Reciprocating mower unit, system and methods

Patent metadata

Field	Value
Publication number	US-11895946-B2
Application number	US-201917431884-A
Country	US
Kind code	B2
Filing date	Feb 19, 2019
Priority date	Feb 19, 2019
Publication date	Feb 13, 2024
Grant date	Feb 13, 2024

Abstract

A reciprocating mower unit (14) comprises a reduction gear (54) and a crank mechanism (56) arranged within a housing (24). The reduction gear (54) receives input rotary motion from a transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft (58) at a second, relatively lower, rotation speed, whereas the crank mechanism (56) converts the output rotary motion of the gear output shaft (58) to an oscillating, anti-phase motion of a pair of mowing blades (32a, 32b) about a common oscillation axis (A1). The reciprocating mower unit (14) comprises an input shaft (48) provided with a coupling interface (49) for releasably coupling the input shaft (48) to the transmission shaft.

First claim

The invention claimed is:

1. A reciprocating mower unit configured to be driven by a drive unit via a transmission shaft arranged within a transmission tube, the reciprocating mower unit comprising:
a housing;
a reduction gear arranged within the housing, the reduction gear being configured to receive an input rotary motion from the transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft at a second, relatively lower, rotation speed; and
a crank mechanism arranged within the housing, the crank mechanism being configured to convert the output rotary motion of the gear output shaft to an oscillating motion of a pair of mowing blades oscillating in mutual anti-phase about a common oscillation axis, wherein the reciprocating mower unit comprises an input shaft for receiving said input rotary motion from the transmission shaft, wherein the input shaft is provided with a coupling interface for releasably coupling the input shaft to the transmission shaft.

2. The reciprocating mower unit according to claim 1 , wherein the coupling interface comprises splines for axially sliding into rotational engagement with mating splines of the transmission shaft.

3. The reciprocating mower unit according to claim 1 , wherein the housing comprises a clamping arrangement for clamping the housing to the transmission tube.

4. A vegetation cutter system comprising:
the drive unit comprising a motor and the transmission shaft of claim 1 arranged within the transmission tube;
the reciprocating mower unit; and
a clearing saw unit configured to rotate a clearing saw blade, wherein the reciprocating mower unit and the clearing saw unit are configured to be alternatingly connected to the transmission shaft.

5. The reciprocating mower unit of claim 1 , wherein the reduction gear is a two-stage reduction gear comprising a first gear connected to corotate with the input shaft, a second gear in mesh with the first gear, a third gear connected to corotate with the second gear, and a fourth gear configured to co-rotate with a crank of the crank mechanism, the fourth gear being in mesh with the third gear, wherein the first gear has a first number of teeth, the second gear has a second number of teeth, the third gear has a third number of teeth, and the fourth gear has a fourth number of teeth, wherein the second gear has more teeth than the first gear, and the fourth gear has more teeth than the third gear.

6. The reciprocating mower unit according to claim 5 , wherein the first gear has 7-14 teeth; the second gear has 20-30 teeth; the third gear has 11-19 teeth, and the fourth gear has 26-40 teeth.

7. The reciprocating mower unit of claim 1 , wherein the crank mechanism comprises, for each of the mowing blades, a respective four-bar linkage configured to oscillate the respective blade in response to rotation of the gear output shaft, each of the four- bar linkages comprising
a fixed link between a rotation axis of the gear output shaft and the common oscillation axis;
a respective input link configured as a crank attached to the gear output shaft;
a respective output link configured as a crank j ournaled to pivot about the common oscillation axis; and
a respective coupler link interconnecting the respective input and output links, wherein, for each of said four-bar linkages, a link ratio between the input link and the fixed link of at least 1:10.

8. The reciprocating mower unit according to claim 7 , having a link ratio between the input link and the coupler link of at least 1:8.

9. The reciprocating mower unit of claim 1 , wherein the crank mechanism is configured to oscillate each respective mower blade about the common oscillation axis at an oscillation angle of less than 15°.

10. A reciprocating mower unit configured to be driven by a drive unit via a transmission shaft arranged within a transmission tube, the reciprocating mower unit comprising:
a housing;
a reduction gear arranged within the housing, the reduction gear being configured to receive an input rotary motion from the transmission shaft at a first, relatively higher, rotation speed, and deliver an output rotary motion to a gear output shaft at a second, relatively lower, rotation speed; and
a crank mechanism arranged within the housing, the crank mechanism being configured to convert the output rotary motion of the gear output shaft to an oscillating motion of a pair of mowing blades oscillating in mutual anti-phase about a common oscillation axis, wherein the reciprocating mower unit comprises an input shaft for receiving said input rotary motion from the transmission shaft, wherein the input shaft is provided with a coupling interface for releasably coupling the input shaft to the transmission shaft,
wherein the reciprocating mower unit further comprises a grounding body defining a lowermost face for resting against the ground when the reciprocating mower unit is in use, wherein the grounding body is rotationally decoupled, with regard to turning about the common oscillation axis, from each mowing blade of said pair of mowing blades.

11. The reciprocating mower unit according to claim 10 , wherein the grounding body is rotationally decoupled from the housing.

12. The reciprocating mower unit according to claim 10 , wherein the grounding body is axially carried by a blade reciprocation shaft.

13. The reciprocating mower unit according to claim 12 , wherein the grounding body is axially held through a central opening of the grounding body between an upper axial stop and a lower axial stop, wherein an axial distance between the upper and lower axial stops exceeds the thickness of the grounding body adjacent the central aperture.

14. The reciprocating mower unit according to claim 13 , wherein the upper axial stop is defined by a downwards facing shoulder of the mowing blade reciprocation shaft.

15. The reciprocating mower unit according to claim 13 , wherein the lower axial stop is defined by a fastening arrangement in abutment with a shoulder of the mowing blade reciprocation shaft.

16. A method of operating a reciprocating mower, comprising:
operating a motor of a drive unit at a rotation speed of more than 8000 revolutions per minute;
operating a transmission shaft having a length of at least 1 meter at the rotation speed of the motor;
driving a first reduction gear step with an output rotary motion of the transmission shaft;
driving a second reduction gear step with an output rotary motion of the first reduction gear step; and
converting output rotary motion of the second reduction gear step to an oscillating motion of a pair of mowing blades,
wherein the reciprocating mower unit comprises an input shaft for receiving input rotary motion from the transmission shaft, wherein the input shaft is provided with a coupling interface for releasably coupling the input shaft to the transmission shaft.

Assignees

• Husqvarna Ab

Inventors

• Souri Naoki
• Miyazawa Hiroyuki

Classifications

• A01D34/76 Primary

  Driving mechanisms for the cutters · CPC title

• A01D34/404

  having cutters driven to oscillate in a horizontal plane · CPC title

• A01D34/90 Primary

  for carrying by the operator · CPC title