High speed downshift management

Patent metadata

Field	Value
Publication number	US-10046768-B2
Application number	US-201414560992-A
Country	US
Kind code	B2
Filing date	Dec 4, 2014
Priority date	Dec 4, 2014
Publication date	Aug 14, 2018
Grant date	Aug 14, 2018

Abstract

In order to reduce drivetrain component wear and tear, a machine monitors for an impending downshift and automatically slows the machine to a speed that keeps engine rpm below a target engine rpm before the downshift is completed. A controller in the machine determines the current speed of the machine and then slows the machine to a new speed associated with the target rpm in the new gear. The controller may simply apply the brakes to slow the machine to the new speed independently of the process of changing gears or may actively delay the gear change until the new speed is achieved.

First claim

What is claimed is:

1. A system for controlling wear to drivetrain components during downshifting in a machine, the system comprising:
a transmission;
a gear selector electronically coupled to the transmission;
a brake mechanism configured for remote activation;
a controller coupled to the gear selector and the brake mechanism, the controller configured to:
receive a signal via the gear selector to change the transmission from a current gear to a new gear, the new gear being lower than the current gear;
calculate a new revolutions per minute (rpm), of a drivetrain component, corresponding to operating the transmission in the new gear,
wherein the drivetrain component is one of a torque converter or an engine;

determine that the new rpm is above a target rpm;
determine a new speed of the machine at which the new rpm in the new gear will be at or below the target rpm; and
activate the brake mechanism to slow the machine to the new speed prior to the transmission engaging the new gear; and
after changing to the new gear, when an actual new engine rpm is above an upper threshold engine rpm, increase an activation level of the brake mechanism to slow the machine until the upper threshold engine rpm is reached,
the upper threshold engine rpm exceeding the target rpm.

2. The system of claim 1 , wherein the controller is further configured to
determine a current speed of the machine.

3. The system of claim 1 , wherein the controller is further configured to:
delay changing the transmission to the new gear until the new speed is reached.

4. A method of controlling wear to drivetrain components in a machine during downshifting, the method comprising:
receiving, by a controller and from a gear selector, a request to downshift to a new gear;
prior to performing the downshift to the new gear, determining, by the controller, a new revolutions per minute (rpm), of a drivetrain component, corresponding to the new gear,
wherein the drivetrain component is one of a torque converter or an engine;

when the new rpm is above a target rpm, determining, by the controller, a new speed of the machine that corresponds to the target rpm when in the new gear;
applying, by the controller, a remotely activated brake to slow the machine to the new speed prior to shifting to the new gear; and
after shifting to the new gear, when a new actual engine rpm is above an upper threshold engine rpm higher than the target rpm, applying additional braking force to the brake to further slow the machine to reach the upper threshold engine rpm.

5. The method of claim 4 , wherein determining the new speed comprises looking up a known characteristic of a machine speed in the new gear vs. a slope on which the machine is operating.

6. The method of claim 4 , wherein the target rpm is in a range of 2700 rpm to 2900 rpm.

7. The method of claim 4 , further comprising:
determining that a current speed of the machine is above a threshold speed and only applying the brake when the current speed is above the threshold speed.

8. The method of claim 4 , further comprising:
delaying shifting to the new gear until the machine has reached the new speed.

9. The method of claim 4 , further comprising:
determining that the machine is overrunning the engine based on a slope of the machine, a current gear setting of the machine and an engine rpm.

10. The method of claim 4 , further comprising:
determining a current speed of the machine.

11. A method of controlling wear to drivetrain components in a machine during downshifting, the method comprising:
determining a current speed of the machine;
receiving, from a gear selector, a request to downshift from a current gear to a new gear;
prior to changing to the new gear, determining a revolutions per minute (rpm) of a drivetrain component in the new gear,
wherein the drivetrain component is one of a torque converter or an engine;

when the rpm of the drivetrain component in the new gear is above a target rpm, determining a new speed at which the rpm of the drivetrain component will remain below the target rpm;
slowing, using a remotely activated brake mechanism, the machine to the new speed prior to changing to the new gear; and
after changing to the new gear, further slowing the machine using the remotely activated brake mechanism to reach an upper threshold target rpm when an actual rpm of the drivetrain component exceeds the upper threshold target rpm.

12. The method of claim 11 , further comprising:
monitoring an actual speed of the machine; and
delaying the change to the new gear until the machine reaches the new speed.

13. The method of claim 11 , wherein the target rpm is an engine rpm of about 2700 rpm.

14. The method of claim 13 , wherein the upper threshold target rpm is about 3300 rpm at the drivetrain component.

15. The method of claim 11 , wherein determining the rpm of the drivetrain component in the new gear comprises predetermining a run-out speed for the machine in the new gear at a current slope.

16. The method of claim 11 , wherein determining the new speed of the machine comprises:
determining a slope of a grade on which the machine is moving;
using a lookup table to determine the new speed as a function of the new gear and the slope.

Assignees

• Caterpillar Inc

Inventors

• Tinker Matthew Michael
• Anderson Randy T
• Anderson Michael D

Classifications

• B60W2552/15

  Road slope, i.e. the inclination of a road segment in the longitudinal direction · CPC title

• B60W30/18063

  Creeping · CPC title

• B60W2300/152

  Tractors · CPC title

• B60W30/18109 Primary

  Braking · CPC title

• B60W10/06

  including control of combustion engines · CPC title