GB2374636A

GB2374636A - Engine and transmission unit with extension frame for reduced noise and vibration

Info

Publication number: GB2374636A
Application number: GB0206299A
Authority: GB
Inventors: Howard Lawrence
Original assignee: Perkins Engines Co Ltd
Current assignee: Perkins Engines Co Ltd
Priority date: 2001-03-20
Filing date: 2002-03-18
Publication date: 2002-10-23
Anticipated expiration: 2022-03-18
Also published as: GB0206299D0; US20020134193A1; GB0106859D0; GB2374636B

Abstract

An automotive engine and transmission unit assembly has an extension frame 1 fixedly connected to the cylinder block 2 and the cylinder head 14 of the engine 3 and to the transmission unit 17, which is itself attached to the cylinder block 2. The extension frame 1, which may include an apron 31 connected to a side surface 6 of the cylinder block 2, increases the natural frequency of vibration of the engine and transmission unit assembly, eg to greater than 250 Hz, thereby reducing undesirable noise. The extension frame 1 may include, in addition to integral apron 31, inner and outer box-like beams 19, 20, an upright strut 21, a top rail 23 and a diagonal strut 22 extending between the top rail 23 and the beams 19, 20. Alternatively, the extension frame may be independent of the apron 31 or the apron may be absent.

Description

1 A CYLINDER BLOCK EXTENSION FRAME

3 Technical Field

5 This invention relates to an engine and transmission 6 unit assembly having reduced noise and vibration.

7 The invention also relates to a method of reducing 8 noise and vibration from an engine and transmission 9 unit assembly.

11 Background

13 Internal combustion engines are a source of noise and 14 vibration which may be undesirable. The noise and 15 vibration results from the vibration frequencies 16 created by the combustion events in an engine. It is 17 desirable for the bending (beaming) frequency of an 18 engine and transmission unit assembly to be outside 19 of the firing frequency of the engine so that the 20 firing frequency does not excite the bending mode.

1 250 Hz is generally regarded as a critical frequency 2 below which undesirable noise and vibration may 3 occur.

5 Japanese Patent Application No 2185655 describes a 6 bracket which functions to rigidly connect an engine 7 transmission unit with a cylinder block of an engine.

8 Use of the bracket improves the rigidity of an engine 9 assembly and increases the natural frequency of 10 vibration of the engine assembly.

12 The present invention sets out to raise the bending 13 frequency of an engine and transmission unit assembly 14 to obviate or mitigate any undesirable noise and 15 vibration therefrom.

17 Summary of the Invention

19 According to the invention there is provided an 20 engine and transmission unit assembly comprising an 21 engine including a cylinder block and a cylinder 22 head, a transmission unit attached to the cylinder 23 block, and an extension frame connected to the 24 cylinder block, the cylinder head and the 25 transmission unit to increase the natural frequency 26 of vibration of the engine and transmission unit 27 assembly.

29 The invention also extends to a method of reducing 30 transmitted noise and vibration from an engine 31 including a cylinder block, a cylinder head and a

1 transmission unit, comprising the steps of providing 2 an extension frame, and connecting the extension 3 frame to the cylinder block, the cylinder head and 4 the transmission unit to increase the natural 5 frequency of vibration of the engine and transmission 6 unit assembly.

8 Brief Description of the Drawings

10 Various embodiments of the invention will:now be 11 described, by way of example only, having regard to 12 the accompanying diagrammatic drawings in which: 14 Figure 1 is an isometric view of an engine and 15 transmission unit assembly in which the cylinder 16 block of the engine is fitted with an apron (shown 17 partly cut away), the apron including an extension 18 frame in accordance with the invention; and 20 Figure 2 is a side view of the engine, 21 transmission unit and apron and extension frame of 22 Figure 1.

24 Detailed Description

26 As shown in the drawings, an engine and transmission 27 unit assembly in accordance with the invention is 28 made up of an extension frame 1 extending between a 29 cylinder block 2, a cylinder head 14 and a 30 transmission unit 17. The extension frame 1 31 increases the specific stiffness of the assembly of

1 engine 3 and transmission unit 17 thereby increasing 2 the natural bending/torsion frequency of the engine 3 and transmission unit assembly to reduce noise and 4 vibration therefrom. In a preferred embodiment the 5 extension frame l includes an apron 31 mounted to a 6 first side wall 6 of a cylinder block 2 of the engine 7 3. The apron 31 is a tray-like panel and can extend 8 over part or all of the side wall 6.

10 In the illustrated embodiment of the invention, the 11 cylinder block 2 is a substantially conventional 12 cylinder block to which an apron 31 may be attached.

13 However, the extension frame 1 may be adapted for use 14 with various cylinder block types without departing 15 from the scope of the invention.

17 The cylinder block 2 includes a cylinder block base 18 5, the cylinder block first side wall 6, a cylinder 19 block second side wall 7 substantially parallel with 20 the cylinder block first side wall 6, a cylinder 21 block front end wall 8 and a cylinder block rear end 22 wall (not shown), all upstanding from the cylinder 23 block base 5.

25 The cylinder block rear end wall is provided with a 26 bearing plate 11 which projects laterally outwards 27 from the first side wall to provide for attachment 28 of the transmission unit 17 and other components such 29 as a starter motor or fuel pump (not shown). The 30 bearing plate 11 has an inner face 12 disposed

1 towards the side wall 6 and an outer face 13 disposed 2 away from the side wall 6.

4 The cylinder block 2 is provided with a cylinder head 5 cover 15 mounted on the cylinder head 14. A sump 10 6 abuts the cylinder block 2.

8 The cylinder block 2 has a flange 16 at the cylinder 9 block base 5 along the first and second side walls 6, 10 7. The flange 16 is provided with flange holes 25 11 for attaching the apron 31 to the cylinder block 2 as 12 shall be explained more fully below. The flange 13 holes 25 also serve to receive fasteners 26 for 14 securing the sump 10 to the cylinder block base 5.

15 The fasteners 26 may be any suitable fasteners.

17 The extension frame 1 is substantially rigid in 18 construction and, as indicated above, extends between 19 the cylinder block 2, the cylinder head 14 and the 20 transmission unit 17. Preferably, the extension 21 frame includes an integral apron 31 and a generally 22 triangulated portion including frame members 18, 21, 23 22 arranged to brace from spaced apart points 32, 33 24 on the apron 31 to a point 34 at, or substantially 25 towards, a spaced apart end 35 of the transmission 26 unit 17.

28 In the illustrated example the extension frame 1, 29 which includes the apron 31 as an integral part 30 thereof, is additionally made up of a number of frame 31 members, including a transverse double box-like beam

1 18 having a truncated inner box-like beam 19 and an 2 outer box-like beam 20, an upright strut 21 extending 3 between the transverse double box-like beam 18 and an 4 extension frame top rail 23, and a diagonal strut 22 5 extending between the top rail 23 and the transverse 6 double box-like beam 18.

8 The frame members, including the inner box like beam 9 19, the outer box-like beam 20, the upright strut 21, 10 the diagonal strut 22 and the top rail 23 j are 11 preferably formed from a sheet-metal, but may be 12 formed from any other suitable material. The parts 13 making up the extension frame 1 may be formed 14 integrally with the apron 31, as top rail 23 in the 15 illustrated example, or suitably attached to the 16 apron 31 by welding or other means, as outer box-like 17 beam 20 in the illustrated example. It is envisaged 18 that at least some of the parts making up the 19 extension frame 1 will need to be fabricated 20 separately and subsequently joined to the apron 31 or 21 one to another.

23 Preferably, the extension frame 1 is mounted between 24 the cylinder block 2, the cylinder head 14 and the 25 transmission unit 17 either side of the bearing plate 26 11 so that the upright strut 21 is disposed adjacent 27 the bearing plate inner face 12 while the diagonal 28 strut 22 is located externally of the bearing plate 29 outer face 13. The apron 31, the upright strut 21 30 and the diagonal strut 22 may be secured to the

1 bearing plate 11 for increased integrity of 2 construction if required.

4 The apron 31 is secured to the cylinder block flange 5 16 by the fasteners 26 which, as indicated above, 6 simultaneously secure the sump 10 to the cylinder 7 block 2. The first outer box-like beam member 20 8 extends rearwardly of the cylinder block 2 towards 9 the transmission unit 17. The second inner box-like 10 beam member 19 is truncated between the cylinder 11 block 2 and the transmission unit 17. The purpose of 12 the second inner box-like beam 19 is to stiffen the 13 structure and suitably space the extension frame 1 in 14 relation to the cylinder block side wall 6. It may 15 be found in some installations that the second inner 16 box-like beam 19 is not required. It may also be 17 found that the first outer box-like beam 20, or other 18 constituent parts of the extension frame 1 or apron 19 31, may provide suitable mounting points for the 20 engine and transmission mountings.

22 In use, the apron 31 of the extension frame 1 is 23 attached to the cylinder block 2 with fasteners 26 as 24 previously described to lower attachment points. The 25 extension frame 1 is also attached to the cylinder 26 head 14 at upper attachment points at or close to the 27 top rail 23 by fasteners 24. The apron 31 may also 28 be adhesively attached or otherwise conventionally 29 fastened at other points on the cylinder block or the 30 cylinder head as may be desired for improved 31 integrity of construction.

1 The extension frame 1 extends rearwardly of the 2 cylinder block 2 and in the present embodiment is 3 secured to the transmission unit 17 at the double 4 box-like beam 18 disposed adjacent the diagonal strut 5 22. 7 In an alternative embodiment of the invention, not 8 illustrated, the extension frame 1 can be employed 9 independently of an apron 31 applied to the cylinder 10 block side wall 6, 7 or in the absence of:an apron.

11 In such an embodiment, the extension frame 1 may be 12 made up as a generally triangulated frame of frame 13 members for direct attachment to the engine 3 at 14 spaced apart attachment points on the cylinder block 15 2 and the cylinder head 14 (which points would 16 generally correspond to upper and lower points 33, 32 17 respectively on the apron 31 of Figure 2) to a point 18 34 at, or substantially towards, a spaced apart end 19 35 of the transmission unit 17.

21 Industrial Applicability

23 The extension frame 1 of the present invention serves 24 to increase the natural bending/torsion frequency of 25 an engine to reduce transmitted noise and vibration.

26 For example, in a conventional engine, the critical 27 bending/torsion frequency giving rise to transmitted 28 noise is considered to be approximately 250 Hz while 29 a typical conventional cylinder block gives rise to a 30 frequency of approximately 300 Hz. A transmission 31 unit 17 in a typical conventional engine reduces the

1 overall frequency by approximately 80 Hz to below the 2 critical frequency of 250 Hz thereby giving rise to 3 significant transmitted noise and vibration.

4 However, where the extension frame 1 of the invention 5 is disposed between the cylinder block 2, the cylinder head 14 and the transmission unit 17, the 7 frequency is increased to above the critical 8 frequency of 250 Hz to increase the natural 9 bending/torsion frequency and to thereby reduce noise lo and vibration therefrom.

12 The extension frame 1 therefore forms a bridge 13 between the cylinder block 2, the cylinder head 14 14 and the transmission unit 17. The Applicants have 15 found that the natural frequency of vibration of the 16 engine and transmission unit assembly is increased by 17 the fixed connection of the extension frame 1 to the 18 cylinder block 2, the cylinder head 14 and the 19 transmission unit 17. The extension frame 1 20 increases the second moment of area between the 21 cylinder block 2, cylinder head 14 and the 22 transmission unit 17 to increase the specific 23 stiffness of the engine and transmission unit 24 assembly to give rise to the increased natural 25 bending/torsion frequency.

27 It will be appreciated by those skilled in the art 28 that the extension frame 1 of the invention can be 29 modified in accordance with particular engine 30 requirements and the tuning requirements thereof to

l increase the natural bending/torsion frequency by a 2 desired amount.

4 In the given example, the parts making up apron 31 5 are envisaged as having a thickness of from about 2 6 to about 4 millimetres but thickness selection will 7 need to take into account variables such as the 8 required stiffness, ease of forming and the duty to 9 which the apron 31 and the extension frame 1 are to 10 be subjected to, taking into account the accessories 11 to be mounted thereon and whether engine mountings 12 and transmission housings are to be attached thereto.

13 The apron 31 and extension frame 1 may be reinforced 14 locally as required. The apron 31 may be flat folded 15 and bent or pressed to shape as required.

17 The apron 31 and the extension frame 1 are preferably 18 formed from high strength low alloy (HSLA) steel but 19 can also be formed from cold rolled mild steel, 20 aluminium sheet or any other material having suitable 21 characteristics. The apron 31 and the extension 22 frame 1 can be configured by laser machining or the 23 like or may be numerically controlled punch profiled.

24 The apron 31 may be folded by a brake press and deep 25 drawn for pressed features.

27 The extension frame 1 can be formed by welding or 28 otherwise joining one or more parts to form a single 29 integral apron 31 and extension frame 1.

30 Alternatively, as already indicated, the extension 31 frame 1 may be fitted to the cylinder block

1 independently of any apron. Further, the apron or 2 its constituent parts may be configured as tailored 3 blanks comprising panel parts of different thickness 4 or different metallurgy. For example, the apron 31 5 could be formed in general from a mild steel whilst 6 the extension frame 1 could be formed in part or as a 7 whole from an alloy steel.

9 The extension frame 1 of the invention finds 10 application in engine and transmission unit 11 assemblies where it is desired to reduce noise and 12 vibration therefrom. The extension frame of the 13 invention also finds application in automotive engine 14 and transmission unit assemblies where reductions in 15 noise and vibration therefrom are particularly sought 16 after.

18 The invention is not limited to the embodiments 19 herein described, which may be varied in construction 20 and detail.

Claims

1 CLAIMS

3 1. An engine and transmission unit assembly 4 comprising: 5 an engine including a cylinder block and 6 a cylinder heads 7 a transmission unit attached to the cylinder 8 block; and 9 an extension frame fixedly connected to the 10 cylinder block, the cylinder head and the 11 transmission unit to increase the natural frequency 12 of vibration of the engine and transmission unit 13 assembly.

15

2. An engine and transmission unit assembly as 16 claimed in Claim 1 wherein the extension frame

17 includes a plurality of frame members connected to 18 form a triangulated frame.

20

3. An engine and transmission unit assembly as 21 claimed in Claim 1 or Claim 2 wherein the cylinder 22 block has a surface provided with apron attachment 23 points, and the extension frame includes an apron 24 mounted on said surface.

26

4. An engine and transmission unit assembly as 27 claimed in Claim 3 wherein the extension frame 28 includes a plurality of frame members extending 29 between the apron and the transmission unit.

1

5. An engine and transmission unit assembly as 2 claimed in any preceding Claim wherein the extension 3 frame includes a first beam member extending between 4 the cylinder block and the transmission unit.

6

6. An engine and transmission unit assembly as 7 claimed in Claim 5 wherein the extension frame 8 further includes a second beam member adjacent to the 9 first beam member and serving to space the first beam 10 member from the cylinder block.

12

7. A method of reducing transmitted noise and 13 vibration from an engine including a cylinder block, 14 a cylinder head and a transmission unit attached to 15 the cylinder block, comprising the steps of providing 16 an extension frame, and fixedly connecting the 17 extension frame to the cylinder block, the cylinder 18 head and the transmission unit to increase the 19 natural frequency of vibration of the engine and 20 transmission unit assembly.

22

8. A method as claimed in Claim 7 wherein the 23 extension frame includes an apron, including the 24 steps of providing apron attachment points on a 25 surface of the cylinder block, and mounting the apron 26 on said surface.

28

9. An engine and transmission unit assembly 29 substantially as hereinbefore described with 30 reference to the accompanying drawings.

1

10. A method of reducing transmitted noise and 2 vibration from an engine substantially as 3 hereinbefore described with reference to the 4 accompanying drawings.