Torsional Force Transmitting Apparatus

Abstract

The present invention aims to couple a propeller with a power output shaft to transmit the torsional force of the power output shaft to the propeller. The apparatus includes a first sleeve and a second sleeve that form a coupling surface between them to hold a torsional force transfer means. The torsional force transfer means is coupled with the first sleeve and the second sleeve to transmit only a selected amount of the torsional force. The first sleeve has a first outer surface and the second sleeve has a second inner surface that are engaged respectively with the propeller and the power output shaft in the rotating direction so that the power output shaft can transmit the torsional force to the propeller. In the event that the propeller is overloaded the torsional force transfer means between the first sleeve and the second sleeve slip to form a protection mechanism.

Description

FIELD OF THE INVENTION

The present invention relates to a torsional force transmitting mechanism and particularly to a torsional force transmitting apparatus for propellers to provide overload protection.

BACKGROUND OF THE INVENTION

A torsional force transmitting apparatus aims to couple a propeller with a power output shaft. When a boat sails the propeller might hit unknown objects such as reefs. Such an incident could generate an excessive load torsional force and result in breaking or damage of the propeller, engine and gear box. To protect the propeller, engine and gear box, the torsional force transmitting apparatus ought to be slipping or broken. By replacing the torsional force transmitting apparatus with a new one the boat can sail again. Such an approach can save repair cost and time.

However, the conventional torsional force transmitting apparatus used on a propeller is formed by squeezing a round rubber into a round inner hole of the propeller through a press. By controlling the compressed amount of the rubber a positive force to the round inner hole of the propeller is provided. And by controlling the amount of the positive force the amount of torsional force that can be transmitted by the rotating propeller can be determined. In the event of overloading, and slipping or breaking occurs, a protection mechanism is formed. But such an approach has to rely on the press to perform replacement and repairs when damage occurs. And the replacement and repairs have to be done at a professional repair shop. Moreover, the positive force provided by the rubber highly depends on temperature. Used on a high horsepower engine, the temperature rises easily and the rubber becomes soft and results in slipping. At a lower temperature the rubber becomes harder, the protection effect diminishes.

U.S. Pat. No. 4,566,855 discloses another torsional force transmission apparatus for propellers. It has a rubber-made resilient shock mount sleeve with the outer perimeter formed in a gear shape to mate an inner hole of a propeller and an inner hole formed in another gear shape to mate the outer perimeter of a spline driver sleeve adaptor. By controlling the depth of the gear, a positive force is generated by deformation of the rubber when the resilient shock mount sleeve rotates that is used to transmit the torsional force. Namely the depth of the gear can determine the amount of a load torsional force, thereby control the transmitting torsional force to produce slipping. Such a technique does not do installation by compaction, hence does not require a press to do replacement when damage occurs. Users can do repairs by themselves if desired. But due to the rubber is installed without being compressed in advance, and only the teeth of the gear are compressed during rotation, the compressed amount is little. Hence the transmitting torsional force also is limited. It is not suitable for a high power engine system.

U.S. Pat. No. 5,322,416 discloses yet another technique which has the resilient shock mount sleeve made from plastics. The outer perimeter of the resilient shock mount sleeve and the inner hole of the propeller are formed respectively in an octagonal shape. The resilient shock mount sleeve has an inner hole and the drive sleeve has an outer perimeter that are formed respectively in a gear shape. The resilient shock mount sleeve generates a positive force resulting from deformation during rotation to transmit the torsional force. It also is not installed by compaction and can be repaired by the users. As the material is switched to plastics, a smaller compression amount can transmit a greater torsional force. Hence it can be used on a higher power engine system. In the event that impact of an external force occurs that exceeds the torsional load, the plastics fracture to provide a protection mechanism. But the plastics still highly depend on temperature. Use in an environment of a lower temperature, it is hardened and might not break even under the impact of an estimated breakable torsional force. As a result, damages of the propeller, engine and gear box could occur. Moreover, when the rotational direction of the propeller is switched the contact surface of the resilient shock mount sleeve and the propeller also changes. During switching a great deal of noise and shock are generated due to no buffer is provided.

SUMMARY OF THE INVENTION

Therefore the primary object of the present invention is to provide a torsional force transmitting apparatus that is not easily affected by temperature and generates less noise and shock.

The torsional force transmitting apparatus of the invention aims to be used on propellers to couple a propeller with a power output shaft to transmit the torsional force of the power output shaft to the propeller. It includes a first sleeve, a second sleeve and a torsional force transfer means. The first sleeve has a first inner surface which is coupled with a second outer surface of the second sleeve in a rotary manner to form a coupling surface. The torsional force transfer means is located on the coupling surface. The torsional force transfer means connects the first sleeve and the second sleeve, and can transmit only a selected amount of the torsional force. The first sleeve has a first outer surface and the second sleeve has a second inner surface that are engaged respectively with the propeller and the power output shaft in the rotating direction.

By means of the construction set forth above, the selected amount of torsional force transmittable can be controlled through the torsional force transfer means. When the torsional force of the power output shaft is transmitted to the propeller, and the propeller hits a unknown object and results in significant increase of the torsional force and overloaded, the torsional force transfer means between the first sleeve and the second sleeve breaks and loosens, hence the first sleeve and the second sleeve rotate idly to provide protection for the propeller, engine and gear box.

The foregoing, as well as additional objects, features and advantages of the invention will be more readily apparent from the following detailed description, which proceeds with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the invention.

FIG. 2 is a cross section of the invention in a use condition.

FIG. 3 is an exploded view of another embodiment of the invention.

FIG. 4 is a fragmentary cross section of yet another embodiment of the invention.

FIG. 5 is a fragmentary cross section of still another embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Please refer to FIGS. 1 and 2, the torsional force transmitting apparatus according to the invention aims to transmit the torsional force of a power output shaft 10 to a propeller 20. It includes a first sleeve 30A, a second sleeve 40A and a torsional force transfer means 50A. The first sleeve 30A has a first inner surface 31 and a first outer surface 32 which is non-circular. The propeller 20 also is formed in a non-circular profile such that the second outer surface 32 can be engaged with the propeller 20 in the rotating direction.

The second sleeve 40A has a second inner surface 41 and a second outer surface 42. The second inner surface 41 has annular inner teeth 43 formed thereon. The power output shaft 10 has annular outer teeth 11 mating the annular inner teeth 43 so that they can be coupled and installed together with the second inner surface 41 engaging with on the power output shaft 10 in the rotational direction. The power output shaft 10, through the mutual engagement of the annular inner teeth 43 and the annular outer teeth 11, can transmit the torsional force to the second sleeve 40A.

The first inner surface 31 of the first sleeve 30A and the second outer surface 42 of the second sleeve 40A are coupled together in a rotary manner to form a coupling surface 35. The torsional force transfer means 50A is located on the coupling surface 35 by disposing an adhesive 36 onto the coupling surface 35. By changing the type and size of the bonding surface of the adhesive 36 the amount of the torsional force transmittable can be controlled. Hence the torsional force transfer means 50A which couples the first sleeve 30A and the second sleeve 40A can transmit only a selected amount of the torsional force.

By means of the construction set forth above, when the power output shaft 10 is engaged with the propeller 20, and the propeller 20 hits an unknown object and results in great increase of the torsional force and overloaded, the torsional force transfer means 50A breaks down so that the first sleeve 30A and the second sleeve 40A rotate idly. As a result breaking of the propeller 20 can be prevented. And the engine and gear box also are protected.

Refer to FIG. 3 for another embodiment of the invention. It has a torsional force transfer means 50B located on the coupling surface 35 between the first inner surface 31 of a first sleeve 30B and the second outer surface 42 of a second sleeve 40B. The coupling surface 35 has at least one flute 44 formed thereon to hold an elastic element 45. The flute 44 is evenly spaced on the coupling surface 35. The elastic element 45 includes a rubber strut 451 coupling with a spring 452. The second sleeve 40B has two ends holding respectively a first pad 46 and a second pad 47. The first sleeve 30B runs through the second sleeve 40B. After the elastic element 45 is wedged in the flute 44, the upper pad 46 and the lower pad 47 are bonded to the first sleeve 30B, thereby to prevent the first sleeve 30B and the second sleeve 40B from sliding against each other and anchor the elastic element 45. In the event that the torsional force between the first sleeve 30B and the second sleeve 40B is excessive, the elastic element 45 is compressed and deforms, and an idle rotation occurs between the first sleeve 30B and the second sleeve 40B. By changing the number of the flute 44, the torsional force transmittable can be controlled. The upper pad 46 and the lower pad 47 may be made from rubber. The upper pad 46 and the lower pad 47 are formed at a dimension slightly larger than the inner diameter of the propeller 20. Hence when the first sleeve 30B is engaged with the propeller 20 through the upper pad 46 and the lower pad 47 in the rotational direction a shock absorbing effect can be achieved to reduce noise and vibration during rotation of the propeller 20.

Refer to FIG. 4 for yet another embodiment of the invention. The second outer surface 32 of a first sleeve 30C is encased by an elastic material 60 which may be rubber or plastics. The first sleeve 30C and the propeller 20 are engaged through the elastic material 60. Such a structure also can absorb shock to reduce noise and shock during rotation of the propeller 20.

Refer to FIG. 5 for still another embodiment of the invention. The second outer surface 32 of a first sleeve 30D has a plurality of ribs 321. The inner hole of the propeller 20 has a corresponding shape. Moreover, there are a plurality of elastic struts 70 on one side of the ribs 321 to be interposed between the propeller 20 and the first sleeve 30D. The first sleeve 30D is in contact with the propeller 20 through the elastic struts 70. Therefore a shock absorbing effect can be achieved to reduce noise and shock during rotation of the propeller 20.

As a conclusion, the present invention provides torsional force transfer means 50A and 50B between the first sleeves 30A and 30B and second sleeves 40A and 40B. The torsional force transfer means 50A and 50B can transmit only a selected amount of torsional force, thus form a protection mechanism. Thereby it can protect the more expensive propeller 20 or the engine and gear box coupling with the power output shaft 10. By selecting varying types and bonding sizes of the adhesive 36 or changing the number of the flute 44, the transmittable torsional force can be controlled to suit different types of propeller 20. In the event of damage, due to the first sleeves 30A and 30B, the second sleeves 40A and 40B, and the propeller 20 are not engaged by compaction in the axial direction, replacement can be done easily to meet user's requirements.

Claims

1. A torsional force transmitting apparatus to transmit a torsional force of a power output shaft to a propeller, comprising:

a first sleeve which has a first inner surface and a first outer surface which is engaged with the propeller in a rotational direction;

a second sleeve which has a second inner surface and a second outer surface, the second inner surface being engaged with the power output shaft in the rotational direction, the first inner surface and the second outer surface being coupled together in a rotary manner to form a coupling surface; and

a torsional force transfer means located on the coupling surface to couple the first sleeve and the second sleeve and transmit only a selected amount of the torsional force.

2. The torsional force transmitting apparatus of claim 1, wherein the torsional force transfer means is formed by disposing an adhesive on the coupling surface; the amount of the torsional force transmittable being controlled by changing the type and bonding size of the adhesive.

3. The torsional force transmitting apparatus of claim 1, wherein the torsional force transfer means is formed by carving at least one flute on the coupling surface between the first inner surface and the second outer surface to allow an elastic element to be wedged in, the second sleeve having two ends to hold respectively a upper pad and a lower pad that are bonded to the first sleeve to prevent the first sleeve and the second sleeve from sliding against each other to anchor the elastic element, the amount of the torsional force transmittable being controlled by changing the number of the flute.

4. The torsional force transmitting apparatus of claim 3, wherein the elastic element includes a rubber strut coupling with a spring.

5. The torsional force transmitting apparatus of claim 3, wherein the upper pad and the lower pad are made from rubber, and formed at a dimension slightly larger than an inner diameter of the propeller.

6. The torsional force transmitting apparatus of claim 1, wherein the first outer surface of the first sleeve is encased by an elastic material.

7. The torsional force transmitting apparatus of claim 6, wherein the elastic material is rubber.

8. The torsional transmission apparatus of claim 6, wherein the elastic material is plastics.

9. The torsional force transmitting apparatus of claim 1, wherein the first outer surface is non-circular and the propeller has a corresponding non-circular profile.

10. The torsional force transmitting apparatus of claim 1, wherein the second inner surface has annular inner teeth and the power output shaft has annular outer teeth corresponding to the annular inner teeth to be coupled together for installation such that the annular inner teeth and the annular outer teeth are engaged to allow the power output shaft to transmit the torsional force to the second sleeve.

11. The torsional force transmitting apparatus of claim 1, wherein the first outer surface has a plurality of ribs and the propeller has an inner hole formed in a shape corresponding to the first outer surface, the propeller and the first sleeve being interposed by a plurality of elastic struts on one side of the ribs.