JP2008151321A - Cylinder protector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To further improve the protecting function of a piston rod not to give nick and deformation to the piston rod of a cylinder due to collision. <P>SOLUTION: This cylinder protector 20 comprises an exterior protecting pipe 21 and a protecting pipe mounting ring 22, and a guide member 23. The protecting pipe mounting ring 22 is provided on a mounting part 14 connected to the front end of the piston rod 12, and the exterior protecting pipe 21 is connected at one end to the protecting pipe mounting ring 22 and provided extending to the side of a cylinder tube 11. A guide member 23 is mounted on the side of a rod delivery part 16 of the cylinder tube 11 for slidingly guiding the exterior protecting pipe 21. The exterior protecting pipe 21 is long enough to cover the outer face of the guide member 23 even when the hydraulic cylinder 10 is in a most elongating condition. Between the inner face of the exterior protecting pipe 21 and the outer face of the piston rod 12, an almost equal space is formed all over the whole length and periphery. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a cylinder protector for protecting a piston rod that is mounted on a cylinder provided in a hydraulic working machine or the like and protrudes from a cylinder tube.

  As a hydraulic industrial machine that operates in the field, for example, a hydraulic excavator includes a front working machine that performs work such as excavation of earth and sand, and the operation of the front working machine is performed by a hydraulic cylinder. The hydraulic cylinder is provided so that the piston rod protrudes from the cylinder tube. By supplying and discharging hydraulic pressure into the cylinder tube, the piston rod is expanded and contracted, and a member such as a bucket connected thereto is driven. The

  A hydraulic excavator is used for excavation of soil and sand in the field. Foreign matter such as dust adheres to the hydraulic cylinder that drives the front work machine, and can collide with flying objects such as rocks and structures such as concrete. There is sex. In particular, if the piston rod of a hydraulic cylinder expands and contracts with dust or the like attached, there is a risk that fine particles may enter the cylinder tube, and the impact of the piston rod on the surface of the piston rod may be damaged. is there.

Therefore, for example, Patent Document 1 discloses a configuration in which a protective member for protecting the piston rod is provided in the hydraulic cylinder. This known protective member is a stretchable protective cover, and this protective cover is composed of a flexible member having a shape such as a cylinder whose one end is fixed to the tip of the piston rod and the other end is fixed to the cylinder tube. ing. This flexible member expands and contracts following the expansion and contraction of the cylinder, and always protects the piston rod so as to cover it in the operating state of the cylinder.
JP 2001-241406 A

  By using the protective cover of Patent Document 1, foreign matter such as dust does not adhere to the piston rod, and solid objects such as rock do not collide directly, and there is an advantage that the cylinder can be effectively protected. However, since the protective cover is composed of a flexible member, there is a limit to the protection function of the piston rod, and even in harsh work sites where rocks or concrete fragments fly frequently, even if the protective cover is Even from the top, it is not possible to completely prevent a dent from being generated by a collision object or from being deformed by an impact. Then, when a dent or deformation occurs on the outer surface of the piston rod, the smooth operation is hindered, and inconveniences such as leakage of hydraulic oil in the cylinder tube occur. In addition, the protective cover does not have a sealed structure, and cannot prevent the liquid or the like that rusts or corrodes the piston rod surface from entering.

  The present invention has been made in view of the above points. The object of the present invention is to provide a higher protection function of the piston rod so that the piston rod of the cylinder is not dented or deformed by a collision object. There is to do.

  In order to achieve the above-mentioned object, the present invention is attached to a cylinder having a cylinder tube and a piston rod led out from the cylinder tube to protect a lead-out portion of the piston rod from the cylinder tube. A cylinder protector, which is connected to the tip of the piston rod and is composed of a hard cylinder that is mounted so as to cover the piston rod, and is mounted on the outer periphery of the cylinder tube, The exterior protective tube is characterized in that it has a length having an overlap portion with respect to the guide member even when the piston rod is fully extended.

  There are various types of cylinders such as hydraulic cylinders and pneumatic cylinders, and examples of machines on which the cylinders are mounted include various industrial machines including construction machines and machine tools. The cylinder protector according to the present invention can be applied to any cylinder, but a piston in a cylinder provided in a machine operating under severe conditions such as a construction machine that may collide with flying objects or structures. It is particularly preferably used as a rod protection member.

  The exterior protection tube is composed of a hard cylinder, and covers the entire circumference of the piston rod through a predetermined space in the entire stroke range of the cylinder. For example, when a projectile such as rock collides with a cylinder, or when a cylinder collides with a structure, an impact is applied to the outer protective tube, but the impact is not applied to the piston rod. Even if an impact is applied, the impact can be effectively reduced. In order to cope with an impact acting from any direction, the outer protective tube and the piston rod are held so as to have a substantially uniform distance over the entire circumference. For this purpose, the part of the outer protective tube whose one end is fixed to the piston rod covers the cylinder tube is slidably supported by the guide member attached to the cylinder tube, and is thereby derived from the cylinder tube of the piston rod. The distance between the inner surface of the outer protective tube and the inner surface of the outer protective tube at the portion being held is substantially constant over the entire circumference.

  The outer protective tube can be formed of metal, ceramic, synthetic resin, etc., and a synthetic resin material that is particularly lightweight and has high strength is suitable. Further, a synthetic resin material that is excellent in impact resistance and shock-absorbing properties and has high elastic resilience is more desirable. When it collides with an object, it is not easily damaged by the impact, and the impact is buffered so that a large impact does not act on the piston rod, and when the load is released, it is restored smoothly and elastically A material that does this is most desirable. If the outer protective tube is made strong enough to withstand an extremely large impact, the thickness of the outer protective tube becomes large and expensive. There is a limit to the strength of the outer protective tube, and when an external force exceeding the limit is applied, it is desirable that the outer protective tube is not permanently deformed, but rather the outer protective tube is broken to absorb the impact. If the outer protective tube is damaged, the protection function of the piston rod is lost, but the situation where the expansion and contraction operation of the cylinder becomes impossible is avoided.

  Although it depends on the operating conditions of the cylinder, it is convenient that the outer protective tube can be appropriately replaced as a consumable since it may be damaged. Therefore, a protective tube mounting member made of an annular member having a predetermined width and thickness is fixed to the tip of the piston rod, and an exterior protective tube is detachably attached to the protective tube mounting member. it can. For fixing the exterior protective tube to the protective tube mounting ring, means such as concave-convex engagement, adhesion, screwing, and screwing can be employed. Similarly, in order to make the guide member replaceable, a spacer may be attached to the outer peripheral surface of the cylinder tube, and the guide member may be detachably fixed to the spacer. If the outer protective tube and guide member do not require replacement, the protective tube mounting member and spacer can be provided integrally with the outer protective tube and guide member, and they are directly fixed to the cylinder so that they cannot be separated. May be.

  The protective tube mounting member can be composed of a metal or synthetic resin mounting ring, and by adjusting these thickness dimensions as appropriate, an appropriate distance between the inner peripheral surface of the outer protective tube and the outer peripheral surface of the piston rod can be obtained. Can be spaced. Further, for example, when there is a connection pipe to the rod side chamber of the cylinder tube attached to the cylinder tube, the guide member can be mounted so as to cover these protrusions. Spacers are provided to accommodate such protrusions. Therefore, the guide member may be directly fixed to the cylinder tube if there is no protrusion on the outer periphery of the cylinder tube.

  As described above, since the outer protective tube may be damaged or damaged by collision with an object or the like, it is preferable to make it easy to replace the outer protective tube, particularly in a construction machine or the like, with a cylinder mounted on the machine. It is very convenient to be able to replace it without removing it. For this purpose, a cylindrical outer protective tube is divided in half so as to penetrate in the axial direction, so that it is constituted by a two-divided arc-shaped protective tube piece, and an appropriate fastener is fixed to the outer peripheral portion thereof. Can be combined into a cylindrical shape. Fastening portions of the fastener are at least at both ends, and more preferably, one or more fastening portions of the fastener are provided in the middle.

  A guide member is provided in order to keep the space | interval of an exterior protection tube and a piston rod appropriate in the full stroke range of a cylinder. From this point of view, the guide member can be of a minimum width provided near the end of the cylinder tube on the rod lead-out side. In order to move the guide tube, the guide member has a length for sliding and guiding the outer protective tube over the entire stroke of the cylinder. If the length of the guide member is limited, when the cylinder is in its fully contracted state, a considerable part of the outer protective tube will be in a free state if it is left as it is, and the strength will be weak, and sliding with the guide member will occur. The smoothness may also be impaired. Accordingly, when the guide member is mounted in the vicinity of the rod outlet side end of the cylinder tube, it engages with the outer surface of the cylinder tube so that it can slide smoothly with the inner surface of the outer end of the outer tube. As a bearing, a rolling member made of a sliding member, a steel ball, or a roller may be mounted. A plurality of these bearings or rolling elements are provided at equal intervals in the circumferential direction, and the stability of the outer protective tube is further increased when the number of the bearings or rolling elements is increased.

  For example, a cylinder attached to a machine for performing dredging, reclamation, etc. on rivers and beaches is immersed in sludge or seawater, which may cause water to adhere to the surface of the piston rod and cause rusting or corrosion. There is. Therefore, for the cylinder used under such circumstances, the interior of the exterior protective tube can be held in a liquid-tight structure so that the surface of the piston rod is not soiled. For example, a configuration in which a seal member is interposed between the outer protective tube and the guide member, or a bellows-like sealing member that can expand and contract between the base end portion of the outer protective tube and the outer surface of the cylinder tube is adopted. Can do. In the case of such a sealed structure, the internal volume of the exterior protective tube changes according to the expansion / contraction operation of the cylinder, and the pressure fluctuates. In order to prevent or suppress pressure fluctuations in the outer protective tube, one end of the air pipe is opened in the outer protective tube, the air pipe is inserted into the guide member, and extends to a position where it is not immersed in mud or seawater. The other end may be opened to the atmosphere.

  The exterior protection tube can effectively protect the piston rod that expands and contracts with respect to the cylinder tube, and can prevent the outer surface of the piston rod from being damaged or deformed.

    Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, FIG. 1 shows a configuration of a hydraulic excavator as an example of a machine equipped with a cylinder to which a cylinder protector of the present invention is attached. In the figure, 1 is a lower traveling body of a hydraulic excavator, and 2 is an upper swing body. A front work machine 3 is mounted on the upper swing body 2, and the front work machine 3 includes a boom 4, an arm 5, and a bucket 6 as a front attachment. By operating the front work machine 3, Work such as excavation of earth and sand is performed. The boom 4, the arm 5 and the bucket 6 constituting the front work machine 3 are driven by hydraulic cylinders 10a, 10b and 10c, respectively (in the following, the reference numeral 10 is used to collectively refer to the hydraulic cylinders of the respective parts). The

  2 and 3 show the configuration of the hydraulic cylinder 10 with the cylinder protector 20 attached thereto. In the figure, 11 is a cylinder tube and 12 is a piston rod. As is well known, the hydraulic cylinder 10 is connected to a piston (not shown) provided in the cylinder tube 11 of the piston rod 12, and the inside of the cylinder tube 11 is divided into two chambers, a rod side chamber and a bottom side chamber. The piston rod 12 is contracted and expanded by supply and discharge of pressure oil to and from these chambers. FIG. 2 shows a contracted state of the hydraulic cylinder 10, and FIG. 3 shows an extended state.

  The hydraulic cylinder 10 is connected between one member constituting the front work machine 3 and the other member. For this purpose, mounting portions 13 and 14 through which pins are inserted are provided at the base end portion of the cylinder tube 11, that is, the end portion on the opposite side to the rod lead-out side and the tip end portion of the piston rod 12, respectively. A mounting portion 13 of the cylinder tube 11 is provided integrally with the head cover 15, and a rod lead-out portion 16 is provided at the other end of the cylinder tube 11. The head cover 15 and the rod outlet 16 are connected to hydraulic pipes 17 for supplying and discharging hydraulic pressure to and from the two chambers in the cylinder tube 11. In these drawings, only the hydraulic piping 17 on the rod outlet 16 side is shown, and the hydraulic piping on the head cover 15 side does not appear on the drawings.

  The cylinder protector 20 is generally composed of an exterior protection tube 21, a protection tube attachment ring 22 as a protection tube attachment member, and a guide member 23. The protective tube mounting ring 22 is fixedly provided to the mounting portion 14 connected to the tip of the piston rod 12 by bonding, welding, or the like. When the protective tube mounting ring 22 is formed of metal, several portions are provided. It can be fixed to the mounting portion 14 by spot welding. And the part at the one end side of the exterior protection tube 21 is connected to this protection tube attachment ring 22 so that attachment or detachment is possible by means, such as screwing. The outer protective tube 21 extends from the connecting portion to the protective tube mounting ring 22 to the cylinder tube 11 side. The outer protective tube 21 is made of a hard synthetic resin having a high strength formed in a cylindrical shape, and more preferably, impact resistance such as polystyrene resin, ABS resin, EVA resin, polycarbonate, and the like. It is made of a synthetic resin material that is excellent in elasticity and highly elastic.

  On the other hand, the guide member 23 is made of a ring-shaped member and has a predetermined width dimension on the rod outlet portion 16 side of the cylinder tube 11. The guide member 23 is made of metal, synthetic resin, or the like, and is fixed to the rod lead-out portion 16 or the distal end portion of the cylinder tube 11 by means such as welding or adhesion. The hydraulic piping 17 connected to the rod lead-out portion 16 extends to the proximal end side of the cylinder tube 11 so as to penetrate the guide member 23. Therefore, when attaching the guide member 23, it is desirable to provide at least the insertion portion of the hydraulic pipe 17 or to divide it into two parts.

  The guide member 23 is for slidingly guiding the outer protective tube 21, and thus the outer diameter of the guide member 23 is slightly smaller than the inner diameter of the outer protective tube 21. Further, the outer protective tube 21 has a length that covers the outer surface of the guide member 23 even in the most extended state of the hydraulic cylinder 10 illustrated in FIG. 3. The distance between the inner surface of the exterior protection tube 21 and the outer surface of the piston rod 12 is substantially uniform over the entire length and the entire circumference. Further, in this way, the long exterior protection tube 21 is in contact with the guide member 23 only in a small portion on the distal end side when the hydraulic cylinder 10 shown in FIG. In order to stabilize the proximal end portion of the cylinder 21, the cylinder tube is provided on the inner surface on the open end side of the outer protective tube 21 at a plurality of locations in the circumferential direction, specifically at four locations as shown in FIG. A bearing 24 is mounted on the outer peripheral surface of 11 for smooth sliding without resistance. As a result, the end portion of the outer protective tube 21 does not become free, and the axis is not shaken. As a result, when the hydraulic cylinder 10 is operated, the cylinder protector 20 attached to the hydraulic cylinder 10 can move smoothly without causing resistance, and the exterior protective tube 21 is connected to the protective tube mounting ring 22. A large load is not applied.

  The excavator excavates earth and sand, and rocks may jump up during this work, and even when the work such as the dismantling of the structure is performed, the fragments of concrete are scattered or collide with the structure. Operating under mild conditions. Therefore, the flying cylinders such as rocks and structures collide with the hydraulic cylinder 10, particularly the bucket hydraulic cylinder that drives the bucket 6, and there is a risk of damage or deformation due to the impact. The cylinder protector 20 configured as described above is attached to the hydraulic cylinder 10 so that when the piston rod 12 is led out from the cylinder tube 11, the outer surface thereof is not damaged, and dents or deformations are not generated. Protected.

  The exterior protective tube 21 constituting the cylinder protector 20 moves following the expansion and contraction of the piston rod 12 and completely covers the piston rod 12 even when the hydraulic cylinder 10 shown in FIG. Therefore, an impact acts on the outer protective tube 21 when it collides with another object such as a flying object or a structure. Here, the exterior protective tube 21 is formed of a resin material having good impact resistance and shock-absorbing properties, and there is a predetermined gap between the exterior protective tube 21 and the piston rod 12. No impact is directly applied to the piston rod 12 at the time of collision with the object. When the impact on the exterior protective tube 21 is released, the exterior protective tube 21 is elastically restored.

  As described above, most of the impact due to the collision is absorbed by the exterior protection tube 21 or received by the exterior protection tube 21, so that the piston rod 12 is effectively protected. However, there is a limit to the impact absorption and repulsion force by the exterior protective tube 21. If the durability of the exterior protective tube 21 is made too high, it is not preferable in terms of increasing the thickness and weight. Therefore, when an extremely strong impact is applied, the exterior protective tube 21 is damaged. However, since the impact is primarily received by the outer protective tube 21, the impact acting on the piston rod 12 is remarkably mitigated, and a dent is generated on the surface of the piston rod 12, There is no deformation or damage.

  Even if the exterior protection tube 21 is damaged, the hydraulic cylinder 10 itself can operate. Therefore, even if the exterior protection tube 21 is damaged in the middle of work, the front work machine 3 is driven until it reaches a predetermined posture. be able to. Further, the damaged outer protective tube 21 can be removed from the hydraulic cylinder 10 and replaced with a new outer protective tube 21. Here, in order to allow the exterior protection tube 21 to be replaced without removing the hydraulic cylinder 10 while being incorporated in the front work machine 3, as shown in FIG. 5, the exterior protection tube 121 is directed in the axial direction. It is composed of arcuate protective tube pieces 121a and 121a that are divided into two halves. Then, both arc-shaped protective tube pieces 121a and 121a are joined to form a cylindrical shape, and a joined state is obtained by using a fastener 120 comprising an elastic band piece 120a composed of a metal band or the like and a tightening screw rod 120b. Hold. One or several fasteners 120 are attached to both ends and an intermediate portion.

  When the two-part type is used like the outer protective tube 121 of FIG. 5, as shown in FIG. 6, the outer peripheral surface of the protective tube mounting ring 122 for fixing the outer protective tube 121 is annular. , And an annular ridge 124 is formed at a contact portion of the exterior protective tube 121 with the protective tube mounting ring 122, and the annular ridge 124 is formed in the groove 123 of the protective tube mounting ring 122. It is also possible to configure so that the exterior protection tube 121 is fixed in a state where it is attached to the piston rod 12 of the hydraulic cylinder 10 by being engaged with each other. Further, the protective tube attaching ring 122 may be divided into two as in the case of the exterior protective tube 121.

  The protective device of the hydraulic cylinder 10 can prevent the piston rod 12 of the hydraulic cylinder from being damaged or deformed when it collides with another object. Since most of the piston rod 12 is covered, dust and the like can be prevented from adhering to the surface of the piston rod 12, and harmful substances can be prevented from adhering.

  However, the piston rod 12 is not completely sealed by the exterior protective tube 21. And in order to exhibit the function which prevents that fouling substances, such as a liquid, a viscous substance, a solid matter, etc. adhere to the surface of a piston rod, what is necessary is just to set it as the structure of 2nd Embodiment shown below. First, the importance of preventing the piston rod from fouling is more pronounced, for example, in the case of a hydraulic cylinder for driving the opening and closing of a clamshell bucket and is therefore preferably used as a cylinder protector for this type of hydraulic cylinder. .

  FIG. 7 shows the configuration of a hydraulic excavator equipped with a clamshell bucket. The hydraulic excavator itself is substantially the same as the configuration shown in FIG. 1, and members equivalent to those in FIG. 1 are denoted by the same reference numerals. An attachment attached to the front end of the front working machine 3 including the boom 4 and the arm 5 is a clamshell bucket 7. Unlike the standard bucket 6, the clamshell bucket 7 is used for excavating earth and sand in rivers, underwater, etc. for dredging.

  As shown in FIGS. 8 and 9, the clamshell bucket 7 has a pair of clamshells 30, 30. These clamshells 30 are pivotally supported by a drive plate 32 pivoted on a bracket 31 a of a support member 31. Has been. The support member 31 is connected to the tip of a piston rod 35 led out from a cylinder tube 34 of a hydraulic cylinder 33 for opening and closing. The base end portion of the cylinder tube 34 is connected to a connecting member 36, and the connecting member 36 is provided with an attachment portion 37 that is pivotally supported at the tip of the arm 5. As a result, the clamshell bucket 7 is assembled in a state suspended from the arm 5.

  FIG. 7 shows a state where dredging is performed using the clamshell bucket 7, that is, a state where excavation and removal of dredged sediment including sludge accumulated in the bottom of the water is performed in a river or a harbor. It is shown. At the time of excavation, as shown in FIG. 9, the clamshells 30, 30 are opened, and when the clamshell 30 comes into contact with the bottom of the water, the hydraulic cylinder 33 is operated, as shown in FIG. By closing the space between the clam shells 30 and 30, the soil is removed. Therefore, the hydraulic cylinder 33 is expanded and contracted in water.

  In order to prevent harmful substances such as muddy water and sludge from adhering to the piston rod 14 on the surface of the piston rod 35 constituting the hydraulic cylinder 33 in water, the cylinder protector 40 is sealed and protected. Here, the cylinder protector 40 protects the piston rod 35 from being contaminated, but as described in the first embodiment, the cylinder protector 40 is not so frequent as in the case of the standard earth and sand excavation work. However, there is a possibility of collision with an object, and the protection function against impact will be exhibited.

  As illustrated in FIGS. 10 to 12, the cylinder protector 40 includes a cylindrical guide member 41 and an exterior protective tube 42. Here, the guide member 41 and the exterior protective tube 42 are formed of a synthetic resin from the viewpoints of rust prevention, corrosion prevention, and the like. The guide member 41 is fixedly held on the cylinder tube 34 of the hydraulic cylinder 33. The cylinder tube 34 is connected to a hydraulic pipe 38 from the tip thereof, and the guide member 41 is mounted so as to cover the hydraulic pipe 38, and the guide member 41 is long. Instead of being directly fixed to the cylinder tube 34, spacers 43, 43 having a predetermined thickness are fixedly mounted at positions near both ends of the cylinder tube 34, and the guide member 41 is fixed on these spacers 43. . The hydraulic pipe 38 penetrates the spacer 43 in a close fitting state and extends to the side connected to the arm 5.

  The exterior protection tube 42 is connected to the tip of the piston rod 35. A support member 31 is connected to the piston rod 35, and a protective tube attachment ring 44 is fixed to the support member 31, and a distal end portion of the exterior protection tube 42 is fixed to the protection tube attachment ring 44. ing. The space between the protective tube mounting ring 44 and the support member 31 and the exterior protective tube 42 are liquid-tight. The exterior protection tube 42 extends toward the cylinder tube 34 and is slidably fitted to a guide member 41 attached to the cylinder tube 34.

  The exterior protection tube 42 maintains the fitted state with the guide member 41 over the entire stroke range of the hydraulic cylinder 33, that is, from the most contracted state shown in FIG. 10 to the most extended state shown in FIG. ing. An elastic seal member 45 formed in an annular shape is attached to the inner surface of the base end portion of the exterior protective tube 42 so as to be in pressure contact with the outer peripheral surface of the cylinder tube 34. As a result, the space between the inner surface of the exterior protection tube 42 and the outer surface of the guide member 41 is maintained in a sealed state even when the hydraulic cylinder 33 is expanded or contracted.

  With the above-described configuration, when the hydraulic cylinder 33 is operated, the portion of the piston rod 35 that is led out of the cylinder tube 34 is covered with the exterior protective tube 42 that constitutes the cylinder protector 40. Moreover, since one end side of the exterior protection tube 42 is connected to a protection tube mounting ring 44 fixed to the support member 31 and the other end is in contact with the guide member 41 via an elastic seal member 45, the piston rod 35 is always located in a sealed space. Therefore, the piston rod 35 is always kept clean even when excavation of mud and sand in the muddy water and seawater by the clamshell bucket 7, and there is no fear of fouling, rusting, corrosion, or the like.

  Thus, if the inside of the exterior protective tube 42 is sealed, when the hydraulic cylinder 33 operates and the piston rod 35 expands and contracts, the internal volume of the exterior protective tube 42 changes, and this Pressure fluctuations occur in the sealed space. In order to prevent or at least suppress this pressure fluctuation, an air pipe (not shown) is connected in the sealed space, this air pipe is extended to the arm 5 side together with the hydraulic pipe 38, and the other end is securely submerged. What is necessary is just to comprise so that it may open outside at this position.

  In order to hold liquid such as muddy water or seawater from the gap between the outer protective tube 42 and the guide member 41 in the space where the piston rod 35 is disposed, the elastic seal member 45 described above is used instead of the elastic seal member 45 described above. As shown in FIG. 5, the bellows-like sealing member 50 may be mounted between the end portion of the outer protection tube 42 and the position near the connecting portion of the cylinder tube 34 to the connecting member 31. The bellows-like sealing member 50 is composed of fastening bands 51, 51 attached to the exterior protection tube 42 and the cylinder tube 34, and a bellows 52 provided between the fastening bands 51, 51. Is formed of a flexible sheet.

  As a result, not only the piston rod 35 but also the entire hydraulic cylinder 33 is hermetically sealed, and protection from the contaminated liquid and the like is achieved. Moreover, since the internal volume changes according to the expansion and contraction of the bellows 52, an air pipe is connected to the bellows 52, and the other end of the air pipe is opened at a position not submerged. Can be expanded / contracted to a certain extent due to a change in internal pressure, so that the load due to pressure fluctuations in each part constituting the sealed space can be reduced.

1 is an overall configuration diagram of a hydraulic excavator as an example of a machine provided with a hydraulic cylinder to which a cylinder protector is attached. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a first embodiment of the present invention, and is a front view of a hydraulic cylinder when a cylinder protector shown in a cross-section is attached to a fully contracted state. FIG. 3 is a front view of main parts of the hydraulic cylinder when the hydraulic cylinder of FIG. It is AA sectional drawing of FIG. It is a front view of the state which showed the modification of the exterior protection pipe which comprises a cylinder protector, and was equipped with this cylinder protector on the hydraulic cylinder. It is a figure which shows the cross section of the front-end | tip part of the cylinder protector of FIG. FIG. 6 is a configuration explanatory view of a hydraulic excavator equipped with a clamshell bucket provided with another type of hydraulic cylinder to which a protector is attached. It is a front view of the clamshell bucket which made the clamshell closed with the hydraulic cylinder which equipped with the cylinder protector which shows the 2nd Embodiment of this invention. FIG. 9 is an operation explanatory view of FIG. 8 shown with the clamshell opened. It is principal part sectional drawing of FIG. It is BB sectional drawing of FIG. It is principal part sectional drawing of FIG. It is sectional drawing similar to FIG. 10 which shows the modification in the 2nd Embodiment of this invention.

Explanation of symbols

3 Front working machine 6 Bucket 7 Clamshell bucket 10, 33 Hydraulic cylinder 11, 34 Cylinder tube 12, 35 Piston rod 20, 40 Cylinder protector 21, 121 Exterior protective tube 22, 41, 122 Protective tube mounting ring 23, 43 Guide Member 24 Bearing 30 Clamshell 43 Spacer 44 Elastic seal member 50 Bellows-like sealing member 120 Fastener 121a Arc-shaped protective tube piece

Claims (7)

In a cylinder protector that is attached to a cylinder having a cylinder tube and a piston rod led out from the cylinder tube to protect the lead-out portion of the piston rod from the cylinder tube,
An outer protective tube made of a rigid cylinder connected to the tip of the piston rod and mounted to cover the piston rod;
It is mounted on the outer periphery of the cylinder tube, and comprises a guide member that slides and guides the inner surface of the outer protective tube,
The cylinder protector according to claim 1, wherein the outer protective tube has a length having an overlap portion with the guide member even when the piston rod is extended to the maximum. The cylinder protector according to claim 1, wherein a protection tube attachment member to which the exterior protection tube is detachably connected is provided at a tip of the piston rod. A connecting pipe connected to the rod side chamber of the cylinder tube is disposed along the outer peripheral surface of the cylinder tube, and the guide member is formed in a cylindrical shape and attached to the outer peripheral surface of the cylinder tube. The cylinder protector according to claim 1 or 2, wherein the cylinder protector is attached to the spacer so as to cover the cylinder tube and the connecting pipe. 4. The bearing according to claim 1, wherein a bearing that engages with an outer surface of the cylinder tube is provided at an end portion of the outer surface of the outer protection tube that is engaged with the cylinder tube. The cylinder protector described. The outer protection tube is composed of a pair of arc-shaped protection tube pieces divided in half in the axial direction, and both arc-shaped protection tube pieces are configured to be assembled into a cylindrical shape by fasteners fixed to the outer peripheral side. The cylinder protector in any one of Claim 1 thru | or 4. The cylinder protector according to any one of claims 1 to 4, wherein a seal member is interposed between the outer protective tube and the guide member. The cylinder protector according to any one of claims 1 to 4, wherein a bellows-like sealing member capable of expanding and contracting is provided between a base end portion of the exterior protection tube and an outer surface of the cylinder tube. .

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