Cutting blades for grass cutter

Abstract

To reduce situations in which pebbles or the like on the ground are hit by a base part of cutting blades and jump outside a housing of the grass cutter in the cutting blades for a grass cutter.SOLUTION: Cutting blades for a grass cutter include: a base part 60 which has a first extension part 60a extended in one direction from a lower part of a driving shaft and a second extension part 60b extended in the other direction opposite from the lower part of the driving shaft; a first cutting blade part 61 which is provided for the first extension part 60a so that it extends outward from the first extension part 60a; and a second cutting blade part 62 which is provided for the second extension part 60b so that it extends outward from the second extension part 60b. An edge part on an upstream side in a rotary direction of the base part 60 in the first extension part 60a and a second extension part 60b is formed on inclined surfaces 60c, 60d which face diagonally upward or diagonally downward in the rotation direction.SELECTED DRAWING: Figure 11

Description

[Technical Field]

[0001] The present invention provides Walk-behind grass cutter Regarding. [Background technology]

[0002] Patent Document 1 discloses a blade that is equipped on a walk-behind mower. In the blade of Patent Document 1, the base of the blade is attached to the bottom of a drive shaft that extends in the vertical direction of the mower housing, and the blade section is attached to both ends of the base so that it can swing freely around an axis that also extends in the vertical direction.

[0003] Patent Document 2 discloses a blade that is equipped on a riding mower. In the blade of Patent Document 2, the base of the blade is attached to the bottom of a drive shaft that is aligned in the up-down direction of the housing of the mower, the base extends from the bottom of the drive shaft, and the blade part is formed on the extension of the base. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-273584 [Patent Document 2] Japanese Patent Application Laid-Open No. 2015-29481 Summary of the Invention [Problem to be solved by the invention]

[0005] In the blades disclosed in Patent Documents 1 and 2, the base of the blade is rotationally driven by a drive shaft, and grass is cut by the cutting blade portion of the blade. In this case, the base of the blade does not have a blade portion for cutting grass, so when the base of the blade hits pebbles or the like on the ground, the pebbles or the like may be kicked off and fly out of the housing of the lawnmower.

[0006] The present invention aims to reduce the occurrence of a situation in which small stones or the like on the ground are kicked off by the base of a mower blade for a mower and fly out of the housing of the mower. [Means for solving the problem]

[0007] The walk-behind brush cutter of the present invention comprises a first cutting blade that is driven to rotate around a first vertical axis along the vertical direction, a first housing that houses the first cutting blade, a second cutting blade that is driven to rotate around a second vertical axis along the vertical direction, and a second housing that houses the second cutting blade, the first housing and the second housing being arranged side by side along the left-right direction, the second housing being supported by the first housing so that its position can be changed up and down around the front-to-back axis along the front-to-back direction, the rotation directions of the first cutting blade and the second cutting blade being set so that the first cutting blade and the second cutting blade move rearward at the position of the front-to-back axis, and the connection portion between the side surface portion of the first housing on the opposite side of the front-to-back axis and the rear surface portion of the first housing is formed so as to follow the rotation trajectory of the outer periphery of the first cutting blade in a planar view.

[0008] In the present invention, it is preferable that the connection portion between the lateral surface portion of the second housing on the opposite side of the front-to-rear axis and the rear surface portion of the second housing is formed so as to follow the rotational trajectory of the outer periphery of the second cutting blade in a planar view.

[0009] In the present invention, it is preferable that the diameter of the rotation locus of the outer periphery of the second cutting blade be larger than the diameter of the rotation locus of the outer periphery of the first cutting blade.

[0010] In the present invention, the first cutting blade and the second cutting blade are rotationally driven around the first vertical axis and the second vertical axis, and include a base having a first extending portion extending in one direction from the first vertical axis and a second extending portion extending in the other direction from the first vertical axis, a first cutting blade portion attached so as to be freely swingable around the first axis along the vertical direction of an end of the first extending portion, and a second extending portion attached so as to be freely swingable around the second axis along the vertical direction of an end of the second extending portion. and a second cutting blade portion that can be attached to the first cutting blade and the second cutting blade, and it is preferable that the length from the first axis to the outer end of the first cutting blade portion and the length from the second axis to the outer end of the second cutting blade portion are the same in the first cutting blade portion and the second cutting blade portion of the first and second cutting blades, and that the length from the first axis to the second axis at the base of the second cutting blade is longer than the length from the first axis to the second axis at the base of the first cutting blade.

[0011] In the present invention, the first cutting blade and the second cutting blade are rotatably driven around the first vertical axis and the second vertical axis, and have a base having a first extension portion extending in one direction from the first vertical axis and a second extension portion extending in the opposite direction from the first vertical axis, a first cutting blade portion attached so as to be freely swingable around the first axis along the vertical direction of the end of the first extension portion, and a second cutting blade portion attached so as to be freely swingable around the second axis along the vertical direction of the end of the second extension portion, and it is preferable that in the first cutting blade and the second cutting blade, the first extension portion and the second extension portion are configured in a tapered shape in a planar view so that their width becomes smaller toward the radially outer portion, and that the first cutting blade portion and the second cutting blade portion are configured in a flared shape in a planar view so that their width becomes larger toward the radially outer portion.

[0012] In the present invention, it is preferable that the width of the second housing in the left-right direction is greater than the width of the first housing in the left-right direction.

[0013] In the present invention, it is preferable that a front wheel is provided in front of the first housing and supports the first housing, and a rear wheel is provided behind the first housing and supports the first housing, and that the front wheel is capable of changing its position between a straight-ahead position in which the front wheel rotates along the fore-and-aft direction, and an inclined position in which the front wheel rotates along an imaginary direction extending diagonally forward from the first housing on the opposite side of the second housing in the fore-and-aft direction.

[0014] In the present invention, it is preferable that an engine is provided, and power of the engine is transmitted to the front wheels and the rear wheels to rotate the front wheels and the rear wheels.

[0015] In the present invention, it is preferable that an auxiliary wheel is provided in front of the second housing and supports the second housing, and that the auxiliary wheel is capable of changing its posture between a straight posture in which the front wheel rotates along the fore-and-aft direction and an inclined posture in which the auxiliary wheel rotates along an imaginary direction extending diagonally forward from the second housing toward the first housing in the fore-and-aft direction.

[0016]

[0017]

[0018]

[0019]

[0020]

[0021]

[0022] [Brief explanation of the drawings]

[0023] [Figure 1] FIG. [Figure 2]FIG. 1 is a plan view of a walk-behind brush cutter. [Figure 3] 3 is a schematic diagram showing a transmission system to the front and rear wheels, the first cutting blade, and the second cutting blade. FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. 2 is a rear view of the first housing and the second housing. [Figure 7] FIG. 4 is a longitudinal sectional rear view of the first housing and the second housing. [Figure 8] FIG. 2 is a bottom view of the first housing and the second housing. [Figure 9] FIG. 2 is a plan view of a first cutting blade. [Figure 10] FIG. 4 is a plan view of a second cutting blade. [Figure 11] FIG. 2 is an exploded perspective view of a first cutting blade and a second cutting blade. [Figure 12] FIG. 2 is an exploded perspective view of the vicinity of a second housing and an auxiliary wheel. [Figure 13] FIG. 4 is an exploded perspective view of a second housing. [Figure 14] FIG. 4 is a vertical sectional left side view of the second housing. [Figure 15] FIG. 10 is a longitudinal rear view showing a configuration for setting the left and right inclined postures of the support base, the support member, and the auxiliary wheels. [Figure 16] FIG. 10 is a plan view showing a configuration for setting the left and right tilt attitudes of the support base, the support member, and the auxiliary wheels. [Figure 17] FIG. 1 is a perspective view showing the state of mowing work on a ridge using a walk-behind mower. DETAILED DESCRIPTION OF THE INVENTION

[0024] 1 to 17 show a walk-behind mower equipped with a first cutting blade 11 and a second cutting blade 12, where F indicates the forward direction, B indicates the backward direction, U indicates the upward direction, D indicates the downward direction, R indicates the right direction, and L indicates the left direction.

[0025] (Overall configuration of a walk-behind lawnmower) As shown in Figures 1 and 2, the walk-behind mower has a first housing 21 that houses a first cutting blade 11, a second housing 22 that houses a second cutting blade 12, a front wheel 1 and a rear wheel 2 attached to the first housing 21, an engine 3, a steering handle 4, an auxiliary wheel 33 attached to the second housing 22, and the like.

[0026] (Configuration of the first housing) As shown in Figures 2, 6, 7, 8, and 12, the first housing 21 has a top panel portion 23, a vertical surface portion 24 located on the right side of the first housing 21, a fixed vertical side member 25 which is the rear surface of the first housing 21, a cover 27, etc.

[0027] The vertical panel 24 is connected to the right part of the top panel 23 with bolts and can be replaced with another vertical panel 24 by removing the bolts. The fixed vertical side member 25 is connected to the rear part of the top panel 23 with bolts and can be replaced with another fixed vertical side member 25 by removing the bolts. The cover 27 is made of a flexible rubber plate and is attached to the right and left parts of the front of the top panel 23.

[0028] As shown in FIG. 8, the vertical surface portion 24 has a front portion 24a and a rear portion 24b, and is bent at its middle portion so that the direction of the front portion 24a and the direction of the rear portion 24b intersect.

[0029] The front part 24a of the vertical surface part 24 forms the horizontal surface part on the opposite side of the axis P3 of the first housing 21 (see (Configuration of the Second Housing) described below), and the rear part 24b of the vertical surface part 24 forms the connection part between the front part 24a of the vertical surface part 24 and the fixed vertical side member 25 which is the rear part of the first housing 21. The rear part 24b of the vertical surface part 24 is formed so as to follow the rotation trajectory C1 of the outer periphery of the first cutting blade 11 in a plan view (see (State of the First Cutting Blade and the Second Cutting Blade) described below).

[0030] (Configuration of the second housing) As shown in FIGS. 2, 6, 7, 8, 12, and 13, the second housing 22 has a top plate portion 28, a vertical surface portion 29, a vertical side member 30 which is an opening area changing portion, a cover 31, a guard member 32, auxiliary wheels 33, and the like.

[0031] 6, 8, 12, and 13, the vertical surface portion 29 has a horizontal surface portion 29a located on the left side of the second housing 22, a rear surface portion 29b located on the rear side of the second housing 22, and an intermediate portion 29c. The vertical surface portion 29 is connected to the top plate portion 28 with bolts, and can be replaced with another vertical surface portion 29 by removing the bolts.

[0032] The vertical side member 30 is attached to the rear surface 29b of the vertical surface portion 29 by a bolt 34, which is an opening area changing portion and a position changing portion, and can be replaced with another vertical side member 30 by removing the bolt 34.

[0033] 2, the cover 31 is made of a flexible rubber plate and is attached to the front of the top plate 28. The guard member 32 is made of a round bar and is attached to the front of the top plate 28.

[0034] As shown in Figures 2, 6, 7, and 8, the right part of the top plate portion 28 is attached to the left part of the top plate portion 23 so that it can swing up and down around the axis P3, and the second housing 22 is supported on the left part of the first housing 21 so that its position can be changed up and down around the axis P3, which is the front-to-back axis along the front-to-back direction.

[0035] A wire (not shown) is connected between the angle adjustment lever 13 (described later in "Configuration of the Steering Handle" and FIG. 2) provided on the steering handle 4 and the second housing 22. The angle adjustment lever 13 allows the second housing 22 to be set to a horizontal position parallel to the first housing 21, or a downward position facing diagonally downward from the first housing 21 (see FIGS. 6 and 7).

[0036] A plurality of downward positions with different angles can be set by using the angle adjustment lever 13. In this case, in each of the plurality of downward positions, the second housing 22 is prevented from swinging downward from the set angle and is allowed to swing upward from the set angle.

[0037] As shown in Figures 8 and 13, in the vertical surface portion 29, the horizontal surface portion 29a of the vertical surface portion 29 becomes the horizontal surface portion on the opposite side of the axis P3 of the second housing 22, the rear surface portion 29b of the vertical surface portion 29 becomes the rear surface portion of the second housing 22, and the middle portion 29c of the vertical surface portion 29 becomes the connection portion between the horizontal surface portion 29a and the rear surface portion 29b of the vertical surface portion 29.

[0038] The intermediate portion 29c of the vertical surface portion 29 is formed in an arc shape when viewed in a plane, and the intermediate portion 29c of the vertical surface portion 29 is formed to follow the rotational trajectory C2 of the outer periphery of the second cutting blade 12 when viewed in a plane (see (State of the first cutting blade and the second cutting blade) described below).

[0039] (Engine, steering handle, and rear wheel support configuration) As shown in FIGS. 2, 6 and 8, in the first housing 21, the frame 5 is connected to the rear part of the top plate portion 23 along the left-right direction, and the engine 3 is supported by the frame 5.

[0040] A frame 6 is connected to the right part of the frame 5 in the vertical direction, and an angled frame 7 is connected to the left part of the frame 5 in the vertical direction. A handle base 8 is connected to the frame 7 in the vertical direction, and a steering handle 4 is attached to the handle base 8. The steering handle 4 is attached to the first housing 21 via the handle base 8 so as to extend rearward from the first housing 21.

[0041] 1 and 2, a rear wheel support case 9 is provided, and a rear wheel 2 is supported on the lower part of the rear wheel support case 9. An upper part of the rear wheel support case 9 is connected to the handle base 8, a front part of the rear wheel support case 9 is connected to an upper part of the frame 6 via a bracket 10, and a lower part of the rear wheel support case 9 is connected to the right part of the frame 5 and the lower part of the frame 6. As described above, the rear wheel 2 supporting the first housing 21 is attached to the first housing 21 so as to be located behind the first housing 21.

[0042] (Control handle configuration) 1 and 2, the steering handle 4 has a right handle portion 81 and a left handle portion 82 made of round pipes. The right handle portion 81 has a right first portion 81a, a right second portion 81b, and a right holding portion 81c, and the left handle portion 82 has a left first portion 82a, a left second portion 82b, and a left holding portion 82c.

[0043] The right first portion 81a of the right handle portion 81 extends diagonally rearward and rightward from the handle base 8 (first housing 21) in a plan view, and extends diagonally rearward and upward in a side view. A hook portion 81f is connected to the rear surface of the right first portion 81a.

[0044] In a plan view, the right second portion 81b of the right handle portion 81 extends from the rear portion 81d of the right first portion 81a diagonally rearward to the right, slightly toward the center of the steering handle 4 from the direction of extension of the right first portion 81a, and in a side view, extends approximately horizontally rearward from the rear portion 81d of the right first portion 81a.

[0045] The right handle portion 81c of the right handle section 81 extends rearward in the fore-and-aft direction from the rear portion 81e of the right second section 81b in a plan view, and extends rearward approximately horizontally from the rear portion 81e of the right second section 81b in a side view.

[0046] The left first portion 82a of the left handle portion 82 extends diagonally left rearward from the handle base 8 (first housing 21) in a plan view, and extends diagonally upward rearward in a side view. A hook portion 82f is connected to the rear surface of the left first portion 82a.

[0047] In a plan view, the left second portion 82b of the left handle portion 82 extends from the rear portion 82d of the left first portion 82a diagonally rearward to the left, slightly toward the center of the steering handle 4 from the direction of extension of the left first portion 82a, and in a side view, extends approximately horizontally rearward from the rear portion 82d of the left first portion 82a.

[0048] The left grip portion 82c of the left handle portion 82 extends rearward in the fore-and-aft direction from the rear portion 82e of the left second portion 82b in a plan view, and extends rearward approximately horizontally from the rear portion 82e of the left second portion 82b in a side view.

[0049] The right handle portion 81 is provided with the angle adjustment lever 13, the speed change lever 55, the mowing clutch lever 72, and the accelerator lever 83 for the engine 3. The left handle portion 82 is provided with the positioning lever 37, the traveling clutch lever 56, and the stop switch 84 for the engine 3.

[0050] (Steering wheel status) 1 and 2, an operator standing behind the walk-behind brush cutter holds the right handle portion 81c of the right handle portion 81 and the left handle portion 82c of the left handle portion 82. In this case, the left-right distance W1 between the right handle portion 81c of the right handle portion 81 and the left handle portion 82c of the left handle portion 82 is determined almost uniquely by the general physique of the operator, etc.

[0051] As described above (Configuration of the steering handle), the left-right distance W2 between the rear 81d of the right first part 81a of the right handle part 81 and the rear 82d of the left first part 82a of the left handle part 82 is large and close to the distance W1.

[0052] As described below in (Operations for changing the attitude of the support members and auxiliary wheels), when setting the tilted attitude of the support members 46 and the support base 45 (auxiliary wheels 33) or when changing the attitude of the support members 46 up or down, an operator standing behind the walk-behind brush cutter can easily fit his or her body between the right handle portion 81 and the left handle portion 82 of the steering handle 4.

[0053] This allows the operator to easily set the tilt position of the support member 46 and the support base 45 (auxiliary wheel 33) or change the position of the support member 46 up or down by extending their hands forward.

[0054] When the walk-behind brush cutter is mounted on the bed of a truck (not shown) for transport, the walk-behind brush cutter can be secured to the bed of the truck by attaching a rope between the hook portion of the bed of the truck and the hook portions 81f, 82f of the steering handle 4 (right handle portion 81 and left handle portion 82).

[0055] (Configuration for supporting the front wheels in the left and right direction) 4 and 5, the front wheel support member 14 is provided in the front portion of the top plate portion 23 of the first housing 21. The front wheel support member 14 is formed by bending a plate material, and the right portion of the base plate portion 14a of the front wheel support member 14 is attached to the top plate portion 23 so that its orientation can be changed left and right around an axis P4 that extends in the up-down direction.

[0056] A long hole 14b extending in the front-to-rear direction is opened in the left part of the base plate portion 14a of the front wheel support member 14. A bolt 15 fixed facing upward to the top plate portion 23 is inserted into the long hole 14b of the front wheel support member 14, and a fixed handle 16 having a female thread portion is attached to the bolt 15.

[0057] Right and left support portions 14c are provided on a base portion 14a of the front wheel support member 14, and a front wheel support case 17 is supported so as to be swingable up and down about an axis P5 along the left-right direction. As shown in Figures 1 and 2, the front wheel support member 14 passes between covers 27 (see the above-mentioned (Configuration of the first housing)) and extends forward, and the front wheel 1 is supported at the front portion of the front wheel support case 17.

[0058] As shown in Figures 2 and 5, within the range of the long hole 14b of the front wheel support member 14, the posture of the front wheel support case 17 and the front wheel support member 14 can be changed left and right between a straight-ahead posture A11 in which the front wheel 1 rotates along the fore-and-aft direction in a planar view, and an inclined posture A12 in which the front wheel 1 rotates along an imaginary direction extending diagonally forward on the opposite side of the second housing 22 from the fore-and-aft direction.

[0059] The worker can fix the posture of the front wheel support member 14 by turning the fixing handle 16 and tightening the base plate portion 14a of the front wheel support member 14. By turning the fixed handle 16 and loosening the fastening of the base portion 14a of the front wheel support member 14, the operator can change the posture of the front wheel support case 17 and the front wheel support member 14 left and right within the range of the long hole 14b of the front wheel support member 14, and can set the inclined posture of the front wheel support case 17 and the front wheel support member 14 (front wheel 1) to any position between the straight-ahead posture A11 and the inclined posture A12.

[0060] (Configuration for supporting the front wheels in the vertical direction) As shown in Figures 4 and 5, a positioning member 18 is connected to the front wheel support case 17 and extends rearward, a positioning member 19 is connected to the rear of the positioning member 18, and three locking holes 19a are opened in the positioning member 19 so as to be aligned in the vertical direction.

[0061] A cylindrical member 20 is connected to the front wheel support member 14. A positioning pin 35 is provided on the cylindrical member 20 so as to be slidable along the front-to-rear direction, and a spring 36 is provided to bias the positioning pin 35 in the protruding direction, and a wire 38 is connected between a positioning lever 37 (see the above-mentioned (Configuration of the steering handle) and Figure 2) and the positioning pin 35.

[0062] While holding the steering handle 4, the operator operates the positioning lever 37 to remove the positioning pin 35 from the locking hole 19a of the positioning member 19, and moves the front part of the first housing 21 up and down using the rear wheel 2 as a fulcrum. Because the front wheel 1 is in contact with the ground due to the weight of the front wheel 1 and the front wheel support case 17, the attitude of the front wheel support case 17 relative to the first housing 21 changes up and down.

[0063] When the front of the first housing 21 reaches the desired height, the operator can operate the positioning lever 37 and insert the positioning pin 35 into one of the locking holes 19a of the positioning member 19, thereby setting the posture of the front wheel support case 17 relative to the first housing 21 in three positions up or down, and setting the cutting height of the first cutting blade 11 to the desired height. As described above, the front wheel 1 supporting the first housing 21 is attached to the first housing 21 so as to be located in front of the first housing 21.

[0064] (Configuration related to auxiliary wheels) As shown in Figures 2, 12, and 14, the second housing 22 is provided with a support base 45, which is a position-changing part formed by bending a plate material into a channel shape, and the support base 45 is attached to the top plate portion 28 so that its position can be changed left and right around axis P6, which is an up-down axis along the vertical direction.

[0065] A round pipe-shaped support member 46 is provided, and is attached to a support base 45 so that its position can be changed up and down around an axis P7 that extends in the left-right direction. The support member 46 is attached to the second housing 22 via the support base 45 so as to protrude forward from the second housing 22, and the auxiliary wheel 33 is attached to the front end of the support member 46 so as to be located in front of the second housing 22.

[0066] A lock lever 47 is attached to the rear of the support member 46 so as to be able to swing up and down around an axis P8 that extends in the left-right direction, and the up and down position of the support member 46 can be fixed by engaging a pin 47a of the lock lever 47 with one of a plurality of engaging portions 45a of the support base 45. A spring 48 is connected between the lock lever 47 and the support member 46, and the spring 48 biases the lock lever 47 toward the side where the pin 47a of the lock lever 47 engages with the engaging portion 45a of the support base 45.

[0067] 2, 12, 15, and 16, the base member 49 is fixed to a portion of the top panel 28 immediately to the right of the rear part of the support base 45, and a nut 49a is fixed to the upper part of the base member 49. A flat fixing member 50, which is an attitude changing part and a fixing part, is connected to the right part of the rear part of the support base 45 and extends rightward from the support base 45 so as to be located above the base member 49.

[0068] A long hole 50a is opened in the fixed member 50, and a right end portion 50b of the fixed member 50 is bent downward. A fixed handle 51, which is a position changing portion and a fixed portion, is provided, and a male screw portion is provided at the bottom of the fixed handle 51.

[0069] (Operations for changing the position of the support member and auxiliary wheels) As shown in Figures 2, 12, 15, and 16, the support base 45 can change its position left and right around the axis P6 within the range where the rear of the support base 45 abuts the left part of the base member 49 and the end 50b of the fixing member 50 abuts the right part of the base member 49.

[0070] As a result, as shown in FIG. 2, in a plan view, the postures of the support member 46 and the support base 45 can be changed left and right across a straight posture A21 (a position where the rear part of the support base 45 abuts the left part of the base member 49) in which the auxiliary wheel 33 rotates along the fore-and-aft direction, and an inclined posture A22 (a position where the end part 50b of the fixing member 50 abuts the right part of the base member 49) in which the auxiliary wheel 33 rotates along an imaginary direction extending diagonally forward on the first housing 21 side relative to the fore-and-aft direction.

[0071] As shown in Figures 2, 12, 15, and 16, the male threaded portion of the fixed handle 51 can be attached to the nut 49a of the base member 49 through the long hole 50a of the fixing member 50, and the fixing handle 51 can be turned to tighten the fixing member 50, thereby fixing the support base 45 to the second housing 22.

[0072] The operator can release the fixation of the support base 45 by turning the fixed handle 51 to loosen the fastening of the fixing member 50, and change the posture of the support member 46 and the support base 45 to the left or right. By turning the fixed handle 51 to fasten the fixing member 50, the tilt posture of the support member 46 and the support base 45 (auxiliary wheels 33) can be set to any position between the straight posture A21 and the tilt posture A22.

[0073] The operator can change the position of the support member 46 up or down by gripping the rear portion of the support member 46 and the lock lever 47 and removing the pin 47a of the lock lever 47 from the engaging portion 45a of the support base 45. By engaging the pin 47a of the lock lever 47 with the desired engaging portion 45a of the support base 45, the cutting height of the second cutting blade 12 can be set to the desired height.

[0074] (Transmission structure to front and rear wheels) 1, 2, and 3, a transmission 53 is provided on the upper part of the rear wheel support case 9. A transmission belt 54 is attached between a pulley 3b of an output shaft 3a of the engine 3 and a pulley 53b of an input shaft 53a of the transmission 53.

[0075] The transmission 53 is equipped with a traveling clutch (not shown) and is configured to be able to shift between three forward gears and one reverse gear. A wire (not shown) is connected between the transmission lever 55 (see the above-mentioned (Configuration of the steering handle) and Figures 1 and 2) and the transmission 53, and the transmission lever 55 can be used to operate the transmission 53 between three forward gears and one reverse gear.

[0076] In the transmission 53, the traveling clutch is biased to a disengaged state, and a wire (not shown) is connected between the traveling clutch lever 56 (see the above-mentioned (Configuration of the steering handle) and Figure 2) and the traveling clutch. When the operator grips the traveling clutch lever 56 and pulls the wire toward the traveling clutch lever 56, the traveling clutch is operated into a transmission state, and when the operator releases the traveling clutch lever 56, the traveling clutch is operated into a disengaged state.

[0077] Inside the rear wheel support case 9, a transmission chain 58 is attached between a sprocket 53d of the output shaft 53c of the transmission 53 and a sprocket 57a of an axle 57 that supports the rear wheel 2. A transmission shaft 59 is provided in the vertical middle part of the rear wheel support case 9, and a sprocket 59a of the transmission shaft 59 is in mesh with the transmission chain 58.

[0078] As shown in FIGS. 1 to 5, a transmission shaft 63 is supported on the right front portion of the first housing 21, and a transmission chain 64 is attached between a sprocket 59b of the transmission shaft 59 and a sprocket 63a of the transmission shaft 63.

[0079] An input shaft 65 of the front wheel support case 17 is disposed at the position of the axis P5, and the input shaft 65 and the transmission shaft 63 are connected via a universal joint 66. Inside the front wheel support case 17, a transmission chain 68 is attached between a sprocket 65a of the input shaft 65 and a sprocket 67a of an axle 67 that supports the front wheel 1.

[0080] With the above configuration, as shown in Fig. 3, the power of the engine 3 is transmitted to the transmission 53 via the transmission belt 54. The power, whose speed has been changed by the transmission 53, is transmitted to the rear wheel 2 via the transmission chain 58, and is then transmitted to the front wheel 1 via the transmission chain 58, the transmission shaft 59, the transmission chain 64, the transmission shaft 63, the input shaft 65, and the transmission chain 68. When the running clutch of the transmission 53 is disengaged, the front wheel 1 and the rear wheel 2 stop.

[0081] In this case, the universal joint 66 is positioned so as to be located on an extension line of the axis P4, so that, as described above (Configuration for supporting the front wheels in the left-right direction), even if the position of the front wheel support case 17 and the front wheel support member 14 is changed left and right around the axis P4, power is transmitted smoothly from the transmission shaft 63 to the input shaft 65.

[0082] (Configuration of the first cutting blade and the second cutting blade) As shown in FIGS. 9, 10, and 11, the first cutting blade 11 and the second cutting blade 12 each have a base 60 that is elongated and diamond-shaped in plan view, two first cutting blade portions 61, and two second cutting blade portions 62.

[0083] A large opening 60e is formed in the center of the base 60, and openings 60f are formed on both sides of the opening 60e. The base 60 is provided with a first extending portion 60a extending in one direction from the opening 60e, and a second extending portion 60b extending in the opposite direction from the opening 60e.

[0084] In this case, the length of the base 60 of the second cutting blade 12 (the length extending from the end of the first extension portion 60a to the end of the second extension portion 60b) is configured to be longer than the length of the base 60 of the first cutting blade 11 (the length extending from the end of the first extension portion 60a to the end of the second extension portion 60b).

[0085] In the base 60, one edge of the first extending portion 60a and the opposite edge of the second extending portion 60b are formed into an inclined surface 60c, and the other edge of the first extending portion 60a and the opposite edge of the second extending portion 60b are formed into an inclined surface 60d. In Fig. 10, the inclined surface 60c of the base 60 faces diagonally downward, and the inclined surface 60d of the base 60 faces diagonally upward.

[0086] In the first cutting blade 11 and the second cutting blade 12, the four first cutting blade portions 61 and the four second cutting blade portions 62 are all configured to have the same shape, and cutting portions 61a, 61b, 62a, 62b are formed on both one and the other edge portions of the first cutting blade 11 and the second cutting blade 12.

[0087] In the first cutting blade 11, the first cutting blade portion 61 is attached to both the upper and lower sides of the first extending portion 60a of the base 60 by the support pins 52 so as to be able to freely swing around the axis P11, which is a first axis along the up-down direction. As a result, the first cutting blade portion 61 is provided on the first extending portion 60a of the base 60 so as to extend outward from the first extending portion 60a of the base 60.

[0088] In the second cutting blade 12, the second cutting blade portion 62 is attached to both the upper and lower sides of the second extending portion 60b of the base 60 by the support pins 52 so as to be able to freely swing around the axis P12, which is a second axis along the up-down direction. As a result, the second cutting blade portion 62 is provided on the second extending portion 60b of the base 60 so as to extend outward from the second extending portion 60b of the base 60.

[0089] (Configuration related to support of first cutting blade and second cutting blade) 2, 6, 7, and 8, in the first housing 21, the blade case 26 is connected to the top plate 23. The drive shaft 41 is supported by the blade case 26 so as to be rotatable around an axis P1, which is a first vertical axis along the up-down direction, and a bracket 41a is connected to the lower part of the drive shaft 41 by a nut 39.

[0090] In the second housing 22, a blade case 43 is connected to the top plate 28. A drive shaft 42 is supported by the blade case 43 so as to be rotatable around an axis P2, which is a second vertical axis along the up-down direction, and a bracket 42a is connected to the lower part of the drive shaft 42 by a nut 39.

[0091] 7 and 8, a cylindrical cover 44 with a bottom is provided. In the first housing 21, the bottom of the cover 44 is sandwiched between the base 60 of the first cutting blade 11 and the bracket 41a of the drive shaft 41, and the nut 39 is inserted into the opening 60e (see FIG. 11) of the base 60 of the first cutting blade 11, and the bolt 40 is connected through the opening 60f (see FIG. 11) of the base 60 of the first cutting blade 11 and the bracket 41a of the drive shaft 41, thereby attaching the first cutting blade 11 and the cover 44 to the lower part of the drive shaft 41.

[0092] In the second housing 22, the bottom of the cover 44 is sandwiched between the base 60 of the second cutting blade 12 and the bracket 42a of the drive shaft 42, and the nut 39 is inserted into the opening 60e (see Figure 11) of the base 60 of the second cutting blade 12, and the bolt 40 is connected through the opening 60f (see Figure 11) of the base 60 of the second cutting blade 12 and the bracket 42a of the drive shaft 42, thereby attaching the second cutting blade 12 and the cover 44 to the bottom of the drive shaft 42.

[0093] With the above configuration, in the first cutting blade 11 and the second cutting blade 12, the base 60 is attached to the lower part of the drive shafts 41, 42, and the base 60 has a first extension part 60a extending in one direction from the lower part of the drive shafts 41, 42, and a second extension part 60b extending in the opposite direction from the lower part of the drive shafts 41, 42.

[0094] For the first cutting blade 11 and the second cutting blade 12, the bolt 40 can be removed, the base 60 can be removed from the brackets 41a, 42a of the drive shafts 41, 42, the first cutting blade 11 and the second cutting blade 12 can be turned upside down, and the base 60 can be reattached to the brackets 41a, 42a of the drive shafts 41, 42 with the bolt 40, and the first cutting blade 11 and the second cutting blade 12 can be attached to the lower part of the drive shafts 41, 42.

[0095] As described below (Transmission structure to the first cutting blade and the second cutting blade) and shown in Figures 8, 9, and 10, the first cutting blade 11 is rotationally driven in a rotational direction B1, and the second cutting blade 12 is rotationally driven in a rotational direction B2. The rotational direction B1 is counterclockwise when the first housing 21 is seen in a plan view, and the rotational direction B2 is clockwise when the second housing 22 is seen in a plan view.

[0096] With the above configuration, the first cutting blade 11 is rotatably supported about axis P1, which is a first vertical axis along the vertical direction, and is housed in the first housing 21. The second cutting blade 12 is rotatably supported about axis P2, which is a second vertical axis along the vertical direction, and is housed in the second housing 22.

[0097] (State of the first and second cutting blades) As shown in Figures 9 and 10, the length of the base 60 of the second cutting blade 12 is longer than the length of the base 60 of the first cutting blade 11 (see the previous section (Configuration of the first cutting blade and the second cutting blade)), and therefore the diameter D2 of the rotational trajectory C2 of the second cutting blade 12 is larger than the diameter D1 of the rotational trajectory C1 of the first cutting blade 11.

[0098] Below the connecting portion (axial center P3) between first housing 21 and second housing 22, rotation locus C1 of first cutting blade 11 and rotation locus C2 of second cutting blade 12 partially overlap in a plan view.

[0099] Since the four first cutting blade portions 61 and the four second cutting blade portions 62 are all configured to have the same shape (see the above-mentioned (Configuration of the first cutting blades and second cutting blades)), the length L11 extending from the axis P11 to the outer end of the first cutting blade portion 61 and the length L12 extending from the axis P12 to the outer end of the second cutting blade portion 62 are the same for the first cutting blade 11 and the second cutting blade 12.

[0100] In the first cutting blade 11, the length L21 between the axis P1 and axis P11 of the drive shaft 41 and the length L22 between the axis P1 and axis P12 of the drive shaft 41 are the same length, and L11 and L12 are set to be longer than lengths L21 and L22.

[0101] In the second cutting blade 12, the length L31 between the axis P2 and axis P11 of the drive shaft 42 and the length L32 between the axis P2 and axis P12 of the drive shaft 42 are the same length, and L31, L32 are set to be longer than lengths L11, L12.

[0102] 8 to 11, the first cutting blade 11 and the second cutting blade 12 are rotationally driven in the rotation directions B1 and B2, so that cutting edges 61a, 61b, 62a, and 62b are formed on both the upstream and downstream edges of the first cutting blade portion 61 and the second cutting blade portion 62 in the rotation directions B1 and B2. The upstream and downstream edges of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotation directions B1 and B2 are formed into inclined surfaces 60c and 60d.

[0103] The upstream edge of the first extension portion 60a of the base 60 in the rotation directions B1 and B2 and the upstream edge of the second extension portion 60b of the base 60 in the rotation directions B1 and B2 are formed into an inclined surface 60c that is diagonally downward with respect to the rotation directions B1 and B2.

[0104] The edge portion on the downstream side in the rotation directions B1, B2 of the first extension portion 60a of the base 60 and the edge portion on the downstream side in the rotation directions B1, B2 of the second extension portion 60b of the base 60 are formed into an inclined surface 60d that is diagonally upward with respect to the rotation directions B1, B2.

[0105] As described above (Configuration for supporting the first cutting blade and the second cutting blade), when the first cutting blade 11 and the second cutting blade 12 are attached upside down to the bottom of the drive shafts 41, 42, the upstream edge and the downstream edge in the rotation directions B1, B2 of the first extension portion 60a of the base 60 are swapped, and the upstream edge and the downstream edge in the rotation directions B1, B2 of the second extension portion 60b of the base 60 are swapped.

[0106] As a result, the upstream edge portions of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotation directions B1 and B2 become diagonally downward inclined surfaces 60d, and the downstream edge portions of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotation directions B1 and B2 become diagonally upward inclined surfaces 60c.

[0107] (Power transmission structure to the first and second cutting blades) 1, 2, 3, and 7, in the first housing 21, the transmission shaft 69 is supported by the blade case 26, and a transmission belt 70 is attached between the pulley 3c of the output shaft 3a of the engine 3 and the pulley 69a of the transmission shaft 69. Inside the blade case 26, the bevel gear 41b of the drive shaft 41 and the bevel gear 69b of the transmission shaft 69 are engaged with each other.

[0108] A tension pulley type mowing clutch 71 is provided for the transmission belt 70. A wire (not shown) is connected between the mowing clutch lever 72 (see the above-mentioned (Configuration of the steering handle) and Figures 1 and 2) and the mowing clutch 71, and the mowing clutch lever 72 can be used to operate the mowing clutch 71 between a transmission state and a disengagement state.

[0109] In the second housing 22, the transmission shaft 73 is supported by the blade case 43, and the transmission shaft 69 and the transmission shaft 73 are connected via two universal joints 74 and an extendable transmission shaft 75. Inside the blade case 43, the bevel gear 42b of the drive shaft 42 and the bevel gear 73a of the transmission shaft 73 are engaged with each other.

[0110] As shown in Figures 1, 2, and 3, a metal cover 76 is attached to the first housing 21, and the cover 76 covers the output shaft 3a and pulleys 3b and 3c of the engine 3, the transmission belt 54, the input shaft 53a and pulley 53b of the transmission 53, the transmission shaft 59 (sprocket 59b), the transmission chain 64, the transmission shaft 63 (sprocket 63a), the transmission shaft 69 (pulley 69a), the transmission belt 70, the mowing clutch 71, etc.

[0111] As shown in Figures 2, 6, and 7, an expandable and flexible cylindrical cover 77 is attached across the cutting blade case 26 and the cutting blade case 43, and a universal joint 74 and a transmission shaft 75 are housed inside the cover 77.

[0112] With the above configuration, as shown in FIG. 3, the power of the engine 3 is transmitted to the drive shaft 41 via the transmission belt 70 and the transmission shaft 69, and then to the drive shaft 42 via the transmission shaft 69, the universal joint 74, the transmission shaft 75, and the transmission shaft 73.

[0113] 8, 9, and 10, the drive shaft 41 and the first cutting blade 11 are rotationally driven in a rotational direction B1, and the drive shaft 42 and the second cutting blade 12 are rotationally driven in a rotational direction B2, and the rotational trajectories C1, C2 and the rotational directions B1, B2 are set so that the first cutting blade 11 and the second cutting blade 12 move rearward at the position of the axis P3. When the cutting clutch 71 is operated to the disengaged state, the first cutting blade 11 and the second cutting blade 12 stop.

[0114] In this case, as described above (Configuration of the second housing), even if the position of the second housing 22 is changed up or down, power is transmitted smoothly from the transmission shaft 69 to the transmission shaft 73 by the bending of the universal joint 74 and the extension and contraction of the transmission shaft 75.

[0115] (Configuration of the opening for discharging grass clippings cut by the first and second cutting blades) As shown in FIGS. 6, 8 and 12, in the first housing 21, the left end of the fixed vertical side member 25 is located closer to the left-right center of the first housing 21 than the left end of the top panel portion 23 (closer to the drive shaft 41).

[0116] As a result, an opening 78 through which grass clippings can be discharged rearward is formed in the portion of fixed vertical side member 25 of first housing 21 adjacent to second housing 22, so as to be located rearward of axis P3 (the connection portion between first housing 21 and second housing 22). Opening 78 is provided so as to be located on the left side, which is the side of second housing 22, with respect to rear wheel 2 in rear view and plan view (see FIG. 2).

[0117] In a plan view, the left rear portion of the top plate portion 23 of the first housing 21 and the fixed vertical side member 25 are located forward of the vertical side member 30 of the second housing 22. In a rear view, the left rear portion of the top plate portion 23 of the first housing 21 and the fixed vertical side member 25, and the vertical side member 30 of the second housing 22 form the outer periphery of the opening 78.

[0118] The vertical side portion 25a of the fixed vertical side member 25 is the right vertical side portion on the rear wheel 2 side of the right and left vertical side portions of the opening 78. In rear view, the vertical side portion 25a of the fixed vertical side member 25 is disposed at an angle so that the lower part of the vertical side portion 25a of the fixed vertical side member 25 is laterally outwardly spaced from the left-right center of the opening 78 (so as to be located on the rear wheel 2 side) than the upper part of the vertical side portion 25a of the fixed vertical side member 25.

[0119] The extension portion 25b of the fixed vertical side member 25 extends diagonally from the vertical side portion 25a of the fixed vertical side member 25 toward the rear and the left-right center of the opening 78, and the extension portion 25b of the fixed vertical side member 25 is an extension portion provided on the right vertical side portion of the opening 78.

[0120] The vertical side portion 30a of the vertical side member 30 is the left vertical side portion on the opposite side of the rear wheel 2 among the right and left vertical side portions of the opening 78. The vertical side portion 30a of the vertical side member 30 is disposed at an angle in rear view so that the lower part of the vertical side portion 30a of the vertical side member 30 is further outward laterally from the center of the opening 78 than the upper part of the vertical side portion 30a of the vertical side member 30 in rear view (so as to be located on the opposite side of the rear wheel 2).

[0121] The extension portion 30b of the vertical side member 30 extends diagonally from the vertical side portion 30a of the vertical side member 30 toward the rear and the left-right center of the opening 78, and the extension portion 30b of the vertical side member 30 is an extension portion provided on the right vertical side portion of the opening 78.

[0122] As described above in (Configuration of the second housing) and shown in Fig. 6, when the second housing 22 is set in a downward position facing diagonally downward from the first housing 21, the vertical side portion 30a and the extending portion 30b of the vertical side member 30 are in a nearly upright position. When the second housing 22 is set in a horizontal position parallel to the first housing 21, the vertical side portion 30a and the extending portion 30b of the vertical side member 30 are in an inclined position as described above.

[0123] 2 and 6, a bracket 79 is connected to the lower part of the frame 7 so as to face rearward. A flexible pressing member 80 made of a rubber plate is attached to the bracket 79 and extends diagonally downward and rearward. The pressing member 80 is disposed behind the opening 78.

[0124] (Configuration for changing the opening area of ​​the opening through which grass clippings cut by the first cutting blade and the second cutting blade are discharged) 6, 8, 12, and 13, a long hole 30c, which is an opening area changing portion and a position changing portion, is opened along the left-right direction in the vertical side member 30. A bolt 34 is inserted into the long hole 30c of the vertical side member 30 and tightened to the rear surface portion 29b of the vertical surface portion 29, thereby fixing the vertical side member 30 to the rear surface portion 29b of the vertical surface portion 29.

[0125] By loosening the bolts 34, the vertical side member 30 can be moved left and right relative to the rear surface 29b of the vertical surface portion 29. When the vertical side member 30 is moved leftward and away from the fixed vertical side member 25, the opening area of ​​the opening 78 increases, and when the vertical side member 30 is moved rightward and closer to the fixed vertical side member 25, the opening area of ​​the opening 78 decreases.

[0126] (Weeding work on the ridges) When mowing ridges with a walk-behind mower, as shown in Figures 6, 7, and 17, the first housing 21 is moved along the upper surface E1 of the ridge using the front wheels 1 and rear wheels 2, and the second housing 22 is moved along the slope E2 of the ridge using the auxiliary wheels 33, thereby mowing the upper surface E1 and slope E2 of the ridge.

[0127] As described above (Configuration related to support of the front wheels in the up-down direction) and as shown in Fig. 4, the vertical position of the front wheel support case 17 relative to the first housing 21 is set to set the cutting height of the first cutting blade 11. As described above (Operation related to changing the position of the support member and auxiliary wheel) and as shown in Fig. 14, the cutting height of the second cutting blade 12 is set by changing the position of the support member 46 up or down.

[0128] The front wheels 1 and rear wheels 2 are driven to rotate, and the first housing 21 receives forward driving force from the front wheels 1 and rear wheels 2, whereas the auxiliary wheels 33 are not driven to rotate, and therefore the second housing 22 does not receive forward driving force from the front wheels 1 and rear wheels 2. As a result, when the second housing 22 encounters resistance from the grass on the slope E2 of the ridge as the walk-behind mower moves forward, the second housing 22 may try to move downward toward the bottom of the slope E2 of the ridge, using the rear wheel 2 as a fulcrum (see arrow F1).

[0129] When the above-described situation occurs, as described above (operations related to changing the attitude of the support member and auxiliary wheels) and as shown in Figure 2, the left and right attitudes of the support member 46 and the support base 45 are set to the inclined attitude A22 or any inclined attitude between the straight-ahead attitude A21 and the inclined attitude A22.

[0130] As the walk-behind mower moves forward, the auxiliary wheels 33 rotate while in contact with the slope E2 of the ridge, attempting to climb diagonally upwards up the slope E2 of the ridge (see arrow F2), which generates a force (see arrow F3) that attempts to lift the second housing 22 to the upper side of the slope E2 of the ridge.

[0131] This prevents the second housing 22 from descending toward the lower side of the slope E2 of the ridge with the rear wheel 2 as a fulcrum due to the moment caused by the length (moment arm) of the support member 46 extending forward from the first housing 21 and the aforementioned force (arrow F3).

[0132] If simply setting the left and right postures of the support member 46 and the support base 45 to the inclined posture A22 is not enough to prevent the second housing 22 from descending toward the lower side of the slope portion E2 of the ridge, using the rear wheel 2 as a fulcrum, then as described above (configuration related to support of the front wheel in the left and right direction) and as shown in Figure 2, the left and right postures of the front wheel support case 17 and the front wheel support member 14 are set to the inclined posture A12 or any inclined posture between the straight-ahead posture A11 and the inclined posture A12.

[0133] This generates a force (see arrow F4) that causes the front wheel 1 to move the first housing 21 to the opposite side of the slope portion E2 of the ridge, and the second housing 22 tries to be pulled up to the upper surface portion E1 of the ridge via the first housing 21, thereby assisting the function of the auxiliary wheel 33 mentioned above.

[0134] (Mowing state by the first and second blades) As described above (state of mowing the ridge) and as shown in Figures 6, 7 and 8, when the first housing 21 travels over the upper surface E1 of the ridge, the first cutting blade 11 is driven to rotate in the rotation direction B1, causing the first cutting blade 11 to cut grass near the front of the first housing 21, and the cut grass moves rearward along the axis P3 as the first cutting blade 11 rotates, and mainly comes out rearward through the opening 78.

[0135] The grass clippings may move from the fixed vertical side member 25 along the rear portion 24b and front portion 24a of the vertical surface portion 24 together with the first cutting blade 11, without coming out rearward through the opening 78. In this case, as described above (Configuration of the first housing) and as shown in Fig. 8, the rear portion 24b of the vertical surface portion 24 is formed so as to follow the rotation trajectory C1 of the outer periphery of the first cutting blade 11 in a plan view, so that the grass clippings rarely remain near the rear portion 24b of the vertical surface portion 24.

[0136] As described above (state of mowing ridge) and as shown in Figures 6, 7, and 8, when the second housing 22 travels along the slope E2 of the ridge, the second cutting blade 12 is rotationally driven in the rotation direction B2, causing the second cutting blade 12 to cut grass near the front of the second housing 22, and the cut grass moves rearward along the axis P3 as the second cutting blade 12 rotates, and mainly comes out rearward through the opening 78. Little grass comes out rearward between the rear surface 29b of the second housing 22 (vertical surface portion 29) and the slope E2 of the ridge, or between the vertical side member 30 and the slope E2 of the ridge.

[0137] The grass clippings may move together with the second cutting blade 12 from the rear surface 29b of the vertical surface portion 29 along the middle portion 29c and the horizontal surface portion 29a of the vertical surface portion 29, without coming out rearward through the opening 78. In this case, as described above (Configuration of the second housing) and as shown in Fig. 8, the middle portion 29c of the vertical surface portion 29 is formed in an arc shape so as to follow the rotation locus C2 of the outer periphery of the second cutting blade 12 in a plan view, and therefore the grass clippings rarely remain near the middle portion 29c of the vertical surface portion 29.

[0138] When the first cutting blade 11 and the second cutting blade 12 are driven to rotate, the upstream edges of the first extension portion 60a and the second extension portion 60b of the base 60 kick away pebbles and the like from the upper surface portion E1 and the slope portion E2 of the ridge.

[0139] As shown in Figures 8 and 11, in the first cutting blade 11 and the second cutting blade 12, the upstream edge portions of the first extension portion 60a and the second extension portion 60b of the base 60 are formed into an inclined surface 60c that is diagonally downward with respect to the rotation directions B1 and B2. Therefore, pebbles and the like are not bounced in a direction along the rotation directions B1 and B2 of the base 60, but are bounced diagonally downward with respect to the rotation directions B1 and B2 of the base 60, and hit the upper surface portion E1 and the slope portion E2 of the ridge.

[0140] This reduces the possibility that pebbles or the like will fly out from the first housing 21 and the second housing 22. Even if pebbles or the like fly out from the first housing 21 and the second housing 22, the force with which the pebbles or the like fly out is significantly reduced.

[0141] As described above (Configuration for supporting the first cutting blade and the second cutting blade), even if the first cutting blade 11 and the second cutting blade 12 are attached upside down to the bottom of the drive shafts 41, 42, the upstream edge and the downstream edge in the rotation directions B1, B2 of the first extension portion 60a of the base 60 will be interchanged, and the upstream edge and the downstream edge in the rotation directions B1, B2 of the second extension portion 60b of the base 60 will be interchanged.

[0142] As a result, the upstream edges of the first extending portion 60a and the second extending portion 60b of the base 60 in the rotation directions B1 and B2 become inclined surfaces 60d that face diagonally downward, resulting in the same situation as described above.

[0143] (Discharge state of grass clippings cut by the first and second cutting blades from the opening) As described above (cutting state by the first and second cutting blades) and as shown in Figures 2 and 17, the grass clippings emerge rearward from the opening 78, forming a continuous streak-like (mountain-like) mass. The streak-like (mountain-like) mass of grass clippings is formed near the junction between the top surface E1 of the ridge and the slope E2, and near the top of the slope E2 of the ridge (see state G1).

[0144] As described above (configuration relating to the opening for discharging grass clippings cut by the first cutting blade and the second cutting blade) and as shown in Figures 2 and 6, the vertical side portion 25a of the fixed vertical side member 25 is arranged at an angle when viewed from behind, and the vertical side portion 30a of the vertical side member 30 is arranged at an angle when viewed from behind, which makes it easy for streaky (mountain-shaped) clumps of cut grass to be formed into a trapezoidal cross section.

[0145] Because the extension portion 25b of the fixed vertical side member 25 extends diagonally from the vertical side portion 25a of the fixed vertical side member 25 toward the rear and the left-right center of the opening 78, and because the extension portion 30b of the vertical side member 30 extends diagonally from the vertical side portion 30a of the vertical side member 30 toward the rear and the left-right center of the opening 78, the lateral portions of the streaky (mountain-like) mass of cut grass are compressed by the extension portion 25b of the fixed vertical side member 25 and the extension portion 30b of the vertical side member 30.

[0146] The pressing member 80 is disposed behind the opening 78 and extends diagonally downward toward the rear, so that the upper portion of the streaky (mountain-shaped) clump of grass clippings is compacted by the pressing member 80.

[0147] The opening area of ​​the opening 78 can be increased or decreased by changing the position of the vertical side member 30 to the left or right depending on the amount of grass on the ridge and the condition of the grass (for example, whether it is wet after rain or dry, etc.). Since the opening 78 is located on the second housing 22 side relative to the rear wheel 2, the streaky (mountain-shaped) mass of grass clippings coming out of the opening 78 will not be crushed by the rear wheel 2.

[0148] This makes it difficult for the streaks (mountain range-shaped) masses of grass clippings to slide down the slope E2 of the ridge. Even if the streaks (mountain range-shaped) masses of grass clippings do slide down the slope E2 of the ridge, they tend to stop midway up the slope E2 of the ridge and are unlikely to slide down into the field.

[0149] (First Alternative Embodiment of the Invention) In the first cutting blade 11 and the second cutting blade 12, the upstream edge portion of the first extension portion 60a of the base 60 in the rotation directions B1 and B2 (hereinafter referred to as edge portion H11), the downstream edge portion of the first extension portion 60a of the base 60 in the rotation directions B1 and B2 (hereinafter referred to as edge portion H12), the upstream edge portion of the second extension portion 60b of the base 60 in the rotation directions B1 and B2 (hereinafter referred to as edge portion H21), and the downstream edge portion of the second extension portion 60b of the base 60 in the rotation directions B1 and B2 (hereinafter referred to as edge portion H22) can have various combinations of diagonally downward inclined surfaces and diagonally downward inclined surfaces as follows.

[0150] (1) The edge H11 is an inclined surface facing diagonally upward, the edge H12 is an inclined surface facing diagonally downward, the edge H21 is an inclined surface facing diagonally upward, and the edge H22 is an inclined surface facing diagonally downward. (2) The edge H11 is a diagonally downward inclined surface, the edge H12 is a diagonally downward inclined surface, the edge H21 is a diagonally upward inclined surface, and the edge H22 is a diagonally upward inclined surface.

[0151] (3) The edge H11 is an inclined surface facing diagonally upward, the edge H12 is an inclined surface facing diagonally upward, the edge H21 is an inclined surface facing diagonally downward, and the edge H22 is an inclined surface facing diagonally downward. (4) The edge H11 is a diagonally downward inclined surface, the edge H12 is a diagonally upward inclined surface, the edge H21 is a diagonally upward inclined surface, and the edge H22 is a diagonally downward inclined surface.

[0152] (5) The edge H11 is an inclined surface facing diagonally upward, the edge H12 is an inclined surface facing diagonally downward, the edge H21 is an inclined surface facing diagonally downward, and the edge H22 is an inclined surface facing diagonally upward. (6) All of the edges H11, H12, H21, and H22 are inclined surfaces that slope diagonally downward. (7) All of the edges H11, H12, H21, and H22 are inclined surfaces that face diagonally upward.

[0153] (Second Alternative Embodiment of the Invention) When the first cutting blade 11 and the second cutting blade 12 are not used upside down, only the upstream edge portions of the first extension portion 60a and the second extension portion 60b of the base 60 in the rotation directions B1 and B2 need to be formed into an inclined surface 60c that is diagonally upward or diagonally downward relative to the rotation directions B1 and B2.

[0154] In the above-described configuration, one of the upstream edge portions of the first extending portion 60a of the base 60 in the rotation directions B1 and B2 and the upstream edge portion of the second extending portion 60b of the base 60 in the rotation directions B1 and B2 may be a diagonally downward inclined surface 60c, and the other may be a diagonally upward inclined surface 60d.

[0155] When the first cutting blade 11 and the second cutting blade 12 are not used upside down, the cutting edges 61a and 62a only need to be formed on the upstream edges of the first cutting blade portion 61 and the second cutting blade portion 62 in the rotation directions B1 and B2.

[0156] (Third Alternative Embodiment of the Invention) In the first cutting blade 11 and the second cutting blade 12, rather than attaching the first cutting blade portion 61 and the second cutting blade portion 62 to the base portion 60 so that they can swing freely, the first cutting blade portion 61 may be formed at one end of a single plate material, and the second cutting blade portion 62 may be formed at the other end of the single plate material.

[0157] According to this configuration, the portion of a single plate between the first cutting blade portion 61 and the second cutting blade portion 62 becomes the base portion 60, and the first cutting blade portion 61 and the second cutting blade portion 62 are fixed to the base portion 60 without being able to swing freely.

[0158] (Fourth Alternative Embodiment of the Invention) In a cross-sectional view of the base 60, the inclined surfaces 60c and 60d may be formed in an arc shape instead of a straight line shape. [Industrial Applicability]

[0159] The present invention provides For walk-behind lawn mowers Applicable. [Explanation of symbols]

[0160] 1 front wheel 2 rear wheels 3 Engine 11 1st cutting blade 12 Second cutting blade 21 First Housing 22 Second Housing 24a Front part (side part) 24b Rear (connection part) 25. Fixed vertical section (rear face) 29a Transverse face 29b Rear face 29c Middle section (connection part) 33 Subsidized wheels 60 base 60a First extension 60b 2nd extension 61 1st cutting blade section 62 2nd cutting blade part A11 Straight Forward Posture A21 Straight Forward Posture A12 Tilting Posture A22 Tilting posture B1 Rotation direction B2 Rotation direction C1 rotation trajectory C2 rotation trajectory D1 Diameter D2 diameter P1 axis center (First upper and lower shaft cores) P2 axis center (Second upper and lower shaft cores) P3 Shaft Core (Front and Rear Shaft Cores) P11 Axial center (1st axis) P12 Axis core (2nd axis core) L11 length L12 length

Claims

1. A first cutting blade that is driven to rotate around a first vertical axis along the vertical direction, and a first housing that accommodates the first cutting blade; a second cutting blade that is driven to rotate about a second vertical axis along the vertical direction, and a second housing that houses the second cutting blade; the first housing and the second housing are arranged side by side along a left-right direction, and the second housing is supported by the first housing so as to be vertically positionally changeable about a front-rear axis along a front-rear direction, a rotation direction of the first cutting blade and the second cutting blade is set so that the first cutting blade and the second cutting blade move rearward at the position of the front-rear axis, A walk-behind mower in which the connection portion between the side surface portion of the first housing on the opposite side of the front-to-rear axis and the rear surface portion of the first housing is formed so as to follow the rotational trajectory of the outer periphery of the first cutting blade in a plan view.

2. A walk-behind brush cutter as described in Claim 1, wherein the connection portion between the side surface portion on the opposite side of the front-to-rear axis of the second housing and the rear surface portion of the second housing is formed so as to follow the rotational trajectory of the outer periphery of the second cutting blade in a plan view.

3. A walk-behind brush cutter as described in claim 1, wherein the diameter of the rotational trajectory of the outer periphery of the second cutting blade is larger than the diameter of the rotational trajectory of the outer periphery of the first cutting blade.

4. The first cutting blade and the second cutting blade are a base portion that is rotatably driven around the first vertical axis and the second vertical axis, and that has a first extending portion that extends in one direction from the first vertical axis and a second extending portion that extends in the other direction opposite to the first vertical axis; a first cutting blade unit attached to an end of the first extension unit so as to be freely swingable around a first axis along the up-down direction; a second cutting blade portion attached to the end of the second extension portion so as to be freely swingable around a second axis along the up-down direction, In the first cutting blade portion and the second cutting blade portion of the first cutting blade and the second cutting blade, a length from the first axis to an outer end of the first cutting blade portion is the same as a length from the second axis to an outer end of the second cutting blade portion, The walk-behind mower according to claim 3, wherein the length between the first axis and the second axis at the base of the second cutting blade is longer than the length between the first axis and the second axis at the base of the first cutting blade.

5. The first cutting blade and the second cutting blade are a base portion that is rotatably driven around the first vertical axis and the second vertical axis, and that has a first extending portion that extends in one direction from the first vertical axis and a second extending portion that extends in the other direction opposite to the first vertical axis; a first cutting blade unit attached to an end of the first extension unit so as to be freely swingable around a first axis along the up-down direction; a second cutting blade portion attached to the end of the second extension portion so as to be freely swingable around a second axis along the up-down direction, In the first cutting blade and the second cutting blade, the first extending portion and the second extending portion are configured to have a tapered shape in which a width becomes smaller toward an outer portion in a radial direction in a plan view, The walk-behind brush cutter according to claim 3, wherein the first cutting blade portion and the second cutting blade portion are configured to have a flared shape in plan view, with a width increasing toward the radially outer portions.

6. A walk-behind brush cutter as described in claim 3, wherein the width of the second housing in the left-right direction is greater than the width of the first housing in the left-right direction.

7. A front wheel provided in front of the first housing and supporting the first housing; a rear wheel provided behind the first housing and supporting the first housing; 2. The walk-behind brush mower according to claim 1, wherein the front wheels are capable of changing their positions between a straight-ahead position in which the front wheels rotate along the fore-and-aft direction and an inclined position in which the front wheels rotate along an imaginary direction extending diagonally forward from the first housing on the opposite side of the second housing in the fore-and-aft direction.

8. An engine is provided, 8. The walk-behind brush mower according to claim 7, wherein power from the engine is transmitted to the front and rear wheels, thereby driving the front and rear wheels to rotate.

9. An auxiliary wheel is provided in front of the second housing and supports the second housing; 8. The walk-behind brush mower according to claim 7, wherein the auxiliary wheels are capable of changing their positions between a straight-ahead position in which the front wheels rotate along the fore-and-aft direction and an inclined position in which the auxiliary wheels rotate along an imaginary direction extending diagonally forward from the second housing toward the first housing in the fore-and-aft direction.

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