Multistage hydraulic cylinder

Abstract

A multi-stage hydraulic cylinder includes: a fixed cylinder (2); at least one movable cylinder (3) extendable relative to the fixed cylinder (2); a piston rod (4) extendable relative to the movable cylinder (3); and an outer sleeve (5) fixed to the top of the piston rod (4); wherein a rod head (11) is welded to the top of the piston rod (4), a top plate (10) is welded to the top of the outer sleeve (5), a flange nut (12) is threadedly engaged with the rod head (11) and screwed to the top plate (10), and a locating pin (15) is installed between the flange nut (12) and the rod head (11) to prevent relative rotation between them. The connection strength and rigidity between the piston rod and the outer sleeve are improved, and loosening of the outer sleeve is prevented.

Description

Technical Field

[0001] This application relates to a multi-stage hydraulic cylinder for heavy-duty applications. Background Art

[0002] Multi-stage hydraulic cylinders are frequently used as actuating elements in various heavy-duty working applications. For example, unloading is achieved on dump trucks using heavy-duty multi-stage hydraulic cylinders. Dump trucks, also known as tipper trucks, are typical vehicles used for transporting materials (e.g., minerals). A dump truck typically consists of a frame to which a dump truck body, in the form of a square container with an open top, is pivotally mounted. A hydraulic cylinder is provided between the frame and the dump truck body; the piston rod of the cylinder can extend to pivot the dump truck body to an inclined unloading position, where the load can be emptied from the body. Afterward, the piston rod retracts to lower the dump truck body back onto the frame.

[0003] In current standard multi-stage hydraulic cylinders, a large nylon nut is used to directly connect the piston rod to the top plate of the outer sleeve. After long-term use, this nut is prone to loosening, leading to scratches on the outside of the cylinder. Summary of the Invention

[0004] This application aims to improve the overall strength and rigidity of multi-stage hydraulic cylinders and prevent the outer sleeve from loosening.

[0005] Therefore, according to one aspect of this application, a multi-stage hydraulic cylinder for heavy-duty applications, such as for dump trucks, is provided, comprising:

[0006] Fixed cylinder;

[0007] At least one movable cylinder that can extend relative to the fixed cylinder;

[0008] A piston rod that can extend relative to the movable cylinder; and

[0009] The outer sleeve is fixed to the top of the piston rod;

[0010] The piston rod has a rod head welded to its top end, and a top plate is welded to the top end of the outer sleeve. A flange nut is threadedly engaged with the rod head and is also connected to the top plate by a set of screws. A locating pin is installed between the flange nut and the rod head to prevent relative rotation between them.

[0011] In one embodiment, the rod head includes a flange, a lower end extending downward from the flange and welded to the top of the piston rod, a column extending upward from the flange, and a threaded section located above the column; and the flange nut includes a flange portion and a nut portion extending upward from the flange portion, the flange portion being fixed to the lower surface of the top plate by the set of screws, and the nut portion having a threaded hole portion that engages with the threaded section of the rod head.

[0012] In one embodiment, the locating pin passes through one of a set of through holes in the flange portion and is inserted into a locating hole in the flange.

[0013] In one embodiment, the set of screws engages with a set of screw holes in the flange portion, and the circumferential position of each through hole is set to be offset relative to the circumferential position of each screw hole, such that no through hole is located on a radial straight line passing through the center of any screw hole.

[0014] In one embodiment, a conical mating portion is provided between the flange nut and the rod head.

[0015] In one embodiment, the nut portion passes through the central hole of the top plate, and a nut and a corresponding sealing washer engage with the outer periphery of the nut portion to seal the gap between the nut portion and the top plate.

[0016] In one embodiment, each screw is equipped with an anti-loosening washer.

[0017] In one embodiment, the anti-loosening washer is a self-locking washer.

[0018] In one embodiment, the flange nut undergoes nitriding heat treatment.

[0019] In one embodiment, the lower portion of each outer wall of the piston rod and the movable cylinder is equipped with at least two axially spaced sliders.

[0020] In one embodiment, a pair of lower trunnions are mounted on the bottom of a fixed cylinder via an integral collar, the upper edge of which is welded to the outer wall of the fixed cylinder; the lower edge of the collar forms an inwardly turned flange that grips the bottom edge of the fixed cylinder; or, the lower edge of the collar is also welded to the outer wall of the fixed cylinder.

[0021] In the hydraulic cylinder according to this application, a flange nut is used to connect the piston rod and the outer sleeve. The flange nut has higher strength, is not easily deformed, and reduces the risk of loosening due to deformation of the top structure. When the flange nut is subjected to external force and generates torque in the disassembly direction, the locating pin can effectively limit the flange nut and prevent it from loosening, thereby improving the overall strength and rigidity of the heavy-duty hydraulic cylinder. Attached Figure Description

[0022] The embodiments of this application will now be described by way of example with reference to the accompanying drawings, in which:

[0023] Figure 1 This is a schematic diagram of a dump truck that uses a multi-stage hydraulic cylinder according to this application;

[0024] Figure 2 , Figure 3These are partial cross-sectional views taken at the top and bottom of the outer sleeve of a cylinder according to one embodiment of this application.

[0025] Figure 4 This is a partial sectional view taken at the bottom of the fixed cylinder barrel of the hydraulic cylinder in this application;

[0026] Figure 5 This is a partial sectional view of a modified example with the bottom of the fixed cylinder barrel;

[0027] Figure 6 This is a cross-sectional view of the top structure of the hydraulic cylinder of this application;

[0028] Figure 7 It is a cross-sectional view of the rod head in the hydraulic cylinder;

[0029] Figure 8 This is a cross-sectional view of the flange nut in the hydraulic cylinder;

[0030] Figure 9 This is a cross-sectional view of the top structure of a hydraulic cylinder according to another embodiment of this application;

[0031] Figure 10 This is a cross-sectional view of the top structure of a hydraulic cylinder according to another embodiment of this application;

[0032] Figure 11 This is a cross-sectional view of the slider in the hydraulic cylinder of this application. Detailed Implementation

[0033] This application generally relates to heavy-duty multi-stage hydraulic cylinders, which can be used in various heavy-duty working environments, such as metallurgy, mining equipment, coal mining machinery, petrochemical machinery, marine machinery, construction machinery and other engineering fields, as actuating elements.

[0034] A typical application of the multi-stage hydraulic cylinder of this application is in dump trucks, such as... Figure 1 The diagram illustrates the multi-stage hydraulic cylinder 1 according to this application. It mainly comprises: a fixed cylinder (base cylinder) 2; a plurality of movable cylinders 3 nested within the fixed cylinder 2 and extending sequentially; a piston rod 4 nested within the final movable cylinder 3 and extending from it; and an outer sleeve 5 supported by the piston rod 4. The bottom of the fixed cylinder 2 is equipped with a lower trunnion 6, and the bottom of the outer sleeve 5 is equipped with an upper trunnion 17. Here, the term "fixed cylinder 2" refers to a cylinder that is not telescopic like the movable cylinders 3. The fixed cylinder 2 is capable of rotation with the lower trunnion 6 as a fulcrum.

[0035] Hydraulic cylinder 1 is installed in the dump truck, lower trunnion 6 is pivotally mounted on frame 8, and upper trunnion 17 pivotally supports one longitudinal end (front end) of the box body 9. Figure 1In the middle, the hydraulic cylinder 1 is in a fully extended state, with each movable cylinder 3 extending out from the fixed cylinder 2 in sequence, and the piston rod 4 extending out from the last movable cylinder 3, so that the box body 9 is in an inclined self-unloading position.

[0036] When the multi-stage hydraulic cylinder 1 is in its fully retracted state, each movable cylinder 3 is located within the fixed cylinder 2, the piston rod 4 is located within the final movable cylinder 3, and the outer sleeve 5 is fitted over the fixed cylinder 2. This configuration and operation of the multi-stage hydraulic cylinder are well known in the art and will not be described in detail here.

[0037] Details of various parts of the multi-stage hydraulic cylinder 1 according to a feasible embodiment of this application are as follows: Figures 2 to 4 The image shows (multi-stage hydraulic cylinder 1 in the retracted position).

[0038] First, refer to Figure 2 The figure shows the structure at the top of the outer sleeve 5, where the top plate 10 is welded inside the outer sleeve 5. The piston rod 4 is hollow, and its upper end is assembled and welded to the lower end of the rod head 11. The flange nut 12 is connected to the rod head 11 via threaded engagement and to the top plate 10 via a set of screws 13. Each screw 13 is equipped with an anti-loosening washer 14. Furthermore, a locating pin 15 prevents the flange nut 12 from loosening due to relative rotation with the rod head 11.

[0039] In the retracted position of the multi-stage cylinder 1, each movable cylinder 3 surrounds the piston rod 4, and the fixed cylinder 2 surrounds each movable cylinder 3. A limit ring 16 is installed on the inner wall of each cylinder (movable cylinder 3 and fixed cylinder 2) near the upper end.

[0040] See Figure 3 The figure shows the structure at the bottom of the outer sleeve 5, where a pair of upper trunnions 17 are mounted around the bottom of the outer sleeve 5. These upper trunnions 17 extend in opposite radial directions. The upper trunnions 17 can be mounted to a moving part (e.g., driven by a multi-stage hydraulic cylinder 1). Figure 1 The corresponding structure of the housing 9) in the middle allows the multi-stage hydraulic cylinder 1 to drive the movement of the actuating component through the upper trunnion 17, while allowing the actuating component to rotate around the upper trunnion 17 relative to the outer sleeve 5.

[0041] See Figure 4 The figure shows the structure of the bottom of the fixed cylinder 2, wherein a pair of lower trunnions 18 are mounted around the bottom of the fixed cylinder 2. These lower trunnions 18 extend in opposite radial directions, parallel to the pair of upper trunnions 17. The lower trunnions 18 can be mounted to a support member (e.g., Figure 1 The corresponding structure of the frame 8) allows the entire multi-stage cylinder 1 to rotate (oscillate) relative to the support component around the lower trunnion 18.

[0042] Furthermore, the piston rod 4 and each movable cylinder 3 are each equipped with at least two axially spaced sliders 20 on their outer walls near their lower ends. When each movable cylinder 3 and piston rod 4 extends sequentially, the uppermost slider 20 will contact the limiting ring 16 on the inner wall of the facing cylinder, thereby limiting the maximum extension length of each movable cylinder 3 and piston rod 4. Compared to a scheme where each piston rod and each movable cylinder is equipped with only one slider, using at least two axially spaced sliders 20 increases the radial force-bearing points and force-bearing area of ​​the piston rod 4 and each movable cylinder 3, thereby increasing the rigidity of the cylinder and improving its resistance to eccentric loads.

[0043] Furthermore, the pair of lower trunnions 18 are mounted on the bottom of the fixed cylinder 2 via collars 19. The collars 19 surround the bottom of the fixed cylinder 2, and the upper edge of the collars 19 is welded to the outer wall of the fixed cylinder 2 via a ring weld A. The lower edge of the collars 19 forms an inward flange that grips the bottom edge of the fixed cylinder 2.

[0044] According to a modification, such as Figure 5 As shown, the upper edge of the collar 19 is welded to the outer wall of the fixed cylinder 2 through a ring weld A, while the lower edge is not formed. Figure 4 The flange shown is not welded to the outer wall of the fixed cylinder 2 via a ring weld B. In this modification, the connection strength of the lower trunnion 18 to the fixed cylinder 2 is improved by increasing the number of welds.

[0045] The following reference Figures 6 to 8 Describe the structural details at the top of the outer sleeve 5. Figure 6 In the middle, the top plate 10 is welded to the top of the outer sleeve 5 through a ring weld C at the outer periphery of its upper edge, and the upper end of the piston rod 4 is welded to the lower end of the rod head 11 through a ring weld D.

[0046] like Figure 7 As shown, the rod head 11 is a solid structure, including: a flat cylindrical lower end 21, which is suitable for insertion into the upper end of the piston rod 4; a flange 22 located above the lower end 21, the diameter of which is larger than that of the lower end 21; a column 23 extending upward from the center of the upper surface of the flange 22; and a threaded section 24 located above the column 23 and coaxial with the column 23.

[0047] The lower surface of the flange 22 forms a ramp, and correspondingly, the upper end of the piston rod 4 also forms a ramp, so that after the lower end 21 is inserted into the upper end of the piston rod 4, a weld bead for welding is generated between the lower surface of the flange 22 and the upper end of the piston rod 4.

[0048] At least one positioning hole 25 is formed on the flange 22, the positioning hole 25 extending downward from the upper surface of the flange 22 for insertion by the positioning pin 15.

[0049] like Figure 8 As shown, the flange nut 12 includes a flange portion 30 and a nut portion 31 extending upward from the center of the flange portion 30. The flange portion 30 has a plurality of threaded holes 32 distributed in a circumference, suitable for being screwed into by the threaded portion of a screw 13, and a plurality of through holes 33 distributed in a circumference, suitable for being passed through by a pin 15. The circular through holes 33 are located radially inside the circular threaded holes 32.

[0050] Optionally, the circumferential positions of each through hole 33 are offset relative to the circumferential positions of each threaded hole 32, such that no through hole 33 lies on a radial line passing through the center of any threaded hole 32. This configuration improves the crack resistance of the flange nut 12.

[0051] The flange nut 12 has an axially penetrating central hole, which includes a lower smooth hole portion 34 and an upper threaded hole portion 35. The smooth hole portion 34 is adapted to be inserted into and engaged with the post 23 of the rod head 11, and the threaded hole portion 35 is adapted to engage with the threaded section 24 of the rod head 11. The upper outer periphery of the nut portion 31 has a gripping surface 36 for a wrench to grip and tighten the nut portion 31.

[0052] It should be noted that the fit between the column 23 and the through hole portion 34 facilitates precise positioning between the rod head 11 and the flange nut 12. In a modified embodiment (not shown), the column 23 and the through hole portion 34 can be eliminated; that is, on the rod head 11, the threaded section 24 extends all the way to the flange 22, and in the flange nut 12, its entire central hole is formed by the threaded hole portion 35. This modified embodiment is simpler to manufacture and install.

[0053] Back Figure 6 The top plate 10 has a central hole for the nut portion 31 of the flange nut 12 to pass through, and a through hole for the screw shank of the screw 13 to pass through. During assembly, the rod head 11 is welded to the piston rod 4, the top plate 10 is welded to the top of the outer sleeve 5, and the rod head 11 engages with the threaded hole portion 35 via its threaded section 24, thus assembling the rod head 11 with the flange nut 12. Positioning of the rod head 11 and the flange nut 12 in the rotational direction is achieved using a locating pin 15. The nut portion 31 of the flange nut 12 is passed through the central hole of the top plate 10 from below, and the top plate 10 and the flange nut 12 are secured together using screws 13 (with anti-loosening washers 14). This completes the connection between the piston rod 4 and the outer sleeve 5.

[0054] According to this design, the rod head 11 is welded to the piston rod 4, and the top plate 10 is welded to the outer sleeve 5. The rod head 11 and the flange nut 12 are threaded together, and the rod head 11 and the flange nut 12 are positioned in the rotational direction by a locating pin 15. The top plate 10 and the flange nut 12 are fixed together by a screw 13 with an anti-loosening washer 14. This combined structure firmly connects the piston rod 4 to the outer sleeve 5, improving the connection strength and rigidity between them. When the flange nut 12 is subjected to external force and generates torque in the disassembly direction, the locating pin 15 can effectively limit the flange nut 12 and prevent it from loosening. The anti-loosening washer 14 can also prevent the flange nut 12 from loosening. In this way, the problem of the outer sleeve loosening is solved, fundamentally eliminating the cylinder external scoring failure caused by the sleeve loosening.

[0055] The anti-loosening washer 14 can be a Nord-Lock self-locking washer, which has a special anti-loosening structure, so that the outer sleeve 5 and the flange nut 12 have a better anti-loosening measure.

[0056] The flange nut 12 can be subjected to a nitriding heat treatment process, achieving a surface hardness of 320HV or even higher. This gives the flange nut 12 higher strength, making it less prone to deformation and reducing the risk of loosening due to deformation of the top structure.

[0057] In addition to the structural strength and stiffness provided by the outer sleeve and the enhanced anti-loosening ability mentioned above, for Figure 1 The application shown in this paper for dump trucks can also improve the stability of the dump truck. In the event of eccentric loading, the dual slider configuration of this application can provide more stress points, and the hydraulic cylinder can have better resistance to eccentric loading. When the hydraulic cylinder deflects due to eccentric loading of the dump truck body, the improved outer sleeve structure reduces the lateral angular displacement of the hydraulic cylinder caused by the eccentric loading force, and the probability of the outer sleeve rubbing against the base cylinder is greatly reduced.

[0058] for Figure 5 The double-weld fixing scheme for the lower trunnion shown increases the number of welds on the lower trunnion, reduces the stress on the welds, and improves the resistance of the base cylinder to eccentric loads.

[0059] Figure 9 A modified top structure of the outer sleeve 5 is shown, wherein a conical surface is formed on the bottom surface of the flange portion of the flange nut 12 around the lower end of the aperture, and a corresponding conical surface is formed at the transition between the flange and the column of the rod head 11. The fit between these two conical surfaces creates a conical mating portion 40 between the flange nut 12 and the rod head 11. This conical mating portion 40 further improves the connection strength, rigidity, and anti-loosening capability between the piston rod 4 and the outer sleeve 5. Figure 9 Other aspects of the implementation methods in [the document] may be related to... Figure 6The implementation methods described herein (or modified implementation methods that omit the column and aperture portions) are the same as or similar to those described elsewhere, and will not be described in detail hereafter.

[0060] Figure 10 A modified top structure of the outer sleeve 5 is shown, wherein external threads are machined at the portion of the flange nut 12 where the nut portion 31 protrudes upward from the top plate 10, and a nut 41 and a sealing washer 42 are applied, thereby sealing the gap between the outer periphery of the flange nut 12's nut portion 31 and the center hole of the top plate 10, preventing water or dirt from entering the outer sleeve 5 from above the top plate 10. This improves the cylinder's resistance to environmental contamination. Figure 10 Other aspects of the implementation methods in [the document] may be related to... Figure 6 The implementation methods described herein (or modified implementation methods that omit the column and aperture portions) are the same as or similar to those described elsewhere, and will not be described in detail hereafter.

[0061] Figure 11 The diagram illustrates a feasible structure for a slider 20, which is a two-part assembly structure, with each half capable of snapping onto the piston rod or movable cylinder from its outer periphery. Each half includes a cylindrical portion 50 and a protrusion 51 extending inward from the inner periphery of the cylindrical portion 50. The protrusion 51 is adapted to snap into a groove on the outer periphery of the piston rod or movable cylinder, thereby mounting each half of the slider 20 onto the piston rod or movable cylinder, with the cylindrical portion 50 attached to the outer periphery of the piston rod or movable cylinder.

[0062] Those skilled in the art can make various adaptive modifications to the structure described above according to specific needs.

[0063] While this application has been described herein with reference to specific embodiments, the scope of this application is not limited to the details shown. Various modifications may be made to these details without departing from the basic principles of this application.

Claims

1. A multi-stage hydraulic cylinder, comprising: Fixed cylinder (2); At least one movable cylinder (3) that can extend relative to the fixed cylinder (2); A piston rod (4) that can extend relative to the movable cylinder (3); and The outer sleeve (5) is fixed to the top of the piston rod (4); Among them, a rod head (11) is welded to the top of the piston rod (4), a top plate (10) is welded to the top of the outer sleeve (5), a flange nut (12) is combined with the rod head (11) by thread engagement, and is combined with the top plate (10) by a set of screws (13), and a positioning pin (15) is installed between the flange nut (12) and the rod head (11) to prevent the flange nut (12) and the rod head (11) from rotating relative to each other; The rod head (11) includes a flange (22), a lower end (21) extending downward from the flange (22) and welded to the top of the piston rod (4), a column (23) extending upward from the flange (22), and a threaded section (24) located above the column (23); and The flange nut (12) includes a flange portion (30) and a nut portion (31) extending upward from the flange portion (30). The flange portion (30) is fixed to the lower surface of the top plate (10) by the set of screws (13). The nut portion (31) has a threaded hole portion (35) that engages with the threaded section (24) of the rod head (11).

2. The multi-stage hydraulic cylinder as described in claim 1, wherein, The locating pin (15) passes through one of the through holes (33) in the flange (30) and is inserted into the locating hole (25) in the flange (22).

3. The multi-stage hydraulic cylinder as described in claim 2, wherein, The set of screws (13) engages with a set of screw holes (32) in the flange (30), and the circumferential position of each through hole (33) is set to be offset relative to the circumferential position of each screw hole (32), so that no through hole (33) is located on a radial straight line passing through the center of any screw hole (32).

4. The multi-stage hydraulic cylinder as described in any one of claims 1 to 3, wherein, A conical mating part (40) is provided between the flange nut (12) and the rod head (11).

5. The multi-stage hydraulic cylinder as described in any one of claims 1 to 3, wherein, The nut part (31) passes through the central hole of the top plate (10) and engages with the nut (41) on the outer periphery of the nut part (31) and the corresponding sealing washer (42) to seal the gap between the nut part (31) and the top plate (10).

6. The multi-stage hydraulic cylinder as described in any one of claims 1 to 3, wherein, Each screw (13) is equipped with an anti-loosening washer (14).

7. The multi-stage hydraulic cylinder as described in claim 6, wherein, The anti-loosening washer (14) is a self-locking washer.

8. The multi-stage hydraulic cylinder as described in any one of claims 1 to 3, wherein, The flange nut (12) has undergone nitriding heat treatment.

9. The multi-stage hydraulic cylinder according to any one of claims 1 to 3, wherein, The lower part of the outer wall of each of the piston rod (4) and the movable cylinder (3) is equipped with at least two axially spaced sliders (20).

10. The multi-stage hydraulic cylinder according to any one of claims 1 to 3, wherein, A pair of lower trunnions (18) are mounted on the bottom of the fixed cylinder (2) by means of an integral collar (19), the upper edge of which is welded to the outer wall of the fixed cylinder (2); The lower edge of the collar (19) forms an inwardly turned flange that grips the bottom edge of the fixed cylinder (2); or, the lower edge of the collar (19) is also welded to the outer wall of the fixed cylinder (2).

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