Transmisson for power take-off

• US 6,692,395 B2
• Filed: 02/25/2002
• Issued: 02/17/2004
• Est. Priority Date: 02/25/2002
• Status: Active Grant

• Current Assignee: Deere & Company
• Original Assignee: Deere & Company
• Inventors: Thompson, Graham, Klabunde, Barbara, Rodeghiero, Reno Antonio, Stettler, Werner, Skotnikov, Andrey Valeryevich
• Primary Examiner(s): Parekh, Ankur
• Application Number:
  US10/082,390
• Publication Number:
  US 20030162619A1
• Time in Patent Office: 722 Days
• Field of Search: 475/1, 475/2, 475/5, 475/72, 475/76, 475/77, 74/154, 74/156.3, 74/158.4
• US Class Current: 475/77
• CPC Class Codes: B60K 17/28 characterised by arrangement, location, or type of power take-off
• CPC Class Codes: F16H 47/04 the mechanical gearing being of the type with members having orbital motion

Abstract

A PTO transmission includes a split power transmission unit having an output member connected to a PTO shaft, a first input connected to an engine output shaft and a second input connected the output of a variable speed drive unit. A control unit controls the speed of the variable speed drive unit as a function of sensed engine speed and maintains the PTO shaft at a constant speed. The split power transmission is preferably a planetary gear unit. The variable speed drive unit preferably includes a variable displacement hydrostatic pump driving a fixed displacement hydrostatic motor which drives a sun gear of the planetary gear unit. This system transmits power to the PTO shaft from both the engine and from the variable speed drive unit. The control unit may also control the variable speed drive unit so that the speed of the PTO shaft is maintained at a desired ratio with respect to the ground speed, or so that the speed of the PTO shaft is maintained at a speed set by an operator.

Claims

1. A system for transmitting power from an engine shaft to a PTO shaft, comprising:

a transmission having a first input member coupled to the engine shaft, a second input member and an output member coupled to the PTO shaft, the output member having a rotation speed which is a function of a rotation speed of the first and second input members;

a variable speed drive unit connected to the second input member;

a ground speed sensor generating a ground speed signal;

an operator controlled ratio setting unit generating a ratio signal; and

a control unit operatively coupled to the variable speed drive unit, the control unit receiving the ground speed signal and the ratio signal, and the control unit generating control signals which cause a rotation speed of the variable speed drive unit to vary so as to maintain a desired ratio between a ground speed and the rotation speed of the output member.

2. The system of claim 1, further comprising:

a control unit operatively coupled to the variable speed drive unit, the control unit generating control signals which cause a rotation speed of the variable speed drive unit to vary so that the rotation speed of the output member remains substantially constant despite variations in the rotation speed of the engine shaft.

3.The system of claim 2, further comprising;

a speed sensor sensing the rotation speed of the first input member and supplying a rotation speed signal to the control unit.

3. The system of claim 1, wherein the variable speed drive unit comprises:

a hydraulic pump drivingly connected to the first input member; and

a hydraulic motor driven by the pump and connected to the second input member of the transmission.

5. The system of claim 1, wherein the transmission comprises:

a planet carrier fixed for rotation with the engine shaft;

planet gears rotatably mounted on the planet carrier;

a ring gear attached for rotation with the output member and in meshing engagement with the planet gears;

a sun gear in meshing engagement with the planet gears and drivingly connected to the variable speed drive unit.

6. The system of claim 1, further comprising:

an operator controlled speed setting unit generating a desired speed signal;

an output member speed sensor generating an output member speed signal; and

a control unit operatively coupled to the variable speed drive unit, the control unit receiving the desired speed signal and the output member speed signal, and the control unit generating control signals which cause a rotation speed of the variable speed drive unit to vary so as to maintain the rotation speed of the output member at a desire speed.

4. The system of claim 4, wherein

the pump is a variable displacement hydraulic pump and the motor is a fixed displacement motor.

7. A system for transmitting power from an engine shaft to a PTO shaft, comprising:

a planet carrier drivingly connected to the engine shaft;

planet gears rotatably mounted on the planet carrier;

a ring gear drivingly connected to the PTO shaft and in meshing engagement with the planet gears;

a sun gear in meshing engagement with the planet gears;

a variable speed drive mechanism for rotating the sun gear at a variable speeds;

a ground speed sensor generating a ground speed signal;

an operator controlled ratio setting unit generating a ratio signal; and

a control unit operatively coupled to the variable speed drive unit, the control unit receiving the ground speed signal and the ratio signal, and the control unit generating control signals which cause a rotation speed of the variable speed drive mechanism to vary so as to maintain a desired ratio between a ground speed and the rotation speed of the ring gear.

8. The system of claim 8, wherein the variable speed drive mechanism comprises:

a speed sensor generating a planet carrier speed signal;

a control unit receiving the speed signal and generating a control signal as a function thereof; and

a variable speed drive unit receiving the control signal and drivingly coupled to the sun gear, the control unit and the drive unit cooperating so that the PTO shaft rotates a constant speed despite variations in engine shaft speed.

9. The system of claim 8, wherein the drive mechanism comprises:

a variable speed drive motor having a motor drive shaft; and

drive gear fixed for rotation with the motor drive shaft and in meshing engagement with the sun gear.

10. The system of claim 8, wherein the drive mechanism comprises:

a first drive gear fixed for rotation with the planet carrier;

a variable displacement pump having an input shaft driven by the first drive gear;

a fixed displacement variable speed hydraulic motor hydraulically driven by the pump and having a variable speed motor drive shaft; and

a second drive gear in meshing engagement with the sun gear and fixed for rotation with the motor drive shaft.

11. A system for transmitting power from an engine shaft to a PTO shaft, comprising:

a planet carrier drivingly connected to the engine shaft;

planet gears rotatably mounted on the planet carrier;

a ring gear drivingly connected to the PTO shaft and in meshing engagement with the planet gears;

a sun gear in meshing engagement with the planet gears;

a variable speed drive mechanism for rotating the sun gear at a variable speed;

an operator controlled speed setting unit generating a desired speed signal;

an output member coupled between the ring gear and the PTO shaft;

an output member speed sensor generating an output member speed signal; and

a control unit operatively coupled to the variable speed drive unit, the control unit receiving the desired speed signal and the output member speed signal, and the control unit generating control signals which cause a rotation speed of the variable speed drive mechanism to vary so as to maintain the rotation speed of the output member at a desired speed.