JP2007198245A - Engine driven work machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve operability of an engine driven work machine and improve work efficiency by enabling a worker to easily adjust rotation speed of an engine according to load of the engine. <P>SOLUTION: The engine driven work machine 10 electrically controls open and close of a throttle valve 92 to match actual rotation speed of an engine 14 driving a working part 15 to a target rotation speed. The engine driven working machine is provided with a target rotation speed change over operation part 60 issuing change over order to phasedly and temporarily change target rotation speed according to manual operation, and a control part 89 changing target rotation speed according to change over order of the target rotation speed change operation part and controlling open and close of the throttle valve to make actual rotation speed match to the changed target rotation speed only when a condition where the engine driven work machine is operating is satisfied. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an engine-driven work machine including various working units driven by an engine.

As a working machine provided with a working unit driven by an engine, for example, a walking lawn mower is known in which a grass cutter is mowed by a cutter while being self-propelled and an operator is maneuvering while walking. Further, in recent years, there is a model of a walking lawn mower that automatically controls a throttle valve with an electronic governor provided in an engine (see, for example, Patent Document 1).
JP 2005-98223 A

The walking-type lawn mower shown in Patent Document 1 mows the lawn while self-propelled by rotating the driving wheel and the lawnmower cutter by the output of the engine, and includes an electronic governor. This electronic governor controls the engine speed as follows by electrically controlling the opening and closing of the throttle valve.
(1) When the operator does not perform either the running operation of the walking lawn mower or the lawn mowing operation (the operation of rotating the lawn mowing cutter), the engine speed is set to the idling speed. Control to be
(2) When the operator performs only the traveling operation, control is performed so that the engine speed is gradually increased in order to prevent sudden start of the walking lawn mower.
(3) When an operator performs a lawn mowing operation, regardless of whether or not there is a traveling operation, the engine speed is increased to a certain speed at the time of mowing, and then the state is maintained. Control.

  By the way, working conditions when working with various engine-driven working machines as shown in Patent Document 1 are not necessarily constant. Depending on the working conditions, the load on the working unit may fluctuate greatly during the work. As a result, the load on the engine can also vary greatly.

  On the other hand, it is also conceivable that an operator adjusts the engine speed as appropriate by operating the throttle lever according to the engine load. When the load is small, the engine output is sufficient even when working with the engine speed reduced. Further, when the load is large, the work may be performed with the engine speed increased to increase the engine output.

  However, the adjustment operation is troublesome if the operator operates the throttle lever to adjust the engine speed to an appropriate value every time the engine load changes during the work. Also, if the engine speed is reduced too much, the engine output becomes too small to handle the load. As described above, a certain level of skill is required to appropriately adjust the rotational speed appropriately.

  In order to stop this troublesome and skillful adjustment operation, it is conceivable to keep the engine output large by always increasing the engine speed sufficiently regardless of the engine load. . However, the engine speed remains high even when the load is small. As a result, engine noise at a high rotation speed continues, which is disadvantageous in improving the working environment.

  According to the present invention, (1) by enabling the operator to easily adjust the engine speed according to the engine load, the operability of the engine-driven work machine is improved and the working efficiency is further improved. (2) It is an object of the present invention to provide a technique capable of reducing a noise generated by an engine-driven work machine and enhancing a work environment.

  In the invention according to claim 1, in the engine-driven work machine that electrically opens and closes the throttle valve so that the actual speed of the engine that drives the working unit matches the target speed, the engine-driven work machine includes: Satisfying the condition that the target rotational speed changing operation unit that issues a change command so as to change the target rotational speed stepwise and temporarily according to an artificial operation and the engine-driven work machine is in operation. A control unit that controls opening / closing of the throttle valve so that the actual rotational speed matches the changed target rotational speed while changing the target rotational speed in accordance with the change command of the target rotational speed changing operation section only when It is characterized by having.

  In the invention according to claim 2, in claim 1, when the control unit satisfies at least one of a condition that the working unit is operated and a condition that the engine-driven work machine is driven, It is configured to determine that a condition that the engine-driven work machine is in operation is satisfied.

  According to a third aspect of the present invention, in the first or second aspect, the target rotational speed that is changed stepwise by the change command of the target rotational speed changing operation unit is the rotational speed at which the engine can generate the maximum torque or There are two stages, a target medium speed rotation speed close to the rotation speed and a rotation speed at which the engine can generate the maximum output at a speed higher than the target medium speed rotation speed or a target high speed rotation speed close to the rotation speed. The unit is configured to change to a target medium speed rotation speed and a target high speed rotation speed in response to a change command from the target rotation speed change operation section.

  According to a fourth aspect of the present invention, in the first or second aspect, the target rotational speed changing operation unit is configured to issue a change command continuously only when being operated artificially, and the control unit includes: Further, the present invention is characterized in that the target rotational speed is increased in accordance with the time when the change command is issued.

  In the invention according to claim 1, only when the engine-driven work machine is in operation (for example, only during traveling or during work), the target engine speed is changed by manipulating the target engine speed changing operation unit. The throttle valve can be electrically opened and closed by the controller so that the actual rotational speed matches the changed target rotational speed in a stepwise and temporary manner. Therefore, the operator can change the target rotational speed to an arbitrary target rotational speed very simply by operating the target rotational speed changing operation unit to change the target rotational speed stepwise and temporarily. For this reason, the operator does not need to finely adjust the target rotational speed by operating the throttle lever.

  In this way, the load on the engine-driven work machine fluctuates greatly, so that even if the load on the engine fluctuates greatly, the operator can easily adjust the engine speed according to the engine load. can do. As a result, the operability of the engine-driven work machine can be improved and the work efficiency can be improved. Moreover, since the operator can arbitrarily and temporarily change the number of revolutions of the engine according to the work situation by the engine-driven work machine, the finish of the lawn after the mowing work, etc. The finish can be improved.

  Further, when the load is small, the engine noise can be reduced by simply operating the target rotation speed changing operation unit to lower the engine rotation speed. As a result, the noise generated by the engine-driven work machine can be reduced and the working environment can be enhanced. In addition, by reducing the engine speed when the load is small, the fuel consumption of the engine can be reduced, and dust generated by the engine-driven work machine can also be reduced.

  In the invention according to claim 2, when the working unit is operated or when the engine-driven work machine is run, the control unit determines that the engine-driven work machine is operating. The target rotational speed can be changed minutely in a stepwise manner in accordance with fluctuations in the work load of the working unit itself and fluctuations in the travel load of the engine-driven work machine. As a result, the working efficiency of the engine-driven work machine can be further increased.

In the invention according to claim 3, the value of the target rotational speed that is changed stepwise by the change command of the target rotational speed changing operation unit is set to the target medium speed rotational speed and the target high speed that is higher than the target medium speed rotational speed. This is set in two stages, the rotation speed.
It is known that a general engine characteristic is a characteristic that generates a maximum torque at a lower speed than a speed capable of generating a maximum output as the output increases as the speed increases. In the invention according to claim 3, the target medium speed rotation speed is set to a rotation speed at which the engine can generate the maximum torque or a value close to the rotation speed. The target high speed rotational speed is set to a rotational speed at which the engine can generate the maximum output or a value close to the rotational speed.

  When the engine load is small, the engine output is sufficient even if the work is performed with the engine speed reduced. Moreover, the working unit can be driven with a large torque by setting the value of the target rotational speed to the rotational speed at which the engine can generate the maximum torque or the target medium speed rotational speed close to the rotational speed. For this reason, it can fully cope with the fluctuation of the load on the working unit (there is a so-called stickiness). Further, by switching the value of the target rotational speed to the target medium speed rotational speed, the engine rotational speed can be lowered and the engine noise can be reduced.

On the other hand, when the engine load is large, the engine speed can be increased by switching the target speed value to the target high speed speed, and the work can be efficiently performed with the engine output increased.
As described above, when the engine load greatly fluctuates during the operation of the engine-driven work machine, the operator can easily set the engine speed in two stages of medium speed and high speed according to the load. Can do. Moreover, since the speed setting to be changed by the target rotation speed changing operation unit is only two stages, the changing operation can be performed very easily.

  In the invention which concerns on Claim 4, over the time which is operating the target rotation speed change operation part continuously, the target rotation speed change operation part is made to issue a change command continuously, and this change command is issued. Since the control unit increases the target rotational speed according to time, the target rotational speed can be set even more finely. As a result, the working efficiency of the engine-driven work machine can be further enhanced.

The best mode for carrying out the present invention will be described below with reference to the accompanying drawings. Note that “front”, “back”, “left”, and “right” follow the direction as viewed from the operator.
Hereinafter, in the present embodiment, a walking lawn mower will be described as an example of an engine-driven working machine. However, the engine-driven work machine is not limited to the walking lawn mower.

FIG. 1 is a left side view showing a walking lawnmower according to the present invention.
The walking lawnmower 10 includes left and right front wheels 12 and left and right rear wheels 13 (drive wheels 13) at front and rear ends of a housing 11 with an open bottom surface, and an engine 14 is mounted on the top of the housing 11. A cutter 15 is provided inside, a lawn accommodating bag 16 is provided at a cut grass discharge port 11 a of the housing 11, a handle 17 is extended rearward and upward from the housing 11, and an operation portion 18 is provided at a rear end portion of the handle 17. It is.

  As described above, the housing 11 is provided with the main members such as the front wheel 12, the rear wheel 13, the engine 14, and the like, and thus also serves as the body (frame) of the walking lawnmower 10. The lawn storage bag 16 is a container for storing the cut grass.

The engine 14 is a power source in which an output shaft 19 extends downward from a lower end portion, and a cutter 15 is attached to the lower end portion of the output shaft 19 via a work brake / clutch portion 21. The cutter 15 (cutting blade 15) is a working unit for performing lawn mowing work.
Further, the engine 14 is configured such that the output shaft 19 is connected to the input side of a hydraulic continuously variable transmission 25 (hereinafter simply referred to as “transmission 25”) via a transmission mechanism 22. The output shaft of the transmission 25 is connected to the rear wheel 13 via the axle 26.

  The work brake / clutch portion 21 is a clutch portion that cuts off / couples the output transmitted from the engine 14 to the cutter 15 and a brake that brakes the cutter 15 when the clutch is cut off (clutch off, output transmission cut off). It is a composite structure combining parts. Hereinafter, the work brake / clutch portion 21 is simply referred to as “clutch 21”.

The speed change device 25 includes a speed change swash plate (not shown) built in a case, a speed change arm 25a is connected to the speed change swash plate, and a speed change lever 62 is connected to the speed change arm 25a via a speed change cable 27. This is a known configuration.
That is, the transmission device 25 is a stepless transmission gear that changes the rotation speed of the rear wheel 13 from zero (stop) to a high-speed rotation range. Thus, the transmission 25 cuts off / couples the output transmitted from the engine 14 to the rear wheel 13 (that is, shuts off the rear wheel 13 by blocking and rotates the rear wheel 13 by connecting). Has a so-called clutch function.

Next, the area around the handle 17 will be described.
The handle 17 includes left and right handlebars 31 and 32 that extend rearward and upward from the housing 11 and a grip portion 33 that spans the left and right handlebars 31 and 32.
The left and right handlebars 31 and 32 are provided with left and right mounting brackets 38 and 39 at the rear end portions 31a and 32a, respectively, and the working clutch lever 41 and the traveling lever 42 can be swung back and forth in these mounting brackets 38 and 39. It is an installed configuration.

The work clutch lever 41 and the travel lever 42 can be swung forward by hand and grasped together with the grip 33, and automatically return to the original position when the operated hand is released. It is an operation member.
The left handle bar 31 is provided with the operation unit 18 and the cover 71 at the rear end 31a.

FIG. 2 is a schematic system diagram of the walking lawn mower according to the present invention.
First, the operation unit 18 will be described. The operation unit 18 includes a target rotation speed change operation unit 60, a transmission lever 62, a main switch 64, a rotation mode changeover switch 65, and a work clutch operation detection sensor 68.

The speed change lever 62 is used to change the speed of the speed change device 25 and is connected to the travel lever 42 via the second tension spring 106 and connected to the speed change device 25 via the speed change cable 27.
When the traveling lever 42 is operated, the transmission 25 rotates the rear wheel 13 at a speed corresponding to the transmission operation position of the transmission lever 62. Thereafter, when the traveling lever 42 is returned to the original position, the output rotation of the transmission 25 becomes zero, and the rear wheel 13 is stopped.

  The main switch 64 is a rotary switch for turning on and off the power supply system of the engine 14, and is prepared for starting the engine 14 by operating from the off position to the on position, and returning from the on position to the off position. 14 can be stopped.

  The rotation mode changeover switch 65 is a target rotation speed switching operation for instructing a value of one target rotation speed that is arbitrarily selected from preset values of the target rotation speed of the engine 14 at a plurality of stages. Part 65 (target rotational speed selection part). More specifically, the rotation mode switch 65 switches the control mode of the engine 14 between a “silent mode” and a “power mode”, which will be described later. For example, a seesaw switch (“tumbler switch”, “rocker switch” "Also.)

The target rotational speed changing operation unit 60 (the rotational speed changing unit 60) issues a change command so as to change the target rotational speed of the engine 14 stepwise and temporarily according to an artificial operation. It consists of a number change switch 66 and a boost lever 67.
The boost lever 67 is an automatic return type operating member that automatically returns to its original position when the operating hand is released from the lever. The rotation speed change switch 66 performs a switch operation according to the operation of the boost lever 67. For example, the rotation speed change switch 66 is turned on when the boost lever 67 is operated, and turned off when the boost lever 67 is returned to its original position.

  The work clutch operation detection sensor 68 detects that the clutch 21 has been engaged by the work clutch lever 41 (that is, the work clutch operation unit 41), and is composed of, for example, a switch. When the working clutch lever 41 is operated and the clutch 21 is coupled (clutch on) via the clutch cable 122, the working clutch operation detection sensor 68 detects that the coupling operation has been performed.

Next, the system of the engine 14 will be described.
The engine 14 includes a recoil starter 81, an ignition device 82, a throttle valve control motor 83, a motor driver 84, a throttle opening sensor 85, an engine rotation sensor 86, a generator 87, a power supply circuit 88, and a control unit 89. The engine 14 does not include a battery.

  The recoil starter 81 is a starting device that allows an operator to start the engine 14 manually. For example, the recoil starter 81 is provided at the tip of the flywheel of the engine 14. The ignition device 82 includes an ignition coil and a spark plug (not shown).

  A throttle valve control motor 83 (hereinafter, referred to as “control motor 83”) is an actuator that opens and closes a throttle valve 92 provided in the engine intake system 91, and includes, for example, a step motor. The motor driver 84 electrically drives the control motor 83 on and off based on a control signal from the control unit 89.

The throttle opening sensor 85 detects the opening of the throttle valve 92 and issues a detection signal to the control unit 89. The engine rotation sensor 86 detects the rotation speed (rotation speed) of the engine 14 and issues a detection signal to the control unit 89.
The generator 87 is an alternator that generates AC power using part of the output of the engine 14, and is provided, for example, on a flywheel. The power supply circuit 88 rectifies the AC power generated by the generator 87 and converts it into DC power, and then supplies it to electrical components such as the ignition device 82 and the control unit 89.

  The control unit 89 receives signals from the main switch 64, the rotation mode changeover switch 65, the rotation speed change switch 66 of the target rotation speed change operation part 60, the working clutch operation detection sensor 68, the throttle opening sensor 85, and the engine rotation sensor 86. In response to this, it is an electronic control unit that controls the engine 14 in a predetermined control mode, and comprises, for example, a microcomputer. That is, the control unit 89 controls the ignition device 82, and further, based on the detected data of the rotational speed of the engine 14 and the opening degree of the throttle valve 92, the throttle valve 92 via the control motor 83 in a predetermined control mode. By controlling the opening degree, the engine 14 is electrically controlled so that the rotational speed of the engine 14 matches the target rotational speed.

  As is clear from the above description, the engine 14 is characterized by mounting an electronic governor 80 (also referred to as an electric governor or electronic governor). The electronic governor 80 controls the rotational speed of the engine 14 by automatically adjusting the opening of the throttle valve 92 by the control motor 83 based on the control signal of the control unit 89. 83, a motor driver 84, a throttle opening sensor 85, an engine rotation sensor 86, a control unit 89, and a throttle valve 92.

By the way, the control mode in which the control unit 89 controls the rotation speed of the engine 14 is roughly divided into three rotation control modes. These rotation control modes are defined as follows.
The first rotation control mode is an “idle mode” for controlling the engine speed in an idling state. The second rotation control mode is a “silent mode” in which the engine speed is controlled when the torque generated by the engine 14 is maximum or substantially maximum. The third rotation control mode is a “power mode” in which the engine speed is controlled so that the output generated by the engine 14 is maximum or substantially maximum.

Hereinafter, the engine speed when the torque generated by the engine 14 is maximum or substantially maximum is referred to as “target medium speed NM”. In addition, an engine speed that is higher than the target medium speed NM and is capable of generating the maximum output by the engine 14 or a value close to the engine speed is referred to as a “target high speed NH”. To do.
It is known that the general characteristics of the engine 14 are characteristics in which the output increases as the rotational speed increases and the maximum torque is generated at a lower rotational speed than the rotational speed capable of generating the maximum output. .

Next, the detailed configuration of each member around the handle 17 and the operation unit 18 will be described.
FIG. 3 is a perspective view of the vicinity of the rear portion of the handle of the walking lawn mower according to the present invention as viewed from the upper right front, and shows a state in which the working clutch lever 41 and the traveling lever 42 are gripped.
4 is a view taken in the direction of arrow 4 in FIG. 3 and shows a state in which the working clutch lever 41 and the traveling lever 42 are gripped.
FIG. 5 is a view taken in the direction of arrow 5 in FIG. 3 and shows a state in which the hand is released from the working clutch lever 41 and the traveling lever 42.

  As shown in FIG. 3, the frontal portal grip 33 includes left and right grip legs 34 and 35 extending frontward and upward from the rear ends 31 a and 32 a of the left and right handlebars 31 and 32, and left and right grips. A grip horizontal bar 36 is provided between the upper ends of the legs 34 and 35.

As shown in FIGS. 3 to 5, the working clutch lever 41 is an operation member having a front portal shape so as to substantially follow the rear surface of the grip portion 33, and includes left and right leg portions 44 and 45 and a horizontal bar 46. It consists of.
As shown in FIG. 5, the working clutch lever 41 includes an unlocking knob 113 for performing a push-down operation, an operating rod 114 that descends in conjunction with the lowering of the unlocking knob 113, and an interlocking operation with the operating rod 114. An engagement member 115 that swings backward, a clutch arm 121 that engages with the swinging engagement member 115, and a clutch cable 122 that has one end connected to the clutch arm 121 are provided.

  The clutch cable 122 can be pulled backward by swinging the working clutch lever 41 forward while pressing the unlocking knob 113. As a result, the clutch 21 (see FIG. 1) is engaged.

  As shown in FIGS. 3 to 5, the traveling lever 42 is an operation member having a front portal shape so as to substantially follow the rear surface of the working clutch lever 41, and includes left and right leg portions 52 and 54 and a horizontal bar 55. It consists of.

As shown in FIG. 3, the left leg 52 of the travel lever 42 is located closer to the center of the body width than the left leg 44 of the working clutch lever 41. For this reason, when the working clutch lever 41 and the traveling lever 42 are overlapped with the grip portion 33, an operation space 56 having a distance SP is provided between the left leg portions 44 and 52. The operator can grasp the left grip leg 34 and the left leg 44 of the work clutch lever 41 together with the left hand 57 in the operation space 56.
On the other hand, the operator can hold the grip horizontal bar 36, the horizontal bar 46 of the working clutch lever 41, and the horizontal bar 55 of the traveling lever 42 together with the right hand 58.

As shown in FIGS. 3 and 5, the speed change lever 62 includes a generally disk-shaped disc portion 94 and an operation lever portion 95 extending upward from the disc portion 94.
The disk portion 94 is configured to be swingable back and forth to the left handlebar 31 via a support pin 96 with the shift lever arm 63 superimposed on the side portion. The transmission lever arm 63 is an elongated member extending downward, and can swing back and forth relative to the disk portion 94.

  As shown in FIG. 5, the disk portion 94 has a first guide hole 98 having an elongated curved shape centering on the support pin 96. The first guide hole 98 is formed so that the radius is R1 at the rear end and the diameter R2 at the front end. When the radius R1 of the rear end portion and the radius R2 of the front end portion are compared, the relationship of R1 <R2 is established. That is, the radius of the first guide hole 98 is formed so as to gradually increase from the rear end portion toward the front end portion.

The transmission lever arm 63 has a second guide hole 99 elongated in the vertical direction substantially orthogonal to the first guide hole 98.
The transmission cable 27 is obtained by fitting a connecting pin 101 provided at one end of the inner cable 27 a into the first guide hole 98 and the second guide hole 99.

As shown in FIGS. 3 and 5, the front end portion of the speed change lever arm 63 hooks the first tension spring 103 on the support arm 102 disposed in front of the speed change lever arm 63, and moreover than the speed change lever arm 63. This is a configuration in which a traveling arm 105 disposed rearward is connected via a second tension spring 106.
The support arm 102 is a fixing member provided in the left handle bar 31. The first tension spring 103 is a return spring for automatically returning the shift lever arm 63 to the travel stop position shown in FIGS. 3 and 5. The traveling arm 105 is a swing member provided in the traveling lever 42 and can swing back and forth together with the traveling lever 42.

  As shown in FIGS. 3 to 5, the boost lever 67 is disposed in the vicinity of the rear end portion 31 a of the left handlebar 31 and in the vicinity of the left grip leg portion 34. More specifically, the boost lever 67 includes an arm portion 126 attached to the left handlebar 31 via a support pin 125 so as to be swingable back and forth, and an operation lever portion 127 extending rearward and upward from the arm portion 126. Become. The operation lever portion 127 has a grip 127a at the tip.

  As shown in FIGS. 3 and 5, the tip of the grip 127 a is located slightly behind the left grip leg 34. Therefore, the operator can operate the boost lever 67 by pushing the grip 127a forward with the thumb 57a while holding the left grip leg 34 with the left hand 57 at the position of the operation space 56. As a result, the rotation speed change switch 66 is turned on.

  3 and 4, the operation unit 18 has a main switch 64 disposed on the left front side of the boost lever 67, a rotation mode switching switch 65 disposed on the right side of the main switch 64, and the main switch 64. A shift lever 62 is arranged on the right front side of the rotation mode changeover switch 65 and on the left front side.

  The rotation mode switch 65 generates an off signal (“power mode” switching signal) in a state in which the front portion 65b of the operation knob 65a is pushed in, and an on signal (“” in the state in which the rear portion 65c of the operation knob 65a is pushed in. Silent mode "switching signal).

  The cover 71 has an upper surface 72, a transmission lever hole 73 through which the operation lever portion 95 of the transmission lever 62 passes, a main switch hole 74 through which the operation knob 64 a of the main switch 64 passes, and an operation knob 65 a of the rotation mode changeover switch 65. It has a selector switch mounting hole 75 that passes therethrough and a boost lever hole 76 through which the operation lever portion 127 of the boost lever 67 passes.

  Next, a control flow when the control unit 89 shown in FIG. 2 is a microcomputer will be described with reference to FIGS. In the figure, STxx indicates a step number. Step numbers that are not specifically described proceed in numerical order. Hereinafter, a description will be given with reference to FIGS. 2 and 3.

FIG. 6 is a flowchart showing a series of procedures from the starting operation time point of the engine according to the present invention until the control unit executes the control process.
ST01: The operator turns on the main switch 64.
ST02: When the main switch 64 is on, the operator pulls the knob 81a of the recoil starter 81 to start the recoil starter 81.
ST03: The engine 14 is started by the start operation of the recoil starter 81.
ST04: With the start of the engine 14, the generator 87 starts power generation.
ST05: The control unit 89 is automatically activated by the electric power supplied from the generator 87 when the output voltage of the generator 87 becomes a stable voltage of a certain level or higher.
ST06: The control unit 89 executes an initial setting process before starting predetermined control.
ST07: From this time point, the control unit 89 automatically executes the engine speed control process. A specific control flow for specifically executing this engine speed control process is shown in FIG.

  FIG. 7 is a control flowchart (main routine) of the control unit according to the present invention. A basic control flow for the control unit 89 to execute the “engine speed control process” of step ST07 shown in FIG. 6 is shown. Show.

ST11: Read the switch signal of each switch. Specifically, the signals of the rotation mode changeover switch 65, the rotation speed change switch 66, and the work clutch operation detection sensor 68 are read.
ST12: It is checked whether or not the working clutch lever 41 is in the off position. If YES, it is determined that the engine is in the “idle mode”, and the process proceeds to ST13. If NO, the process proceeds to ST14. As shown in FIG. 5, the position when the worker releases his / her hand from the work clutch lever 41 is the off position. The position of the working clutch lever 41 is determined by the detection signal of the working clutch operation detection sensor 68 (see FIG. 2).

ST13: Since the rotational control mode of the engine 14 has shifted to the “idle mode”, the target rotational speed Nt of the engine 14 is set to the value of the target low speed rotational speed NL. The target low speed NL is a constant speed set in advance, and corresponds to the idling speed of the engine 14.
ST14: It is checked whether or not the rotation control mode of the engine 14 is the “silent mode”. If YES, the process proceeds to ST15, and if NO, it is determined to be the “power mode” and the process proceeds to ST16. In ST14, the determination is YES when the rotation mode switch 65 is on, and the determination is NO when the rotation mode switch 65 is off.

ST15: Since the rotational control mode of the engine 14 has shifted to the “silent mode”, the target rotational speed Nt of the engine 14 is set to the value of the target medium speed rotational speed NM. The target medium speed rotation speed NM is a predetermined fixed rotation speed, and corresponds to the engine rotation speed when the torque generated by the engine 14 is maximum or substantially maximum.
ST16: Since the rotation control mode of the engine 14 has shifted to the “power mode”, the target engine speed Nt of the engine 14 is set to the value of the target high speed engine speed NH. The target high-speed rotation speed NH is a constant rotation speed set in advance, and corresponds to the engine rotation speed when the output generated by the engine 14 is maximum or substantially maximum.

  Here, the target medium speed rotation speed NM is larger than the target low speed rotation speed NL, and the target high speed rotation speed NH is larger than the target medium speed rotation speed NM (NL <NM <NH).

ST17: A process for temporarily changing the rotational speed of the engine 14 is executed. A subroutine for specifically executing ST17 is shown in FIG.
ST18: The actual rotational speed Nr of the engine 14 (hereinafter referred to as “actual rotational speed Nr”) is measured. The actual rotation speed Nr may be measured by the engine rotation sensor 86.
ST19: It is checked whether or not the actual rotational speed Nr is lower than the target rotational speed Nt. If YES, the process proceeds to ST20, and if NO, the process proceeds to ST21.

ST20: The throttle valve 92 is opened by driving the control motor 83 in the normal direction. As a result, the actual rotational speed Nr increases.
ST21: By driving the control motor 83 in the reverse direction, the throttle valve 92 is driven to close. As a result, the actual rotational speed Nr decreases.
ST22: The switch signal of the main switch 64 is read.
ST23: It is checked whether or not the main switch 64 is on. If YES, it is determined that the operation of the engine 14 is continued, and the process returns to ST11. If NO, it is determined that there is a stop command for the engine 14 and the process proceeds to ST24.
ST24: After stopping the engine 14, the control by this control flow is finished.

  FIG. 8 is a control flowchart (subroutine) of the control unit according to the present invention, and shows a subroutine for executing the temporary change process of the rotational speed of the engine 14 shown in step ST17 of FIG.

  ST101: It is checked whether or not the working clutch lever 41 is in the ON position. If YES, the process proceeds to ST102, and if NO, it is determined that the rotation control mode of the engine 14 is “idle mode” and the process returns to ST17 shown in FIG. . As shown in FIG. 3, the position where the operator swings the working clutch lever 41 forward is the on position. The position of the working clutch lever 41 is determined by the detection signal of the working clutch operation detection sensor 68 (see FIG. 2).

  ST102: It is checked whether or not the rotation control mode of the engine 14 is the “silent mode”. If YES, the process proceeds to ST103, and if NO, it is determined to be the “power mode” and the process returns to ST17 shown in FIG. In ST102, the determination is YES when the rotation mode changeover switch 65 is on, and the determination is NO when the rotation mode changeover switch 65 is off.

ST103: Since it has shifted to the “silent mode”, it is checked whether or not the rotation speed change switch 66 is on. If YES, it is determined that the “power mode” has been temporarily entered, and the process proceeds to ST104. Return to ST17 shown in FIG. The rotation speed change switch 66 is turned on only when the boost lever 67 is swung forward.
ST104: After setting the target engine speed Nt of the engine 14 to the value of the target high speed engine speed NH, the process returns to ST17 shown in FIG.

Next, the operation of the walking lawnmower 10 (engine-driven work machine 10) described in the control flowcharts of FIGS. 7 and 8 will be described based on FIG. 9 with reference to FIG.
FIG. 9 is an operation explanatory view of the walking lawn mower according to the present invention, and shows the operation of each part in a time chart with the horizontal axis as time.

  When the working clutch lever 41 is in the OFF position, the rotation control mode of the engine 14 is the “idle mode” regardless of the operation of the rotation mode changeover switch 65 and the rotation speed change switch 66 (ST12 in FIG. 7). For this reason, the target rotational speed Nt of the engine 14 maintains the value of the target low speed rotational speed NL (ST13 in FIG. 7).

  If the working clutch lever 41 is operated to the on position at the time t1 while the rotation mode changeover switch 65 is in the on state, the rotation control mode of the engine 14 is changed to the “silent mode” (ST12 and ST14 in FIG. 7). Therefore, the target engine speed Nt of the engine 14 changes to the value of the target medium speed engine speed NM (ST15 in FIG. 7).

Thereafter, when the rotation speed change switch 66 is turned on at time t2, that is, when the boost lever 67 is swung forward, the rotation control mode of the engine 14 is changed to the “power mode” (ST103 in FIG. 8). Therefore, the target engine speed Nt of the engine 14 changes to the value of the target high speed engine speed NH (ST104 in FIG. 8). This “power mode” state continues for a time during which the boost lever 67 is operated, for example, from time t2 to time t3.
Thus, only when the condition that the rotation control mode of the engine 14 is the “silent mode” is satisfied, the mode changes to the “power mode” over the time during which the boost lever 67 is operated.

  When the operation of the boost lever 67 is stopped at time t3, the original “silent mode” is restored. (ST103 in FIG. 8, ST14 in FIG. 7) Therefore, the target engine speed Nt of the engine 14 changes to the value of the target medium speed engine speed NM (ST15 in FIG. 7).

  Thereafter, when the rotation mode changeover switch 65 is turned off at time t4, the rotation control mode of the engine 14 is changed to the “power mode” (ST14 in FIG. 7, ST102 in FIG. 8). For this reason, the target engine speed Nt of the engine 14 changes to the value of the target high speed engine speed NH (ST16 in FIG. 7). In the “power mode” state, the “power mode” state is maintained regardless of the operating state of the rotation speed change switch 66, that is, the operation state of the boost lever 67. The target rotational speed Nt of the engine 14 also maintains the target high speed rotational speed NH.

  Thereafter, when the working clutch lever 41 is operated to the OFF position at time t5, the rotation control mode of the engine 14 is changed to the “idle mode” (ST12 in FIG. 7 and ST101 in FIG. 8). For this reason, the target rotational speed Nt of the engine 14 changes to the value of the target low speed rotational speed NL (ST13 in FIG. 7).

The above description is summarized as follows.
The control unit 89 changes the target rotational speed Nt in accordance with a change command from the target rotational speed changing operation unit 60 only when the condition that the engine-driven work machine 10 is operating is changed. The throttle valve 85 is controlled to be opened and closed so that the actual rotational speed Nr matches the target rotational speed Nt.

  In the present invention, only when the walking lawnmower 10 is in operation (for example, only during traveling or during work), the target rotational speed changing operation unit 60 is artificially operated to set the target rotational speed Nt of the engine 14 in a stepwise manner. The throttle valve 92 can be electrically opened and closed by the control unit 89 so that the actual rotational speed Nr matches the changed target rotational speed Nt. Therefore, the operator can change the target rotational speed Nt to any desired rotational speed Nt very simply by operating the target rotational speed changing operation unit 60 and changing the target rotational speed Nt stepwise and temporarily. For this reason, the operator does not have to perform a delicate adjustment of the target rotational speed Nt by operating the throttle lever.

Thus, even if the load applied to the engine 14 varies greatly due to a large change in the load of the walking lawn mower 10, the operator can change the target rotational speed of the engine 14 according to the load of the engine 14. Nt can be easily adjusted. As a result, the operability of the walking lawn mower 10 can be improved and the work efficiency can be increased.
In addition, since the operator can arbitrarily and temporarily change the target rotational speed Nt of the engine 14 according to the work situation by the walking lawn mower 10, various kinds of characteristics such as the finish of the lawn after the lawn mowing work, etc. The finish after work can be improved.

  Furthermore, when the load is small, the engine noise can be reduced by operating the target speed changing operation unit 60 simply and reducing the target speed Nt (actual speed Nr) of the engine 14. As a result, the noise generated by the walking lawnmower 10 can be reduced and the working environment can be increased. Moreover, by reducing the actual rotational speed Nr of the engine 14 when the load is small, the fuel consumption of the engine 14 can be reduced, and dust generated by the walking lawnmower 10 can also be reduced.

Furthermore, in the present invention, the target rotational speed Nt that is changed stepwise by the change command of the target rotational speed changing operation unit 60 is set to a target medium speed rotational speed NM and a target that is faster than the target medium speed rotational speed NM. This is set in two stages with the high speed rotation speed NH.
It is known that the general characteristics of the engine 14 are characteristics in which the output increases as the rotational speed increases and the maximum torque is generated at a lower rotational speed than the rotational speed capable of generating the maximum output. . In the present invention, the target medium speed rotation speed NM is set to a rotation speed at which the engine 14 can generate the maximum torque or a value close to the rotation speed. The target high speed rotational speed NH is set to a rotational speed at which the engine 14 can generate the maximum output or a value close to the rotational speed.

When the load on the engine 14 is small, the engine output is sufficient even if the work is performed with the actual rotational speed Nr of the engine 14 lowered. Moreover, the working unit 15 can be driven with a large torque by setting the value of the target rotational speed Nt to the rotational speed at which the engine 14 can generate the maximum torque or the target medium speed rotational speed NM close to the rotational speed. it can. For this reason, it is possible to sufficiently cope with fluctuations in the load of the working unit 15 (there is so-called stickiness).
Furthermore, by switching the value of the target rotational speed Nt to the target medium speed rotational speed NM, the actual rotational speed Nr can be lowered and the engine noise can be reduced.

  On the other hand, when the load of the engine 14 is large (for example, when mowing long lawn grass in the lawn mower 10), the actual rotational speed is switched by switching the target rotational speed Nt to the target high speed rotational speed NH. The work can be efficiently performed with Nr increased and the engine output increased.

  As described above, when the load greatly fluctuates during the operation of the walking lawn mower 10, the operator simply sets the target rotational speed Nt of the engine 14 in two stages of medium speed and high speed according to the load. be able to. In addition, since the speed setting to be changed by the target rotation speed changing operation unit 60 is only two steps, the changing operation can be performed very easily.

By the way, even when the target rotational speed switching operation section 65 (rotation mode switching switch 65) is operated, the same operation and effect as when the target rotational speed changing operation section 60 is operated are obtained.
When working in a “silent mode” or “power mode” for a relatively long time, it is preferable to switch the target rotational speed switching operation unit 65 as appropriate to keep the rotational control mode constant.
On the other hand, when working in the “silent mode”, only when the load temporarily increases, temporarily switch to the “power mode” to work, and quickly return to the original “silent mode”. When the operation is continued, it is preferable to switch the target rotation speed changing operation unit 60 as appropriate.
In this manner, the target rotation speed switching operation unit 65 and the target rotation speed changing operation unit 60 can be selected in accordance with the work situation, and the rotation control mode can be changed. As a result, the operability of the engine-driven work machine 10 can be further improved and the work efficiency can be further improved.

Next, a modification of the process for temporarily changing the rotational speed of the engine 14 shown in FIG. 8 will be described with reference to FIG.
FIG. 10 is a control flowchart (subroutine) of a modified example of the control unit according to the present invention. The modified subroutine for executing the temporary change process of the rotational speed of the engine 14 shown in step ST17 of FIG. Indicates.

ST201: It is checked whether or not the working clutch lever 41 is in the ON position. If YES, the process proceeds to ST202, and if NO, it is determined that the rotation control mode of the engine 14 is the “idle mode” and the process proceeds to ST213.
ST202: It is checked whether or not the rotation control mode of the engine 14 is the “silent mode”. If YES, the process proceeds to ST203, and if NO, it is determined to be the “power mode” and the process proceeds to ST211. In ST202, the determination is YES when the rotation mode changeover switch 65 is on, and the determination is NO when the rotation mode changeover switch 65 is off.

ST203: Since it has shifted to the “silent mode”, it is checked whether or not the rotation speed change switch 66 is ON. If YES, it is determined that the power mode operation has been temporarily performed, and the process proceeds to ST204. If NO, the process proceeds to ST207. move on. The rotation speed change switch 66 is turned on only when the boost lever 67 is swung forward.
ST204: The time Tc during which the rotation speed change switch 66 is on, that is, the elapsed time Tc, is counted by the timer built in the control unit 89. Note that the value of the elapsed time Tc when the count is started, that is, the initial value is 0.

  ST205: Check whether or not the elapsed time Tc has passed a predetermined reference time Ts (Tc ≧ Ts). If YES, the process proceeds to ST206, and if NO, the process proceeds to ST208. Here, the reference time Ts is a reference time for determining that the operator has operated the boost lever 67 with the intention of temporarily operating the power mode.

  ST206: Since there was a temporary power mode operation, the rotation speed Nu of the engine 14 to be increased according to the time Tc (elapsed time Tc) during which the operator temporarily operates the boost lever 67, that is, the increased rotation speed. Find Nu. The increased rotational speed Nu is calculated by multiplying the elapsed time Tc by the rotational speed increase rate ΔN (Nu = Tc × ΔN). Here, the rotational speed increase rate ΔN is the rotational speed of the engine 14 to be increased per unit time, and is a preset value.

  ST207: Since the temporary power mode operation of the boost lever 67 is not performed or has disappeared in ST203, the value of the increased rotation speed Nu obtained immediately before in ST206 is stored in the memory built in the control unit 89. To do.

  ST208: The target engine speed Nt of the engine 14 is obtained by adding the increased engine speed Nu due to the temporary power mode operation to the target medium speed engine speed NM in the silent mode (Nt = NM + Nu). Here, the increased rotation speed Nu is the value obtained in ST206 or ST207.

ST209: It is checked whether or not the target rotational speed Nt exceeds the target high speed rotational speed NH (Nt> NH). If YES, it is determined that the target rotational speed Nt is excessive, and the process proceeds to ST210. If NO, the target rotational speed Nt is It judges that it is appropriate and returns to ST17 shown in FIG.
ST210: After resetting the excessive target rotational speed Nt to the upper limit target high speed rotational speed NH, the process returns to ST17 shown in FIG.

ST211: Since the rotation control mode of the engine 14 is “power mode”, the target rotational speed Nt of the engine 14 is set to the value of the target high speed rotational speed NH.
ST212: After resetting the increased rotational speed Nu to a value of 0, the process returns to ST17 shown in FIG.
ST213: Since the rotation control mode of the engine 14 is the “idle mode”, the target rotational speed Nt of the engine 14 is set to the value of the target low speed rotational speed NL.
ST214: Increase rotation speed Nu is reset to 0.
ST215: After the elapsed time Tc counted by the timer is reset to 0, the process returns to ST17 shown in FIG.

Next, the operation of the engine-driven work machine 10 described in the control flowchart of the modification of FIG. 10 will be described based on FIG. 11 with reference to FIG.
FIG. 11 is an operation explanatory diagram of a modified example of the engine-driven working machine according to the present invention, and shows the operation of each part in a time chart with the horizontal axis as time.

  When the working clutch lever 41 is in the OFF position, the rotation control mode of the engine 14 is the “idle mode” regardless of the operation of the rotation mode changeover switch 65 or the rotation speed change switch 66 (ST12 in FIG. 7, FIG. 10). ST201). For this reason, the target rotational speed Nt of the engine 14 maintains the value of the target low-speed rotational speed NL (ST13 in FIG. 7 and ST213 in FIG. 10).

  If the working clutch lever 41 is operated to the ON position at the time t11 when the rotation mode changeover switch 65 is in the ON state, the rotation control mode of the engine 14 is changed to the “silent mode” (ST12 and ST14 in FIG. 7). Therefore, the target engine speed Nt of the engine 14 changes to the value of the target medium speed engine speed NM (ST15 in FIG. 7).

After that, when the rotation speed change switch 66 is turned on over the elapsed time Tc from time t12 to time t13, that is, when the boost lever 67 is swung forward, the increased rotation speed Nu is increased at a constant rate according to the elapsed time Tc. It gradually increases (ST203 to ST206 in FIG. 10). As the increased engine speed Nu increases, the target engine speed Nt of the engine 14 gradually increases from the value of the target medium speed engine speed NM at a constant increase rate (ST208 in FIG. 10).
Thus, the target rotational speed Nt of the engine 14 can be increased over the time during which the boost lever 67 is operated as long as the condition that the rotational control mode of the engine 14 is the “silent mode” is satisfied.

  When the operation of the boost lever 67 is stopped at time t13, the increased rotation speed Nu holds the value at this time t13 (ST207 in FIG. 10). For this reason, the target rotational speed Nt of the engine 14 also holds the value at the time point t13 (ST208 in FIG. 10).

Thereafter, when the rotation mode changeover switch 65 is turned off at time t14, the rotation control mode of the engine 14 is changed to “power mode” (ST14 in FIG. 7, ST202 in FIG. 10). Therefore, the target rotational speed Nt of the engine 14 changes to the value of the target high speed rotational speed NH (ST16 in FIG. 7 and ST211 in FIG. 10). In the “power mode” state, the “power mode” state is maintained regardless of the operating state of the rotation speed change switch 66, that is, the operation state of the boost lever 67.
In the “power mode” state, the increased rotation speed Nu is reset to 0 (ST212 in FIG. 10).

  When the rotation mode changeover switch 65 is turned on again at time t15, the rotation control mode of the engine 14 is changed to the “silent mode” (ST14 in FIG. 7). Therefore, the target engine speed Nt of the engine 14 changes to the value of the target medium speed engine speed NM (ST15 in FIG. 7).

  After that, when the rotation speed change switch 66 is turned on over the elapsed time Tc from time t16 to time t17, that is, when the boost lever 67 is swung forward, the increased rotation speed Nu is increased at a constant rate according to the elapsed time Tc. It gradually increases (ST203 to ST206 in FIG. 10). As the increased engine speed Nu increases, the target engine speed Nt of the engine 14 gradually increases from the value of the target medium speed engine speed NM at a constant increase rate (ST208 in FIG. 10).

However, when the target rotational speed Nt exceeds the target high speed rotational speed NH (Nt> NH), that is, when the increased rotational speed Nu is excessive, the value of the target rotational speed Nt is the value of the target high speed rotational speed NH. The upper limit is set (ST209 to ST210 in FIG. 10).
When the operation of the boost lever 67 is stopped at time t17, the increased rotation speed Nu holds the value at this time t17 (ST207 in FIG. 10). For this reason, the target rotational speed Nt of the engine 14 also holds the value at the time point t17 (ST208 in FIG. 10).

Thereafter, when the working clutch lever 41 is operated to the off position at time t18, the rotation control mode of the engine 14 is changed to the “idle mode” (ST201 in FIG. 10, ST12 in FIG. 7). Therefore, the target engine speed Nt of the engine 14 is changed to the value of the target low speed engine speed NL (ST213 in FIG. 10).
In the state where the working clutch lever 41 is in the off position, the increased rotational speed Nu and the elapsed time Tc are reset to 0 (ST214 to ST215 in FIG. 10).

According to the modification of the invention shown in FIGS. 10 to 11, in addition to the action in the invention shown in FIGS.
That is, the target rotation speed changing operation unit 60 of the modification is configured to issue a change command continuously only when it is manually operated, and the control unit 89 of the modification has a change command issued. The present invention is characterized in that the target rotational speed Nt is increased in accordance with the time Tc.

  In the invention of the modified example, the target rotation speed change operation unit 60 continuously issues a change command over the time Tc during which the target rotation speed change operation unit 60 is continuously operated, and this change command is issued. Since the control unit 89 increases the target rotational speed Nt according to the time Tc (that is, the elapsed time Tc), the target rotational speed Nt can be set even more finely. As a result, the working efficiency of the walking lawnmower 10 can be further increased.

  In the above-described embodiment and modification of the present invention, the control unit 89 causes the cutter 15 (working unit 15) to operate and the walking lawnmower 10 (engine-driven working machine 10) to travel. What is necessary is just to comprise so that it may be judged that the conditions that the walk-type lawn mower 10 is operating are satisfied when at least one of the conditions is satisfied.

  For example, the control unit 89 described with reference to FIGS. 1 to 11 includes ST12 in FIG. 7, ST101 in FIG. 8, and ST201 in FIG. 10, so that “the working clutch lever 41 is in the on position (that is, the cutter It is determined that the condition that the walking lawn mower 10 is in operation is satisfied when the condition of 15) is satisfied ”is satisfied.

  Further, the control unit 89 is configured so as to determine whether or not the walking type lawn mower 10A is in operation by adopting the configuration of the walking type lawn mower 10A of the modified example shown in FIGS. can do.

FIG. 12 is a schematic system diagram of a walking lawn mower according to a modification of the present invention.
The walking-type lawn mower 10A according to the modified example has basically the same configuration and function as the walking-type lawn mower 10 shown in FIGS. 1 to 11, and the description thereof will be omitted. A walking lawn mower 10A according to this modification is characterized in that a traveling lever operation detection sensor 201 is provided in the operation unit 18.

  The travel lever operation detection sensor 201 detects that the transmission 25 is operated by the travel lever 42 so as to transmit the output of the engine 14 to the rear wheel 13 (corresponding to a so-called clutch coupling operation). For example, it consists of a switch. When the traveling lever 42 is swung forward to the ON position, the traveling lever operation detection sensor 201 detects that the coupling operation has been performed, and issues a detection signal to the control unit 89.

FIG. 13 is a control flowchart of the main routine of the control unit in the walking lawnmower according to the modification of the present invention, in which a part of the main routine shown in FIG. 7 is changed and only the changed part is shown. It is.
The main routine of this modification is characterized in that step ST12A is added. In ST12, it is checked whether or not the work clutch lever 41 is in the off position. If NO, it is determined that the cutter 15 has been operated, and the process proceeds to ST12A.

  In ST12A, it is checked whether or not the travel lever 42 is in the off position. If YES, the process proceeds to ST13, and if NO, it is determined that the walking lawnmower 10 has traveled, and the process proceeds to ST14. As shown in FIG. 5, the position when the operator releases his / her hand from the traveling lever 42 is the off position. The position of the travel lever 42 is determined by a detection signal from the travel lever operation detection sensor 201 (see FIG. 12).

FIG. 14 is a control flowchart of a subroutine of the control unit in the walking lawnmower according to the modification of the present invention, and shows a part of the subroutine shown in FIG.
The subroutine of this modified example is characterized in that step ST101A is added. In ST101, it is checked whether or not the working clutch lever 41 is in the ON position. If YES, it is determined that the cutter 15 has been operated, and the process proceeds to ST101A.
In ST101A, it is checked whether or not the travel lever 42 is in the on position. If YES, it is determined that the walking lawnmower 10 has been traveled, and the process proceeds to ST102. If NO, the process returns to ST17 shown in FIG.

FIG. 15 is a control flowchart in which a part of the subroutine of the control unit in the walking lawnmower according to the modification of the present invention is changed, and shows a part of the subroutine in the modification shown in FIG. It is.
The subroutine in which a part thereof is changed is characterized in that step ST201A is added. In ST201, it is determined whether or not the work clutch lever 41 is in the on position. If YES, it is determined that the cutter 15 has been operated, and the process proceeds to ST201A.
In ST201A, it is checked whether or not the travel lever 42 is in the on position. If YES, it is determined that the walking lawn mower 10 has traveled, and the process proceeds to ST202. If NO, the process proceeds to ST213.

  As described above, the control unit 89 shown in FIGS. 13 to 15 causes the walking lawn mower 10 to travel under the condition that the cutter 15 is operated (ST12 in FIG. 13, ST101 in FIG. 14, ST201 in FIG. 15). The configuration for determining that the condition that the walking lawn mower 10 is in operation is satisfied when both of the conditions are satisfied (ST12A in FIG. 13, ST101A in FIG. 14, ST201A in FIG. 15). It is.

Next, the control flow further changed based on FIGS. 16 to 18 will be described.
FIG. 16 is a control flowchart in which a part of the main routine shown in FIG. 13 is changed. In ST12, the main routine shown in FIG. 16 checks whether or not the working clutch lever 41 is in the off position. If YES, the process proceeds to ST12A, and if NO, the cutter 15 is determined to have been operated, and the process proceeds to ST14.
In ST12A, it is checked whether or not the travel lever 42 is in the off position. If YES, the process proceeds to ST13, and if NO, it is determined that the walking lawnmower 10 has traveled, and the process proceeds to ST14.

FIG. 17 is a control flowchart in which a part of the subroutine shown in FIG. 14 is changed. The subroutine shown in FIG. 17 checks whether or not the work clutch lever 41 is in the ON position in ST101. If YES, it is determined that the cutter 15 has been operated, and the process proceeds to ST102. If NO, the process proceeds to ST101A.
In ST101A, it is checked whether or not the travel lever 42 is in the on position. If YES, it is determined that the walking lawnmower 10 has been traveled, and the process proceeds to ST102. If NO, the process returns to ST17 shown in FIG.

FIG. 18 is a control flowchart in which a part of the subroutine shown in FIG. 15 is changed. The subroutine shown in FIG. 18 checks whether or not the working clutch lever 41 is in the ON position in ST201. If YES, it is determined that the cutter 15 is operated, and the process proceeds to ST202. If NO, the process proceeds to ST201A.
In ST201A, it is checked whether or not the travel lever 42 is in the on position. If YES, it is determined that the walking lawn mower 10 has traveled, and the process proceeds to ST202. If NO, the process proceeds to ST213.

  As described above, the control unit 89 shown in FIGS. 16 to 18 causes the walking lawn mower 10 to travel under the condition that the cutter 15 is operated (ST12 in FIG. 16, ST101 in FIG. 17, ST201 in FIG. 18). If any one of the conditions (ST12A in FIG. 16, ST101A in FIG. 17, ST201A in FIG. 18) is satisfied, the condition that the walking lawnmower 10 is in operation is satisfied. It is the structure to judge.

According to the present invention shown in FIGS. 12 to 18, in addition to the effects of the invention shown in FIGS.
That is, in the present invention, the control unit 89 determines that the walking lawn mower 10 is operating when the cutter 15 (working unit 15) is operated or when the walking lawn mower 10 is run. Therefore, the target rotational speed Nt can be changed more finely stepwise in accordance with fluctuations in the work load of the cutter 15 itself and fluctuations in the travel load of the walking lawn mower 10. As a result, the working efficiency of the walking lawnmower 10 can be further increased.

  In the above-described embodiments and modifications of the present invention, the engine-driven work machine is not limited to the walk-type lawn mower, but a work machine having various working units driven by the engine, for example, tillage Can be applied to the machine.

  The engine-driven work machine of the present invention is suitable for a walk-type lawn mower or a tillage machine that works on a working part while running on drive wheels.

It is a left view which shows the walk-type lawn mower which concerns on this invention. 1 is a schematic system diagram of a walking lawn mower according to the present invention. It is the perspective view which looked around the rear part of the handle of the walk type lawn mower according to the present invention from the upper right front. 4 is a view taken in the direction of arrow 4 in FIG. FIG. 5 is a view taken in the direction of arrow 5 in FIG. It is a flowchart which shows a series of procedures until the control part performs a control process from the starting operation time of the engine which concerns on this invention. It is a control flowchart (main routine) of the control part which concerns on this invention. It is a control flowchart (subroutine) of the control part which concerns on this invention. It is operation | movement explanatory drawing of the walk-type lawn mower which concerns on this invention. It is a control flowchart (subroutine) of the modification of the control part which concerns on this invention. It is operation | movement explanatory drawing of the modification of the engine drive type working machine which concerns on this invention. It is a typical systematic diagram of the walking type lawn mower of the modification concerning the present invention. It is a control flowchart of the main routine of the control part in the walk-type lawn mower of the modification which concerns on this invention. It is a control flowchart of the subroutine of the control part in the walk-type lawn mower of the modification which concerns on this invention. It is the control flowchart which changed a part of subroutine of the control part in the walk-type lawn mower of the modification which concerns on this invention. It is the control flowchart which changed a part of main routine shown in FIG. It is the control flowchart which changed a part of subroutine shown in FIG. 16 is a control flowchart in which a part of the subroutine shown in FIG. 15 is changed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10,10A ... Engine drive type working machine (walking-type lawn mower), 13 ... Drive wheel, 14 ... Engine, 15 ... Working part (cutter), 21 ... Clutch, 25 ... Transmission, 41 ... Clutch lever for work, 42 DESCRIPTION OF SYMBOLS ... Travel lever, 60 ... Target rotation speed change operation part, 65 ... Target rotation speed switch operation part (rotation mode changeover switch), 66 ... Speed change switch, 67 ... Boost lever, 68 ... Clutch operation detection sensor for work, 83 ... throttle valve control motor, 89 ... control unit, 92 ... throttle valve, 201 ... travel lever operation detection sensor, NH ... target high speed rotation speed, NL ... target low speed rotation speed, NM ... target medium speed rotation speed, Nr ... actual , Nt... Target rotation speed, Tc... Time when change command is issued (elapsed time).

Claims (4)

In an engine-driven work machine that electrically opens and closes a throttle valve so that the actual speed of the engine that drives the working unit matches the target speed, the engine-driven work machine includes:
A target rotational speed changing operation unit for issuing a change command so as to change the target rotational speed stepwise and temporarily according to an artificial operation;
Only when the condition that the engine-driven work machine is operating is satisfied, the target rotational speed is changed according to the change command of the target rotational speed changing operation unit, and the changed target rotational speed is set. An engine-driven work machine comprising: a control unit that controls opening and closing of the throttle valve so that the actual rotational speed matches.   When the control unit satisfies at least one of a condition that the working unit is operated and a condition that the engine-driven working machine is driven, the engine-driven working machine is operating. The engine-driven work machine according to claim 1, wherein the engine-driven work machine is configured to determine that a certain condition is satisfied. The target rotational speed that is changed stepwise by the change command of the target rotational speed changing operation unit is the rotational speed at which the engine can generate the maximum torque or a target medium speed rotational speed close to the rotational speed, There are two stages: a rotation speed at which the engine can generate a maximum output at a speed higher than the high speed rotation speed or a target high speed rotation speed close to the rotation speed,
The said control part is comprised so that it may change to the said target medium speed rotational speed and the said target high speed rotational speed according to the change command of the said target rotational speed change operation part. 2. The engine-driven work machine according to 2.   The target rotation speed changing operation unit is configured to issue the change command continuously only when being operated artificially, and the control unit is configured to perform the change command according to a time when the change command is issued. The engine-driven work machine according to claim 1 or 2, characterized in that the target rotational speed is increased.

Images