WO1995035487A1

WO1995035487A1 - A mechanical coupling between a driving source and a load object designed for application of transducers for torque, rotation speed or angular position or a combination thereof

Info

Publication number: WO1995035487A1
Application number: PCT/SE1995/000624
Authority: WO
Inventors: Pär Gustafsson; Jan Jeremiasson; Hans Ling
Original assignee: Asea Brown Boveri Ab
Priority date: 1994-06-20
Filing date: 1995-06-01
Publication date: 1995-12-28
Also published as: SE9402158D0; SE9402158L

Abstract

A mechanical coupling between a driving source (D) and a load object (B) designed for application of measuring devices for torque, rotation speed or angular position, or a combination thereof. The coupling comprises a transducer shaft (1), which by means of joints (2, 4) is fixed on the one hand to a carrier (3) of the load object and on the other hand to a crankshaft (5) of the driving source. The attachment to the crankshaft is performed in a crater in the crankshaft end. The sensing portion (9) of the measuring device is placed with clearance in a tubular cavity between the transducer shaft and the crater in the crankshaft. The sensing portion is fixed to a holder (10) attached to the driving source.

Description

A mechanical coupling between a driving source and a load object designed for application of transducers for torque, rotation speed or angular position or a combination thereof

Technical Field

There is generally a desire to be able to measure the torque transmitted from a driving source to a load object. In several such contexts there is also often a desire to be able to measure the speed of the driving shaft as well as the angular position of the shaft. However, pulsations in the driving torque and also the environment often obstruct these measurements. Such a problem field is the measuring of the torque transmitted from an internal-combustion engine to a load object. In connection with the measuring on vehicles of the torque transmitted from the crankshaft via the flywheel and the gear box to the. driving wheels, further problems arise. The vibrations which may occur partly due to the driving system itself, e.g. as resonance frequencies, and partly due to the propagation within the vehicle of irregula¬ rities in the ground should not disturb the measurement. Another problem is that the introduction of transducers for torque, rotation speed and angular position due to space requirements should not increase the distance between the crankshaft and the flywheel. It is also a condition that it must be possible to attach the transducer rigidly with respect to torsion and without any play.

The present invention relates to a mechanical coupling between a driving source and a load object which completely satisfies the demands that may be made on a coupling which permits measurement of torque, rotation speed or angular position in such a way as to overcome the problems referred to above and to satisfy the requirements. Background Art

Although the desire to introduce measurement of the above variables in the driving system of a vehicle has existed for many years, there are at present no coupling arrangements which totally satisfy all of the above-mentioned require¬ ments. A mechanical coupling almost satisfying the require¬ ments is described in SE 92004779 (US Application Serial No. 08/003,830). The patent describes a coupling between a driving source and a load object comprising a pipe, which at one end is covered by a plate and at the other end is equipped with a flexible flange with holes for fastening screws for the coupling to the driving source. One end of a transducer shaft is attached concentrically in the coupling and to the plate. The other end of the transducer shaft is linked via a joint to the load object. The stationary torque measuring transducer can be supported by the transducer shaft and be fixed to the driving source via a clamp. hat can be said negatively about this coupling is that it is somewhat difficult to manufacture.

However, there are a multitude of patented couplings which could manage the environmental problems, such as vibrations, etc. but which do not provide the compact design being required. Such a coupling is described in US-A-4,555, 956

'Torquemeter Apparatus'. This shows that the driven portion is directly linked to the driving portion and that the torque measuring transducer, via a sleeve equipped with grooves, is placed outside of the coupling bearing. This arrangement certainly permits the torque measuring part to be screened from axial and radial forces, but, as is clear, the design does not entail the desired compact design.

Another coupling is shown in US-A-3, 649,058 'Torque Trans- mitting Coupling". One of the peripheries of the shaft in the coupling has a camshaft profile. Two conical flanges, connectable by means of screws, surround the end portion of this shaft. At least one of the flanges has an inner opening corresponding to the shaft end with a camshaft profile. The flanges are fixed to the other shaft end of the coupling and with the minimum diameters of the flanges facing away from each other. In one embodiment one of the flanges is integra¬ ted into a cylindrical sleeve to be able to carry radial forces. This design does not constitute such a design that it would be possible to use in an application as above. Nor is it suited to be mounted in combination with a torque measuring transducer.

The flywheel of the existing designs are generally linked to the crankshaft by means of a robustly dimensioned flange coupling. ith its relatively large mass inertia, the fly¬ wheel operates dampening on the torque pulsations created in an internal-combustion engine. Normally, in manually geared vehicles, the flywheel is also integrated into the coupling between the internal-combustion engine and the gear box. In vehicles with an automatic gear box there is normally no flywheel and instead the transmission from the internal- combustion engine to the automatic gear box is provided by means of a carrier plate. The torque dampening is then provided by means of the carrier plate and the oil which is present in the automatic gear box.

However, the integration of the present transducer can be performed in the same way, irrespective of whether the vehicle is to be equipped with a manual or an automatic gear box.

To cover the alternatives with flywheel and carrier plate with and without inertia of mass, the intermediate link between the crankshaft and the gearbox will be referred to below as 'carrier' . The problem to be solved by a mechanical coupling according to the invention is thus to replace the existing flange coupling between the crankshaft and carrier with a mechanical coupling which permits a possibility of measuring transmitted torque, rotation speed or angular position, or a combination thereof, without any need to increase the distance between the internal-combustion engine and the carrier. The mechanical coupling should also prevent bending vibrations to be transmitted from the crankshaft to the carrier.

Summary of the invention and its advantages

The mechanical coupling according to the invention provides a mechanical link between the driving source crankshaft and the load object carrier. It consists of a transducer shaft which, at one end, is fixed to the carrier by means of a first joint and, at its other end, is fixed by means of a second joint into a crater concentrically hollowed out in the crankshaft. The hollowed-out crater is formed so as to provide attachment of the transducer shaft to the crankshaft on the driving source side of the crankshaft bearing located closest to the carrier. In addition, the crater is designed such that, concentrically between that portion of the crankshaft which is carried by said crankshaft bearing and the transducer shaft, a tubular cavity is formed. In this cavity the stationary sensing portion of the transducer will be fixed. Conveniently this can be achieved by attaching the sensing portion, in turn, to a holder fixed to the motor block.

Such a coupling, for the introduction of measuring devices for torque, rotation speed or angular position, or a combina¬ tion thereof, means that the existing distance between the driving source and the load object of current designs can be easily maintained. Since the attachment of the transducer shaft in the crankshaft is located very close to the crank¬ shaft bearing nearest the carrier, in addition, only very small bending vibration amplitudes will be transmitted further from the crankshaft to the carrier.

Any special design of the transducer shaft and the sensing portion for measuring quantities as above is part of the invention. The mechanical coupling itself entails no restric¬ tions regarding the choice of measuring principle.

Description of the preferred embodiments

The invention is illustrated in the accompanying figure and consists of a mechanical coupling between the shaft of a driving source and a load object, symbolically shown at 'B' . A transducer shaft 1 is attached, at one end, by means of a first joint 2 to a carrier 3 and, at the other end, by means of a second joint 4 into a concentric crater provided at the end of the driving source crankshaft 5. The crankshaft bearing nearest the carrier is shown at 6. The bearing of the rear piston rod (not shown) is shown at 7. As is clear from the summary of the invention there is a tubular cavity 8 between the transducer shaft and the crankshaft crater under the bearing 6. This cavity accommodates the measurement- sensing portion 9 which is free-standing in relation to both the inner circular-cylindrical surface of the crankshaft and the transducer shaft surface. This portion is in turn fixed to a holder 10 which can then be attached to the driving source.

The second joint 4 between the transducer shaft 1 and the crater in the crankshaft 5 may in some cases need to be reinforced with a sleeve of high-strength material welded into the crater.

There are several different partial embodiments within the scope of the invention and the embodiment described above. According to the figure the transducer shaft 1 can be designed with different diameters for the portion with clearance under the bearing 7 and the portion to be attached into the crankshaft crater, respectively.

The joints 2 and 4 fixing the transducer shaft to the carrier and the crankshaft crater, respectively, may be designed in several different ways. Examples of joints can be splines or polygon joints allowing a certain axial mobility. The joints may also consist of ordinary welded joints.

The transducer shaft may also be an integral part of the carrier, the first joint 2 then being omitted according to the above. The free end of the transducer shaft must then be adapted to the second joint 4 towards the crankshaft. The crankshaft has to be hollowed out with a sufficiently large cavity for the sensing portion and be machined for the necessary second joint 4 according to the above to be attached to the crankshaft.

In a corresponding way the transducer shaft may also be an integral part of the crankshaft, the second joint 4 then being omitted according to the above. In the crankshaft the cavity 8 for the sensing portion 9 must then be removed and the end of the transducer shaft/crankshaft must be adapted to the first joint 2 according to the above.

Claims

1. A mechanical coupling between a crankshaft (5) of a driving source and a carrier (3) of a load object, wherein the mechanical coupling comprises a transducer shaft (1) intended to be included in a measuring device for torque, rotation speed or angular position, or a combination thereof, and wherein the measuring device comprises a sensing part (9) which via a holder (10) is fixed to the driving source, characterized in that the transducer shaft at one end is attached to the carrier (3) by means of a first joint (2), the carrier consisting of a flywheel or a carrier plate, and that the transducer shaft at its other end is attached by means of a second joint (4) into a crater hollowed out in the crankshaft (5) end, the attachment being provided on the driving source side of the crankshaft bearing (6) located closest to the carrier, and that the crater is formed such that, concentrically between that portion of the hollowed-out crankshaft which is carried by said crankshaft bearing (6) and the transducer shaft, a tubular cavity (8) is formed, and that the measuring device is placed with clearance in said cavity.

2. A mechanical coupling according to claim 1, characterized in that the first joint (2) is designed as a splines or polygon joint.

3. A mechanical coupling according to claim 1, characterized in that the second joint (4) is designed as a splines or polygon joint.

4. A mechanical coupling according to claim 1, characterized in that the second joint (4) comprises a sleeve of high-strength material welded into the crater of the crankshaft.

5. A mechanical coupling according to claim 1, characterized in that the transducer shaft (1) is an inte¬ gral part of the carrier (3).

6. A mechanical coupling according to claim 1, characterized in that the transducer shaft (1) is an inte¬ gral part of the crankshaft (5) .