9 Hydraulic Cylinder
9
a Cylinder Tube
9
b Cylinder Rod
30 Protection Device
31 Slide Guide
32 Guard Member
33 Slider
34 Support Portion
35 Pivot Shaft
36 Bush
37 Mount Stay
38 Mount Seat
40 Cushion Part
A mode for carrying out the invention will be described.
A backhoe serving as an embodiment of an excavation vehicle equipped with a protection device according to the invention. Referring to
A boom bracket 12 is laterally rotatably attached onto a front end portion of turning frame 2, and a boom 6 is vertically rotatably supported at a bottom end portion thereof onto boom bracket 12. Boom 6 is substantially doglegged so as to have a forward extended portion from its intermediate bent portion. An arm 5 is rotatably supported on a top portion of boom 6, and a bucket 4 serving as a working attachment is rotatably supported on a tip portion of arm 5. Boom 6, arm 5, bucket 4 and others constitute working device 7.
Boom cylinder 11 is actuated for rotating boom 6, arm cylinder 10 for rotating arm 5, and bucket cylinder 9 for rotating bucket 4. Boom cylinder 11, arm cylinder 10 and bucket cylinder 9 are hydraulic cylinders. Hydraulic pressure control lever 21, the pedal or another operation device disposed in driver's control section 15 is operated for switching a corresponding pilot valve so as to control a corresponding main valve (directive control valve) for supplying pressure oil from a hydraulic pump disposed in bonnet 14 on turning frame 2 to the corresponding hydraulic cylinder through hydraulic pressure hoses, thereby telescoping or rotating the corresponding unit.
A cylinder protection device 30 according to the invention will be described. In the present embodiment, only representative protection device 30 for bucket cylinder (hereinafter, referred to as “hydraulic cylinder”) 9 will be described on the assumption that it is adaptable for the other hydraulic cylinders.
As shown in
Guard member 32 is a flat plate made of spring steel, as shown in
Further, the elastically deformable flat plate of guard member 32 is a commercially available inexpensive member which can be easily cut and bent to form later-discussed notches 32a and pivotal portion 32b. Moreover, when guard member 32 is pressed and elastically deformed by an obstacle, guard member 32 contacts piston rod 9b in a surface or a line, thereby scarcely damaging piston rod 9b. Due to the rigidity of piston rod 9b required for its own work, guard member 32 has a sufficient rigidity against radial stress. To further reduce the possibility of damaging piston rod 9b, a cushion member may be applied onto a back surface of guard member 32 facing piston rod 9b. Rubber, foamed resin, elastic synthetic resin or another material serves as the cushion member. A surface of the cushion member is water repellent and smooth so as to avoid mud, dust or the like. When guard member 32 is pressed by an obstacle and abuts against piston rod 9b, the cushion member and guard member 32 absorb a shock due to their elasticity, so as to prevent the surface of piston rod 9b from being damaged.
Guard member 32 has a longitudinal length that is substantially equal to the longitudinal length of cylinder tube 9a. Guard member 32 has a width that is smaller (may be larger) than the width (diameter) of cylinder tube 9a and is larger than the width (diameter) of piston rod 9b. Therefore, during the telescopic movement of the hydraulic cylinder, guard member 32 synchronously slides so as to constantly cover the exposed side of piston rod 9b, thereby protecting piston rod 9b from obstacles.
The end portion of guard member 32 to be fitted into slide guide 31 is referred to as a base end portion of guard member 32. As shown in
The heights of sliders 33 match with heights of respective inner sides of rail-shaped portions of slide guide 31. Sliders 33 fitted to respective notches 32a have a width therebetween that is equal to the inner width of slide guide 31. Sliders 33 are made of material, such as synthetic resin, which resists abrasion and shock and is elastically deformable.
Notches 32a are easily formed by punching, cutting or other means. Sliders 33 interposed between guard member 32 and slider guide 31 prevent guard member 32 from directly contacting slide guide 31. Therefore, guard member 32 can silently and smoothly slide in slide guide 31. Even if slide guide 31 touches an obstacle and is partly plastically deformed, slider 33 can be elastically deformed during its passing through the plastically deformed portion of slide guide 31 so as to ensure the telescopic movement of guard member 32.
As shown in
In this regard, if the tips of piston rod 9b and guard member 32 were solidly joined to each other by a bolt or the like, an obstacle contacting guard member 32 would cause a stress concentrated on the joint portion of guard member 32 so as to bend, i.e., plastically deform guard member 32. The plastically deformed guard member 32 cannot be disposed in parallel to slide guide 31, so that, during the telescopic movement of the hydraulic cylinder, an unfitting force occurs in the mutual slidable fitting portions of guard member 32 and slide guide 31 so as to abrade one or both of guard member 32 and slide guide 31, or to make the telescopic movement of guard member 32 relative to slide guide 31 difficult. Ultimately, the plastic deformation of guard member 32 requires exchange of parts or another repairing work.
A cylindrical bush 36 is interposed between pivotal portion 32b and pivot shaft 35. Bush 36 is made of rubber, synthetic resin or the like, and is provide for smoothly rotating guard member 32 relative to pivot shaft 35. Due to bush 36, the noisy rubbing of metals is prevented between pivotal portion 32b and pivot shaft 35 during the rotation of guard member 32 or during the slide of guard member 32, thereby silencing the rotation and slide of guard member 32.
As shown in
Substantially U-like shaped support portion 34 has opposite side plates formed with respective slots 34a for supporting pivot shaft 35. Slots 34a are extended perpendicular to the axial direction of piston rod 9a. In other words, when guard member 32 is attached to support portion 34, slots 34a are disposed to extend perpendicular to the surface of guard member 32. When the protection device is provided on another hydraulic cylinder having a different size, a distance of slide guide 31 from the center axis of the hydraulic cylinder becomes different. Slots 34a provided in support portion 34 on the boss portion of the piston rod absorbs the difference of distance of slide guide 31 from the center axis of the hydraulic cylinder. Consequently, the protection device can adjust its distance from the center axis of the hydraulic cylinder so as to constantly dispose guard member 32 in parallel to the center axis of the hydraulic cylinder, thereby preventing guard member 32 from being rubbed against the hydraulic cylinder during their telescopic movement. Further, when guard member 32 contacts an obstacle, the tip of guard member 32 slides along slots 34a so as to reduce the deformation of the mutual connection portions of guard member 32 and support portion 34, thereby improving durability of guard member 32.
As shown in
A mount portion 31a on one end (base end) of slide guide 31 is fastened to an outer peripheral surface of a boss portion 9e on a base end (head end) of the hydraulic cylinder through a bolt or another fastening member. Mount portion 31a on the one end of slide guide 31 is vertically flattened so as to have a small thickness, thereby preventing guard member 32 from passing therethrough. Mount portion 31a is bored at the lateral middle portion thereof by a fixture hole 31. The bolt or another fastening member is inserted into fixture hole 31b so as to be screwed into the outer peripheral surface of boss portion 9e. Slide guide 31 is provided at the other end thereof with an opening, which is widened toward the cylinder tube (downward) so as to easily receive guard member 32.
A mount portion on the other end of slide guide 31 includes a pair of mount stays 37 fixed onto its opposite sides. A pair of mount seats 38 are fixed on an outer peripheral surface of cylinder tube 9a, and are adapted to be fastened to respective mount stays 37 through respective bolts or the like. Mount stays 37 fixed on opposite sides of slide guide 31 are arranged downward and outward in lateral opposite directions, i.e., like knitted brows, as shown in
Due to slots 37a having the function of absorbing the size differences among hydraulic cylinders, for example, between the bucket cylinder and the arm cylinder, common mount stays 37 can be mounted onto any of the hydraulic cylinders having different sizes, thereby reducing costs.
As shown in
Mount seats 38, fixed onto the outer peripheral surface of he cylinder tube 9a by welding or the like, are located apart from a cushion part 40 disposed in a rod side chamber of hydraulic cylinder 9 adjacent to a rod side cap 39, so that mount seats 38 are nearer to the base end of the cylinder than cushion part 40. Consequently, in the cylinder, a cushioning mechanism is disposed at its telescopic stroke end part, so that the cushioning mechanism cushions the piston when the piston abuts against the cap at its stroke end.
In this cushioning mechanism of the cylinder, a hermetic space is ensured between the cap and the piston adjacent to the stroke end thereof so that, when the piston reaches the stroke end, the hydraulic pressure in the hermetic chamber is compressed so as to function as a cushion, thereby squeezing oil. In this embodiment, the hermetic space is disposed in the rod side chamber so as to serve as cushion part 40. When piston 9d reaches the rod side end, the pressure in the hermetic space is increased so as to expand and deform cylinder tube 9a. If mount seats 38 were joined to an outer peripheral surface of cushion part 40 by welding, the welded portion of the mount seat would be concentrically stressed so as to be damaged. Therefore, in this embodiment, mount seats 38 are disposed at the position apart from cushion part 40. It may be noticed that mount stays 38 are attached to the outer peripheral surface of cylinder tube 9a at the position corresponding to rod side cap 39 apart from cushion part 40. However, the portion of cylinder tube 9a corresponding to rod side cap 39 may be subjected to heat deformation caused by welding mount seats 38 thereto so as to make a gap from mount seat 38. In this consideration, mount seat 38 is offset from cushion part 40 toward the base end (bottom end) of the cylinder.
In this way, the outer peripheral surface of the cylinder tube on the end toward the piston rod, onto which slide guide 31 is connected, is offset from cushion part 40 toward the base end of the cylinder tube. Therefore, even if cushion part 40 expands when the piston reaches its stroke end, the welded portions of mount seats 38 are prevented from being deformed, and slide guide 31 is prevented from being deviated, thereby surely guiding guard member 32.
The invention relates a protection device for a hydraulic cylinder provided to a working vehicle such as a backhoe or a loader. Especially, the protection device prevents a rod of the hydraulic cylinder from being damaged.
Number | Date | Country | Kind |
---|---|---|---|
2004-195835 | Jul 2004 | JP | national |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/JP05/11564 | 6/23/2005 | WO | 00 | 10/10/2007 |