Lawn mower

Abstract

To provide a technology to suppress noise of a lawn mower.SOLUTION: A lawn mower includes: a deck having a mowing blade for mowing lawn, an upper wall visually recognized when the lawn mower is viewed from below, a surrounding wall extending downward from the upper wall for defining a lower side opening opposed to the ground when the lawn mower is placed on the ground, and an inside space defined by the upper wall and the surrounding wall for storing the mowing blade; and an inside protrusion attached to the surrounding wall so as to protrude from the surrounding wall toward the inside space below the mowing blade, which is constituted separately from the surrounding wall.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a lawnmower. [Background technology]

[0002] Patent Document 1 discloses a lawnmower comprising a deck having a blade for cutting grass, an upper wall that is visible when the lawnmower is viewed from below, a surrounding wall extending downward from the upper wall and defining a lower opening that faces the ground when the lawnmower is placed on the ground, and an inner space defined by the upper wall and the surrounding wall for accommodating the blade. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2004-000127 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the lawnmower of Patent Document 1, when the cutting blade is driven, outside air is drawn into the inner space. A flow of air leaking from the inner space to the outside occurs near the inner wall of the surrounding wall. When air leaks from the inner space to the outside, noise is generated.

[0005] This specification provides a technique that can suppress lawnmower noise. [Means for solving the problem]

[0006] The lawnmower disclosed in this specification may comprise a deck having a blade for cutting grass, an upper wall visible when the lawnmower is viewed from below, a surrounding wall extending downward from the upper wall and defining a lower opening that faces the ground when the lawnmower is placed on the ground, and an inner space defined by the upper wall and the surrounding wall and accommodating the blade, and an inner protrusion attached to the surrounding wall so as to protrude from the surrounding wall toward the inner space below the blade, the inner protrusion being configured separately from the surrounding wall.

[0007] According to the above configuration, the surrounding wall is provided with an inner protrusion that protrudes from the surrounding wall toward the inner space. In this case, the inner protrusion blocks the flow of air leaking from the inner space to the outside. This makes it possible to reduce the amount of air leaking from the inner space to the outside. As a result, it is possible to reduce the noise of the lawnmower.

[0008] Another lawnmower disclosed in this specification may include a deck having a cutting blade for cutting grass, an upper wall visible when the lawnmower is viewed from below, a peripheral wall extending downward from the upper wall, an inner space defined by the upper wall and the peripheral wall, and an inner protrusion connected to the peripheral wall below the cutting blade and protruding from the entire circumference of the peripheral wall toward the inner space, the inner protrusion being integral with the peripheral wall.

[0009] According to the above configuration, the inner protrusion protrudes from the entire circumference of the peripheral wall toward the inner space. In this case, the inner protrusion obstructs the flow of air leaking from the inner space to the outside. This makes it possible to reduce the amount of air leaking from the inner space to the outside. As a result, it is possible to reduce the noise of the lawnmower. [Brief description of the drawings]

[0010] [Figure 1] 1 is a perspective view of a lawnmower 2 according to a first embodiment, as viewed from the upper right front. [Diagram 2]FIG. 1 is a perspective view of a lawnmower 2 according to a first embodiment, as viewed from the lower left front. [Diagram 3] 1 is a perspective view of a lower deck 26 according to a first embodiment, as viewed from the left, lower, and front. [Figure 4] 1 is a right cross-sectional view of a lawnmower 2 according to a first embodiment, as viewed from the right. [Diagram 5] FIG. 5 is an enlarged view of a portion V in FIG. [Figure 6] FIG. 11 is a perspective view of a lawnmower 102 according to a second embodiment, as viewed from the lower left front. [Figure 7] 11 is a right cross-sectional view of a lawnmower 102 according to a second embodiment, as viewed from the right. FIG. [Figure 8] FIG. 8 is an enlarged view of part VIII in FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Representative, non-limiting embodiments of the present invention are described in detail below with reference to the drawings. This detailed description is intended simply to provide those skilled in the art with details for implementing the preferred embodiments of the present invention, and is not intended to limit the scope of the present invention. Additionally, the additional features and inventions disclosed may be used separately or in conjunction with other features and inventions to provide further improved lawn mowers.

[0012] In addition, the combinations of features and steps disclosed in the following detailed description are not essential for implementing the present invention in the broadest sense, but are specifically described only to illustrate representative embodiments of the present invention. Furthermore, the various features of the following representative embodiments and the various features described in the claims do not have to be combined in the exact manner of the embodiments described herein or in the order listed in order to provide additional and useful embodiments of the present invention.

[0013] All features described in the specification and / or claims are intended to be disclosed individually and independently of one another as limitations to the specific features described in the original disclosure and claims, apart from the configuration of features described in the examples and / or claims. Furthermore, all numerical ranges and group or aggregate descriptions are intended to disclose intermediate configurations thereof as limitations to the specific features described in the original disclosure and claims.

[0014] In one or more embodiments, a lawnmower may include a deck having a blade for cutting grass, an upper wall visible when the lawnmower is viewed from below, a peripheral wall extending downward from the upper wall and defining a lower opening that faces the ground when the lawnmower is placed on the ground, and an inner space defined by the upper wall and the peripheral wall and accommodating the blade, and an inner protrusion attached to the peripheral wall so as to protrude from the peripheral wall toward the inner space below the blade, the inner protrusion being configured separately from the peripheral wall.

[0015] In one or more embodiments, the inner projection may project from the entire perimeter of the peripheral wall toward the inner space.

[0016] With the above-described configuration, it is possible to prevent wind from leaking out of the inner space around the entire periphery of the surrounding wall, thereby further reducing noise from the lawnmower.

[0017] In one or more embodiments, the upper surface of the inner protrusion may be flat.

[0018] If an upper surface of the inner protrusion is provided with an upper protrusion that protrudes upward from the upper surface, a downwardly recessed portion is defined by the surrounding wall, the inner protrusion, and the upper protrusion. In this case, grass cut by the cutting blade accumulates in the recessed portion. With the above configuration, since the upper surface of the inner protrusion is flat, it is possible to prevent grass cut by the cutting blade from accumulating on the upper surface of the inner protrusion.

[0019] In one or more embodiments, a lawnmower may include a deck having an upper wall visible when viewed from below the lawnmower, a peripheral wall extending downwardly from the upper wall, an inner space defined by the upper wall and the peripheral wall, and an inner protrusion connected to the peripheral wall below the cutting blade and protruding from an entire circumference of the peripheral wall toward the inner space, the inner protrusion being integral with the peripheral wall.

[0020] In one or more embodiments, the upper surface of the inner protrusion may be flat.

[0021] According to the above configuration, since the upper surface of the inner protrusion is flat, it is possible to prevent grass cut by the cutting blade from accumulating on the upper surface of the inner protrusion.

[0022] (First embodiment) As shown in FIG. 1, the lawnmower 2 includes a main body unit 4, a handle unit 6, and a grass collection unit 8. The main body unit 4 includes wheels 10 that come into contact with the ground on the front left side (see FIG. 2), front right side, rear left side, and rear right side. The grass collection unit 8 is detachably attached to the rear of the main body unit 4. The handle unit 6 is connected to the upper rear part of the main body unit 4. When a user stands behind the lawnmower 2 and grasps the upper part of the handle unit 6 with both hands and pushes it forward, the wheels 10 rotate and the main body unit 4 moves forward along the ground.

[0023] The main unit 4 includes a deck 20 and a cowl 22. The deck 20 and the cowl 22 are made of resin. The resin is, for example, a thermoplastic resin such as plastic. Specifically, it is PP. The deck 20 includes an upper deck 24 and a lower deck 26. The cowl 22 is attached to the upper center of the upper deck 24. The upper deck 24 is fixed to the lower deck 26 with screws.

[0024] As shown in FIG. 3, the lower deck 26 includes an upper wall 30 and a surrounding wall 32. The upper wall 30 is disposed at a position where a part of the upper wall 30 is visible when the lawnmower 2 is viewed from below, and a first opening 30A is provided in the upper wall 30. The surrounding wall 32 is composed of a first surrounding wall 34 extending downward from the upper wall 30, and a second surrounding wall 35 connected to the first surrounding wall 34. The first surrounding wall 34 has a substantially cylindrical shape. A second opening 34A is provided in a right rear portion of the first surrounding wall 34. The second surrounding wall 35 is disposed in the second opening 34A at the lower portion of the first surrounding wall 34. The second surrounding wall 35 has a shape corresponding to the cylindrical shape of the first surrounding wall 34. The surrounding wall 32 at the rear lower portion is provided with a recessed portion 32A recessed upward. The recessed portion 32A is formed across the first surrounding wall 34 and the second surrounding wall 35. 4, an inner space 36, which is the space inside the lower deck 26, is defined by the upper wall 30 and the peripheral wall 32. In addition, a third opening 38 that opens downward is defined by the peripheral wall 32. The third opening 38 has a circular shape.

[0025] As shown in FIG. 2, the lawnmower 2 further includes a mounting unit 40. The mounting unit 40 includes a height adjustment section 42 and four arcuate sections 44A-44D. The height adjustment section 42 and the arcuate sections 44A-44D are made of metal. The metal may be, for example, steel or SPCC. The height adjustment section 42 has a shape corresponding to the recessed section 32A of the surrounding wall 32. The height adjustment section 42 is fixed to the recessed section 32A by screws. As shown in FIG. 4, the vertical position of the lower end of the height adjustment section 42 is the same as the vertical position of the lower end of a portion of the surrounding wall 32 where the recessed section 32A is not formed.

[0026] As shown in FIG. 2, the arc portions 44A to 44D have a flat plate shape. The arc portions 44A to 44D have an arc shape. The upper surfaces of the arc portions 44A to 44D are flat (see FIG. 4). The arc portions 44A to 44D are disposed on the front left, front right, rear left, and rear right of the bottom surface of the surrounding wall 32, respectively. The arc portions 44A to 44D are fixed to the surrounding wall 32 by screws. Note that parts of the arc portions 44C and 44D are fixed to the surrounding wall 32 by screws via the height adjustment portion 42. The arc portions 44A to 44D form a ring shape. As shown in FIG. 5, the inner diameter of the arc portions 44A to 44D is smaller than the inner diameter of the surrounding wall 32. That is, the arc portions 44A to 44D protrude from the inner wall of the surrounding wall 32 toward the inner space 36. A fourth opening 46 is defined by the arc portions 44A to 44D. The fourth opening 46 has a circular shape. As shown in FIG. 4, the opening area of ​​the fourth opening 46 is smaller than the opening area of ​​the third opening 38. In this manner, the mounting unit 40 is attached to the surrounding wall 32 to form an opening (i.e., the fourth opening 46) having a smaller opening area than the third opening 38 defined by the surrounding wall 32.

[0027] The inner space 36 of the deck 20 accommodates a drive shaft 50, a cutting blade 52, and a blower fan 54. The drive shaft 50 is disposed along the vertical direction and passes through the first opening 30A of the lower deck 26 in the vertical direction. The cutting blade 52 is fixed to the lower end of the drive shaft 50 and extends from the drive shaft 50 in a direction perpendicular to the drive shaft 50 (horizontal direction in this embodiment). A fin 52B is provided on the cutting edge 52A of the cutting blade 52. As shown in FIG. 4, the fin 52B extends outward from the cutting edge 52A. The fin 52B is inclined so that the side away from the cutting edge 52A faces upward. The cutting edge 52A of the cutting blade 52 is disposed above the lower end of the surrounding wall 32 and the mounting unit 40. Particularly, in this embodiment, the entire cutting blade 52 is disposed above the lower end of the surrounding wall 32 and the mounting unit 40. As shown in FIG. 5, the distance L1 between the arcuate portions 44A-44D of the mounting unit 40 and the cutting edge 52A of the cutting blade 52 in the up-down direction may be, for example, 9 mm to 13 mm, and is 11 mm in the embodiment. The cutting edge 52A of the cutting blade 52 is disposed on the inside of the radially inner ends of the arcuate portions 44A and 44C. The distance L2 in the front-rear direction between the cutting edge 52A and the radially inner ends of the arcuate portions 44A and 44C may be, for example, 4 mm to 6 mm, and is 5 mm in the embodiment. As shown in FIG. 4, the blower fan 54 is fixed to the drive shaft 50 above the cutting blade 52. The blower fan 54 generates an air flow that cools the motor 60 described later. In a state in which the grass collection unit 8 is attached to the rear of the main unit 4 (see FIG. 1), the inner space 36 of the deck 20 communicates with the space inside the grass collection unit 8 through the second opening 34A (see FIG. 3) of the surrounding wall 32. When the drive shaft 50 rotates, the cutting blade 52 rotates and cuts the grass on the ground. When the cutting blade 52 rotates, the fins 52B of the cutting blade 52 also rotate. This causes an air flow from the fourth opening 46 toward the inner space 36. Therefore, the grass cut by the cutting blade 52 is sucked up by the air flow caused by the rotation of the fins 52B and sent to the grass collection unit 8.

[0028] The upper surface of the upper deck 24 is provided with a fifth opening 24A having a substantially circular shape. The cowl 22 has a skirt portion 22A that protrudes downward in a substantially cylindrical shape. The upper portion of the skirt portion 22A is disposed within the fifth opening 24A, and the lower portion of the skirt portion 22A is disposed within the first opening 30A. The cowl 22 houses a motor 60, a battery 62, and a control board 64. The motor 60 is, for example, a brushless motor. In a modified example, the motor 60 may be a brushed motor. The motor 60 rotates a drive shaft 50. The drive shaft 50 connects the cutting blade 52 and the blower fan 54 disposed in the inner space 36 of the deck 20 to the motor 60 disposed in the cowl 22. The battery 62 is detachably attached to the battery attachment portion 22B of the cowl 22. The battery 62 is, for example, a secondary battery such as a lithium ion battery. The cowl 22 is provided with an openable / closable battery cover 66 that covers the outside of the battery 62 attached to the battery attachment portion 22B. The control board 64 controls the operation of the motor 60 by controlling the power supplied from the battery 62 to the motor 60.

[0029] As shown in FIG. 1, the handle unit 6 is connected to the upper rear part of the deck 20 and includes a substantially U-shaped lower frame 70 extending rearward and upward, and an approximately U-shaped upper frame 72 connected to the upper rear part of the lower frame 70 and extending rearward and upward, and then bending forward and upward. The upper frame 72 includes a grip 74 to be held by a user, a switch lever 76 disposed forward of the grip 74, a right holding part 78 fixed to the upper frame 72 below and to the right of the grip 74, and a left holding part 80 fixed to the upper frame 72 below and to the left of the grip 74. The switch lever 76 is supported by the right holding part 78 and the left holding part 80 so as to be rotatable around a rotation axis extending in the left-right direction. The switch lever 76 is biased by a spring (not shown) in a direction away from the grip 74. While holding the grip 74, the user can pull and operate the switch lever 76 with the fingers of the hand holding the grip 74. When the switch lever 76 is pulled, the control board 64 (see FIG. 4) rotates the motor 60 (see FIG. 4). When the switch lever 76 is released, the control board 64 (see FIG. 4) stops the rotation of the motor 60 (see FIG. 3).

[0030] In one or more embodiments, as shown in FIG. 4 , the lawnmower 2 comprises a deck 20 having a blade 52 for cutting grass, an upper wall 30 that is visible when the lawnmower 2 is viewed from below, a surrounding wall 32 extending downward from the upper wall 30 and defining a third opening 38 (an example of a "lower opening") that faces the ground when the lawnmower 2 is placed on the ground, and an inner space 36 that is defined by the upper wall 30 and the surrounding wall 32 and accommodates the blade 52, and arc portions 44A-44D (an example of an "inner protrusion") attached to the surrounding wall 32 below the blade 52 so as to protrude from the surrounding wall 32 toward the inner space 36, the arc portions 44A-44D being configured separately from the surrounding wall 32.

[0031] As described above, when the switch lever 76 (see FIG. 1) is pulled by the user holding the grip 74 (see FIG. 1), the control board 64 rotates the motor 60. The motor 60 rotates (drives) the cutting blade 52. The cutting blade 52 is driven, and the outside air is sucked into the inner space 36. In the vicinity of the inner wall of the surrounding wall 32, an air flow leaking from the inner space 36 to the outside occurs. According to the above configuration, the surrounding wall 32 is provided with the arc portions 44A-44D that protrude from the surrounding wall 32 toward the inner space 36. In this case, the arc portions 44A-44D obstruct the air flow leaking from the inner space 36 to the outside. This makes it possible to suppress the amount of air leaking from the inner space 36 to the outside. This makes it possible to suppress noise from the lawnmower 2.

[0032] In addition, when the lower deck 26 having the upper wall 30 and the surrounding wall 32 is made of resin, it is difficult to form a part that protrudes from the lowermost surface of the surrounding wall 32 toward the inner space 36 side integrally with the surrounding wall 32. This is because if the protruding part is formed on the surrounding wall 32, it becomes impossible to perform mold splitting when molding the lower deck 26. According to the above configuration, the surrounding wall 32 and the arc parts 44A to 44D are configured separately, so even if the surrounding wall 32 is made of resin, it is possible to easily form a part that protrudes from the surrounding wall 32 toward the inner space 36 by attaching the arc parts 44A to 44D to the surrounding wall 32. In addition, since the surrounding wall 32 and the arc parts 44A to 44D are separate, it is possible to easily change the shape, size, etc. of the part that protrudes from the surrounding wall 32 toward the inner space 36 by changing the shape and size of the arc parts 44A to 44D.

[0033] In one or more embodiments, as shown in FIG. 2, the arcuate portions 44A-44D protrude from the entire periphery of the peripheral wall 32 toward the interior space .

[0034] The above-described configuration can prevent wind from leaking out of the inner space 36 around the entire periphery of the surrounding wall 32. Therefore, noise from the lawnmower 2 can be further suppressed.

[0035] In one or more embodiments, as shown in FIG. 5, the upper surfaces of the arcuate portions 44A-44D are flat.

[0036] According to the above configuration, since the upper surfaces of the arcuate portions 44A to 44D are flat, grass cut by the cutting blade 52 can be prevented from accumulating on the upper surfaces of the arcuate portions 44A to 44D.

[0037] (Second Example) A lawnmower 102 of the second embodiment will be described with reference to Figures 6 to 8. The lawnmower 102 of the second embodiment has a deck 120 with a different configuration from the deck 20 of the lawnmower 2 of the first embodiment. Components common to the embodiments are given the same reference numerals and descriptions thereof will be omitted.

[0038] As shown in FIG. 6, the deck 120 includes an upper deck 24 and a lower deck 126. The deck 120 of this embodiment is made of metal. The metal is, for example, steel or aluminum. The lower deck 126 includes an upper wall 130, a peripheral wall 132, and a bottom wall 134. The upper wall 130, the peripheral wall 132, and the bottom wall 134 are integrally formed. The upper wall 130 is disposed at a position where a part of the upper wall 130 is visible when the lawnmower 102 is viewed from below. As shown in FIG. 7, the upper wall 130 is provided with a first opening 130A. The peripheral wall 132 extends downward from the upper wall 130. In this embodiment, the lower portion of the peripheral wall 132 has a substantially cylindrical shape. The upper wall 130 and the peripheral wall 132 define an inner space 136, which is a space inside the lower deck 126. The bottom wall 134 protrudes from the lower end of the surrounding wall 132 toward the inner space 136. The upper surface of the bottom wall 134 is flat. As shown in FIG. 8, the bottom wall 134 is located below the cutting edge 52A of the cutting blade 52. In the up-down direction, a distance L11 between the bottom wall 134 and the cutting edge 52A of the cutting blade 52 may be, for example, 9 mm to 13 mm, and is 11 mm in the embodiment. As shown in FIG. 6, the bottom wall 134 is provided over the entire circumferential direction. The bottom wall 134 has an annular shape. As shown in FIG. 8, the cutting edge 52A of the cutting blade 52 is disposed on the inside of the radially inner end of the bottom wall 134. A distance L12 in the front-rear direction between the cutting edge 52A and the radially inner end of the bottom wall 134 may be, for example, 4 mm to 6 mm, and is 5 mm in the embodiment. The bottom wall 134 defines a sixth opening 146 that opens downward. The sixth opening 146 has a circular shape.

[0039] In one or more embodiments, as shown in FIG. 7 , the lawnmower 102 includes a deck 120 having a cutting blade 52 for cutting grass, an upper wall 130 that is visible when the lawnmower 102 is viewed from below, a peripheral wall 132 extending downward from the upper wall 130, an inner space 136 defined by the upper wall 130 and the peripheral wall 132, and a bottom wall 134 (an example of an "inner protrusion") that is connected to the peripheral wall 132 below the cutting blade 52 and protrudes from the entire circumference of the peripheral wall 132 toward the inner space 136, and is integrally formed with the peripheral wall 132.

[0040] According to the above configuration, the bottom wall 134 protrudes from the entire periphery of the surrounding wall 132 toward the inner space 136. In this case, the bottom wall 134 blocks the flow of air leaking from the inner space 136 to the outside. This makes it possible to reduce the amount of air leaking from the inner space 136 to the outside. As a result, the noise of the lawnmower 102 can be reduced.

[0041] In one or more embodiments, as shown in FIG. 6, the upper surface of the bottom wall 134 is flat.

[0042] According to the above configuration, since the upper surface of the bottom wall 134 is flat, grass cut by the cutting blade 52 can be prevented from accumulating on the upper surface of the bottom wall 134.

[0043] (First Modification) In the first embodiment, the arc portions 44A-44D may be attached to 80% or more of the entire circumference of the peripheral wall 32. When the arc portions are attached to 80% or more of the entire circumference of the peripheral wall 32, it is preferable that the arc portions have a continuous shape.

[0044] (Second Modification) The mounting unit 40 may be made of resin.

[0045] (Third Modification) In the first embodiment, the height adjustment portion 42 and the four arcuate portions 44A to 44D may be formed integrally.

[0046] (Fourth Modification) In the first embodiment, the arcuate portions 44A to 44D may be disposed above the lowermost surface of the peripheral wall 32. In other words, it is only necessary that the arcuate portions 44A to 44D are disposed below the cutting edge 52A of the cutting blade 52.

[0047] (Fifth Modification) In the first embodiment, an upward protrusion protruding upward from the upper surface of each of the arcuate portions 44A to 44D may be provided. In the second embodiment, an upward protrusion protruding upward from the upper surface of the bottom wall 134 may be provided.

[0048] (Sixth Modification) In the first embodiment, the deck 20 may be made of metal. [Explanation of symbols]

[0049] 2: Lawnmower 4: Main unit 6: Handle unit 8: Grass collection unit 10: Wheels 20: Deck 22: Cowl 22A: Skirt section 22B: Battery mounting section 24: Upper deck 24A: 5th opening 26: Lower deck 30: Upper wall 30A: 1st opening 32: Surrounding wall 32A: Recessed part 34: First surrounding wall 34A: 2nd opening 35: Second surrounding wall 36: Inner space 38: Third opening 40: Mounting unit 42: Height adjustment part 44A-44D: Arc section 46: 4th opening 50: Drive shaft 52:Kariblade 52A: Cutting edge 52B: Fin 54: Blower fan 60: Motor 62: Battery 64: Control board 66: Battery cover 70: Lower frame 72: Upper frame 74: Grip 76: Switch lever 78: Right side holding part 80:Left side holding part 102: Lawnmower 126: Lower Deck 130: Upper wall 130A: 1st opening 132: Surrounding wall 134: Bottom wall 136: Inner Space 146: 6th opening

Claims

1. A lawnmower comprising: A blade for cutting grass, a deck having an upper wall visible when the lawnmower is viewed from below, a peripheral wall extending downward from the upper wall and defining a lower opening facing the ground when the lawnmower is placed on the ground, and an inner space defined by the upper wall and the peripheral wall and accommodating the cutting blade; an inner protrusion attached to the peripheral wall below the cutting blade so as to protrude from the peripheral wall toward the inner space, the inner protrusion being configured separately from the peripheral wall; Lawn mower.

2. The lawnmower according to claim 1 , wherein the inner protrusion protrudes from an entire periphery of the peripheral wall toward the inner space.

3. The lawn mower according to claim 1 or 2, wherein an upper surface of the inner protrusion is flat.

4. A lawnmower comprising: A blade for cutting grass, the deck having an upper wall visible when the lawnmower is viewed from below, a peripheral wall extending downward from the upper wall, an inner space defined by the upper wall and the peripheral wall, and an inner protrusion connected to the peripheral wall below the cutting blade and protruding from the entire periphery of the peripheral wall toward the inner space, the inner protrusion being integrally formed with the peripheral wall, Lawn mower.

5. The lawn mower of claim 4 , wherein an upper surface of the inner projection is flat.

Images