Kevin Richard Graf

US Patent:

49514628, Aug 28, 1990

Filed:

Jun 5, 1989

Appl. No.:

7/361516

Inventors:

Kevin J. Graf - Eden Prairie MN

Assignee:

Eaton Corporation - Cleveland OH

International Classification:

F16H 6142

US Classification:

60444

Abstract:

A closed-loop hydrostatic transmission is disclosed of the type with a fluid pump (10) and a fluid motor (12), both of which are variable displacement. A pair of stroking cylinders (36,38) varies the displacement of the motor between minimum displacement and maximum displacement, under the control of a motor stroking valve (70) which includes a stroking valve member (90) movable in response to changes in fluid pressure in a pressure chamber (110). The displacement of the pump is controlled by a main controller (50) in response to movement of an input handle (60). Whenever the handle (60) is moved to the neutral position, a neutral switch (122) is closed, thus generating a neutral signal which is transmitted to an electromagnetic valve member (114), which controls the pressure in the fluid pressure chamber (110) to command the motor to maximum displacement. With the motor at maximum displacement, subsequent movement of the handle (60) away from the neutral position, to begin to propel the vehicle, results in a smoother start-up of the vehicle because the motor is at maximum displacement (a high-torque, low-speed condition). Starting the vehicle with the motor at maximum displacement also reduces the amount of rise of system pressure above the relief valve setting, thus reducing the amount of heat generated and the amount of horsepower wasted.

US Patent:

50170945, May 21, 1991

Filed:

Mar 12, 1990

Appl. No.:

7/491776

Inventors:

Kevin J. Graf - Eden Prairie MN
James J. Hastreiter - Eden Prairie MN
Duane A. Anderson - Edina MN

Assignee:

Eaton Corporation - Cleveland OH

International Classification:

F04B 4906
F04B 126

US Classification:

417218

Abstract:

A control system (33, 41) is disclosed of the type used to control the displacement of a variable displacement pump (11) having stroking cylinders (25, 27). The control system includes a pair of ON-OFF electromagnetic valves (49, 51) and a proportional valve (85). When a first direction of operation is selected, a first direction command signal (43) is transmitted to the first ON-OFF valve (40) such that control pressure from the charge pump (17) flows through the valve (49), then through the proportional valve (85) and through the valve (51) to the reservoir (75) until the proportional valve (85), in response to an increasing displacement signal (47), moves from its minimum displacement position (FIG. 1) toward a position corresponding to the desired displacement of the pump. With the control system of the present invention, two of the three electromagnetic valves (49, 51, 85) would have to fail, such as being stuck in an open position, in order for the vehicle operator to be unable to bring the vehicle to a safe stop.

US Patent:

61589691, Dec 12, 2000

Filed:

Sep 16, 1999

Appl. No.:

9/397696

Inventors:

Kevin J. Graf - Eden Prairie MN
Jerry D. Schrag - Savage MN

Assignee:

Eaton Corporation - Cleveland OH

International Classification:

F04B 126

US Classification:

4172221

Abstract:

A variable displacement hydrostatic pump (11) having its displacement varied by a controller (17) in response to movement of a manual control lever (95) from a neutral position (FIG. 1). The vehicle has at least one other device (125,127) which provides an electrical output signal (133) indicating when operation of the pump (11) is "acceptable", in terms of either vehicle performance or operator safety. Associated with the control lever (95) is an input shaft (103) defining at least one stop surface (121,123). A solenoid assembly (109) has a moveable plunger (111), disposed adjacent the stop surfaces, and moveable between a retracted position (FIG. 4a) and an extended position (FIGS. 2 and 4), engaging one of the stop surfaces, when the output signal (133) indicates that operation of the pump is not acceptable.