JPS6257285B2 - - Google Patents

Description

[Detailed description of the invention] The present invention relates to a lawn mower.

2. Description of the Related Art Rotary mowers are known, and generally a mower for driving a horizontal rotating disk is provided in the main body of the mower, and a mowing blade is attached to the horizontal rotating disk. Such mowers are often equipped with a collection bin for the grass clippings, in which case the mowing blade directly impinges on the grass clippings and, by creating a tangential air flow, moves the grass into the collection bin. It is normal to form it so that it is sent. This transfer typically takes place via a discharge chute formed by the mower body around the disk and terminating in an opening which discharges the grass clippings into a collection container.

In order to obtain a satisfactory collection effect from a mower as described above, the mower must be operated at a speed greater than that required to simply mow the grass, otherwise the airflow will be insufficient and the mowing will be interrupted. The speed is insufficient to send the harvested grass to the collection container. As a result, in addition to the loud noise generated by operating the mower's prime mover at high speed, the mowing blade itself also generates an unpleasant level of noise. A further disadvantage of conventional rotary mowers arises from the fact that the motion exerted on the cut grass is mostly tangential. Therefore, if the grass is damp, the cut grass will hit or adhere to the wall of the chute, or fall onto a shielding plate, etc., and will not be sent to the collection container. The collected grass will not be collected enough.

Therefore, the present invention aims to collect grass clippings even under various conditions more effectively than conventional methods, and relies mostly on the impact force of the blade to propel the grass clippings. Instead, the grass clippings are suspended in the air current flowing into the collection container. This has a direct noise reduction as the speed of the prime mover and mower blades can be lowered, and is actually quieter as some mower blades are not able to generate enough of the required air turbulence. The mowing blade can be designed to be a flexible mowing blade, since the mowing blade no longer needs to perform an airflow generation function.

The use of separate blades for air flow generation and mowing is described in US Pat. No. 2,953,888. This patent relates to a green forage collector and is intended to select the harvested crop by entraining it in an air stream created by a fan blade mounted on the upper surface of a conical rotary cutting disc. In this machine, air is drawn into a plurality of holes in the center of a conical hood and guided downwardly and outwardly by the conical side of the disc and the hood toward a downwardly projecting skirt around the hood's periphery. A radially disposed shield secured to the upper side of the hood near the cutting blade on the fan blade and cutting disc then directs the airflow to an exhaust orifice and exhaust tube projecting from the skirt. The downward air flow along the inner surface of the hood and skirt prevents the ingestion of foreign matter into the skirt which may mix it into the cut crop.

However, from the point of view of the present invention, mowers of this design have drawbacks with respect to noise generation and grass clipping collection. The problem of noise generation becomes even more serious because the fan blade itself generates a lot of noise when it rotates near the shield plate and the air inlet of the hood. The problem of collecting grass clippings is also exacerbated because downward outward airflow along the inner surfaces of the hood and skirt can blow grass clippings downwardly toward the ground. This blowing effect can only be prevented by closing the air inlet and relying on the propulsion force imparted to the crop by the collision with the cutting blade to cause the crop to impinge on the screen and into the discharge pipe. In contrast, the present invention generates an upward air flow around the circumferential skirt of the hood or main body by forming an annular static pressure rising chamber, and rides a swirling flow that is tangentially biased and swirls. It is intended to transport the grass clippings upwards and in the direction of rotation of the disc. Further, according to the present invention, quiet operation is ensured since there are no obstacles in the air passage.

In the mower of the present invention, the main body forms a spirally rising chute as a plenum chamber above the outer portion of the disc and the mowing blade;
The chute vents tangentially towards the discharge opening to define an unobstructed passage to the discharge opening above the outer portion of the disc, and has an air intake opening in the top of the body. , and in the main body above the disk, air is allowed to flow down from the outside toward the skirt portion through the air intake opening;
An air blower is then provided for forming a vortex of air which rises towards said chute, suspends the grass clippings within said chute, and forces it tangentially towards said discharge opening through said vortex passage. It is characterized by:

The invention will be explained with reference to the drawings.

The illustrated mower is provided with a main body 1, and this main body 1 is attached to a grounding wheel 2. A conventional push handle (not shown) may be foldable and is attached to the body 1 so that the mower can be pushed over the area to be mowed.

The main body is made of die-cast metal, for example, an aluminum alloy, and is formed with a central portion 3 forming a cylindrical vertical hole 10 within the peripheral wall 4 and the floor 5. Further, the main body 1 is formed with an annular groove-shaped chute 6 that opens downward. This chute is formed by the outer peripheral wall 8 of the main body 1 and the roof 7 of the main body. Outer wall 8
hangs below the floor 5 to form a skirt surrounding the rotating blade-disc assembly 9. This blade-disk assembly 9 is used as a prime mover, that is, a drive motor 1.
The drive motor is attached to the lower end of the upright output shaft 11 of No. 2, and the drive motor is housed in the vertical hole 10 of the main body. Especially motor 1
2 is supported on a pillar 13, which projects inward from the peripheral wall 4 and is disposed close to above the floor 5 of the vertical hole 10. The output shaft 11 is passed through from the motor 12 to below the center opening 14 of the floor. The front upper part 15 of the main body 1 extends from the upper end of the vertical hole 10 above the motor 12. An opening 15a is provided at the top of the upper front surface 15, and this opening is communicated with the inside of the vertical hole 10 to form an air passage passing through the vertical hole, so that air can flow through the opening 15a.
It is configured such that it can enter the shaft, reach around the motor 12, and pass through an opening 14 in the shaft floor.

The blade-disk assembly 9 is provided with a central disk 17 which is concentrically attached to the lower end of the motor output shaft 11 and whose rim 18 is smoothly curved upward. The rim 18 is formed to have an arcuate shape when viewed in longitudinal section (see FIG. 1), and in this cross section, the tangent to the rim forms an angle of approximately 45° with respect to the horizontal at the periphery of the disk. do. The mowing blade 19 is attached to the underside of the disc 17 by mounting bolts 21 which are spaced circumferentially apart from each other in the vicinity of the upper curved rim 18 of the disc. This bolt 21 serves as a pivot member for the blade, so that when the mower is operated, the blade is thrown outwardly by centrifugal force and radially away from the disc below and slightly outwardly from the upper curved rim 18 of the disc. Make it stand out. In this case the blade 19 is of the conventional type and is provided with an upwardly projecting rear part 19a.

A blower as a fan assembly 30 is placed above the disk 17, and this blower is placed between the disk and the underside of the floor 5. This blower is made of a plastic molded body, and consists of two overlapping annular plates 31,
32, and a number of blower blades or centrifugal fan blades 20 are arranged between these annular plates.
These blades 20 are inserted into the plate 3 from a position close to the inner edge 31a of the outer plate 31 of the motor output shaft 11.
1 in an arcuate path to a position proximate to the upwardly curved outer rim 33 of 1. The fan assembly 30 is attached concentrically to the disc 17 with screws 36, which pass through the disc 17 from the plate 32.

The upper surface of the plate 31 is slightly spaced from the bottom of the floor 5 of the shaft (this distance is exaggerated in FIG. 1 for clarity). Floor opening 14
are stacked closely above and above a central opening in the top of a fan assembly 30, the central opening of which is defined by plate 31. The dimensions of plate 31 are rim 3
3 is curved upward, passes near the outer peripheral edge of the vertical hole 5, projects upward, and is formed so as to be parallel to the rim 18 of the disc 17. The fan assembly 30 thus cooperates with the disc 17 to form a generally annular fan chamber 22 near the bottom of the floor 5 of the well and above the disc 17, with the upper side of this chamber below the disc 31. The lower side of the fan chamber is separated by the upper side of the disk 17 and the upper side of the plate 32 overlapping the disk 17. Due to the close spacing between the plate 31 and the floor 5 of the well, the fan assembly 30 provides communication only between the opening 14 and the circular outlet opening of the chamber 22 between the rims 33,18. This circular outlet opening of the fan chamber 22 communicates with the bottom of the chute 6.

The configuration of the fan assembly 30 is such that when the motor 12 is operated, air is passed through the vertical hole 10 from the front upper opening 15a.
suction around the motor in the mower, through the opening 14, outwardly from the fan chamber 22, and upwardly and outwardly in a spiral motion, into the chute 6 in the vicinity above the movement path of the mowing blade 19. Configure to send. The upward component of the motion is rim 18,3
3 is given by the upwardly curved shape. Operation of the fan assembly or air blower 30 causes the chute 6 to act as a plenum chamber with elevated static pressure relative to the outside air.

The roof 7 of the chute 6 has a spiral shape in which the height increases from the lowest part 7a to the highest part 7b according to the direction of rotation of the shaft 11, and this highest part is reached after making one rotation around the vertical hole 10, and at this point The chute 6 is opened to a discharge opening 23, and a collection container 24 is connected to the discharge opening 23. This collection container 2
4 can be made of molded plastic and is provided with a slightly elastic inlet rim 25, which rim 2
5 can be snapped into the exhaust opening 23 and is provided with an exhaust grate (not shown). When used as a mower, the air flow generated by the fan blade 20 causes the chute 6 to act as a plenum chamber, and the grass cuttings cut by the blade 19 are passed through the chute by pressurized air at a higher pressure than the atmosphere in this plenum chamber. It is pumped through the discharge opening 23 into a collection container 24 for effective collection. The mowing blade 19 is
The grass clippings are simply cut and diverted toward the upper plenum chamber or chute, and the upward movement of the grass clippings toward the discharge opening is caused by the action of the fan blades, which displace the air in the chute forming the plenum chamber. This is done by means of a vortex.

The above-described arrangement has a number of advantages over conventional mowers in which the mowing blade alone generates the airflow for transporting the grass clippings.

In particular, the strong air flow created by the fan assembly of the present invention is sufficient to direct grass clippings toward the chute 6 even when the motor 12 is operating at relatively low speeds. In FIG. 5, graph 38 plots the amount of grass collected when a mower constructed in accordance with the present invention is operated at various speeds, and graph 40 plots graph 38 when fan assembly 30 is removed. This was plotted under the same conditions as . From this figure, it can be seen that the mower according to the present invention can reach the maximum operating speed, i.e., the mower used to obtain graph 40 even at a low speed of 2500 rpm
You can see that it is better than when operating around 3500r.pm. This result is significant in that by operating the mower according to the invention at a lower speed, it produces less noise than a conventional mower. In particular, internal combustion engine driven mowers, which are typically operated at high speeds, are particularly noisy, and therefore the noise reduction provided by the present invention has important implications for such internal combustion engine driven mowers.
The noise reduction is illustrated in FIG. 4, in which graph 44 shows the noise output when operating an electrically operated mower in accordance with the present invention at various speeds. From this figure, the upper and lower limits of operating speed are 2500r.pm and 3500r.p.
It can be seen that the difference in noise output between m and m cannot be ignored.

The fact that the mower according to the invention is able to reduce noise even more than conventional mowers is not only due to the fact that it can be operated at lower speeds, but also because the design of the mower allows the airflow from the blades 19 to interact with the surface of the body 1. Benefits also arise from the fact that measures are taken to reduce the noise produced by the action. In particular, the blade 19 is placed sufficiently below the floor 5 (e.g. 50.8 mm to 101.6 mm (2 to 4 inches)) so that the outer peripheral wall 8 is located further below the floor surface of the vertical hole found in ordinary mowers. stand out. Further, in the present invention, the outer circumferential wall is configured to have a shape with few abrupt discontinuities. In particular, the wall portion 8a (see FIG. 2) adjacent to the discharge opening 23 is calculated in the direction of rotation of the disk 17 and is formed so as to be continuous with the opening 23, so that it extends from the position immediately in front of the discharge opening 23 to the axis of the shaft 11. It curves gradually and smoothly inwardly towards the end of the remaining part 8b of the wall into a substantially circular path. Thus, when the mowing blade 19 passes the end of the chute 6 adjacent the discharge opening 23, the outer end of the blade gradually approaches the vicinity of the wall 8.

The results of arranging the mowing blade at a distance from the bottom of the mower and forming the wall 8 as described above are shown in FIG. 4, which is a graph 44 showing the relationship between noise output and operating speed of the mower of the present invention. the mowing blade is closer to the underside of the mower,
There is a relatively sharp discontinuity in the wall section 8a, and at various operating speeds of conventional mowers with a wall more or less concentric to the motor axis than with the "introduction" created by the wall section 8a of the present invention. This is shown by comparing it with graph 46.

The strong airflow created by the fan assembly 30 causes the fan blades 20 to extend between opposing surfaces (in this case plates 31, 32), directing the air moving from the wells 10 to the chute 6 between these opposing surfaces and the fan blades. This is also due to the effective arrangement and positioning of the fan blades 20 to restrict flow through the space. The inner upright edge 20a of the fan blade is placed outside the central opening 14 of the floor 5, and the edge of the floor 5 forming the opening 14 is smoothly curved (see Figure 1) to allow effective air flow. to promote

Since the motor is located directly in the downward airflow in the well 10, the airflow created by the fan assembly 30 assists in displacing the motor 12.

The mower according to the invention further protects the fan blade from grass clippings, dust, and stones that wear the mowing blade, and positions the fan blade so that collection efficiency is not affected by deterioration of the mower blade. It has the advantage of being able to

Furthermore, according to the invention, the upwardly curved rim 1 of the disc 17
8 and the rim 33 of the plate 31 ensure that the upward component of the motion directs air away from the fan assembly toward the outer sphere and promotes effective collection. The swirling motion of the air created by the fan also assists in further promoting effective collection. In this connection, the fan imparts to the air by its rotational movement a large proportion of the velocity component to be thrown from the fan, and this velocity component is of course in the direction tangential to the rim of the disc.

Of course, the fan assembly may be of a different type than that shown. For example, instead of being formed as a plastic molding, the blade 20 could be formed integrally with or attached to the disk 17, and one or both of the plates 31, 32 could be omitted. The rim 18 is a plate 31
Even without the rim 33, the airflow can be directed upward by itself.

The above description merely shows embodiments of the present invention, and it goes without saying that various changes can be made within the scope of the claims.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a mower according to an embodiment of the present invention, FIG. 2 is a bottom side view of the mower of FIG. 1, FIG. 3 is a partial sectional view taken along line 3--3 in FIG. 1, and FIG. is an explanatory diagram showing the relationship between the noise output and the operating speed, and FIG. 5 is an explanatory diagram showing the relationship between the amount of collected grass and the operating speed. 1...Main body, 2...Grounding vehicle, 3...Center, 4
... Peripheral wall, 5 ... Floor, 6 ... Chute, 7 ... Roof, 8 ... Outer peripheral wall, 9 ... Blade-disc assembly, 10 ... Vertical hole, 11 ... Output shaft, 12 ... Drive Motor, 13... Support, 14... Center opening, 1
5...Front upper part, 15a...Opening, 17...Disc, 18, 31...Rim, 19...Mowing blade, 19a...Upward protruding rear part, 20...Fan blade, 21...Mounting bolt, 22 ...Fan room, 23...Discharge opening, 24...Collection container, 25
...Intake rim, 30...Fan assembly, 31,
32... Annular plate, 36... Screw.

Claims (1)

[Scope of Claims] 1. A hollow dome-shaped main body having a peripheral skirt portion projecting downward, and a prime mover attached to the main body having a drive shaft projecting downward, and supporting a horizontally disposed disk on the drive shaft. In a mower in which a plurality of mowing blades protrude from the outer peripheral edge of the disc near the skirt portion, the main body creates a spiral-shaped plenum chamber above the disc and the outer portion of the mowing blade. forming a chute which rises to the discharge opening and vents tangentially towards the discharge opening to define an unobstructed path to the discharge opening above the outer portion of the disc;
An air intake opening is provided at the top of the body, and an air intake opening is provided in the body above the disc, through which air flows down from the outside toward the skirt portion, and then through the air intake opening into the body. rising towards
Float the cut grass in this chute,
The mower further comprises an air blower that forms a vortex of air that is tangentially forced toward the discharge opening through the swirl passage. 2. An air flow opening of the blower is formed below or around the prime mover in the main body, and during operation, the blower sucks air downward from an air intake opening at the top of the main body, and this air is used to drive the prime mover. The mower according to claim 1, characterized in that the mower is configured to pass in the axial direction along the shaft. 3. The floor is configured to be driven by the drive shaft and air can be discharged to the upper surface of the disk,
3. The mower according to claim 1, wherein the disc is provided with an upwardly curved rim so as to direct the air upwardly from the blower toward the skirt portion. 4. The blower is constructed with an annular horizontal plate disposed above the circular plate, and the horizontal plate is separated from the circular plate by upright blower blades attached to both the horizontal plate and the circular plate. , wherein the center of the horizontal plate is configured to have a blower intake opening through which air sucked downward in the axial direction along the drive shaft flows during operation. The mower described in any one of these items.