class Codes: B60W 10/10 including control of change-speed gearings
• CPC Class Codes: B60W 10/18 including control of braking systems
• CPC Class Codes: B60W 2540/12 Brake pedal position
• CPC Class Codes: B60W 30/18109 Braking
• CPC Class Codes: B60W 30/1819 Propulsion control with control means using analogue circuits, relays or mechanical links
• CPC Class Codes: B60Y 2200/14 Trucks; Load vehicles, Busses
• CPC Class Codes: B60Y 2200/41 Construction vehicles, e.g. graders, excavators
• CPC Class Codes: F16H 59/54 dependent on signals from the brakes, e.g. parking brakes

Abstract

A method for operating machine transmission during braking, includes obtaining data relating to brake pedal position, machine velocity, machine engine speed, current transmission operating gear, and lowest operating gear. Next, downshifting thresh holds are set based on whether pedal position is in a downshift mode or a braking mode. Next, the transmission is downshifted if the machine velocity and machine engine speed are less than the downshifting thresh holds, and if the transmission operating gear is not the lowest operating gear. Next, the transmission is neutralized if the pedal position is in a neutralizing mode, if the velocity is less than a neutralizing thresh hold velocity, and if the transmission is in the lowest operating gear. Finally, the above steps are repeated until the transmission is neutralized.

Claims

1. A method for operating a transmission of a machine comprising an engine, the transmission and a brake pedal operated brake, wherein the brake pedal may be positioned in a downshifting mode, braking mode or neutralizer mode, the method comprising:

(A) obtaining data relating to brake pedal position, machine velocity, machine engine speed, current transmission operating gear, and lowest operating gear;

(B) setting downshifting thresh holds based on whether pedal position is in a downshift mode or a braking mode;

(C) downshifting the transmission if the machine velocity and machine engine speed are less than the downshifting thresh holds, and if the transmission operating gear is not the lowest operating gear;

(D) neutralizing the transmission if the pedal position is in a neutralizing mode, if the velocity is less than a neutralizing thresh hold velocity, and if the transmission is in the lowest operating gear; and

(E) repeating steps (A) through (D) until the transmission is neutralized.

2. The method of claim 1, further comprising:

(F) obtaining data relating to pedal position, including a current position and a maximum depressed depression position (MDDP);

(G) if the current position exceeds the MDDP, resetting MDDP to the current position and repeating step (F);

(H) engaging the transmission and allowing machine movement if the pedal position has moved a thresh hold amount away from the maximum depressed depression position;

(I) if brake pedal is not fully released, repeating step (F); and

(J) returning control to the automatic transmission controller.

3. A computerized system for operating a transmission of a machine comprising an engine, the transmission and a brake pedal operated brake, wherein the brake pedal may be positioned in a downshifting mode, braking mode or neutralizer mode, the system comprising computer hardware and the following software instructions:

(A) instructions for obtaining current data relating to brake pedal position, machine velocity, machine engine speed, current transmission operating gear, and lowest operating gear;

(B) instructions for setting downshifting thresh holds based on whether pedal position is in a downshift mode or a braking mode;

(C) instructions for generating a transmission downshifting signal if the machine velocity and machine engine speed are less than the downshifting thresh holds, and if the transmission operating gear is not the lowest operating gear;

(D) instructions for generating a transmission neutralizing signal if the pedal position is in a neutralizing mode, if the velocity is less than a neutralizing thresh hold velocity, and if the transmission is in the lowest operating gear; and

(E) instructions for repeating instructions (A) through (D) until the transmission is neutralized.

4. The system of claim 3, further comprising:

(F) instructions for obtaining data relating to pedal position, including a current position and a maximum depressed depression position (MDDP);

(G) instructions for repeating instructions (F) if the current position exceeds the MDDP and for resetting MDDP to the current position; and

(H) instructions for engaging the transmission and allowing machine movement if the pedal position has moved a thresh hold amount away from the maximum depressed depression position;

(I) instructions to repeat instructions (F) if brake pedal is not fully released; and

(J) instructions to return control to the automatic transmission controller.

5. A computer readable medium comprising software for operating a transmission of a machine comprising an engine, the transmission and a brake pedal operated brake, wherein the brake pedal may be positioned in a downshifting mode, braking mode or neutralizer mode, the medium comprising:

(A) instructions for obtaining current data relating to brake pedal position, machine velocity, machine engine speed, current transmission operating gear, and lowest operating gear;

(B) instructions for setting downshifting thresh holds based on whether pedal position is in a downshift mode or a braking mode;

(C) instructions for generating a transmission downshifting signal if the machine velocity and machine engine speed are less than the downshifting thresh holds, and if the transmission operating gear is not the lowest operating gear;

(D) instructions for generating a transmission neutralizing signal if the pedal position is in a neutralizing mode, if the velocity is less than a neutralizing thresh hold velocity, and if the transmission is in the lowest operating gear; and

(E) instructions for repeating instructions (A) through (D) until the transmission is neutralized.

6. The medium of claim 5, further comprising:

(F) instructions for obtaining data relating to pedal position, including a current position and a maximum depressed depression position (MDDP);

(G) instructions for repeating instructions (F) if the current position exceeds the MDDP and for resetting MDDP to the current position; and

(H) instructions for engaging the transmission and allowing machine movement if the pedal position has moved a thresh hold amount away from the maximum depressed depression position;

(I) instructions to repeat instructions (F) if brake pedal is not fully released; and

(J) instructions to return control to the automatic transmission controller.