US3466062A - Telescopic tubes - Google Patents

Description

Sept. 9, 1969 H. DEPLANTE TELESCOPIC TUBES Filed July 31. 1967 United States Patent Oihce 3,466,062 Patented Sept. 9, 1969 Int. c1. F161 27704, 27/00, 5/00 U.S. Cl. 285-165 4 Claims ABSTRACT OF THE DISCLOSURE A telescopic tube comprising a first cylinder having with a base in which an aperture is formed, a second cylinder disposed coaxially within the first cylinder in fixed relationship thereto, and a third coaxial cylinder disposed radially between the first two cylinders to slide in a sealed manner through the aperture formed in the base of the first cylinder, and a piston carried by the third cylinder to slide in a sealed manner between said first two cylinders, the third cylinder having an orifice in its cylindrical wall. The Volume occupied by a fluid in such a telescopic tube varies relatively little or not at all during deformation.

The present invention relates to a telescopic tube.

A general way of effecting remote control is to employ a hydraulic circuit. In certain cases, for example in the case of a variable-geometry aircraft of the swing-wing type, part of the circuit is incorporated in a deformable device. Generally speaking, the space containing the hydraulic fluid changes in volume during deformation. The result of this is undesired changes in the pressure of the hydraulic fluid, which reduces the precision of control.

The object of the invention is to provide a telescopic tube in which the volume occupied by the fluid varies relatively little or not at all, during deformation.

The telescopic tube in accordance with the invention comprises a first cylinder equipped with a base in which there is an aperture, a second cylinder parallel to the first, located inside it and fixed in relation thereto, and a third cylinder parallel to the first two and situated between them whilst being able to slide in a sealed manner through the aperture formed in the base of said lirst cylinder, said third cylinder being provided with a piston which is able to slide in a sealed manner between said first two cylinders, the third cylinder in addition containing an orifice in its cylindrical wall.

The following description with reference to the accompanying drawing will indicate by -way of example how the invention maybe carried into practice.

In the drawing:

FIGURE la is an elevational view of one extremity of a telescopic tube in accordance with the invention;

FIGURE lb is an elevational section, on the brokenline Ib-Ib of FIGURE 2b, through the other extremity of the same telescopic tube;

FIGURE 2a is a section, taken on the line IIa--Ila of FIGURE la, of the first extremity of the telescopic tube;

FIGURE 2b is a section, taken on the line IIb-1lb of FIGURE lb, through the other extremity of the telescopic tube.

In the drawing, indicates a first cylinder provided with a base 11 in which there is an aperture, and 12 indicates a second cylinder parallel to the first cylinder 10, located inside it and fixed in relation thereto. The reference 13 indicates a third cylinder, parallel to the first two cylinders 10 and 12 and situated between them. Two seals 14 and 15 are disposed in annular throats produced in the cylindrical internal surface of the base 11 of the first cylinder 10. These seals enable the third cylinder 13 to slide in a sealed manner through the aperture in the base 11 of the first cylinder 10.

The third cylinder 13 is provided, at that extremity situated between the first cylinder 10 and the second cylinder 12, which an annular piston 43 capable of sliding in a sealed manner between said two cylinders. The piston 43 possesses two annular seals 44 and 45 disposed in undercuts produced in the cylindrical external surface of the piston, and a seal 46 situated in an undercut produced in the cylindrical internal surface of the piston. These three seals 46, 44 and 45 ensure that the piston 43 cooperates in sealing relationship with the first cylinder 10 and with the second cylinder 12.

The cylindrical wall of the third cylinder 13 is pierced by orifices 16 situated in a transverse ring and allowing communication between an annular space 47 formed between the first cylinder 10 and the third cylinder 13 and an annular space 48 formed between the second cylinder 12 and the third cylinder 13. A collar 17 carried by the third cylinder 13 is situated in the neighbourhood of the orifices 16. The periphery of this collar is crenellated and fluid therefore fiows past it when the third cylinder 13 and its piston 43 are displaced. It acts as a mechanical stop, in conjunction `with the base 11 of the first cylinder 10, to limit the maximum extension of the telescopic tube formed by the above-described arrangement of cylinders.

If, for example, it is assumed that the third cylinder 13 and its piston 43 are being displaced towards the right in relation to the rigid assembly constituted by the first cylinder 10 and the second cylinder 12, and if the area of the internal transverse cross section of the third cylinder 13 is designated S, it will be apparent that the volume occupied by the fluid at the right of the second cylinder 12 increases by a volume equal to the product of the longitudinal displacement of the third cylinder 13 and the area S. However, at the same time, the volume occupied by the fluid in the annular space 47 formed between the first cylinder 10 and the third cylinder 13, and in the annular space 48 formed between the second cylinder 12 and the third cylinder 13, diminishes by a volume equal to the product of the displacement of the cylinder 13 and the sum of the areas of the transverse cross sections S1 and S2 of said annular spaces 47 and 48. If S=S1+S2, the total volume occupied by the fluid is unchanged. If to the two members of this equation there is added the area of the transverse cross section of the wall of the third cylinder 13, the new equivalent resulting equation may be expressed as follows: the cross sections of the third cylinder 13, including its Wall, and of the annular space defined by the first cylinder 10 and the second cylinder 12 have substantially equal areas.

Generally speaking, there will not be only a longitudinal displacement of the third cylinder 13 in relation to the first cylinder 10 and the second cylinder 12. If, for example, the telescopic tube is linking the fuselage to the swing-wing of a variable-geometry aircraft, it is necessary generally speaking, at one end of the telescopic tube, for the rigid part constituted by the first and second cylinders (or for that matter at the other end for the rigid part constituted by the third cylinder), to be connected to a union which is able to swivel in relation to the ltube about a geometric axis which can adopt any desired spatial orientation. This movement is provided by creating a universal joint between one of these two rigid parts and the union. A joint of this sort is illustrated in the drawing for each of -the said two rigid parts.

At the right-hand side of FIGURE 2b, the third cylinder 13 is continued in the form of a terminal portion 49 of reduced section, containing a bore 51. A first union 34, containing a bore 53 communicating with the bore 51, can swivel about the terminal portion 49 and a second union 35, containing a bore 36 communicating with the bore 53, can swivel about the first union 34. Nuts 41, 42 and 5S, washers 50, 52 and 54 and seals 37, 38, 39, 40, 56 and S7 serve to fix the components together and provide sealing.

At the left-hand side of the FIGURE 2a, the second tube 12 terminates in an enlarged cylindrical portion 25 carrying a flange 24 which bears against a shoulder 20 on the first tube 10. An elbow union 18 containing a bore 58 is provided, having two branches 28 and 29 at right-angles to one another, the first of which enters the enlarged portion 2S and possesses a collar 19 which bears against the ange 24 so that the union 18 can swivel about the longitudinal axis of the telescopic tube. Another union 33, containing a bore 23 communicating with the bore 58, can swivel about the arm 29 of the union 18. Nuts 21, 30 and 22 and seals 26, 31 and 32 lock and seal the assembly.

A thrust washer is located between the nut 21 and the collar 19. This washer is of the split type, the split plane being in the plane of section of the drawing (FIGURE 2a). Undercuts 60 and 63 are formed in the periphery of the enlarged cylindrical portion 25 and in the periphery of -the collar 19. The volume 62 formed between the enlarged portion 25 and the piston 43 communicates with I claim:

1. A telescopic tube comprising a first cylinder having an apertured base, a second cylinder disposed inside in the first cylinder in fixed coaxial relationship thereto, a third cylinder coaxial with said rst two cylinders and disposed radially between them to slide in the axial direction through the aperture formed in the base of the first cylinder, said third cylinder and said aperture being in sealing relationship, and an annular piston carried by the third cylinder to slide between said first two cylinders, said piston and the walls of said first two cylinders being in sealing relationship, and the Ithird cylinder in addition having an orifice in its cylindrical wall putting into cornmunication an annular space formed between the first and third cylinders and an annular space formed between the second and third cylinders.

2. A telescopic tube as claimed in claim 1, in which the external cross sectional area of the third cylinder is equal to the cross-sectional area of the annular space between the first and second cylinders.

3. A telescopic tube as claimed in claim 1 including a universal joint to which the first and second cylinders are connected at their ends remote from the base of the first cylinder.

4. A telescopic tube as claimed in claim 3, including a universal joint to which the third cylinder is connected at its end adjacent the base of the first cylinder.

References Cited UNITED STATES PATENTS 2,455,334 11/1948 Hill et al. 137-580 M. CARY NELSON, Primary Examiner WILLIAM R. CLINE, Assistant Examiner U.S. C1. X.R.

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