GB1569661A - Seal arrangement between an outdrive unit and a hull of a vessel - Google Patents

Description

(54) SEAL ARRANGEMENT BETWEEN AN OUTDRIVE UNIT AND A HULL OF A VESSEL (71) We, YANMAR DIESEL ENGINE COMPANY LIMITED, a Body Corporate organised and existing under the Jaws of Japan, of 62, Chaya-Machi, Kita-Ku, Osaka, Japan, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a seal arrangement between an outdrive unit and a hull of a vessel such as a sailing boat.

Generally, an outdrive arrangement for a sailing boat has an engine and an outdrive unit mounted on an installation bed having an opening through which an arm of the outdrive unit passes. The installation bed is adapted to be mounted on the bottom of the boat hull with the opening in the bed and an opening in the hull in register.

It is thus necessary to provide a seal between the said opening and the outdrive unit. For this purpose a sealing mechanism has been used in which tapered seats engaging each other are provided on the opening of the installation bed and an outer wall of the outdrive unit, a fixed rubber ring being arranged between boh the seats being adapted to be compressed by the weight of the outdrive unit. The above fixed rubber ring makes for a secure seal, but it requires a costly universal joint at a joint of the outdrive unit and engine due to inferior flexibility (adaptability and elasticity) in relation to the hull, thus leading to a complicated structure.An annular rubber diaphragm attached between the opening of the installation bed and the outdrive unit will improve the flexibility in relation to the hull, enable direct coupling to the engine, and simplify the structure by requiring no universal joint. However, it impairs safety in that the boat may sink in the event of the rubber diaphragm being broken, for example by driftwood.

An object of the invention is to provide an improved seal arrangement between an outdrive unit and a hull of a vessel. Accordingly the invention provides a double seal arrangement between an outdrive unit and a hull of a vessel wherein the outdrive unit is mounted on a bed in register with an aperture in the hull, the seal arrangement comprising a first outer seal formed by a resilient diaphragm extending between the periphery of said aperture and the outdrive unit, and a second inner seal formed by a flange extending inwardly from the outer periphery of said diaphragm to near to a casing of the outdrive unit, and a ring-seal between the inner periphery of the flange and said casing of the outdrive unit.

The double seal arrangement improves the safety and reliability, but there is some danger of failure to effect repair or exchange in the event of the first seal being broken because it is difficult to check whether the diaphragm is a functioning normally.

Preferably, therefore, a float switch (such as a float type electric sensor) is arranged in the space between the two seals and included in a warning circuit.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein: Fig. 1 is a partially sectional view of a rear part of a sailing boat having a seal arrangement in accordance with the present invention; Fig. 2 is an enlarged sectional view of the seal arrangement shown in Fig. 1; Fig. 3 is a partially sectional view taken on a plane normal to that of Fig. 2 and showing a warning sensor; Fig. 4 is a view illustrating the function of the sensor; and Fig. 5 shows a warning circuit diagram for the sensor.

A sailing boat has a hull 1 to a base of which is attached an installation bed or bearer 2 for an outdrive unit 4. The outdrive unit 4 is directly coupled to an engine 3, and is supported on the installation bed 2 by a three point suspension comprising two front side vibration isolating-cushions 5 and one rear vibration isolating cushions 6. The outdrive unit 4 extends through an opening 7 in the installation bed 2 and an opening 8 in the hull 1, and has a propeller 9. A double seal arrangement in accordance with the present invention is incorporated between the opening 7 and a casing of the outdrive unit 4.

The outdrive unit has an upper part 11 and a lower part 12, fastened to each other by means of a plurality of bolts (not shown).

An inner annular thicker part 14a of a rubber diaphragm seal 14 is simultaneously secured to the unit 4 by a mating surface 13 on part 11. An annular outer thicker part 14b of the seal 14 is clamped to an upper surface of the installation bed 2 by an outer peripheral part of an annular sealing flange 15 which is fastened thereto by a plurality of bolts. The clearance between the opening 7 and the outdrive unit casing is com pletély closed by the seal 14. As the rubber diaphragm seal 14 has an annular upper projection 14c integral therewith, it permits free movement of the outdrive unit casing and reduces vibration therefrom.

A central part of the flange 15 stretches upwards and inwards to cover an upper side of the diaphragm seal 14 with a clearance 10 between them, and terminates in a U-section sealing groove 16. A rubber ring seal 17 is located in the sealing groove 16 and by one edge thereof resiliently bears against a cylindrical part 18 provided on the upper part 11. A clearance 1 between the inner edge of the flange 15 and the part 18 is selected to be a little larger than the maximum radial amplitude of longitudinal and transverse movements of the upper part 11, so that there is no possibility of the cylindrical part 18 making direct contact with the flange 15 during operation.

The seal 17 always elastically contacts the sealing groove 16 and the cylindrical part 18 during operation, and has characteristics which ensure a good seal at all times. The seal is illustrated as having an inverted Ushaped section, however, it can alternatively be of hollow circular section or a- solid 0ring.

The upper unit 11 is rigidly fixed to an engine crank case by means of a SAE mounting flange 20. An input shaft 21 is directly coupled to a crank shaft 22 of an engine without using a universal joint. A bevel gear 23 is provided on the inner end of the input shaft 21. Transmission shaft part 24 carries forward and backward bevel gears 26 and 27 meshing with the bevel gear 23 and, both being in free rotation on the transmitting shaft part 24 which is con nected to a lower transmission shaft 25. A coupling sleeve 28 which is splined to the transmitting shaft 24, moves upward or downward on the transmitting shaft 24 --throgh - operation of a shifting fork (not shown) engaged with an annular groove 29, thus coupling the bevel gear 26 or 27 to the transmitting shaft 24 through a dog clutch-30 or 31.A bevel gear 33 is fixed to the bottom of the transmitting shaft 25.

A propeller shaft 34 (on tip end of which a propeller (not shown) is to be fixed) has a bevel gear 35 fixed thereto and the bevel gears 33 and 35 mesh. Further, bearings are indicated at 36, 37, 38, 39, 40 and 41 brackets 42 and 43 are for mounting vibration isolating cushions.

The bodies of the outdrive 4 and engine 3 are rigidly coupled through the moounting flange 20, and the crank shaft 22 and the input shaft 21 are also directly coupled, so that the coupled body vibrates solidly on the installation bed 2 via the vibration isolat ing cushions 5 and 6. The torque of the engine is directly transmitted from the crank shaft 22 to the input shaft 21, and from the bevel gear 23 on the input shaft tip end through the bevel gear 26 or 27 to the transmitting shafts 24 and 25, further through the bevel gears 33 and 35 and the propeller shaft 34 to the propeller 9. The clearance between the openings 7 and 8 and the outdrive unit body arranged in a central part thereof is sealed by rubber diaphragm seal 14 and the sealing flange 15 and the ring seal 17 in succession.

The sea water sealing arrangement of the installation has a first rubber diaphragm type seal and a second flexible annular seal.

Therefore, reliability and safety in a long cruise are greatly improved because sea water can well be sealed at the second seal in the event of breakage of the diaphragm seal 14. The simple direct coupling mech anism without costly universal joint permits the entire structure to be simple and cheap.

Further, the above mentioned diaphragm seal 14 and the seal ring 17 greatly improve the flexibility in relation to the hull. The inner edge of the rubber diaphragm seal 14 is secured when uniting the upper part 11 and the lower part 12. The outer edge of the seal 14 is also secured when tightening the sealing flange 15. The number of parts needed to secure reliable sealing is thus relatively small.

As a variation the ring seal 17 can be fixed to the wall of the upper part 11.

Referring now to Fig. 3, it will be seen that a cylindrical boss 15a is provided on a sealing flange 15 and a cover 45 overlies a top opening of the cylindrical boss 15a and seals via packing 46. The cover 45 is secured to the boss 15a by a plurality of bolts (not shown). An electric float switch 47 is mounted via a die thread washer 48.

A float 47b can move freely vertically in a space 10a, which is surrounded by the cylin drical boss 15a, and is guided by a carrier pin 47a. A switch 47 is set to "OFF" when sea water level is lower than a plane L, and set to "ON" when it becomes higher than plane L. A wire 49 leads to a warning circuit. To avoid the switch 47 being impeded its function by air sealed in the space 10a should sea water enter, the switch functioning plane L is preset at a low level.

Fig. 4 shows the function of the warning device upon entry of water when the lower rubber diaphragm seal is broken at 50 due to contact with driftwood or any other obstacle. The water raises float 47b the float switch 47 and the switch is turned to "ON".

Fig. 5 shows the warning circuit, which has a battery (12v) 51, and a resistance 52.

A warning lamp 53 (illuminant diode) also in the circuit is mounted on an instrument panel. The lamp 53 will light when the switch 47 is set to "ON" in this circuit.

A buzzer may be used in place of the lamp 53, or a buzzer and lamp may be used together.

The electric float switch 47 is arranged in the space 10 between the seals and the switch 47 is included in the warning circuit, so that a warning signal is given immediately in the event of breakage of the lower first seal.

Thus the safety and reliability can be high because it becomes possible to exchange the first seal before setting out on a long cruise, if not so the ship may safely go on cruising using the second seal only to the nearest port.

WHAT WE CLAIM IS: 1. A double seal arrangement between an outdrive unit and a hull of a vessel wherein the outdrive unit is mounted on a bed in register with an aperture in the hull, the seal arrangement comprising a first outer seal formed by a resilient diaphragm extending between the periphery of said aperture and the outdrive unit, and a second inner seal formed by a flange extending inwardly from the outer periphery of said diaphragm to near to a casing of the outdrive unit, and a ring-seal between the inner periphery of the flange and said casing of the outdrive unit.

2. A seal arrangement as claimed in claim 1, in which an electric float switch is arranged in a space between the two seals and is included in a warning circuit in order to give warnings should water enter the space. seal arrangement as claimed in 3. A claim 1 or 2, wherein the outer periphery of the diaphragm seal is secured to the bed by an outer edge of the sealing flange.

4. A seal arrangement as claimed in claim 1, 2 or 3, wherein the inner periphery of the diaphragm seal is clamped between upper and lower parts of the outdrive unit.

5. A seal arrangement as claimed in any preceding claim, wherein the inner edge of the sealing flange has a groove which engages the ring seal.

6. A seal arrangement as claimed in any preceding claim wherein the ring seal is of inverted U-shaped cross-section.

7. A seal arrangement as claimed in any preceding claim, wherein the outdrive unit is connected directly to an output shaft of an engine.

8. A seal arrangement as claimed in any preceding claim, wherein the diaphragm seal has an upwardly extending annular rib.

hereinbefore described with reference to 9. A seal arrangement substantially as and as illustrated in the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. drical boss 15a, and is guided by a carrier pin 47a. A switch 47 is set to "OFF" when sea water level is lower than a plane L, and set to "ON" when it becomes higher than plane L. A wire 49 leads to a warning circuit. To avoid the switch 47 being impeded its function by air sealed in the space 10a should sea water enter, the switch functioning plane L is preset at a low level. Fig. 4 shows the function of the warning device upon entry of water when the lower rubber diaphragm seal is broken at 50 due to contact with driftwood or any other obstacle. The water raises float 47b the float switch 47 and the switch is turned to "ON". Fig. 5 shows the warning circuit, which has a battery (12v) 51, and a resistance 52. A warning lamp 53 (illuminant diode) also in the circuit is mounted on an instrument panel. The lamp 53 will light when the switch 47 is set to "ON" in this circuit. A buzzer may be used in place of the lamp 53, or a buzzer and lamp may be used together. The electric float switch 47 is arranged in the space 10 between the seals and the switch 47 is included in the warning circuit, so that a warning signal is given immediately in the event of breakage of the lower first seal. Thus the safety and reliability can be high because it becomes possible to exchange the first seal before setting out on a long cruise, if not so the ship may safely go on cruising using the second seal only to the nearest port. WHAT WE CLAIM IS:

1. A double seal arrangement between an outdrive unit and a hull of a vessel wherein the outdrive unit is mounted on a bed in register with an aperture in the hull, the seal arrangement comprising a first outer seal formed by a resilient diaphragm extending between the periphery of said aperture and the outdrive unit, and a second inner seal formed by a flange extending inwardly from the outer periphery of said diaphragm to near to a casing of the outdrive unit, and a ring-seal between the inner periphery of the flange and said casing of the outdrive unit.

2. A seal arrangement as claimed in claim 1, in which an electric float switch is arranged in a space between the two seals and is included in a warning circuit in order to give warnings should water enter the space. seal arrangement as claimed in

3. A claim 1 or 2, wherein the outer periphery of the diaphragm seal is secured to the bed by an outer edge of the sealing flange.

4. A seal arrangement as claimed in claim 1, 2 or 3, wherein the inner periphery of the diaphragm seal is clamped between upper and lower parts of the outdrive unit.

5. A seal arrangement as claimed in any preceding claim, wherein the inner edge of the sealing flange has a groove which engages the ring seal.

6. A seal arrangement as claimed in any preceding claim wherein the ring seal is of inverted U-shaped cross-section.

7. A seal arrangement as claimed in any preceding claim, wherein the outdrive unit is connected directly to an output shaft of an engine.

8. A seal arrangement as claimed in any preceding claim, wherein the diaphragm seal has an upwardly extending annular rib.

hereinbefore described with reference to

9. A seal arrangement substantially as and as illustrated in the accompanying drawings.