JP5468979B2 - Rammer centrifugal clutch - Google Patents

Description

  The present invention relates to a centrifugal clutch mounted on an engine working machine, and more particularly, to a centrifugal clutch dedicated to a rammer that generates large vibrations and impacts during operation.

  There are various types of centrifugal clutches mounted on various engine working machines. As a typical example, one end side (base end side) of a clutch shoe formed in an arc shape is pivoted so as to be rotatable with respect to the hub, and the other end side (free end side) is a coil spring. When the rotational speed of the drive shaft side part (hub and clutch shoe) reaches a predetermined value while being urged radially inward, the free end side of the clutch shoe is rotated outward by centrifugal force, and the inside of the clutch drum There is a centrifugal clutch configured so that the rotational driving force of the driving shaft is transmitted to the clutch drum (driven shaft side) by the friction force.

  This type of centrifugal clutch is widely used in various engine working machines such as mowers and chainsaws. However, this type of centrifugal clutch is not suitable for work machines that generate large vibrations or shocks during operation, such as rammer, and currently this type of centrifugal clutch is not applied to rammer. Since the Rammer aircraft is subjected to a large load due to vibration and shock, if there is a mechanically movable part (for example, a pivoted part of the clutch shoe) on the centrifugal clutch that is installed, it will be easily damaged and sufficient If the clutch shoe has a large movement range (movement range from the non-transmission state of the driving force to the transmission state), the clutch shoe will be exposed to a shock when subjected to an impact. This is because the driving force cannot be properly transmitted.

  Therefore, the rammer has no mechanical moving parts, the engagement state between the respective components is simple, and a centrifugal clutch in which the movement range of each component is extremely small, for example, the drive shaft side portion is shown in FIG. A centrifugal clutch exclusively for rammers with the structure shown is used.

  The drive shaft side portion of the centrifugal clutch in FIG. 5 is composed of one hub 21, four clutch shoes 22, two ring-shaped springs 23, and two side plates 24. The hub 21 is bundled in a state of being urged inward by ring-shaped springs 23 that are annularly arranged around the hub 21 and attached to both side surfaces. Then, in a combined state as shown in FIG. 5, the clutch shoe 22 is mounted inside a clutch drum (not shown), the drive shaft rotates, and when the rotational speed reaches a predetermined value, The outer circumferential surface of the arcuate lining 22a attached to the outermost circumferential side of each clutch shoe 22 contacts the inner circumferential surface of the clutch drum and spreads against the urging force of the ring-shaped spring 23. The rotational driving force of the drive shaft is transmitted to the clutch drum (driven shaft side) by the force.

  In the drive shaft side portion of the centrifugal clutch, for example, the diameter of the clutch shoe 22 in a bundled state (when not rotating) is set to 80.5 mm, and the inner diameter is 81 mm, which is attached to the inside of the clutch drum. . In this case, the gap between the outer peripheral surface of the lining 22a of the clutch shoe 22 and the inner peripheral surface of the clutch drum is 0.25 mm when not rotating, and the moving range of the clutch shoe 22 becomes extremely small.

JP 2007-162892 A

  Thus, the centrifugal clutch of FIG. 5 has no mechanical movable part, the engagement state between each component is simple, and the movement range of each component is extremely small. Compared with a centrifugal clutch of the type in which the free end side of the clutch shoe rotates around the pivot point on the base end side, it can be expected to have extremely high durability.

  However, when the centrifugal clutch of FIG. 5 is mounted on a rammer, the ring-shaped spring 23 may be broken if the rammer is operated for about 10 hours. The clutch shoe, hub, and side plate have a durability of several hundred hours or longer and are longer than the life of the rammer's fuselage. Or, although there is almost no need for repair, when the ring-shaped spring 23 is broken, it is of course necessary to replace it with a new one.

  That is, the centrifugal clutch of FIG. 5 has a very high durability as a whole, but maintenance of the ring-shaped spring 23 is required with 10 hours as a guideline. From the viewpoint of maintenance, this centrifugal clutch Durability will ultimately depend on the durability of the ring spring.

  The durability of the ring-shaped spring of 10 hours is far higher than when a centrifugal clutch of the type in which the free end of the clutch shoe rotates is applied to the rammer. Can improve the long-lasting and highly durable centrifugal clutch for rammer. An object of the present invention is to solve the above-described problems in the prior art and to provide a centrifugal clutch having extremely high durability.

  In the centrifugal clutch for rammer according to the present invention, the drive shaft side portion is a hub, a plurality of clutch shoes arranged annularly around the hub, and the clutch shoes are bound and urged inward. A ring-shaped spring and a side plate that restricts the lateral movement of the clutch shoe. The hub has a constant lateral width and a plurality of bosses projecting radially outward, or extending in the radial direction. The clutch shoe has a fan-shaped basic shape, an arc-shaped lining is attached to the outer peripheral side, and arc-shaped concave grooves concentric with the arc of the lining are formed on both side surfaces. In the center portion of the clutch shoe in the radial direction, a notch corresponding to the shape of the boss formed on the hub or a notch formed on the hub is formed. One of the bosses having a constant lateral width and projecting inward in the radial direction is formed, and the hub and the clutch shoe are formed on the other in a notch formed on one of them. The clutch shoes are combined so that they can move in the radial direction by entering the bosses, and further, in the periphery of the opening peripheral edge of the concave groove on the facing surface of the adjacent clutch shoe, a predetermined amount inside the facing surface. By forming a step portion having a concave shape, the separation dimension between the opening peripheral portions of adjacent clutch shoes is larger than the separation dimension between the opposing surfaces.

  Instead of forming the stepped portion on the opposing surface of the clutch shoe, the opening peripheral portion may be positioned on the inner side of the opposing surface by chamfering the opening peripheral portion of the groove. . Moreover, while forming a level | step difference part, you may make it chamfer with respect to the opening peripheral part of a groove.

  Further, when the distance between the opening peripheral portions of the concave grooves of the adjacent clutch shoes is S and the element wire diameter of the ring spring is d, the value of S / d is in the range of 2.0 to 3.6. It is preferable to set the dimensions so that

  The centrifugal clutch for rammer according to the present invention can extend the life of the ring-shaped spring for binding the clutch shoe, and as a result, the durability can be dramatically improved compared to the conventional centrifugal clutch for rammer. it can.

FIG. 1 is a side view of a drive shaft side portion of a centrifugal clutch for rammer according to a first embodiment of the present invention. 2 is a cross-sectional view of the drive shaft side portion of the centrifugal clutch for rammer shown in FIG. 1 taken along line xx. FIG. 3 is a perspective view of the clutch shoe 2 shown in FIG. FIG. 4 is a perspective view of the clutch shoe 2 of the centrifugal clutch for rammer according to the second embodiment of the present invention. These are the side views of the drive-shaft side part of the conventional centrifugal clutch for Rammer. These are the figures which show the state which generate | occur | produced between the clutch shoes 22 which adjoin the conventional centrifugal clutch for rammers.

  Hereinafter, embodiments of the “rammer centrifugal clutch” of the present invention will be described. FIG. 1 is a side view of a drive shaft side portion of the centrifugal clutch for rammer according to the first embodiment, and FIG. 2 is a cross-sectional view thereof (cross-sectional view taken along line xx). First, the schematic configuration will be described. As shown in the figure, the drive shaft side portion of the centrifugal clutch includes one hub 1, four clutch shoes 2, two ring-shaped springs 3, and two side plates. 4.

  The four clutch shoes 2 are annularly arranged around the hub 1 around the hub 1 and are bound in a state of being urged inward by ring-shaped springs 3 attached to both side surfaces. 1 and FIG. 2, in the combined state, mounted inside the clutch drum (not shown), the drive shaft rotates, and when the rotational speed reaches a predetermined magnitude or more, each centrifugal force causes The clutch shoe 2 expands outwardly against the urging force of the ring-shaped spring 3, and the outer peripheral surface (lining 2a) of each clutch shoe 2 comes into contact with the inner peripheral surface of the clutch drum. Is transmitted to the clutch drum (driven shaft side).

  Next, details of each component will be described. In the present embodiment, the hub 1 has a thickness of 16 mm, and a shaft hole 1a (diameter: 15 mm) through which the drive shaft is inserted is formed at the center. Further, the four bosses 1b are formed radially at equal intervals (that is, projecting outward in the radial direction). Each boss 1b has a constant width dimension from the base end side to the tip end side.

  Each of the clutch shoes 2 has a fan shape whose basic shape is 90 °, and has a shape in which a disk-shaped member is divided into four parts. An arc-shaped lining 2 a is attached to the outer peripheral side of the clutch shoe 2. As shown in FIGS. 2 and 3 (a perspective view of the clutch shoe 2), concave grooves 2b concentric with the arc of the lining 2a are formed on both side surfaces of the clutch shoe 2, respectively. Further, a notch 2 c corresponding to the shape of the boss 1 b of the hub 1 is formed in the center portion on the radially inner side of the clutch shoe 2.

  The portion on the radially inner side of the groove 2b of the clutch shoe 2 is set to the same thickness dimension (16mm) as the hub 1, and the outer peripheral portion including the lining 2a is slightly thicker (18mm). Is set to The diameter of the clutch shoe 2 bound by the ring-shaped spring 3 (when not rotating) is set to 80.5 mm, and the distance between the adjacent clutch shoes 2 (reference dimension when not rotating) is set to 1 mm. Is set.

  However, as shown in FIG. 3, the peripheral surface 2d is formed by partially scraping the periphery of the peripheral edge 2f of the groove 2b on the surface (opposed surface 2d) where the adjacent clutch shoes 2 are opposed to each other. A stepped portion 2e having a shape recessed inward by a predetermined amount is formed, and a separation dimension between the stepped portions 2e of adjacent clutch shoes 2 (between the opening peripheral edge portions 2f) is larger than between the opposing surfaces 2d. .

  The ring-shaped spring 3 is configured in a ring shape by connecting both ends of a spring having a strand diameter of 1.1 mm. As shown in FIG. 2, a hole 4a having the same size as the shaft hole 1a of the hub 1 is formed in the center of the two side plates 4 respectively.

  The hub 1 and each clutch shoe 2 are combined by inserting the boss 1b of the hub 1 into the notch 2c of the clutch shoe 2. Then, the circular arc-shaped groove 2b formed on each side surface of each clutch shoe 2 is annularly continued, and by fitting the ring-shaped spring 3 into the annular groove 2b, The four clutch shoes 2 are bundled in a state of being urged inward.

  Further, the two side plates 4 are slightly smaller in diameter (60 mm) than the outer peripheral portion of the concave groove 2b of the four clutch shoes 2 that are annularly continuous, and the hub 1 and the clutch shoe 2 are thin. It is attached so as to sandwich the portion (portion on the inner side in the radial direction from the concave groove 2b) from both sides and to cover the ring-shaped spring 3 mounted in the concave groove 2b from both sides.

  The drive shaft side portions combined in this way are mounted inside the clutch drum having an inner diameter of 81 mm. As described above, the diameter (when not rotating) of the clutch shoe 2 in a bundled state is set to 80.5 mm, so that the outer peripheral surface of the lining 2a of the clutch shoe 2 and the inner peripheral surface of the clutch drum when not rotating Are 0.25 mm respectively.

  The drive shaft side portion of the centrifugal clutch for rammer according to the present embodiment has the above-described configuration, and the durability can be significantly improved as compared with the conventional centrifugal clutch. This point will be described in detail. When the rammer equipped with the conventional centrifugal clutch for rammer shown in FIG. 5 is operated and the rotational speed of the drive shaft reaches a predetermined value, each clutch shoe 22 is Although it spreads outward against the urging force of the ring-shaped spring 23, it is displaced in the radial direction between the adjacent clutch shoes 22 as shown in FIG. D) may occur. Further, although the clutch shoe 22 is restrained from moving laterally by side plates 24 (see FIG. 5) disposed on both sides, it still moves slightly laterally due to large vibrations or shocks. In this case, there may be a lateral shift between the adjacent clutch shoes 22.

  The distance between the adjacent clutch shoes 22 is as narrow as about 1.35 mm even when it is expanded to contact the clutch drum by centrifugal force due to 1 mm when not rotating. On the other hand, since the element wire diameter of the ring-shaped spring 23 is 1.1 mm, if the radial shift or the lateral shift occurs between the adjacent clutch shoes, the stress is reduced even if it is a slight shift amount. Therefore, the ring-shaped spring 23 is concentrated in a very narrow range. This “part where stress is concentrated” becomes a weak point, and the ring-shaped spring 23 is considered to be broken in about 10 hours of actual operation.

  On the other hand, in the centrifugal clutch of the present embodiment, as described above, the opposing surface 2d of the clutch shoe 2 (periphery of the peripheral edge 2f of the recessed groove 2b) is recessed inward by a predetermined amount from the opposing surface 2d. Step 2e is formed, and the distance between the opening peripheral edge portions 2f of the recessed grooves 2b of the adjacent clutch shoes 2 is large. Therefore, even if a deviation occurs between the adjacent clutch shoes 2, the ring shape The concentration of stress on the spring 3 is relaxed, and as a result, the durability can be dramatically improved.

  In the present embodiment, the stepped portion 2e is formed on the facing surface 2d in order to increase the distance between the opening peripheral edge portions 2f of the concave grooves 2b of the adjacent clutch shoes 2, but FIG. As shown in the perspective view of the clutch shoe 2 of the centrifugal clutch for rammer according to the second embodiment of the invention, by chamfering the opening peripheral edge portion 2f of the concave groove 2b (forming the chamfered portion 2g), The opening peripheral edge portion 2f may be configured to be located on the inner side of the facing surface 2d, and thereby the separation dimension between the opening peripheral edge portions 2f of the concave grooves 2b of the adjacent clutch shoes 2 may be increased. Further, by combining them, the stepped portion 2e may be provided on the facing surface 2d, and the opening peripheral edge portion 2f may be chamfered.

  In the first embodiment, the boss 1b is formed on the hub 1 and the notch 2c is formed on the clutch shoe 2. However, by replacing them, the notch is formed on the hub 1, and the boss is formed on the clutch shoe 2. It may be formed.

  Furthermore, the separation dimension between the adjacent clutch shoes 2 (reference dimension when not rotating) is set to 1 mm in the first embodiment, but should be set as appropriate within a range of 0.5 to 1.5 mm. Can do. Further, the gap between the outer peripheral surface of the lining 2a of the clutch shoe 2 and the inner peripheral surface of the clutch drum when not rotating is set to 0.25 mm, but is set as appropriate within a range of 0.1 to 0.5 mm. be able to.

  Here, the durability of the centrifugal clutch for rammer according to the present invention will be described as Example 1 based on the results of tests conducted by the inventors of the present invention. First, three types of centrifugal clutches for rammer described as the first embodiment (the present inventions 1, 2, and 3) were prepared, mounted on the rammer and continuously operated, and the durability time was measured a plurality of times. In addition, as a comparative example, the conventional Rammer centrifugal clutch shown in FIG. 5 was prepared, and the same test was performed. The results are shown in Table 1 below.

  In the present invention 1, by forming the stepped portion 2e having a shape recessed inwardly by 1 mm from the opposing surface 2d on the opposing surface 2d of the clutch shoe 2 (periphery of the opening peripheral edge 2f of the concave groove 2b), The thing which expanded the separation dimension between the opening peripheral part 2f of the ditch | groove 2b of the adjacent clutch shoe 2 to 3 mm was used. Further, as a second aspect of the present invention, by forming a stepped portion 2e having a shape that is recessed 0.6 mm inward from the facing surface 2d, the separation dimension between the opening peripheral portions 2f of the recessed grooves 2b of the adjacent clutch shoes 2 can be reduced. In the present invention 3, a stepped portion 2e having a shape recessed 1.5 mm inward from the facing surface 2d is used to form the step groove 2b of the adjacent clutch shoe 2 by using the one expanded to 2.2 mm. What expanded the separation dimension between 2 f of opening peripheral parts to 4 mm was used. On the other hand, as a comparative example, a step portion is not formed, and the distance between the opening peripheral portions of the concave grooves of the adjacent clutch shoes 22 is 1 mm.

  In Table 1 above, “continuation is possible” means a state in which no problem has occurred when the endurance time measurement is completed, and the tester can be operated continuously. "Means that the ring-shaped spring has been cut and the testing machine has become inoperable, and measurement has been completed at that time.

  From the above test results, it was confirmed that each of the centrifugal clutches for rammers of the present inventions 1, 2, and 3 has extremely high durability as compared with the conventional centrifugal clutch for rammers.

  Further, based on the above test results, further consideration was given to the relationship between the distance between the opening peripheral edge of the groove groove of the adjacent clutch shoe and the durability time of the ring spring. It is not simply a proportional relationship, there is an optimal range, and furthermore, finding the optimal range for the ratio of the wire diameter of the ring spring to the separation dimension is very important for improving durability. It is considered to be important.

Specifically, when the separation dimension (when not rotating) between the opening peripheral portions of the groove grooves of adjacent clutch shoes is “S” and the wire diameter of the ring spring is “d”, the following relational expression is obtained. It is considered that extremely high durability can be expected by designing so as to satisfy.
Relational expression: S / d = 2.0 to 3.6

  When the value of S / d is less than 2.0 (for example, in the case of “Comparative Example” in Example 1 above, the value of S / d is about 0.9), the element of the ring-shaped spring is used. If the distance between the clutch shoes is too small relative to the wire diameter and the adjacent clutch shoes are displaced in the radial or lateral direction, the stress will be concentrated in a very narrow area of the ring spring, and sufficient durability will be achieved. It is known that it cannot be obtained. On the other hand, when the value of S / d is 2.0 or more (for example, in the case of “present invention 2” in the first embodiment, the value of S / d is 2.0, and in the case of “present invention 1”, S / d The value of / d is about 2.7.) From the results of Example 1, it is proved that extremely high durability can be obtained.

  However, if the value of S / d is too large beyond the appropriate range, the bending angle of the ring-shaped spring at the peripheral edge of the opening of the groove of the clutch shoe (curved concentrically with the arc of the lining in the groove of the clutch shoe) The angle between the tangent of the center line of the ring-shaped spring and the center line of the ring-shaped spring extending linearly between the adjacent clutch shoes is too large, and the stress during operation is , Concentrated on the bent portion of the ring-shaped spring (the portion of the ring-shaped spring located at the peripheral edge of the opening of the groove), conversely, the durability is lowered.

  More specifically, when the value of S / d exceeds 3.6, the bending angle of the ring-shaped spring becomes excessively large, and compared with the “comparative example” in Example 1 described above, It has been found that the effect of "improvement" cannot be expected. For example, the value of S / d of “Invention 3” in Example 1 is about 3.636, and its durability time is five times longer than that of “Comparative Example” as shown in Table 1 above. Although it is slightly inferior to “Invention 1” or “Invention 2”, it is considered that it does not reach the range of “extremely high durability”. For this reason, it is considered that the value of S / d should be set to 3.6 or less.

  Therefore, as shown in the above relational expression, design is performed by setting the separation dimension between the opening peripheral portions of the groove grooves of the adjacent clutch shoes so that the value of S / d is in the range of 2.0 to 3.6. Is preferred.

1, 2: Hub,
1a, 21a: shaft hole,
1b, 21b: Boss
2, 22: Clutch shoe,
2a, 22a: lining,
2b, 22b: concave groove,
2c, 22c: notches,
2d: opposite surface,
2e: stepped part,
2f: Opening peripheral edge of the groove,
2g: chamfered part,
3, 23: Ring-shaped spring,
4, 24: side plate,
4a: hole

Claims (4)

A drive shaft side portion including a hub, a plurality of clutch shoes arranged annularly around the hub, a ring-shaped spring that binds the clutch shoes and urges the clutch shoes inward, and the clutch shoes; It consists of a side plate that regulates movement to the side,
The hub is formed with either a plurality of bosses having a constant lateral dimension and projecting radially outward, or a plurality of notches extending radially.
The clutch shoe has a fan-shaped basic shape, an arc-shaped lining is attached to the outer peripheral side, and concentric arc-shaped concave grooves are formed on both side surfaces, respectively.
In the central portion of the clutch shoe in the radial direction, the notch corresponding to the shape of the boss formed on the hub, or the width dimension corresponding to the notch shape formed on the hub is constant, One of the bosses protruding inward in the radial direction is formed,
The hub and the clutch shoe are combined so that the clutch shoe can move in the radial direction by causing the boss formed on the other side to enter the notch formed on one of them. ,
Further, by forming a stepped portion having a shape recessed inward by a predetermined amount from the opposing surface around the peripheral edge of the opening of the concave groove on the opposing surface of the adjacent clutch shoe, A centrifugal clutch for rammer characterized in that a separation dimension is larger than a separation dimension between opposing surfaces. A drive shaft side portion including a hub, a plurality of clutch shoes arranged annularly around the hub, a ring-shaped spring that binds the clutch shoes and urges the clutch shoes inward, and the clutch shoes; It consists of a side plate that regulates movement to the side,
The hub is formed with either a plurality of bosses having a constant lateral dimension and projecting radially outward, or a plurality of notches extending radially.
The clutch shoe has a fan-shaped basic shape, an arc-shaped lining is attached to the outer peripheral side, and concentric arc-shaped concave grooves are formed on both side surfaces, respectively.
In the central portion of the clutch shoe in the radial direction, the notch corresponding to the shape of the boss formed on the hub, or the width dimension corresponding to the notch shape formed on the hub is constant, One of the bosses protruding inward in the radial direction is formed,
The hub and the clutch shoe are combined so that the clutch shoe can move in the radial direction by causing the boss formed on the other side to enter the notch formed on one of them. ,
Further, by chamfering the opening peripheral edge of the groove groove of the clutch shoe, the opening peripheral edge portion is positioned inside the opposing surface, and thereby, between the opening peripheral edge portions of adjacent clutch shoes. A centrifugal clutch for rammer characterized in that a separation dimension is larger than a separation dimension between opposing surfaces.   The centrifugal clutch for rammer according to claim 1, wherein chamfering is performed on the peripheral edge of the opening of the groove of the stepped portion.   The value of S / d is in the range of 2.0 to 3.6, where S is the distance between the opening peripheral edge portions of the groove grooves of the adjacent clutch shoes, and d is the wire diameter of the ring-shaped spring. The centrifugal clutch for rammer according to any one of claims 1 to 3, wherein the dimensions are set as described above.

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