Low power HMT with by-pass valve
View Patent ↗A method of operating a vehicle with a hydrostatic circuit. The method includes providing a hydrostatic circuit having first and second hydraulic kits that are fluidly connected to one another by first and second fluid lines. A by-pass valve is placed between the first and second hydraulic lines and is controlled in order to actuate the by-pass valve when certain predetermined conditions are present in order to relieve pressure within the hydrostatic circuit.
1. A method of operating a vehicle with a hydrostatic circuit comprising:
providing said hydrostatic circuit having a first hydraulic kit fluidly connected to a second hydraulic kit via first and second fluid lines;
providing a by-pass valve disposed between and fluidly connected to the first and second fluid lines;
actuating the by-pass valve when a predetermined condition is present to relieve pressure in the hydrostatic circuit; and
wherein the predetermined condition is wherein a difference between a hydromechanical transmission ratio and actual vehicle speed ratio is greater than a predefined offset amount.
2. The method of claim 1 wherein the by-pass valve is opened proportionately to the difference greater than the predetermined offset amount.
3. The method of claim 1 wherein actuating a throttle causes the request for a rapid increase in torque.
4. The method of claim 1 wherein a controller is electrically connected to the by-pass valve to actuate the valve.
5. The method of claim 4 wherein the by-pass valve is a proportional valve.
6. The method of claim 1 wherein the by-pass valve is a digitally controlled valve.
7. A method of operating a vehicle with a hydrostatic circuit comprising:
providing said hydrostatic circuit having a first hydraulic kit fluidly connected to a second hydraulic kit via first and second fluid lines;
actuating the by-pass valve when a predetermined condition is present to relieve pressure in the hydrostatic circuit;
wherein the predetermined condition is wherein the vehicle is commanded to stop; and
wherein the by-pass valve is opened proportionately to a difference between HMT ratio and actual vehicle speed ratio.
8. A method of operating a vehicle with a hydrostatic circuit comprising:
providing said hydrostatic circuit having a first hydraulic kit fluidly connected to a second hydraulic kit via first and second fluid lines;
providing a by-pass valve disposed between and fluidly connected to the first and second fluid lines;
actuating the by-pass valve when a predetermined condition is present to relieve pressure in the hydrostatic circuit;
wherein the predetermined condition is wherein an engine of the vehicle is not operating; and wherein the by-pass valve is opened proportionately to vehicle speed.