GB2206515A

GB2206515A - Hydraulic expansion device

Info

Publication number: GB2206515A
Application number: GB08814489A
Authority: GB
Inventors: Herbert Frielingsdorf; Karl Dr Weiss; Heribert Grewe; Engelbert Schwarz; Helmut Riemscheid; Rudolf J Schulz
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: 1989-01-11
Anticipated expiration: 2008-06-17
Also published as: GB8814489D0; FR2616699A1; GB2206515B; FR2616699B1; ES2010280A6; DE3720487C1; IT8805180A0

Description

2A/_ n065 10 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 simultaneou-s hydraulic pressure to be applied to said annular spaces to radially outwardly expand the shaft wall at a plurality of axially spaced apart locations.

A problem in the construction of such a device as described above is that it comprises a unitary member with a central fluid supply conduit formed as a bore and it can be difficult to form such a bore in a relatively long such member. Also, a specific device is required to be constructed according to the required number and 2 spacings of the radially outwardly expanded locations in the shaft. It is an object of the present invention to provide a new or improved hydraulic expansion device which will overcome the problems referred to above.

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 individual hydraulic expansion elements and a hydraulic fluid supply conduit; means for sealing said elements to the interior wall of the shaft and a radially extending fluid supply bore in each said expansion element communicating between said supply conduit and the radially outer surface of said element for applying hydraulic pressure to the adjacent wall of the hollow shaft.

Each said expansion element may include a pair of axially spaced apart sealing means; said radially extending bore communicating between an axial bore in said element and the radially outer surface thereof intermediate said sealing means, said axial bore in each said expansion element forming a part of said fluid supply conduit.

Alternatively, in an adjacent pair of said expansion elements, one of said elements may include sealing means axially spaced apart from the sealing means of a said adjacent said expansion element; said radially extending bore in one of said expansion elements communicating between an axial bore in said element and the radially outer surface thereof intermediate said sealing means, said axial bore in said expansion element forming a part of said fluid supply conduit.

3 Alternatively again, in an adjacent pair of said expansion elements, an annular peripheral recess may be defined between said elements within which is located a radially outwardly expandable sleeve; said radially extending bore in one of said expansion elements communicating between an axial bore in said element and said sleeve, said axial bore in said expansion element forming a part of said fluid supply conduit.

In an adjacent pair of expansion elements, an end of one said element may conveniently comprise a spigot received within a complimentary recess at the end of the adjacent element and a pair of such adjacent elements may be connected together by screw means, bayonet means, welding or other means of securement.

Preferably, each of said expansion elements is a rigid member and all of said expansion elements are connected together adjacent one another to form a rigid unit throughout the length of the device. Alternatively, each said expansion element may be axially spaced from an adjacent said element by an interconnecting portion of said fluid supply conduit.

Each of said expansion elements may be provided with an open-ended axially extending pressure relief bore and a radially extending pressure relief bore.

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 above. The invention also provides a camshaft comprising such a hollow shaft with a cam, gear, bearing or like 4 Ir 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 cross sectional view of a hydraulic expansion device constructed in accordance with the invention; Figure 2 is a side cross sectional view of an alternative embodiment of hydraulic expansion device; Figure 3 is a side cross sectional view of a still further embodiment of 1?ydraulic expansion device; and Figure 4 is a side part elevation, part cross sectional view of a yet further embodiment of hydraulic expansion device.

Referring to Figure 1 of the drawings there is illustrated a hydraulic expansion device constructed 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 individual expansion elements 10, 12, 14 and a hydraulic fluid supply conduit connected to a source 16 of pressurised hydraulic fluid, the conduit comprising respective bores 18, 20, 22 extending axially through the expansion elements 10, 12, 14.

1 In Figure 1, three different types of individual expansion elements 10, 12 and 14 are illustrated but, in each case, each expansion element comprises a rigid cylindrical member having an external diameter which is slightly less than the internal diameter of the shaft into which it is to be inserted. Each expansion element 10, 12 and 14 is provided with a pair of axially spaced apart circumferential recesses within which are located respective sealing rings 24 and 26 having an outside diameter slightly greater than the internal diameter of the shaft into which the device is to be inserted. Each element also includes a radially extending fluid supply bore 28 communicating between the respective axial bore 18, 20, 22 in each element and a reduced diameter radially outer surface thereof at a position intermediate the sealing rings 24-26.

Each expansion element 10, 12 and 14 is provided at one end with a cylindrical spigot formation 30 and at its opposite end with a corresponding recess for receiving the spigot of an adjacent element. In Figure 1, the left hand expansion element 10 is as hereinbefore described and includes a sealing ring 32 received within a counter-bore at the outer face of the spigot 30 for sealing such element to the pressurised fluid source 16.

The centre expansion element 12 further includes an axially extending open ended pressure relief bore 34 opening at each of its ends into an annular chamber 36 provided respectively in the end face of its spigot 30 and in the end face of its recess. A radially extending pressure relief bore 38 communicates between said axial bore 34 and the radially outer surface of the element. The right hand expansion element 14 includes further radially extending fluid supply bores 40 communicating between its axial bore 22 and its sealing rings 24-26 and 6 is provided with a sealing closure plug 42 at its outermost end. The respective expansion elements may be secured together by screw means 44 (as shown between the left hand expansion element 10 and the centre expansion element 12) or by welding 46 (as shown between the centre expansion element 12 and the right hand expansion element 14) or by any other suitable securing means. The left hand expansion element 10 is secured to the fluid source 16 as by screw means 44.

The assembly of expansion elements 10, 12 and 14 thus provides a rigid expansion device which may be inserted in a hollow shaft for radially outwardly expanding the wall thereof at axially spaced apart locations. Pressurised fluid from the source 16 is conducted via the axial bores 18, 20, 22 and the radially extending bores 28 to the annular spaces defined between respective pairs of sealing rings 24-26, the adjacent interior shaft wall and the radially outer surface of each expansion element. Additionally, in the right hand expansion element 14, the pressurised hydraulic fluid expands the sealing rings 24 and 26 radially outwardly to effect a more efficient sealing connection with the interior wall of the shaft.

An alternative embodiment of hydraulic expansion device is shown in Figure 2 wherein like reference numerals refer to like parts hereinbefore described. In this construction, each radially extending bore 28 communicates with the radially outer surface of each expansion element 50, 52, 54 at a reduced diameter portion 56 thereof at a position between a sealing ring 58 on one element and a sealing ring 60 on an adjacent element. In Figure 2 different means of connection are shown between adjacent expansion elements; thus the left 7 1 hand element 50 is connected to a spacer 62 (with its own central fluid supply bore 64 and sealing ring 58) in between the element 50 and the pressurised fluid source 16 by welding 66 whereas the left hand element 50 is secured to the centre element 52 by a screw threaded connection 68. The centre element 52 is secured to the right hand element 54 by a bayonet connection 70.

A still further embodiment of hydraulic expansion device is shown in Figure 3 of the drawings wherein like reference numerals refer to like parts hereinbefore described. In this construction, an annular peripheral recess is defined between adjacent expansion elements 72 or between an expansion element 72 and a spacer element 74 or 76 each having respective axial bores 78 and 80 therethrough communicating with the hydraulic fluid source 16. Within each peripheral recess 82 there is located a radially outwardly expandable elastomeric sleeve 84 defining an annular space 86 between it and the radially outer surface of the recess 82 whereby pressurised hydraulic fluid supplied thereto by the radially extending bore 28 expands such sleeve radially outwardly of the expansion element. The right hand expansion element 72 shown in Figure 3 includes a further stabiliser sleeve 88 within the recess 82 and is provided with a port 90 through which hydraulic fluid may pass into the annular space 86 for radially outwardly expanding the sleeve 84. To improve sealing between the sleeve 84 and the expansion element, the sleeve 84 is provided with axially outwardly extending annular projections 92 engaged with corresponding recesses in an adjacent part of the expansion element. All of the expansion elements 72 and spacer elements 74, 76 are secured to one another and to the fluid source 16 as by a screw threaded connection 94.

8 4L A still further embodiment of hydraulic expansion device is shown in Figure 4 of the drawings wherein each of the expansion elements 96 is axially spaced from an adjacent element by an interconnecting portion 98 of fluid supply conduit. In this construction, each expansion element 96 is provided at each of its ends with a counter-bore 100 within which is sealingly engaged the tapered end 102 of an interconnecting portion 98 of the supply conduit. As illustrated, the counter-bore 100 receives a screw threaded bush 104 engaged about an adjacent end of a conduit portion 98 and screwed into the counter-bore; the bush 104 itself being counter-bored at its axially inner end to receive a sealing sleeve 106 also screw threaded onto the conduit portion 98 with the screw thread of the sleeve 106 being of opposite hand to that of the screw thread of the bush 104.

Although not shown in the Figure 4 construction, a radially extending fluid supply bore (similar to the corresponding bore 28 shown in Figures 1 to 3) communicates between the axial bore 108 of each expansion element 96 and the annular space defined between a pair of sealing rings 110 on each element, the adjacent interior wall of the shaft and the radially outer surface of the element.

A hydraulic expansion device constructed in accordance with the invention thus enables simultaneous radially outward expansion of a hollow shaft at a plurality of axially spaced apart locations and may be built up of individual expansion elements according to the required number and spacings of the radially outwardly expanded locations in the shaft. The device is thus particularly suitable for use in the fabrication of a camshaft wherein a plurality of individual camshaft 2 9 elements such as cams, gears, bearings etc. are secured about the shaft at a plurality of axially spaced apart locations; the radially outward expansion of the shaft wall effecting the securing of each said camshaft element to the shaft.

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Claims

1. 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 individual hydraulic expansion elements and a hydraulic fluid supply conduit; means for sealing said elements to the interior wall of the shaft and a radially extending fluid supply bore in each said expansion element communicating between said supply conduit and the radially outer surface of said element for applying hydraulic pressure to the adjacent wall of the hollow shaft.

2. A hydraulic expansion device as claimed in Claim 1 wherein each said expansion element includes a pair of axially spaced apart sealing means; said radially extending bore communicating between an axial bore in said element and the radially outer surface thereof intermediate said sealing means, said axial bore in each said expansion element forming a part of said fluid supply conduit.

3. A hydraulic expansion device as claimed in Claim 1 wherein, in an adjacent pair of said expansion elements, one of said elements includes sealing means axially spaced apart from the sealing means of a said adjacent said expansion element; said radially extending bore in one of said expansion elements communicating between an axial bore in said element and the radially outer surface thereof intermediate said sealing means, said axial bore in said expansion element forming a part of said fluid supply conduit.

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4. A hydraulic expansion device as claimed in Claim 1 wherein, in an adjacent pair of said expansion elements, an annular peripheral recess is defined between said elements within which is located a radially outwardly expandable sleeve; said radially extending bore in one of said expansion elements communicating between an axial bore in said element and said sleeve, said axial bore in said expansion element forming a part of said fluid supply conduit.

5. A hydraulic expansion device as claimed in any one of the preceding claims wherein, in an adjacent pair of expansion elements, an end of one said element comprises a spigot received within a complimentary recess at the end of the adjacent element.

6. A hydraulic expansion device as claimed in any one of Claims 1 to 5 wherein each of said expansion elements is a rigid member and all of said expansion elements are connected together adjacent one another to form a rigid unit throughout the length of the device.

7. A hydraulic expansion device as claimed in any one of the preceding claims wherein adjacent said expansion elements are screw threadedly engaged with one another.

8. A hydraulic expansion device as claimed in any one of Claims 1 to 6 wherein adjacent said expansion elements 25 are welded to one another.

9. A hydraulic expansion device as claimed in either one of Claims 1 or 2 wherein each of said expansion elements is axially spaced from an adjacent said element by an interconnecting portion of said fluid supply 30 conduit.

12 A

10. A hydraulic expansion device as claimed in any one of the preceding claims wherein each said expansion element is 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 each said expansion element is provided with a radially extending pressure relief bore.

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

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

14. A hydraulic expansion device constructed and arranged substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.

15. A hydraulic expansion device constructed and arranged substantially as hereinbefore described with 20 reference to Figure 4 of the accompanying drawings.

16. 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.

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

Pubhsried 19813 at The Patent, Offife. Sta' c House. 6671 High 1-1c.iborn. London WC1R 4TP. Further copies may be obtained from The Patent Office.

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