JP7627429B2 - Grass trimmer - Google Patents

Description

The present invention relates to a four-wheel drive grass cutter configuration that prevents oil leakage from the axle unit between the left and right front wheels and prevents grass clippings from scattering from the openings behind the front wheels and in front of the cutting device.

Conventionally, there have been known four-wheel drive grass cutters in which the front wheels are driven by a front axle unit attached to the vehicle body in a center pivot form that can swing left and right around a pivot axis in the front-rear direction, as in Patent Document 1. These axle units adopt a form in which the steering case is fitted and pivoted to a lower fitting portion that extends downward from the transmission case at both left and right ends, and the lower fitting portion of the transmission case is inserted into a sealing member such as an oil seal or dust seal attached to the steering case and is supported by a bearing in the steering case. When the operator performs a steering operation with mud scattered by the rotation of the cutting blade attached to the sealing member, the steering case rotates around the axis of the lower fitting portion, the inner lip of the sealing member and the lower fitting portion slide against each other, and the attached mud acts as an abrasive and the sealing effect of the sealing member is lost. In particular, the lower fitting portion of the transmission case made of aluminum-based material wears out in a short time, causing a problem of oil leaking from the steering case. In addition, the front wheels of a four-wheel drive system have a wide operating range when steering, so it is necessary to leave a large gap between them and the harvesting device. This can easily scatter grass clippings, mud, and small stones, damaging the surrounding fruit trees, and bacteria in the ground or soil can attach to the fruit and leaves, making the fruit trees more susceptible to disease.

JP 2014-236675 A

The objective of the present invention is to provide a four-wheel drive grass cutter that has a simple and inexpensive configuration, prevents oil leakage problems caused by wear on the seal of the axle unit, and prevents grass clippings, mud, pebbles, etc. from scattering from the gap between the front wheels and the cutting device.

The invention described in claim 1 is a four-wheel drive grass cutter in which a cutting device K equipped with a cutting blade 4 that rotates approximately horizontally is mounted on a vehicle body 3 that suspends a pair of left and right front wheels 1,1 and rear wheels 2,2 and can be raised and lowered, and the cutting device K and the front wheels 1,1 and rear wheels 2,2 can be driven by a prime mover 5 mounted on the rear of the vehicle body 3, the front wheels 1,1 are transmitted to the vehicle body 3 by an axle unit U that is supported on the vehicle body 3 in a center pivot manner so as to be able to swing freely, a steering case 7 to which a seal member S is attached and through which lower fitting portions 6a extending downward from transmission cases 6 at both left and right ends of the axle unit U are inserted is fitted and pivoted to the lower fitting portions 6a, an elastic front cover F is provided on the front side of the axle unit U and extends downward to the vicinity of the ground across the left and right front wheels 1,1, and a front end of a cutting blade cover 8 that covers the cutting blade 4 has a seal member S that is fitted to the steering case 7 and is fitted and pivoted to the lower fitting portions 6a, An elastic outer peripheral cover 9 is provided which hangs down at a position approximately along the edge R and at a position rearward of the front wheels 1, 1, and a front-to-rear scattering prevention plate 10 is provided which hangs down from the foremost position of the rotating cutting blade 4 to a position approximately the same height as the lowest lowered cutting blade 4 on the inside left and right of the steering case 7 on the side in the direction of rotation from the foremost position of the rotating cutting blade 4, and between the elastic front cover F and the elastic outer peripheral cover 9, a pair of front and rear link arms 11, 12 which raise and lower the cutting device K are arranged on the left and right, and a link mechanism is provided which pivots the upper front ends of the link arms 11, 12 to the vehicle body 3 side and the lower rear ends to the cutting blade cover 8 side, thereby configuring the cutting device K to be raised and lowered while remaining in an approximately horizontal position, and the scattering prevention plate 10 is attached to the underside of the axle unit U with a tilt toward the rear and outward in a plan view, and the rear lower part of the scattering prevention plate 10 is cut toward the rear and upward, resulting in a grass cutter configuration.

In the invention described in claim 2, the scattering prevention plate 10 is inclined rearward and outward at an angle α in a plan view of the grass cutter.

The invention described in claim 1 is a four-wheel drive grass cutter in which a pair of left and right front wheels 1,1 and rear wheels 2,2 are suspended from the underside of a vehicle body 3, and a cutting device K equipped with a cutting blade 4 that rotates approximately horizontally is provided so as to be able to move up and down. The cutting device K and the front wheels 1,1 and rear wheels 2,2 can be driven by a prime mover 5 provided at the rear of the vehicle body 3. The front wheels 1,1 are transmitted by an axle unit U supported on the vehicle body 3 in a center pivot form so as to be able to swing freely. A steering case 7 to which a seal member S is attached and through which a lower fitting portion 6a extending downward from a transmission case 6 at both left and right ends of the axle unit U is inserted is fitted and pivoted to the lower fitting portion 6a, and a steering case 7 is provided on the front side of the axle unit U between the left and right front wheels 1,1. An elastic front cover F is provided which extends down to near the ground across the entire length of the blade cover 8, and an elastic outer peripheral cover 9 is provided at the front end of the blade cover 8 covering the blade 4, which, in a plan view, is located at a position which approximately follows the outer circumferential edge R of the rotational path of the blade 4 and at a position rear of the front wheels 1, 1.Therefore, grass clippings and mud scattered by the rotating blade 4 are blocked by the elastic front cover F which extends between the front wheels 1, 1 and are not scattered forward of the vehicle body 3, and the elastic outer peripheral cover 9 which hangs down at a position which approximately follows the outer circumferential edge R of the rotational path of the blade 4 at the front end of the blade cover 8 and at a position rear of the front wheels 1, 1 can prevent dirt and dust stirred up by the rotation of the blade 4 from being discharged forward or sideways from within the blade cover 8. In addition, a front-rear scattering prevention plate 10 is provided on the left and right inner sides of the steering case 7 on the side of the direction of rotation from the front end position of the rotating blade 4, and between the elastic front cover F and the elastic outer periphery cover 9, and extends downward to a position approximately the same height as the lowered blade 4. First, the elastic outer periphery cover 9 prevents dirt and dust from scattering forward or to the side from inside the blade cover 8, and the elastic front cover F prevents clumps of grass clippings, mud, pebbles, etc. from scattering forward in front of the vehicle body 3. The front-rear scattering prevention plate 10 prevents mud, grass clippings, dirt, etc. from scattering outward in the direction of the steering case 7 or from the gap between the front wheel 1 and the harvesting device K, preventing failure of the axle unit U due to mud adhesion and preventing scattered objects from adhering to fruit trees, etc.

Furthermore, a pair of front and rear link arms 11, 12 for raising and lowering the cutting device K are arranged on the left and right, and a link mechanism is provided in which the upper front ends of the link arms 11, 12 are pivoted to the vehicle body 3 side and the lower rear ends to the cutting blade cover 8 side, so that the cutting device K can be raised and lowered while remaining in an approximately horizontal position.Since the scattering prevention plate 10 is attached to the underside of the axle unit U, the scattering prevention plate 10 attached to the axle unit U side moves up and down less than if it were attached to the cutting blade cover 8 side, which rises and falls.In addition, since the rear lower part of the scattering prevention plate 10 is cut toward the rear and upward, the scattering prevention plate 10 does not get caught on grass or the ground when reversing, and mud and cut grass can be stably prevented from scattering.

In the invention described in claim 2 , the anti-scattering plate 10 is inclined rearward and outward at an angle α when viewed in a plane, so that when traveling in reverse, the lower part of the anti-scattering plate 10 is reliably curved outward, thereby stably maintaining prevention of mud and grass clippings from scattering.

FIG. FIG. FIG. 4 is a plan view showing the wheel transmission mechanism and the anti-scattering configuration. FIG. 4 is an overall side view showing the lifting and scattering prevention structure of the harvesting device.

The seat 15 on which the operator sits is provided in the center of the vehicle body 3, and the mower K, which can be raised and lowered, is provided on the lower abdomen of the seat 15. In front of the seat 15, there are an axle unit U attached to the vehicle body 3 in a center pivot form that can swing left and right around a pivot axis P in the fore-and-aft direction, front wheels 1, 1 provided on the left and right of the axle unit U, and a handlebar 16 that allows the operator seated on the seat 15 to steer the front wheels 1, 1. The handlebar 16 is supported by a handlebar post 14, and a step 13 is provided between the lower end of the handlebar post 14 and the seat 15. The handlebar post 14 is provided with a key switch for starting the motor 5, an accelerator lever for manual operation, a travel change lever, a choke lever, an hour meter, etc. (not shown). The motor 5 is provided behind the seat 15, and the power of the motor 5 is transmitted to the mower K to rotate the mower blade 4 and cut grass. The power of the prime mover 5 is also transmitted to a hydraulic continuously variable transmission (HST) 18 for traveling provided below the prime mover 5, and drives the rear wheels 2, 2 via a transmission case 17. The hydraulic pressure of the HST 18 drives a front axle unit U through a hydraulic hose 19, enabling the vehicle to travel in four-wheel drive mode. The prime mover 5 has an output shaft 20 protruding downward, and attached to the output shaft 20 are a blade V-belt 21 for driving the mower K and the HST 18, and an engine pulley 23 around which a traveling V-belt 22 is wound. The blade V-belt 21 is wound between the engine pulley 23 and a blade pulley 25 attached to the upper end of a blade shaft 24 of the mower K, and the power transmission to the blade pulley 25 can be turned on and off by tensioning or loosening the blade V-belt 21 with a tension pulley 26. A cutting blade 31 is attached to the lower end of the blade shaft 24, and the cutting blade 4 is pivoted to both ends of the cutting blade 31.

The mowing device K is attached to a pair of front and rear link arms 11, 12 that are suspended from the vehicle body 3, and the link arms 11, 12 are also provided on the left and right, with the upper front side of the link arms 11, 12 pivoted to the vehicle body 3 side and the lower rear side pivoted to the cutting blade cover 8 side of the mowing device K. When the operator operates the lifting lever 27 up and down, the mowing device K can be raised and lowered in a substantially horizontal state via the lifting link mechanism 28. The link mechanism with the link arms 11, 12 provided on the left and right allows the mowing device K to be raised and lowered while maintaining a substantially horizontal state. An elastic outer periphery cover 9 is provided at the front end of the mowing device K across the left and right width of the cutting blade cover 8. The elastic outer periphery cover 9 is made of an elastic material such as rubber or resin, and in the left-right center, it hangs down in a position that is approximately along the outer periphery R of the rotation trajectory of the blade 4 in a plan view, and in the rear of the front wheels 1, 1, the elastic outer periphery cover 9 hangs down in the horizontal direction in a plan view, and the hanging length 9h is set to approximately 1/2 the side height 8h of the blade cover 8. The elastic outer periphery cover 9, which hangs down from the top surface of the blade cover 8 to approximately 1/2 the side height 8h of the blade cover 8, does not hinder the grass-raising performance from the front, and prevents dust and other particles that fly up inside the blade cover 8 from being released to the periphery of the blade cover 8, especially in the forward direction.

The axle unit U is equipped with a hydraulic motor 33 in the left and right central portion, and the output from the hydraulic motor 33 is transmitted from the axle shaft 34 through gears 35 and 36 in the transmission case 6, through the transmission shaft 37 to gears 38 and 39, to the wheel shaft 40 and wheel boss 41, driving the front wheels 1. The transmission cases 6 at both left and right ends of the axle unit U form lower fitting parts 6a extending downward, and the lower fitting parts 6a are fitted into the seal member S and bearing 42 at the upper end of the steering case 7 and the bearing 43 at the lower end, and the steering case 7 is supported so that it can rotate freely around the lower fitting parts 6a. The steering case 7 allows the driver to steer the front wheels 1, 1 via the steering rod 44 and the connecting rod 48 that connects the left and right steering cases 7, 7 by rotating the handlebars 16. The inside of the transmission case 6, steering case 7, and side case 45 are filled with oil, and this oil is connected to the operating oil path of the HST 18. The amount of oil is up to a level where air can escape from the air bleed bolt 46 hole at the top end of the steering case 7 (oil level L), which means that the oil is filled to a level higher than the sealing part of the seal member S.

3, most of the grass cut by the blade 4, which rotates to the right in plan view, is discharged from the outlet 29 at the rear right side of the blade cover 8 (forward of the right rear wheel 2) or from the rear center of the blade cover 8, but some grass clippings may be discharged from the front of the blade cover 8 or from the gap 30 between the right front wheel 1 and the blade cover 8 behind it. Grass clippings that are scattered and discharged in front of the blade cover 8 are blocked by an elastic front cover F that hangs down to a position close to the ground J and spans between the left and right front wheels 1, 1 on the front side of the axle unit U, and mud and grass clippings that are scattered in the direction of the transmission case 6 of the axle unit U are blocked by a scattering prevention plate 10 attached to the axle unit U side between the elastic outer periphery cover 9 and the elastic front cover F. The scattering prevention plate 10 is made of an elastic material such as rubber or resin, and is attached to the protective cover 47 below the axle unit U in the fore-and-aft direction, and hangs down to a height approximately equal to that of the lowered cutting blade 4 and the elastic front cover F. A gap 32 is provided between the elastic front cover F and the front end of the scattering prevention plate 10 so as not to hinder the elastic front cover F from bending or curving backward during grass cutting work while traveling forward. Furthermore, the scattering prevention plate 10 is provided with an inclination α toward the rear right and outward in a plan view, and the rear lower part is cut toward the rear and upward, so that the scattering prevention plate 10 does not get caught on the ground J or grass when traveling backward, and the lower part of the scattering prevention plate 10 reliably bends toward the right and outward when traveling backward, and the scattering prevention of mud and grass clippings can be stably maintained. The link mechanism consisting of the link arms 11, 12 that raise and lower the mower K causes the mower K to move backward when raised and forward when lowered, so if a gap is formed between the scattering prevention plate 10 and the elastic outer periphery cover 9, grass clippings, mud, pebbles, etc. may scatter to the right side from the gap. Considering the scattering prevention effect, it is preferable that no gap is formed no matter what state the mower K is in, but if the front end of the cutting blade cover 8 or the front part of the elastic outer periphery cover 9 contacts the scattering prevention plate 10 when the mower K is in the lowest position, the scattering prevention plate 10 made of elastic material will deform and the scattering prevention effect of the grass clippings and mud will not be stable. Therefore, the mower is configured so that the front end of the cutting blade cover 8 or the front end of the elastic outer periphery cover 9 will not contact the scattering prevention plate 10 and cause significant deformation even when the mower K is in the lowest position, i.e., when the mower K is moved to the most forward position. As shown in FIG. 4, the shatterproof plate 10 can be expected to have the same effect even if the cut shape of the lower rear part is a straight line (a), a curved, rounded shape (b), or a polygonal shape (c).

When grass clippings or mud adhere to the seal member S as the cutting blade 4 rotates, they get in between the lower fitting 6a of the transmission case 6 and the lip on the inside of the seal member S. The mud in particular acts as an abrasive, causing wear in a short period of time on the lip or the lower fitting 6a, which is made of an aluminum-based casting material. Because the oil level L inside the transmission case 6 is filled to a level higher than the seal member S, there is a problem that if the sealing effect of the seal member S weakens, the oil inside will leak out. In this grass cutter, an elastic front cover F is provided on the front side of the axle unit U, extending downward to the vicinity of the ground between the left and right front wheels 1,1, an elastic outer periphery cover 9 is provided on the front end of the blade cover 8 covering the blade 4, in a plan view, at a position that is approximately along the outer periphery R of the rotation path of the blade 4 and at a position rearward of the front wheels 1,1, and a scattering prevention plate 10 is provided in the front-rear direction, extending downward to a position approximately equal to the height of the lowered blade 4 on the left and right inner sides of the steering case 7 on the side in the direction of rotation from the front end position of the rotating blade 4, and between the elastic front cover F and the elastic outer periphery cover 9. Figure 4 shows the state in which the cutting device K is lowered to the lowest position, with the scattering prevention plate 10 extending downward to a position approximately equal to the height of the blade 4. With this configuration, grass clippings and mud scattered by the rotating blade 4 are blocked by the elastic front cover F spanning between the front wheels 1,1, and are not scattered forward of the vehicle body 3, and the elastic outer peripheral cover 9 that hangs down from the front end of the blade cover 8 in a position that roughly follows the outer peripheral edge R of the rotational trajectory of the blade 4, and at a position rearward of the front wheels 1,1, prevents dirt stirred up by the rotation of the blade 4 from being scattered forward or to the side from within the blade cover 8. In addition, a front-rear scattering prevention plate 10 is provided on the left and right inner sides of the steering case 7 on the side of the rotation direction from the front end position of the rotating blade 4, and between the elastic front cover F and the elastic outer periphery cover 9, and extends downward to a position approximately the same height as the lowered blade 4. Therefore, the elastic outer periphery cover 9 first prevents dirt and dust from scattering forward or to the side from the blade cover 8, and the elastic front cover F prevents clumps of grass clippings, mud, and pebbles from scattering forward of the vehicle body 3. The front-rear scattering prevention plate 10 prevents mud, grass clippings, dirt, etc. from scattering toward the right steering case 7 or outward from the gap 30 between the right front wheel 1 and the cutting device K, and also prevents failure of the axle unit U due to mud adhesion.

In addition, a pair of front and rear link arms 11, 12 are arranged on the left and right, and the upper front ends of the link arms 11, 12 are pivoted to the vehicle body 3 side and the lower rear ends to the blade cover 8 side by a link mechanism that allows the cutting device K to be raised and lowered while remaining in a substantially horizontal position. The anti-scattering plate 10 is attached to the underside of the axle unit U, which is tilted rearward and outward in a plan view, so that the anti-scattering plate 10 attached to the axle unit U side moves up and down less than if it were attached to the blade cover 8 side, which rises and falls. Also, because the rear lower part of the anti-scattering plate 10 is cut rearward and upward, the anti-scattering plate 10 does not get caught on grass or the ground when traveling backward, and a stable effect of preventing mud and grass clippings from scattering can be obtained.

In addition, because the elastic front cover F and the front end of the scattering prevention plate 10 are positioned apart, even if the elastic front cover F curves or bends backwards due to contact with grass or the ground while moving forward, the gap 32 on the front side of the scattering prevention plate 10 prevents the scattering prevention plate 10 from interfering with the bending or bending of the elastic front cover F in the front-to-rear direction, allowing the elastic front cover F to maintain good ability to capture uncut grass and prevent cut grass from flying forward.

REFERENCE SIGNS LIST 1 Front wheel 2 Rear wheel 3 Vehicle body 4 Cutting blade 5 Prime mover 6 Transmission case 6a Lower fitting portion 7 Steering case 8 Cutting blade cover 9 Elastic outer periphery cover 10 Scattering prevention plate 11 Link arm 12 Link arm F Elastic front cover K Cutting device R Rotational locus outer periphery U Axle unit
α Tilt

Claims (2)

A mower (K) having a cutting blade (4) that rotates approximately horizontally is provided on the underside of a vehicle body (3) that suspends a pair of left and right front wheels (1), (1) and rear wheels (2), (2) so as to be movable up and down, and the mower (K) and the front wheels (1), (1) and rear wheels (2), (2) are driven by a prime mover (5) provided at the rear of the vehicle body (3). In this four-wheel drive grass cutter, the front wheels (1), (1) are supported by an axle unit that is swingably supported on the vehicle body (3) in a center pivot configuration. A steering case (7) is fitted with a seal member (S) for inserting a lower fitting portion (6a) extending downward from a transmission case (6) at both left and right ends of the axle unit (U) and is pivotally supported by the lower fitting portion (6a). An elastic front cover (F) is provided on the front side of the axle unit (U) and extends downward to the vicinity of the ground between the left and right front wheels (1, 1). A blade cover (8) for covering the blade (4) has a front end portion having a seal member (S) for inserting a lower fitting portion (6a) extending downward from the transmission case (6) at both left and right ends of the axle unit (U) and is pivotally supported by the lower fitting portion (6a). An elastic outer circumferential cover (9) is provided at a position approximately along the outer circumferential edge (R) of the rotation trajectory of the front wheel (1), (4), and at a rear portion of the front wheel (1), (1), and a front-rear scattering prevention plate (10) is provided on the left and right inner sides of the steering case (7) on the side in the direction of rotation from the front end position of the rotating cutting blade (4) and between the elastic front cover (F) and the elastic outer circumferential cover (9) to a position approximately the same height as the lowered cutting blade (4) , and before raising and lowering the cutting device (K), A pair of rear link arms (11, 12) are arranged on the left and right, and a link mechanism is provided in which the upper front ends of the link arms (11, 12) are pivotally supported on the vehicle body (3) side and the lower rear ends are pivotally supported on the blade cover (8) side, thereby enabling the cutting device (K) to be raised and lowered while remaining in a substantially horizontal position, and a scattering prevention plate (10) is attached to the underside of the axle unit (U) and the rear lower portion of the scattering prevention plate (10) is cut toward the rear and upward . 2. The grass cutter according to claim 1, wherein the scattering prevention plate (10) is inclined (α) rearward and outward in a plan view.

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