Transmission control system
AssigneeNACCO Materials Handling Group, Inc.
InventorRobert Lee Chess
Life of this patent
Estimating the term…
Abstract
A transmission system includes a Central Processing Unit (CPU) that controls truck braking energy by sharing energy dissipation between clutch packs. The CPU reduces engine speed and then slips the two clutch packs at the same time to maintain a reduced turbine speed for a torque converter. In another aspect of the transmission system, energy loss is reduced during high draw bar pull conditions. The engine speed is modulated to trim energy peaks at low pushing or pulling speeds. An additional transmission gear reduction restores the lost pushing or pulling forces while generating less heat in the torque converter.
Claims45
A method for controlling speed of a vehicle, comprising:
- slipping a first clutch while the vehicle engine is operating at a reduced engine speed for decelerating the vehicle;
- and
- slipping a second clutch at the same time the first clutch is being slipped, the second clutch applying a slipping force corresponding to a current direction of vehicle travel and opposite to a slipping force applied by the first clutch, the slipping force of the second clutch maintaining a torque converter at an approximately constant low speed.
A method for controlling speed of a vehicle, comprising:
- detecting a braking condition;
- slipping a first clutch during the braking condition while the vehicle engine is operating at a reduced engine speed;
- slipping a second clutch during the braking condition to maintain a torque converter at an approximately constant low speed;
- identifying a power reversal mode for the braking condition;
- progressively reducing pressure in the second clutch down to about zero after the vehicle speed approaches zero;
- progressively increasing pressure in the first clutch after the vehicle speed reaches approximately zero;
- and
- progressively increasing the engine speed after the vehicle speed reaches approximately zero.
A method for controlling speed of a vehicle, comprising:
- detecting a braking condition;
- slipping a first clutch during the braking condition while the vehicle engine is operating at a reduced engine speed;
- slipping a second clutch during the braking condition to maintain a torque converter at an approximately constant low speed;
- identifying an accelerator braking mode for the braking condition by monitoring an accelerator position setting, a vehicle speed, and direction sensor;
- progressively reducing pressure in the second clutch down to a low level as the vehicle speed approaches zero;
- increasing pressure in the second clutch after the vehicle speed approximately reaches zero while maintaining a constant pressure in the first clutch;
- and
- maintaining a constant idle speed for the engine after the vehicle speed approximately reaches zero.
A method for controlling a vehicle, comprising:
- detecting a low energy efficiency condition in the vehicle;
- changing or maintaining the vehicle in a low gear;
- and
- automatically reducing engine speed in the vehicle in combination with operating the vehicle in the low gear when the low energy efficiency condition is detected to automatically maintain an approximately constant vehicle torque below a maximum torque value provided by the low gear.
A braking system, comprising:
- a first clutch pack associated with a first direction of vehicle travel;
- a second clutch pack associated with a second direction of vehicle travel;
- and
- a processor activating both the first clutch pack and the second clutch pack at the same time to distribute braking energy between the first clutch pack and the second clutch pack during clutch pack braking.
A method for controlling speed of a vehicle, comprising:
- progressively reducing pressure in a first clutch down to a low level as the vehicle speed approaches zero;
- increasing pressure in the first clutch after the vehicle speed approximately reaches zero while maintaining a constant pressure in a second clutch;
- and
- maintaining a constant idle speed for a vehicle engine after the vehicle speed approximately reaches zero.
A braking system, comprising:
- a first clutch pack associated with a first direction of vehicle travel;
- a second clutch pack associated with a second opposite direction of vehicle travel;
- and
- a processor progressively reducing pressure in the first clutch pack down to a low level as vehicle speed approaches zero and increasing pressure in the first clutch pack after the vehicle speed approximately reaches zero while maintaining a constant pressure in the second clutch pack, the processor maintaining a constant idle speed for the engine after the vehicle speed approximately reaches zero.
Dependencies are inferred from the claim text.