CN115500146A

CN115500146A - Cutting knife assembly and mower

Info

Publication number: CN115500146A
Application number: CN202110696169.5A
Authority: CN
Inventors: 冯守川
Original assignee: Globe Jiangsu Co Ltd
Current assignee: Globe Jiangsu Co Ltd
Priority date: 2021-06-22
Filing date: 2021-06-22
Publication date: 2022-12-23

Abstract

The invention discloses a cutting knife assembly and a mower, wherein the mowing assembly comprises a knife holder, a first boss and a second boss are arranged on a blade assembly surface of the knife holder, the height of the first boss is a first height, and the height of the second boss is a second height; the first blade is provided with a first mounting hole matched with the first boss; the second blade is provided with a second mounting hole matched with the second boss; the first blade is mounted to the first boss, and the second blade is mounted to the second boss. According to the cutting knife assembly, the step-shaped blade positioning and mounting boss is arranged on the knife holder, so that the double blades can be assembled and replaced more conveniently.

Description

Cutting knife assembly and mower

Technical Field

The invention relates to the technical field of garden tools, in particular to a cutting knife assembly and a mower.

Background

With the continuous development of the electric tool technology, the lawn mower is also widely applied. The grass cutter is mainly applied to garden decoration pruning, grassland greening pruning, urban streets, greening scenic spots, field pruning and field weeding, and is particularly applied to grasslands, football fields and other grassland fields in parks.

Taking a mower as an example, in order to obtain better grass chopping performance, double-layer blades are arranged on the mower device, and the two blades are staggered at a certain angle, so that grass can be cut twice from high to low, the cut grass is finer, and the purpose of grass chopping is achieved.

However, the fixing mode of the double blades of the existing mower is complex, no fool-proof structure is provided, and the assembly of the blade positions is not unique, so that the cutting height of the whole mower can be changed during cutting.

Disclosure of Invention

The invention aims to provide a cutting knife assembly and a mower, and aims to solve the technical problems that in the prior art, two blades of the mower are complex in fixing mode and have no fool-proof structure.

To achieve the above and other related objects, the present invention provides a cutter assembly comprising:

the cutter comprises a cutter holder, wherein a first boss and a second boss are arranged on a blade assembly surface of the cutter holder, the height of the first boss is a first height, and the height of the second boss is a second height;

the first blade is provided with a first mounting hole matched with the first boss;

the second blade is provided with a second mounting hole matched with the second boss;

the first blade is mounted to the first boss, and the second blade is mounted to the second boss.

In an alternative embodiment of the invention, the first height is greater than the second height.

In an alternative embodiment of the invention, the first height is in the range of 5-8mm and the second height is in the range of 2-4mm.

In an alternative embodiment of the invention, the first blade is superposed on the second blade and the first blade and the second blade are arranged in a staggered manner.

In an alternative embodiment of the invention, the second boss is located between the first boss and the insert seat.

In an alternative embodiment of the invention, the projected contour of the first boss on the seat is located within the projected contour of the second boss on the seat.

In an optional embodiment of the present invention, the first boss and the second boss are located at a center position of the tool holder, and are coaxially disposed.

In an optional embodiment of the present invention, at least one second positioning boss is further disposed on the insert mounting surface of the insert seat, and the second positioning boss is located on a side edge of the second boss.

In an optional embodiment of the present invention, the second blade has a second positioning hole matching with the second positioning boss.

In an optional embodiment of the present invention, the number of the second positioning bosses is two, and the second positioning bosses are arranged in central symmetry with the center of the second boss.

In an optional embodiment of the present invention, the blade mounting surface of the blade holder is further provided with at least one first positioning boss, the first positioning boss is located on a side edge of the first boss, and the second positioning boss is located between the first positioning boss and the blade holder.

In an alternative embodiment of the invention, the first blade has a first locating hole matching the first locating boss.

In an optional embodiment of the present invention, the first positioning boss has a fool-proof design.

In an optional embodiment of the present invention, the first positioning boss is an arrow boss.

In an alternative embodiment of the invention, the arrow boss points towards the direction of rotation of the first blade.

In an optional embodiment of the present invention, two first positioning bosses are provided, and are arranged in central symmetry with a center of the first boss.

In an optional embodiment of the invention, a projected contour of the first positioning boss on the tool holder is located within a projected contour of the second positioning boss on the tool holder.

In an alternative embodiment of the present invention, at least one supporting boss is provided on an edge of the insert mounting surface of the insert holder, and the first insert is supported on a supporting table surface of the supporting boss.

In an optional embodiment of the invention, the number of the support bosses is two, and the support bosses are arranged in a central symmetry manner about the center of the tool apron.

In an alternative embodiment of the present invention, the holder has an output shaft mounting hole penetrating through the holder.

In an optional embodiment of the invention, a driven transmission structure is arranged in the output shaft mounting hole.

To achieve the above and other related objects, the present invention also provides a lawn mower comprising:

a body;

a drive assembly disposed on the body, the drive assembly having a rotary output shaft; and

a cutter assembly, the cutter assembly comprising:

According to the cutting knife assembly, the step-shaped blade positioning and mounting boss is arranged on the knife holder, so that the double blades can be assembled and replaced more conveniently.

The cutter assembly of the invention can avoid the reverse installation of the blade through the foolproof design on the cutter holder and the blade.

The cutter assembly has the advantages that the step-shaped blade positioning installation boss is arranged on the cutter holder, so that the effect of supporting the first blade can be realized when the first blade is independently assembled, and the position of the first blade can be kept unchanged.

Drawings

Fig. 1 is a schematic perspective view of a push mower according to the present invention.

Fig. 2 shows an exploded assembly view of the mowing assembly of the push mower of the present invention.

FIG. 3 is a bottom view of the first blade of the grass cutting assembly of the present invention.

Fig. 4 shows a front view of a first blade of the mowing assembly of the present invention.

Fig. 5 is a perspective view of a second blade of the grass cutting assembly of the present invention.

Fig. 6 shows a top view of a second blade of the mowing assembly of the present invention.

FIG. 7 shows a front view of a second blade of the grass cutting assembly of the present invention.

Fig. 8 is a perspective view of a blade holder of the grass cutting assembly of the present invention.

Fig. 9 is a bottom perspective view of a blade holder of the grass cutting assembly of the present invention.

Fig. 10 isbase:Sub>A sectional view taken alongbase:Sub>A-base:Sub>A in fig. 9.

FIG. 11 is a schematic view of the mower assembly of the present invention mounted on a rotatable output shaft.

Fig. 12 is a cross-sectional view taken along the line B-B in fig. 11.

A first blade 100; a first positioning hole 101; a first mounting hole 102; a first intermediate portion 103; a first cutting portion 104; a rotation direction indicator 105; a second blade 200; a second positioning hole 201; a second mounting hole 202; a second intermediate portion 203; a second cutting portion 204; a tool holder 300; a second positioning boss 301; a second boss 302; a support boss 303; a first positioning boss 304; a first boss 305; a support mesa 306; a tool holder body 307; a central boss 308; a driven transmission structure 309; a third bore section 310; a second bore section 311; a first bore section 312; a drive assembly 400; a rotating output shaft 410; a fastening bolt 500; an operating assembly 600; a control component 610; a grass collecting assembly 700; a walking assembly 800; a rear wheel 810; a front wheel 820; a housing 900.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

Please refer to fig. 1-12. It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

In this embodiment, a central pair is defined as one of the two components rotated 180 about a center and the other component coinciding.

As shown in fig. 1 and 2, the present embodiment provides a walk-behind mower including a housing 900, a cutter assembly, a driving assembly 400, a power supply assembly (not shown), a grass collecting assembly 700, a walking assembly 800, and an operating assembly 600.

As shown in fig. 1 and 2, a cutter assembly including a holder 300 and first and second blades 100 (grass collecting blades) and 200 (grass cutting blades) mounted on the holder 300 is accommodated in a housing 900, and a cutting space is formed in the housing 900. The driving assembly 400 is at least partially accommodated in the housing 900, provides power for the cutter assembly to drive the cutter assembly to rotate, and the driving assembly 400 is electrically connected with the control assembly to output different rotating speeds and provide different cutting speeds for the push mower. The power supply assembly provides power to the driving assembly 400, and may be an AC power source or a dc power source, such as a battery pack. The grass collecting assembly 700 communicates with the cutting space of the housing 900 through a grass collecting passage (not shown) for collecting weeds cut by the cutter assemblies, and the grass collecting assembly 700 may be, for example, a grass collecting bag or a grass collecting box. The walking assembly 800 is used for supporting the push mower to rotate relative to the ground, so that an operator can easily push the push mower to cut grass, and the walking assembly 800 comprises a pair of front wheels 820 and a pair of rear wheels 810. The operating assembly 600 is a push rod extending from the rear of the hand-push mower, a control assembly 610 is further arranged on the push rod, and an operator can control the hand-push mower through wired or wireless communication modes such as Bluetooth, WIFI, infrared and radio frequency control lines and the like. As shown in fig. 3 and 4, in the present embodiment, the first blade 100 includes a first intermediate portion 103 arranged in a flat plate shape and first cutting portions 104 respectively provided at both ends of the first intermediate portion 103, the first intermediate portion 103 may have, for example, an elongated rectangular shape for being attached to the holder 300, the first cutting portions 104 are disposed in a twisted manner with respect to the intermediate portion in the longitudinal direction of the first intermediate portion 103, one end of the first cutting portion 104 facing the blade rotation direction (the direction indicated by the rotation direction indicator 105) is provided with a first cutting edge for cutting grass blades and cutting the grass blades into chips, and one end of the first cutting portion 104 facing away from the first cutting edge is formed with a grass collecting slope for collecting grass facing the blade rotation direction.

As shown in fig. 3 and 4, in the present embodiment, the first blade 100 has a first mounting hole 102 penetrating through the first blade 100 and located at the center, and two sides of the first mounting hole 102 respectively have a first positioning hole 101 penetrating through the first blade 100. The first mounting hole 102 and the first positioning hole 101 are disposed along a longitudinal direction of the first blade 100 (as shown in fig. 3), but the first mounting hole 102 and the first positioning hole 101 may also be disposed along a direction forming an angle with the longitudinal direction of the first blade 100. The first positioning hole 101 may be, for example, a dart with a fool-proof function, and the two darts are oppositely directed, so that if the first blade 100 is reversed, the assembly is disabled, and the reverse installation can be avoided. The arrow holes point to the blade rotation direction of the first blade 100 in the circumferential direction, the two arrow holes are centrosymmetric about the center of the first mounting hole 102, and the tool holder 300 has two arrow bosses (see fig. 8 and 9) respectively matching with the two arrow holes on the first blade 100 to position the first blade 100. The arrowhead holes on both sides indicate opposite directions, but the same size, and the first blade 100 can satisfy the dynamic balance and static balance requirements in principle. It is noted that the arrow hole may also be designed not to be centrosymmetric.

As shown in fig. 3 and 4, in the present embodiment, a turning indicator 105 is provided on a bottom surface (i.e., a side surface away from the tool holder 300) of the first blade 100, and the turning indicator 105 includes two pieces, each of which is arranged in a central symmetry manner with respect to a center of the first mounting hole 102. It should be noted that the arrow hole may point towards the blade rotation direction of the first blade 100, and the arrow hole of the first blade 100 has a blade rotation direction indicating function, which merges the rotation direction indicating function, so that the rotation direction indicator 105 may not be disposed on the first blade 100.

As shown in fig. 5 to 7, in the present embodiment, in order to achieve a better cutting effect and to facilitate differentiation, the second blade 200 is different from the first blade 100 in shape and structure. The second blade 200 includes a second intermediate portion 203 arranged in a flat plate shape and second cutting portions 204 respectively provided at both ends of the second intermediate portion 203, the second intermediate portion 203 may be, for example, in an elongated rectangular shape for being mounted to the holder 300, the second cutting portions 204 are bent and provided at a side of the second intermediate portion 203 facing the holder 300, the second cutting portions 204 are bent toward a side close to the holder 300, an end of the second cutting portion 204 remote from the second intermediate portion 203 is arranged in parallel to the second intermediate portion 203, that is, the second cutting portion 204 is bent toward a side close to the holder 300, and an end of the second cutting portion 204 facing the blade rotation direction is provided with a second cutting edge for cutting the grass blades and cutting the grass blades into chips.

As shown in fig. 5-7, in the present embodiment, the second blade 200 has a second mounting hole 202 penetrating through the second blade 200 and located at the center, and two sides of the second mounting hole 202 respectively have a second positioning hole 201 penetrating through the second blade 200. The second mounting hole 202 and the second positioning hole 201 are arranged at an angle to the longitudinal direction of the second insert 200 (as shown in fig. 5 and 6), so that the second insert 200 and the first insert 100 are at the same angle when the second insert 200 and the first insert 100 are assembled to the holder 300. Of course, the second mounting hole 202 and the second positioning hole 201 may be arranged along the longitudinal direction of the second blade 200. In the present embodiment, the size of the second mounting hole 202 of the second blade 200 is larger than the size of the first mounting hole 102 of the first blade 100, and the size of the second positioning hole 201 of the second blade 200 is larger than the size of the first positioning hole 101 of the first blade 100.

As shown in fig. 8 to 10, in the present embodiment, the tool holder 300 includes a tool holder body 307 and a central boss 308 disposed at the center of the top surface of the tool holder body 307, and the diameter of the central boss 308 gradually decreases from the bottom end to the top end and then remains constant.

A first step boss and two second step bosses are provided on the bottom surface (blade mounting surface) of the tool holder body 307, the first step boss is provided at the center of the bottom surface of the tool holder body 307, and the two second step bosses are arranged in central symmetry with the center of the first step boss. It should be noted that, in some embodiments, only one second step protrusion may be disposed on the bottom surface of the tool holder body 307, and the second step protrusion is located on the side of the first step protrusion.

As shown in fig. 8 to 10, in the present embodiment, the first step boss includes a first boss 305 and a second boss 302 coaxially disposed on the bottom surface of the holder body 307, the first boss 305 matches with the first mounting hole 102, the second boss 302 matches with the second mounting hole 202, the second boss 302 is located between the first boss 305 and the holder body 307, the projection of the second boss 302 and the first boss 305 on the bottom surface of the holder body 307 is in a nested relationship, and the contour of the first boss 305 is located within the contour of the second boss 302. The height of the first bosses 305 is defined as a first height and the height of the second bosses 302 is defined as a second height, wherein the first height is greater than the second height. By way of example, the first height is in the range of 5-8mm, such as 5mm, 6mm, 7mm or 8mm, and the second height is in the range of 2-4mm, such as 2mm, 3mm, 4mm.

As shown in fig. 8 to 10, in the present embodiment, the second step boss includes a second positioning boss 301 and a first positioning boss 304, the second positioning boss 301 is coaxially disposed on the bottom surface of the tool holder body 307 and matches with the second positioning hole 201, the first positioning boss 304 matches with the first positioning hole 101, the second positioning boss 301 is located between the first positioning boss 304 and the tool holder body 307, the second positioning boss 301 and the first positioning boss 304 are in a nested relationship on the bottom surface of the tool holder body 307, and the contour of the first positioning boss 304 is located within the contour of the second positioning boss 301. The second positioning boss 301 and the second boss 302 serve as a second blade 200 mounting structure for mounting the second blade 200; the first positioning boss 304 and the first boss 305 serve as a first blade 100 mounting structure for mounting the first blade 100. As an example, the first positioning boss 304 may be an arrow boss or other suitable boss with fool-proof function, and two arrow bosses arranged in a central symmetry with respect to the center of the first boss 305 are more favorable for transmitting the torque of the rotating output shaft 410 to the blade. It should be noted that, the matching of any mounting hole and the corresponding positioning boss means that the height of the mounting hole and the corresponding positioning boss is the same, and the shapes of the mounting hole and the corresponding positioning boss are matched.

In an alternative embodiment, as shown in fig. 8-10, in order to provide a better support for the first insert 100, two support bosses 303 are provided on the edge of the insert mounting surface of the insert holder 300, the two support bosses 303 being arranged in a central symmetry with respect to the center of the insert holder 300. The support boss 303 has an L-shaped configuration, the support boss 303 has a support land 306 for supporting the first blade 100, and the height of the support land 306 is the same as the height of the second boss 302 and the second positioning boss 301, so that both ends of the first middle portion 103 of the first blade 100 can be supported on the support land 306 of the support boss 303 when the first blade 100 is assembled to the tool holder 300. It will be appreciated that in some embodiments, only one support boss 303 may be provided on the edge of the insert mounting surface of the tool holder 300.

As shown in fig. 8-10, in the present embodiment, a step-shaped output shaft mounting hole penetrating through the central boss 308 and the tool holder body 307 is provided at the center of the tool holder 300, and the output shaft mounting hole sequentially includes a first bore section 312, a second bore section 311, and a third bore section 310, which are coaxial and have sequentially decreasing diameters, from an end close to the rotation output shaft 410 to an end far from the rotation output shaft 410, the first bore section 312 and the second bore section 311 are used for the rotation output shaft 410 to pass through, the third bore section 310 is used for a fastening bolt 500 (fastener) to pass through, when the rotation output shaft 410 is fixedly connected to the tool holder 300, the free end of the rotation output shaft 410 sequentially passes through the first bore section 312 and the second bore section 311 from the top end of the output shaft mounting hole, and the fastening bolt 500 is screwed with the internal threaded hole at the free end of the rotation output shaft 410 after the third bore section 310 from the bottom end of the output shaft mounting hole, so as to assemble the cutter assembly on the rotation output shaft 410.

As shown in fig. 8-10, in the present embodiment, a driven transmission structure is disposed at the bottom of the second bore section 311 (an end close to the third bore section 310), a driving transmission structure (not shown) is disposed at the free end of the rotating output shaft 410, and when the fastening bolt 500 is inserted into the bottom of the second bore section 311, the driven transmission structure 309 in the second bore section 311 and the driving transmission structure of the rotating output shaft 410 form a transmission fit, so that the tool holder 300 drives the first blade 100 and the second blade 200 to rotate along with the rotation of the rotating output shaft 410, thereby performing a mowing operation. The driving transmission structure of the rotating output shaft 410 may be, for example, a notch disposed at the free end of the rotating output shaft 410, and the driven transmission structure is a protruding block 309 disposed at the bottom of the second bore section 311 and matching with the notch. It will be appreciated that in other embodiments, the driving and driven transmission structures may be any structure capable of achieving a driving engagement, such as driving and driven ratchet teeth that are driving engaged, driving and driven teeth that are driving engaged, or protrusions that protrude in opposite directions that are driving engaged, etc.

As shown in fig. 11 and 12, when the mowing assembly is assembled, the positioning and mounting holes (the second mounting hole 202 and the second positioning hole 201) on the second blade 200 are firstly assembled on the mounting structure of the second blade 200 after passing through the mounting structure of the first blade 100; the first blade 100 is then assembled to the first blade 100 mounting structure with the first blade 100 overlying the second blade 200 and being staggered relative to each other, i.e., the first blade 100 and the second blade 200 are disposed at an angle. The first blade 100 and the second blade 200 can cut the grass blades twice, the cutting edge of the first blade 100 is positioned in front of the cutting edge of the second blade 200, when cutting, the first blade 100 firstly cuts the grass blades, and then the second blade 200 cuts the grass blades again, so that a better grass chopping effect can be achieved.

When the first blade 100 is separately assembled, since the second blade 200 is positioned and installed to have a large size, it can play a role of supporting the first blade 100, and the position of the first blade 100 can be maintained. In addition, when the support boss 303 is provided on the tool holder 300, the support boss 303 can position the mounting structure with the second insert 200 while the first insert 100 performs a supporting function.

It should be noted that the mowing module of the present invention can be applied to a 3-wheel walk-behind mower, a riding mower, or an automatic mower, in addition to the 4-wheel walk-behind mower shown in fig. 1 and 2; the mower may be an electric or gasoline mower.

In conclusion, the cutting knife assembly provided by the invention has the advantages that the stepped blade positioning and mounting boss is arranged on the knife holder, so that the double blades can be assembled and replaced more conveniently. The cutter assembly can avoid the reverse installation of the blade through the foolproof design on the cutter holder and the blade. According to the cutting knife assembly, the step-shaped blade positioning and mounting boss is arranged on the knife holder, so that the effect of supporting the first blade can be achieved when the first blade is independently assembled, and the position of the first blade can be kept unchanged.

In the description herein, numerous specific details are provided, such as examples of components and/or methods, to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of embodiments of the invention.

It will also be appreciated that one or more of the elements shown in the figures can also be implemented in a more separated or integrated manner, or even removed for inoperability in some circumstances or provided for usefulness in accordance with a particular application.

Additionally, any labeled arrows in the drawings/figures should be considered only as exemplary, and not limiting, unless otherwise specifically noted. Further, as used herein, the term "or" is generally intended to mean "and/or" unless otherwise indicated. Combinations of components or steps will also be considered as being noted where terminology is foreseen as rendering the ability to separate or combine is unclear.

The above description of illustrated embodiments of the invention, including what is described in the abstract of the specification, is not intended to be exhaustive or to limit the invention to the precise forms disclosed herein. While specific embodiments of, and examples for, the invention are described herein for illustrative purposes only, various equivalent modifications are possible within the spirit and scope of the present invention, as those skilled in the relevant art will recognize and appreciate. As indicated, these modifications may be made to the present invention in light of the foregoing description of illustrated embodiments of the present invention and are to be included within the spirit and scope of the present invention.

The systems and methods have been described herein in general terms as the details aid in understanding the invention. Furthermore, various specific details have been given to provide a general understanding of the embodiments of the invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced without one or more of the specific details, or with other apparatus, systems, assemblies, methods, components, materials, parts, and/or the like. In other instances, well-known structures, materials, and/or operations are not specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

Thus, while the present invention has been described herein with reference to particular embodiments thereof, a latitude of modification, various changes and substitutions are intended in the foregoing disclosures, and it will be appreciated that in some instances some features of the invention will be employed without a corresponding use of other features without departing from the scope and spirit of the invention as set forth. Thus, many modifications may be made to adapt a particular situation or material to the essential scope and spirit of the present invention. It is intended that the invention not be limited to the particular terms used in following claims and/or to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include any and all embodiments and equivalents falling within the scope of the appended claims. Accordingly, the scope of the invention is to be determined solely by the appended claims.

Claims

1. A cutter assembly for a lawn mower, comprising:

the cutter comprises a cutter holder, wherein a first boss and a second boss are arranged on a blade assembling surface of the cutter holder, the height of the first boss is a first height, and the height of the second boss is a second height;

2. The cutter assembly of claim 1, wherein the first height is greater than the second height.

3. The cutter assembly of claim 2, wherein the first height is in the range of 5-8mm and the second height is in the range of 2-4mm.

4. The cutter assembly of claim 1 wherein the first blade overlies the second blade and the blades are offset from one another.

5. The cutter assembly of claim 1, wherein the second boss is located between the first boss and the seat.

6. The cutting knife assembly as recited in claim 5, wherein a projected profile of the first boss on the knife seat is located within a projected profile of the second boss on the knife seat.

7. The cutter assembly of claim 5 wherein the first boss and the second boss are located in a central position of the holder and are coaxially disposed.

8. The cutter assembly as recited in claim 1 wherein said blade mounting surface of said blade holder is further provided with at least one second locating projection, said second locating projection being located laterally of said second projection.

9. The cutting knife assembly as set forth in claim 8, wherein said second blade has a second locating hole that mates with said second locating boss.

10. The cutting knife assembly of claim 8, wherein there are two of the second locating bosses, arranged in central symmetry about the center of the second boss.

11. The cutter assembly as recited in claim 8 wherein said blade mounting surface of said blade holder is further provided with at least a first locating projection, said first locating projection being located laterally of said first projection, said second locating projection being located between said first locating projection and said blade holder.

12. The cutter assembly of claim 11 wherein the first blade has a first locator hole that mates with the first locator boss.

13. The cutting knife assembly of claim 11, wherein the first locating boss is of a fool-proof design.

14. The cutter assembly of claim 13, wherein the first positioning boss is an arrow boss.

15. The cutter assembly of claim 14, wherein the arrow boss points in a direction toward the direction of rotation of the first blade.

16. The cutter assembly of claim 11, wherein there are two first locating bosses arranged in a central symmetry about a center of the first boss.

17. The cutter assembly of claim 11, wherein a projected contour of the first locating boss on the seat is within a projected contour of the second locating boss on the seat.

18. The cutter assembly as recited in claim 1 wherein the edge of the blade mounting surface of said blade holder is provided with at least one support ledge, said first blade being supported on a support land of said support ledge.

19. The cutter assembly of claim 18, wherein there are two support bosses arranged in a central symmetrical arrangement about a center of the seat.

20. A lawn mower, comprising:

a body;

a cutter assembly, the cutter assembly comprising: