JP4542019B2 - Cylinder device - Google Patents

Description

  The present invention relates to a cylinder device that is preferably used for a working device of a construction machine such as a hydraulic excavator or a wheel loader.

  In general, a working device for a hydraulic excavator used for excavation work such as earth and sand includes a boom that is provided on an upper swing body so as to be able to be lifted and lowered, an arm that is provided so as to be pivotable on a tip end side of the boom, The boom, the arm, and the bucket are each configured to be driven by a cylinder device such as a hydraulic cylinder.

  Here, the cylinder device is usually composed of a tube and a rod that protrudes from one end side of the tube so as to expand and contract and is provided with a boss portion for pin coupling on the protruding end side. It is known that the cylinder device used for the above-mentioned is provided with a protective cover that covers the rod in order to prevent the rod protruding from the tube from colliding with earth and sand, rocks, etc. during excavation work.

  And the protective cover of the cylinder apparatus by this prior art is a rod which is fixed to the boss | hub part of a rod using the volt | bolt at one end side of a length direction, and the other end side is supported so that a movement is possible to a tube, and expands-contracts with respect to a tube Is covered from the outer peripheral side. Thereby, it can suppress that earth and sand, rocks, etc. collide with the rod which protruded from the tube, and can protect a rod from these earth and sand etc. (for example, refer to patent documents 1).

JP 2002-220853 A

  However, the above-described cylinder device according to the prior art has a structure in which a screw seat is provided on the boss portion of the rod, and one end side of the protective cover is fixed to the boss portion using a bolt screwed to the screw seat. .

  For this reason, the cylinder device according to the prior art needs to fix the screw seat for attaching the protective cover to the boss portion of the rod by means of welding or the like, and there is a problem that workability when attaching the protective cover is poor. is there.

  In addition, the cylinder device according to the prior art needs to provide a screw seat on the boss of the rod when the protective cover is attached, and it is not necessary to provide a screw seat on the boss of the rod when the protective cover is not attached. Depending on the necessity of the protective cover, it is necessary to prepare two types of cylinder devices, and there is a problem that the number of parts increases and parts management becomes complicated.

  The present invention has been made in view of the above-described problems of the prior art, and an object of the present invention is to provide a cylinder device capable of improving workability when a protective cover is attached.

  In order to solve the above-described problems, the present invention provides a tube, a rod that protrudes from one end side of the tube so as to be extendable and has a boss portion for pin coupling on the protruding end side, and one end side is supported by the rod. The present invention is applied to a cylinder device that includes a protective cover that protects the rod and is supported on the tube so as to be movable at the other end.

  A feature of the configuration adopted by the invention of claim 1 is that a cover for attaching the protective cover to the rod by sandwiching a boss portion of the rod from the front and rear in the axial direction at one end side of the protective cover. The mounting member is provided.

  According to a second aspect of the present invention, the cover mounting member is provided on one end side of the protective cover and is in contact with the outer peripheral surface of the boss portion on the side opposite to the rod, and is movable with respect to the corresponding contact plate. It is constituted by a movable plate that sandwiches the boss portion with the contact plate by contacting the outer peripheral surface of the boss portion on the rod side.

  According to a third aspect of the present invention, a cylindrical nipple guard is provided on the boss portion of the rod so as to surround the periphery of the grease nipple, and the contact plate of the cover mounting member is provided on the nipple guard. The configuration is such that a fitting hole to be fitted is provided.

  According to a fourth aspect of the present invention, a cover slide mechanism that slidably supports the protective cover according to expansion and contraction of the rod is provided on one end side of the tube.

  According to the first aspect of the present invention, a screw is attached to the rod by sandwiching the boss portion provided on the protruding end side of the rod from the front and rear in the axial direction of the rod by the cover mounting member provided on one end side of the protective cover. Since one end side of the protective cover can be easily attached to the rod without providing a seat, workability when the protective cover is attached can be improved. In addition, since it is not necessary to provide a screw seat for mounting the protective cover on the rod, there is no need to prepare two types of cylinder devices according to the necessity of the protective cover, the number of parts can be reduced, and parts management is simplified. It can also contribute to the conversion.

  According to the invention of claim 2, since the cover mounting member is constituted by the contact plate provided on one end side of the protective cover and the movable plate that is movable with respect to the corresponding contact plate, With the abutment plate in contact with the outer peripheral surface on the opposite rod side, the abutment plate is brought into contact with the outer peripheral surface on the rod side of the boss by moving the movable plate closer to and away from the contact plate. The boss portion of the rod can be securely sandwiched between the plate and the movable plate. Therefore, for example, even when the shape of the boss portion changes depending on the type of the cylinder device, the one end side of the protective cover can be securely attached to the rod by firmly sandwiching the boss portion between the contact plate and the movable plate. it can.

  According to the invention of claim 3, in the state where the fitting hole provided in the contact plate of the cover mounting member is fitted to the nipple guard protruding from the boss portion of the rod, the contact plate and the movable plate By sandwiching the boss portion therebetween, it is possible to prevent the protective cover attached to the boss portion from being displaced in a direction perpendicular to the axial direction of the rod. Thereby, a protective cover can be hold | maintained in a proper attitude | position and a rod can be reliably protected by this protective cover.

  According to the invention of claim 4, the protective cover can be slidably supported by the cover slide mechanism provided on one end side of the tube, so that the protective cover can be smoothly moved following the expansion and contraction of the rod, The rod can be reliably protected by the protective cover.

  Hereinafter, a cylinder device according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 13 by taking as an example a case where the cylinder device is applied to a hydraulic excavator.

  In the figure, 1 is a hydraulic excavator, and the hydraulic excavator 1 is roughly constituted by a crawler-type lower traveling body 2 that can be self-propelled and an upper revolving body 3 that is pivotably mounted on the lower traveling body 2. A working device 4 to be described later is provided on the front side of the upper swing body 3.

  Reference numeral 4 denotes an offset type working device provided on the front side of the upper swing body 3 so as to be able to move up and down. The work device 4 includes a lower boom 5 attached to a swing frame 3A of the upper swing body 3, and the lower boom 5 An upper boom 6 attached to the distal end side of the upper boom 6, an arm support member 7 attached to the distal end side of the upper boom 6, an arm 8 attached to the distal end side of the arm support member 7, and a distal end side of the arm 8. The bucket 9 is provided, and a link rod 10 that connects the lower boom 5 and the arm support member 7 is provided.

  A boom cylinder 11 is provided between the swing frame 3A and the lower boom 5, an offset cylinder 12 is provided between the lower boom 5 and the upper boom 6, and an arm is provided between the arm support member 7 and the arm 8. A cylinder 13 is provided, and a bucket cylinder 21 described later is provided between the arm 8 and the bucket 9 via a bucket link 14. Then, the work device 4 rotates the lower boom 5, the arm 8, and the bucket 9 in a state in which the upper boom 6 is translated (offset) in the left and right directions with respect to the lower boom 5. Excavation work is performed.

  Reference numeral 21 denotes a bucket cylinder as a cylinder device provided between the arm 8 and the bucket link 14. The bucket cylinder 21 rotates the bucket 9 with respect to the arm 8. And the bucket cylinder 21 is comprised by the below-mentioned tube 22, the rod 23, the protective cover 26, etc., as shown in FIG. 2 thru | or FIG.

  Reference numeral 22 denotes a cylindrical tube constituting the bucket cylinder 21, and the tube 22 is opened at one end side (rod guide side) in the length direction and the other end side (bottom side) is rotated to the upper surface side of the arm 8. It is pin-coupled (see FIG. 1). A piston (not shown) is slidably fitted in the tube 22, and the other end of a rod 23 described later is fixed to the piston.

  Reference numeral 23 denotes a cylindrical rod that protrudes from one end side of the tube 22 so that the rod 23 can extend and contract. The other end side of the rod 23 is fixed to a piston (not shown) in the tube 22, and one end side of the rod 23 is connected to the tube 22. Projects outward from one end. A boss portion 24 described later is provided on the protruding end side of the rod 23.

  Reference numeral 24 denotes a cylindrical boss part integrally provided on the protruding end side of the rod 23, and a pin insertion hole 24 </ b> A extending in a direction orthogonal to the axial direction of the rod 23 is formed on the inner peripheral side of the boss part 24. Has been. The rod 23 and the bucket link 14 are pin-coupled using the pin 25 inserted through the pin insertion hole 24A (see FIG. 1).

  Here, the boss portion 24 has a rod-side outer peripheral surface 24 </ b> B joined to the tip of the rod 23, and an anti-rod-side outer peripheral surface 24 </ b> C located on the opposite side of the rod 23. As shown in FIG. 6 and the like, the boss portion 24 is provided with a greasing hole 24D from the outer peripheral surface 24C on the non-rod side toward the pin insertion hole 24A, and the greasing hole 24D has grease or the like. A grease nipple 24E for supplying the lubricating oil is attached. A cylindrical nipple guard 24F is provided on the outer peripheral surface 24C of the boss portion 24 on the side opposite to the rod so as to surround and protect the grease nipple 24E.

  Then, the bucket cylinder 21 is responsive to the sliding displacement of the piston within the tube 22 when pressure oil from a hydraulic pump (not shown) mounted on the upper swing body 3 is supplied to and discharged from the tube 22. Accordingly, the rod 23 is expanded and contracted with respect to the tube 22. As a result, the expansion and contraction operation of the rod 23 is transmitted to the bucket 9 via the bucket link 14, and the bucket 9 rotates on the tip side of the arm 8 to perform excavation work such as earth and sand.

  Reference numeral 26 denotes a protective cover extending in the axial direction (length direction) of the rod 23 from the boss portion 24 of the rod 23 to one end side (tip end side) of the tube 22, and the protective cover 26 surrounds the rod 23 protruding from the tube 22. By covering from the side, the rod 23 is protected from collision with earth and sand during excavation work. The protective cover 26 is attached to the boss portion 24 of the rod 23 at one end side in the length direction by a cover attaching member 27 described later, and the other end side in the length direction becomes a free end to the tube 22 by a cover slide mechanism 32 described later. It is supported so as to be movable.

  Here, as shown in FIGS. 4 and 9, etc., the protective cover 26 is formed by bending a steel plate material, for example, has a width dimension larger than the outer diameter dimension of the tube 22, and the rod 23 The upper plate portion 26A that extends in the axial direction (length direction) of the rod 23 while facing the outer peripheral surface of the rod 23 is disposed on both ends in the width direction of the upper plate portion 26A, and has a substantially L-shaped cross-sectional shape. It is comprised by a pair of groove part 26B, 26B which faces.

  The upper plate portion 26A is integrally formed with a pair of protrusions 26C, 26C extending in the length direction at a constant interval in the width direction, and each protrusion 26C is a triangle protruding upward from the upper plate portion 26A. The cross-sectional shape of the upper plate portion 26A against the collision of earth and sand is increased. A cover mounting member 27 (described later) is provided on one end side in the length direction of the protective cover 26.

  A cover mounting member 27 is provided on one end side (tip side) of the protective cover 26 in the length direction. The cover mounting member 27 sandwiches the boss portion 24 of the rod 23 from the front and rear in the axial direction of the rod 23. As a result, one end of the protective cover 26 is attached to the rod 23. And the cover attachment member 27 is comprised by the below-mentioned contact plate 28, movable plate 29 grade | etc., As shown in FIG.6 and FIG9.

  Reference numeral 28 denotes a contact plate provided on one end side of the protective cover 26, and the corresponding contact plate 28 is formed in a substantially T shape using a steel plate material thicker than the protective cover 26, for example. A wide width portion 28A having the same width dimension and a narrow width portion 28B having a width dimension substantially equal to the boss portion 24 of the rod 23 are configured. Then, the base end portion of the wide width portion 28A is fixed to one end side of the protective cover 26 using means such as welding, and the distal end side of the narrow width portion 28B is inclined obliquely downward, as shown in FIG. The boss portion 24 comes into contact with the outer peripheral surface 24C on the side opposite to the rod.

  Here, a pair of reinforcing plates 28C and 28C are fixed to both sides in the width direction of the contact plate 28 by welding or the like, and the other end side of each of the reinforcing plates 28C is a projection 26C provided on the protective cover 26. It is fixed to the tip side of each by welding or the like. In addition, a long hole 28D extending in the axial direction of the rod 23 is formed in the center portion in the width direction of the narrow width portion 28B located between the reinforcing plates 28C, and a bolt 30 described later is inserted into the long hole 28D. Is.

  Reference numeral 28E denotes a fitting hole formed on the distal end side of the narrow width portion 28B. The fitting hole 28E is an outer peripheral side of a nipple guard 24F provided in the boss portion 24 of the rod 23 as shown in FIG. To be fitted. Further, an annular protrusion 28F having an inner diameter dimension equal to that of the fitting hole 28E is fixed concentrically with the fitting hole 28E on the distal end side of the narrow width portion 28B, and the inner peripheral side of the annular protrusion 28F is connected to the fitting hole 28E. It fits on the outer peripheral side of the nipple guard 24F together with 28E. Accordingly, the contact plate 28 is hooked on the nipple guard 24F by the fitting hole 28E and the annular protrusion 28F, and the contact plate 28 can be prevented from being displaced in the direction orthogonal to the axial direction of the rod 23. It has become.

  A movable plate 29 is provided so as to be movable with respect to the contact plate 28. The movable plate 29 is formed, for example, by bending a steel plate material thicker than the protective cover 26 into a substantially L shape. It is comprised by the horizontal surface part 29A attached to the narrow part 28B of the contact plate 28, and the vertical surface part 29B which hangs downward from this horizontal surface part 29A. A female screw hole 29C is screwed at the center of the horizontal surface portion 29A, and a bolt 30 inserted through the long hole 28D of the contact plate 28 is screwed into the female screw hole 29C, so that the lower surface side of the contact plate 28 is formed. A movable plate 29 is attached, and the vertical surface portion 29B is in contact with the outer peripheral surface 24B on the rod side of the boss portion 24 via an elastic body 31 described later (see FIG. 6).

  In this case, since the movable plate 29 can move with respect to the contact plate 28 in the range of the long hole 28D, the distal end side of the contact plate 28 (narrow width portion 28B) is arranged on the outer periphery of the boss portion 24 on the opposite rod side. The movable plate 29 is moved in the axial direction of the rod 23 along the long hole 28D while being in contact with the surface 24C, whereby the vertical surface portion 29B of the movable plate 29 is moved to the outer peripheral surface 24B on the rod side of the boss portion 24. It can be made to contact. Accordingly, the boss portion 24 can be reliably sandwiched by the contact plate 28 and the movable plate 29 from the front and the rear of the rod 23 in the axial direction, and one end side of the protective cover 26 is connected to the rod using the cover mounting member 27. 23 is configured to be securely fixed to 23.

  Reference numeral 31 denotes an elastic body attached to the lower end edge of the vertical surface portion 29B constituting the movable plate 29. The elastic body 31 is formed by using an elastic material such as rubber, for example, as shown in FIG. The lower surface of 31 is an arcuate curved surface 31 </ b> A corresponding to the outer peripheral surface of the rod 23. When the elastic body 31 sandwiches the boss portion 24 of the rod 23 between the contact plate 28 and the movable plate 29, the elastic body 31 makes the curved surface 31 </ b> A contact the outer peripheral surface of the rod 23, thereby In addition to stabilizing the posture, the movable plate 29 prevents the outer peripheral surface of the rod 23 from being damaged.

  A cover slide mechanism 32 is provided on one end side of the tube 22, and the cover slide mechanism 32 movably supports the free end side of the protective cover 26 when the rod 23 expands and contracts with respect to the tube 22. It is. And the cover slide mechanism 32 is comprised by the below-mentioned clamp members 33 and 34, the guide plate 37, the sliding member 38, etc., as shown in FIG.5, FIG8 and FIG.9.

  Reference numerals 33 and 34 denote a pair of clamp members fixed to the outer peripheral side of the tube 22. Each of the clamp members 33 and 34 has a semicircular arc shape having a curvature substantially equal to the outer peripheral surface of the tube 22 using, for example, a thin steel plate material. It is formed as a plate body. And each clamp member 33,34 is fixed to the outer peripheral side of the tube 22 by fastening the both ends using the bolt 35 and the nut 36 in the state which pinched | interposed the one end side of the tube 22 from radial direction. It is what is done.

  Reference numeral 37 denotes a guide plate fixed to one clamp member 33. The guide plate 37 is formed in a rectangular flat plate shape extending in the width direction of the protective cover 26 as shown in FIG. The upper surface of 33 is fixed by means such as welding. Then, as shown in FIG. 8, the protective cover 26 is clamped by engaging both longitudinal ends of the guide plate 37 with respective groove portions 26B of the protective cover 26 via sliding members 38 described later. It is configured to move (slide) in the axial direction of the rod 23 along the guide plate 37 while being guided by the guide plate 37 fixed to the tube 22 via 33.

  38 and 38 are a pair of sliding members attached to both ends in the longitudinal direction of the guide plate 37. The sliding member 38 is formed in a bottomed box shape using, for example, a rubber material, a resin material, The guide plate 37 is inserted into both end sides. The sliding member 38 smoothly moves the protective cover 26 along the guide plate 37 by reducing friction generated at the contact portion of the protective cover 26 with the groove 26B.

  The bucket cylinder 21 according to the present embodiment has the above-described configuration, and the hydraulic excavator 1 provided with the bucket cylinder 21 offsets the upper boom 6 with respect to the lower boom 5 by expanding and contracting the offset cylinder 12, for example. In this state, the boom cylinder 11, the arm cylinder 13, and the bucket cylinder 21 are expanded and contracted to rotate the lower boom 5, the arm 8, and the bucket 9 to perform excavation work such as earth and sand.

  During the excavation work, the protective cover 26 of the bucket cylinder 21 covers the rod 23 from the outer peripheral side while following the expansion and contraction of the rod 23 with respect to the tube 22, so that the protective cover 26 prevents the earth and sand from colliding with the rod 23. Therefore, the bucket cylinder 21 can be stably operated over a long period of time.

  Here, in the present embodiment, the workability when the protective cover 26 is attached to the bucket cylinder 21 can be improved. Hereinafter, referring to FIG. 9 to FIG. However, it will be explained.

  First, as shown in FIG. 9, with the sliding members 38 attached to both ends of the guide plate 37 fixed to the clamp member 33, both ends of the guide plate 37 are inserted into the grooves 26 </ b> B of the protective cover 26. Engage. On the other hand, a bolt 30 is inserted into the long hole 28D of the contact plate 28 fixed to the protective cover 26, and the bolt 30 is screwed into the female screw hole 29C of the movable plate 29, so that the lower surface side of the contact plate 28 is provided. The movable plate 29 is movably attached.

  Next, as shown in FIG. 10, the fitting hole 28 </ b> E and the annular protrusion 28 </ b> F provided on the distal end side of the contact plate 28 are fitted on the outer peripheral side of the nipple guard 24 </ b> F provided on the boss portion 24 of the rod 23. The tip side of the contact plate 28 is brought into contact with the outer peripheral surface 24 </ b> C on the side opposite to the rod of the boss portion 24. In this state, the movable plate 29 attached to the lower surface side of the contact plate 28 is moved in the axial direction of the rod 23 within the range of the long hole 28D through which the bolt 30 is inserted, whereby the vertical surface portion 29B of the movable plate 29 is obtained. Is brought into contact with the outer peripheral surface 24B of the boss portion 24 on the rod side. As a result, as shown in FIG. 11, the abutting plate 28 and the movable plate 29 allow the boss portion 24 to be securely sandwiched from the front and rear in the axial direction of the rod 23, and a screw seat is provided on the rod 23 and the like. Therefore, the one end side of the protective cover 26 can be securely fixed to the rod 23.

  In this case, the fitting hole 28E and the annular protrusion 28F provided on the distal end side of the contact plate 28 are fitted to the nipple guard 24F provided on the outer surface 24C on the opposite side of the boss portion 24, so that It is possible to prevent the protective cover 26 from being displaced in a direction orthogonal to the axial direction of the rod 23 in a state where the boss portion 24 is sandwiched between the contact plate 28 and the movable plate 29. On the other hand, since the elastic body 31 having the arcuate curved surface 31A is attached to the lower end edge of the vertical surface portion 29B of the movable plate 29, the boss portion 24 of the rod 23 is sandwiched between the contact plate 28 and the movable plate 29. Sometimes, the curved surface 31A of the elastic body 31 is brought into contact with the outer peripheral surface of the rod 23, thereby stabilizing the posture of the movable plate 29 and suppressing the outer peripheral surface of the rod 23 from being damaged by the movable plate 29. it can.

  In this way, as shown in FIG. 11, after the one end side of the protective cover 26 is attached to the boss portion 24 of the rod 23 by the cover attaching member 27 comprising the contact plate 28 and the movable plate 29, the protective cover 26 The clamp member 33 attached to the other end side of the tube 22 via the guide plate 37 is engaged with the outer peripheral surface on the one end side of the tube 22. Then, with the clamp member 33 and another clamp member 34 sandwiching one end side of the tube 22 from the radial direction, both end sides of the clamp members 33 and 34 are fastened using bolts 35 and nuts 36.

  As a result, as shown in FIGS. 3 to 5, one end side of the protective cover 26 is attached to the boss portion 24 of the rod 23 by using the cover attaching member 27 composed of the abutting plate 28 and the movable plate 29, and free. The other end side of the protective cover 26 that is the end can be movably supported on the tube 22 by using a cover slide mechanism 32 including the clamp members 33 and 34 and the guide plate 37.

  Thus, according to the present embodiment, the cover mounting member 27 provided on one end side of the protective cover 26 sandwiches the boss portion 24 of the rod 23 from the front and rear of the rod 23 in the axial direction, thereby providing a cover mounting member. Since one end side of the protective cover 26 can be easily attached to the rod 23 in a state where the 27 is fixed to the boss portion 24, the workability of attaching and removing the protective cover 26 can be improved.

  In addition, since it is not necessary to provide a screw seat for attaching the protective cover, it is not necessary to prepare two types of cylinder devices according to the necessity of the protective cover 26, and the number of parts can be reduced and parts management is simplified. Can also contribute.

  Further, in the present embodiment, the cover mounting member 27 is configured by the contact plate 28 provided on one end side of the protective cover 26 and the movable plate 29 that is movable with respect to the corresponding contact plate 28. With the contact plate 28 in contact with the outer peripheral surface 24C of the boss portion 24 on the opposite side of the rod, the movable plate 29 is moved closer to and away from the contact plate 28 and the outer peripheral surface 24B of the boss portion 24 on the rod side. , The boss portion 24 of the rod 23 can be securely sandwiched between the contact plate 28 and the movable plate 29. Therefore, for example, even when the shape (outside diameter dimension) of the boss portion 24 changes depending on the type of the cylinder device, the boss portion 24 is firmly sandwiched between the contact plate 28 and the movable plate 29, so that the protective cover 26 One end side can be securely attached to the rod 23.

  In the present embodiment, a fitting hole 28E is provided on the tip side of the contact plate 28, and the fitting hole 28E and the annular protrusion 28F are fitted to a nipple guard 24F provided on the boss portion 24 of the rod 23. In the combined state, the front end side of the contact plate 28 is configured to contact the outer peripheral surface 24 </ b> C on the opposite side of the boss portion 24. Accordingly, the protective cover 26 is prevented from being displaced in a direction perpendicular to the axial direction of the rod 23 in a state where the boss portion 24 is sandwiched between the contact plate 28 and the movable plate 29, and the protective cover 26 is appropriately set. Since it can be held in the posture, the rod 23 can be reliably protected by the protective cover 26.

  Furthermore, according to the present embodiment, the cover slide mechanism 32 including the clamp members 33 and 34 and the guide plate 37 is provided on one end side of the tube 22, and the free end of the protective cover 26 is slid by the cover slide mechanism 32. By supporting the rod 23 in a possible manner, the protective cover 26 can be smoothly moved following the expansion and contraction of the rod 23, and the rod 23 can be reliably protected by the protective cover 26.

  In the above-described embodiment, the case where the contact plate 28 made of a member different from the protective cover 26 is fixed to one end of the protective cover 26 is illustrated (see FIG. 9). However, the present invention is not limited to this. For example, the protective cover 41 may be configured as a modification shown in FIG.

  In other words, the protective cover 41 according to the modified example includes an upper plate portion 41A, a groove portion 41B, and a protruding portion 41C, and a contact plate 41D is integrally formed on one end side of the upper plate portion 41A. The contact plate 41D of the protective cover 41 may be provided with a long hole 41E, a fitting hole 41F, and an annular protrusion 41G.

  Further, in the above-described embodiment, the boss portion 24 in which the nipple guard 24F protrudes from the outer peripheral surface 24C on the opposite rod side is used, and the fitting hole 28E and the annular protrusion 28F provided in the flat contact plate 28 are formed. The case where it fits into the nipple guard 24F of the boss | hub part 24 is illustrated. However, the present invention is not limited to this. For example, the contact plate 42 may be configured as in the modification shown in FIG.

  That is, the contact plate 42 according to the modification can be applied to the boss portion 24 'having the pin insertion hole 24A' and not having the nipple guard, and has a wide width portion 42A, a narrow width portion 42B, and a reinforcing plate 42C. The front end side of the narrow portion 42B is configured as an arc surface corresponding to the outer peripheral surface of the boss portion 24 '. Then, the distal end side of the narrow width portion 42B that is an arc surface is brought into contact with the outer peripheral surface 24C ′ on the opposite rod side of the boss portion 24 ′, and the movable plate 29 is inserted into the rod side of the boss portion 24 ′ via the elastic body 31. The boss portion 24 ′ can be reliably sandwiched between the contact plate 42 and the movable plate 29 by contacting the outer peripheral surface 24 B ′.

  Furthermore, in embodiment mentioned above, the case where the cylinder apparatus is applied to the bucket cylinder 21 of the hydraulic excavator 1 is illustrated. However, the present invention is not limited to the bucket cylinder, and may be applied to, for example, the boom cylinder 11, the offset cylinder 12, the arm cylinder 13, etc. of the hydraulic excavator 1. The present invention can be widely applied to cylinder devices mounted on construction machines.

1 is a front view showing a hydraulic excavator to which a cylinder device according to an embodiment of the present invention is applied. It is a front view which shows the bucket cylinder in FIG. 1 alone. It is a partially broken front view which expands and shows the rod, protective cover, etc. in FIG. It is the top view which looked at the rod, the protective cover, etc. from the arrow IV-IV direction in FIG. It is sectional drawing which looked at the rod, the protective cover, the cover attachment member, etc. from the arrow VV direction in FIG. FIG. 6 is an enlarged cross-sectional view of the main parts showing the main parts such as a boss part, a contact plate, and a movable plate in FIG. 5 in an enlarged manner. It is an expanded sectional view which looked at the boss | hub part, the contact plate, the movable plate, etc. from the arrow VII-VII direction in FIG. It is an expanded sectional view which looked at the protective cover, the tube, the cover slide mechanism, etc. from the arrow VIII-VIII direction in FIG. It is a disassembled perspective view which shows a protective cover, a contact plate, a movable plate, and a cover slide mechanism. It is a front view which shows the state which attaches the one end side of a protective cover to the boss | hub part of a rod using a cover attachment member. It is a front view which shows the state which supports the other end side of a protective cover using a cover slide mechanism. It is a disassembled perspective view similar to FIG. 9 which shows the modification of a protective cover. It is sectional drawing similar to FIG. 6 which shows the modification of a contact plate.

Explanation of symbols

21 Bucket cylinder (cylinder device)
22 Tube 23 Rod 24, 24 'Boss part 24B, 24B' Rod side outer surface 24C, 24C 'Non-rod side outer surface 24E Grease nipple 24F Nipple guard 26, 41 Protective cover 27 Cover mounting member 28, 41D, 42 Contact plate 28E, 41F Fitting hole 29 Movable plate 32 Cover slide mechanism

Claims (4)

A tube, a rod protruding from one end side of the tube so as to be extendable and having a boss part for pin coupling on the protruding end side, one end side being supported by the rod and the other end side being a free end to the tube In a cylinder device comprising a protective cover that is movably supported and protects the rod,
A cylinder device characterized in that a cover mounting member for mounting the protective cover to the rod is provided on one end side of the protective cover by sandwiching the boss portion of the rod from the front and rear in the axial direction.   The cover mounting member is provided on one end side of the protective cover and abuts against the outer peripheral surface of the boss portion on the opposite side of the rod, and the outer periphery of the boss portion on the rod side is movable with respect to the corresponding contact plate. The cylinder device according to claim 1, wherein the cylinder device is configured by a movable plate that sandwiches the boss portion with the contact plate by contacting the surface. On the boss portion of the rod, a cylindrical nipple guard is provided so as to surround the periphery of the nipple for greasing,
The cylinder device according to claim 2, wherein the contact plate of the cover mounting member is provided with a fitting hole that fits into the nipple guard.   4. The cylinder device according to claim 1, 2, or 3, wherein a cover slide mechanism that slidably supports the protective cover according to expansion and contraction of the rod is provided on one end side of the tube.

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