Engine-drive work machine

Abstract

An engine-driven work machine having a target engine speed selection unit and a control unit. The target engine speed selection unit selects and specifies an arbitrary target engine speed from among a plurality of target engine speeds that is set in stepwise fashion. The control unit electrically controls the opening and closing of a throttle valve so that the actual engine speed conforms to the specified target engine speed.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

Certain preferred embodiments of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which:

FIG. 1 is a left side elevational view of an engine-driven work machine according to a first embodiment of the present invention;

FIG. 2 is a schematic system diagram of the engine-driven work machine of FIG. 1;

FIG. 3 is a characteristic diagram of the engine of FIG. 2;

FIG. 4 is a perspective view of the area surrounding the rear portion of the handle of FIG. 1, as seen from the upper right;

FIG. 5 is a view of the area surrounding the left rear portion of the handle shown of FIG. 4, as seen from the direction of arrow 5;

FIG. 6 is a view of the area surrounding the left rear portion of the handle of FIG. 4, as seen from the direction of arrow 6;

FIG. 7 is a side view showing the relationship between the handle of FIG. 6 and the work clutch lever and work clutch operation detection sensor;

FIGS. 8A through 8C are views showing example operations of the work clutch lever and travel lever of FIGS. 6 and 7;

FIG. 9 is a flowchart showing the sequential procedure from the time of the startup operation of the engine of FIG. 2 until the control unit executes the control routine;

FIG. 10 is a detailed control flowchart of the execution of the steps of the engine speed control routine of FIG. 9;

FIG. 11 is a diagram showing the actions in the control flowchart of FIG. 10;

FIG. 12 is a side elevational view of an engine-driven work machine according to a second embodiment of the present invention;

FIG. 13 is a schematic system diagram of the engine-driven work machine shown in FIG. 12;

FIG. 14 is a partial cutaway view of the area surrounding the rear portion of the handle of FIG. 12, as seen from the left side;

FIG. 15 is a plan view showing the area surrounding the back portion of the handle of FIG. 14;

FIG. 16 is a side elevational view of an engine-driven work machine according to a third embodiment of the present invention;

FIG. 17 is a schematic system diagram of the engine-driven work machine of FIG. 16;

FIG. 18 is a diagram showing a conceptual control performed by the control unit shown in FIG. 17;

FIGS. 19A and 19B are control flowcharts of the control unit shown in FIG. 17;

FIG. 20 is a detailed control flowchart of the execution of the steps in the engine speed setting routine shown in FIGS. 19A and 19B;

FIG. 21 shows a target value increase correction map and a target value reduction correction map used in the control flowchart shown in FIG. 20;

FIG. 22 is a side elevational view of an engine-driven work machine according to a fourth embodiment of the present invention;

FIG. 23 is a schematic system diagram of the engine-driven work machine shown in FIG. 22;

FIG. 24 is a perspective view showing the area surrounding the rear portion of the handle shown in FIG. 22, as seen from the upper right;

FIG. 25 is an enlarged view of the area surrounding the left rear portion of the handle shown in FIG. 24;

FIG. 26 is a view showing the area surrounding the left rear portion of the handle shown in FIG. 25, as seen from the direction of arrow 26;

FIG. 27 is a perspective view showing a relationship between the handle of FIG. 25 and the engine speed changing switch and boost lever;

FIG. 28 is a is a side view showing the relationship between the handle shown in FIG. 27 and the engine speed changing switch and boost lever;

FIG. 29 is a view showing the area surrounding the left rear portion of the handle shown in FIG. 24, as seen from the direction of arrow 29;

FIG. 30 is a view showing the area surrounding the left rear portion of the handle of FIG. 24, as seen from the direction of arrow 30;

FIGS. 31A through 31D are views showing example operations of the work clutch lever, travel lever, and boost lever shown in FIGS. 24 and 27;

FIG. 32 is a flowchart of the control performed by the control unit shown in FIG. 23;

FIG. 33 is a detailed control flowchart of the execution of the steps in the engine speed temporary change routine shown in FIG. 32;

FIG. 34 is a diagram showing the actions in the control flowchart shown in FIG. 33;

FIG. 35 is a flowchart showing the control of a first modification of the control unit according to the fourth embodiment;

FIG. 36 is a diagram showing the actions performed in the control flowchart of FIG. 35;

FIG. 37 is a schematic system diagram of a second modification of the engine-driven work machine according to the fourth embodiment;

FIGS. 38A through 38C are flowcharts of the control performed by the control unit of FIG. 37;

FIGS. 39A through 39C are flowcharts showing the control of the control unit according to a third modification of the fourth embodiment;

FIG. 40 is a left side elevational view of an engine-driven work machine according to a fifth embodiment of the present invention;

FIG. 41 is a schematic system diagram of the engine-driven work machine shown in FIG. 40;

FIG. 42 is a perspective view showing the area surrounding the rear portion of the handle shown in FIG. 40, as seen from the upper right;

FIG. 43 is an enlarged view of the area surrounding the left rear portion of the handle of FIG. 42;

FIG. 44 is a view showing the area surrounding the left rear portion of the handle of FIG. 43, as seen from the direction of arrow 44;

FIG. 45 is a perspective view showing relationships among the handle of FIG. 44, the shift lever, switching lever, rotation mode switch, and linkage mechanism;

FIG. 46 is a perspective view showing relationships among the handle of FIG. 45, the shift lever, switching lever, rotation mode switch, and linkage mechanism;

FIG. 47 is a view showing the area surrounding the left rear portion of the handle shown in FIG. 42, as seen from the direction of the arrow 47;

FIG. 48 is a view showing the area surrounding the left rear portion of the handle shown in FIG. 42, as seen from the direction of arrow 48; and

FIGS. 49A through 49F are views showing example operations of the work clutch lever, travel lever, shift lever, and switching lever shown in FIGS. 44 through 46.

Claims

1. An engine-driven work machine for driving an implement by an engine, comprising: a target engine speed selection unit for selecting and specifying an arbitrary target engine speed from among a plurality of target engine speeds that is set in a stepwise fashion; anda control unit for electrically controlling opening and closing of a throttle valve of the engine so as to cause an actual engine speed of the engine to conform to the target engine speed specified by the target engine speed selection unit.

2. The work machine of claim 1, wherein the plurality of target engine speeds comprises two target engine speeds that include: a medium target engine speed at which the engine is substantially capable of generating a maximum torque; anda high target engine speed which is higher than the medium target engine speed and at which the engine is substantially capable of generating a maximum output.

3. The work machine of claim 1, further comprising: a clutch for disengaging and engaging an output that is transmitted from the engine to the implement;a work clutch operating unit for operating the clutch; anda work clutch operation detection sensor for detecting that the clutch has been placed in the engaging position by the work clutch operating unit.

4. The work machine of claim 3, wherein the control unit executes control on the basis of the specified target engine speed only when the work clutch operation detection sensor detects that the clutch has been placed in the engaging position.

5. The work machine of claim 2, wherein the control unit increases the specified target engine speed in stepwise fashion with increased angle of the throttle valve increases.

6. The work machine of claim 5, wherein the control unit performs a stepwise reduction so as to reduce the specified target engine speed by a prescribed value each time the throttle angle is reduced by a prescribed reduction amount when the throttle angle is reduced, and the prescribed reduction value of the throttle angle and a prescribed increment by which the target engine speed is reduced in stepwise fashion are both set to small step values.

7. The work machine of claim 5, wherein the control unit performs a stepwise increase so as to increase the specified target engine speed by a prescribed value each time the throttle angle is increased by a prescribed increase amount when the throttle angle is increased, and the prescribed increase value of the throttle angle and a prescribed increment by which the target engine speed is increased in stepwise fashion are both set to large increment values.

8. The work machine of claim 5, wherein the control unit performs a stepwise increase according to an increase characteristic whereby the specified target engine speed is increased by a prescribed value each time the throttle angle is increased by a prescribed increase amount when the throttle angle is increased; and performs a stepwise reduction according to a reduction characteristic whereby the specified target engine speed is reduced by a prescribed value each time the travel is reduced by a prescribed reduction amount when the throttle angle is reduced, and the increase characteristic and the reduction characteristic are hysteretic.

9. The work machine of claim 1, further comprising a target engine speed change operation unit for issuing a temporary change command on the basis of a human operation, wherein the control unit temporarily changes the specified target engine speed to another target engine speed according to the change command only when a condition wherein the engine-driven work machine is operating is satisfied.

10. The engine-driven work machine of claim 9, further comprising a travel unit capable of self-propulsion, wherein the control unit determines that a condition in which the engine-driven work machine is operating is satisfied when at least one condition is satisfied from the group consisting of a condition in which work is being performed by an implement, and a condition in which travel is being performed by the travel unit.

11. The work machine of claim 9, wherein the specified target engine speed is a medium target engine speed at which the engine is substantially capable of generating a maximum torque, and the other target engine speed is a high target engine speed which is higher than the medium target engine speed and at which the engine is substantially capable of generating a maximum output.

12. The work machine of claim 9, wherein the target engine speed change operation unit continuously issues the change command only during the time in which human operation is continued, and the control unit increases the specified target engine speed value according to a time during which the change command is issued, and uses the increased value as the other target engine speed.

13. The work machine of claim 1, further comprising: a machine body which has the travel unit and on which the engine is mounted;left and right handlebars that extend to the rear from the machine body; anda grip portion that extends between the rear ends of the left and right handlebars,wherein the grip portion comprises left and right grip leg portions that extend upward from rear ends of the left and right handlebars; and a grip bar that extends between upper ends of the left and right grip leg portions, and the target engine speed selection unit is provided to a rear end portion of a handlebar selected from the left and right handlebars.

14. The work machine of claim 13, further comprising a target engine speed change operation unit for temporarily changing the specified target engine speed, wherein the target engine speed change operation unit has an operating member for manual operation, and the operating member is provided in a position which is close to the target engine speed selection unit and where operation of the operating member by a hand gripping a handlebar selected from the left and right handlebars is permitted.

15. The work machine of claim 14, further comprising: a lever that is used for operating an element selected from the implement and the travel unit, and that is positioned so as to be generally parallel to a rear surface of the grip portion;left and right lever leg portions that are generally parallel to the left and right grip leg portions, respectively; anda horizontal bar extending between upper ends of the left and right lever leg portions and being generally parallel to the grip bar,wherein an interval between the left and right lever leg portions is set to be smaller than an interval between the left and right grip leg portions, whereby an operating space is provided between the grip leg and the lever leg portion on one of the left side and the right side, the operating member being disposed in the operating space.

16. The work machine of claim 15, wherein the operating member comprises an operating lever extending further to the rear than the grip portion.

17. The work machine of claim 1, further comprising: a machine body which has the travel unit and on which the engine is mounted;a handle extending to the rear from the machine body;a shift lever provided to the handle and used to adjust the travel speed of the travel unit; anda linkage mechanism for linking the shift lever to the operation of the target engine speed selection unit.

18. The work machine of claim 17, wherein the linkage mechanism switches the shift lever to a speed reduction side when the target engine speed selection unit is moved from a low-speed target engine speed to a high-speed target engine speed among the plurality of target engine speeds.

19. The work machine of claim 17, wherein the target engine speed selection unit comprises a switching lever provided to the handle, and a switch that can be operated by the switching lever, the linkage mechanism comprises an engaging portion provided to the switching lever, and an engagement-receiving portion provided to the shift lever, and the engaging portion engages with the engagement-receiving portion in conjunction with movement of the switching lever, whereby the shift lever is moved in conjunction with the switching lever.

20. The work machine of claim 19, wherein the switching lever comprises a grip, and the grip is disposed in a vicinity of a grip portion of the handle.