JP2008141958A - Rotating member support unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rotating member support unit which can always maintain the internal pressure, at substantially the same pressure as the atmospheric pressure, can prevent external leakage of grease, and can stably rotate the rotating member at fixed rotational accuracy, over a long period. <P>SOLUTION: This rotary member-support unit U1 comprising a main shaft 8, bearings 2, 4 for supporting the main shaft, gears G1, G2 for transmitting the rotational force of a driving shaft 38 to the main shaft, a rotating member 32, and a receiving case 40, and further having an inner pressure-adjusting mechanism for substantially keeping the inner pressure fixed at a substantially approximately the same pressure as the atmospheric pressure, is characterized by disposing an inner pressure-adjusting chamber 20 which can discharge an inner gas to the outside on the increase of the inner pressure, charge the outer air to the inside on the decrease of the inner pressure, always adjust the inner pressure to a substantially the same pressure as the atmospheric pressure, and collect and store a lubricant, communicating the inner portion with the inner portion of the unit by means of the communication holes 40h of the case, disposing opened holes 20k for making the inner portion of the unit communicate with the outside, dividing the inner portion into divided chambers 61, 62 and 63 with bulkheads 71, 72, and communicating the insides of the divided chambers 61, 62, 63 with each other through air holes 71h, 72h penetrated though the bulkheads. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to, for example, a grass cutter, a brush cutter and a lawn mower, or an electric tool used for cutting off a plant (e.g., lawn or weed) growing on the ground surface from the vicinity of the root. The present invention relates to an improvement of a rotary member support unit that pivotally supports a rotary member such as a cutting blade (rotary blade).

FIGS. 2A and 2B show an example of a configuration of a mower provided with such a rotating member support unit. In the configuration shown in the figure, the mower A includes an operation tube 30 that extends linearly, and a rotary member support unit (hereinafter referred to as a rotary blade unit) U2 provided on one end side of the operation tube 30. A driving device (engine) 34 provided on the other end side of the operation tube 30 is provided.
In this case, the operation tube 30 is provided with a drive shaft 38 that is rotated by a drive force (rotational output) generated by the engine 34, and the drive shaft 38 is a rolling bearing (hereinafter referred to as drive shaft). (Referred to as a bearing) 6 is rotatably supported. A gear (hereinafter referred to as a drive shaft gear) G1 is provided at the end of the drive shaft 38 opposite to the engine 34, and the drive shaft bearing 6 is externally fitted to the drive shaft gear G1. The drive shaft 38 is rotatably supported.

  Further, the rotary blade unit U2 includes a main shaft 8 extending in a predetermined direction and two rolling bearings (hereinafter referred to as the rotary blade side bearing 2 (FIG. 2B)) that rotatably support the main shaft 8. In order to transmit the rotational force of the drive shaft 38 to the main shaft 8 (on the lower side bearing) and the gear side bearing 4 (upper bearing in the figure). A pair of gears (referred to as drive shaft gear G1 (right side gear in the figure) and main shaft gear G2 (left side gear in the figure)) provided on the left end side and the upper end side in FIG. And a rotatable rotating member (cutting blade) 32 attached to the other end side of the main shaft 8 (lower end side in the figure).

In this case, the main shaft 8 is erected so as to extend in a substantially vertical direction when the mower A is in use, and the drive shaft 38 has a predetermined inclination angle (drive shaft 38 with respect to the main shaft 8). And an angle formed between the main shaft 8 and the main shaft 8 and is connected to the main shaft 8 via the drive shaft gear G1 and the main shaft gear G2.
Further, the rotary blade side bearing 2 is positioned between the cutting blade 32 and the main shaft gear G2 in the middle of the extending direction of the main shaft 8, or in another way, while the gear side bearing 4 is It is positioned at the end of the main shaft 8 opposite to the cutting blade 32 (upper end in FIG. 2B). Further, the operation tube 30 is provided with a protective cover 42 for protecting the operator from the cutting blade 32 at a predetermined position near the cutting blade 32.

  According to such a configuration, when the engine 34 rotates the drive shaft 38, the rotational force is transmitted to the main shaft gear G2 via the drive shaft gear G1, and the main shaft 8 can be rotated by the rotational force. Thereby, while changing the direction of the rotational force generated from the engine 34, the cutting blade 32 attached to the main shaft 8 can be rotated while the speed is reduced. The operator can cut the vegetation by moving the cutting blade 32 while supporting the whole of the mower A by the operation handle 36 attached to a predetermined position of the operation tube 30 near the engine 34.

  By the way, regarding such a mower, various measures for improving convenience and safety have been conventionally known. For example, Patent Document 1 discloses a configuration of a mower capable of arbitrarily changing the angle of a connection pipe (operation pipe), thereby facilitating the mowing of vegetation even on sloping ground. And the convenience of the mower is improved. On the other hand, for example, Patent Document 2 discloses a configuration of a mower capable of easily and reliably attaching a cutting blade (rotating blade) to a main shaft, whereby the cutting blade (rotating blade) can be removed from the main shaft. It is possible to effectively prevent the detachment and improve the safety of the mower.

  Further, in this mower A, the friction and wear of the portions where the teeth of the drive shaft gear G1 and the main shaft gear G2 contact each other are reduced, and the rotary blade side bearing 2, the gear side bearing 4 and the drive shaft bearing 6 are prevented from seizing. For the purpose of extending the fatigue life, etc., the gears G1, G2 and the bearings 2, 4, 6 can be lubricated. As a result, the cutting blade 32 can be stably and smoothly over a long period of time. It can be rotated, and the convenience and safety of the mower A can be improved.

  Therefore, for example, in order to lubricate the drive shaft gear G1 and the main shaft gear G2, grease containing extreme pressure agent (hereinafter referred to as gear lubrication grease) is contained in the predetermined space S surrounding the gears G1 and G2. It is filled (enclosed) so as to have a volume ratio of approximately 70% to 100% with respect to the space volume of the part S. In this case, the gear lubrication grease is a consistency No. specified by the National Lubricating Grease Institute (NLGI). As an example, the grease is composed of lithium soap as a thickener and mineral oil as a base oil.

  Further, for example, as the rotary blade side bearing 2, a sealed ball bearing in which a contact type rubber seal (not shown) is interposed between the inner and outer rings and balls are incorporated between the inner and outer rings as rolling elements is applied. In order to lubricate the rotary blade side bearing 2, as an example, a grease composed of lithium soap as a thickener and mineral oil as a base oil (hereinafter referred to as bearing lubrication grease) is enclosed inside the bearing. ing. In this case, as an example, the rubber seal (not shown) has an outer diameter portion fixed to the outer ring of the rotary blade side bearing 2 and an inner diameter portion (lip portion) formed on the inner ring of the rotary blade side bearing 2. It is positioned so as to be in sliding contact with the seal groove (not shown).

In the rotary blade unit U2 in which the gears G1 and G2 and the bearings 2 and 4 are lubricated in this way, the rotary blade side bearing 2 is only passed through a rubber seal (a seal (not shown) located on the gears G1 and G2 side). And is always in contact with the gear lubrication grease.
Further, when the mower A is in use, the drive shaft gear G1 and the rotary blade side bearing 2 and the main shaft gear G2 and the rotary blade side bearing 2 are arranged vertically with the gears G1 and G2 facing upward. A large amount of grease accumulates on the outer surface (surface on the gears G1, G2 side) of a rubber seal (not shown) located on the gears G1, G2 side by its own weight, and presses the seals. In addition, the outer surface of the rubber seal (not shown) in which the gear lubrication grease is located on the gears G1 and G2 side is also caused by the pressure change in the space S due to the rotation of the main shaft 8 and the vibration due to the rotation of the rotary blade side bearing 2. A large amount is deposited on the (gear G1, G2 side surface), and the seal is pressed.

If the rubber seal (not shown) is continuously pressed by the gear lubrication grease, as a result, the gear lubrication grease is transferred from the sliding contact portion between the lip portion of the seal and the seal groove of the rotary blade side bearing 2 to the rotary blade side. Leakage (intrusion) may occur inside the bearing 2.
In this case, for example, grease having a configuration similar to gear lubrication grease is applied as grease (bearing lubrication grease) sealed in the rotary blade side bearing 2, so that the bearing lubrication grease is mixed with the gear lubrication grease. As a result, it is possible to minimize the quality change or malfunction of the grease.
JP 2004-194521 A JP-A-8-130959

  However, when leakage (penetration) of the gear lubrication grease into the bearing progresses as described above, the amount of grease in the rotary blade side bearing 2 increases from a set value, and stirring and shearing are activated, It may soften. When such softening of the grease occurs, the lip portion of the rubber seal (seal (not shown) located on the cutting blade 32 side) of the rotary blade side bearing 2 and the seal groove (not shown) of the rotary blade side bearing 2 are generated. The grease may leak out of the rotary blade side bearing 2 from a sliding contact portion or an air hole (not shown) provided in the seal. In this case, for example, the leaked grease adheres to the cutting blade 32 (the state of the grease Gb in FIG. 2B), which may deteriorate the rotational accuracy of the cutting blade 32, as well as against vegetation and soil. There is also a risk of adverse effects.

  Further, when the gear lubrication grease continuously leaks (enters) into the rotary blade side bearing 2 and further to the outside of the rotary blade side bearing 2, the drive shaft gear G1 and the main shaft gear G2 become insufficiently lubricated. Since the teeth of the gears G1 and G2 are rubbed against each other and worn, the gears G1 and G2 may not rotate smoothly, and their rotational accuracy may deteriorate.

  As a measure for avoiding such inconvenience, for example, as a gear lubrication grease, the NLGI consistency is No. 3 or No. No. 4 grease, that is, NLGI consistency No. Applying a grease harder than the grease No. 2 to suppress the softening caused by stirring or shearing the grease, the grease is attached to the inner wall of the predetermined space S surrounding the drive shaft gear G1 and the main shaft gear G2. There are measures and measures to reduce the filling amount (filling amount) of the grease.

  However, when the hardness of the gear lubrication grease is increased, the fluidity of the grease decreases and the amount of grease that contributes to the lubrication of the drive shaft gear G1 and the main shaft gear G2 decreases. As a result, the gears G1 and G2 are lubricated. For example, as in the case described above, the teeth of the gears G1 and G2 may be rubbed against each other and worn. On the other hand, when the filling amount (encapsulation amount) of the gear lubrication grease is decreased, the grease does not sufficiently spread into the space S, and as a result, the drive shaft gear G1 and the main shaft gear G2 become insufficiently lubricated, and the same situation occurs. It may become.

  The present invention has been made in order to solve such a problem, and its purpose is to keep the internal pressure at substantially the same pressure as the atmospheric pressure, thereby preventing leakage of grease enclosed inside to the outside, An object of the present invention is to provide a rotating member support unit capable of stably rotating a rotating member with a constant rotation accuracy over a long period of time.

In order to achieve such an object, a rotating member support unit according to the present invention includes a main shaft extending in a predetermined direction, a plurality of rolling bearings that rotatably support the main shaft, and a drive device. In order to transmit the rotational force of the driven drive shaft to the main shaft, at least one set of gears provided on one end side of the drive shaft and the main shaft and meshing with each other, and a rotation attached to the other end side of the main shaft An internal pressure adjusting mechanism is provided that includes a member and a case that accommodates the main shaft, the rolling bearing, and the gear, and that keeps the internal pressure at substantially the same pressure as the atmospheric pressure.
In such a rotating member support unit, as an internal pressure adjusting mechanism, when the internal pressure of the rotating member support unit increases, the internal air of the unit is discharged from the inside of the unit to the outside, and when the internal pressure decreases, the external air of the unit is By allowing the internal pressure of the unit to flow from the outside to the inside of the unit, the internal pressure of the unit is always adjusted to substantially the same pressure as the atmospheric pressure, and an internal pressure adjusting chamber is provided that can collect and accumulate the lubricant sealed inside the unit. It has been. In this case, the internal pressure adjustment chamber has at least one open hole that communicates with the inside of the unit through a communication hole provided in the case, and communicates the inside of the unit with the outside. Are divided into a plurality of compartments, and the interiors of these compartments communicate with each other by air holes penetrating the partition walls.

As an example, the internal pressure adjusting chamber has a divided structure in which one partition is formed in the center by one partition, surrounds the partition, and a plurality of partitions and partitions are alternately arranged outside. The air holes formed in the adjacent partition walls may be arranged so as not to face each other.
Note that a cutting blade for cutting off the vegetation growing on the ground surface from the vicinity of the root can be attached to the main shaft as a rotating member.

  According to the rotating member support unit of the present invention, the internal pressure can always be maintained at substantially the same pressure as the atmospheric pressure. As a result, leakage of the grease sealed inside to the outside can be prevented and the rotating member can be used for a long time. It can be continuously rotated with a constant rotational accuracy.

  Hereinafter, a rotating member support unit according to an embodiment of the present invention will be described with reference to the accompanying drawings. The present invention can be applied as a rotating member support unit mounted on, for example, a mower, a brush cutter and a lawn mower, or an electric tool. That is, the present invention can be applied to a rotating member support unit in which a main shaft extends in a predetermined direction and is installed to support various rotating members that rotate together with the main shaft. A configuration of the rotary blade unit will be described on the assumption that a rotary blade unit used for a mowing machine in which a cutting blade (rotary blade) for cutting off a plant from the base is attached to a main shaft as a rotary member is taken as an example. In this case, the overall configuration of the mower according to the present embodiment is assumed to be the same configuration as that of the conventional mower A (FIG. 2A) described above as an example. Further, the basic configuration of the rotary blade unit according to the present embodiment is the same as the conventional rotary blade unit U2 (FIG. 2B) described above, and therefore the same or similar configuration as the rotary blade unit U2 is described above. Are denoted by the same reference numerals in the drawings, and the description thereof is omitted or simplified.

  FIGS. 1A to 1D show a rotary blade unit U1 (rotary member support unit) of a mower according to an embodiment of the present invention. The rotary blade unit U1 has a predetermined direction. The rotational force of the extended main shaft 8, the plurality of rolling bearings 2 and 4 that rotatably support the main shaft 8, and the driving shaft 38 rotated by the driving device (see the engine 34 (see FIG. 2A)). In order to transmit to the main shaft 8, at least one set of gears G1, G2 provided on one end side (the left end side and the upper end side in FIG. 1A) of the drive shaft 38 and the main shaft 8 and meshing with each other; A rotating member (cutting blade 32) attached to the other end side of the main shaft 8 (lower end side in the figure) is provided.

The main shaft 8, the rolling bearings 2, 4 and the gears G1, G2 are respectively housed in a cylindrical case 40, and the cutting blade 32 is fastened and fixed to the main shaft 8 by a fastening member (screw). It is attached to the outside of the case 40 (the lower side of FIG. 1A).
The main shaft 8 is erected so as to extend in a substantially vertical direction when the mower is in use, whereas the drive shaft 38 has a predetermined inclination angle (with respect to the drive shaft 38). And an angle formed between the main shaft 8 and the main shaft 8 via the drive shaft gear G1 and the main shaft gear G2. The inclination angle is arbitrarily set according to, for example, the usage environment or purpose of use of the mower, and is not particularly limited here. As an example, in the present embodiment, the drive shaft 38 is the main shaft 8. Is inclined at an inclination angle of about 120 ° (about 30 ° with respect to the cutting blade 32 in another way) (FIG. 1A).

  In the configuration shown in FIG. 1A, the rotary blade unit U1 includes, as an example, two rolling bearings (rotary blade side bearing 2 (lower bearing in the figure) and gear side bearing 4 (upper side in the figure). The rotary blade side bearing 2 and the gear side bearing 4 are externally fitted to the main shaft 8 and are internally fitted to the case 40 to rotatably support the main shaft 8. Yes. In this case, as an example, the rotary blade side bearing 2 is positioned between the cutting blade 32 and the gear G2 (main shaft gear to be described later) approximately in the middle of the extending direction of the main shaft 8, in another way. The gear-side bearing 4 is positioned at the end of the main shaft 8 opposite to the cutting blade 32 (the upper end in FIG. 1A).

  In the configuration shown in FIG. 1A, the rotary blade unit U1 includes, as an example, a pair of gears (a drive shaft gear G1 (the right gear in the drawing) and a main shaft gear G2 (the left gear in the drawing). )), The drive shaft gear G1 is externally fitted to the drive shaft 38, and the main shaft gear G2 is externally fitted to the main shaft 8 to mesh with each other. As a result, the drive shaft gear G1 and the main shaft gear G2 change the direction of the rotational force generated by the engine 34 (FIG. 2A) and reduce the speed of the cutting blade attached to the main shaft 8. 32 is rotated to perform a so-called transmission function.

  The type, size, shape, number of teeth, pitch, and the like of the drive shaft gear G1 and the main shaft gear G2 are arbitrarily set according to the size of the drive shaft 38 and the main shaft 8, the positional relationship between the two shafts, and the like. Therefore, there is no particular limitation here. For example, as in the case of the mower according to the present embodiment, the drive shaft 38 and the main shaft 8 are connected at a predetermined inclination angle (for example, about 120 °) (see FIG. 1A). As the drive shaft gear G1 and the main shaft gear G2, bevel gears such as a bevel gear, a helical bevel gear, and a spiral bevel gear may be applied.

  In the present embodiment, the rotary blade unit U1 which is a rotary member support unit is provided with an internal pressure adjusting mechanism for keeping the internal pressure of the rotary blade unit U1 at substantially the same pressure as the atmospheric pressure. In this case, as the internal pressure adjusting mechanism, an internal pressure adjusting chamber 20 is provided that adjusts the internal pressure of the rotary blade unit U1 by discharging the internal air of the rotary blade unit U1 and flowing in the outside air to the rotary blade unit U1. . That is, the internal pressure adjusting chamber 20 discharges the internal air of the rotary blade unit U1 from the inside of the unit U1 to the outside when the internal pressure of the rotary blade unit U1 rises, and reduces the pressure inside the unit U1 to thereby reduce the rotary blade unit U1. The internal pressure of U1 is adjusted to be substantially the same as the atmospheric pressure. On the other hand, when the internal pressure of the rotary blade unit U1 decreases, the internal pressure of the rotary blade unit U1 is increased by allowing the outside air of the rotary blade unit U1 to flow from the outside to the inside of the unit U1 and pressurizing the inside of the unit U1. Adjust so that the pressure is almost the same as the atmospheric pressure. Thereby, the internal pressure adjustment chamber 20 always maintains the internal pressure of the rotary blade unit U1 at substantially the same pressure as the atmospheric pressure.

  The internal pressure adjusting chamber 20 has the inside (hereinafter referred to as the inside of the adjusting chamber) connected to the inside of the rotary blade unit U1 (the drive shaft gear G1 and the main shaft gear G2 in FIG. 1A) by a communication hole 40h provided in the case 40. The structure has a structure having at least one open hole for communicating the inside (space part S) of the rotary blade unit U1 with the outside.

  In the configuration shown in FIGS. 1A to 1D, as an example, the entire outer shape of the internal pressure adjusting chamber 20 is substantially cylindrical, and one side (the upper side of FIG. 1A) of the cylinder is a lid portion. By being closed by 20b, a predetermined cylindrical space is formed in the adjustment chamber, and only one open hole 20k is provided for the peripheral edge 20c. In this way, the internal pressure adjusting chamber 20 communicates the inside of the rotating blade unit U1 communicated with the inside of the adjusting chamber through the communication hole 40h by connecting the inside of the adjusting chamber with the open hole 20k (space portion S). The space portion S can be opened to the outside.

In this case, as an example, the open hole 20k partially has a predetermined shape (such as a semicircle or a rectangle) on one side of the peripheral portion 20c (the side opposite to the lid portion 20b (the lower side in FIG. 1A)). Are formed as notches cut out to a predetermined size.
If the open hole 20k can communicate the inside (space part S) of the rotary blade unit U1 with the outside via the inside of the adjustment chamber (open the space part S to the outside), The form (size, shape, etc.), position and number are not particularly limited. For example, as the open hole 20k, a predetermined through-hole having a circular or rectangular cross-sectional shape may be formed in the peripheral portion 20c of the internal pressure adjusting chamber 20 instead of a notch. Further, not only one open hole 20k but also two or more open holes may be formed. In this case, all the open holes 20k may be formed as notches or through holes having the same shape, or notches or through holes having different shapes. You may comprise the open hole 20k combining a hole.

  The internal pressure adjusting chamber 20 has a structure in which the inside of the adjusting chamber (the above-described cylindrical space) is divided into a plurality of compartments (hereinafter referred to as compartments) by a partition, specifically, a single partition. One compartment is formed in the section, and a divided structure is formed in which a plurality of compartments and partition walls are alternately disposed on the outside so as to surround the compartment. As an example, in the configuration shown in FIGS. 1A to 1D, the adjustment chamber inside of the internal pressure adjustment chamber 20 is concentric with the adjustment chamber inside and is divided into three annular partitions 71 and 72 having different diameters. It is divided into compartments 61, 62, 63.

  In this case, the inside of the internal pressure adjusting chamber 20 is divided by a relatively small-diameter annular partition wall (hereinafter referred to as a first partition wall) 71, and a cylindrical compartment (hereinafter referred to as a first compartment) is formed at the center. 61) is formed, and an annular compartment having a larger diameter than the first compartment 61 is formed on the outside thereof. Further, the large-diameter annular compartment is divided by a relatively large-diameter annular partition wall (hereinafter referred to as a second partition wall) 72, and the first partition chamber 61 and the second partition wall 72 are provided with the second partition wall 72. An annular compartment (hereinafter referred to as a second compartment) 62 having a larger diameter than that of the first compartment 61 is formed, and the second compartment 62 and the peripheral portion 20c of the internal pressure adjusting chamber 20 are arranged between the second compartment 62 and the peripheral portion 20c. An annular compartment (same as the third compartment) 63 having a larger diameter than the compartment 62 is formed.

  In other words, the internal pressure adjusting chamber 20 is separated from the first partition wall 71 and has a structure in which the second partition chamber 62 is concentrically surrounded on the outside of the first partition chamber 61, and is separated from the second partition wall 72. In this state, the third compartment 63 is concentrically surrounded on the outside of the second compartment 62.

  Further, in the internal pressure adjusting chamber 20, these compartments 61, 62, 63 are communicated with each other by air holes 71 h, 72 h penetrating the partition walls 71, 72. Specifically, the inside of the first compartment 61 and the inside of the second compartment 62 are communicated with each other by an air hole 71 h formed in the first partition wall 71. The interior of the third compartment 63 is in communication with each other by an air hole 72 h formed in the second partition wall 72. Thus, the first compartment 61, the second compartment 62, and the third compartment 63 are connected to each other through the air holes 71h of the first partition 71 and the air holes 72h of the second partition 72, respectively. It can be.

  In this case, the shape (size, shape, etc.), position, and number of the air holes 71h, 72h are not particularly limited as long as the interiors of the compartments 61, 62, 63 can be communicated with each other. As an example, in the present embodiment, one side (the upper side or the lower side of FIGS. 1A and 1D) of the first partition wall 71 and the second partition wall 72 is partially formed in a predetermined shape (semicircle, rectangle, etc. ), A case is assumed in which air holes 71h and 72h are formed as notches cut into a predetermined size. However, instead of such a notch, for example, as the air holes 71h and 72h, the first partition wall 71 is arranged from the inner peripheral side (first compartment 61 side) to the outer peripheral side (second compartment 62 side), and A through-hole is formed through the second partition wall 72 from the inner circumference side (second compartment 62 side) to the outer circumference side (third compartment 63 side) in a circular shape or a rectangular shape having a predetermined cross section. May be.

  In the configuration shown in FIGS. 1B and 1C, as an example, two first holes 71h and 72h are provided in each of the first partition wall 71 and the second partition wall 72, and the first partition wall 71h is provided. The two air holes 71 h of 71 are arranged with a phase difference of 180 ° with respect to the center of the first partition wall 71 (that is, on both ends of the diameter), and the two air holes of the second partition wall 72 72h is also arranged with a phase difference of 180 ° with respect to the center of the second partition wall 72 (that is, on both ends of the diameter). In this case, the air holes 71h of the first partition wall 71 and the air holes 72h of the second partition wall 72 are alternately opposed to each other with a 90 ° phase difference with respect to the centers of the partition walls 71 and 72. It is arranged without. Further, the two air holes 72h of the second partition wall 72 have a predetermined phase difference from the open hole 20k and are arranged so as not to face each other. That is, the air holes 71h, the air holes 72h, and the open holes 20k are arranged so as not to face each other.

By arranging the four air holes 71h and 72h in this way, the internal air of the internal pressure adjusting chamber 20 can be smoothly flowed into the respective compartments 61, 62 and 63, and the internal pressure adjusting chamber 20 can be externally supplied. It is possible to effectively prevent the intrusion of foreign matters (for example, cut wood scraps, sludge, dust, etc.) into the interior. That is, for example, even if a foreign matter enters the third compartment 63 from the outside through the opening hole 20k to the internal pressure adjusting chamber 20, the foreign matter is released into the opening hole 20k, the air hole 71h, and the air. Since none of the holes 72h face each other, the inside of the rotary blade unit U1 communicated with the first compartment 61 from the third compartment 63 to the second compartment 62 and the first compartment 61 and further through the communication hole 40h ( The space portion S) cannot be easily penetrated, and the entry of such foreign matter can be effectively prevented.
As a result, early damage to the drive shaft gear G1 and the main shaft gear G2 due to the entry of foreign matter into the interior (space S) of the rotary blade unit U1, and the rotary blade side bearing 2, the gear side bearing 4, and the drive shaft bearing 6 Early damage can be effectively prevented.

In the present embodiment, two air holes 71h and 72h are provided for each of the first partition wall 71 and the second partition wall 72, but one each for the first partition wall 71 and the second partition wall 72. Air holes 71h and 72h may be provided one by one, or three or more air holes 71h and 72h may be provided, respectively. Even in this case, the air hole 71h of the first partition wall 71 and the air hole 72h of the second partition wall 72 are arranged with a predetermined phase difference so as not to face each other. It is preferable to provide a predetermined phase difference so that 72h does not face the open hole 40k.
Further, the air holes 71h and 72h may be all the same size and the same shape of notches and through holes, or each partition wall 71 and 72 or each partition wall 71 and 72 may have different sizes and different shapes. The air holes 71h and 72h may be formed by combining the through holes.

Here, the size, shape, and number of the internal pressure adjusting chamber 20, and the sizes, shapes, and numbers of the compartments 61, 62, 63 and the partition walls 71, 72 are, for example, the size of the rotary blade unit U1. Since it is arbitrarily set according to this, there is no particular limitation.
As an example, in the configuration shown in FIGS. 1A to 1D, the compartments 61, 62, 63 and the partition walls 71, 72 are formed in a circular shape (cylindrical shape and cylindrical shape). In addition, for example, an elliptical shape (elliptical cylindrical shape or elliptical columnar shape), a rectangular shape (rectangular cylindrical shape or rectangular columnar shape), a polygonal shape (polygonal cylindrical shape or polygonal columnar shape), or the like may be formed. Further, the compartments 61, 62, 63 and the partition walls 71, 72 may be formed by combining these various shapes.

Further, in the configuration shown in FIG. 1A, only one internal pressure adjusting chamber 20 is provided outside the top portion (upper portion in the figure) 40u of the case 40. In this case, the peripheral portion 20c of the internal pressure adjusting chamber 20 has a circumferential end at one end thereof (an end opposite to the lid 20b (lower end in FIGS. 1A and 1D)). Along with this, an engaging portion (hereinafter referred to as a fixed claw) 20j for attaching the internal pressure adjusting chamber 20 to the case 40 is provided. The fixed pawl 20j is continuous to one end of the peripheral edge 20c (the lower end of FIGS. 1A and 1D) and is substantially perpendicular to the entire circumference except for the open hole 20k portion of the end. At a predetermined height (distance in the vertical direction in the figure), a predetermined distance protrudes in the direction of diameter reduction of the peripheral edge portion 20c. On the other hand, the case 40 has a concave groove (hereinafter referred to as an engagement groove) 40d for engaging the entire fixed pawl 20j of the internal pressure adjusting chamber 20 with the outer peripheral portion in the rotational direction of the main shaft 8 in the circumferential direction. And the same size (length, width (height) and depth (distance)) as the fixed pawl 20j.
Thus, the fixed pawl 20j is engaged with the engagement groove 40d of the case 40, and is pushed into the engagement groove 40d until the inner peripheral surface of the peripheral edge portion 20c is substantially flush with the outer peripheral surface of the case 40. The internal pressure adjusting chamber 20 can be easily attached (fitted and fixed) to the case 40.

Note that the method of attaching the internal pressure adjusting chamber 20 is not limited to such fitting and fixing, and in addition to this, for example, the inner pressure adjusting chamber 20 may be bonded and fixed by bonding, welding, or the like, or a fastening member (screw or pin). May be fastened and fixed. Further, the internal pressure adjusting chamber 20 may be attached to the case 40 by combining these various methods.
In the configuration shown in FIG. 1A, as an example, the internal pressure adjusting chamber 20 is provided outside the top 40 u of the case 40, but the position is not limited to this, and for example, the side surface of the case 40 It may be provided externally in a portion (horizontal direction with respect to the extending direction of the main shaft 8 (left and right direction in the figure, for example, left side portion in the figure)).

  Here, the internal pressure adjusting chamber 20 is in a state in which the fixed pawl 20j is engaged with the engaging groove 40d of the case 40 in this way (see FIG. 1 (FIG. 1)). The heights of the partition walls 71 and 72 (FIGS. 1A and 1D) are such that the lower ends of a) and (D) are in close contact with the outside of the top 40u of the case 40 (upper side of FIG. 1A). The distance in the vertical direction d) is set to a predetermined dimension. In this case, one end of the first partition 71 and the second partition 72 (the lower end in FIGS. 1A and 1D) and the top 40u of the case 40 are bonded, welded, or the like, for example. It is good also as a structure each joined and fixed by.

  Similarly, the internal pressure adjusting chamber 20 is in a state where the fixed pawl 20j is engaged with the engaging groove 40d, on the outside side of the communication hole 40h provided in the top 40u of the case 40 (the upper side of FIG. 1A). ), The size of the internal pressure adjusting chamber 20 and the size (diameter) of the first compartment 61 are set to predetermined dimensions so that the opening ho is opened in the first compartment 61. And positioned with respect to the case 40. Thereby, the 1st compartment 61 and the inside (space part S) of the rotary blade unit U1 can be connected by the communication hole 40h, Furthermore, the 2nd compartment 62 and the air via the air holes 71 and 72 and The third compartment 63 can be communicated with the space S. That is, the inside of the internal pressure adjusting chamber 20 and the inside of the rotary blade unit U1 (space part S) can be communicated with each other, and the space part S can be opened to the outside through the opening hole 20k. can do.

  In this case, the top portion 40u of the case 40 is provided from the inside to the outside of the top portion 40u (from the gear-side bearing 4 side to the first compartment 61 side (from the lower side to the upper side in FIG. 1 (a)). ) Is provided, and the communication hole 40h is large if it is possible to communicate the inside of the internal pressure adjusting chamber 20 and the inside of the rotary blade unit U1 (space S). The shape, number, and the like can be arbitrarily set according to the size of the internal pressure adjusting chamber 20, the size of the rotary blade unit U1, and the like.

  As an example, in the configuration shown in FIG. 1A, when only one communication hole 40h is formed as a through-hole that penetrates from the inside to the outside of the top 40u of the case 40 in a cylindrical shape having a diameter of 1 mm. Is assumed. The formation position of the communication hole 40h is not particularly limited as long as the inside of the internal pressure adjusting chamber 20 and the inside of the rotary blade unit U1 (space part S) can be communicated with each other, but as described above, the opening ho. Is preferably formed on the top 40 u of the case 40 so as to be opened in the first compartment 61 of the internal pressure adjusting chamber 20. Furthermore, although two or more communication holes 40h may be formed, even in this case, these communication holes 40h similarly open the opening ho in the first compartment 61 of the internal pressure adjusting chamber 20. It is desirable to form as follows.

In addition, although it did not mention in particular about the raw material of the internal pressure adjustment chamber 20, the internal pressure adjustment chamber 20 should just be comprised with various elastic materials, such as various resin materials, such as polyethylene, and a nitrile rubber, for example. Accordingly, the fixed pawl 20j can be elastically deformed to expand the diameter by only applying a slight force to the fixed pawl 20j in the diameter increasing direction, and thereafter the force in the diameter expanding direction is released. Thus, the fixed pawl 20j returns to the original state before the diameter expansion, and the internal pressure adjusting chamber 20 can be easily fitted and fixed to the case 40. Similarly, it is easy to remove, and, for example, maintenance work performed by attaching / detaching the internal pressure adjusting chamber 20 becomes easy.
However, considering the temperature rise of the rotary blade unit U1 accompanying the rotation of the cutting blade 32, the internal pressure adjusting chamber 20 is a material that does not deform or deteriorate even at high temperatures (eg, 110 ° C. or higher) (for example, It is preferable to use a resin material or an elastic material having a melting point of 110 ° C. or higher. Further, in consideration of lubrication for the rotary blade unit U1, it is preferable to use a resin material or an elastic material that does not cause deterioration of the gear lubrication grease described later.

  Thus, by providing the internal pressure adjusting chamber 20 with respect to the rotary blade unit U1, the inside (space portion S) of the rotary blade unit U1 and the adjustment chamber inside the internal pressure adjusting chamber 20 are communicated with each other through the communication hole 40h. In normal times, both the internal pressure of the rotary blade unit U1 and the internal pressure of the internal pressure adjusting chamber 20 are maintained at a substantially constant pressure (substantially the same pressure as the atmospheric pressure). Specifically, the internal pressure of the rotary blade unit U1 and the internal pressures of the first compartment 61, the second compartment 62, and the third compartment 63 communicated with each other through the air holes 71h and 72h are substantially the same as the atmospheric pressure. The pressure is maintained.

From this state, for example, when the main shaft 8 rotates, the inside of the rotary blade unit U1 is pressurized, the internal pressure of the rotary blade unit U1 rises, and the internal pressure (specifically, the first interval of the internal pressure adjusting chamber 20). The internal pressure of the rotary blade unit U1 (hereinafter, this internal air will be referred to as the unit internal air) is pressed and passes through the communication hole 40h to the inside of the first compartment 61. Is flowed into. At that time, the inside air in the first compartment 61 (hereinafter, this inside air is referred to as the first compartment air) is pressed by the unit inside air that has flowed into the first compartment 61 and passes through the air holes 71h of the first partition 71. It flows into the inside of the second compartment 62 through.
As a result, the inside air in the second compartment 62 (hereinafter, this inside air is referred to as the second compartment air) is pressed by the first compartment air flowing into the second compartment 62, and the air in the second partition 72 It flows into the third compartment 63 through the hole 72h. Further, the inside air of the third compartment 63 (hereinafter, this inside air is referred to as the third compartment air) is pressed by the second compartment air flowing into the third compartment 63, and the opening hole of the peripheral edge portion 20c. It is discharged to the outside of the internal pressure adjusting chamber 20 through 20k.

  As a result, the unit internal air that has flowed into the internal pressure adjusting chamber 20 (specifically, the first compartment 61) from the rotary blade unit U1 by the amount corresponding to the amount of the inflow is the first compartment air and the second compartment air. Then, the air can be discharged to the outside of the internal pressure adjusting chamber 20, that is, to the outside of the rotary blade unit U1 as the third compartment air. As a result, the increase in internal pressure of the rotary blade unit U1 is offset by discharging the unit internal air (specifically, the third compartment air) to the outside of the rotary blade unit U1, and the internal pressure of the rotary blade unit U1 increases. In addition to being able to suppress the continuation, the internal pressure can always be kept at a substantially constant pressure (specifically, adjusted to substantially the same pressure as atmospheric pressure).

On the other hand, from the state in which the internal pressure of the rotary blade unit U1 and the internal pressure of the internal pressure adjusting chamber 20 are maintained at a substantially constant pressure, for example, when the spindle 8 stops, the inside of the rotary blade unit U1 is decompressed, and the rotary blade unit When the internal pressure of U1 decreases and a pressure difference occurs between the internal pressure of the internal pressure adjusting chamber 20 (specifically, the internal pressure of the first compartment 61), the air in the first compartment is moved into the rotary blade unit U1. It is sucked and flows out into the rotary blade unit U1 through the communication hole 40h. At that time, the second compartment air flows into the first compartment 61 from the second compartment 62 through the air holes 71h of the first partition wall 71 by an amount corresponding to the outflowing first compartment air.
Thus, the third compartment air flows from the third compartment 63 into the second compartment 62 through the air holes 72h of the second partition wall 72 by an amount corresponding to the outflowing second compartment air, and Outside air flows into the third compartment 63 from the outside of the internal pressure regulation chamber 20 through the open hole 20k of the peripheral edge portion 20c by an amount corresponding to the third compartment air that has flowed out.

  As a result, the internal pressure of the first compartment air that has flowed out from the internal pressure adjustment chamber 20 to the rotary blade unit U1 is adjusted as the external air from the outside of the internal pressure adjustment chamber 20, that is, from the outside of the rotary blade unit U1, by an amount corresponding to the outflow amount. It can be made to flow into the chamber 20 (specifically, the third compartment 63). As a result, the decrease in the internal pressure of the rotary blade unit U1 is offset by flowing outside air from the outside of the rotary blade unit U1 into the internal pressure adjusting chamber 20 (specifically, the third compartment 63). The internal pressure of U1 can be prevented from continuing to decrease, and the internal pressure can always be maintained at a substantially constant pressure (specifically, adjusted to substantially the same pressure as the atmospheric pressure).

  In addition, when the inside of the rotary blade unit U1 shifts from the pressurized state to the depressurized state, and also when the inside of the rotary blade unit U1 shifts from the depressurized state to the pressurized state, the inside air (the first compartment air, Similarly, the internal pressure of the rotary blade unit U1 is always maintained at a substantially constant pressure by the inflow / outflow of the second compartment air and the third compartment air) and the inflow of outside air of the rotary blade unit U1 (specifically, atmospheric pressure And can be adjusted to substantially the same pressure).

  In the rotary blade unit U1 configured as described above, as in the case of the conventional mower A described above, in order to rotate the cutting blade 32 stably and smoothly over a long period of time, the drive shaft gear G1 and the main shaft For the purpose of reducing friction and wear at the portions where the teeth of the gear G2 are in contact with each other, preventing seizure of the rotary blade side bearing 2, the gear side bearing 4 and the drive shaft bearing 6 and extending the fatigue life, etc. , G2, and the bearings 2, 4, and 6 are lubricated.

In the present embodiment, as an example, the American Grease Association (NLGI) is provided inside the rotary blade unit U1 (a predetermined space S surrounding the drive shaft gear G1 and the main shaft gear G2).
Consistency No. specified by the Lubricating Grease Institute) 2 (Consistency No. 2) grease (hereinafter referred to as gear lubrication grease) is filled (enclosed) so that the volume ratio of the space S is approximately 70% to 100%. . Similarly, the NLGI consistency No. is also applied to the inside of the rolling bearings (the rotary blade side bearing 2, the gear side bearing 4, and the drive shaft bearing 6). Two greases (hereinafter referred to as bearing lubrication greases) are filled (enclosed) so as to have a volume ratio of approximately 25% with respect to the space volume in each of the bearings 2, 4, 6.

  In addition, since the component structure of a gear lubrication grease and a bearing lubrication grease is arbitrarily set, for example according to the use purpose of the rotary blade unit U1, use conditions, etc., it does not specifically limit here. For example, the gear lubrication grease and the bearing lubrication grease may be configured, for example, as a thickener with lithium soap and a base oil as mineral oil. In this case, an extreme pressure agent may be added as an additive to the thickener and the base oil.

Here, the use state of the mower according to the present embodiment, that is, the state change of the gear lubricating grease during the operation of the rotary blade unit U1 will be described below.
The gear-lubricating grease is continuously stirred and sheared in the space S by its own weight, and the vibration caused by the rotation of the main shaft 8 and the main shaft gear G2 while the driving shaft 38 and the driving shaft gear G1 rotate. The gear lubricating grease that has been repeatedly stirred and sheared as described above rises in temperature, and is softened and thermally expanded.

  At this time, since the pressure (internal pressure) in the rotary blade unit U1 (space S) increases, the pressure between the internal pressure and the internal pressure in the internal pressure adjustment chamber 20 (specifically, the internal pressure in the first compartment 61). A pressure difference is generated. In this case, the pressing force toward the outside of the rotary blade unit U1 against the internal air of the rotary blade unit U1 and the gear lubricating grease sealed in the space portion S, specifically, the inner wall S1 of the space portion S and the rotary blade A pressing force is applied to the side bearing 2.

  In the present embodiment, since the internal pressure adjusting chamber 20 is provided in the rotary blade unit U1, even if the pressing force as described above is applied to the gear lubricating grease sealed in the space S, The gear lubricating grease can be collected by flowing into the internal pressure adjusting chamber 20 (specifically, inside the first compartment 61) through the communication hole 40h together with the unit air. Thereby, it is possible to prevent the gear lubricating grease from being continuously pressed against the rotary blade side bearing 2 and leaking (invading) into the inside thereof. The gear lubricating grease collected in the internal pressure adjusting chamber 20 (the first compartment 61) is not stirred and sheared, its temperature is lowered, and is hardened by the action of a thickener to become semi-solid. To do.

  In this case, the unit internal air that has flowed into the first compartment 61 flows into the second compartment 62 and the third compartment 63 as described above, and then outside the internal pressure adjusting chamber 20 through the open hole 20k, that is, The air is discharged outside the rotary blade unit U1 as the third compartment air. On the other hand, the gear lubricating grease collected and semi-solidified in the first compartment 61 adheres to the inner surface of the first compartment 61. The gear lubricating grease adhering to the inner surface of the first compartment 61 is heat-exchanged with the second compartment 62 (specifically, the heat is released to the second compartment 62) and cooled. This hardens early and is fixed to the inner surface of the first compartment 61.

Thus, since the gear lubricating grease collected by flowing into the first compartment 61 is hardened and fixed at an early stage, the gear lubricating grease is not drawn into the communication hole 40h. The so-called stopper does not block the communication hole 40h. Further, it effectively prevents the gear lubricating grease collected by flowing into the first compartment 61 from passing through the communication hole 40h again to harden and become a plug. be able to.
The gear lubrication grease collected in the first compartment 61 is hardened and fixed at an early stage so that the gear lubrication grease passes through the air holes 71h of the first partition 71 to the inside of the second compartment 62. Furthermore, it is possible to effectively prevent the fluid from flowing through the air hole 72h of the second partition wall 72 to the third compartment 63.

For this reason, for example, the internal pressure of the rotary blade unit U1 (space portion S) is reduced by stopping the main shaft 8, and the internal pressure and the internal pressure of the internal pressure adjusting chamber 20 (specifically, the internal pressure of the first compartment 61) are reduced. Even when a pressure difference occurs between them, only the first compartment air can flow out into the rotary blade unit U1 through the communication hole 40h. Then, the internal air (specifically, the first compartment air) that has flowed out of the internal pressure adjustment chamber 20 (specifically, the first compartment 61) into the rotary blade unit U1 is transferred to the outside of the internal pressure adjustment chamber 20, that is, the rotation. It can be allowed to flow from the outside of the blade unit U1 into the inside of the internal pressure adjusting chamber 20 (specifically, the third compartment 63) as outside air. Therefore, the decrease in the internal pressure of the rotary blade unit U1 is offset by flowing outside air from the outside of the rotary blade unit U1 into the internal pressure adjusting chamber 20 (specifically, the third compartment 63), and the rotary blade unit U1. It is possible to prevent the internal pressure from continuing to decrease, and to keep the internal pressure at a substantially constant pressure (specifically, to adjust it to substantially the same pressure as the atmospheric pressure).
As a result, the gear lubrication grease is not continuously pressed against the rotary blade side bearing 2, and leakage (penetration) of the gear lubrication grease into the rotary blade side bearing 2 can be effectively prevented.

  As described above, according to the rotary blade unit U1 according to the present embodiment, the grease (gear lubrication grease and bearing lubrication grease) sealed in the interior (space portion S) leaks into the rotary blade side bearing 2 ( Intrusion), and further, leakage to the outside of the rotary blade unit U1 can be prevented. Thereby, the lubrication state of the rotary blade unit U1 is maintained well, and the cutting blade 32, which is a rotary member, can be stably rotated with a constant rotational accuracy over a long period of time.

  In the above-described embodiment, the configurations of the rotary blade side bearing 2 and the gear side bearing 4 that rotatably support the main shaft 8 are not particularly mentioned. In consideration of the fluidity of the inside air of U1 and prevention of leakage of the gear lubrication grease and the bearing lubrication grease, the following configuration is preferable.

  The gear-side bearing 4 adjacent to the internal pressure adjusting chamber 20 has a so-called open type bearing structure in which a sealing member (contact type seal, non-contact type seal or shield, etc.) for sealing the inside is not provided. That's fine. As a result, the inside air of the rotary blade unit U1 can smoothly pass through the gear side bearing 4, and between the internal pressure adjusting chamber 20 (specifically, the first compartment 61) via the communication hole 40h. The inside air can be smoothly flowed in and out. As a result, the internal pressure of the rotary blade unit U1 can always be maintained at a substantially constant pressure (specifically, adjusted to substantially the same pressure as the atmospheric pressure), and the gear lubrication grease can be continuously pressed against the rotary blade side bearing 2. Therefore, leakage (penetration) of the gear lubricating grease into the rotary blade side bearing 2 can be effectively prevented.

  Further, the rotary blade side bearing 2 in the vicinity of the cutting blade 32 has the drive shaft gear G1 and the main shaft gear G2 side (upper side of FIG. 1A) in an open state where no sealing member is provided, and the cutting blade 32 side ( What is necessary is just to set it as the bearing structure which provided the sealing member (not shown) in FIG. As a result, gear lubrication grease leaks (enters) into the rotary blade side bearing 2, the amount of bearing lubrication grease in the rotary blade side bearing 2 increases from the set value, and stirring and shearing are activated. Even when the grease is softened, leakage of the grease to the outside of the bearing can be effectively prevented. However, a sealing member is provided not only on the cutting blade 32 side (lower side in FIG. 1 (a)) but also on the drive shaft gear G1 and main shaft gear G2 side (upper side in FIG. 1 (a)), so that hermeticity (airtightness) is provided. In addition, the bearing structure may be further improved in liquid tightness.

  In addition, as a sealing member provided in the rotary blade side bearing 2, a non-contact type seal (for example, a whole or a part of a metal core is connected with various elastic materials (for example, resin materials such as rubber and plastic). Etc.) and non-contact type shields (for example, shields pressed from thin metal plates such as stainless steel plates and iron plates) may be applied. It is preferable to apply a seal.

  As an example, a contact-type seal (not shown) as a sealing member is formed by using a variety of elastic materials (for example, rubber) as a part of an annular cored bar formed by pressing or the like such that a cross-section of a steel plate is L-shaped. Or a resin material such as plastic). In this case, it is preferable that the seal is formed with one or a plurality of seal lips made of such an elastic material. In addition, when connecting a metal core and various elastic materials, as a connection method, various methods, such as adhesion, caulking, coating, and injection molding, can be arbitrarily selected and used.

It is a diagram showing a configuration example of a rotary blade unit according to an embodiment of the present invention, (a) is a cross-sectional view of a state in which an internal pressure adjustment chamber is attached, (b) is a top plan view of the internal pressure adjustment chamber, (c) is a cross-sectional view of the internal pressure adjusting chamber. (d) is a longitudinal sectional view of the internal pressure adjusting chamber. It is a figure which shows the structural example of the conventional mower, Comprising: (a) is a perspective view which shows the whole structure, (b) is sectional drawing of a rotary blade unit.

Explanation of symbols

2 Rotary blade side bearing 4 Gear side bearing 8 Main shaft 20 Internal pressure adjustment chamber 20b Lid portion 20c Peripheral portion 20k Open hole 32 Cutting blade 34 Engine 38 Drive shaft 40 Case 40h Communication hole 61 First compartment 62 Second compartment 63 Third Partition 71 First partition 71h, 72h Air hole 72 Second partition G1 Drive shaft gear G2 Main shaft gear U1 Rotary blade unit

Claims (3)

A main shaft extending in a predetermined direction, a plurality of rolling bearings rotatably supporting the main shaft, and a driving shaft for transmitting the rotational force of the driving shaft rotated by the driving device to the main shaft; At least one set of gears provided on one end side of the main shaft and meshing with each other, a rotating member attached to the other end side of the main shaft, and a case for housing the main shaft, the rolling bearing and the gear, A rotating member support unit provided with an internal pressure adjusting mechanism for always maintaining substantially the same pressure as atmospheric pressure,
As an internal pressure adjustment mechanism, when the internal pressure of the rotating member support unit increases, the internal air of the unit is discharged from the inside of the unit to the outside, and when the internal pressure decreases, the external air of the unit flows from the outside of the unit to the inside. By adjusting the internal pressure, the internal pressure of the unit is always adjusted to substantially the same pressure as the atmospheric pressure, and an internal pressure adjusting chamber capable of collecting and storing the lubricant enclosed in the unit is provided. The chamber communicates with the interior of the unit through a communication hole provided in the case, and has at least one open hole that communicates the interior of the unit with the outside. The rotating member support unit is divided, and the interiors of these compartments communicate with each other by an air hole penetrating the partition wall. Door.   The internal pressure adjusting chamber has a divided structure in which one partition is formed in the center by one partition, surrounds the partition, and a plurality of partitions and partitions are alternately arranged outside. The rotating member support unit according to claim 1, wherein the air holes formed in the partition wall are arranged so as not to face each other.   The rotating member support unit according to claim 1 or 2, wherein a cutting blade for cutting off the vegetation growing on the ground surface from near the root is attached to the main shaft.

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