Mower blade

Mower blade utilizes a blade portion formed on the blade main body and an air circulator portion formed on the blade main body and generating airflow via rotation centered around the vertically-oriented axis of the mower blade. The blade portion is arranged in a length-direction end portion of the blade main body and extends along a predetermined area in the length-direction. The air circulator portion is located opposite the blade portion in a width direction, has a rising upward portion, and extends along a predetermined area in the length-direction. A boundary portion is arranged between the blade main body and a rising upward portion of the air circulator portion has a portion inclined or angled with respect to the blade portion such that, beginning at the length-direction end portion, a distance between the boundary portion and the blade portion increases along the length-direction and moving toward the vertically-oriented axis. A height of an upper end portion of the air circulator portion measured from a surface of the blade main body is a substantially constant height.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 of Japanese Application No. 2013-004912, filed on Jan. 15, 2013, the disclosure of which is expressly incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a mower blade such as a mower blade that can be rotatably driven and centered around a vertically-oriented axis in an interior of a housing.

2. Description of Related Art

A mower blade generates airflow within a housing using fan blades, with the airflow causing grass to stand upright in order to facilitate cutting, transporting the cut grass, and the like. Conventionally, this type of mower blade is described in documents such as Japanese Patent Laid-open Publication No. S61-135515 and U.S. Pat. No. 4,559,769, for example. Japanese Patent Laid-open Publication No. S61-135515 and U.S. Pat. No. 4,559,769 describe a rotary mower blade as the mower blade. The mower blade of Japanese Patent Laid-open Publication No. S61-135515 includes a cutting blade formed along a long side of a plate-shaped member and a fan blade extending parallel to the cutting blade. The mower blade of U.S. Pat. No. 4,559,769 includes a cutting blade and a fan blade. At each of two apexes of the substantially rectangular plate-shaped member, the two apexes lying along a diagonal line, the mower blade includes cutting blades spanning a predetermined area beginning at the apex and following the long side of the plate-shaped member. At two apexes lying along another diagonal line, a vicinity of the apex is given a notched shape. A predetermined area including the notched portion is folded back across the adjacent long and short sides of the plate-shaped member such that the predetermined area including the notched portion stands upright, thus forming a trapezoidal fan blade.

In the mower blade disclosed in Japanese Patent Laid-open Publication No. S61-135515, the fan blade extends parallel to the cutting blade formed along the long side of the plate-shaped member. In other words, the fan blade extends parallel to a length direction of the mower blade. Therefore, airflow caused by the fan blade moves in a rotation direction (a direction tangential to a rotation trajectory of an outside end of the mower blade) or even further outward than the rotation direction. Therefore, the mower blade may not be able to generate sufficient airflow in a transport direction of the cut grass. Meanwhile, in comparison to the fan blade extending parallel to the cutting blade formed along the long side of the plate-shaped member, the configuration described above for the mower blade of U.S. Pat. No. 4,559,769 includes the fan blade facing an interior of the rotation direction of the mower blade. Airflow directed further inward than the rotation direction (the direction tangential to the rotation trajectory of the outside end of the mower blade) can thus be caused, thus generating airflow in the transport direction of the cut grass. However, in the mower blade of U.S. Pat. No. 4,559,769, a space between a lateral side of the fan blade facing a mowing chamber wall and an opposing lateral side of the fan blade decreases toward an end of a fan blade extending from a blade main body, thus creating a tapering shape to the fan blade. Thus, insufficient airflow may be generated and a desired air circulation performance may be difficult to achieve.

In view of the above circumstances, there is an urgent need for a mower blade capable of generating airflow in an appropriate direction with superior air circulation performance.

SUMMARY OF THE INVENTION

The mower blade of the present invention includes a mower blade rotatably driven and centered around a vertically-oriented axis in an interior of a housing. The mower blade includes a blade main body, a blade portion formed on the blade main body, and an air circulator portion formed on the blade main body and generating airflow by rotation centered around the vertically-oriented axis of the mower blade. The blade portion spans from a length-direction end portion of the blade main body to a predetermined area. The air circulator portion is formed on a width-direction side of the blade main body opposite the blade portion, rising up and bent with respect to the blade main body from the length-direction end portion to a predetermined area. A boundary portion between the blade main body and a rising portion of the air circulator portion is inclined with respect to the blade portion such that, beginning at the length-direction end portion, the boundary portion grows more distant from the blade portion as the boundary portion approaches the vertically-oriented axis center. The air circulator portion spans from the length-direction end portion of the blade main body to a predetermined area such that an upper end portion of the air circulator portion has substantially a fixed height.

Herein, “an upper end portion of the air circulator portion has substantially a fixed height” may refer to a height that is effectively (though not exactly) the same. Specifically, a difference between the heights of a highest portion and a lowest portion of the height may be 30% or less of the height of the highest portion. As described above, the air circulator portion faces the interior of the rotation direction of the mower blade and can generate airflow that is directed more towards an interior than the rotation direction of the mower blade (a direction tangential to a rotation trajectory of an outside end of the mower blade). In addition, the air circulator portion spans from the length-direction end portion of the blade main body to the predetermined area such that the upper end portion of the air circulator portion has substantially a fixed height. Therefore, surface area of the air circulator portion can be increased and a space between a mowing chamber wall and the air circulator portion can be reduced. Thus, a mower blade capable of generating airflow in an appropriate direction with superior air circulation performance can be obtained.

In the above-noted configuration, a distance on the length-direction end from a cutting edge of the blade portion to the boundary portion is substantially equal to a distance, on the vertically-oriented axis center side end of the blade portion, from the cutting edge of the blade portion to a center line in the width direction of the blade main body. Specifically, in the present configuration, although the air circulator portion faces the blade portion, the distance on the length-direction end portion closest to the blade portion and the air circulator portion from the cutting edge of the blade portion to the rising portion of the air circulator portion is substantially equal to the distance on the vertically-oriented axis center side end of the blade portion from the cutting edge of the blade portion to the center line in the width direction of the blade main body. Therefore, a sufficient sharpened area of the blade portion can be reserved and the mower blade can be used for a longer time.

In the above-noted configuration, in a plan view, the boundary portion is bent in a direction increasing the inclination of the boundary portion with respect to the blade portion at an intermediate portion, and the air circulator portion is bent at a location corresponding to the bent portion. By bending the air circulator portion in the above way, strength of the air circulator portion can be increased.

DETAILED DESCRIPTION OF THE INVENTION

In the following description, an exemplary embodiment is described in which an embodiment of the inventive mower blade is applied to a riding lawn mower. As shown inFIG. 1, the riding lawn mower can be of the type that includes a vehicle body, a pair of left and right front wheels1, a pair of left and right rear wheels2, a motor section having an engine E, a cockpit in which a driver's seat4is installed behind the motor section, and a travel speed changing mechanism.

A propulsion mechanism5is utilized to change a speed of a drive force from the engine E and transmits the drive force to the front wheels1and rear wheels2. Specifically, the propulsion mechanism5can include a hydrostatic continuously variable transmission (not shown in the drawings) that can switch the drive force from the engine E between forward and reverse travel speeds using the hydrostatic continuously variable transmission. The switched drive force can thus be transmitted to the front wheels1and the rear wheels2. Moreover, speed for the drive force from the engine E can be continuously changed in both forward travel and reverse travel.

In the exemplary embodiment, a mower10is coupled to a vehicle body frame6of a vehicle body via a link mechanism7and is positioned between the front wheels1and the rear wheels2(below the vehicle body). A rear link7aon the link mechanism7is also utilized which can swing up and down via a lift cylinder (not shown in the drawings). The link mechanism7can thus be lifted and lowered to control elevation of the mower10between a lowered work state (in which one or more gauge wheels11are in contact with a ground surface) and a raised idle state (in which the gauge wheels11hover above the ground surface). When the mower10is in the lowered work state, mower blade13located in an interior of a housing12of the mower10is rotated, thereby performing a mowing process on grass (or a lawn) while the mower blade13is located in the interior of the housing12of the mower10.

As shown inFIGS. 2 and 3, the mower10includes the mower housing12, a plurality of mower blades13, and the like. Each mower blade13is arranged in the interior of the mower housing12so as to be rotatable around a vertical axis center “p”. In the present embodiment, three mower blades13are aligned in a left-right direction, with each mower blade13being arranged on or mounted about a corresponding vertically-oriented rotation shaft14. A baffle plate15having a wavy shape is utilized that follows a front side of the rotation trajectory traced by each of the mower blades13and is located on a front side of the mower housing12interior. A vacuum plate16having a wavy shape that follows a rear side of the rotation trajectory traced by each of the mower blades13is located on a rear side of the mower housing12interior. An exhaust mouth17is provided on a right end of the mower housing12to allow for the expelling of the cut grass. Power from a power transfer shaft5aof the propulsion mechanism5is input through an intermediate shaft19to an input shaft18provided above the mower housing12. The power input to the input shaft18is transmitted through a belt-type power distribution mechanism8to each of the rotation shafts14. Each mower blade13is then driven to rotate around the vertical axis center “p”.

Moreover, in the present embodiment, the three mower blades13are positioned in a triangular layout such that the center mower blade13is located further forward than the left and right mower blades13(seeFIGS. 2 and 3). In this way, portions of the rotation trajectories traced by neighboring mower blades13can overlap in the left-right direction.

A structure of the mower blades13will now be described with reference toFIGS. 4-7withFIG. 4showing a perspective view of the mower blade,FIG. 5showing a lateral view from one end of the mower blade,FIG. 6showing a plan view andFIG. 7showing a cross-sectional view of a portion of the blade13. As shown inFIGS. 4 and 5, each blade13can have a blade main body20that includes, along a length direction, a first portion21having a hole30for mounting to a rotation shaft14. A second portion22of the body20has a blade portion31and an air circulator portion32. A third portion23is located between the first portion21and the second portion22. Moreover, the first portion21can be positioned higher than the second portion22while the third portion23is inclined so as to decrease in height from the first portion21toward the second portion22. As shown inFIG. 6, the leading edge of the blade main body20, in terms of the direction of rotation of the blade13, that is, along the first, second, and third portions, extend in a straight line.

As shown inFIG. 4, the second portion22and the third portion23can each be located at two opposite sides of the first portion21. In other words, the first portion21is positioned at a center of the body20in the length direction while the third portion23is positioned on both outer sides of the first portion21, and the second portion22is positioned on the outer side of each of the third portions23. In the present embodiment, the blade main body20can be a single plate-shaped member and the first portion21, the second portion22, and the third portion23are formed by bending this plate-shaped member.

Referring again toFIG. 4, it can be seen that each of the second portions22includes the blade portion31and the air circulator portion32. The blade portion31and the air circulator portion32are formed on respective, mutually diagonal lines on the second portion22. Thus, the blade portion31is located on a front side (in the rotation direction) and the air circulator portion32is located on a rear side.

Referring toFIGS. 6 and 7, it can be seen that a portion of the second portion22on the blade main body20is bent upward, thus forming the air circulator portion32. As is shown inFIG. 6, a boundary portion34(rising portion) is located between the blade main body20and the air circulator portion32and extends at an inclination such that, beginning at a length-direction end portion of the blade main body20, the boundary portion34grows more distant from the blade portion31as the boundary portion34approaches a center of the blade main body20, and such that, beginning at a width-direction intermediate portion of the blade main body20, the boundary portion34approaches a width-direction end portion of the blade main body20on a side opposite the blade portion31. The boundary portion34then intersects with the end portion (reaches the end portion). The boundary portion34also bends at an intermediate portion thereof so as to suddenly incline greatly toward the end portion of the blade main body20on the side opposite the blade portion31. Similarly, the air circulator portion32extends at an inclination such that the air circulator portion32approaches the width-direction end portion of the blade main body20on the side opposite the blade portion31. The air circulator portion32then bends at an intermediate portion thereof. The result is that a bent line35can be formed running from an upper end of the air circulator portion32to a bend34ain the boundary portion34.

Referring back toFIG. 5, it can be seen that, in a lateral view, a height H (from a flat portion of an upper surface of the second portion22to an upper end of the air circulator portion32) can be substantially the same over an area L2running from the end portion to the bend34a(the upper end is substantially horizontal in the area L2). The height H then gently lowers or decreases in area L3from the line of bending toward the width-direction end of the blade main body20on the side opposite the blade portion31. As described above, the air circulator portion32can span from the end portion to the intermediate portion of the second portion22.

It should be noted herein that the phrase “roughly the same height” as used herein may refer to a height that is effectively or approximately (though not exactly) the same. Specifically, a difference between the heights of a highest portion and a lowest portion of the height H may be 30% or less of the height of the highest portion. The difference is preferably 15% or less and is more preferably 10% or less. While not intended to be limiting, in the above-described embodiment, L2may be 50% or more of L1, can preferably be 60% or more of L1, and is more preferably 70% or more of L1. In other words, by providing an area L2where the height H is substantially the same across a somewhat lengthy area, airflow can be generated with stability.

As noted above, the length L1along the length direction of the air circulator portion32is defined to be shorter than the length L along the length direction of the blade portion31. Specifically, the length of L1can be defined at approximately 25% to 75% of the length L, and is preferably defined at approximately 45% to 70% of the length L.

In other words, the length L1of the air circulator portion32is defined to be a length necessary to achieve a required air circulation force while being defined to be shorter than the length L of the blade portion31. By defining the length L1of the air circulator portion32in this way, the air circulator portion32can be inclined with respect to the cutting edge of the blade31without occupying a large amount of space in the width direction of the blade main body20. Therefore, a distance from the cutting edge of the blade portion31to the boundary portion34can be made larger. Thus, a sharpened area of the blade31can be larger and the mower blade13can last longer.

While not intended to be limiting, with the above-described configuration shown inFIG. 6, the above-described embodiment can include an air circulator portion32in which a distance Y1(between the cutting edge on the outer end portion of the blade portion31and the boundary portion34) and a distance Y (between the cutting edge on the length-direction center-side end portion of the blade portion31and the center line C) are substantially equal. Herein, “substantially equal” may refer to Y1and Y being effectively or approximately (though not exactly) equal. Specifically, Y1can be defined at approximately 60% to 140% of Y, is preferably 70% to 130% of Y, and is more preferably 80% to 120% of Y.

Although not intended to be limiting, as shown inFIG. 6, an angle θ1can be utilized between the boundary portion34and the cutting edge of the blade portion31and can be approximately 10° to 30°, and is preferably defined to be approximately 15° to 25°, and more preferably is defined to be approximately 20°. By defining the angle θ1in this way, the air circulator portion32can generate an airflow W (seeFIG. 3) that is directed more towards an interior than a direction following the rotation direction of the mower blade13(a line tangential to the rotation trajectory of the outside end of the mower blade13). Thus, as shown inFIG. 3, airflows W1and W2in adjacent portions of adjacent mower blades13can be inhibited or prevented from interfering with each other. As a result, the airflows W1and W2, which are directed in mutually opposing directions, can be prevented from weakening each other's circulation force. In addition, disruption of the air current can be prevented. Thus, cut grass can be adequately transported while achieving reductions in rotation driving force and energy use.

Although the above-described embodiment is described with reference to an exemplary riding mower, e.g., having the mower10located between the front wheels1and the rear wheels2(below the vehicle body), the mower blade13can be used on other mowers and is not limited to the above riding mower. For example, the blade may be utilized on a riding mower having the mower10positioned on either a front or back of the vehicle body. The mower blade13can also be utilized on a push mower.

The inventive features of the present invention can thus be utilized on a mower blade for different types of mowers.