GB2369765A

GB2369765A - Blade assembly

Info

Publication number: GB2369765A
Application number: GB0126733A
Authority: GB
Inventors: David Paul Seidel
Original assignee: Sunbeam Corp Ltd; Sunbeam Corp
Current assignee: Sunbeam Corp Ltd; Sunbeam Corp
Priority date: 2000-11-07
Filing date: 2001-11-07
Publication date: 2002-06-12
Also published as: AUPR126800A0; GB0126733D0

Abstract

A blade assembly to be attached to a rotatably driven disc 10 of a lawn mower. The assembly includes a blade member 13 pivotally mounted on the disc 10 by means of a mounting 11 The mounting 14 permits angular displacement of the blade member 13 about an axis extending generally radially with respect to the rotational axis of the disc 10. As resistance is encountered the blade member 13 becomes inclined. Accordingly, when little or no resistance is encountered, the blade member 13 is generally horizontally oriented and presents a minimum profile in respect of the air within which it is passing. This reduces noise and dust. In another embodiment, a flange (47, figure 7) may be included on the blade member. A fan member may also be included on the blade (figure 18).

Description

BLADE ASSEMBLY Technical Field The present invention relates to lawn mowers and more particularly to blade members for lawn mowers.

Background of the Invention A popular form of lawn mower includes a wheeled base upon which there is mounted a motor. The motor drives a disc located beneath the base. Attached to the disc are cutting blades which engage the grass as the disc is rotated. The grass clippings are then propelled through a chute in the base to be collected in a catcher. A handle extends upwardly from the base and is gripped by a user to propel the lawn mower. Mulching mower circulates the cutting rather than deliver them to a catcher.

The above mentioned lawn mower has a number of disadvantages including dust and noise creation.

Object of the Invention It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.

Summary of the Invention There is firstly disclosed herein a lawn mower blade member to be mounted on a rotatably driven support so as to be rotatably moved thereby about a generally upright axis, said blade member including: a mounting portion to engage the support so as to be secured thereto; a blade portion fixed to the mounting portion so as to be moved therewith, the blade portion having a longitudinal axis to have a major direction of extension radially relative to said upright axis, and wherein, the blade portion in use is angularly moveable about a pivot axis extending substantially parallel to said longitudinal axis so that the blade portion is adjustable in inclination relative to air through which the blade portion is to be moved.

Preferably the blade portion is angularly moveable between a position at which the blade portion is positioned in a plane substantially perpendicular to said upright axis, and an inclined position at which the blade portion is located in a plane inclined to said upright axis by an angle of 30 to 60 degrees.

Preferably said angle is about 45 degrees, Preferably the blade portion is adapted to cut grass- There is further disclosed herein a lawn mower blade member including : a mounting portion to be secured to a rotatably driven support so that the blade member rotates about a generally upright axis ; and a blade portion having a longitudinal length and transverse width and a radially outer upwardly extending flange extending substantially the width of the blade portion.

Preferably the blade portion is of a"U"configuration so as to provide said radially outer flange as well as a radially inner flange space from the outer flange by means of a transverse portion.

Brief Description of the Drawings A preferred form of the present invention will now be described by way of example with reference to the accompanying drawings wherein: Figure 1 is a schematic plan view of a portion of a lawn mower disc and blade member; Figure 2 is a schematic section side elevation of the blade portion and disc member of Figure 1; Figure 3 is a schematic end elevation of the disc portion and blade member of Figure 1 ; Figure 4 is a schematic plan view of the blade member of Figure 1; Figure 5 is a schematic side elevation of the blade member of Figure 1 ; Figure 6 is a schematic perspective view of a lawn mower disc and blade members ; Figure 7 is a schematic side view of the disc and blade members of Figure 6; Figure 8 is a schematic plan view of a portion of a further lawn mower disc and a blade member ; Figure 9 is a schematic section side elevation of the disc portion and blade member of Figure 8; Figure 10 is a schematic end elevation of the disc portion and blade member of Figure 8; Figure 11 is a schematic plan view of a portion of a lawn mower disc and blade member ; Figure 12 is a schematic end elevation of the disc portion and blade member of

Figure 11 ; Figure 13 is a schematic section side elevation of the disc portion and blade member of Figure 11 ;

Figure 14 is a schematic perspective view of a lawn mower disc and blade members; Figure 15 is a schematic view ouf porion of the disc and one of the blade members of Figure 14; Figure 16 is a schematic section plan view of a portion of a lawn mower disc and blade member; Figure 17 is a schematic sectioned side elevation of a portion of a lawn mower disc and blade member; Figure 18 is a schematic side elevation of the blade member of Figure 17 ; Figure 19 is a schematic plan view of the blade member of Figure 17; and Figure 20 is a schematic end elevation of the blade member of Figure 17.

Detailed Description of the Preferred Embodiments The following preferred embodiments relate to lawn mowers including a base upon which there is mounted a motor. The motor rotatably drives a cutting disc about a generally upright axis. The disc is located below the base and will have secured to it a plurality of blade members.

In Figures 1 to 5 of the accompanying drawings there is schematically depicted a portion of a disc 10 of a lawn mower. The disc 10 would typically include a central aperture 11 via which the disc 10 is attached to a shaft driven by the motor. The disc 10 would be rotated about a generally upright axis 15 to perform a grass cutting function. In Figure 1 the upper surface 12 of the disc 10 has secured to it a blade assembly including a blade member 13 secured to the disc 10 by means of a mounting 14. Accordingly the

blade member 13 is supported by the disc 10 and rotates therewith about the upright axis 15.

The mounting 14 includes a housing 16 which pivotally supports the blade member 13 for pivoting movement about an axis 17 which extends substantially normal to the axis 15. However in this respect it should be appreciated that the axis 19 may have some inclination relative to the axis 15 both vertically and horizontally.

The housing 16 is secured to the upper surface 12 by means of a clamp plate 17 bolted to the disc 10 by means of threaded fasteners 18.

Located within the housing 16 are bushes 19 and 20, and a bearing 22-The bush 20 is secured to the blade member 13 by means of a transverse pin 21.

Located between the bush 19 and housing 16 is a spring 23 which urges the bush 19 radially outwardly-Located between the bush 19 and the bush 20 is a further spring

24 which urges the bush 20 radially outwardly. The bushes 19 and 20 and bearing 22 provide for angular movement of the blade member 13 about the axis 17.

The bearing 22 and the associated bushes 19 and 20 are retained within the housing 16 by means of a flange 25 of the clamp plate 17 and the peripheral flange 26 of the disc 10.

The blade member 13 includes a mounting portion, in the form of a shaft 27, (providing the axis 17) and a blade portion 28. The shaft 27 has a passage 29 through which the pin 21 passes The blade portion 28 is of a"U"configuration so as to have a radially inner flange 29 joined to a radially outer flange 30 by means of a transverse portion 31. Clippings engaged by the blade portion 28 are propelled angularly and therefore have radial forces applied to them. The flange 30 aids in retaining the clippings to ensure that they are moved angularly about the axis 15 The flanges 29 and 30 are upwardly extending from the portion 31.

The spring 24 has one end attached to the bush 20 and the other end attached to the bush 19. The bush 19 is angularly moveable about the axis 17 relative to the bush 20. The spring 23 has one end attached to the bush 19 and the other end attached to the housing 16. Both springs 23 and 24 are helical springs.

The blade portion 28 is attached to the shaft 27 by means of a bolt 32 and a

cooperating nut 33. Typically the bolt 32 and nut 33 would permit angular movement of the blade portion 28 about the longitudinal axis of the bolt 32 so that the blade portion 28 pivots when engaged by an obstacle. Centrifugal force would return the blade portion 28 to a generally radial orientation.

In operation of the above described blade member 13, the blade portion 28 is oriented in the position illustrated when at rest. When the disc 10 is angularly driven about the axis 15 the blade portion 28 will remain in the position depicted (that is with the base portion 31 oriented generally horizontally) until the blade portion 28 encounters resistance. Resistance would be in the form of engaging grass and cutting the grass to produce grass clippings. When the resistance is low the blade portion 28 will be in the position substantially as illustrated. However as the resistance increases the force applied to the blade portion 28 will cause the blade portion 28 to pivot about the axis 17. This pivoting movement will cause tensioning of the springs 23 and 24. The tension produced by the springs 23 and 24 will balance the forces applied to the blade portion 28 and

maintain the blade portion 28 at an inclined position relative to the air through which the blade portion 28 is passing.

The spring 23 has a higher spring rate than the spring 24. Accordingly the spring 24 will deform first until the resistance encountered by the blade portion 28 exceeds a predetermined value at which the spring 23 will begin to deform. More particularly the spring 23 is provided to enable pivoting of the blade portion 28 about the axis 17 should a solid object be encountered.

The above described preferred embodiment has the advantage of maintaining the blade portion 28 oriented as illustrated so that there is minimal air disturbance. This reduces noise and dust creation. The blade portion 28 is only inclined to any substantial degree when resistance is encountered, that when grass is to be cut. As can be seen in Figure 3, the blade portion 28 is angularly moveable between the two positions illustrated.

Preferably the blade portion 28 would be angularly moveable between a position at which the portion 31 is located in a plane which is substantially perpendicular to the axis 15 and therefore parallel to the axis 17, and a second position at which the blade portion 31 is located in a plane intersecting the axis 15 at about 45 degrees-That is if the lawn mower is located on a horizontal surface the blade portion 31 would be moveable between a horizontal position and a position inclined at 45 degrees to the horizontal. In operation of the above described embodiment the blade member 28 cuts the grass as well as produces air currents which cause the blade cuttings to circulate and if required to be delivered to a chute from where the grass cuttings are delivered to a catcher.

In the embodiment of Figures 6 and 7 the functions performed by the above mentioned blade portion 28 are separated. More particularly in this embodiment there is provided a"fan"blade member 40 and a cutting blade member 41.

In Figures 6 and 7 there is schematically depicted a lawn mower disc 42 which would be driven via a central aperture by a motor and associated shaft connected to the disc 42 Mounted on the disc 42 is a blade assembly including a housing 43 which supports the blade members 40. Also attached to the housing 43 are the blade members 41.

The blade members 41 are attached to the housing 43 by means of a nut and bolt 44 so that should the blade member 41 encounter an obstacle the blade member 41 can pivot. After pivoting each blade member 41 would then return to a generally radial orientation under the influence of a centrifugal force.

The blade members 40 include a blade portion 45 of"U"configuration so as to have a radially inner flange 46 joined to a radially outer flange 47 by means of a transverse portion 48 The outer flange 47 extends the entire transverse width of the blade portion 45. The radially outer flange 47 operates in the same manner as the radially outer flange 30 of the previous embodiment In this embodiment the blade member 40 is angularly pivotable as discussed in the previous embodiment. More particularly the blade portion 40 is angularly moveable between a position as illustrated in Figure 6 and an inclined position as illustrated in Figure 7. This pivoting movement is caused by resistance encountered by the blade member 40. Typically the blade member 40 would be engaged by a resilient member such as a spring to urge the blade portion 40 back to a position at which the transverse portion 48 was located in a plane substantially normal to the rotational axis of the disc 42.

In addition to pivoting about the longitudinal axis of the blade member 40, the blade member 40 is allowed to pivot angularly about a nut and bolt 49 should the blade member 40 encounter an obstacle.

As resistance is encountered the blade member 40 pivots to the position as illustrated in Figure 7.

The blade member 40 is generally planer and extends in a plane generally perpendicular to the rotational axis of the disc 42. Accordingly noise and dust generation is reduced relative to cutting blades having inclined surfaces. The"fan"blade member 40 is only inclined when grass is encountered and therefore will only generate an air-stream for the purposes of delivering the cuttings to a catcher, when required.

The embodiment of Figures 6 and 7 has the advantage of both dust and noise reduction.

In the embodiment of Figures 8 to 13 there is schematically depicted a lawn mower disc 50 which is driven via a central aperture 51. Attached to the disc is a"fan"blade member 52 which includes a blade portion 53 and shaft 54. The shaft 54 is supported in the same manner as the shaft 27 of the embodiment of Figures 1 to 5. Accordingly in the embodiment of Figures 8 to 10 the same reference numerals have been employed.

However in this embodiment the blade portion 53 is secured to the shaft 54 by means of a threaded fastener 55.

The blade member 53 as mentioned previously would be provided to cut the grass to provide grass clippings. The blade member 53 is attached to the disc 50 by means of a threaded fastener 56. The blade member 53 has a radially outer planer portion 57 with a

leading cutting edge 58 to engage the grass to cut the grass. As also can be observed from the drawings the blade member 53 presents a minimal profile to the air through which it passes so as to minimise noise and dust creation. The blade member 52 only pivots when resistance is encountered as discussed previously. Accordingly this embodiment has the advantage of reducing dust and noise. In this embodiment the blade portion 52 is pivotally moveable between the two positions illustrated in Figure 10. That is the blade portion 52 is pivotable through 45 degrees between a generally horizontal position and a position inclined by 45 degrees to the horizontal. These angles are judged with respect to the lawn mower positioned on a generally horizontal surface. The blade portion 53 has a radially inner flange 59 joined to a radially outer flange 60 by means of a transverse portion 61. When grass is not encountered the transverse portion 61 is located in a plane generally perpendicular to the axis 62 about which the disc 50 is driven. When resistance is encountered the blade portion 52 pivots until the transverse portion 61 is inclined by 45 degrees to the position as illustrated.

In Figures 14 and 15 there is schematically depicted a disc 70 to be driven via a central aperture 71 through which a shaft passes. The shaft will be driven in a conventional manner. Attached to the disc 60 are blade assemblies including blade members 72. Each blade member 72 is supported within a housing 73 (also being part of the blade assembly) so as to be pivotable about a generally radial axis 74. Locate within each housing 73 is a spring or resilient member which would urge the associated blade member 52 to the position illustrated. Pivoting from this position would occur when the blade member 72 encounters resistance, that is engages grass to be cut.

Each blade member 72 has a lower blade portion 75 attached to an upper blade portion 76. The portions 75 and 78 are attached to a shaft 77 which enters the housing 73 to be supported.

The blade portion 76 includes a cutting element 78 which engages the grass to cut the grass to form grass clippings.

In operation of the above described blade number 72, when resistance is encountered by the lower blade portion 75, pivoting of the blade member 72 takes place about the axis 74 so that the upper blade member 76 becomes inclined and acts as a"fan" blade as well as a cutting blade. When little or no resistance is encountered the blade portions 75 and 76 are positioned as illustrated so as to cause minimal air disturbance. As increased resistance is encountered the upper blade portion 76 is pivoted to a position at which it creates an air stream to deliver the grass clippings to a catch. Accordingly noise

and dust generation is minimise. The spring or resilient means within the housing 73 would be adapted to retain the blade member 72 at a desired inclination relative to the resistance encountered. Typically the blade member 72 would pivot through 45 degrees from the position illustrated to a position at which the blade portions 75 and 76.

In the embodiment of Figures 16 to 18 there is schematically depicted a lawn mower disc 80 to be rotatably driven by a central shaft 81. Mounted on the disc 80 is a blade assembly including a housing 82 supporting a plurality of blade members 83. The blade members 83 are of a similar construction to the blade members 72 in that they include a lower blade portion 84 connected to an upper blade portion 85. The blade portions 84 and 85 are attached to a shaft 86 which is supported in the housing 82 by means of a mounting assembly 87. Each assembly 87 is pivotally mounted by means of a pin or shaft 88 so as to be angularly moveable about the pin or shaft 88 should an obstacle be encountered Each housing 87 is urged to the radial position illustrated under the influence of centrifugal force.

Each mounting assembling 87 includes a casing 89 supporting and containing a bearing 90. The bearing 90 engages the shaft 86 to provide for pivoting movement of the shaft 86 about the axis 91.

Attached to the shaft 86 is a bush 93 by means of a pin 94. Extending between the bush 93 and casing 89 is a spring 92. The spring 92 is attached to the housing 89 and bush 93 so that upon pivoting movement of the blade member 83 the spring 92 is tensioned and urges the blade member 83 to the position illustrated.

The upper blade portion 85 would be provided with a forward cutting edge 94.

In operation of the above described preferred embodiment, the blade portions 84 and 85 minimise air turbulence and therefore noise and dust creation when in the orientation illustrated As resistance increases, that is when grass is encountered, the lower blade portion 84 engages the grass and causes pivoting of the upper blade portion 85. The upper blade portion 85 cuts the grass to produce grass clippings which are then moved by the air currents produced by the upper blade portion 85 to be delivered to a grass catcher. The lower blade portion 84 may also be adapted to aid in creating air currents to transfer the grass clippings.

The spring 92 would position the blade portions 84 and 85 at a desired inclination relative to the forces encountered. Typically the blade portions 84 and 85 would pivot through 45 degrees as the resistance encountered increased.

In the above described preferred embodiments the various pivoting blade portions would preferably have the limits of their pivoting movement defined by stop surfaces.

In a further embodiment, the angular inclination of the blade members 13, 40, 41, 52, 72, 84 and 85 would be manually adjustable by operation of an adjustment member positioned on the handle of the mower.

Claims

The claims defining the invention are as follows : I A lawn mower blade member to be mounted on a rotatably driven support so as to be rotatably moved thereby about a generally upright axis, said blade member including : a mounting portion to engage the support so as to be secured thereto; a blade portion fixed to the mounting portion so as to be moved therewith, the blade portion having a longitudinal axis to have a major direction of extension radially relative to said upright axis; and wherein the blade portion in use is angularly moveable about a pivot axis extending substantially parallel to said longitudinal axis so that the blade portion is adjustable in inclination relative to air through which the blade portion is to be moved.
2. The blade member of claim 1, wherein the blade portion is angularly moveable between a position at which the blade portion is positioned in a plane substantially perpendicular to said upright axis, and an inclined position at which the

blade portion is located in a plane inclined to said upright axis by an angle of 30 to 60 ] right axis by an angle of 30 to 60 degrees.
3. The blade member of claim 2, wherein said angle is about 45 degrees.
4. The blade member of claim 1, 2 or 3, wherein the blade portion is adapted to cut grass.
5. The blade member of any one of claims 1 to 4, wherein : said mounting portion has a passage extending along said pivot access; and said blade portion has a shaft received within said passage to provide for the angular movement of the blade portion.
6. The blade member of any one of claims 1 to 5 further including a spring extending between said blade portion and mounting portion urging said blade portion to a position as which the blade portion is generally horizontally oriented so as to present a minimum profile with respect to air through which the blade portion is travelling, while permitting angular movement of said blade portion when resistance is encountered so that said blade portion becomes inclined by said angle.
7. The blade member of any one of claims 1 to 6, wherein said blade portion has a cutting edge to cut grass.
8. In combination a rotatably driven support and the blade member of any one of claims I to 6, said combination further including a cutting blade to cooperate with said blade member, said cutting blade being adapted to cut grass and said blade member being

adapted to act as a fan when resistance is encountered causing the blade member to become inclined and generate an air stream for the purposes of delivering cuttings to a catcher.
9. The blade member of any one of claims 1 to 7, wherein said blade portion includes an upper first blade part to cut grass, and a lower second blade part which upon encountering resistance causes the angular movement of said blade portion.
10. A lawn mower blade member including: a mounting portion to be secured to a rotatably driven support so that the blade member rotates about a generally upright axis; and a blade portion having a longitudinal length and transverse width and a radially outer upwardly extending flange extending substantially the width of the blade

portion.
11. The blade portion is of a"U"configuration so as to provide said radially outer flange as well as a radially inner flange space from the outer flange by means of a transverse portion.
12. A lawn mower disc and blade member substantially as hereinbefore described with reference to Figures I to 7, or Figures 8 to 10, or Figures 11 to 13, or Figures 14 and IS, Figure 16, or Figures 17 to 20.