Walking type work machine

Abstract

To provide a walking type work machine capable of securing stability of a driving operation without difficulty when switching to a backward movement state during work.SOLUTION: A walking type work machine includes: a transmission 2C that transmits power from a driving source 11 capable of changing output rotation to a traveling device 13 and can switch forward movement and backward movement of the traveling device 13; speed setting means 19 capable of setting target speed of the driving source 11 through a manual operation; forward / backward movement detection means S2 for detecting whether the transmission 2C is in a forward movement state or backward movement state; and a control device CU for controlling an operation of the driving source 11. The control device CU controls the operation of the driving source 11 so as to reach the target speed when the forward movement state is detected on the basis of the detection result obtained by the forward / backward movement detection means S2, and controls the operation of the driving source 11 so as to reach set speed lower than the target speed when transition from the forward movement state to the backward movement state is detected.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a walk-behind working machine such as a walk-behind cultivator or a walk-behind rice transplanter. [Background technology]

[0002] In a walk-behind cultivator, which is an example of a walk-behind work machine, an engine is mounted as a drive source, and a throttle lever for adjusting the engine speed is provided near the steering handle. The engine output speed is adjusted to a target speed set by the throttle lever (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2013-170654 A Summary of the Invention [Problem to be solved by the invention]

[0004] When agricultural work is performed in a field using a walk-behind cultivator, the operator operates the cultivator by holding the steering handle and performs tilling work while walking together with the traveling walk-behind cultivator. In this case, the setting value of the throttle lever is generally set to a high output rotation speed close to the maximum output of the engine when performing work while the machine is traveling forward, since the driving load is large. However, depending on the work situation, the machine may be switched from a state in which it is traveling forward to a state in which it is traveling backward. In this case, if the target speed for forward traveling is still set by the throttle lever, when reverse traveling is started, if the engine is operated at a high output rotation speed, the machine may move at a high speed, which may cause unstable driving operation by the operator.

[0005] When shifting into reverse, the operator can operate the throttle lever to reduce the engine output rotation and thereby reduce the speed of the implement; however, this requires the operator to also perform the operation of shifting the transmission, making the operation complicated.

[0006] Therefore, there has been a demand for a walk-behind working machine that can ensure stable driving operation without hassle when switching from a forward motion state to a reverse motion state during work. [Means for solving the problem]

[0007] The characteristic configuration of the walk-behind working machine of the present invention is that it comprises a traveling device, a drive source capable of changing output rotation, a transmission that transmits power from the drive source to the traveling device and can switch between forward and reverse motion of the traveling device, a speed setting means that can manually set a target speed of the drive source, forward / reverse detection means that detects whether the transmission is in a forward or reverse state, and a control device that controls the operation of the drive source, and that when the forward state is detected based on the detection result of the forward / reverse detection means, the control device controls the operation of the drive source so that the target speed is achieved, and when a transition from the forward state to the reverse state is detected, the control device controls the operation of the drive source so that the set speed is lower than the target speed.

[0008] According to the present invention, the control device controls the operation of the drive source based on the detection information of the forward / reverse detection means. In the forward state, the control device controls the operation of the drive source so that the target speed set by the speed setting means is reached. Then, when a transition from the forward state to the reverse state is detected, the control device controls the operation of the drive source so that the set speed, which is lower than the target speed, is reached.

[0009] As a result, the operator only needs to change the speed change gear, making it possible to ensure stable driving operation without hassle when switching from forward to reverse during work.

[0010] In the present invention, it is preferable that a manually operated operating tool capable of operating the transmission on and off is provided, and that the forward / reverse detection means is a detection switch that detects when the operating tool is operated to a forward position and when the operating tool is operated to a reverse position.

[0011] According to this configuration, the operating state of the operating tool operated by the operator is detected by the detection switch, so it is possible to accurately detect whether the transmission is in a forward or reverse state.

[0012] In the present invention, it is preferable that the control device controls the operation of the drive source so that the set speed is reached before the traveling device starts to move backward.

[0013] According to this configuration, when the machine starts to move backward, the drive source is set to a low speed, so that the operator can drive the machine safely without panicking.

[0014] In the present invention, it is preferable that the drive source is an engine equipped with an electronically controlled fuel supply device.

[0015] According to this configuration, since the engine is equipped with an electronically controlled fuel supply device, there are advantages such as reduced influence of external environment such as temperature, and stable operation. In addition, since the reduction in engine speed during turning is realized by the control of the electronically controlled fuel supply device, there are advantages such as smooth change in speed and arbitrary setting of the target speed for reduction.

[0016] In the present invention, it is preferable that the control device detects a transition from the forward state to the reverse state and controls the operation of the drive source so that the set speed is achieved, and then controls the operation of the drive source so that the output rotation is higher than the set speed.

[0017] When starting reverse travel, there is a risk that the operator's driving operation may become unstable, but after reverse travel has begun, the vehicle's traveling posture is likely to stabilize. Therefore, according to this configuration, when starting reverse travel, the vehicle travels at a low speed, so stability of driving operation can be ensured, and after starting reverse travel, the drive source operates at an output rotation speed higher than the set speed, so that work efficiency can be improved. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a left side view showing the entire walk-behind cultivator. [Diagram 2] FIG. 2 is a plan view showing the entire walk-behind cultivator. [Diagram 3] FIG. 2 is a diagram showing a power transmission system and an operating system. [Figure 4] 4 is a time chart showing a fluctuation state of engine output rotation; DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of a walk-behind cultivator, which is an example of a walk-behind working machine according to the present invention, will be described with reference to the drawings. The present invention is not limited to the following embodiment, and various modifications are possible without departing from the gist of the present invention.

[0020] In addition, unless otherwise specified, the front-rear and left-right directions in the explanation of this embodiment are described as follows: In other words, the forward traveling direction when the walk-behind cultivator is traveling for work (see arrow FR in Figs. 1 and 2) is "forward", the backward traveling direction (see arrow BK in Figs. 1 and 2) is "rear", the direction corresponding to the right side based on the forward posture in the front-rear direction (see arrow RH in Fig. 2) is "right", and similarly the direction corresponding to the left side (see arrow LH in Fig. 2) is "left".

[0021] [Overall structure] As shown in FIG. 1, the traveling body of the walk-behind cultivator is equipped with an engine 11 as a drive source mounted on an engine frame 10 that constitutes a part of the body frame 1. In this embodiment, the engine 11 is equipped with an electronically controlled fuel supply device FE (FIG. 3). The electronically controlled fuel supply device FE forcibly injects fuel into a combustion cylinder using an actuator and adjusts the amount of intake air using a throttle valve, and can change and adjust the rotation speed of the engine 11. In other words, the electronically controlled fuel supply device FE includes an electronically controlled fuel injection device. The electronically controlled fuel supply device FE also has the function of an electronic governor that suppresses fluctuations in the rotation speed of the engine 11. Therefore, there are advantages such as reduced influence of external environments such as temperature, stabilization of the operation of the engine 11, and realization of detailed control.

[0022] A transmission case 2, which constitutes the vehicle frame 1 together with the engine frame 10, is connected integrally to the rear side of the engine frame 10. The engine 11 and the transmission case 2 are connected together via a belt transmission mechanism 12 so as to be capable of transmitting power.

[0023] The transmission case 2 is formed in a bifurcated shape, including a front case 2A extending downward and a rear case 2B extending diagonally downward and rearward.

[0024] Left and right traveling devices 13 are supported on the lower part of the front case 2A via axles 20. In this embodiment, the traveling devices 13 are wheels. The traveling devices 13 may be devices of other forms, such as crawler traveling devices.

[0025] A working device 14 is supported on the rear case 2B via a drive shaft 21. In this embodiment, the working device 14 is a rotary tilling device. The working device 14 may be another type of device, such as a ridge maker or a seed sowing machine.

[0026] Power from the engine 11 is transmitted to a transmission 2C having a gear shift mechanism inside the transmission case 2 via a belt transmission mechanism 12. The belt transmission mechanism 12 is configured so that the power transmission can be turned on and off by a clutch operating arm 12a. The belt transmission mechanism 12 and the clutch operating arm 12a form a main clutch 31 (FIG. 3) that connects and disconnects the power transmission to the traveling drive system and the working drive system.

[0027] In addition to the transmission 2C, a working clutch 32, a running clutch 33, and a differential mechanism 34 are provided inside the transmission case 2 (see FIG. 3). Power supplied from the main clutch 31 through the transmission 2C is branched and transmitted to the working clutch 32 and the running clutch 33.

[0028] The transmission 2C can switch between forward and reverse movement of the traveling device 13. The working clutch 32 turns on and off the power transmission to the working device 14. The traveling clutch 33 turns on and off the power transmission to the traveling device 13 via a differential mechanism 34. The differential mechanism 34 can regulate the differential between the left and right traveling devices 13.

[0029] A gear shift lever 15 as a manually operated operating tool extends obliquely upward and rearward from the upper part of the transmission case 2. By operating this gear shift lever 15, forward and backward switching of the transmission 2C can be performed.

[0030] A control handle 16 extends toward the rear of the aircraft from the rear of the transmission case 2. A turning lever 17, a stop switch 18, and a throttle lever 19 serving as a target speed setting means are disposed on the right side of the control handle 16. A main clutch lever 3 for switching on and off a main clutch 31 is disposed on the rear end side of the control handle 16.

[0031] The turning lever 17 is used to operate the working clutch 32 and the differential mechanism 34 . When the swing lever 17 is in the ON position, the working clutch 32 is in a state where it does not transmit power (clutch disengaged), and the differential mechanism 34 is in a state where it does not restrict the differential movement of the traveling device 13 (diff-lock disengaged). When the swing lever 17 is in the OFF position, the working clutch 32 is in a state where it transmits power (clutch engaged), and the differential mechanism 34 is in a state where it restricts the differential movement of the traveling device 13 (diff-lock engaged).

[0032] A stop switch 18 is wired to the control system of the engine 11 for use in stopping the engine 11 .

[0033] The throttle lever 19 is used to operate the rotation speed of the engine 11 and is connected to a control device CU that controls the electronically controlled fuel supply device FE.

[0034] In the walk-behind cultivator configured as above, the operator operates the walk-behind cultivator by holding the control handle 16 and walks together with the moving walk-behind cultivator. Turning is performed by the operator turning the control handle to the left or right to change the direction of travel of the walk-behind cultivator.

[0035] [Power transmission system and operating system] The walking type cultivation machine of this embodiment is equipped with a running device 13, an engine 11 as a driving source capable of changing the output rotation, a transmission 2C that transmits power from the engine 11 to the running device 13 and can switch the running device 13 between forward and reverse, a speed change lever 15 as an operating tool that can manually switch the transmission 2C between a forward state and a reverse state, a throttle lever 19 as a speed setting means that can manually set a target speed of the engine 11, a speed change detection sensor S2 as a forward / reverse detection means that detects whether the transmission 2C is in a forward state or a reverse state, and a control device CU that controls the operation of the engine 11, and when a forward state is detected based on the detection result of the speed change detection sensor S2, the control device CU controls the operation of the engine 11 so that the target speed is achieved, and when a transition from the forward state to the reverse state is detected, controls the operation of the engine 11 so that the set speed is lower than the target speed.

[0036] The specific details will be explained below. FIG. 3 shows a power transmission system and an operating system of the walk-behind type cultivator of this embodiment.

[0037] The power transmission system will be described. Power from the engine 11 is transmitted to the working device 14 via the main clutch 31, the transmission 2C, and the working clutch 32. Power from the engine 11 is transmitted to the traveling device 13 via the main clutch 31, the transmission 2C, the traveling clutch 33, and the differential mechanism 34. Note that the traveling clutch 33 is not necessarily required, and the configuration may not include the traveling clutch 33. The transmission 2C transmits power from the engine 11 to the traveling device 13, and is capable of switching between forward and reverse movement of the traveling device 13.

[0038] The operating system will now be described. A gear shift detection sensor S2 is provided as forward / reverse detection means for detecting whether the transmission 2C is in a forward or reverse state, and a signal from the sensor S2 is transmitted to the control unit CU via a transmission line 15b. When a forward state is detected based on the detection result of the gear shift detection sensor S2, the control unit CU controls the operation of the engine 11 so that the target speed is reached, and when a transition from the forward state to the reverse state is detected, the control unit CU controls the operation of the engine 11 so that the set speed is lower than the target speed. Then, when the state is switched from the reverse state to the forward state, the output rotation of the engine 11 is gradually increased from the neutral speed toward the target speed set by the throttle lever 19.

[0039] Also, a turning operation device (working clutch 32 and differential mechanism 34) switchable between a turning operating state and a straight-travel operating state is provided as the operated device Y, and the turning operation device (working clutch 32 and differential mechanism 34) is switched between the turning operating state and the straight-travel operating state by a turning lever 17 as the operating tool X. Also, a speed change device 2C switchable between a forward state and a reverse state is provided as the operated device Y, and is switched between the reverse state and the forward position by a speed change lever 15 as the operating tool X. The turning lever 17 is operated by the operator from the off position to the on position when the walk-behind cultivator turns, and is operated by the operator from the on position to the off position when changing from the turning state to the straight-travel state.

[0040] The swing lever 17 and the work clutch 32 are mechanically connected by a first operation wire 17a. The first operation wire 17a mechanically transmits the operation received by the swing lever 17 to the work clutch 32. When the swing lever 17 is operated from the OFF position to the ON position, the work clutch 32 changes from a state in which it transmits power to a state in which it does not transmit power. This causes the working device 14 to stop operating. When the swing lever 17 is operated from the ON position to the OFF position, the work clutch 32 changes from a state in which it does not transmit power to a state in which it transmits power.

[0041] The turning lever 17 and the differential mechanism 34 are mechanically connected by the second operation wire 17b. The second operation wire 17b mechanically transmits the operation received by the turning lever 17 to the differential mechanism 34. When the turning lever 17 is operated from the OFF position to the ON position, the differential mechanism 34 changes from a state in which the differential between the left and right traveling devices 13 is restricted to a state in which the differential is not restricted. Then, the left and right traveling devices 13 are permitted to operate, making it easier for the operator to turn the walking type cultivator. When the turning lever 17 is operated from the ON position to the OFF position, the differential mechanism 34 changes from a state in which the differential between the left and right traveling devices 13 is not restricted to a state in which the differential is restricted. Note that the turning lever 17 and the working clutch 32 or the differential mechanism 34 are not limited to a configuration in which they are mechanically connected using an operation wire, and may be a configuration in which the working clutch 32 or the differential mechanism 34 is switched by an actuator operated by the operation of the turning lever 17.

[0042] The rotating lever 17 is configured to electrically transmit the operation received to the control unit CU. That is, a switch (e.g., a limit switch) (not shown) in contact with the rotating lever 17 detects that the rotating lever 17 has been operated to the ON position, and a signal from the switch is transmitted to the control unit CU via a transmission line 17c.

[0043] The throttle lever 19 is configured to transmit the operation received by the throttle lever 19 to the control unit CU. That is, a sensor (not shown) is provided to detect the position of the throttle lever 19, and the signal from the sensor is transmitted to the control unit CU via a transmission line 19a.

[0044] The main clutch lever 3 and the main clutch 31 are mechanically connected by a third operating wire 3a. The third operating wire 3a mechanically transmits the operation received by the main clutch lever 3 to the main clutch 31. When the main clutch lever 3 is operated to the disengaged position, the main clutch 31 enters a clutch-disengaged state in which power transmission is cut off. When the main clutch lever 3 is operated to the engaged position, the main clutch 31 enters a clutch-engaged state in which the power of the engine 11 is transmitted to the downstream transmission side. In this state, the power of the engine 11 is transmitted to the traveling device 13 via the traveling clutch 33 and the differential mechanism 34, and is also transmitted to the working device 14 via the working clutch 32, allowing tilling work to be performed while traveling.

[0045] A clutch detection sensor S1 is provided as a clutch detection means for detecting whether the main clutch 31 is in an engaged state or disengaged state, and a signal from the clutch detection sensor S1 is transmitted to the control device CU via the second transmission line 3b. Based on the detection result of the clutch detection sensor S1, when an engaged state is detected, the control device CU controls the operation of the engine 11 so that the target speed is reached, and when a disengaged state is detected, the control device CU controls the operation of the engine 11 so that the set speed is reached which is lower than the target speed.

[0046] The control unit CU is a so-called ECU, and includes a memory device ME and a CPU (not shown). The memory device ME includes an HDD and non-volatile RAM, and stores programs for controlling the walking type cultivator, permanent data, and temporary data. The functions of the control unit CU described below are realized by the CPU executing the programs.

[0047] The control unit CU controls the electronically controlled fuel supply unit FE based on the operation received by the throttle lever 19 to control the rotation speed of the engine 11.

[0048] In this embodiment, when the control unit CU detects that the transmission 2C is in a forward state based on the detection result of the shift detection sensor S2, it controls the operation of the engine 11 so that the target speed is achieved, and when it detects that the transmission 2C has switched from the forward state to the reverse state, it controls the operation of the engine 11 so that the set speed is lower than the target speed.

[0049] This control is premised on the engine 11 having started and running. When the engine 11 has started and the operator operates the shift lever 15, and the shift detection sensor S2 detects that the transmission 2C is in a forward drive state, the electronically controlled fuel supply device FE is controlled so that the output rotation of the engine 11 becomes the target speed set by the throttle lever 19, thereby controlling the rotation speed of the engine 11.

[0050] The target speed is set by the operator by operating the throttle lever 19. When tilling work is performed with the implement 14 while traveling, the traveling load and the drive load of the implement 14 are large, so that the target speed is set to a value that results in a large output rotation close to the maximum output of the engine 11, taking into consideration the work efficiency.

[0051] When the shift detection sensor S2 detects a transition of the transmission 2C from a forward state to a reverse state as the operator operates the shift lever 15, the electronically controlled fuel supply device FE is controlled so that the set speed becomes lower than the target speed. However, if a target speed lower than the set speed, such as an idling speed or a target speed close to the idling speed, is set by operating the throttle lever 19, control to reduce the rotation speed of the engine 11 is not executed.

[0052] The control contents of the control unit CU will be described with reference to the time chart of FIG. If the first set value M1 is set by the throttle lever 19 at the start of work with the main clutch 31 engaged, the control unit CU controls the electronically controlled fuel supply unit FE so that the output speed of the engine 11 becomes the first target speed N1 corresponding to the first set value M1. Note that at this time, if the engine 11 is in an unloaded state, the output speed of the engine 11 becomes the first target speed N1, but when tilling work is being performed, the driving load is large, so the actual rotation speed of the engine 11 may be lower than the first target speed N1.

[0053] When working while driving forward, if the throttle lever 19 is set to a second set value M2 that is lower than the first set value M1, the control unit CU controls the electronically controlled fuel supply unit FE so that the output speed of the engine 11 becomes a second target speed N2 that corresponds to the second set value M2.

[0054] When starting work, the transmission 2C is switched from the neutral state to the forward state. At this time, even if the shift detection sensor S2 detects that the state has been switched to the forward state, the output speed of the engine 11 is maintained at the first target speed N1.

[0055] When the shift detection sensor S2 detects a transition from a forward drive state to a reverse drive state during work while the vehicle is traveling forward, the electronically controlled fuel supply device FE is controlled so that the output speed of the engine 11 becomes a third target speed N3, which is slower than the first target speed N1. When the vehicle switches to the reverse drive state in this manner, the output speed of the engine 11 can be reduced without operating the throttle lever 19, and the vehicle can start traveling backward at a low speed without the hassle of operation.

[0056] The third target speed N3 may be a value close to the idling speed, which is the lower limit of the characteristics of the engine 11, or may be a value higher than the idling speed.

[0057] The control device CU controls the operation of the engine 11 so that the set speed is reached before the traveling device 13 starts to move backward. In other words, the operation timing is set so that the timing at which the shift detection sensor S2 detects the switch from the forward state to the reverse state is earlier than the timing at which the shift state of the transmission 2C changes with the shift lever 15 being switched from forward to reverse.

[0058] The control device CU controls the operation of the engine 11 so that the engine speed becomes a set speed (third target speed N3) when the shift detection sensor S2 detects a transition from a forward drive state to a reverse drive state, and then controls the operation of the engine 11 so that the output speed becomes higher than the set speed. That is, as shown in Fig. 4, when a set time has elapsed since the forward drive state is switched to the reverse drive state and the electronically controlled fuel supply device FE is controlled so that the output speed of the engine 11 becomes the third target speed N3, the control device CU controls the electronically controlled fuel supply device FE so that the output speed of the engine 11 gradually increases from the third target speed N3.

[0059] When the shift lever 15 is switched from the reverse position to the forward position and this is detected by the shift detection sensor S2, the output rotation of the engine 11 is gradually increased from the third target speed N3 toward the first target speed N1. However, when the shift lever 15 is switched from the forward position to the reverse position, if a target speed lower than the neutral speed is set by the throttle lever 19, the output rotation of the engine 11 is not reduced. When the shift lever 15 is switched from the reverse position (second operating state) to the forward position (first operating state), if a value close to or lower than the third target speed N3 is set by the throttle lever 19, no speed increase control (gradual increase) is performed. For example, when a value lower than a predetermined threshold value is set at the throttle lever 19, the control unit CU does not perform speed increase control (gradual increase) when the shift lever 15 is switched from the reverse position (second operating state) to the forward position (first operating state), but controls the electronically controlled fuel supply unit FE so that the output rotation of the engine 11 becomes the value set at the throttle lever 19.

[0060] Also, when the work is interrupted midway and the main clutch 31 is switched to the disengaged state, the control unit CU controls the electronically controlled fuel supply unit FE so that the output speed of the engine 11 becomes a fourth target speed N4, which is a set speed lower than the first target speed N1. In this way, when the main clutch 31 is in the disengaged state, the output speed of the engine 11 can be reduced without operating the throttle lever 19, and it is possible to suppress wasteful consumption of fuel and reduce noise without the hassle of operation. The fourth target speed N4 may be a value close to the idling speed or a value higher than the idling speed. The fourth target speed N4 may be lower than the third target speed N3 as shown in FIG. 4, or may be higher than the third target speed N3.

[0061] During work, when the swing lever 17 is operated to the ON position to perform swing, the output rotation of the engine 11 is suddenly reduced to a swing speed (for example, the third target speed N3). The swing speed may be a value close to the idling speed, which is the lower limit value in terms of the characteristics of the engine 11, but if the value is a little higher than the idling speed, it is easier to return to work. Then, when the swing lever 17 is switched from the ON position to the OFF position, the output rotation of the engine 11 gradually increases. That is, it slowly increases from the third target speed N3 to the first target speed N1. However, when the swing lever 17 is switched from the ON position to the OFF position, if a value close to or lower than the third target speed N3 is set in the throttle lever 19, the speed increase control (gradual increase) is not performed. For example, when a value lower than a predetermined threshold value is set on the throttle lever 19, the control unit CU does not perform speed increase control (gradual increase) when the turning lever 17 is switched from the ON position to the OFF position, but controls the output rotation of the engine 11 to the value set on the throttle lever 19.

[0062] [Another embodiment] (1) As a forward / reverse detection means, the shift lever 15 may be provided with a potentiometer that detects the amount of swing operation associated with switching between forward and reverse, and the control unit CU may determine whether the vehicle is in a forward or reverse state by judging the level of the detection value of the potentiometer.

[0063] (2) When a transition from a forward state to a reverse state is detected and the electronically controlled fuel supply device FE is controlled so as to achieve a low third target speed N3, the operation of the engine 11 may be controlled so as to achieve the set speed at the same time that the traveling device 13 begins to reverse.

[0064] (3) After detecting a transition from a forward drive state to a reverse drive state and controlling the operation of the engine 11 to achieve the set speed (third target speed N3), the set speed may be maintained even if the shift detection sensor S2 detects a forward drive state. In this case, when a new target speed is set by manually operating the throttle lever 19, the output rotation of the engine 11 may be returned to the target speed.

[0065] (4) The engine 11 may not include the electronically controlled fuel supply device FE. In other words, the engine 11 may be one in which the amount of fuel supplied to the engine is adjusted by a mechanical carburetor or the like.

[0066] (5) The electronically controlled fuel supply device FE may be controlled so that the output speed of the engine 11 gradually increases from the third target speed N3 after a predetermined distance has been traveled since the switch from the forward state to the reverse state is detected and the operation of the engine 11 is controlled to the set speed. Alternatively, the operation of the engine 11 may be controlled so that the output speed becomes higher than the set speed immediately after a set time has elapsed or after a predetermined distance has been traveled since the transition from the forward state to the reverse state is detected and the operation of the engine 11 is controlled to the set speed. The output speed may be, for example, a target speed corresponding to a set value set by the throttle lever 19.

[0067] (6) The walk-behind cultivator may be provided with an electric motor as a drive source instead of the engine 11.

[0068] (7) The engine 11 may not include the electronically controlled fuel supply device FE. In other words, the engine 11 may be one in which the amount of fuel supplied to the engine is adjusted by a mechanical carburetor or the like.

[0069] (8) A side clutch mechanism may be provided in place of the differential mechanism 34. [Industrial Applicability]

[0070] The present invention can be applied to walk-behind working machines, such as walk-behind cultivators, walk-behind rice transplanters, and walk-behind vegetable transplanters. [Explanation of symbols]

[0071] 2C Transmission 11 Engine (power source) 13 Running gear 15 Gear shift lever (operating tool) 19 Throttle lever (speed setting means) CU Control Unit FE Electronically controlled fuel supply system S2 Gear change detection sensor (forward / reverse detection means)

Claims

1. The running gear, A drive source capable of changing output rotation; a transmission that transmits power from the drive source to the traveling device and is capable of switching between forward and reverse travel of the traveling device; a speed setting means for manually setting a target speed of the driving source; a forward / reverse detection means for detecting whether the transmission is in a forward or reverse state; A control device that controls the operation of the drive source is provided. The control device, when the forward state is detected based on the detection result of the forward / reverse detection means, controls the operation of the drive source so that the target speed is achieved, and when a transition from the forward state to the reverse state is detected, controls the operation of the drive source so that a set speed that is lower than the target speed is achieved.

2. A manually operated operating tool capable of turning the transmission on and off is provided, 2. The walk-behind working machine according to claim 1, wherein the forward / reverse movement detection means is a detection switch that detects when the operating tool is operated to a forward position and when the operating tool is operated to a reverse position.

3. 2. The walk-behind working machine according to claim 1, wherein the control device controls the operation of the drive source so that the set speed is reached before the traveling device starts to move backward.

4. 2. The walk-behind work machine according to claim 1, wherein the drive source is an engine equipped with an electronically controlled fuel injection device.

5. 5. The walk-behind working machine according to claim 1, wherein the control device detects a transition from the forward state to the reverse state, controls the operation of the drive source so as to achieve the set speed, and then controls the operation of the drive source so as to achieve an output rotation higher than the set speed.

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