JPH06133621A - Blade driving structure in mower - Google Patents

Abstract

PURPOSE:To provide a blade driving structure designed to suppress beat noise development due to blade rotation in a mower so constituted as to be driven by serially winding a transmission belt on plural pulleys respectively and separately interlocked with plural rotary blades. CONSTITUTION:An interlocking device is furnished by providing the respective diameters of pulleys 6, 7, 8 with differences so as to differ in rotary speed between part of plural rotary blades 3, 4, 5 and the rest thereof.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mower blade drive structure in which a transmission belt is wound in series around a plurality of pulleys which are interlockingly connected to a plurality of rotary blades.

[0002]

2. Description of the Related Art Conventionally, each pulley has the same diameter so that a plurality of rotating blades can rotate at a constant speed.

[0003]

However, in the case where a plurality of rotary blades are continuously belt-transmitted, slippage in each pulley is caused by a difference in load on each rotary blade, a difference in belt wrapping angle between pulleys, or the like. There is a difference in the rate, the rotation speed of each rotating blade is slightly different even though it is driven with the same pulley diameter, which tends to cause an unpleasant grunt noise, which is an improvement in terms of quietness. There was room. An object of the present invention is to effectively prevent howling noise from occurring when the blade is driven to rotate.

[0004]

According to a first aspect of the present invention, in a mower in which a transmission belt is wound in series around a plurality of pulleys that are interlockingly connected to a plurality of rotating blades, a part of the plurality of rotating blades is provided. This is because the interlocking device is formed by giving a difference in the diameter of the pulley so that the rotational speeds of the remaining part and the remaining part are different.

The characteristic configuration of the second invention is that in a mower in which a transmission belt is wound in series around a plurality of pulleys interlockingly connected to a plurality of rotary blades, among the plurality of rotary blades, near the outlet of the cut grass discharge path. That is, the interlocking device is formed by giving a difference in the diameter of the pulley in a state in which the one located at the position is rotated at a higher speed than the rest.

[0006]

In other words, when the cause of howling noise caused by blade rotation is investigated by various experiments, when the difference in rotational frequency between the blades becomes 2 to 3 hertz, a large howling noise is generated, and the difference in rotational frequency is Then, it was confirmed that the amount of groaning noise decreased when it was moved up or down. Based on this, we confirmed in experiments how to suppress the groaning noise, and found that the interlocking device was formed in advance in a state where the rotational speeds of some of the rotating blades and the rest were positively different. By doing so, it has been found that by making the diameters of the pulleys different so that the difference in rotational frequency between the blades is about 5 hertz, it is possible to effectively suppress the howling noise caused by the rotation of the blades. .

Further, according to the second aspect of the present invention, the blade that is located near the outlet of the cut grass discharge path and has to discharge the largest amount of cut grass rotates at a higher speed than the other blades. The discharge of grass from the grass can be surely smoothed, and the cutting grass discharge performance is also excellent.

[0008]

As a result, according to the first aspect of the present invention, it is possible to provide a lawnmower that is more excellent in quietness, in which an unpleasant grunting noise caused by the rotation of the blade can be sufficiently suppressed. Particularly, according to the second aspect of the present invention, it is possible to provide a lawnmower excellent in the performance of discharging cutgrass by effectively utilizing the structure for suppressing the howling noise.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, three rotary blades 3, 4 and 5 are arranged in parallel along a cut grass discharge path 2 inside a housing 1 having an opening at the bottom.
Pulleys 6, 7 and 8 are attached to the drive shafts 4 and 5, respectively, and a transmission belt 9 is wound around the three pulleys 6, 7 and 8 in series, and a tension pulley 10 is acted on the transmission belt 9.
The input shaft 11 that is interlocked with the central blade 3 is configured to transmit power from the PTO shaft of the machine (not shown), and cuts grass along with the drive rotation of the blades 3, 4 and 5 and cuts grass. A mower is formed to be discharged to the outside of the housing 1 from an outlet 2a on one end side of the grass discharge passage 2. The effective diameter of the pulley 6 for the central blade 3 is 150 mm, the effective diameter of the pulley 7 for the blade 4 located at the uppermost position of the cut grass discharge path 2 is 135 mm, and the blade located near the outlet 2a of the cut grass discharge path 2 is 5 by setting the effective diameter of the pulley 8 to 120mm for the rotational speed of the central blade 3 to 3000 rpm (rotation frequency 50H _Z), the rotational speed of the design of the blade 4 that is the closest expertly position of the cut grass discharge passage 2 was to 3333Rpm (rotation frequency about 55H _Z),
The designed rotation speed of the blade 5 located near the outlet 2a of the cut grass discharge path 2 is 3750 rpm (rotation frequency of about 60H
_Z ) and configure each blade 3, 4, 5 by several H
It is driven with a difference in the rotation frequency of _Z.
Incidentally, the frequency distribution of the growl sound when actually driven under the above conditions is as shown in FIG. In addition, the frequency distribution of the growl noise of the conventional example in which the effective diameters of the three rotating blades are the same (150 mm) and the number of rotations of the central blade is 3000 rpm is shown in FIG. As can be seen, according to the present invention, it is possible overall reduction of beat tones, it was possible to reduce the beat sound of 400~700H _Z.

[Other Embodiments] The number of rotary blades 3, 4, 5 installed may be two or more, and in the case of three or more, the rotation speed of at least one blade is different from the rotation speed of other blades. do it.

It should be noted that reference numerals are given in the claims for convenience of comparison with the drawings, but the present invention is not limited to the configuration of the accompanying drawings by the entry.

[Brief description of drawings]

FIG. 1 is a plan view of a mower according to the present invention.

FIG. 2 is a graph showing a drive result of a mower to which the present invention is applied.

FIG. 3 is a graph showing a driving result of a conventional mower.

[Explanation of symbols]

 2 Cutting grass discharge path 2a Exit 3,4,5 Rotating blade 6,7,8 Pulley 9 Transmission belt

Continuation of the front page (72) Inventor Hisashi Politics 64 Ishizukitamachi, Sakai City, Osaka Prefecture Kubota Sakai Factory Co., Ltd.

Claims (2)

[Claims] 1. A plurality of rotating blades (3), (4),
A plurality of pulleys (6) linked to (5) separately,
In the lawnmower in which a transmission belt (9) is wound around (7) and (8) in series, the rotary blades (3),
In the mower in which the interlocking device is formed by giving a difference in the diameters of the pulleys (6), (7) and (8) in a state where the rotational speeds of a part of (4) and (5) and the remaining part are different from each other. Blade drive structure. 2. A plurality of rotating blades (3), (4),
A plurality of pulleys (6) linked to (5) separately,
In the lawnmower in which a transmission belt (9) is wound around (7) and (8) in series, the rotary blades (3),
Of (4) and (5), the outlet (2) of the cut grass discharge path (2)
a) A mower blade drive structure in which an interlocking device is formed by giving a difference in the diameters of the pulleys (6), (7) and (8) in a state in which a nearby one rotates at a higher speed than the rest.