GB2322110A

GB2322110A - Substituting prime movers in a power train for water borne vessels

Info

Publication number: GB2322110A
Application number: GB9726833A
Authority: GB
Inventors: Anthony Rouse; David Hiscox
Original assignee: GKN Driveline Ltd
Current assignee: GKN Driveline Ltd
Priority date: 1996-12-31
Filing date: 1997-12-22
Publication date: 1998-08-19
Also published as: GB9627093D0; GB9726833D0

Abstract

A method of converting a power train comprising a first prime mover 11 of a water borne vessel, a driven member 13 in the form of a screw propeller, and a drive transmission 15 to transmit drive between the first prime mover and the driven member at a first speed ratio, wherein a second prime mover is substituted for the first prime mover and a ratio change gear box 18 is introduced into the drive transmission to provide a second different speed ratio to ensure that the driven member 13 is driven at the same speed of rotation as it was by the first prime mover, prior to substitution of the prime movers. As shown the gear box 18 comprises epicyclic gearing having a stationary sun gear 46, a plurality of planet gears 33 rotatably mounted on a carrier 36, and a ring gear 32. The input from the second prime mover 11 is connected to the carrier 36 and the output from the ring gear 32 to the input 14 of the first speed ratio gearbox 15.

Description

Title: Power Train, Drive Transmission, and Method of Conversion thereof.

Description of Invention This invention relates to a power train comprising a prime mover, a drive member and a drive transmission to transmit a drive from the prime mover to the driven member. More particularly, but not exclusively, the invention relates to a power train having a drive transmission to transmit drive from a prime mover of a water borne vessel to a drive member comprising a screw propeller thereof.

In a water borne vessel, a screw propeller of the vessel is usually designed to be rotated at a predetermined maximum speed of rotation. A prime mover of the vessel, when operating at a pre-determined speed, is arranged to drive the screw propeller at said maximum speed by means of a drive transmission, with any desired step-up or step-down of ratio between the speeds of rotation of the prime mover and of the screw propeller included in the drive transmission.

However, when the prime mover of the vessel is changed for one which is designed to operate at a different speed of rotation, for example, when changing from a spark ignition engine to a compression ignition engine, it has hitherto been necessary to change the pitch and/or diameter of the screw propeller to suit the different speed of rotation of the new power unit and still drive the vessel at, or substantially at, the same speed. In some cases it is desirable to increase the diameter of the propeller as well to increase the pitch of the propeller to provide the correct drive from a propeller which is rotated more slowly by the new prime mover. However, because of constraints imposed by the proximity of the screw propeller to the hull of the vessel it may not be possible to increase the propeller size to that desired.

Objects of the invention are to provide a power train and a drive transmission for use in a power train whereby the above mentioned problems are overcome or are reduced. Other objects of the invention are to provide a method of converting a power train incorporating a first prime mover to one incorporating a second prime mover for operation at different speeds and a method of converting a drive transmission for use in such a power train.

According to one aspect of the present invention we provide a power train comprising a prime mover, a driven member and a drive transmission, comprising an input element connected to the prime mover and an output element connected to the driven member, to transmit drive from the prime mover to the driven member wherein the drive transmission includes a ratio change gear box, having a stationary housing, to change the speed of rotation of the output element relative to that of the input element.

According to a further aspect of the present invention we provide a drive transmission, for transmitting drive from a prime mover to a driven member, comprising an input element for connection to the prime mover and an output element for connection to the driven member thereby the drive transmission includes a ratio change gear box, having a stationary housing, to change the speed of rotation of the output element relative to that of the input element.

According to another aspect of the present invention we provide a method of converting a power train comprising a first prime mover, a driven member, and a drive transmission comprising an input element connected to the first prime mover and an output element connected to the driven member, to transmit drive from the first prime mover to the driven member at a first ratio between the speeds of rotation of the first prime mover and the driven member comprising the steps of substituting a second prime mover for said first prime mover and introducing in to said drive transmission a ratio change gear box to provide a second, different, ratio between the speeds of rotation of the second prime mover and the driven member.

According to another aspect of the present invention we provide a method of converting a drive transmission, for transmitting drive from a prime mover to a driven member, comprising an input element for connection to the prime mover and an output element for connection to the driven member and there being a first ratio between the speeds of rotation of the input and output element comprising the step of introducing into said drive transmission a ratio change gear box to provide a second, different, ratio between the speeds of rotation of said input and output elements.

The first prime mover may have a first pre-determined speed of rotation and, prior to conversion may drive the driven member at a second predetermined speed of rotation whilst, after conversion, the second prime mover may have a third pre-determined speed of rotation and drive the screw propeller at said second pre-determined speed of rotation or within a pre-determined percentage of said second pre-determined speed of rotation.

Said percentage may be within plus or minus 40% and may be within plus or minus 30%, or 20%, or 15%, 10%, or 5% of said second pre-determined speed.

The driven member may comprise a screw propeller.

The ratio change gear box may comprise an epicyclic gear box.

The epicyclic gear box may comprise, disposed within the housing, a sun gear in mesh with at least one planet gear rotatably mounted on a carrier and the or each planet gear being in mesh with an internal annular gear.

The carrier and the annular gear may be drivingly connected to said input and output elements.

The carrier may be connected to the input element to rotate therewith whilst the annular gear may be connected to the output element to rotate therewith, the sun gear being connected to the housing.

Alternatively, if desired the sun gear and the annular gear may be connected to said input and output elements and the carrier being connected to the housing.

If desired other components of the ratio change gear may be connected to said input and output elements and to the housing respectively depending upon the ratio change required.

The annular gear may be provided on an inwardly facing hollow drum portion of an annular gear member, said annular gear member also comprising a stub shaft which extends away from the drum portion and being carried by the housing to project outwardly of the housing from one end thereof.

The or each planet gear may be disposed in, or substantially in, said drum portion.

The or each planet gear may be rotatably mounted on a carrier disposed in, or substantially within, said drum portion.

The carrier may be engaged with a further shaft of the gear box which extends within said drum portion and is carried by the housing to project outwardly from the housing at an end thereof which is opposite to said one end thereof.

The carrier may be connected to the further shaft to rotate therewith.

The sun gear may disposed within the drum portion and be connected to the housing, so as to be stationary therewith, by means of a stationary shaft.

The stationary shaft may extend from the sun gear towards said other end of the housing.

The stationary shaft may encircle said further shaft.

The further shaft may be carried, at or adjacent an end thereof which is closer to said one end of the housing, by the stub shaft.

Bearing means may be provided between at least one of the annular gear member and the housing, the further shaft and the housing and the further shaft and the annular gear member.

The bearing means between the housing and the annular gear member may comprise a pair of axially spaced bearings. One of said bearing may be axially aligned with a part of the stub shaft and the other of the bearing being axially aligned with a part of the annular gear member comprising, or adjacent to, the drum portion.

An embodiment of the invention will now be described in more detail by way of example with reference to the accompanying drawings wherein Figure Ia is a diagrammatic illustration of the vessel prior to conversion, Figure ib is a diagrammatic illustration of the vessel of Figure 1 after conversion and embodying the invention, Figure 2 is a side elevation of a ratio change gear box for use in the vessel of Figure 1, Figure 3 is an end view of the gear box of Figure 2 looking in the direction of the arrow A, Figure 4 is an opposite end elevation looking in the direction of the arrow B, and Figure 5 is a cross section on the line 5-5 of Figure 4.

Referring to Figure 1 a power train comprises a prime mover 11 which is drivingly connected, by a drive transmission 12, to a screw propeller 13.

The drive transmission 12 comprises an input element 14 fastened to a fly wheel F of the prime mover 11 in known manner, for example by means of a splined shaft via a torsional damping device. The input element 14 of the transmission 12 comprises a conventional input of a forward and reverse gear box 15 connected by a propeller shaft 16 to the screw propeller 13 by means of an output element 16a which may comprise a tapered keyway portion of the propeller shaft 16 in engagement with the screw propeller 13. The propeller shaft 16 has an out board bearing 17 provided in a stern tube of the vessel in conventional manner.

The gear box 15 may be provided with a step-down or step-up speed ratio if desired.

When designing the vessel 10 the pitch and diameter of the propeller 13 is chosen in association with the intended maximum speed of operation of the prime mover 11 and the intended maximum speed of the vessel in well known manner. In the preferred example the prime mover 11 prior to conversion is a spark ignition or petrol engine.

Referring now to Figure la, when it is desired to re-engine the vessel with, for example, a compression ignition or diesel engine intended to operate at a lower maximum speed, there is included in the drive transmission 12 a ratio change gear box 18 having an input 18a and an output 18b. In the present example the ratio change gear box 18 is provided externally of a bell housing 19 of the prime mover 11 so that it is inter-posed between the fly-wheel F of the prime mover 11 and the input 14 of the gear box 15. The input 18a of the ratio change gear box 16 is connected to the fly-wheel F in conventional manner, for example in the same manner as the input 14 prior to conversion, whilst the output 18b is connected to the gear box input 14 in conventional manner with any necessary adaptor provided, for example by fitting a flange to the splined gear box input 14 to fit a flanged output 18b of the ratio change gear box 18. The input element of the drive transmission 12, after conversion, comprises the input 18a of the ratio change gear box 18.

The ratio of the gear box 18 is arranged so that the screw propeller 13 is driven at the same speed of rotation by the second prime mover as it was driven by the first prime mover, prior to substitution of the prime movers.

The ratio change gear box 18 comprises a stationary, generally cylindrical, hollow housing 20 sandwiched between the bell housing 19 and the forward and reverse gear box 15 by bolts 21 passed through six equally circumferentially spaced passages of the ratio change gear box 18 and through corresponding passages in the forward and reverse gear box 15 and received in threaded apertures in the bell housing 19. If desired, the ratio change gear box 18 may be fastened to the engine utilising any suitable adapter plate as may be necessary. A spacer ring R is interposed between the gear boxes to accommodate the flanged connections 18h, 14. In this example the propeller shaft 16 is shortened to accommodate the ratio change gear box 18.

Within the housing 20 there is provided an annual gear member 25 having a generally hollow cylindrical drum portion 26 which, in the present example, has portions of progressively reducing diameter and which is connected by a transverse wall 27 to a stub shaft 28. The stub shaft 28, in the present example, is provided with a connecting flange 29 which is supported by a ball bearing 30 at one end 31 of the housing 20. The largest diameter part of the drum portion 26 is provided, on an inwardly facing surface, with an annular gear 32 which meshes with a plurality, in the present example 3, planet gears 33 which are carried by suitable bearing means 34 on shafts 35 of a carrier 36. The carrier 36 is splined, as shown at 37, to a further shaft 38 which projects outwardly of the housing 20 at an end 39 thereof opposite to the end 31. The further shaft 38 is carried in the wall of the housing 20 by a double row ball bearing 40. The further shaft 38 has a splined end part 41 which provides an input for connection with a vibration damper connected to the fly wheel F.

Encircling a part of the further shaft 38 is a stationary shaft 42 which is fixed to a flange 43 which is bolted, by a plurality of bolts 44, in a recessed extension part 45 of the housing 20 at said opposite end 39 thereof. The stationary shaft 42 is provided with a sun gear 46 which meshes with the teeth of the planet gears 33.

The housing 20 is made in two parts 20L 20b which are inter connected by a plurality, in the present example four, bolts 48. Part 20a of the housing has a bearing carrier 49 bolted thereto by 6 equally angularly spaced bolts 50 so that the smaller diameter part of the drum portion 26 is supported from the housing 20 by a further ball bearing 51 carried by the bearing carrier 49.

A plain bearing 52 is provided between a recess 53 of the stub shaft 28 and a reduced diameter nose part 54 of the further shaft 38. Spacers 55, 56 are provided between the planet carrier and portions of the annular gear member and housing respectively.

The flange 29 provides the ratio change gear box 18 with an output which is connected to the input 14 of the gear box 12.

The gear box provides a step-up ratio equal to 1+ (Number of teeth of the sun gear divided by the number of teeth of the annular gear). Typically this lies in the ratio of 1:1.2 to 1:1.7 and so accommodates typical ratios of speed reduction between a spark ignition engine and a compression ignition engine.

In operation, the prime mover 11 rotates the further shaft 38 which thus acts as an input shaft to the gear box so as to rotate the carrier and, since the planet gears are engaged with the fixed sun gear 46, the annular gear member 25 is caused to rotate in the same direction and at the desired stepped up ratio so that the propeller can be made to rotate at the same speed and direction with a lower revving diesel engine as was achieved previously with the more highly revving petrol engine.

It should be appreciated that the diameters and number of teeth of the various meshing components are chosen in conventional manner to achieve the desired step-up ratio, bearing in mind the difference between the speeds of operation of the engines.

If desired, depending upon the nature of application other components of the gear box may be connected to the input and or output shafts and the housing respectively to provide a planetary or star configuration instead of the solar configuration described above and the ratio change and direction of rotation provided may be a different step-up ratio than that described hereinbefore. If the vessel is re-engined with an engine which rotates faster than the engine which is re-placed then the ratio change gear box may be arranged to provide a step-up ratio by reversing the drive path.

Further, if desired, the gear box may be adapted to provide a reverse and forward gear and/or a plurality of forward and/or reverse ratios.

Although it is preferred that the gear box ratios of the present invention are arranged so that the screw propeller 13 is rotated at the same speed with the second engine as with the first engine if desired the propeller may be rotated at a different speed and may for example be rotated at a fixed percentage relative to the previous speed for example 40% of the previous speed or, progressively preferably, plus or minus 30%, or 20% or 15% or 10% or 5% of the previous speed. In the present example, the fixed percentage is 28.5%.

The housing is provided with a copper cooling tube 55 which extends chordally across and within the housing so as to extract heat from oil with which the gear box is filled for cooling purposes. The housing may be provided with suitable vent means and/or drain means and top up means may be provided as desired, for example, as illustrated at 56.

If desired any necessary adapter means between the various components of the power train may be provided and/or a modified bell housing may be provided.

If desired, the ratio change gear box may be provided down stream of the forward and reverse gear box so as to be disposed between the forward and reverse gear box and the propeller shaft. Furthermore, in a vessel where the propeller shaft is provided with a thrust bearing fixed to the hull of the vessel and, for example, a universal joint between the prime mover and the thrust bearing, the ratio change gear box may be provided, if desired, up-stream or down-stream of the thrust bearing or indeed the ratio change gear box itself may be fixed to the hull of the vessel and be provided with a suitable thrust bearing arrangement so as to obviate the need for a separate thrust bearing.

If desired, a ratio change gear box embodying the present invention may be provided within the bell housing or an extension of the bell housing, suitable cooling arrangements being provided accordingly.

Although the invention has been devised primarily for use in a marine vessel as described hereinbefore it may be used in other applications as desired.

The ratio change gear box itself may have other applications to that described hereinbefore.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

1. A power train comprising a prime mover, a driven member and a drive transmission, comprising an input element connected to the prime mover and an output element connected to the driven member, to transmit drive from the prime mover to the driven member wherein the drive transmission includes a ratio change gear box, having a stationary housing, to change the speed of rotation of the output element relative to that of the input element.

2. A drive transmission, for transmitting drive from a prime mover to a driven member, comprising an input element for connection to the prime mover and an output element for connection to the driven member, wherein the drive transmission includes a ratio change gear box, having a stationary housing, to change the speed of rotation of the output element relative to that of the input element.

3. A method of converting a power train comprising a first prime mover, a driven member, and a drive transmission comprising an input element connected to the first prime mover and an output element connected to the driven member, to transmit drive from the first prime mover to the driven member at a first ratio between the speeds of rotation of the first prime mover and the driven member comprising the steps of substituting a second prime mover for said first prime mover and introducing in to said drive transmission a ratio change gear box to provide a second, different, ratio between the speeds of rotation of the second prime mover and the driven member.

4. A method of converting a drive transmission, for transmitting drive from a prime mover to a driven member, comprising an input element for connection to the prime mover and an output element for connection to the driven wherein the bearing means between the housing and the annular gear member comprise a pair of axially spaced bearings.

25. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 24 wherein one of said bearing is axially aligned with a part of the stub shaft and the other of the bearings is axially aligned with a part of the annular gear member comprising, or adjacent to, the drum portion.

26. A power train substantially as herein described with reference to the accompanying drawings.

27. A drive transmission substantially as herein described with reference to the accompanying drawings.

28. A method of converting a power transmission as herein described with reference to the accompanying drawings.

29. A method of converting a drive transmission as herein described with reference to the accompanying drawings.

30. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.

19. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to any of Claims 14 to 18 wherein the sun gear is disposed within the drum portion and is connected to the housing, so as to be stationary therewith, by means of a stationary shaft.

20. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 20 wherein the stationary shaft extends from the sun gear towards said other end of the housing.

21. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 19 or Claim 20 wherein the stationary shaft encircles said further shaft.

22. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to any one of Claims 17 to 21 wherein the further shaft is carried, at or adjacent an end thereof which is closer to said one end of the housing, by the stub shaft.

23. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to any one of Claims 14 to 22 wherein a bearing means are provided between at least one of the annular gear member and the housing, the further shaft and the housing and the further shaft and the annular gear member.

24. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 23 said input and output elements and to the housing respectively depending upon the ratio change required.

14. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to any one of Claims 9 to 13 wherein the annular gear is provided on an inwardly facing hollow drum portion of an annular gear member, said annular gear member also comprising a stub shaft which extends away from the drum portion and being carried by the housing to project outwardly of the housing from one end thereof.

15. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 14 wherein the or each planet gear is disposed in, or substantially in, said drum portion.

16. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 14 or Claim 15 wherein the or each planet gear is rotatably mounted on a carrier disposed in, or substantially within, said drum portion.

17. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 16 wherein the carrier is engaged with a further shaft of the gear box which extends within said drum portion and is carried by the housing to project outwardly from the housing at an end thereof which is opposite to said one end thereof.

18. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 17 wherein the carrier is connected to the further shaft to rotate therewith.

7 where dependent directly or indirectly on Claim 4 wherein the ratio change gear box comprises an epicyclic gear box.

9. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 8 wherein the epicyclic gear box comprises, disposed within the housing, a sun gear in mesh with at least one planet gear rotatably mounted on a carrier and the or each planet gear being in mesh with an internal annular gear.

10. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 9 wherein the carrier and the annular gear are drivingly connected to said input and output elements.

11. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 10 wherein the carrier is connected to the input element to rotate therewith whilst the annular gear is connected to the output element to rotate therewith, the sun gear being connected to the housing.

12. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to Claim 10 wherein the sun gear and the annular gear are connected to said input and output elements and the carrier is connected to the housing.

13. A power train or a drive transmission or a method of converting a power train or a method of converting a drive transmission according to any one of Claims 9 to 12 wherein other components of the ratio change gear are connected to