GB2207071A

GB2207071A - Hydraulic expansion device

Info

Publication number: GB2207071A
Application number: GB08814490A
Authority: GB
Inventors: Herbert Frielingsdorf; Karl Dr Weiss; Heribert Grewe; Engelbert Schwarz
Original assignee: Emitec Gesellschaft fuer Emissionstechnologie mbH
Current assignee: Vitesco Technologies Lohmar Verwaltungs GmbH
Priority date: 1987-06-20
Filing date: 1988-06-17
Publication date: 1989-01-25
Anticipated expiration: 2008-06-17
Also published as: GB8814490D0; IT8805179A0; FR2616698A1; FR2616698B1; GB2207071B; DE3720486C1; ES2010279A6

Description

e. 1 1 2 2 0 7 CJ 7 11 1 HYDRAULIC EXPANSION DEVICE This invention relates

to a hydraulic expansion device insertable into a hollow shaft for expanding the wall of the shaft radially outwardly at a plurality of axially spaced apart locations. Particularly, but not exclusively, the Invention relates to such a hydraulic expansion device for use in the production of a camshaft wherein camshaft elements such as cams, gears, bearings etc. are individually secured to the shaft by radially outward expansion of the shaft wall into securing engagement within apertures in the camshaft elements.

A hydraulic expansion device is known for example from DE-A-3530600 wherein the device includes a plurality of axially spaced apart O-rings, sealingly engageable with the interior shaft wall, and a plurality of radially extending bores communicating between a common fluid supply conduit and annular spaces defined between pairs of adjacent sealing rings, the adjacent shaft wall and the radially outer surface of the device. Pressurised hydraulic fluid supplied to the supply conduit thus enables simultaneous hydraulic pressure to be applied to said annular spaces to radially outwardly expand the shaft wall at a plurality of axially spaced apart locations.

Problems can occur in use of the device described above if the hollow shaft Is not linearly true in that, since the device is an elongate rigid member, the sealing rings may not seal properly to the interior wall of the shaft. It is an object of the present invention to provide a new or improved hydraulic expansion device 2 which will overcome problems occurring in its use in hollow shafts which have Irregularities in their linearity.

In accordance with the invention there is provided a hydraulic expansion device insertable into a hollow shaft for expanding the wall of said shaft radially outwardly at a plurality of axially spaced apart locations comprising a plurality of axially spaced apart hydraulic expansion elements, adjacent said expansion elements being interconnected by a hydraulic fluid supply conduit; each said element including sealing means for sealing said element to the Interior wall of the shaft and a radially extending fluid supply bore communicating between said supply conduit and the radially outer surface of said element for applying hydraulic pressure to the adjacent part of the shaft wall; at least one pair of adjacent expansion elements being angularly displaceable relative to one another for accommodating irregularities in the linearity of the hollow shaft.

Preferably the sealing means comprises axially spaced apart sealing means on each said expansion element with the radially extending fluid supply bore communicating with the radially outer surface of a said element at a position intermediate the sealing means.

The supply conduit may comprise a plurality of conduit elements, at least one of which is flexible, connected between said expansion elements; each said expansion element including an axially extending bore communicating with the conduit element to which the said expansion element Is connected, said radially extending supply bore in each said expansion element communicating with said axially extending supply bore therein. A said i i 1 1 J i 1 i 1 1 3 conduit element may be connected to a said expansion element by means of a screw threaded bush engaged about an end of the conduit element and screwed into an adjacent end of the expansion element and, conveniently, a sealing sleeve is screw threaded onto a said end of the conduit element and is located between said end and the interior of said bush, the screw thread of the sleeve being of opposite hand to that of the screw thread of the bush. Each end of a said conduit element conveniently comprises a conical sealing surface engaged with a cooperating seating at the end of said axially extending supply bore in a said expansion element.

Alternatively, the supply conduit may comprise a flexible continuous conduit on which said expansion elements are mounted, said radially extending supply bore in each said expansion element communicating with said supply conduit within said element. In this construction, each expansion element is conveniently connected to the supply conduit by means of a screw threaded bush engaged about the conduit and screwed into an end of the expansion element, a compressible clamping sleeve being located between the interior of said bush and the conduit. Alternatively, each said expansion element may be welded or soldered to the supply conduit.

The expansion elements may each be provided with an open-ended axially extending pressure relief bore and, additionally, a radially extending pressure relief bore.

Preferably at least part of the supply conduit extending between each pair of adjacent expansion elements is flexi61e.

4 Also in accordance with the invention there is provided a hollow shaft having a plurality of axially spaced apart radially outwardly expanded wall portions produced by a hydraulic expansion device as described in the preceding paragraphs. Also in accordance with the Invention there is provided a camshaft comprising such a hollow shaft with a cam, gear, bearing or like camshaft element secured thereon at each of said radially outwardly expanded wall portions.

Other features of the invention will become apparent from the following description given herein solely by way of example with reference to the accompanying drawings wherein

Figure 1 is a side part elevation, part cross sectional view of a hydraulic expansion device constructed in accordance with the invention; and Figure 2 is a similar view of an alternative form of hydraulic expansion device in accordance with the invention.

Referring to Figure 1 of the drawings there is Illustrated a hydraulic expansion device in accordance with the invention insertable, in use, into a hollow shaft for expanding the wall of the shaft radially outwardly at a plurality of axially spaced apart locations. The device comprises a plurality of axially spaced apart hydraulic expansion elements 10, 12 interconnected by a plurality of conduit elements 14, 16, 18, 20 at least one of which is, at least in part, flexible for accommodating irregularities in the linearity of a hollow shaft into which the device is to be inserted.

i j i As shown in Figure 1, the left hand conduit element 14 is, at its outer end, sealingly secured to a source 22 of pressurisable hydraulic fluid by means of a suitable screw threaded clamping bush assembly 24. The inner end of each conduit element (see particularly element 16) is tapered to comprise a conical sealing surface 26 engageable with a cooperating seating at an end of an axially extending fluid supply bore 28 in the adjacent said expansion element 10. A similar conduit element 18 interconnects said expansion element 10 to the next adjacent expansion element and the outer end of the axial bore in the end one 12 of the expansion elements is sealed with a closure cap 30. It will be appreciated that, in Figure 1, only one intermediate expansion element 10 and an end expansion element 12 are shown.

Each said expansion element comprises a rigid body of cylindrical form having an outer diameter slightly less than the internal diameter of the hollow shaft into which the device is to be inserted. Each element is counter-bored at each end to receive a screw threaded bush 32 engaged about an adjacent end of a conduit element and screwed into the counterbore. The bush 32 is itself counter-bored at its inner end to receive a sealing sleeve 34 also screw threaded onto the conduit element with the screw thread of the sleeve being of opposite hand to that of the screw thread of the bush. It will be appreciated that such a bush and sleeve sealing connection 32-34 is established between a respective end of each conduit element and a respective expansion element I.e. as shown in cross-section at the left hand end of element 10.

A pair of circumferential recesses 36-38 are provided in each expansion element within each of which 11 T 6 is located a sealing ring (not shown). The outer diameter of each sealing ring is slightly greater than the internal diameter of the shaft into which the device is to be inserted whereby each expansion element 10, 12 etc. may be sealed to the interior wall of the shaft to define an annular space between each pair of sealing rings 36-38, the adjacent interior wall of the shaft and the radially outer surface of the expansion element. A radially extending fluid supply bore 40 communicates between the axial bore 28 in each said expansion element and the aforesaid annular space between the sealing rings whereby pressurised hydraulic fluid supplied from the fluid source 22 may be applied to each of said annular spaces to expand the adjacent part of the shaft wall radially outwardly.

As stated above, at least one of the conduit elements 14, 16, 18, 20 is, at least in part, flexible for accommodating irregularities in the linearity of the hollow shaft whilst still enabling the sealing rings 36-38 to effect good sealing engagement with the interior wall of the shaft. Preferably each of the Interconnecting conduit elements is, at least in part, f lexible.

Each of the expansion elements is conveniently, as shown in Figure 1, provided with an open ended axially extending pressure relief bore 42 opening into the spaces between adjacent expansion elements. Also, as illustrated, each expansion element may be provided with a radially extending pressure relief bore 44 communicating between the radially outer surface of each said expansion element and a location adjacent the position of sealing engagement between each end of a conduit element and an expansion element.

i i 1 i i i 1 i i 1 1 1 1 i i 1 i 1 f i 1 i t 1 i i i j 7 1 An alternative construction of hydraulic expansion device constructed in accordance with the invention is shown in Figure 2 of the drawings wherein like reference numerals refer to like parts hereinbefore described. In this construction, there is again provided a plurality of individual hydraulic expansion elements (two such elements 10 and 12 being shown) but, in this case, each of such elements is mounted on a common supply conduit 50 at axially spaced apart positions therealong. At least part of at least one of the interconnecting portions 52, 54, 56, 58 of the common supply conduit between adjacent expansion elements is flexible and, preferably, at least part of all of such interconnecting portions is flexible for overcoming the sealing problems which may occur when the device is used in a hollow shaft having irregularities in its linearity.

In the construction shown in Figure 2, each of the expansion elements again comprises a rigid cylindrical body having a pair of axially spaced apart circumferential recesses 36-38 receiving sealing rings therein. Each expansion element is provided with a central through bore of a diameter only slightly greater than the external diameter of the common supply conduit. A radially extending fluid supply bore 40 in each expansion element communicates between the radially outer surface of said element intermediate the sealing rings 36-38 and a port 60 provided in the common supply conduit in communication with said radially extending bore 40 at Its radially Inner end. Each end of each expansion element is counter-bored to receive a screw threaded bush 32 engaged about the supply conduit and screwed into the counter-bore with wedging engagement about a compressible clamping sleeve 62 located between the interior of a 1 1 i i i i 8 counter-bore In the bush and the conduit I.e. as shown in cross-section at the left hand end of element 10.

Thus, as in the Figure 1 construction, pressurised hydraulic fluid supplied to the common supply conduit from the fluid source 22 enables the application of pressurised fluid to each of the annular spaces defined between each pair of sealing rings 36-38, the adjacent interior shaft wall and the radially outer surface of the expansion element.

Thus a hydraulic expansion device constructed in accordance with the invention and as exemplified by either of the two embodiments described above provides a plurality of rigid individual hydraulic expansion elements each sealingly engageable with the interior wall of a hollow shaft even if such shaft is not linearly true since any irregularity in the linearity can be accommodated due to the flexibility of the interconnecting parts of the fluid supply conduit whether or not they are individual conduit elements 14, 16, 18, 20 as illustrated in Figure 1 or interconnecting portions 52, 54, 56, 58 of a common supply conduit 50 as illustrated in Figure 2. It will be appreciated that each of the expansion elements may itself comprise a plurality of sections which are for example screwed together to form each said individual expansion element.

The hydraulic expansion device thus enables simultaneous radially outward expansion of a hollow shaft at a plurality of axially spaced apart locations. The device is particularly suitable for use in the fabrication of a camshaft wherein a plurality of individual camshaft elements such as cams, gears, bearings etc. are secured about the shaft at a plurality i 1 1 1 1 9 of axially spaced apart locations; the radially outward expansion of the shaft wall effecting the securing of each said camshaft element to the shaft.

1 1 11

Claims

1. A hydraulic expansion do-vice Insertable into a hollow shaft for expanding the wall of said shaft radially outwardly at a plurality of axially spaced apart locations comprising a plurality of axially spaced apart hydraulic expansion elements, adjacent said expansion elements being interconnected by a hydraulic fluid supply conduit; each said element including scaling means for sealing said element to the interior wall of the shaft and a radially extending fluid supply bore communicating between said supply conduit and the radially outer surface of said element for applying hydraulic pressure to the adjacent part of the shaft wall; at least one pair of adjacent expansion elements being angularly displaceable relative to one another for accommodating irregularities in the linearity of the hollow shaft.

2. A hydraulic expansion device as claimed In Claim 1 wherein the sealing means comprises axially spaced apart sealing means on each said expansion element and the radially extending fluid supply bore communicates with the radially outer surface of a said element at a positin intermediate the sealing means.

3. A hydraulic expansion device as claimed in either one of Claims 1 or 2 wherein the supply conduit comprises a plurality of conduit elements, at least one of which is flexible.. connected between said expansion elements; each said expansion element including an axially extending bore communicating with the conduit element to which the said expansion element is connected, said radially extending supply bore in each said expansion element communicating with said axially extending supply bore therein.

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4 1 4 4. A hydraulic expansion device as claimed in either one of Claims 1 or 2 wherein the supply conduit comprises a flexible continuous conduit on which said expansion elements are mounted, said radially extending supply bore in each said expansion element communicating with said supply conduit within said element.

5. A hydraulic expansion device as claimed in Claim 3 wherein a said conduit element is connected to a said expansion element by means of a screw threaded bush engaged about an end of the conduit element and screwed into an adjacent end of the expansion element.

6. A hydraulic expansion device as claimed in Claim 5 wherein a sealing sleeve is screw threaded onto a said end of the conduit element and is located between said end and the interior of said bush, the screw thread of said sleeve being of opposite hand to that of the screw thread of the bush.

7. A hydraulic expansion device as claimed in any one of Claims 3, 5 or 6 wherein each end of a said conduit element comprises a conical sealing surface engaged with a cooperating seating at the end of said axially extending supply bore In a said expansion element.

8. A hydraulic expansion device as claimed in Claim 4 wherein each expansion element is.connected to the supply conduit by means of a screw threaded bush engaged about the conduit and screwed into an end of the expansion element, a compressible clamping sleeve being located between the interior of said bush and the conduit.

9. A hydraulic expansion device as claimed in Claim 4 1 i i 12 wherein each said expansion element is welded or soldered to the supply conduit.

10. A hydraulic expansion device as claimed in any one of the preceding claims wherein the expansion elements are each provided with an open ended axially extending pressure relief bore.

11. A hydraulic expansion device as claimed in any one of the preceding claims wherein the expansion elements are each provided with a radially extending pressure relief bore.

12. A hydraulic expansion device as claimed in any one of the preceding claims wherein at least part of the supply conduit extending between each pair of adjacent expansion elements is flexible.

13. A hydraulic expansion device constructed and arranged substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

14. A hydraulic expansion device constructed and arranged substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

15. A hollow shaft having a plurality of axially spaced apart radially outwardly expanded wall portions produced by a hydraulic expansion device as claimed in any one of the preceding claims.

16. A camshaft comprising a hollow shaft as claimed in Claim 15 with a cam, gear, bearing or like camshaft element secured thereon at each of said radially outwardly expanded wall portions.

Published 1988 at The Patent Office, State House, 616-71 High Holborn, iondon WC1R 4TP. Further copies may be obtained from The Patent 0Mce. Sales Branch, St Mary Cray. Orpingtorl, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent. Con 1'87.

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