Rotary grass cutting blade, mounting base, knife part, and grass cutter

Abstract

The present invention provides a rotary grass cutting blade, mounting base, knife section, and grass cutter that can accommodate at least three different uses or methods of use. [Solution] The grass trimmer 1 has a mounting base 61 and a knife portion 62 with a blade portion, and a rotary grass trimming blade 6 has a structure that allows for the selective application of either a first mounting shaft 67 having a cylindrical portion around its circumference, or a second mounting shaft 68 having a polygonal prism portion or a convex portion around its circumference, for connecting these. The rotatably mounted mounting base 61 has a first mounting hole 613 formed near its peripheral edge for attaching the knife portion 62. The knife portion 62 has a second mounting hole formed on the base side that corresponds in shape to the first mounting hole 613. The first and second mounting holes are open to a size that allows the inserted first mounting shaft 67 to rotate around its axis, and recesses are formed on the inner surface of the holes that engage with the convex portion of the inserted second mounting shaft 68 to lock it so that it cannot rotate around its axis.

Description

Technical Field

[0001] The present invention relates to a rotary grass cutting blade, a mounting base, a knife part, and a lawn mower. More specifically, the present invention relates to a rotary grass cutting blade, a mounting base, a knife part, and a lawn mower that have a simple structure and can correspond to at least three types of uses or usage methods.

Background Art

[0002] Conventionally, lawn mowers equipped with rotary grass cutting blades have been manufactured and sold. As the blade part of the rotary grass cutting blade, there are those that are fixedly attached without swinging during rotation, such as "bar knives," and those that are fixedly attached so as to be swingable during rotation, such as "free knives," with respect to the mounting base that becomes the rotating part. For example, the one described in Patent Document 1 below has been proposed as the above-mentioned bar knife, and the one described in Patent Document 2 below (particularly in paragraphs 0045 and 0046 of the specification and FIG. 6) has been proposed as the above-mentioned free knife.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

[0004]

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Since the above-mentioned bar knife is a fixed blade and the knife does not escape and cuts plants, it has the merit that the cut trace is beautifully finished. On the other hand, compared with the free knife, there are many scattered objects, and since it is a fixed blade, the impact when colliding with an obstacle is transmitted to the knife drive system, and there is a demerit that the risk of breakage is high.

[0006] In contrast, the aforementioned free knife has advantages over bar knives, such as producing less flying debris, less wear on the blade per unit area, and less damage to the machine and obstacles when it hits an obstacle, as the blade moves in the opposite direction of rotation (oscillates) to escape. However, it also has disadvantages compared to bar knives, such as having more parts and producing a less clean cut.

[0007] Generally, commercially available brush cutters are equipped with a cutting section that has either a bar knife or a free knife, as mentioned above. In order to utilize the advantages of each type of knife in various weeding work sites, it was necessary to change the brush cutter itself.

[0008] This invention was conceived in view of the above points, and aims to provide a rotary grass cutting blade, mounting base, knife part, and grass cutter that have a simple structure and can accommodate at least three types of uses or methods of use. [Means for solving the problem]

[0009] To achieve the above objective, the rotary grass cutting blade of the present invention comprises a mounting base and a knife portion, the mounting base being rotatably mounted by receiving power in its central portion and having a first mounting hole formed near its peripheral edge for attaching the knife portion, the knife portion having a predetermined length and / or having a blade portion on its tip and / or side, and having a second mounting hole formed on the base side having a shape corresponding to the first mounting hole, the mounting base and the knife portion being selected according to the application with the first and second mounting holes overlapping, The structure is designed to be mounted by inserting either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft that is polygonal in shape with multiple corners around its circumference or has a protrusion provided in the direction of the long axis of the circumferential surface. The first and second mounting holes are sized to allow rotation around the axis when the first mounting shaft is inserted, and have recesses formed on their inner surfaces that engage with the corners or protrusions to lock the second mounting shaft so that it cannot rotate around its axis when it is inserted.

[0010] The rotary grass cutting blade of the present invention has a mounting base that is powered and rotatable in the central part, so that it rotates itself, and the knife part attached near the peripheral part also rotates in conjunction with its rotation, allowing weeding work to be performed by the blade part of the rotating knife. Furthermore, due to the structure described above, the rotary grass cutting blade can be selectively fitted with either a first mounting shaft or a second mounting shaft depending on the application.

[0011] More specifically, when the first mounting shaft is applied, the knife portion is mounted so that its tip can swing along the rotational direction of the mounting base, with the second mounting hole as the pivot point (hereinafter sometimes referred to as the "free knife configuration"). This allows the knife portion to reduce or deflect the impact by moving in the rotational direction when the blade portion comes into contact with a hard object, thereby suppressing damage to the blade portion, the knife portion, the mounting base, and the brush cutter drive system, and further suppressing damage to the object that the knife portion collides with.

[0012] Furthermore, the retracted knife section returns to its original position due to centrifugal force, allowing weeding work to continue without stopping the machine. In addition, compared to bar-knife type mowing blades, there is less flying debris and less wear on the blade per unit area.

[0013] On the other hand, when the second mounting shaft is applied, the knife section is fixed so as not to rotate around the second mounting hole. This allows for powerful cutting, similar to a bar-knife type mowing blade, when the target of cutting is sticky grass or grass with somewhat thick stems. Furthermore, since the knife section does not move (retract) when it hits the target of cutting, a clean cut is achieved.

[0014] When the second mounting shaft is applied, in addition to the configuration in which the longitudinal center line of the knife portion is aligned with the extension of the line connecting the rotation center of the mounting base to the first mounting hole (hereinafter sometimes referred to as the "straight blade configuration"), depending on the shape of the corners or protrusions of the first mounting hole and the second mounting shaft, it is also possible to select a configuration in which the longitudinal center line of the knife portion is inclined at a predetermined angle with respect to the extension of the line connecting the rotation center of the mounting base to the first mounting hole, in either the forward or reverse rotation direction of the mounting base (hereinafter sometimes referred to as the "inclined blade configuration").

[0015] The straight blade configuration or the inclined blade configuration can be appropriately selected according to the characteristics of the grass and trees to be cut, as described above. Furthermore, when the straight blade configuration is selected, the cutting range of the rotary grass cutting blade can be set to the maximum, and when the inclined blade configuration is selected, the cutting range can be set to be narrower (smaller) than the cutting range with the straight blade configuration. In other words, the cutting range can be adjusted by selecting the straight blade configuration or the inclined blade configuration.

[0016] Thus, the rotary grass cutting blade of the present invention, while being a simple rotary grass cutting blade, can accommodate at least three types of applications or methods of use (the free knife configuration, straight blade configuration, and inclined blade configuration described above). Furthermore, the first mounting hole formed in the mounting base may be in multiple locations rather than just one, and accordingly, the knife portion may be provided in multiple locations rather than just one.

[0017] The meanings of the expressions used in the description of this invention are as follows:

[0018] The recesses formed in the first and second mounting holes correspond to the number and shape of the corners of the second mounting shaft when the second mounting shaft has a polygonal prism shape, and are provided in a shape and number that perfectly accommodates the protrusions when the second mounting shaft has protrusions provided in the direction of the long axis of the shaft surface. Furthermore, the expression "shape" used to describe the second mounting hole includes not only the shape of the hole but also its size.

[0019] In the case where the second mounting shaft has a polygonal prism shape, the first and second mounting holes are not particularly limited as long as they are triangular or greater. In the inclined blade configuration described above, it is preferable that the number of sides be pentagonal or greater to allow for fine angle adjustment. However, if there are too many corners, the processing becomes complicated and manufacturing costs increase, so it is preferable that the number of sides be hexagonal or less.

[0020] The expression "near the peripheral edge" used to describe the mounting base is used to mean not only the peripheral edge of the mounting base, but also the inner region of the mounting base that is close to the peripheral edge.

[0021] The expression "tip side and / or side" used to describe the knife part includes both cases where it is "tip side or side" and cases where it is "tip side and side". Furthermore, the expression "predetermined length" used to describe the knife part can be suitably set depending on the size of the rotary grass cutting blade and the target to be cut, but the blade portion is at least within the range of 3 cm to 50 cm. A length of less than 3 cm is undesirable because it reduces the cutting area, while a length exceeding 50 cm is undesirable because it makes it difficult to perform detailed weeding when there are obstacles near the target to be cut.

[0022] The cylindrical portion on the circumference of the first mounting shaft may be provided along the entire length of the shaft, or it may be provided in a part of the shaft. Similarly, the polygonal prism portion or convex portion on the circumference of the second mounting shaft may be provided along the entire length of the shaft, or it may be provided in a part of the shaft.

[0023] The term "recess" used to describe the first and second mounting holes includes not only those that can engage with the protrusions on the circumferential surface of the second mounting shaft, but also corner recesses (sometimes referred to as "corners") that can engage with the corners on the circumferential surface of the second mounting shaft. Furthermore, the expression "overlapping state" regarding the first and second mounting holes can also be rephrased as "a state in communication" between the first and second mounting holes.

[0024] Further, the rotary grass cutting blade described above further includes a first attachment shaft body having a cylindrical portion around the axis, and a second attachment shaft body having a polygonal column shape with a plurality of corners around the axis or having a convex portion provided in the longitudinal axis direction of the circumferential surface of the axis.

[0025] By including the first attachment shaft body and the second attachment shaft body, the rotary grass cutting blade of this aspect can be selectively applied according to the application. When the first attachment shaft body is applied, the knife portion can be attached to the attachment base in a free knife mode. When the second attachment shaft body is applied, the knife portion can be fixed to the attachment base in a non-rotatable manner in either a straight blade mode or an inclined blade mode.

[0026] In addition, in the rotary grass cutting blade described above, the first attachment shaft body has a male thread formed in the region in the axial direction of the shaft tip, and a cylindrical portion is formed in the intermediate portion excluding the male thread forming region. The second attachment shaft body has a male thread formed in the region in the axial direction of the shaft tip, and a spline portion is formed in the intermediate portion excluding the male thread forming region. The first attachment hole and the second attachment hole are formed with spline receiving grooves on the inner surface of the holes, and the cylindrical voids formed on the top surfaces of each ridge portion between the spline receiving grooves are set to a size that can rotatably receive the cylindrical portion of the first attachment shaft body.

[0027] In the rotary grass cutting blade of this aspect, since the first attachment shaft body and the second attachment shaft body have the male threads described above, they can be applied to the female threads formed on nuts, attachment bases, etc. and tightened to attach the knife portion to the attachment base.

[0028] In the rotary grass cutting blade of this aspect, since the spline portion is formed on the second attachment shaft body, and the spline receiving grooves are formed on the inner surfaces of the first attachment hole and the second attachment hole, the spline portion and the spline receiving groove engage with each other, and the knife portion becomes non-rotatable and is firmly fixed.

[0029] In this embodiment, the rotary grass cutting blade has a cylindrical portion formed on the first mounting shaft, and the aforementioned cylindrical gaps are formed in the first and second mounting holes. As a result, the cylindrical portion can rotate smoothly with minimal rattle within the cylindrical gap when fitted into the first and second mounting holes, meaning that the knife portion (the tip) can be mounted in a state where it can swing along the rotational direction of the mounting base.

[0030] The term "spline portion" used to describe the second mounting shaft includes not only shapes like a typical spline shaft, but also shapes such as a star shape in cross-section, and is used to mean shapes in which protruding parts like corners and recessed parts like grooves or indented corners are continuous in cross-section.

[0031] The first and second mounting shafts may be various bolts or screws with a male thread on one end, in which case a cylindrical portion or spline portion is provided in the region between the head and the male thread; or they may be bolts with male threads on both ends, in which case a cylindrical portion or spline portion is provided in the region between both male threads.

[0032] Furthermore, the aforementioned rotary grass cutting blade has a pair of blades, with the first blade positioned on one side of the mounting base and the second blade positioned on the other side of the mounting base. The blade is mounted by inserting either the first or second mounting shaft, which is selectively applied depending on the application, with the first mounting hole of the mounting base, the second mounting hole of the first blade, and the second mounting hole of the second blade overlapping.

[0033] The rotary grass cutting blade of this embodiment, due to the structure described above, for example, when the mounting base is parallel to the ground, has a two-blade structure in which the first knife and the second knife are positioned vertically apart, enabling more efficient and even weeding work. Note that the "state in which the first mounting hole of the mounting base, the second mounting hole of the first knife, and the second mounting hole of the second knife overlap" can also be rephrased as the state in which the first mounting hole of the mounting base, the second mounting hole of the first knife, and the second mounting hole of the second knife are "connected".

[0034] Furthermore, with the rotary grass cutting blade of this embodiment, when applying the second mounting shaft, it is also possible to select an embodiment in which the first knife and the second knife are parallel (hereinafter sometimes referred to as the "parallel embodiment"; the parallel embodiment includes the straight blade embodiment or the inclined blade embodiment described above) and an embodiment in which the tips of the first knife and the second knife are opened to form a V shape (hereinafter sometimes referred to as the "V-shaped embodiment"; the V-shaped embodiment is an example of the inclined blade embodiment described above).

[0035] When the first and second knives form a V-shape, the first and second knives of one knife section strike the target to be cut twice at different timings, and the cutting is performed by the first and second knives which are positioned apart vertically. As a result, even though it is a single knife section, the work efficiency is further improved and weeding work can be performed with evenly spaced cuts.

[0036] Furthermore, if there are many recesses in the first and second mounting holes and many corners or protrusions on the second mounting shaft, it becomes possible to finely adjust the angle formed by the bases of the first and second knives (the degree of opening of each knife tip) in the inclined blade configuration described above. Moreover, if spline receiving grooves are formed in the first and second mounting holes and a spline portion is formed on the second mounting shaft, this angle adjustment can be made even more precise.

[0037] To achieve the above objective, the mounting base of the present invention is used for a rotary grass cutting blade, and the main body is rotatably mounted in the central part by receiving power, and a first mounting hole is formed in the base part that corresponds in shape to the second mounting hole for attaching a grass cutting knife part having a predetermined length and a blade part on the tip side and / or side, with a second mounting hole formed on the base side, to which the knife part to be attached is attached to the main body by inserting either a first mounting shaft having a cylindrical part on its circumference, or a second mounting shaft having a polygonal prism shape with multiple corners on its circumference or a convex part provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the first mounting hole and the second mounting hole overlapping, and the first mounting hole is shaped to open to a size that allows rotation around the axis when the first mounting shaft is inserted, and a recess is formed on the inner surface of the hole that can engage with the corner or the convex part to lock it so that it cannot rotate around the axis when the second mounting shaft is inserted.

[0038] The mounting base of the present invention is used for rotary grass cutting blades. Due to the structure described above, the main body of the mounting base can be attached to the vicinity of the peripheral edge of the main body via the first mounting hole. Furthermore, since the main body is provided to be rotatable by receiving power in its central part, it rotates itself, and the knife part attached to the vicinity of the peripheral edge also rotates with its rotation, allowing weeding work to be performed by the blade portion of the rotating knife part.

[0039] Furthermore, the mounting base, due to its structure as described above, allows for the insertion of either a first or second mounting shaft, which can be selected and applied according to the application, into the first mounting hole.

[0040] More specifically, the mounting base can be fitted with the first mounting shaft to which the aforementioned knife section can be attached. In this case, the aforementioned knife section is mounted in such a manner that its tip can swing along the rotational direction of the mounting base, with the second mounting hole as the pivot point. As a result, when the knife section collides with a hard object, damage to the blade, the knife section, the mounting base, and the brush cutter drive system can be suppressed, and furthermore, damage to the object that the knife section collides with can be suppressed.

[0041] Furthermore, the mounting base can be fitted with the second mounting shaft to attach the aforementioned knife section. In this case, the aforementioned knife section is fixed so as not to rotate around the second mounting hole. As a result, the knife section can cut with strong force, similar to a bar knife structured grass cutting blade, and does not move away (reverse) when it hits the target to be cut, resulting in a clean cut.

[0042] In addition, the mounting base of the present invention allows for the selection of either a straight blade configuration or an inclined blade configuration when attaching the aforementioned knife portion by applying the second mounting shaft thereto. Consequently, a rotary grass cutting blade employing this mounting base can accommodate at least three different applications or methods of use, despite being a simple rotary grass cutting blade. The meaning of the expressions used in the description of the present invention is as previously stated, and therefore no further explanation is provided.

[0043] To achieve the above objective, the knife portion of the present invention is used by being attached to the mounting base of a rotary grass cutting blade, and has a predetermined length, with a blade portion provided on the tip side and / or the side, and a second mounting hole is formed on the base side that corresponds in shape to a first mounting hole formed near the peripheral edge of the mounting base, and the knife portion is attached by inserting either a first mounting shaft having a cylindrical portion on its circumference, or a second mounting shaft that is polygonal prism-shaped with multiple corners on its circumference or has a protrusion provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the second mounting hole and the first mounting hole of the mounting base overlapping, and the second mounting hole is open to a size that allows rotation around the axis when the first mounting shaft is inserted, and has a recess formed on the inner surface of the hole that can engage with the corner or protrusion to lock the second mounting shaft so that it cannot rotate around the axis when the second mounting shaft is inserted.

[0044] The knife portion of the present invention is used in rotary grass cutting blades. Due to the structure described above, the knife portion can be attached to the vicinity of the peripheral edge of the mounting base via the second mounting hole. Furthermore, the knife portion attached to the vicinity of the peripheral edge of the mounting base rotates in conjunction with the rotation of the mounting base, and weeding work can be performed by the blade portion of the rotating knife portion.

[0045] Furthermore, due to the structure described above, the knife section allows for the insertion of either a first or second mounting shaft, which can be selected and applied according to the application, into the first mounting hole.

[0046] More specifically, the knife section can be attached to the aforementioned mounting base by applying the first mounting shaft. In this case, the knife section is mounted in such a manner that its tip can swing along the rotational direction of the mounting base, with the second mounting hole as the pivot point. As a result, when the knife section collides with a hard object, damage to the blade, the knife section, the mounting base, and the brush cutter drive system can be suppressed, and furthermore, damage to the object that the knife section collides with can be suppressed.

[0047] Furthermore, the knife section can be fitted with the aforementioned mounting base by applying the second mounting shaft. In this case, the knife section is fixed so as not to rotate around the second mounting hole. As a result, the knife section can cut with strong force, similar to a bar knife structure, and does not move (receive backward) when it hits the target to be cut, resulting in a clean cut.

[0048] In addition, the knife portion of the present invention allows for the selection of either a straight blade configuration or an inclined blade configuration when the second mounting shaft is applied to it and attached to the aforementioned mounting base. Consequently, a rotary grass cutting blade employing this knife portion can accommodate at least three different uses or methods of use, despite being a simple rotary grass cutting blade. The meaning of the expressions used in the description of the present invention is as previously stated, and therefore no further explanation is provided.

[0049] To achieve the above objective, the present invention comprises a grass trimmer body having a prime mover, and a rotary grass trimming blade having a mounting base and a knife portion provided on the grass trimmer body, wherein the central portion of the mounting base is connected to the prime mover and is rotatably mounted by receiving power from the prime mover, and a first mounting hole for attaching the knife portion is formed near the peripheral portion, the knife portion has a predetermined length, a blade portion is provided on the tip side and / or the side, and a second mounting hole with a shape corresponding to the first mounting hole is formed on the base side, and the mounting base and the knife portion are connected as The structure allows for the insertion and mounting of either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft having a polygonal prism shape with multiple corners around its circumference or a protrusion provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the first mounting hole and the second mounting hole overlapping. The first and second mounting holes are sized to allow rotation around the axis when the first mounting shaft is inserted, and have recesses formed on their inner surfaces that engage with the corners or protrusions to lock the second mounting shaft so that it cannot rotate around its axis when the second mounting shaft is inserted.

[0050] The grass trimmer of the present invention can perform weeding work using the rotary grass trimming blade section with the structure described above. The effects of each part are as follows.

[0051] A brush cutter can drive its rotary cutting blade using a prime mover located in the main body of the brush cutter. The term "brush cutter" is used to include both brush cutters and self-propelled brush cutters, and "self-propelled brush cutter" includes walking type, ride-on type, wirelessly operated type (e.g., radio-controlled type), robot type (e.g., one that performs work autonomously controlled by a program, etc.).

[0052] The rotary grass cutting blade is mounted so that its mounting base receives power in the central part and is rotatable. As a result of this rotation, the knife part attached near the periphery also rotates, allowing the rotating knife part to perform weeding. Furthermore, due to the aforementioned structure, the rotary grass cutting blade can be selectively fitted with either the first or second mounting shaft depending on the application.

[0053] When the first mounting shaft is applied, the knife section is mounted so that its tip can swing along the rotational direction of the mounting base, with the second mounting hole as the pivot point. As a result, when the knife section collides with a hard object, damage to the blade, the knife section, the mounting base, and the brush cutter drive system can be suppressed, and furthermore, damage to the object that the knife section collides with can be suppressed. In addition, the retracted knife section returns to its original position due to centrifugal force, so weeding work can be continued without stopping the machine. Furthermore, compared to brush cutter blades with a bar knife structure, there is less flying debris and less wear on the blade section per unit area.

[0054] When the second mounting shaft is applied, the knife section is fixed so as not to rotate around the second mounting hole. As a result, the knife section can cut with strong force, similar to a bar knife structure, and does not move away (reverse) when it hits the target, resulting in a clean cut.

[0055] In addition, the rotary grass cutting blade section allows for the selection of either a straight blade configuration or an inclined blade configuration when attaching the knife section to the aforementioned mounting base by applying the second mounting shaft, thus enabling it to accommodate at least three different applications or methods of use despite being a simple rotary grass cutting blade. The meaning of the expressions used in the description of this invention is as previously stated, and therefore no further explanation is provided.

[0056] In the specification and claims of this application, the aforementioned "prime mover" is preferably an engine or a motor, but is not limited thereto, and may be other known power sources. [Effects of the Invention]

[0057] The rotary grass cutting blade, mounting base, knife section, and grass cutter of the present invention, while being a simple rotary grass cutting blade, can accommodate at least three different applications or methods of use. [Brief explanation of the drawing]

[0058] [Figure 1] This is a lawnmower according to the present invention, where (a) is a perspective view taken from the upper left side of the machine body, and (b) is a perspective view taken from the lower front side of the machine body. [Figure 2] Figure 1 is a bottom view of the grass trimmer shown in Figure 1, omitting the illustration of the driving mechanism and other parts, and showing the periphery of the rotary grass trimming blade. [Figure 3] Figure 1 is a perspective view showing the structure of the rotary grass cutting blade of the present invention, applied to the grass trimmer shown in Figure 1, in an disassembled state. [Figure 4] Figure 3 shows the rotary grass cutting blade section, where (a) is a plan view of the rotary grass cutting blade section and (b) is a side view of the rotary grass cutting blade section taken from the longitudinal direction. [Figure 5] The image shows the knife portion of the present invention applied to a rotary grass cutting blade, where (a) is a plan view of the knife portion, (b) is a side view of the knife portion taken from the longitudinal direction, and (c) is a bottom view of the knife portion. [Figure 6]This is a perspective view showing the rotary grass cutting blade in a disassembled state, where (a) is the configuration with the first mounting shaft applied, and (b) is the configuration with the second mounting shaft applied. [Figure 7] (a) is an enlarged explanatory diagram showing the state in which the second mounting shaft is fitted into the first mounting hole of the mounting base and the second mounting hole of the first knife (second knife) in the configuration shown in Figure 6(b), and (b) is an enlarged explanatory diagram showing the state in which the first mounting shaft is fitted into the first mounting hole of the mounting base and the second mounting hole of the first knife (second knife) in the configuration shown in Figure 6(a). [Figure 8] The diagram shows the usage state (movement of the knife part) of the rotary grass cutting blade in an embodiment to which the first mounting shaft is applied. (a) is an explanatory diagram showing the movement of the knife part during normal rotation, and (b) is an explanatory diagram showing the movement of the knife part when it collides with a foreign object. [Figure 9] The diagram shows variations in how a knife section having a first knife and a second knife is attached to a rotary grass cutting blade by applying a second mounting shaft. (a) is an explanatory diagram showing an arrangement where the first knife and the second knife overlap in a plan view, and (b) is an explanatory diagram showing an arrangement where the first knife and the second knife do not overlap in a plan view. [Figure 10] This is a comparative explanatory diagram of the cutting range of the knife portion when a rotary grass cutting blade is driven. It shows the cutting range of the inclined blade portion (rotational trajectory by the tip of the knife portion) with a dashed-dotted line, and the cutting range of the straight blade portion (rotational trajectory by the tip of the knife portion) with a dashed-dotted line. [Figure 11] (a) is one modified example (Modification 1) of the mounting base, knife part, and second mounting shaft of the rotary grass cutting blade, and (b) is another modified example (Modification 2) of the mounting base, knife part, and second mounting shaft of the rotary grass cutting blade. [Modes for carrying out the invention]

[0059] The embodiments of the present invention will be described in more detail with reference to Figures 1 to 11. The following description will be in the order of [First Embodiment], [Modification 1], and [Modification 2]. Reference numerals in each figure are used to reduce complexity and facilitate understanding, and in the case of multiple equivalent parts that share the same reference numeral, only some of them may be given a reference numeral. Reference numerals for arrows shown in Figure 1 and other figures indicate explanatory directions, with F meaning "forward," B meaning "rearward," R meaning "right" when viewed from the rear of the aircraft, L meaning "left" when viewed from the rear of the aircraft, U meaning "up," and D meaning "down."

[0060] [Grass trimmer 1] The lawnmower 1 will be described with reference to Figures 1 to 10. The self-propelled, walk-behind lawnmower 1 comprises a lawnmower body 2, a driving mechanism 3, a prime mover 4, a power transmission unit 5 on the cutting blade side, and a rotary cutting blade unit 6 (see Figures 1 and 2). Each part will be described in detail below.

[0061] (Grass trimmer main body 2) Refer to Figure 1(a). The main body 2 of the lawnmower has a frame 20, an operating handle 21, and a base frame 22. The frame 20 is made of a rigid material (metal in this embodiment) and is positioned from the center to the rear of the machine.

[0062] The operating handle 21 is a two-handed type with an operating shaft that is roughly V-shaped in plan view, with the tip that serves as the gripping part extending to the rear of the machine body, and the base end attached to the frame 20 and supported so as to be able to be raised and lowered in the vertical direction of the machine body. The operating handle 21 of this embodiment has a structure that includes at least a travel clutch lever for moving the machine body, a throttle lever for adjusting the rotational speed of the prime mover 4, and a grass cutting blade clutch lever for operating the drive of the rotary grass cutting blade 6 (reference numerals omitted), but is not limited thereto, and may have other functions such as an operating lever for raising and lowering the handle position.

[0063] The base frame 22 is a plate made of a rigid material (metal in this embodiment) and is located below the aircraft body. The base frame 22 has a first base frame 221 located on the right side of the aircraft body and a second base frame 222 located on the left side of the aircraft body.

[0064] The first base frame 221 and the second base frame 222 are connected via a hinge, and the second base frame 222 is rotatable within a set angle range (e.g., 1° to 30°) with respect to the first base frame 221 (horizontal, 0°).

[0065] The first base frame 221 has a load-bearing capacity sufficient to support the frame 20, the operating handle 21, the prime mover 4, and the grass cutting blade side power transmission unit 5 on its upper surface, and the driving means unit 3 can be attached to its front and rear parts, and the rotary grass cutting blade unit 6 can be attached to its lower surface (see Figures 1-2).

[0066] The first base frame 221 and the second base frame 222 are each provided with a cutting height adjustment lever (not shown) which allows for adjustment of their height or inclination angle. These levers work in cooperation with the rotary grass cutting blade 6, which is located on the underside of the first base frame 221 and the second base frame 222, to adjust the cutting height.

[0067] (Driving mechanism 3) The driving mechanism 3 has a first front wheel 31, a rear wheel 32, and a second front wheel 33 (see Figure 1).

[0068] The first front wheel 31 is positioned in front of the first base frame 221 and is both a steering wheel and a secondary drive wheel. The rear wheel 32 is positioned behind the first base frame 221 and is the primary drive wheel. The second front wheel 33 is positioned in front of the second base frame 222 and is a rolling wheel. In other words, the lawnmower 1 has a two-wheel drive (2WD) structure in which the first front wheel 31 and the rear wheel 32 are driven by power supplied from the prime mover 4.

[0069] (Motor 4) The prime mover 4 is mounted at the rear of the frame 20 and, in this embodiment, is an engine. The prime mover 4 supplies power to the rear wheels 32 via a first power transmission structure (not shown) and to the first front wheels 31 via a second power transmission structure (not shown).

[0070] Furthermore, the prime mover 4 supplies power to the first transmission shaft 51 (described later) on the grass cutting blade side power transmission unit 5 via a third power transmission structure (not shown), and also supplies power to the second transmission shaft 52 (described later) on the grass cutting blade side power transmission unit 5 via a fourth power transmission structure (not shown).

[0071] (Power transmission section 5 on the grass cutting blade side) The grass cutting blade-side power transmission unit 5 has a first transmission shaft 51 and a second transmission shaft 52. The first transmission shaft 51 and the second transmission shaft 52 are connected by a flexible fifth power transmission structure 53 (see Figure 1(a)). The first transmission shaft 51 is connected to the first grass cutting blade section 60A, and the second transmission shaft 52 is connected to the second grass cutting blade section 60B. The first transmission shaft 51 and the second transmission shaft 52 are provided with male screw portions 511 and 521 at their respective shaft ends (see Figure 3).

[0072] (Rotating grass cutting blade section 6) The rotary grass cutting blade unit 6 has a first grass cutting blade unit 60A and a second grass cutting blade unit 60B (see Figures 1(b) and 2). The parts of the rotary grass cutting blade unit will be described in detail below. Since the first grass cutting blade unit 60A and the second grass cutting blade unit 60B have the same structure, only the first grass cutting blade unit 60A will be described in detail, and the illustration and description of the second grass cutting blade unit 60B in Figure 3 and beyond will be omitted.

[0073] <First grass cutting blade section> The first grass cutting blade section 60A includes an output shaft cover section 602, a fixing plate 605, a mounting base section 61, a knife section 62, a connector 65, a fixing device 66, a first mounting shaft 67, and a second mounting shaft 68. Each part of the first grass cutting blade section 60A will be described in detail below.

[0074] <Output shaft cover section> The output shaft cover portion 602 is a bottomed cylindrical shape that tapers in diameter from top to bottom, and is positioned between the first base frame 221 and the mounting base 61. The output shaft cover portion 602 has a first through hole 603 formed in the center of its bottom surface through which the first transmission shaft 51 (output shaft) is inserted, and encloses the first transmission shaft 51 (output shaft) in a manner that it is inserted in the height direction.

[0075] Furthermore, the output shaft cover portion 602 has multiple (four in this embodiment) second through holes 604 formed around the first through hole 603 through which bolts connecting it to the mounting base portion 61 are inserted, and is provided so as to be rotatable in the circumferential direction when connected to the mounting base portion 61 via bolts (see Figures 3 and 8).

[0076] <Fixing plate> The fixing plate 605 is provided with a third through hole 606 and a fourth through hole 607.

[0077] The third through-hole 606 is formed in the center of the plate substrate and is provided in a cylindrical shape, acting as a spacer to maintain a predetermined distance between the tip of the first transmission shaft 51 (output shaft) and the plate substrate. Furthermore, the third through-hole 606 has a spline receiving groove (not shown) formed on its inner circumferential surface, and is structured to engage with a spline portion (not indicated) provided on the first transmission shaft 51 (second transmission shaft 52) ​​closer to the shaft base than the male thread portion 511 (521) (see Figures 3 and 8).

[0078] The fourth through-hole 607 is formed in a pair (a total of two locations) in the longitudinal direction of the plate substrate, flanking the third through-hole 606, and is arranged to communicate with the aforementioned second through-hole 604. Furthermore, the nut portion of the fourth through-hole 607 is fixed to the same surface as the cylindrical projection of the third through-hole 606.

[0079] <Mounting base> The mounting base 61 is a roughly oval plate shape and is provided with a fifth through hole 611, a sixth through hole 612, and a first mounting hole 613 for attaching the knife portion 62.

[0080] The fifth through-hole 611 is formed at the intersection of the long axis and short axis of the mounting base 61 and is provided so that the tip of the first transmission shaft 51 (output shaft) can be inserted through it. The sixth through-hole 612 is formed in pairs (a total of 4 locations) on either side of the fifth through-hole 611, in the direction of the long axis and the direction of the short axis of the mounting base 92, and is arranged so as to be able to communicate with the second through-hole 604 and the fourth through-hole 607 described above.

[0081] The first mounting holes 613 are formed in pairs (two in total) near the peripheral edge portion in the longitudinal direction of the mounting base 61, flanking the fifth through hole 611, and are arranged to communicate with the second mounting holes 634 (644) of the first knife 63 and the second knife 64, which will be described later. The first mounting holes 613 have spline receiving grooves formed on their inner surface, and the cylindrical gaps formed on the top surfaces of each furrow portion between the spline receiving grooves have an inner diameter that allows the cylindrical portion 674 of the first mounting shaft 67, which will be described later, to rotatably receive, and are set to be slightly larger in diameter than the cylindrical portion 674.

[0082] In other words, the mounting base 61, after being connected to the output shaft (first transmission shaft 51 / second transmission shaft 52), the output shaft cover portion 602, and the fixing plate 605, has a structure in which "the central portion is connected to the prime mover and is rotatably mounted by receiving power from the prime mover, and a first mounting hole for attaching the knife portion is formed near the peripheral portion."

[0083] <Knife section> The knife section 62 is a pair having a first knife 63 and a second knife 64 provided at a predetermined length. The first knife 63 and the second knife 64 each have a similar structure and, in their longitudinal direction, have a base region 631 (641), an intermediate region 632 (642), and a tip region 633 (643).

[0084] The base region 631 (641) is the mounting portion to the mounting base 61, and is horizontal (parallel to the mounting base 61) when mounted to the mounting base 61. The intermediate region 632 (642) is the portion that slopes away from the base region 631 (641) when mounted to the mounting base 61. The tip region 633 (643) is the portion that slopes more gently than the intermediate region 632 (642) when mounted to the mounting base 61, and whose tip slopes away from the base region 631 (641).

[0085] The first knife 63 and the second knife 64 have a second mounting hole 634 (644) formed in the base region 631 (641). The second mounting hole 634 (644) has a spline receiving groove formed on its inner surface, and the cylindrical gap formed on the top surface of each furrow portion between the spline receiving grooves has an inner diameter that allows the cylindrical portion 674 of the first mounting shaft 67 (described later) to rotatably receive, and is set to be slightly larger in diameter than the cylindrical portion 674. In addition, the first knife 63 and the second knife 64 are provided with single-edged blade portions 635 (645) on both sides of the tip region 633 (643).

[0086] In other words, the knife portion 62 has a predetermined length, with a blade portion provided on the tip side and / or the side, and a second mounting hole formed on the base side that corresponds to the shape of the first mounting hole. The knife portion is a pair consisting of a first knife and a second knife, with the first knife arranged on one side of the mounting base and the second knife arranged on the other side of the mounting base.

[0087] <Connectors> The connector 65 is a component that connects the output shaft cover portion 602, the fixing plate 605, and the mounting base portion 61. In this embodiment, the connector 65 is composed of a bolt (reference numeral omitted) and a washer (reference numeral omitted), but it can be replaced with a known component that provides equivalent functionality.

[0088] <Fixing fixture> The fixing device 66 is attached to the tip of the male threaded portion 511 of the first transmission shaft 51 in the grass cutting blade side power transmission unit 5, and is a component that connects the output shaft cover portion 602, the fixing plate 605, and the mounting base portion 61. In this embodiment, the fixing device 66 is composed of a cap nut (reference numeral omitted), a washer (reference numeral omitted), and a spring washer (reference numeral omitted), but it can be replaced with a known component that provides equivalent effects.

[0089] <First mounting shaft> The first mounting shaft 67 has a shaft head 671 and a shaft portion 672 which is smaller in diameter than the shaft head 671. The first mounting shaft 67 has a male screw 673 formed in the region of the shaft portion 672 in the direction of the shaft tip, and a cylindrical portion 674 formed in the intermediate part between the shaft head 671 and the region where the male screw 673 is formed. In other words, the first mounting shaft has a structure in which it "has a cylindrical portion" and "has a male screw formed in the region in the direction of the shaft tip, and a cylindrical portion formed in the intermediate part excluding the region where the male screw is formed."

[0090] <Second mounting shaft> The second mounting shaft 68 has a shaft head 681 and a shaft portion 682 which is smaller in diameter than the shaft head 681. The second mounting shaft 68 has a male screw 683 formed in the region of the shaft portion 682 in the direction of the shaft tip, and a spline portion 684 is formed in the intermediate portion between the shaft head 681 and the region where the male screw 683 is formed, which can engage with a spline receiving groove provided in the first mounting hole 613 of the mounting base 61. In other words, the second mounting shaft has a structure in which "a convex portion is provided in the direction of the long axis of the shaft surface" and "a male screw is formed in the region in the direction of the shaft tip, and a spline portion is formed in the intermediate portion excluding the region where the male screw is formed."

[0091] <Mounting shaft fixing device> The mounting shaft fixing device 69 is attached to either the tip of the male thread 673 of the first mounting shaft 67 or the tip of the male thread 683 of the second mounting shaft 68, and is a component that connects the first knife 63, the mounting base 61, and the second knife 64. In this embodiment, the mounting shaft fixing device 69 is composed of a cap nut (reference numeral omitted) and a washer (reference numeral omitted), but it can be replaced with a known component that provides equivalent functionality.

[0092] In other words, the rotary grass cutting blade 6 is configured such that "the first knife, which is the knife part, is arranged on one side of the mounting base, and the second knife is arranged on the other side of the mounting base, sandwiching it between them," and "it is mounted by inserting either the first mounting shaft or the second mounting shaft, which is selectively applied depending on the application, with the first mounting hole of the mounting base, the second mounting hole of the first knife, and the second mounting hole of the second knife overlapping."

[0093] In this embodiment, the prime mover is an engine, but is not limited to that, and may be an electric motor, for example. Furthermore, the prime mover is structured to supply power to the first front wheel and the rear wheel using a power transmission structure with two paths, but is not limited to that, and may be structured to supply power to the first front wheel and the rear wheel using a power transmission structure with one or three or more paths. Moreover, the prime mover is structured to supply power to the first transmission shaft and the second transmission shaft using a power transmission structure with two paths, but is not limited to that, and may be structured to supply power to the first transmission shaft and the second transmission shaft using a power transmission structure with one or three or more paths.

[0094] In this embodiment, the driving means unit 3 has a 2WD structure in which the first front wheel 31 and rear wheel 32 are driven, and has a second front wheel 33. However, it is not limited to this, and may have a structure with independent driving wheels such as two, four, or six wheels, or part or all of the driving means unit may have a tracked driving structure.

[0095] In this embodiment, the rotary grass cutting blade 6 has the configuration described above, but it is not limited to this and can be modified as appropriate. For example, various combinations of gears, chains, or belts can be used as the power transmission structure. In addition, the shape of the base, the number and position of the knives constituting the knife section, or the arrangement of the knife section can be changed, and a structure in which the knives are not in pairs in the vertical direction can also be adopted. Furthermore, the output shaft cover section may have other shapes besides the shape described above, such as a simple cylindrical shape that is not reduced in diameter, or a structure without an output shaft cover section can be adopted. In addition, in this embodiment, the rotary grass cutting blade 6 is configured to be detachable from the grass cutter 1 as described above, but it is not limited to this, and a configuration in which it cannot be detached from the grass cutter can also be adopted.

[0096] (effect) The operation and effects of the grass trimmer 1 will be explained with reference to Figures 1 to 9. The grass trimmer 1 can perform weeding work using a rotary grass cutting blade 6 driven by a prime mover 4 while it is in motion. Before starting work, the grass trimmer 1 selectively applies either a first mounting shaft 67 or a second mounting shaft 68 to the rotary grass cutting blade 6, depending on the application.

[0097] The rotary grass cutting blade unit 6 can be used to perform a grass cutting method in a free-knife configuration (in other words, the "first grass cutting method") by attaching the knife part 62 to the mounting base 61 by applying the first mounting shaft 67. The rotary grass cutting blade unit 6 can be used to perform a grass cutting method in a straight blade configuration or an inclined blade configuration (in other words, the "second grass cutting method") by attaching the knife part 62 to the mounting base 61 by applying the second mounting shaft 68.

[0098] <Application of the first mounting shaft: First grass cutting method> In a grass trimmer 1 to which a first mounting shaft 67 is applied to a rotary grass trimming blade 6, the pair of knife parts 62 (first knife 63 and second knife 64) of the first grass trimming blade 60A (and second grass trimming blade 60B) are attached to the mounting base 61 in a free-knife configuration, where they are rotatable around the first mounting shaft 67, which is fitted into the first mounting hole 613 and the second mounting holes 634 and 644. The aforementioned rotatable state is achieved when the cylindrical portion 674 of the first mounting shaft 67 is held by the surface of the protruding tip of the spline receiving groove provided in the first mounting hole 613 and the second mounting holes 634 and 644.

[0099] Each knife portion 62, which is in a free-knife configuration, extends circumferentially in a straight blade shape due to centrifugal force as the first grass-cutting blade portion 60A (and the second grass-cutting blade portion 60B) rotates, and cuts (weeds) the vegetation that it collides with using the blade portion 635 of the first knife 63 and the blade portion 645 of the second knife 64 (see Figure 8(a)).

[0100] On the other hand, when the blade portions 635 and 645 come into contact with a hard object (something that is a target for weeding but cannot be cut, or something other than a target for weeding; obstacle X shown in Figure 8), the knife portion 62 moves in the rotational direction to reduce or deflect the impact (see the direction of the arrow in Figure 8(b)). This suppresses damage to the knife portion 62 including the blade portions 635 and 645, the mounting base 61, and the weed trimmer drive system, and further suppresses damage to the obstacle X (object that the knife portion 62 collides with).

[0101] Furthermore, after the knife section 62 moves in the rotational direction due to collision with obstacle X, the knife section 62 extends circumferentially in a straight blade shape due to centrifugal force (returning to its original position), so weeding work can continue without stopping the machine.

[0102] Furthermore, in the grass trimmer 1 in which the first mounting shaft 67 is applied to the rotary grass trimming blade section 6, there is less scattering of debris and less wear on the blade portion per unit area compared to a grass trimming blade with a bar knife structure. Moreover, because the cylindrical gaps in the first mounting holes 613 and the second mounting holes 634-644 are slightly larger in diameter than the cylindrical portion 674, the cylindrical portion 674, when fitted into the first mounting holes 613 and the second mounting holes 634-644, can rotate smoothly within the cylindrical gap with less rattle.

[0103] <Application of the second mounting shaft: Second grass cutting method> In a grass trimmer 1 to which a second mounting shaft 68 is applied to a rotary grass trimming blade 6, the pair of knife sections 62 (first knife 63 and second knife 64) of the first grass trimming blade 60A (and second grass trimming blade 60B) are attached to the mounting base 61 in a straight blade configuration or an inclined blade configuration, fixed so as not to rotate around the second mounting shaft 68 which is fitted into the first mounting hole 613 and the second mounting holes 634 and 644. Furthermore, the aforementioned non-rotatable fixed state is achieved by the engagement of the spline portion 684 of the second mounting shaft 68 with the spline receiving grooves provided in the first mounting hole 613 and the second mounting holes 634 and 644.

[0104] In other words, in the second grass cutting method, when attaching the second mounting shaft 68 to each knife section 62 and mounting it to the mounting base 61, it is possible to select either a straight blade configuration (parallel configuration) as shown in Figure 9(a) or an inclined blade configuration including a V-shape as shown in Figure 9(b). Thus, in the second grass cutting method using the rotary grass cutting blade section 6, a single rotary grass cutting blade can accommodate three different applications or methods of use.

[0105] Furthermore, the rotary grass cutting blade unit 6, while being a single rotary grass cutting blade unit, can accommodate four types of actions: the free knife action of the first grass cutting method described above, and the three types of actions of the second grass cutting method. The rotary grass cutting blade unit 6 is composed of a pair of knife units 62 consisting of a first knife 63 and a second knife 64, but it is also possible to use either the first knife 63 or the second knife 64 alone by attaching them to the mounting base 61 in a straight blade or inclined blade configuration.

[0106] Each knife section 62, which is either a straight blade or an inclined blade, rotates in conjunction with the rotation of the first cutting blade section 60A (and the second cutting blade section 60B), similar to a bar knife structure, and cuts (weeds) the vegetation it collides with using the blade portion 635 of the first knife 63 and the blade portion 645 of the second knife 64. Each knife section 62, which is either a straight blade or an inclined blade, can cut with great force and does not move backward when it hits the target to be cut, resulting in a clean cut.

[0107] In other words, with the rotary grass cutting blade 6, when the mounting base 61 is parallel to the ground, each knife section 62 has a straight blade configuration with a first knife 63 and a second knife 64 arranged vertically apart, enabling efficient and even weeding work. Furthermore, with the rotary grass cutting blade 6, weeding work can also be performed by selectively attaching either the first knife 63 or the second knife 64 to the top or bottom of the mounting base 61 in each knife section 62.

[0108] Furthermore, with the rotary grass cutting blade 6, in the straight blade configuration or the inclined blade configuration to which the second mounting shaft 68 is applied, it is also possible to choose to have the first knife 63 and the second knife 64 in either a parallel configuration or a V-shaped configuration.

[0109] In the first grass-cutting blade section 60A (and the second grass-cutting blade section 60B) in which the first knife 63 and the second knife 64 form a V-shape, the first knife 63 and the second knife 64 strike the target to be cut, such as grass and trees, twice at different timings in one knife section 62, and the cutting is performed by the first knife 63 and the second knife 64 which are positioned apart in the vertical direction. As a result, even though it is a single knife section, the work efficiency is further improved and weeding work can be performed with evenly spaced cuts.

[0110] In addition, since the first cutting blade section 60A (and the second cutting blade section 60B) has two sets of knife sections 62, all the knives (63 and 64) make contact with the target to be cut, such as grass, a total of four times per rotation at different timings. This allows it to handle thicker or harder stems or sticky grass, and it can cut with the same force as a bar-knife cutting blade. Furthermore, since the knife section does not move away (reverse) when it hits the target to be cut, it results in a clean cut.

[0111] Furthermore, in the rotary grass cutting blade section 6, spline receiving grooves are formed in the first mounting hole 613 and the second mounting holes 634 and 644, and a spline portion 684 is formed on the second mounting shaft 68. This allows for fine angle adjustment of the angle formed by the bases of the first knife 63 and the second knife 64 (the degree of opening of each knife tip) when forming an inclined blade configuration or a V-shaped configuration.

[0112] The functions and effects of the other parts of the lawnmower 1 are as follows:

[0113] The frame 20 of the main body 2 of the brush cutter serves as the mounting base for the operating handle 21 and the base frame 22. During operation, the operator uses the operating handle 21 to move the machine by operating its travel clutch lever, adjusts the rotational speed of the prime mover 4 by operating its throttle lever, and operates the drive of the rotary brush cutter blade 6 by operating its brush cutter blade clutch lever.

[0114] The first base frame 221 and the second base frame 222, which constitute the base frame 22, each serve as a mounting base for the rotary grass cutting blade section 6 (first grass cutting blade section 60A and second grass cutting blade section 60B).

[0115] The first base frame 221 and the second base frame 222 are rotatably connected via a hinge, allowing the second base frame 222 to be tilted along the slope at a required angle when working near an embankment to perform weeding. This enables simultaneous mowing of grass on both the flat and sloping areas near the embankment, while the worker can walk on the flat area, reducing physical strain and ensuring safe work. On the other hand, on flat ground, weeding can be performed over a wide area by positioning both the first base frame 221 and the second base frame 222 horizontally.

[0116] Furthermore, the effects of the other parts of the rotary grass cutting blade unit 6 are as follows. The rotary grass cutting blade unit 6 is provided with a mounting base 61 that is rotatable by receiving power in the central part, so that it rotates itself, and as it rotates, each knife part 62 attached near the peripheral part of the mounting base 61 also rotates, and weeding work can be performed by the blade parts 635 and 645 of each rotating knife part 62. And, due to the structure described above, each knife part 62 can be inserted into the first mounting hole to attach either the first mounting shaft 67 or the second mounting shaft 68, which can be selected and applied according to the application.

[0117] Furthermore, the rotary grass cutting blade unit 6 has an output shaft cover unit 602, which prevents the cutting material before and after cutting from directly wrapping around and becoming entangled in the output shaft, either the first transmission shaft 51 or the second transmission shaft 52, during rotation. In addition, the rotary grass cutting blade unit 6 has a fixing plate 605, which firmly engages the receiving groove formed in the third through hole 606 of the plate with the spline portion formed on the first transmission shaft 51 (second transmission shaft 52), ensuring reliable and efficient power transmission.

[0118] Thus, with the grass trimmer 1 equipped with a rotary grass cutting blade section 6, despite its simple configuration and the use of only one type of rotary grass cutting blade, it can accommodate four types of uses or methods of operation: a free-knife configuration with the two blades of the first knife 63 and the second knife 64, a straight blade configuration (parallel configuration), an inclined blade configuration (parallel configuration), and a V-shaped configuration. Furthermore, if we include the free-knife configuration, straight blade configuration, and inclined blade configuration, which can be performed by selectively attaching either the first knife 63 or the second knife 64 above or below the mounting base 61, a total of seven types of weeding operations can be performed.

[0119] Furthermore, the cutting range of the rotary grass cutting blade 6 can be adjusted by changing (selecting) between a straight blade configuration and an inclined blade configuration. Specifically, when the straight blade configuration is selected, the cutting range of the rotary grass cutting blade 6 can be set to its maximum (in Figure 10, the cutting range of the knife portion 62 in the straight blade configuration is shown by a dashed line (see the rotational trajectory R1 drawn by the tip of the knife portion 62)).

[0120] On the other hand, when the inclined blade configuration is selected, the cutting range of the rotary grass cutting blade 6 can be set to be narrower (smaller) than the cutting range of the straight blade configuration (see the cutting range of the knife part 62 of the inclined blade configuration shown by the solid line in Figure 10 (refer to the rotational trajectory R2 drawn by the tip of the knife part 62)), and the larger the inclination angle (flatter) of the knife part 62, the narrower (smaller) the cutting range can be made. This makes it easier to perform detailed weeding in areas with many obstacles near the target area by adjusting the cutting range to be narrower, and this adjustment can be easily made on-site, making it convenient and increasing the safety of the machine and the operator when using the grass cutter 1.

[0121] [Variation 1] Referring to Figure 11(a), a modified example (Modification Example 1) of the mounting base 61, knife section 62, and second mounting shaft 68 of the rotary grass cutting blade section 6 will be described. Note that for the mounting base 61a, knife section 62a, and second mounting shaft 68a of Modification Example 1, the explanation of their structure and effects will be omitted as they are common to the mounting base 61, knife section 62, and second mounting shaft 68.

[0122] The mounting base 61a is provided with a pair of first mounting holes 613a for attaching the knife portion 62a, and the first mounting holes 613a are arranged to communicate with the second mounting holes 634a (644a) of the first knife 63a and the second knife 64a, which will be described later. The first mounting holes 613a are formed as octagonal holes, with the shape of the inner surface of the hole being octagonal in plan view, and the gap formed by the surfaces between the corners has an inner diameter that allows the cylindrical portion 674 of the first mounting shaft 67 to rotatably receive, and is set to be slightly larger in diameter than the cylindrical portion 674.

[0123] The knife section 62a is a pair having a first knife 63a and a second knife 64a provided at a predetermined length. The first knife 63a and the second knife 64a each have a similar structure and, in their longitudinal direction, have a base region 631a (641a), an intermediate region 632 (642), and a tip region 633 (643), which are mounting portions to the mounting base 61a where the second mounting hole 634a (644a) is formed. The second mounting hole 634a (644a) is formed as an octagonal hole with an octagonal shape in plan view of its inner surface, and the gap formed by the surfaces between the corners has an inner diameter that allows the cylindrical portion 674 of the first mounting shaft 67 to rotatably receive it, and is set to be slightly larger in diameter than the cylindrical portion 674.

[0124] The second mounting shaft 68a has a shaft head 681 and a shaft portion 682a that is smaller in diameter than the shaft head 681. The second mounting shaft 68a has a male screw 683 formed in the axial direction region of the shaft portion 682a, and a rectangular prism portion 685a is formed in the intermediate portion between the shaft head 681 and the male screw 683 formation region, which can engage with the first mounting hole 613a of the mounting base 61a and the octagonal holes provided in the second mounting holes 634a (644a) of the first knife 63a and the second knife 64a.

[0125] (effect) The effects of the mounting base 61a, the knife portion 62a, and the second mounting shaft 68a will be explained.

[0126] When the first mounting shaft 67 is applied to the combination of the mounting base 61a and the knife portion 62a, the pair of knife portions 62a (first knife 63a and second knife 64a) are attached to the mounting base 61a in a free-knife configuration that can rotate around the first mounting shaft 67, which is fitted into the first mounting hole 613a and the second mounting holes 634a and 644a, and the first grass cutting method can be carried out.

[0127] When the second mounting shaft 68a is applied to the combination of the mounting base 61a and the knife portion 62a, the pair of knife portions 62a (first knife 63a and second knife 64a) are attached to the mounting base 61a in a straight blade configuration or an inclined blade configuration, fixed so as not to rotate by the second mounting shaft 68a which is fitted into the first mounting hole 613a and the second mounting holes 634a and 644a, and the second grass cutting method can be carried out. This non-rotatable fixed state is achieved by the engagement of the rectangular prism portion 685a of the second mounting shaft 68a with the first mounting hole 613a and the second mounting holes 634a and 644a provided in the octagonal hole.

[0128] In other words, in the second grass cutting method in Modification 1, when attaching the second mounting shaft 68a to each knife portion 62a to the mounting base 61a, it is possible to select either a straight blade configuration (parallel configuration) as shown in Figure 9(a) or an inclined blade configuration including a V-shape configuration as shown in Figure 9(b). Furthermore, by adding the free knife configuration of the first grass cutting method described above, it is possible to accommodate a total of four configurations, combining the three configurations of the second grass cutting method.

[0129] Furthermore, according to the second grass cutting method in Modification 1, the first mounting hole 613a and the second mounting holes 634a and 644a are provided as octagonal holes, and an octagonal prism portion 685a is formed on the second mounting shaft 68a. This allows for fine angle adjustment of the angle formed by the bases of the first knife 63a and the second knife 64a (the degree of opening of each knife tip) when forming an inclined blade configuration or a V-shaped configuration.

[0130] [Variation 2] Referring to Figure 11(b), a modified example (modified example 2) of the mounting base 61, knife section 62, and second mounting shaft 68 of the rotary grass cutting blade section 6 will be described. Note that for the mounting base 61b, knife section 62b, and second mounting shaft 68b of modified example 2, the explanation of their structure and effects will be omitted as they are common to the mounting base 61, knife section 62, and second mounting shaft 68.

[0131] The mounting base 61b is provided with a pair of first mounting holes 613b for attaching the knife portion 62b, and the first mounting holes 613b are arranged to communicate with the second mounting holes 634b (644b) of the first knife 63b and the second knife 64b, which will be described later. The first mounting holes 613b are formed as star-shaped holes, with the shape of the inner surface of the hole in plan view being a hexagram, and the virtual cylindrical gap formed by connecting the corners formed on the inner surface of the hole has an inner diameter that can rotatably accommodate the cylindrical portion 674 of the first mounting shaft 67, which will be described later, and the aforementioned virtual cylindrical gap formed at the inner corners of the hole is set to be slightly larger in diameter than the cylindrical portion 674.

[0132] The knife section 62b is a pair having a first knife 63b and a second knife 64b provided at a predetermined length. The first knife 63b and the second knife 64b each have a similar structure and, in their longitudinal direction, have a base region 631b (641b), an intermediate region 632 (642), and a tip region 633 (643), which are mounting portions to the mounting base 61b where the second mounting hole 634b (644b) is formed. The second mounting hole 634b (644b) is formed as a star-shaped hole with a hexagram shape in plan view of its inner surface, and the virtual cylindrical gap formed by connecting the corners formed on the inner surface of the hole has an inner diameter that can rotatably receive the cylindrical portion 674 of the first mounting shaft 67, which will be described later. The aforementioned virtual cylindrical gap formed at the inner corner of the hole is set to be slightly larger in diameter than the cylindrical portion 674.

[0133] The second mounting shaft 68b has a shaft head 681 and a shaft portion 682b that is smaller in diameter than the shaft head 681. The second mounting shaft 68b has a male screw 683 formed in the axial direction region of the shaft portion 682b, and a prismatic portion 685b is formed in the intermediate portion between the shaft head 681 and the male screw 683 formation region, which can engage with the first mounting hole 613b of the mounting base 61b and the star-shaped holes provided in the second mounting holes 634b (644b) of the first knife 63b and the second knife 64b.

[0134] (effect) The effects of the mounting base 61b, the knife portion 62b, and the second mounting shaft 68b will be explained.

[0135] When the first mounting shaft 67 is applied to the combination of the mounting base 61b and the knife portion 62b, the pair of knife portions 62b (first knife 63b and second knife 64b) are attached to the mounting base 61b in a free-knife configuration that can rotate around the first mounting shaft 67, which is fitted into the first mounting hole 613b and the second mounting holes 634b and 644b, and the first grass cutting method can be carried out.

[0136] When the second mounting shaft 68b is applied to the combination of the mounting base 61b and the knife portion 62b, the pair of knife portions 62b (first knife 63b and second knife 64b) are attached to the mounting base 61b in a straight blade configuration or an inclined blade configuration, fixed so as not to rotate by the second mounting shaft 68b which is fitted into the first mounting hole 613b and the second mounting holes 634b and 644b, and the second grass cutting method can be carried out. This non-rotatable fixed state is achieved by the engagement of the rectangular prism portion 685b of the second mounting shaft 68b with the first mounting hole 613b and the second mounting holes 634b and 644b provided in the star-shaped hole.

[0137] In other words, in the second grass cutting method in the modified example 2, when attaching the second mounting shaft 68b to each knife section 62b and mounting it to the mounting base 61b, it is possible to select either a straight blade configuration (parallel configuration) as shown in Figure 9(a) or an inclined blade configuration including a V-shape configuration as shown in Figure 9(b). Furthermore, by adding the free knife configuration of the first grass cutting method described above, it is possible to accommodate a total of four configurations, combining the three configurations of the second grass cutting method.

[0138] Furthermore, according to the second grass cutting method in Modification 2, the first mounting hole 613b and the second mounting holes 634b and 644b are provided in a star shape, and a star-shaped prism portion 685b is formed on the second mounting shaft 68b. This allows for fine angle adjustment of the angle formed by the bases of the first knife 63b and the second knife 64b (the degree of opening of each knife tip) when forming an inclined blade configuration or a V-shape configuration.

[0139] The terms and expressions used in this specification and claims are for illustrative purposes only and are not limiting in any way, and there is no intention to exclude terms or expressions equivalent to or including the features described herein and in the claims. Furthermore, it goes without saying that various modifications are possible within the scope of the technical concept of the present invention. Also, terms such as "first," "second," etc., do not imply rank or importance, but are used to distinguish one element from others. [Explanation of Symbols]

[0140] 1. Lawn mower 2. Main body of the brush cutter, 20. Frame, 21. Operating handle, 22. Base frame, 221. First base frame, 222. Second base frame 3. Running mechanism, 31. First front wheel, 32. Rear wheel, 33. Second front wheel 4. Engine 5. Power transmission section on the grass cutting blade side, 51. First transmission shaft, 511. Male threaded portion, 52. Second transmission shaft, 521. Male threaded portion 521, 53. Fifth power transmission structure 6. Rotary grass cutting blade section 60A First grass cutting blade section 60B Second Grass Cutting Blade 602 Output shaft cover section, 603 First through hole, 604 Second through hole 605 Fixing plate, 606 Third through hole, 607 Fourth through hole, 61, 61a, 61b Mounting base, 611 Fifth through hole, 612 Sixth through hole, 613, 613a, 613b First mounting hole 62, 62a, 62b Knife section 63, 63a, 63b First knife; 631, 631a, 631b Base region; 632 Intermediate region; 633 Tip region; 634, 634a, 634b Second mounting hole; 635 Blade portion 64, 64a, 64b Second knife; 641, 641a, 641b Base region; 642 Intermediate region; 643 Tip region; 644, 644a, 644b Second mounting hole; 645 Blade portion 65 Connectors 66 Fixtures 67 First mounting shaft, 671 Shaft head, 672 Shaft section, 673 Male thread, 674 Cylindrical section 68, 68a, 68b Second mounting shaft body, 681 Shaft head, 682, 682a, 682b Shaft section, 683 Male thread, 684 Spline section, 685a, 685b Rectangular prism section 69 Mounting shaft fixing device X Obstacle R1, R2 rotation trajectory

Claims

1. It comprises a mounting base and a knife part, The mounting base is rotatably mounted in its central portion by receiving power, and a first mounting hole for attaching the knife portion is formed near the peripheral portion. The knife portion has a predetermined length, a blade portion is provided on the tip side and / or the side, and a second mounting hole is formed on the base side that corresponds to the shape of the first mounting hole. The mounting base and the knife portion are constructed to be mounted by inserting either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft having a polygonal prism shape with multiple corners around its circumference or a protrusion provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the first mounting hole and the second mounting hole overlapping. The first mounting hole and the second mounting hole are shaped to be open to a size that allows rotation around the axis when the first mounting shaft is inserted, and to have recesses formed on the inner surface of the holes that engage with the corner or protrusion when the second mounting shaft is inserted, thereby locking it so that it cannot rotate around the axis. Rotary grass cutting blade.

2. A first mounting shaft having a cylindrical portion around its circumference, The system further comprises a second mounting shaft which is a polygonal prism shape having multiple corners on its circumference or a convex portion provided in the direction of the long axis of the circumferential surface. The rotary grass cutting blade according to claim 1.

3. The first mounting shaft has a male thread formed in the region in the direction of the shaft tip, and a cylindrical portion formed in the intermediate portion excluding the male thread forming region. The second mounting shaft has a male thread formed in the region in the direction of the shaft tip, and a spline portion formed in the intermediate portion excluding the male thread forming region. The first and second mounting holes have spline receiving grooves formed on their inner surfaces, into which the spline portion can engage, and the cylindrical gaps formed on the top surfaces of each ridge portion between the spline receiving grooves are set to a size that allows the cylindrical portion of the first mounting shaft to rotatably receive it. The rotary grass cutting blade according to claim 2.

4. The knife portion is a pair having a first knife and a second knife, the first knife being disposed on the front side of the mounting base and the second knife being disposed on the back side, sandwiching the mounting base. The structure is such that the first mounting hole of the mounting base, the second mounting hole of the first knife, and the second mounting hole of the second knife overlap, and either the first mounting shaft or the second mounting shaft, which is selectively applied depending on the application, is inserted and mounted. A rotary grass cutting blade according to any one of claims 1 to 3.

5. It is used in rotary grass cutting blades. The main body is mounted in the center so as to be rotatable by receiving power. Near the peripheral edge of the main body, a first mounting hole is formed having a shape corresponding to the second mounting hole, in order to attach a grass-cutting knife portion having a predetermined length, with a blade portion provided on the tip side and / or side, and a second mounting hole formed on the base side. The knife portion to be attached is structured to be attached to the main body by inserting either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft that is polygonal in shape with multiple corners around its circumference or has protrusions provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the first mounting hole and the second mounting hole overlapping. The first mounting hole is sized to allow rotation around the axis when the first mounting shaft is inserted, and has a recess formed on its inner surface that engages with the corner or protrusion to lock the second mounting shaft so that it cannot rotate around the axis when the second mounting shaft is inserted. Mounting base.

6. It is used by attaching it to the mounting base of a rotary grass cutting blade. Having a predetermined length, with a blade portion provided on the tip side and / or the side, and a second mounting hole formed on the base side having a shape corresponding to the first mounting hole formed near the peripheral edge of the mounting base, The knife portion is mounted by inserting either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft having a polygonal prism shape with multiple corners around its circumference or a protrusion provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the second mounting hole and the first mounting hole of the mounting base overlapping. The second mounting hole is sized to allow rotation around the axis when the first mounting shaft is inserted, and has a recess formed on its inner surface that engages with the corner or protrusion to lock the second mounting shaft so that it cannot rotate around the axis when the second mounting shaft is inserted. Knife section.

7. It comprises a main body of a grass trimmer having a prime mover, and a rotary grass trimming blade having a mounting base and a knife part provided on the main body of the grass trimmer, The mounting base is connected to the prime mover in its central portion and is rotatable by power from the prime mover, and a first mounting hole for attaching the knife portion is formed near the peripheral portion. The knife portion has a predetermined length, a blade portion is provided on the tip side and / or the side, and a second mounting hole is formed on the base side that corresponds to the shape of the first mounting hole. The mounting base and the knife portion are constructed to be mounted by inserting either a first mounting shaft having a cylindrical portion around its circumference, or a second mounting shaft having a polygonal prism shape with multiple corners around its circumference or a protrusion provided in the direction of the long axis of the circumferential surface, which can be selectively applied depending on the application, with the first mounting hole and the second mounting hole overlapping. The first mounting hole and the second mounting hole are shaped to be open to a size that allows rotation around the axis when the first mounting shaft is inserted, and to have recesses formed on the inner surface of the holes that engage with the corner or protrusion when the second mounting shaft is inserted, thereby locking it so that it cannot rotate around the axis. Lawn mower.

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