Joint mechanism for mowing machine

Abstract: The invention provides a joint mechanism for a mowing machine which can easily be assembled and disassembled. A support member 1a of a casing 1 houses a cylindrical damper 3 which prevents vibration of a power unit A from being transmitted to a rod 10, a holder 2 to which the rod 10 is inserted and a clamp 4 which prevents the damper 3 and the holder 2 from falling off the support member 1a being inserted therein. The clamp 4 has flexible arms 4a which extend in the direction of an output shaft 11 of the power unit A, while an engagement hook 4b is formed on the tip of the arm 4a and an engagement hole 1b to which the engagement hook 4b of the clamp engages is provided on the support member 1a.

Description: The present invention relates to a machine having a joint mechanism between a power unit and a working unit thereof and particular, but not exclusively to a mowing machine, such as a brush cutter or trimmer. Mowing machines of the prior art having large total lengths include those which are divided into a power unit (for example, an engine) and a working unit (in a brush cutter for example, a rod provided with a cutting blade which is rotatably mounted on the end thereof) which can be freely joined and detached, so that the mowing machine can be stored or carried easily. A representative configuration of mowing machine which can be freely separated and joined is shown in the longitudinal sectional view of Fig. 6 (Japanese Utility Model Publication No. 6-21296). In Fig. 6, C denotes a power unit comprising an engine and B denotes a working unit with a cutting blade (not shown) mounted on the end thereof via a rod 10. In this configuration of joint mechanism, a casing 21 for a power output section is formed at a protruding side of an output shaft 11 as a part of an engine cover 26 of the power unit C, and the casing 21 has a support member 21a of cylindrical configuration which extends in the axial direction. A holder 22 of cylindrical configuration, in which the rod 10 is mounted, is supported by the support member 21a via a cylindrical damper 23 which prevents vibration of the power unit C from being transmitted to the rod 10. In order to prevent the holder 22 and the damper 23 from falling off the support member 21a of the casing, a lid member 24, which has an opening 24a formed at the center thereof to allow the rod 10 and a drive shaft 15 to penetrate therethrough, is attached to the end face of the support member 21a on the side of working unit B in the axial direction, (on left-hand side in Fig. 6) by means of a plurality of screws 25. The holder 22 has a slit 22a formed in the axial direction and flanges 22e, 22f are formed to interpose the slit 22a on both sides thereof as shown in Fig. 7 (view in line VII-VII of Fig. 6). A bolt 13 which is set in a through hole formed in the flange 22f is screwed into a threaded hole formed in the flange 22e, thereby to hold the rod 10 detacheably onto the holder 22. The casing 21 has an opening 21d formed therein to face the flanges 22e, 22f inwardly, so that the bolt 13 can be attached, detached and turned from the opening 21d. As shown in Fig. 6, the support member 21a of the casing rotatably supports the output shaft 11 which is linked to a clutch drum 14 of the engine via a bearing 12 on the side of the power unit C in the axial direction of the support member 21a, namely on a base end side (on right-hand side of the support member 21a in Fig. 6). The output shaft 11 is made in a hollow shape, while the base end of the drive shaft 15 which is arranged rotatably in the rod 10 is linked to the output shaft 11 by means of a spline or the like in the hollow space to rotate together with the output shaft 11. In a joint mechanism of such a configuration as described above, however, assembling and disassembling of the joint mechanism requires it to attach or detach the lid member 24 onto or from the casing 21 by handling the plurality of screws 25, thus making the operation tedious. The present invention has been accomplished to solve the problem of the prior art described above, and an object of the present invention is to provide a machine which allows easy assembly and disassembly of the joint mechanism thereof. The present invention provides a machine having a joint mechanism between a power unit and a working unit thereof, the joint mechanism comprising: a cylindrical support member being formed on a casing of the power unit, the cylindrical support member being on an output shaft side of the power unit and extending axially relative to the output shaft; a cylindrical holder for insertion in the support member; a rod for insertion in the holder for clamping thereby; a cylindrical damper for preventing vibration of the power unit from being transmitted to the rod; and a clamp for preventing the damper and the holder from separating from the support member when the holder, the damper and the clamp are inserted in the support member; wherein the clamp has a flexible arm extending axially and an engagement hook formed at an end of the arm; and the support member has an engagement hole with which the engagement hook of the clamp can engage. Preferably, the support member has an engaging portion formed on the inner surface thereof, the damper has an engaged portion formed on the outer surface thereof, engagement of the engaging portion with the engaged portion positioning the damper relative to the support member in a circumferential direction, and wherein the damper further has a recess formed on the outer surface thereof for positioning the clamp in the circumferential direction, the arm of the clamp fitting in the recess in the axial direction. It is advantageous if a second engaging portion is formed on an inner surface of the damper, and a second engaged portion is formed on the outer surface of the holder, engagement of the second engaging portion with the second engaged portion positioning the holder in the circumferential direction and in the axial direction. It is preferred that the holder has a relief hole formed therein to allow the arm to be deflected radially inwardly when the engagement hook of the clamp is being engaged with the engagement hole of the support member, the relief hole further allowing radially inward deflection of a portion of the damper which makes contact with the arm. It is useful to provide the machine with an engagement lock projection which is formed on the inner surface of the damper and a protruding end face of the engagement lock projection is substantially flush with the outer surface of the rod when inserted and when the engagement lock projection is engaged in the relief hole. In order that the invention may be well understood, an embodiment thereof, which is given by way of example, will be described with reference to the drawings in which: Fig. 1 is a longitudinal sectional view showing a joint mechanism of a machine according to the embodiment of the present invention; Fig. 2 is an exploded view of the joint mechanism; Fig. 3 is a horizontal sectional view showing the state of assembling the joint mechanism before the clamp and other parts are inserted into the support member; Fig. 4 is a horizontal sectional view showing the state of assembling the joint mechanism when the clamp and other parts are being inserted into the support member; Fig. 5 is a horizontal sectional view showing the state of the assembly of the joint mechanism completed with the rod inserted; Fig. 6 is a longitudinal sectional view showing a joint mechanism of a prior art machine; and Fig. 7 is a view in the direction of VII-VII of Fig. 6. First, the configuration of the joint mechanism of the machine according to the embodiment will be described. In this configuration of the joint mechanism, as shown in the longitudinal sectional view of Fig. 1, a casing (clutch case) 1 for a power output section is formed on a protruding side of an output shaft 11 as a part of an engine cover 6 of a power unit A, and the casing 1 has a support member 1a of cylindrical configuration which extends in the axial direction (i.e. axially relative to an output shaft II). A holder 2 of cylindrical configuration having a slit 2a formed therein in the axial direction is inserted in the support member 1a via a damper 3. A rod 10 of a working unit B is inserted in the holder 2 and fastened by being clamped by the holder 2. The joint mechanism has the casing 1, the holder 2 inserted in the support member 1a thereof, the damper 3 and a clamp 4, as shown in the exploded view of Fig. 2. In Figs. 1, 2 and 5, a drive shaft provided in the rod 10 is not shown. The damper 3 is made of rubber in cylindrical configuration, and has a purpose of preventing vibration of the power unit A from being transmitted to the rod 10 of the working unit B. The clamp 4 is made of resin and has a pair of flexible arms 4a which oppose each other in, for example, radial direction, and extend from the ring-shaped body 4h in the axial direction, while an engagement hook 4b is formed on the outside (the side on which the arm 4a makes contact with the inner surface of the support member 1a) of the tip of the arm 4a, for the purpose of preventing the damper 3 and the holder 2 from falling off, or separating from, the support member 1a. On the other hand, the support member 1a has a pair of engagement holes (through holes) 1b formed therein for the engagement hook 4b of the clamp 4 to engage with. The support member 1a has, for example, four projections (engaging portions) 1c (only one thereof is shown in the drawing) for positioning the damper 3 in the circumferential direction. Projections 1c are formed on the inner surface of the support member 1a and are spaced in the circumferential direction and extend in the axial direction. Four recesses 3c for engaging with projections 1c, are formed on the outer surface of the damper 3. Each recess 3c has a groove shape. A pair of recesses 3a are formed on the outer surface of the damper for engaging with arms 4a of the clamp to position the clamp relative to the damper in the circumferential direction. Each recess 3a has a groove shape and extends axially to fit with one of the arms 4a. The damper 3 also has a pair (only the lower side is shown) of recesses (second engaging portions) 3d formed in I shape in the axial direction and a pair of the recesses 3d formed in a rectangular shape for the positioning of the holder, while a pair of I-shaped positioning projections (second engaged portions) 2d and a pair of rectangular positioning projections 2d fit in the respective recesses 3d formed on the outer surface of the holder 2 (only the upper side of the I-shaped projections and the right-hand side, when viewed in front of the support member 1a, of the rectangular projections are shown in the drawing). The holder 2 has a pair (only the right-hand side is shown) of rectangular relief holes (through holes) 2b formed to correspond with the arms 4a of the clamp. Relief holes 2b allow arms 4a to deflect inwardly when the engagement hook 4b of the clamp is engaged with the engagement hole 1b of the support member. A portion of the damper 3 which makes contact with the arm 4a also deflects inwardly in the relief hole 2b (Fig.4). The damper 3 has engagement lock projections 3b (only the left-hand side is shown) of which protruding end face 3g becomes substantially flush with the outer surface of the rod 10 when engaged in the relief hole 2b and the rod 10 is inserted (Fig.5). The Engagement Lock projection are formed on the inner surface of the damper 3 corresponding to the relief holes 2b of the holder 2. The holder 2 also has flanges 2e, 2f being formed on both sides of the slit 2a, which is made in the axial direction wherein a bolt (for example a hexagonal socket head bolt) 13 which is set in a through hole formed in the flange 2f is screwed into a threaded hole formed in the flange 2e (located on the right-hand side in the drawing), thereby to hold the rod 10 detacheably onto the holder 2. The support member 1a is preferably made in such a tapered configuration as the outer diameter thereof increases toward the side of the power unit A, namely the base side (the right-hand side in Fig. 2) and the inner diameter decreases toward the base for the reason of forming the casing 1 in a die. Because the outer surface of the damper 3 makes contact with the inner surface of the support member 1a, the damper 3 is also preferably made in such a tapered configuration as the outer diameter decreases toward the base (the right-hand side in Fig. 2). In order to ensure tight engagement with the inner surface of the support member 1a, outer surface of the damper 3 preferably has a plurality of projections 3e of, for example, rectangular configuration formed on the base side and the working unit B side (namely on the near left-hand side in Fig. 2) being distributed in the circumferential direction. Now the operation/working effect of the joint mechanism, namely assembly of the joint mechanism, attaching and detaching the rod 10 and disassembly of the joint mechanism will be described below. For the ease of drawing, tapering of the inner surface of the support member 1a and tapering of the outer surface of the damper 3 are not shown in Fig. 3, 4 and 5. When assembling the joint mechanism, as shown in the horizontal sectional view of Fig. 3, the holder 2 is passed through the body 4h of the clamp 4, then the holder 2 is inserted in the damper 3 while expanding the damper 3 by using the elastic force of the damper 3. In order to prevent the clamp 4 from coming off the tip 2c (on the left-hand side in Fig. 3) of the holder 2, inner diameter D of the body 4h of the clamp 4 is preferably made smaller than the outer diameter d of the tip 2c of the holder 2 where the flanges 2e, 2f (Fig. 1,2) are formed. The body 4h of the clamp 4 has a groove 4d formed on the inner diameter wherein the positioning projection 2d on the outer surface of the holder 2 can pass through (Fig.2). At this time, the positioning projection 2d on the outer surface of the holder 2 is fitted in the holder positioning recess 3d on the inner surface of the damper 3, thereby positioning the holder 2 both in the circumferential direction and axial direction and integrating the holder 2 with the damper 3. At the same time, the engagement lock projection 3b provided on the inner surface of the damper 3 is fitted in the relief hole 2b of the holder 2, whereupon a base end face 2h of the holder 2 makes contact with an inner surface 3h at the base end of the damper 3. Further, the arms 4a of the clamp are inserted (fitted) in the axial direction in the recesses 3a for positioning in circumferential direction of the clamp provided on the outer surface of the damper 3. In order to make it easier to insert the engagement hook 4b of the clamp in the support member 1a (Fig. 4), it is preferable that the amount of outward projection H in the radial direction decrease toward the base end 4f (right-hand side in Fig. 3) and become zero at the base end 4f. The holder 2, the damper 3 and the clamp 4 which are integrally combined are inserted in the support member 1a by using a jig 7 of bottomed cylinder configuration as shown in Fig. 4. That is, an outer end face 2g' of the tip 2c of the holder 2 is pressed with an inner bottom face 7a of the jig 7 and, at the same time, an outer end face 4g of the body 4h of the clamp 4 is pressed with a side end face 7b of the jig 7, thereby inserting the holder 2, the damper 3 and the clamp 4 in the support member 1a. At this time, the damper 3 is pushed by the holder 2 which is integrated therewith and is also pushed by an inner end face 4e of the body 4h of the clamp 4. Although an inner end face 2g of the tip 2c of the holder 2 and the outer end face 4g of the body 4h of the clamp 4 are separated at a distance not to contact each other in the configuration of the joint mechanism of this embodiment, such a configuration may also be employed that these end faces are in contact with each other and only the outer end face 2g' of the tip 2c of the holder 2 is pushed by means of a jig of a simple plate shape, thereby inserting the holder 2, the damper 3 and the clamp 4 in the support member 1a. At this time, because the holder 2 is positioned in the circumferential direction with respect to the support member 1a via the damper 3 by fitting the recesses 3c for positioning in the circumferential direction on the outer surface of the damper with the projections 1c for the positioning of the damper 3 in the circumferential direction provided on the inner surface of the support member 1a of Fig. 2, the slit 2a of the holder can be positioned at a specified position (downward in this case) in the circumferential direction with respect to the support member 1a, namely the casing 1, as shown in Fig. 1. When the engagement hook 4b of the clamp is inserted in the support member 1a as shown in Fig. 4, the clamp arm 4a is pushed inwardly in the radial direction by the inner surface of the support member 1a and is deflected inwardly. A portion of the damper 3 which is in contact with the arm 3a is also deflected inwardly and enters the relief hole 2b of the holder. Further, the projected end face 3g of the engagement lock projection 3b of the damper which is fitted in the relief hole 2b comes off by deflecting more inwardly than the inner surface of the holder 2. Thus because the arm 4a is deflected inwardly, it is made easier to insert the holder 2, the damper 3 and the clamp 4 which are combined integrally in the support member 1a. When the tip 4b' (on the left-hand side in Fig. 4) of the engagement hook 4b of the clamp reaches the engagement hole 1b of the support member, as shown in Fig. 5, the clamp arm 4a which has been deflected returns outward by the elasticity of itself and the damper 3 so that the engagement hook 4b of the clamp engages with the engagement hole 1b of the support member. At this time, because the clamp arm 4a is fitted in the recess for positioning in the circumferential direction of the clamp on the outer surface of the damper 3 and is positioned in the circumferential direction with respect to the support member 1a of the casing via the damper 3, it is made easier to engage the engagement hook 4b of the clamp with the engagement hole 1b of the support member. Also at this time, the base end face 3f of the damper 3 makes contact with the base end face 1f located inward of the support member 1a (Fig.5). In this state, engagement of the engagement hook 4b of the clamp with the engagement hole 1b prevents the clamp 4, the damper 3 and the holder 2 from falling off the support member 1a, thus completing the assembly of the joint mechanism. Therefore, according to the joint mechanism of the embodiment, the joint mechanism can be easily assembled simply by inserting the clamp 4 together with the holder 2 and the damper 3 into the support member 1a of the casing and causing the engagement hook 4b of the clamp to engage with the engagement hole 1b of the support member. In the joint mechanism assembled as described above, as shown in Fig. 1, the tip 2c of the holder 2 with the flanges 2e, 2f formed thereon protrudes from the support member 1a, thereby enabling it to attach or detach the rod 10 to or from the holder 2 freely by tightening or loosening the bolt 13. The support member 1a of the casing supports the output shaft 11 which is linked to the clutch drum 14 of the engine freely rotatably via the bearing 12 at the portion of power unit A side in the axial direction, namely the base end side (right-hand side in Fig. 1) similarly to the prior art. And the output shaft 11 has a hollow space inside to which the base end of the drive shaft (not shown) which is disposed freely rotatably in the rod 10 is linked by means of a spline or the like to be rotatable along with the output shaft 11. Fig. 5 shows a horizontal sectional view in the state of the rod 10 being inserted. In this state, because the protruding end face 3g of the engagement lock projections 3b becomes substantially flush with the outer surface of the rod 10 and the arm 4a is difficult to deflect inwardly, the engagement hook 4b of the clamp does not accidentally disengage from the engagement hole 1b of the support member, thus making the assembly of the joint mechanism and holding of the rod 10 in the support member 1a more secure. In order to disassemble the joint mechanism for servicing the engine or other part, first the rod 10 is removed from the holder 2. Then while pressing the engagement hook 4b of the clamp inwardly from the engagement hole 1b of the support member 1a, the holder 2 is pulled by holding the tip 2c thereof to release the engagement hook 4b of the clamp from the engagement hole 1b into the state shown in Fig. 4 (the jig 7 is not necessary). By continuing to pull the holder 2 toward the tip side, the damper 3 and the clamp 4 as a whole can also be pulled out of the support member 1a. Thus according to the joint mechanism of the embodiment, the joint mechanism can be easily disassembled simply by releasing the engagement hook 4b of the clamp from the engagement hole 1b without unscrewing the plurality of screws and removing the lid member. In summary, in the embodiment described above, a joint mechanism of a mowing machine comprises a cylindrical support member being formed on a casing for power output section formed at a protruding side of an output shaft of a power unit and extending in the axial direction, a cylindrical holder being inserted in the support member and a rod which is inserted in the holder and is held by clamping the holder, wherein a cylindrical damper which prevents vibration of the power unit from being transmitted to the rod, the holder, and a clamp which prevents the damper and the holder from falling off the support member are inserted in the support member; and the clamp has a flexible arm extending in the axial direction and an engagement hook formed at an end of the arm; and the support member has an engagement hole to which the engagement hook of the clamp engages. The embodiment enables the joint mechanism to be assembled simply by inserting the clamp together with the holder and the damper into the support member of the casing and engaging the engagement hook of the clamp with the engagement hole. Also the joint mechanism can be disassembled simply by releasing the engagement, thus making it easier to assemble and disassemble. One of the advantages with the embodiment is that the support member has an engaging portion for positioning of the damper in the circumferential direction being formed on the inner surface of the support member, an engaged portion for positioning in the circumferential direction which fits therein is formed on the outer surface of the damper, and a recess for positioning of the clamp in the circumferential direction wherein the arm of the clamp fits in the axial direction is formed on the outer surface of the damper. With this configuration, the arm of the clamp is positioned while being fastened in the circumferential direction with respect to the support member of the casing via the damper, meaning that the engagement hook of the clamp can be easily engaged with the engagement hole of the support member, thereby further aiding assembly of the joint mechanism. Another of the advantages with the embodiment is that the damper has an engaging portion for positioning of the holder in the circumferential direction and in the axial direction being formed on the inner surface of the damper, and an engaged portion for positioning in the circumferential direction and in the axial direction which fits therein is formed on the outer surface of the holder. With this configuration, the holder is positioned while being fastened both in the circumferential direction and axial direction onto the damper and is integrally combined with the damper, meaning that the damper can be easily pulled out of the support member of the casing together with the holder when disassembling the joint mechanism. When the damper is positioned in the circumferential direction with respect to the support member as mentioned above, the holder is also positioned in the circumferential direction with respect to the support member via the damper, and therefore the holder is positioned in the circumferential direction with respect to the support member, namely the casing, thereby making it even easier to assemble the joint mechanism. One of the preferred aspects of the embodiment is that the holder has a relief hole formed therein so that, in case the arm is deflected inwardly when the engagement hook of the clamp engages with the engagement hole of the support member, a portion of the damper which makes contact with the arm is deflected inwardly in the relief hole. According to this configuration, because the arm can easily deflect inwardly due to the relief hole being formed in the holder, the engagement hook of the clamp can be easily engaged in the engagement hole of the support member and released therefrom, thereby making it easier to assemble and disassemble the joint mechanism. Another aspect of the embodiment is that an engagement lock projection of which protruding end face becomes substantially flush with the outer surface of the rod, when engaged in the relief hole and the rod is inserted, is formed on the inner surface of the damper. This aspect is advantageous because it becomes difficult for the arm to deflect inwardly when the rod is inserted because the protruding end face of the engagement lock projection on the inner surface of the damper becomes substantially flush with the outer surface of the rod, the engagement hook of the clamp is less likely to come off the engagement hole of the support member, thereby making the assembly of the joint mechanism and holding of the rod in the support member more secure. As described above, the machine of the present invention can be easily assembled and disassembled, in that the joint mechanism thereof can be assembled simply by inserting the clamp, the holder and the damper into the support member of the casing and putting the engagement hook of the clamp into engagement with the engagement hole of the support member, and the joint mechanism can be disassembled simply by releasing the engagement.

Claims: A machine having a joint mechanism between a power unit and a working unit thereof, the joint mechanism comprising: a cylindrical support member (1a) being formed on a casing (1) of the power unit, the cylindrical support member (1a) being on an output shaft side of the power unit and extending axially relative to the output shaft; a cylindrical holder (2) for insertion in the support member (1a) ; a rod (10) for insertion in the holder (2) for clamping thereby; a cylindrical damper (3) for preventing vibration of the power unit from being transmitted to the rod (10); and a clamp (4) for preventing the damper and the holder (2) from separating from the support member (1a) when the holder (2), the damper (3) and the clamp (4) are inserted in the support member (1a); wherein the clamp (4) has a flexible arm (4a) extending axially and an engagement hook (4b) formed at an end of the arm (4a); and the support member (1a) has an engagement hole (1b) with which the engagement hook (4b) of the clamp can engage. A machine as claimed in claim 1, wherein the support member (1a) has an engaging portion (1c) formed on the inner surface thereof, the damper has an engaged portion (3c) formed on the outer surface thereof, engagement of the engaging portion (1c) with the engaged portion (3c) positioning the damper (3) relative to the support member (1a) in a circumferential direction, and wherein the damper (3) further has a recess (3a) formed on the outer surface thereof for positioning the clamp (4) in the circumferential direction, the arm (4a) of the clamp (4) fitting in the recess (3a) in the axial direction. A machine as claimed in claim 1 or 2, wherein a second engaging portion (3d) is formed on an inner surface of the damper (3), and a second engaged portion (2d) is formed on the outer surface of the holder (2), engagement of the second engaging portion (3d) with the second engaged portion (2d) positioning the holder (2) in the circumferential direction and in the axial direction. A machine as claimed in any one of claims 1 to 3, wherein the holder (2) has a relief hole (2b) formed therein to allow the arm (4a) to be deflected radially inwardly when the engagement hook (4b) of the clamp (4) is being engaged with the engagement hole (1b) of the support member (1a), the relief hole (2b) further allowing radially inward deflection of a portion of the damper (3) which makes contact with the arm (4a). A machine as claimed in claim 4, wherein an engagement lock projection (3b) is formed on the inner surface of the damper (3) and a protruding end face of the engagement lock projection (3b) is substantially flush with the outer surface of the rod (10) when inserted and when the engagement lock projection (3b) is engaged in the relief hole (2b).

Inventors: TAKEMOTO KAZUHIKO, YAMANE YOSHIRO, YASHIRODAI TADAO, YUASA TSUNEYOSHI, TAKEMOTO, KAZUHIKO, YAMANE, YOSHIRO, YASHIRODAI, TADAO, YUASA, TSUNEYOSHI
Applicants: KAWASAKI HEAVY IND LTD, KAWASAKI JUKOGYO KABUSHIKI KAISHA
Application year: 1998
Main classification: A01D34
IPC codes: A01D34, F16D1