CLEANING ASSEMBLY AND METHOD FOR A SHAFT

Abstract

A cylinder assembly comprising at least one tubular section with an open end and an opposite end closed by a cylinder head, the tubular section comprising a tubular member, the cylinder assembly further comprising a shaver secured to an inner wall of the cylinder head; and the shaver having an edge having a round profile, with a curvature radius comprised in a range between 0.0002 and 0.002, an inner diameter equal to an outer diameter of the tubular member and a surface hardness at least equal to a hardness of the surface of the tubular member.

Claims

1. A cylinder comprising at least one tubular section with an open end and an opposite end closed by a cylinder head, the tubular section comprising an outer tubular member, an inner tubular member telescopically displaceable in said outer tubular member, and a shaver secured to an inner wall of the cylinder head; wherein said cylinder further comprises at least one of: i) a cutting edge of the shaver having a round profile; ii) an inner diameter of the shaver equal to an outer diameter of said inner tubular member; and iii) a wear ring positioned between said shaver and a sealing ring of the cylinder head.

2. The cylinder of claim 1, comprising a wiper mounted between said outer tubular member and said inner tubular member, said sealing ring of the cylinder head being positioned downstream of said wiper.

3. The cylinder of claim 1, further comprising wear rings positioned downstream of the sealing ring of the cylinder head.

4. The cylinder of claim 1, wherein the cutting edge of the shaver has a round profile.

5. The cylinder of claim 1, wherein the inner diameter of the shaver is equal to the outer diameter of said inner tubular member.

6. The cylinder of claim 1, comprising a wear ring positioned between said shaver and the sealing ring of the cylinder head.

7. The cylinder of claim 1, wherein the cutting edge of the shaver has a round profile and the inner diameter of the shaver is equal to the outer diameter of said inner tubular member.

8. The cylinder of claim 1, comprising a wear ring positioned between said shaver and the sealing ring of the cylinder head and the cutting edge of the shaver having a round profile.

9. The cylinder of claim 1, comprising a wear ring positioned between said shaver and the sealing ring of the cylinder head and the inner diameter of the shaver being equal to the outer diameter of said inner tubular member.

10. The cylinder of claim 1, comprising a wear ring positioned between said shaver and the sealing ring of the cylinder head, the inner diameter of the shaver being equal to the outer diameter of said inner tubular member and the cutting edge of the shaver having a round profile.

11. The cylinder of claim 1, wherein the cutting edge of the shaver has a curvature radius comprised in a range between 0.0002 and 0.002.

12. The cylinder of claim 1, wherein said shaver has a surface hardness at least equal to a hardness of the surface of the inner tubular member.

13. A cylinder assembly comprising at least one tubular section with an open end and an opposite end closed by a cylinder head, the tubular section comprising a tubular member, the cylinder assembly further comprising a shaver secured to an inner wall of the cylinder head; wherein said shaver has an edge having a round profile, with a curvature radius comprised in a range between 0.0002 and 0.002, an inner diameter equal to an outer diameter of the tubular member and a surface hardness at least equal to a hardness of the surface of the tubular member.

14. The cylinder assembly according to claim 13, wherein the curvature radius of the edge of the shaver is comprised in a range between 0.001 and 0.002.

15. The cylinder assembly according to claim 13, further comprising a wear ring positioned between the shaver and a sealing ring of the cylinder head, and a wiper mounted between an outer tubular member and the tubular member, upstream of the sealing ring of the cylinder head.

16. The cylinder assembly according to claim 13, further comprising a wear ring positioned between the shaver and a sealing ring of the cylinder head, and wear rings positioning downstream of the sealing ring of the cylinder head.

17. The cylinder assembly according to claim 13, further comprising a wear ring between the shaver and a sealing ring of the cylinder head.

18. A cylinder assembly comprising at least one tubular section with an open end and an opposite end closed by a cylinder head, the tubular section comprising a tubular member having a first hardness, the cylinder assembly further comprising a shaver, wherein said shaver comprises an edge having a curvature radius comprised in a range between 0.0002 and 0.002, an inner diameter equal to an outer diameter of the tubular member, and a surface hardness at least equal to the first hardness.

19. The cylinder assembly of claim 18, further comprising a wear ring between the shaver and a sealing ring of the cylinder head.

20. The cylinder assembly of claim 18, wherein the curvature radius of the edge of the shaver is comprised in a range between 0.001 and 0.002.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] In the appended drawings:

[0012] FIG. 1 is a partial longitudinal cross-sectional view of a tubular section of a telescopic cylinder according to an embodiment of an aspect of the present invention;

[0013] FIG. 2 is a side view of FIG. 1;

[0014] FIG. 3 is cross section of FIG. 2 along A-A;

[0015] FIG. 4 is a detail of a cylinder head according to an embodiment of an aspect of the present invention;

[0016] FIG. 5A show a detail of a cutting tip of a shaver of a cylinder head according to an embodiment of an aspect of the present invention;

[0017] FIG. 5B show a detail of a cutting tip of a shaver of a cylinder head according to an embodiment of an aspect of the present invention;

[0018] FIG. 5C show a detail of a cutting tip of a shaver of a cylinder head according to an embodiment of an aspect of the present invention;

[0019] FIG. 5D shows a shaver of a cylinder head according to an embodiment of an aspect of the present invention;

[0020] FIG. 5E is a section of FIG. 5D along A-A;

[0021] FIG. 6 show results of a comparative test of surface roughness of an inner tubular member of cylinders a) of the prior art; b) with a shaver having an inner diameter increased over of the prior art; c) with a shaver having an inner diameter increased over of the prior art, and a wear ring positioned upstream of the sealing ring according to an embodiment of an aspect of the present invention; d) in the case of a wear ring positioned between the shaver and the sealing ring and with a shaver having an inner diameter increased over of the prior art as well as a round cutting edge, according to an embodiment of an aspect of the present invention; and e) in the case of a wear ring positioned between the shaver and the sealing ring and with a shaver having an inner diameter increased over of the prior art as well as a round cutting edge and with an inner tubular member provided with a polymeric surface impregnation, according to an embodiment of an aspect of the present invention;

[0022] FIG. 7A shows an inner tubular section with a layer of paint on the outer surface thereof as a reference;

[0023] FIG. 7B shows the inner tubular section of FIG. 7A after 10 cycles with a cylinder of the prior art;

[0024] FIG. 7C shows the inner tubular section of FIG. 7A after 1 cycle with a cylinder provided with a wear ring positioned between the shaver and the sealing ring and with the shaver having an inner diameter increased over of the prior art as well as a round cutting edge according to an embodiment of an aspect of the present invention; and

[0025] FIG. 7D shows the inner tubular section of FIG. 7A after 10 cycles with a cylinder provided with a wear ring positioned between the shaver and the sealing ring and with the shaver having an inner diameter increased over of the prior art as well as a round cutting edge according to an embodiment of an aspect of the present invention.

DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0026] For clarity purposes, the invention will be described in relation to a structure made of a series of series of tubular sections telescopically arranged in a tubular housing, each of the tubular sections having one end provided with a cylinder head, and comprising an inner tubular member telescopically displaceable in an outer tubular member respectively, such as a telescopic cylinder for example, intended for use in contaminated environments.

[0027] A telescopic cylinder may comprise a series of tubular sections 12, each tubular section comprising an inner tubular member 18 telescopically displaceable in an outer tubular member 24, with a wiper 50 mounted between the outer tubular member 24 and the inner tubular member 18. As illustrated for example in FIGS. 1-3, the tubular section 12 has one end provided with a cylinder head 28. The head 28 comprises a sealing ring 70 typically in a plastic material, urethane, or Teflon for example to prevent pressurized oil from leaking past the interface between the rod inner tubular member 18 and the head 20. As best seen in FIG. 3, the cylinder head 28 has an outer wall having an enlarged annular portion 30.

[0028] A shaver 32 is lodged in a corresponding circumferential recess in an inner wall of the cylinder head 28, with an O-ring 38. The shaver 32 is secured by a flange 42 against a lateral surface of the enlarged annular portion 30 of the cylinder head 28, for example by screws 44, so that the shaver 32 slides on an outer surface of the inner tubular member 18, thereby scraping contamination such as organic material or mineral material away from the outer surface of the inner tubular member 18. Wear rings 53 are positioned downstream of the sealing ring 70, away from the open end of the tubular arrangement.

[0029] The cutting edge 60 of the shaver 32 is selected to have a round profile, i.e. a tip with a curvature radius, for example between 0.0002 and 0.002 (see FIG. 5C), which is found to reduce wearing out of the surface of the inner tubular member 18.

[0030] As shown in FIGS. 5D and 5E, the shaver 32 has an inner diameter 33 and an outer diameter 35. The inner diameter 33 of the shaver 32 is selected so that its inner diameter is substantially equal (+0.001/0.001) to the outer diameter of the inner tubular member 18, as opposed to the prior art which taught using a shaver having an inner diameter smaller than the inner tubular member 18.

[0031] It is found that the inner diameter 33 of the shaver 32 close to the outer diameter of the inner tubular member 18 allows uniformity of the radial pressure submitted to the perimeter of the inner tubular member 18 by the shaver 32.

[0032] A wear ring 52 is positioned upstream of the sealing ring 70, i.e. between the shaver 32 and the sealing ring 70. The wear ring 52 takes over part of lateral loads applied on the cylinder, i.e. forces submitted generally perpendicularly to the longitudinal axis of the telescopic cylinder, stabilizes the cylinder head 28 and prevents excess pressure from the shaver 32 on the surface of the tubular member 18.

[0033] Each one of these features, i.e. the round shape of the edge of the shaver, the inner diameter 33 of the shaver 32 selected to match the outer diameter of the inner tubular member 18, and the wear ring 52 positioned upstream of the sealing ring 70, can be provided independently or in combination 2 by 2 or the three of them together. Each one of them is found to allow reducing the wear of the surface of the inner tubular member 18 over time, i.e. contribute to maintain the surface roughness RA of the inner tubular member over time.

[0034] For example, the round profile of the cutting edge 60 of the shaver 32 can be provided independently to improve the uniformity of the scrapping action and the uniformity of the radial pressure submitted to the surface of the inner tubular member 18 by the shaver 32.

[0035] FIG. 6 show results of comparative tests of surface roughness of inner tubular members of cylinders a) of the prior art; b) with a shaver having an inner diameter increased over of the prior art; c) with a shaver having an inner diameter increased over of the prior art, and the wear ring 52 positioned upstream of the sealing ring 70 between the shaver 32 and the sealing ring 70; d) in the case of a wear ring positioned between the shaver and the sealing ring and with a shaver having an inner diameter increased over of the prior art as well as a round cutting edge, and e) in the case of a wear ring positioned between the shaver and the sealing ring and with a shaver having an inner diameter increased over of the prior art as well as a round cutting edge, and with an inner tubular member provided with a polymeric surface impregnation, provided as anticorrosion layer.

[0036] The combination of i) the wear ring 52 positioned upstream of the sealing ring 70, i.e. between the shaver 32 and the sealing ring 70, and of ii) the inner diameter of the shaver 32 selected to be as close as possible to the outer diameter of the inner tubular member 18 (see graph c of FIG. 6) yields an optimized and maintained surface roughness, i.e. of about 4 Ra, of the inner tubular member 18 over time.

[0037] The combination of i) the wear ring 52 positioned upstream of the sealing ring 70, i.e. between the shaver 32 and the sealing ring 70, of ii) the inner diameter of the shaver 32 as close as possible top the outer diameter of the inner tubular member 18 and of iii) the round cutting edge of the shaver 32 (see graph d of FIG. 6) yields an optimized and maintained surface roughness, i.e. above 6 Ra for example, of the inner tubular member 18 over time. A polymeric surface layer, used for resistance to corrosion, does not impact the performance of the combination (see graph e of FIG. 6).

[0038] As illustrated in FIG. 7, such a shaver 32 proves to be very efficient in scrapping away cooked organic and mineral contaminants from the outer surface of tubular members, while reducing wearing out of the surface of the tubular members.

[0039] FIG. 7 show A) an inner tubular section with a layer of paint on the outer surface thereof as a reference; B) the inner tubular section after 10 cycles with a cylinder of the prior art; C) the inner tubular section after 1 cycle with a cylinder provided with a wear ring positioned between the shaver and the sealing ring and with the shaver having an inner diameter increased over of the prior art as well as a round cutting edge according to an embodiment of an aspect of the present invention; and D) the inner tubular section after 10 cycles with a cylinder provided with a wear ring positioned between the shaver and the sealing ring and with the shaver having an inner diameter increased over of the prior art as well as a round cutting edge according to an embodiment of an aspect of the present invention. The efficiency of paint removal is improved using a cylinder provided with a wear ring positioned between the shaver and the sealing ring and with the shaver having an increased inner diameter (see FIGS. 7C and 7D).

[0040] The shaver 32 is made in a material characterized by a hardness at least equal to the hardness of the inner tubular member 18. A material suitable for making cutting tools like a tool steel of a steel M2 type may be selected for the shaver 32. For example, for an inner tubular 18 hardness of 800 HV, a material having a hardness of 950 HV may be selected for the shaver 32.

[0041] Alternatively, for the shaver 32, a coated steel with a hard coating, i.e. a coating having a hardness at least equal to the hardness of the inner tubular member 18, for example of at least 800 HV hardness, and auto lubricating and anti-adhesive properties, such as D.L.C (Diamond Like Carbon), of a thickness in a range between 4 and 35 micrometers, may be used. DLC is known to have a small coefficient of friction and an excellent surface smoothness; the hardness of DLC is comprised between 3,500 and 4,000 HV, and its abrasion resistance, as measured by the rate of decrease of the surface roughness Ra for example, is excellent. DLC coatings are known for combining wear resistance, linked to hardness, and self-lubricating capacity. Other hard coatings, i.e. coatings of a hardness at least as high as the hardness of the inner tubular member 18 may be contemplated, such as We-MoCr of hardness 1700 HV or CrC of hardness 1500 HV for example.

[0042] The pressure with which the shaver 32 is in contact with the outer surface of the inner tubular member is adjusted by controlling the compression of the O-ring 38, such as a nitrile O-ring joint, so that the pressure exerted by the blade on the outer surface of the inner tubular member 18 is at least 10 lb/inch.sup.2.

[0043] The outer surface of the tubular member 18 to be cleaned may previously be submitted to a hardening treatment such as a nitriding treatment, so as to obtain a higher superficial hardness, i.e. a hardness in a range between 50 and 65 RC, i.e. between about 520 and 850 HV, over a thickness in a range between 10 and 30 micrometers and an increased surface lubrication capacity due to reduced friction, in such a way that a surface finish of the tubular member 18 may be further protected against an aggressive action of the shaver 32.

[0044] The present combination provides uniformity of the radial pressure submitted to the perimeter of the inner tubular member 18 by the shaver 32 and thereby reduces wearing off the surface roughness of the inner tubular member 18 while efficiently scrapping away contaminants from the outer surface of the tubular member 18.

[0045] The scope of the claims should not be limited by the preferred embodiments set forth in the examples, but should be given the broadest interpretation consistent with the description as a whole.