Hydrostatic transmission with fixed fluid capacity ratio between pump and motor
AssigneeSundstrand Corporation
InventorAllan I. Hutson
Life of this patent
Estimating the term…
Abstract
The present invention is directed to a compact, lightweight and inexpensive hydrostatic transmission which in the preferred form has a variable displacement and reversible pump placed in side-by-side relationship with a fluid motor and wherein the transmission has a multisection housing with a uniform width center section forming both the pump chamber and the motor chamber. The fluid capacity of the pump and the fluid capacity of the motor are proportional to their widths and the ratio of the fluid capacity remains constant as various width center sections are used.
Claims23
A hydrostatic transmission comprising a hydraulic pump driven by an input shaft and in fluid communication with a hydraulic motor having an output shaft, said pump having a pump rotating element which at least in part generates a pumping action and is operatively connected to said input shaft, said motor having a motor rotatable element operatively connected to the output shaft and subjected to fluid flow from said pump and at least in part providing a rotating output to said output shaft, a housing having a center section of uniform width and located between a pair of side sections, said center section being provided with a first opening of uniform cross section at least in part forming a pumping chamber and extending the width of said center section, said center section having a second opening of uniform cross section at least in part forming a motor chamber and also extending the width of said center section, said center section being of substantially the same width as said pumping chambers, said pumping chamber containing said pump rotating element with the fluid capacity of said pump being substantially proportional to the width of said pumping chamber, said motor chamber containing said motor rotatable element with the fluid capacity of said motor being substantially proportional to the width of said motor chamber, and said pumping chamber and said motor chamber being in side-by-side relationship, and wherein a transmission of selectable capacity which can be obtained by utilizing a common pair of housing side sections and selecting a width of the center section to provide the desired transmission capacity and wherein a ratio of pump capacity to motor capacity remains constant regardless of the width of center section selected.
A variable ratio hydrostatic transmission comprising a housing having a hydraulic pump driven by an input shaft and in fluid communication with a hydraulic motor having an output shaft with one of said pump and motor is a variable displacement unit, said pump having a pump rotating element which at least in part generates a pumping action and is operatively connected to said input shaft, said motor having a rotatable motor element operatively connected to the output shaft and subjected to fluid flow from said pump to at least in part provide a rotating output, said housing having a constant width center section located between a pair of side sections, said center section having a first opening of uniform cross section in part forming a pumping chamber extending with width of said center section and containing said pump rotating element, said center section having a second opening of uniform cross section in part forming a motor chamber extending the width of said center section and containing said motor rotatable element, said pumping chamber and said motor chamber being in side-by-side relationship and perpendicular to the input and output shafts, said pump having a fluid capacity substantially proportional to the width of said pump chamber and said motor having a fluid capacity substantially proportional to the width of said motor chamber, and wherein said hydrostatic transmission may be of variable capacity by selecting the width of the center section of said housing while utilizing a common pair of said housing side sections and wherein the ratio of fluid capacity of said variable displacement unit in its maximum displacement position relative to the fluid capacity of the other of said units is kept constant.
A hydrostatic transmission adapted to provide propulsion for a vehicle having an engine and a drive axle displaced from said engine, said hydrostatic transmission including a variable displacement hydraulic pump and a hydraulic motor mounted within a single multi section housing with the hydraulic pump and motor being in side-by-side relationship and in fluid communication with each other, said pump having a pump rotating element connected to an input shaft, said motor having a motor rotatable element connected to an output shaft, said pump input shaft being adapted to be driven by said engine, said motor output shaft being adapted to drive said axle of said vehicle, said housing comprising a constant width center section located between a pair of side sections said center section of said housing being of substantially the same width as said rotating element and said motor rotatable element, said housing center section having a first constant cross section opening passing therethrough and at least in part forming a pump chamber containing said pump rotating element with said pump having a maximum fluid capacity proportional to the width of said pump chamber, said central housing section having a second constant cross-section opening passing therethrough at least in part forming a motor chamber containing said motor rotatable element with said motor having a fluid capacity proportional to the width of said motor chamber, and said pump chamber and said motor chamber having the same width substantially equal to the width of said center section, and wherein said hydrostatic transmission may be of variable capacity by selecting the width of the center section of said housing while utilizing a common pair of said housing side sections and wherein the ratio of fluid capacity of said variable displacement pump in its maximum displacement position relative to the fluid capacity of said hydraulic motor is kept constant.
Dependencies are inferred from the claim text.