Lawn mower with speed controlled shutter device

1. A lawn mower, comprising:

a work unit including a housing having a downward-facing opening and a cutter blade rotatably provided in the housing such that when rotated, the cutter blade cuts grass and generates a transport air flow flowing from the opening of the housing to inside;

a grass clippings receptacle configured to receive mowed grass clippings;

a grass clippings transport passage connecting an interior of the housing with the grass clippings receptacle;

a shutter device including a shutter configured to open and close the grass clippings transport passage and an actuator configured to open/close-drive the shutter;

a controller configured to control the shutter device; and

a speed sensor for detecting a travel speed of the lawn mower,

wherein the controller is configured to open/close-control the shutter device based on the travel speed.

2. The lawn mower according to claim 1 , wherein the controller is configured to perform a reciprocal opening and closing control to open/close-control the shutter device such that the shutter successively repeats opening and closing within a predetermined reciprocal opening degree range, the reciprocal opening degree range being varied in dependence on the travel speed.

3. The lawn mower according to claim 2 , wherein the controller is configured to set a minimum opening degree of the reciprocal opening degree range such that the minimum opening degree gets smaller with an increase in the travel speed.

4. The lawn mower according to claim 3 , wherein the controller is configured to set a maximum opening degree of the reciprocal opening degree range such that the maximum opening degree is fixed without regard to the travel speed.

5. The lawn mower according to claim 3 , wherein the controller is configured to set the minimum opening degree of the reciprocal opening degree range to a prescribed first minimum opening degree when the travel speed is equal to or lower than a prescribed travel speed determination value, and set the minimum opening degree of the reciprocal opening degree range to a prescribed second minimum opening degree smaller than the first minimum opening degree when the travel speed is higher than the travel speed determination value.

6. The lawn mower according to claim 2 , further comprising a pressure sensor provided in a part of the grass clippings transport passage located between the shutter and an end part of the grass clippings transport passage adjacent to the grass clippings receptacle, the controller being configured to start the reciprocal opening and closing control in a case where the pressure is greater than a predetermined pressure determination value at a time after a predetermined transition period has elapsed from a start of driving of the work unit.

7. The lawn mower according to claim 6 , wherein the controller is configured to fully close the shutter in a case where the pressure is lower than or equal to the pressure determination value at a time after the transition period has elapsed.

8. The lawn mower according to claim 6 , wherein the controller is configured to control the shutter device so as to position the shutter at a fully open position when the work unit is stopped.

9. The lawn mower according to claim 6 , further comprising an operation input device configured to receive an operation input from an operator to operate driving and stopping of the work unit,

wherein the controller is configured to detect start and stop of driving of the work unit based on a signal from the operation input device.

10. The lawn mower according to claim 4 , wherein the controller is configured to set the minimum opening degree of the reciprocal opening degree range to a prescribed first minimum opening degree when the travel speed is equal to or lower than a prescribed travel speed determination value, and set the minimum opening degree of the reciprocal opening degree range to a prescribed second minimum opening degree smaller than the first minimum opening degree when the travel speed is higher than the travel speed determination value.

11. The lawn mower according to claim 3 , further comprising a pressure sensor provided in a part of the grass clippings transport passage located between the shutter and an end part of the grass clippings transport passage adjacent to the grass clippings receptacle, the controller being configured to start the reciprocal opening and closing control in a case where the pressure is greater than a predetermined pressure determination value at a time after a predetermined transition period has elapsed from a start of driving of the work unit.

12. The lawn mower according to claim 4 , further comprising a pressure sensor provided in a part of the grass clippings transport passage located between the shutter and an end part of the grass clippings transport passage adjacent to the grass clippings receptacle, the controller being configured to start the reciprocal opening and closing control in a case where the pressure is greater than a predetermined pressure determination value at a time after a predetermined transition period has elapsed from a start of driving of the work unit.

13. The lawn mower according to claim 5 , further comprising a pressure sensor provided in a part of the grass clippings transport passage located between the shutter and an end part of the grass clippings transport passage adjacent to the grass clippings receptacle, the controller being configured to start the reciprocal opening and closing control in a case where the pressure is greater than a predetermined pressure determination value at a time after a predetermined transition period has elapsed from a start of driving of the work unit.

14. The lawn mower according to claim 10 , further comprising a pressure sensor provided in a part of the grass clippings transport passage located between the shutter and an end part of the grass clippings transport passage adjacent to the grass clippings receptacle, the controller being configured to start the reciprocal opening and closing control in a case where the pressure is greater than a predetermined pressure determination value at a time after a predetermined transition period has elapsed from a start of driving of the work unit.