The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 17, 1977
Filed:
Jul. 07, 1975
Robert L Woods, Kensington, MD (US);
Karl N Reid, Jr, Stillwater, OK (US);
Rajamouli Gunda, Rochester, MI (US);
Oklahoma State University, Stillwater, OK (US);
Abstract
This invention describes a system of control for a power source-transmission-load system such as might be used on an off-the-road vehicle, for example. The power source is an internal combustion engine having a known optimum characteristic of desired manifold vacuum versus engine speed. The transmission is a hydrostatic or hydromechanical transmission having infinitely variable speed ratio and having a control means for varying said speed ratio. The control system includes a transducer means for measuring engine speed and converting this quantity into an analog fluid pressure proportional to the speed. This analog fluid pressure proportional to speed is modified in a function generator to produce an analog fluid pressure which is proportional to the desired manifold vacuum as a function of engine speed. Means are provided for measuring the actual manifold vacuum and for comparing the actual manifold vacuum with the desired manifold vacuum on a continuous basis. This comparison produces an error signal which is amplified and used to control a hydraulic system to operate the control means in order to vary the transmission ratio of the hydrostatic or hydromechanical transmission to obtain a speed ratio such that will provide optimum engine conditions.