GB2200974A

GB2200974A - Hydrodynamic transmissions

Info

Publication number: GB2200974A
Application number: GB08730128A
Authority: GB
Inventors: Hans Lindenthal
Original assignee: JM Voith GmbH
Current assignee: JM Voith GmbH
Priority date: 1986-12-24
Filing date: 1987-12-24
Publication date: 1988-08-17
Also published as: JPS63186041A; IT1211625B; GB8730128D0; DE3644505C2; DE3644505A1; IT8768122A0

Abstract

In order to insulate sound from vibrations or oscillations of an internal-combustion engine from being transmitted through solid bodies to a connected drive element, a hydrodynamic transmission (3) is used which has a resilient bearing means (10) for a secondary shaft (9) within the transmission. The bearing means (10) is provided with an annular hollow or solid insert (15) made of resilient material. However, no part associated with the secondary side has metallic contact with the primary side of the transmission. In this manner, not only is the torque transmitted solely by of the working fluid of the transmission with simultaneous attenuation of rotary oscillations, but sound emission from a crank-shaft (1) into the transmission (3) is totally suppressed. The means (10) includes a self-aligning roller bearing within a sleeve (11) between which and a projection (14) of the transmission housing the insert (15) is located. The primary rotor (5) is connected to the crankshaft (1) and defines two bladed cavities (6) cooperating with the bladed cavities (7) of a secondary rotor (8). The rotor (8) is connected to the secondary or output shaft (9). Adjustable gaseous pressure may be applied within the insert (15). <IMAGE>

Description

HYDRODYNAMIC TRANSMISSIONS This invention relates to hydrodynamic transmissions.

The publication Cr137 "Voith-Turbokupplungen fuur Verbrennungskraftmaschinen" (Voith Turbo-transmission for internal-combustion engine) discloses a hydrodynamic transmission comprising a primary rotor and a secondary rotor which are mounted respectively on primary and second shafts and are disposed in a common housing in which they are operatively coupled, in use, by a working fluid.

It is known that internal-combustion engine generate oscillations. These are not only audible airintake noises and sound waves from the exhaust system, but above all vibrations and rotary oscillations of the entire unit. In order to attenuate vibrations of the unit, successful use is made of resilient suspensions and silencers in the pipelines against sound emission, frequently complemented by the installation of the unit in sound-absorbent chambers or by casing with soundabsorbing hoods.

Resilient couplings, particularly those with rubber elements, are known for attenuating rotary oscillations. However, they frequently have an unsatisfactory service life, due to adverse ambient conditions such as, for example, high ambient temperature. The use of steel spring transmissions as a solution is suggested in the publication ZEV - Glasers Annalen 110 (1986) No. 6/7. Although these may provide a satisfactory service life and satisfactory attenuation, they heat up during service and have to be cooled, for example by the engine oil.

Even with special measures, transmissions as mentioned above tend to have little capacity to compensate for angular displacements on the secondary side of the transmission which occur due to the engine vibrations.

A hydrodynamic transmission of the type mentioned above is known from German Offenlegungsschrift 24 49 313, wherein the respective shafts for the primary and secondary have rotors mutually separate bearing means.

The latter are located respectively on the input side and on the output side of a housing enclosing the transmission. The rotors are placed opposite one another, without contact, in a transmission chamber.

This transmission also permits suppression of rotary oscillations between the input and output shafts.

However, since both shafts are mounted directly in the common housing, sound can be transmitted through the housing from the input side to the output side.

Although the fluid transmission known from the publication Cr137 mentioned above presents optimum attenuation of rotary oscillations, it permits no angular displacement of the secondary shaft.

For specific applications, for example for the use of internal-combustion engines in ships for specific purposes, thère is a desideratum for the drive installation to provide not only attenuation of the vibrations and rotary oscillations emanating from the engine, but additionally for total insulation of the ship's hull from solid-transmitted sound which emanates from the drive installation. Transmissions of the known type fail to fulfill this additional desideratum.

The invention aims to provide hydrodynamic transmissions in which not only rotary oscillations, but also transmission of sound through solid components from the primary side to the secondary side of the transmission is suppressed.

According to one aspect of the present invention, there is provided a hydrodynamic transmission comprising a primary rotor and a secondary rotor which are mounted respectively on primary and second shafts and are disposed in a common housing in which they are operatively coupled, in use, by a working fluid, the secondary shaft being supported in a resilient bearing means which is axially and radially flexible and is angularly moveable, and the secondary shaft and rotor having no metallic contact with the primary rotor and parts that rotate therewith.

The inventor has appreciated that translational movements of an engine can in fact be largely absorbed by resilient suspension elements, and that rotary oscillations can be attenuated satisfactorily. It has been found that sound emissions from a crankshaft, particularly, and via an engine housing through the transmission, may possibly reach a gearbox via articulated shafts and be radiated into a ship's hull by the drive elements involved. Embodiments of the invention may employ fluid transmissions having features which, due to their typical construction and function, provide optimum attenuation of rotary oscillations.

However, in contrast to these embodiments, in known fluid transmission, the secondary rotor is typically mounted directly in the primary rotor and/or in the engine crankshaft.

The use of resilient elements for fastening transmission components is known per se from German Auslegeschrift 15 25 379. So-called tolerance rings are disclosed there for fastening the two transmission rotors. However, the latter have the purpose of establishing a rotationally integral connection between the hub region of the rotors and the relevant shaft regions. The transmission of the torque is then supposed to occur via the frictional engagement produced, and under extreme service conditions, a positive connection is supposed to transmit the circumferential force with great play. The tolerance rings are accordingly not resilient elements in the sense of the present invention, for insulating the transmission of sounds through solid bodies, but simply resiliently deformable elements with a fixed installation state for bridging differences in diameter.Moreover, the tolerance rings of the known transmission are not located in the region of the bearing means. They are therefore, similarly to the bearing means according to German Offenlegungsschrift 24 49 313, not capable of preventing the passage of solidtransmitted sound from the input shaft to the output shaft.

By contrast, the secondary rotor in embodiments of the invention is mounted not rigidly, but resiliently in the stationary transmission housing. The bearing means of the secondary shaft of the transmission is provided with a resilient casing for this purpose.

Although resilient bearing means are already known per se (German Offenlegungsschrift 28 19 366), they have not hitherto been applied between the primary and secondary rotors in hydrodynamic transmissions. It was feared that the gaps between the end faces of the rotors would have to be made so large that an excessive minimum slip, and therefore uneconomic service, was to be expected.

However, this is not so in practice, because in the meantime possibilities have become known to compensate losses due to large gaps, for example by a thinner construction of the blades and sharpening the blade ends, and also by a slight enlargement of the transmission diameter. The gaps are enlarged in comparison to typical known transmissions to the extent which corresponds to the resilient yielding property of the casing. It may be advantageous for this purpose to make the front open end face of at least one of the two rotors outwardly conical, so that a gap is produced which is only wider than the known construction on the radial outside. The yielding property of the resilient bearing means in the radial direction is also taken into consideration in the construction of the radial gaps.

It is thereby possible to allow the secondary rotor to have a play for movement within the transmission to permit movements and/or vibrations emanating from a respective engine to be compensated. The capacity of the transmission to transmit torque need not be impaired by the capacity for movement of the secondary rotor, because the flux of force between the primary rotor and the secondary rotor is effected solely by the work medium of the transmission, i.e. without contact. Absolute absence of metallic contact between the primary and secondary components of the transmission is therefore achieved by the resilient bearing means of the secondary rotor and of the secondary shaft within the transmission.It can consequently fulfill the additional function of insulation against solidtransmitted sound between an engine crankshaft artd downstream elements of a drive installation, articulated shafts or gearboxes, for example.

Preferred features of the invention are disclosed in the subordinate Claims 2 to 16 appendant hereto.

Preferably, the primary and secondary rotors define at least one toroidal chamber which is filled with working fluid, in use. The bearing means is preferably disposed within said housing. Advantageously, the inside width is disposed within said housing.

It is preferable to use a sliding bearing arrangement as bearing means of the secondary shaft and of the secondary rotor in the transmission, and to use a casing made of permanently resilient plastics material resistant to the working medium of the transmission and resistant to ageing, around the sliding bearing arrangement, as a resilient element. The casing may be yielding in the radial and axial directions and also with angular mobility. The resilient bearing means of the secondary shaft is preferably located close to or in a region of a plane of symmetry of the transmission perpendicular to the longitudinal axis of the transmission. A single-flow construction which corresponds to a known transmission type, that is to say with a single toroidal chamber, may be used as fluid transmission.

However, in a preferred embodiment, the transmission is constructed as a double transmission with two simultaneously pressurisable chambers. A transmission of this construction is known per se from GB-PS 797,153. The rotors are not mutually connected via a mutual bearing means. However, the constitution of the bearing means, and whether the latter admits a radial, axial and angular mobility, is not disclosed. In preferred embodiments of the invention, an alternate enlargement and reduction of the gap at the mutually facing end faces of the rotors is produced during the relative movements between the primary rotor and the secondary rotor, so that only minimum sacrifice is incurred by losses in the gaps.

It is furthermore possible, by an angularly mobile construction of the bearing means of the secondary shaft and the secondary rotor within the transmission, to connect an upward output shaft leading on from the transmission to a gearbox, for example, directly to the secondary shaft, without using a flexible joint at the transmission end of the output shaft. The output shaft need therefore exhibit only a single flexible joint on the side facing the gearbox, and also preferably a lowfriction length compensation means, by means of rollers for example. A still more extensive sound insulation of the drive installation may further consist in that a shaft leading to the gearbox and/or away from the gearbox communicates with a further rotationally resilient transmission, the transmission halves of which exhibit no metallic contact between themselves.

For a better understanding of the invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawing, the single figure of which shows a drive installation, in longitudinal section.

The illustrated drive installations, for example, for a ship's drive having an internal-combustion engine, the crankshaft 1 of which is mounted in an engine housing 2. A hydro- dynamic transmission 3 is located in a non-rotatable housing 4 attached to the engine housing 2.

The transmission 3 comprises a primary rotor 5 which is connected by flanges to the crankshaft 1 and defines two bladed cavities 6 which with corresponding bladed cavities 7 of a secondary rotor 8 form two toroidal chambers. The secondary rotor 8 is secured to a secondary shaft 9 which exits from the transmission housing 4 through a central bore and is provided with an external flange 9a. The secondary shaft 9 supporting the secondary rotor 8 has a bearing arrangement 10. The latter may be a single sliding bearing, or a unit comprising a plurality of bearings. In the illustrated case, the bearing 10 is constructed as a self-aligning roller bearing and is housed within a bearing sleeve 11.

The centre of the bearing 10 is located substantially in a plane of symmetry 12 of the transmission 3 which is perpendicular to the axis of rotation of the transmission. A seal element 13 seals against losses of working fluid or lubricant out of the interior of the transmission and is disposed between the bearing sleeve 11 and the secondary shaft 9. A resilient insert 15 is arranged between a tubular projection 14 of the transmission housing, which projects towards the radially inner central region of the transmission, and the bearing sleeve 11. The insert 15 may be a solid annular body, or, as illustrated, a casing of partially hollow construction internally, which allows the bearing sleeve 11 with the secondary shaft 9 and with the secondary rotor 8 play for movement within the transmission.

The gaps 16 between the bladed and mutually facing open end faces of the blade cavities 6 and 7 are constituted so that no mutual contact of the rotors occurs, for the range of movement of the secondary rotor 8 permitted by the resilient casing 15. If the bearing 10 is constructed as a self-aligning bearing, it is advantageous to make the end face of at least one of the two rotors of conical construction such that the gap 16 widens radially outwards, as illustrated. In the illustrated transmission construction having two toroidal chambers, when there is a relative angular displacement, the gap between two rotors is reduced when the gap on the opposite side of the rotors is enlarged. An appreciable loss of power due to excessive gaps in the torque transmission means is prevented by this means.

An output shaft 20 is installed between the transmission 3 and a further element (not shown) of the drive installation, for example a downstream gearbox. It may be constructed as a tubular shaft and carries on the side remote from the transmission a universal joint 21 with a device 22 to compensate major differences in length, resulting from deformations or thermal expansions. In order to develop the insulating effect against transmission of sound through solid bodies, which is demanded of the illustrated transmission, it is particularly advantageous if this length compensation is associated with the weakest possible axial displacement forces. A device is therefore provided which is known per se as a "Tripod shaft", having rollers 24 with sliding bearings arranged on the circumference of a hub 23, which can roll axially in a sleeve 25 with longitudinal grooves. The gearbox (not shown) is connected to the joint fork 26 of the flexible joint 21.

Rotary oscillations generated by the internalcombustion engine are virtually totally eliminated by the illustrated hydrodynamic transmission, in a known manner.

This comes about because the primary and secondary rotors are connected not by metallic contact, but only by through the body of the working fluid. The translational movements of the internal-combustion engine during service are intercepted, as is known, by its resilient suspension, although not all the movements are suppressed. The resilient casing 15 of the bearing 10 on the secondary shaft 9 of the transmission keeps the vibrations and movements still transmitted by the engine housing 2 away from the drive installation downstream of the transmission. Moreover, the solid-transmitted sound waves which also emanate from the crankshaft 1 of the internal-combustion engine do not reach the shaft 20 and the elements driven by it, due to the absence of solid contact between the primary and secondary sides of the transmission.The same principle is therefore employed for the suppression of the solid-transmitted sound as for the elimination of the rotary oscillations.

Due to the construction of the transmission with flexible bearing means, it is possible to omit a second joint, corresponding to the joint 21, at the point of connection between the secondary shaft 9 and the shaft 20. The resilient casing 15 itself absorbs angular movements and slight displacements in the longitudinal axis of the transmission resulting from vibrations of the internal-combustion engine. Major longitudinal displacements, which arise in the context of assembly operations, for example, are absorbed by the length compensation means 22 in the output shaft 20.

In order to prevent contact between the rotors even in the event of extremely powerful shocks in the drive installation, stops 27, which are provided between the bearing sleeve 11 and the projection 14, are effective in the radial and axial directions and may be provided with stop surfaces made of resilient material.

The resilient casing 15 may also have pressuretight chambers 28 or be capable of being filled with gaseous pressurised medium. By this means it is possible to vary the resilience of the casing 15 by applying adjustable pressure. A seal element 29 may also be provided between the two rotors 5 and 8, which is effective is. the case of mutual radial offsetting.

The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification and/or drawings, or to any novel one, or any novel combination, of the steps of any method or process disclosed herein.

Claims

CLAIMS:

1. A hydrodynamic transmission comprising a primary rotor and a secondary rotor which are mounted respectively on primary and second shafts and are disposed in a common housing in which they are operatively coupled, in use, by a working fluid, the secondary shaft being supported in a resilient bearing means which is axially and radially flexible and is angularly moveable, and the secondary shaft and rotor having no metallic contact with the primary rotor and parts that rotate therewith.

2. A transmission according to Claim 1, wherein the primary and secondary rotors define at least one toroidal chamber which is filled with working fluid, in use.

3. A transmission according to Claim 1 or 2, wherein the bearing means is disposed within said housing.

4. A transmission according to Claim 1, 2 or 3, wherein the inside width of the gaps existing between the two rotors is enlarged substantially by the yielding property of the resilient bearing means.

5. A hydrodynamic transmission according to Claim 1, 2, 3 or 4, wherein the resilience of the bearing means is provided by a resilient casing disposed around a sliding bearing.

6. A hydrodynamic transmission according to Claim 5, wherein the resilient casing of the bearing means comprises a permanently resilient plastics material, for example, a heat-resistant plastics material resistant to the working medium of the transmission.

7. A hydrodynamic transmission according to Claim 5 or 6, wherein the resilient casing yields in axial and radial directions and also has angular mobility.

8. A hydrodynamic transmission according to Claim 5, 6 or 7 wherein the resilient casing is mounted on a projection which is integral with the housing and extends into the interior region of the transmission.

9. A hydrodynamic transmission according to any of the preceding claims, wherein the end face of at least one of the two rotors is of conical configuration in order to form a gap which widens radially outwards between the opposing end faces of the rotors.

10. A hydrodynamic transmission according to any of the preceding claims, wherein the bearing means is arranged close to or in the region of a plane of symmetry of the transmission perpendicular to the longitudinal axis of the transmission.

11. A hydrodynamic transmission according to Claim 5 or to any of Claims 6 to 10 as appendant thereto, wherein the bearing means has bearing components enclosed by a bearing sleeve and braced in the primary rotor through the resilient casing.

12. A hydrodynamic transmission according to any of the preceding claims, constructed as a double transmission with two simultaneously pressurised chambers.

13. A hydrodynamic transmission according to Claim 5 or to any of Claims 6 to 12 as appendant thereto, wherein the resilient casing of the bearing means is provided with pressure-tight cavities and may be pressurised with a pressurised medium.

14. A hydrodynamic transmission according to any of the preceding claims, wherein the bearing means is provided with stop means to limit radial and axial movement.

15. A hydrodynamic transmission substantially as hereinbefore described with reference to the accompanying drawing.

16. A drive installation comprising a prime mover, a driven element, and a hydrodynamic transmission which is disposed between the prime mover and the driver element and is in accordance with any of the preceding claims.