Patent ID: 12201052

DESCRIPTION OF THE EMBODIMENTS

In the work machine of the related art described above, there has been a case where improvement in a driving mode of a working mechanism is required for the purpose of further improving the efficiency and performance of work.

An illustrative object of an embodiment of the present invention is to provide a technique advantageous for further improvement in efficiency, performance, and the like of a work machine.

Hereinafter, embodiments will be described in detail with reference to the attached drawings. Note, the following embodiments are not intended to limit the scope of the claimed invention, and limitation is not made to an invention that requires a combination of all features described in the embodiments. Two or more of the multiple features described in the embodiments may be combined as appropriate. Furthermore, the same reference numerals are given to the same or similar configurations, and redundant description thereof is omitted.

In addition, in each drawing, arrows X, Y, and Z indicate directions orthogonal to one another, the X direction indicates a front-and-rear direction of a work machine W, the Y direction indicates a vehicle width direction (a left-and-right direction) of the work machine W, and the Z direction indicates an up-and-down direction. To be noted, in the following description, the left-and-right direction refers to the left and right in a state of facing the forward side of the work machine W.

<Outline of Work Machine>

FIG.1is a side view illustrating the outline of the work machine W according to an embodiment, andFIG.2is a plan view schematically illustrating an internal configuration of the work machine W ofFIG.1. The work machine W is a so-called walk-type lawn mower in which a worker operates an operation unit6, which will be described later, while walking behind the work machine W to cut the lawn grass. The work machine W includes a main body portion1and an operation unit6that operates the main body portion1. The main body portion1includes a working motor M (hereinafter referred to as a motor M), a working unit2, a collection unit3, a traveling unit4, and a control unit5(seeFIG.3).

The motor M is a drive source of the rotary member20of the working unit2, and is an electric motor that rotationally drives the rotary member20. In the present embodiment, the motor M is a three-phase brushless motor. However, other types of motors can be employed as the motor M. The work machine W may include an engine instead of the motor M as a drive source of the rotary member20, or may include an engine and an electric motor as drive sources. In addition, a speed reducer that reduces the rotation speed of the motor M may be provided between the motor M and the rotary member20.

The working unit2performs predetermined work by the rotary member20rotated by the motor M. In the present embodiment, the working unit2includes the rotary member20and a cutter housing22(cover portion) provided to cover the rotary member20and defining a work space S for the working unit2.

The rotary member20rotates with an output shaft1aof the motor M extending in the up-and-down direction as a rotation shaft20a. In the present embodiment, the rotary member20is formed of, for example, a metal material such as iron or aluminum. The rotary member20includes cutting portions201aand201bcapable of cutting lawn grass. In the present embodiment, the rotary member20is a two-blade cutter blade, and has an elongated plate-like extending portion20bextending from the rotation shaft20aon both sides in the radial direction, and cutting portions201aand201bare provided at both ends thereof. That is, the rotary member20includes the plurality of cutting portions201aand201bdifferent in the circumferential direction with respect to the rotation shaft20a. Then, as illustrated inFIG.2, the rotary member20rotates clockwise in plan view, and thus the lawn grass is cut by the cutting portions201aand201b. In the following description, the cutting portions201aand201bmay be collectively referred to as a cutting portion201. To be noted, although a two-blade cutter blade is adopted as the rotary member20in the present embodiment, a single-blade cutter blade or a cutter blade of three or more blades can also be adopted.

In addition, the rotary member20includes fans202aand202bthat urge a target object in a predetermined direction. In the present embodiment, the fans202aand202burge lawn grass which is a target object in a direction in which the lawn grass is introduced into the collection unit3. In the present embodiment, the fans202aand202bare provided behind the cutting portions201aand201bin the rotation direction of the rotary member20, respectively, and are formed so as to be bent upward with respect to the plane in which the rotary member20rotates. As a result, an airflow is generated in the rotation direction by the rotation of the rotary member20, and an airflow is also generated in a direction from the work space S to a discharge port301, so that the cut lawn grass cut is urged by the airflow and introduced into the collection unit. In the following description, the fans202aand202bmay be collectively referred to as a fan202.

The cutter housing22covers the rotary member20and defines the work space S for the rotary member20. The cutter housing22is provided so as to cover the rotary member20, for example, in order to protect the rotary member20, prevent scattering of cut lawn grass, and the like. In the present embodiment, the cutter housing22is provided so as to cover the rotary member20on the front side in the traveling direction of the work machine W and on the side of the work machine W.

The collection unit3is a grass bag that collects the lawn grass cut by the cutting portion201. In the present embodiment, the collection unit3is provided at a rear portion of the work machine W, and is connected to the space covered by the cutter housing22via a discharge port301. With this configuration, the lawn grass cut by the cutting portion201is introduced into the collection unit3together with the airflow generated by the fan202. The structure for discharging air introduced into the collection unit3can be designed as appropriate. For example, the collection unit3may return the introduced air to the space side covered with the cutter housing22again, or may exhaust the air to the rear side of the collection unit3.

To be noted, in the present embodiment, the discharge port301is formed within a range W1in the width direction in which the fan202advances toward the collection unit3. The fan202advances toward the collection unit3(more specifically, the discharge port301) when passing the area between 0° and 180°, which is on the right half side in the cutter housing22in the direction ofFIG.2, and advances away from the collection unit3(more specifically, the discharge port301) when passing the area between 180° and 360°, which is on the left half side. In the present embodiment, the range of the discharge port301in the width direction is formed within the range on the right half side where the fan advances toward the discharge port301. Therefore, the influence of the airflow generated by the fan202moving in the direction away from the discharge port301is suppressed. That is, urging of the lawn grass from the discharge port301side toward the cutter housing22side can be suppressed.

The traveling unit4drives the work machine W to travel. The traveling unit4includes a pair of front wheels40and a pair of rear wheels42each provided separately in the width direction of the work machine W, and a traveling motor44. In the present embodiment, the rotational driving force of the traveling motor44is transmitted to the rear wheels42via an unillustrated transmission mechanism. To be noted, the rotational driving force of the traveling motor44may be transmitted at a rotation speed appropriately converted by the transmission mechanism. In addition, the work machine W may be a front wheel drive in which the rotational driving force of the traveling motor44is transmitted to the front wheels40. To be noted, in one embodiment, the traveling motor44can be omitted. That is, the traveling unit4may include the front wheels40and the rear wheels42, and the work machine W may travel by a force with which the worker pushes the work machine W.

The operation unit6is provided for an operator to operate the work machine W, and includes a bar60, a work operation unit62, and a travel operation unit64. The bar60extends rearward and upward as a pair on the left and right side from one ends fixed to the main body portion1, and is connected at upper ends thereof. The travel operation unit64is provided on the bar60, and receives various inputs for the operation of the traveling unit4by the worker. In addition, the work operation unit62is provided on the bar60, and receives various inputs for the operation of the working unit2by the worker. As an example, the work operation unit62may receive an input regarding switching of start/stop of driving of the working unit2. In addition, when a plurality of modes are provided as the drive mode of the working unit2, the work operation unit62may receive an input for mode switching.

In addition, the main body portion1includes the control unit5that controls the working unit2, and a battery80capable of supplying power to each electrical element of the work machine W. Furthermore, the main body portion1includes a cover member84that covers the working unit2, the battery80, and the like.

<Control Configuration>

Next, a control configuration of the control unit5for the working unit2will be described.FIG.3is a diagram illustrating an example of a hardware configuration of the work machine W, and is a diagram mainly illustrating a configuration related to driving of the working unit2. In one embodiment, the control unit5is a power drive unit (PDU) that controls the driving of the motor M, and includes a micro control unit (MCU)51, an inverter circuit52, and a current sensor53.

The MCU51includes a processor represented by a CPU, a memory such as a RAM and a ROM, and an input/output interface (all not illustrated) that relays transmission and reception of signals between the processor and an external device. The MCU51executes various control by the processor processing a program stored in the memory. Specifically, the MCU51executes rotation speed control and torque control of the motor M, and generates a drive signal to be output to the inverter circuit52. That is, the MCU51constitutes a drive circuit of the motor M. The MCU51can be a computer that implements the present invention related to a program.

The inverter circuit52converts a direct current of the battery80into a motor drive alternating current on the basis of the drive signal output from the MCU51, and outputs the motor drive alternating current to the motor M. To be noted, since the configuration of the inverter circuit52is well known, a detailed description thereof will be omitted. In addition, the current sensor53detects a current value output from the inverter circuit52to the motor M.

In addition, in the present embodiment, the work machine W includes the rotation sensor82that detects the rotation speed and the rotational position, in other words, the rotation angle, of the motor M. For example, the rotation sensor82may be a rotary encoder capable of converting a mechanical displacement amount of rotation into an electric signal and processing the signal to detect a position, a rotation speed, and the like. Note that a sensor that detects a rotation speed such as a tachometer and a sensor that detects a rotational position such as a potentiometer may be provided separately. Note that the rotation sensor82may be omitted in one embodiment. In this case, the mechanical position of the rotating motor M may be estimated by the induced voltage of the motor M or the like. Furthermore, the rotation speed of the motor M may be estimated on the basis of the estimation result.

Note that the configuration illustrated inFIG.3is an example, and other configurations can be adopted. For example, it is also possible to adopt a configuration provided separately from the MCU51that outputs a drive signal and the inverter circuit52that outputs a motor drive current on the basis of the drive signal. In addition, although not illustrated inFIG.3, the drive control of the traveling motor44and the drive control of the motor M for work may be performed by one electronic control unit (ECU). Furthermore, at least a part of the functions implemented by the MCU51may be configured by hardware. In addition, various control may be executed using a micro processing unit (MPU) instead of the MCU51.

FIG.4is a block diagram illustrating an outline of drive control of the motor M by the control unit5. In the present embodiment, a current command value as a drive signal is determined by a rotation speed controller511and a torque controller512realized by the MCU51, and the inverter circuit52controls the output of the motor M on the basis of the current command value.

On the basis of the difference between a predetermined rotation speed command value and the actual rotation speed of the motor M acquired by the rotation sensor82, the rotation speed controller511outputs a torque command value so that the actual rotation speed of the motor M becomes closer to the rotation speed command value. On the basis of the torque command value output from the rotation speed controller511and the drive current value of the motor M acquired by the current sensor53, the torque controller512calculates a torque command value that causes the motor M to behave as intended, and outputs a current command value corresponding thereto to the inverter circuit52. The inverter circuit52converts a direct current of the battery80into a motor drive alternating current on the basis of the current command value output from the torque controller512, and outputs the motor drive alternating current to the motor M.

Here, the control unit5executes the drive control of the motor M described above using vector control. Although the vector control is a well-known technique and thus detailed description thereof will be omitted, the vector control is control in which arithmetic processing is performed while treating a three-phase alternating current value as a two-phase direct current value by coordinate conversion or the like. By using the vector control, not the three-phase alternating current value that constantly changes but the direct current value serves as the control target, so that the drive current value of the motor M can be directly controlled, and more effective torque control can be performed. For example, in a case where only the rotation speed control based on the detection result of the rotation sensor82such as 120° energization control or sine wave control, is performed, it is difficult to control the torque. However, by directly controlling the drive current value using the vector control, it is possible to increase or decrease the rotation speed and the torque even during one rotation of the motor M.

In the present embodiment, the control unit5executes both the rotation speed control and the torque control of the motor M. Therefore, the control unit5can increase or decrease the rotation speed or the torque during one rotation of the motor M by the torque control while rotating the motor M at a predetermined rotation speed by the rotation speed control. That is, the control unit5can microscopically control the torque of the motor M by the torque control while macroscopically controlling the rotation speed of the motor M by the rotation speed control.

Operation Example of Work Machine W

FIG.5Ais a diagram schematically illustrating a state of lawn grass g when the work machine W cuts the lawn grass, andFIGS.5B and5Care diagrams for describing a relationship between the lawn grass g to be cut and a cutting direction of the cutting portion201.

As described above, the cutter housing22is provided on the forward side of the rotary member20. Therefore, when the work machine W performs lawn mowing while moving forward by the traveling unit4, the lawn grass g in front of the rotary member20is pushed down to the forward side by the cutter housing22or the cover member84. Therefore, in a case where the inclination of the lawn grass has not returned to the original state at the time of being cut by the cutting portion201, the lawn grass g is cut by the cutting portion201in a state of being inclined toward the forward side.

Here, when cutting the lawn grass while the cutting portion201is rotating in a range R4from 270° to 360° at the rotation angle illustrated inFIG.2, that is, when cutting the lawn grass on the left half side of the work machine W, the cutting portion201comes into contact with lawn grass g while moving in the forward direction. That is, the cutting portion201comes into contact with the lawn grass in an arrow A direction ofFIG.5B. In this case, since the cutting portion201and lawn grass g come into contact with each other at an obtuse angle Θ1, resistance between the cutting portion201and the lawn grass is relatively low, and the cutting portion201may slip on the lawn grass g. Therefore, as illustrated inFIG.5C, there is a case where the lawn grass g is cut by the cutting portion201in a state of being further pushed down than the state illustrated inFIG.5B. That is, the angle Θ3(FIG.5C) at the time when the lawn grass g is actually cut may be larger than the angle Θ1(FIG.5B) of these at the time when the cutting portion201and the lawn grass g contact each other. As a result, the length of a cut portion g2in a case where the lawn grass is cut during rotation in the range R4may be smaller than the length of the cut portion g1in a case where the cutting is performed without the cutting portion201slipping on the lawn grass g. Therefore, the height of the lawn grass g after cutting tends to shift upward.

In contrast, when cutting the lawn grass while the cutting portion201is rotating in a range R1from 0° to 90° at the rotation angle illustrated inFIG.2, that is, when cutting the lawn grass on the right half side of the work machine W, the cutting portion201comes into contact with the lawn grass while moving in the rearward direction. That is, the cutting portion201comes into contact with the lawn grass in an arrow B direction ofFIG.5B. In this case, since the cutting portion201and the cut portion g1of the lawn grass contact each other at an acute angle Θ2, resistance between the cutting portion201and the lawn grass is relatively large, and thus the cutting portion201is less likely to slip on the lawn grass. Therefore, the lawn grass after the cutting tends to be less likely to shift upward as compared with the case of cutting in the arrow A direction.

As a result, there is a case where there is a difference in height after the lawn mowing between a portion cut on the left half side and a portion cut on the right half side of the work machine W in the cut portion of the lawn grass. Therefore, the lawn grass may be cut to a height not intended by the user, which may affect the work efficiency of the work machine W. Therefore, for the purpose of further improving the efficiency and performance of the lawn mowing work by the work machine W, improvement of the driving mode of the working mechanism has been required in some cases.

Therefore, in the present embodiment, the control unit5performs the following processing to reduce the difference in height after the lawn mowing.FIG.6is a flowchart illustrating a processing example of the control unit5. For example, this flowchart is started when the control unit5receives a signal for starting the working unit2received by the work operation unit62. To be noted, S1corresponds to the processing of the rotation speed controller511, and S2and subsequent steps correspond to the processing of the torque controller512.

In S1, the rotation speed controller511performs rotation speed control. Specifically, on the basis of the difference between a predetermined rotation speed command value and the actual rotation speed of the motor M acquired on the basis of a detection result of the rotation sensor82, the torque command value is determined so that the actual rotation speed of the motor M becomes closer to the rotation speed command value. To be noted, the predetermined rotation speed command value may be, for example, a fixed value determined according to the type of the work machine W. When a work mode or the like can be selected by the operation unit6, a value determined according to the mode may be used.

In S2, the torque controller512acquires the rotational position of the rotary member20. Specifically, the torque controller512acquires the rotational position on the basis of the detection result of the rotation sensor82.

In S3, the torque controller512checks whether or not the position of the rotary member20is within a predetermined range, proceeds to S4in the case where the position is within the predetermined range, and proceeds to S5in the case where the position is outside the predetermined range. In the present embodiment, the predetermined range is a range in which one of the cutting portions201aand201bis located between 270° and 360°.

In S4, the torque controller512sets the torque command value to a value different from a value based on the rotation speed control. In the present embodiment, the torque controller512sets the torque command value to be higher than a predetermined value. In contrast, in S5, the torque controller512sets the torque command value to a value based on the rotation speed control.

In S6, the torque controller512converts the torque command value set in S4or S5into a direct current command value, and outputs the direct current command value to the inverter circuit52as a drive signal. For example, the torque controller512performs the change with reference to a torque command value-current command value conversion table stored in the memory of the MCU51.

FIG.7is a graph illustrating a relationship between the torque command value set by the torque controller and the rotational position of the rotary member20of a case where the flowchart ofFIG.6is executed. The horizontal axis represents the rotation angle of the cutting portion201a. The torque controller512is controlled such that the torque command value is higher than the predetermined value when the cutting portion201is located in the range R2, which is from 90° to 180°, and the range R4. Here, when the cutting portion201ais located in the range R2, the cutting portion201bis located in the range R4. Therefore, the torque controller512executes control so that the torque command value increases when either the cutting portion201aor the cutting portion201bis located in the range R4.

As a result, the torque command value while either the cutting portion201aor the cutting portion201bis moving in the forward direction and cutting lawn grass becomes higher than the predetermined value. Therefore, since the rotation speed of the rotary member20at the rotational position where the height of the lawn grass after cutting is likely to shift upward increases, the height of the lawn grass to be cut becomes less likely to shift upward, and the difference in the height of the lawn grass after the lawn mowing becomes less likely to occur. That is, the work machine W can cut lawn grass at a more similar height. Therefore, by the above control, it is possible to improve the doneness of lawn mowing by the work machine W, in other words, the work performance of the work machine W.

To be noted, although the control unit5controls the motor M so that the value of the torque of the motor M partially varies during one rotation of the rotary member20in the present embodiment, the motor M may be controlled so that the rotation speed of the motor M partially varies during one rotation. Specifically, the control unit5may control the motor M so that the rotation speed of the motor M increases in the state where the cutting height of the lawn grass is likely to shift upward. That is, the control unit5may control the motor M so that the output of the motor M increases during one rotation of the rotary member20. By adopting such control, the relative rotation speed of the rotary member20in a state where the cutting height of the lawn grass is likely to shifted upward is increased as compared with a case where such control is not adopted, and thus a difference in the height of the lawn grass after lawn mowing is less likely to occur. It is therefore possible to improve the work performance of the work machine W.

To be noted, although the predetermined range in which the torque command value is increased is a range in which one of the cutting portions201aand201bis located in the range R4in the processing example described above, the predetermined range of the angle for changing the output can be changed. In one embodiment, the predetermined range may be at least a part of a range in which either one of the cutting portions201aand201bmoves in the forward direction. Specifically, the predetermined range may be a range in which either one of the cutting portions201aand201bis located in a range from 270° to 300°. By increasing the output of the motor M in only a range where the vector component of the movement speed of the cutting portion201in the forward direction is larger, it is possible to suppress the power consumption from the driving of the motor M while improving the work performance.

To be noted, although the predetermined range is set in consideration of improvement of the work performance of the work machine W in the processing example described above, the predetermined range may be set in consideration of power saving of the work machine W. In the case where the working unit2cuts lawn grass while the work machine W moves forward, the cutting portion201cuts most of the lawn grass when moving in the range R1and the range R4which are ranges on the front side of the rotation shaft20a. Therefore, when the cutting portion201moves in the range R2and the range R3, the cutting portion201passes a part where most of the lawn grass has been already cut, and therefore it is less necessary to increase the torque as the case where the cutting portion moves in the ranges R1and R4. Therefore, the predetermined range may be set such that either one of the cutting portions201aand201bis on the forward side of the rotation shaft20aof the rotary member20, that is, at least a part of the range R4and the range R1. For example, in the case of a single blade, when the blade passes through the range R2and the range R3, the other blades do not pass through the range R4and the range R1, and therefore even if the torque or the speed is not increased in the range R2and the range R3, the doneness is less affected. Therefore, the power saving of the work machine W can be achieved by setting at least a part of the range R4and the range R1to a predetermined range. Furthermore, in the range R1, since the cutting position of the lawn grass is less likely to shift upward than in the range R4, it is not necessary to increase the torque or the rotation speed as much as in the range R4. Therefore, by setting at least a part of the range R4to a predetermined range, it is possible to more effectively achieve power saving of the work machine W.

Although the control unit5controls the motor M so that the output of the motor M increases in a predetermined range in the processing example described above, the control unit5may control the motor M so that the output of the motor M decreases in a predetermined range. As an example, the control unit5may control the motor M so that the torque command value decreases while either one of the cutting portions201aand201bis located in the range R1.

In the above processing example, an example has been described in which the control unit5controls the motor M so that the torque command value becomes a different value in consideration of the doneness of the lawn mowing. However, the control unit5may control the motor M so that the torque command value becomes a different value in consideration of the urging direction of the lawn grass by the fan202.

In the present embodiment, lawn grass cut by the airflow generated by the fan202is introduced into the collection unit3at the rear via the discharge port301. Therefore, when the airflow toward the discharge port301to the collection unit3increases, lawn grass is more effectively introduced into the collection unit3. Here, as a condition for increasing the airflow toward the discharge port301, it is conceivable to increase the rotational output of the rotary member20when either one of the fans202aand202bis moving in a direction approaching the discharge port301. As an example, it is conceivable to increase the output of the rotary member20when either one of the fans202aand202brotates in a range of 0° to 180°, a range of 90° to 180°, or a range of 45° to 135°. Therefore, by controlling the torque command value of the motor M to be higher than a specified value in these ranges, the control unit5can more effectively urge the lawn grass toward the collection unit3, and the collection efficiency of the lawn grass can be improved. To be noted, when the discharge port301is formed in the range W2in the width direction illustrated inFIG.2, that is, when the discharge port is formed in the range on the left half side in the housing in plan view, the rotary member20may be rotated in a direction opposite to the rotation direction illustrated inFIG.2. In this case, the output of the rotary member20may be increased in at least a part of the range R3and the range R4in which either one of the fans202aand202bapproaches the discharge port301.

In addition, the range may be determined in consideration of both the doneness of lawn mowing and the collection efficiency of the lawn grass. For example, the control unit5may increase the torque in the case where either one of the cutting portions201aand201bis located in a range of 270° to 300°, and may increase the torque in the case where either one of the fans202aand202bis located in a range of 60° to 90°. In this case, the amount of increase in torque may be made different between the case of increasing the torque on the basis of the position of the cutting portion201and the case of increasing the torque on the basis of the position of the fan202.

Other Embodiments

Although the fan202and the cutting portion201are provided integrally with the rotary member20in the embodiment described above, these may be provided separately.FIG.8is a schematic view of a working unit92according to another embodiment, and is a diagram illustrating an example in which a cutting portion9201is provided in a rotary member920and a fan9212is provided in a rotary member921. In this manner, the cutting portion9201and the fan9212may be rotatably provided by the motor M.

In addition, in such a case, the angle between the cutting portion9201and the fan9212may be deviated from each other. Furthermore, these angles may be deviated such that the timing at which the torque is desired to be increased for the cutting by the cutting portion9201coincides with the timing at which the torque is desired to be increased for the collection of the lawn grass by the fan9212.

For example, it is assumed that the torque is increased in the case where either one of cutting portions9201aand9201bis located in the range R4and in the case where either one of fans9212aand9212bis located within a range from 45° to 135°. In this case, the fan9202amay be arranged to be shifted by 45° to the side opposite to the rotational direction with respect to the cutting portion9201a. As a result, since the timing at which the torque is desired to be increased for the cutting by the cutting portion9201and the timing at which the torque is desired to be increased for the collection of the lawn grass by the fan9212coincide with each other, it is possible to more effectively improve both the doneness and the collection efficiency of the lawn grass.

In addition, in the above embodiment, a metal material such as iron or aluminum is exemplified as the material of the rotary member20constituting the cutting portion201. However, a lighter rotary member20may be adopted. That is, a lighter blade may be adopted as the cutting portion201.

In the case where the drive control of the motor M is performed only by the above-described rotation speed control, a metal material having a relatively large moment of inertia has been used as the material of the rotary member20in order to stabilize the rotation speed. However, since the current command value of the motor M can be directly controlled by using the vector control described above, the behavior of the rotary member20can be stably maintained even when a blade made of a lighter material is used.

As an example, a configuration in which a plate-shaped resin blade as a cutting portion is extended from a disk-shaped rotary member or a configuration in which a so-called nylon cord is attached to a disk-shaped rotary member can also be employed. By using such a blade having a smaller moment of inertia, the influence of inertia in the control can be reduced, so that more accurate drive control can be executed. In addition, since the weight of the rotary member itself is reduced, the power required for rotation is reduced, so that the power consumption related to the driving of the motor M can be reduced.

In addition, as another aspect of the cutting portion201, a disk blade or the like in which the cutting portion is provided on a disk-shaped rotary member to be spaced apart in the circumferential direction may be used. In addition, the number of blades is not limited to this, and one blade or three blades may be used.

Although the cut lawn grass is collected by the collection unit3in the embodiment described above, it can be also employed for a so-called side discharge type lawn mower that discharges the lawn to the outside of the work machine W. Also in this case, the torque may be increased in a region urged toward the discharge port. As a result, since the output of the rotary member20is controlled so that the urging force toward the outside of the work machine W increases, it is possible to suppress the discharged lawn grass forming a lump.

Although the walking lawn mower has been described as an example in the embodiment described above, the configuration according to the above-described embodiment can also be applied to a riding lawn mower, a robot lawn mower, and the like.

In addition, the present invention is applicable not only to lawn mowers but also to other work machines such as snow blowers and cultivators. For example, in a blower that urges and blows off snow scraped up by an auger in a predetermined direction in a snow blower, the torque may be increased at a position urged in the snow projection direction. As a result, it is possible to suppress a case where snow is not sufficiently blown off by the blower and the blown snow is agglomerated in the vicinity of the work machine.

Summary of Embodiments

The above embodiment discloses at least the following work machine and program.1. A work machine (for example, W) of the above embodiments comprises:a drive source(for example, M);a working unit (for example,2) that includes a rotary member (for example,20) rotated by the drive source and performs a predetermined work by rotation of the rotary member; anda control unit (for example,5, S3, S4) that controls the drive source so that output of the rotary member partially takes different values in one rotation of the rotary member.

According to this embodiment, it is possible to provide a technique advantageous for further improvement in efficiency, performance, and the like of the work machine.2. According to the above embodiments,the rotary member includes a cutting portion (for example,201) capable of cutting a lawn grass, andthe working unit includes a cover portion (for example,22) that covers the rotary member at least on a forward side in a traveling direction of the work machine.

According to this embodiment, since the output of the rotary member when mowing the lawn pushed down by the cover portion partially varies within one rotation, and thus the length of the cut lawn grass can be changed.3. According to the above embodiments, wherein the control unit controls the drive source so that the output is higher in at least a part of a range in which the cutting portion moves toward the forward side than in a part different from the at least a part.

According to this embodiment, since the output of the rotary member increases in an area where the resistance generated between the lawn grass and the cutting portion is relatively small, the cutting portion is less likely to slip with respect to the lawn grass when cutting the lawn grass. Therefore, the heights of the cut lawn grass can be further equalized.4. According to the above embodiments, the control unit controls the drive source so that the output is higher in at least a part of a range in which the cutting portion is located on the forward side as compared with a rotation shaft of the rotary member than in a part different from the at least a part.

According to this embodiment, since the output is increased in an area where the amount of lawn cut by the cutting portion is larger, it is possible to improve work efficiency and reduce power consumption at the same time.5. According to the above embodiments, the control unit controls the drive source so that the output is lower in at least a part of a range in which the cutting portion moves toward a rear side in the traveling direction than in a part different from the at least a part.

According to this embodiment, since the output of the rotary member is decreases in an area where the resistance generated between the cutting portion and the lawn grass is large and the cutting portion is less likely to slip with respect to the lawn grass, power consumption can be reduced.6. According to the above embodiments,the rotary member includes a plurality of the cutting portions different in a circumferential direction, andthe control unit controls the drive source so that the output in a case where at least one of the plurality of the cutting portions is located in the at least a part is a different value from the output in a case where none of the plurality of the cutting portions is in the at least a part.

According to this embodiment, it is possible to improve work efficiency in a case where a plurality of cutting portions are provided.7. According to the above embodiments, the rotary member includes an urging portion (for example,202) that urges a target object by rotation of the rotary member.

According to this embodiment, since the output of the rotary member having the urging portion partially varies in one rotation, it is possible to vary the urging force on the target object according to the rotational position.8. According to the above embodiments,the working unit further includes a cutting portion (for example,201) capable of cutting a lawn grass, and a cover portion (for example,22) that covers the rotary member,a discharge port (for example,301) through which the lawn grass that is the target object and is cut by the cutting portion is discharged from a region covered by the cover portion is formed in the cover portion, andthe control unit controls the drive source so that the output of the rotary member is high in at least a part of a range where the urging portion urges the lawn grass toward the discharge port in one rotation of the rotary member.

According to this embodiment, since the urging force on the lawn grass in the direction toward the discharge port increases, the lawn grass can be discharged more effectively.9. According to the above embodiments,the rotary member includes an extending portion (for example,20b) extending from a rotation shaft of the rotary member in a radial direction,the urging portion and the cutting portion are provided in the extending portion,the discharge port is provided on a rear side of the cover portion in a traveling direction, andthe control unit controls the drive source so that, in one rotation of the rotary member, the output of the rotary member is high in at least a part of a range in which the urging portion urges the lawn grass toward the discharge port and the extending portion is located more on a forward side than the rotation shaft.

According to this embodiment, power consumption can be reduced by suppressing output in an area where the amount of lawn cut by the cutting portion is small while effectively discharging the lawn grass.10. According to the above embodiments,the discharge port is formed within a range in a width direction in which the urging portion advances toward the discharge port.

According to this embodiment, it is possible to suppress urging of the lawn grass from the discharge port side toward the cover portion side.11. According to the above embodiments, discharge port is formed so that the target object is discharged to an outside of the work machine.

According to this embodiment, since the output of the rotary member is controlled such that the urging force toward the outside of the work machine increases, it is possible to suppress formation of a lump of the discharged lawn grass.12. A non-transitory computer-readable storage medium of the above embodiments stores a program for causing a computer of a work machine (for example, W) including a drive source (for example, M) and a working unit (for example,2) that includes a rotary member (for example,20) rotated by the drive source and performs a predetermined work by rotation of the rotary member, to function as:a control unit (for example, S3, S4) that controls the drive source so that output of the rotary member partially takes different values in one rotation of the rotary member.

According to this embodiment, it is possible to provide a technique advantageous for further improvement in efficiency, performance, and the like of the work machine.13. According to the above embodiments,the rotary member includes a cutting portion (for example,201) capable of cutting a lawn grass, andthe working unit includes a cover portion (for example,22) that covers the rotary member on a forward side in a traveling direction of the work machine.

According to this embodiment, since the output of the rotary member when mowing the lawn pushed down by the cover portion partially varies within one rotation, and thus the length of the cut lawn grass can be changed.14. According to the above embodiments, the control unit controls the drive source so that the output is higher in at least a part of a range in which the cutting portion moves toward the forward side than in a part different from the at least a part.

According to this embodiment, since the output of the rotary member increases in an area where the resistance generated between the lawn grass and the cutting portion is relatively small, the cutting portion is less likely to slip with respect to the lawn grass when cutting the lawn grass. Therefore, the heights of the cut lawn grass can be further equalized.15. According to the above embodiments, the control unit controls the drive source so that the output is higher in at least a part of a range in which the cutting portion is located on the forward side as compared with a rotation shaft of the rotary member than in a part different from the at least a part.

According to this embodiment, since the output is increased in an area where the amount of lawn cut by the cutting portion is larger, it is possible to improve work efficiency and reduce power consumption at the same time.16. According to the above embodiments, the control unit controls the drive source so that the output is lower in at least a part of a range in which the cutting portion moves toward a rear side in the traveling direction than in a part different from the at least a part.

According to this embodiment, since the output of the rotary member is decreases in an area where the resistance generated between the cutting portion and the lawn grass is large and the cutting portion is less likely to slip with respect to the lawn grass, power consumption can be reduced.17. According to the above embodiments,the rotary member includes a plurality of the cutting portions different in a circumferential direction, andthe control unit controls the drive source so that the output in a case where at least one of the plurality of the cutting portions is located in the at least a part is a different value from the output in a case where none of the plurality of the cutting portions is in the at least a part.

According to this embodiment, it is possible to improve work efficiency in a case where a plurality of cutting portions are provided.18. According to the above embodiments, the rotary member includes an urging portion (for example,202) that urges a target object by rotation of the rotary member.

According to this embodiment, since the output of the rotary member having the urging portion partially varies in one rotation, it is possible to vary the urging force on the target object according to the rotational position.19. According to the above embodiments,the working unit further includes a cutting portion (for example,202) capable of cutting a lawn grass, and a cover portion (for example,22) that covers the rotary member,a discharge port through which the lawn grass that is the target object and is cut by the cutting portion is discharged from a region covered by the cover portion is formed in the cover portion, andthe control unit controls the drive source so that the output of the rotary member is high in at least a part of a range where the urging portion urges the lawn grass toward the discharge port in one rotation of the rotary member.

According to this embodiment, since the urging force on the lawn grass in the direction toward the discharge port increases, the lawn grass can be discharged more effectively.20. According to the above embodiments,the discharge port is provided on a rear side of the cover portion in a traveling direction, andthe part is a part in which the urging portion moves in the rear side.

According to this embodiment, power consumption can be reduced by suppressing output in an area where the amount of lawn cut by the cutting portion is small while effectively discharging the lawn grass.21. According to the above embodiments,the discharge port is formed within a range in a width direction in which the urging portion advances toward the discharge port.

According to this embodiment, it is possible to suppress the lawn grass being biased from the discharge port side toward the cover portion side.22. According to the above embodiments, the discharge port is formed so that the target object is discharged to an outside of the work machine.

According to this embodiment, since the output of the rotary member is controlled such that the urging force toward the outside of the work machine increases, it is possible to suppress formation of a lump of the discharged lawn grass.

The invention is not limited to the foregoing embodiments, and various variations/changes are possible within the spirit of the invention.