This invention relates to an underwater vehicle which is remotely controlled from a boat or other above water location and wherein control signals are provided to the vehicle by an umbilical cable. Remotely controlled underwater vehicles are widely used for pleasure, research and commercial purposes and in particular are commonly equipped with a photographic or video camera for the purpose of recording the underwater scene and/or direct viewing of the scene. It is common to propel such vehicles by electric motors which drive propellers or other devices for generating thrust to propel the vehicle and to effect the steering thereof.

It is the object of the present invention to provide an underwater self-propelled vehicles of a construction that provides improved reliability in operation, convenient, and simplified control in operation, and improved stability.

With this object in view there is provided a remotely controlled underwater self-propelled vehicle having propulsion and manoeuvering means driven by respective electric motors,said vehicle having a sealed main body and a cable extending from the main body to transmit electric energy and control signals from a remote source to the interior of the main body, control means within the main body operable in response to control signals received through said cable to selectively supply electrical energy received through said cable to said electric motors, each said electric motor being mounted in a respective motor housing demountably attached to the main body to provide, when so attached, a sealed enclosure for the motor, respective interconnecting cable means passing in sealed relation from the main body into each housing and connected to the respective electric motor therein. Conveniently the electric motors are connected to respective propellers by shafts extending through the motor

housing with appropriate seals between the shafts and the motor housing.

The provision of the electric motors in housings which are themselves sealed from the interior of the main body of the vehicle, provides additional security in the event of a leak developing between the shafts driving the propellers and the motor housings. Water entering any one of the motor housings as a result of such a leak will not enter the interior of the main body where electrical and electronic control gear is housed. This construction therefore substantially reduces the extent of potential damage to the internal mechanisms of the vehicle, and as a consequence makes servicing, in the event of motor failure, relatively simple, without disturbing the sealed condition of the main body of the vehicle. Conveniently there is provided an access opening in the main body at a location

-v ^" * ^* .at is enclosed by one of the motor housings when that housing is in assembly with the main body. A detachable partition is provided to normally sealably close the access opening. The partition interposed between the main body and the motor housing.

In accordance with a further aspect, the present invention provides an underwater self-propelled vehicle having respective thrust means to propel the vehicle in horizontal and vertical directions respectively and ballast means rigidly attached to the vehicle so the vehicle has substantially zero or slight positive bouyancy, said ballast means being arranged so the centre of gravity of the vehicle is below the centre of bouyancy. Conveniently the ballast means is arranged so the weight of the ballast means is distributed to locate th.e centre of gravity substantially on th line of thrust of the vertical direction thrust means

Preferably the thrust means to propel the vehicLe in the vertical direction is a single thrust device such as a motor driven propeller, with the axis of rotation of the propeller vertical and passing substantially through the centre of gravity of the ballasted vehicle.

Conveniently a lateral thrust means is provided to be used to steer the vehicle in the generally horizontal direction. This lateral thrust means may also be operated to counteract the torque raction of the vertical thrust propeller to maintain stability of the vehicle.

The arrangement of the ballast as above described enables a single thrust means to be provided to effect movement in the vertical direction, with the line of the direction of thrust passing approximately through the centre of gravity so that the single thrust means is sufficient to effect the vertical movement and yet enable the vehicle to be maintained in a stable condition.

In prior underwater self-propelled vehicles it has been common practice to provide two or more thrust means to effect movement of the vehicle in the vertical direction, with these thrust means displaced to either side of the vertical plane through the centre of gravity of the vehicle in order to obtain the required stability. The provision of two thrust devices to provide vertical movement was complex and costly. There is also the further disadvantage that if, for any reason, one of the thrust means experienced a significant departure from its normal output, the stability of the vehicle would be severely disrupted.

The invention will be more readily understood from the following description of one practical arrangement of the underwater self-propelled vehicle, as illustrated in the accompanying drawings.

In the drawings,

Figure 1 is a perspective view of the self-propelled vehicle;

Figure 2 is a side elevation partly in section of the self-propelled underwater vehicle, with one of the support bows removed;

Figure 3 is a front elevation view of the self-propelled vehicle.

Referring now to the drawings, the vehicle comprises a main body 10 of an approximate elliptical toroid shape with a pair of support bows 11 attached thereto with one bow on either of the two opposite longitudinal sides of the main body 10. The bows 11 provide a convenient stand for the vehicle when it is not in the water.

A transparent vertically elongated window 12 is provided on the front of the body 10 and a conventional movie camera or video camera is mounted within the housing 10 with the lens 13, as seen in Figure 1, adjacent the inside of the window 12. The camera is mounted within the body 10 in a known manner so that it may pivot about a transverse horizontal axis so the lens 13 may pan up and down from the central position shown. In an alternative construction the window may be of a circular form, preferably outwardly dished, this window being particularly suitable for use with a camera that is mounted to pan in t ch the vertical and horizontal directions.

The main body 10 is provided with a suspension lug ^* 14 located centrally of the top of the body 10. A suitable line may be attached to the lug 14 so that the vehicle may be tethered to a boat or other above surface structure. The line may also be used for raising the vehicle in the event of a motor failure or as an assistance to the motor which. propels the vehicle in the vertical direction. Also the line is convenient for lifting the vehicle out of the water onto a deck or other support.

As seen in Figure 1, the cable 18, which incorporates electrical power conductors and signal conductors, passes through the gland assembly 19 in the'wall of the main body 10, that provides a seal therebetween. The cable 18 has sufficient tensile strength to function as a tether and lifting line and sc h et l sheath 27 ^" fitted about the cable 18 a suitable distance up fron the gland 19 may be coupled to the lug 14 as shown in Figure 1.

Located centrally of the underside of the main body 10 is a housing 15 in which is located the motor 16, as seen in Figure 2, which drives the propeller 17. The axis of the motor 16 and propeller 17 is vertical, and aligned generally with the centre of gravity 28 of the vehicle. Accordingly, in operation the propeller 17 will apply a thrust to the vehicle in the vertical direction along a line passing approximately through the centre of gravity. The motor 16 is reversible so that the propeller may either move the vehicle vertically upward or downward.

At the rear of the main body 10 is a further housing 20 in which is located the electric motor 21 coupled to a propeller 22. The rotation of the propeller 22 will apply a thrust in a horizontal direction to the vehicle. The motor 21 also being reversible so that the propeller may be driven in either direction. The line of thrust of the propellor 22 is approximately along the longitudinal axis of the main body 10.

Below the forward end of the main body 10, and integral with the lower housing 15, is a composite housing

25 including a lamp portion 26 and a steering motor portion

27. The composite housing 25 is attached to the housing 15 by the web section 28. In the motor housing portion 27 is an electric motor (not shown) similar to the motors 16 and 21 coupled to the propeller 29 which on an axis transverse to the longitudinal direction of the main body 10. The motor that drives the propeller 29 is reversible so that operation thereof can drive the propeller 29 in either direction so as to steer the vehicle to aim the camera in the required direction. It may also be necessary to operate the propeller 29 at a slow speed to counter the torque reaction of the vertical lift motor 16 whedriving the propeller 17. In use the -.- -;■.?t'jL will operate in combination the motor 16 and the motor driving the propeller 29.

The light portion 26 of the housing 25 carries an electric globe 30 and suitable reflector (not shown), with the transparent window 31 secured in position by the detachable ring 32. The portion 26 is detachable from the remainder of the housing 25 to provide access for fitting and removal of the motor that drives the propellor 29. * The main body 10 is provided with two access openings 35 and 36 through which the electrical and electronic control equipment, indicated diagramatically at 37, is installed and adjusted as required. The access openings 35 and 36 are closed by respective partition member 38 and 39. Respective '0' ring type seals 40 are provided between the partition members and the main body and clamped therebetween to form a seal by the series of screws 41. The housings 15 and 20 are clamped to the partition members 38 and 39, respectively, by a series of screws 42 with a respective '0' ring type seal 43 therebetween. This construction enables either housing 15 and 20 to be removed independently of the respective partition members so that themain body 10 remains sealed to protect the electrical and electronic controls therein.

Each of the partition members 38 and 39 is provided with a single aperture through which respective cables 24 pass with a sealing gland 35 therebetween. There is thus provided electrical communication electrical and electronic controls 37 in the body 10 and the respective electric motors 16 and 21, without loss of the effective seal between the interior of the body 10 and the interior of the respective housings. A further cable (not shown) passes through a drilled hole in the web 28, to provide the electrical energy to the light and moor incorporated in the housing 25. If desired a further seeling gland may ^* be provided between the drilled i-υi - id the cable passing therethrough.

A further cable (not shown) passes from the interior of the housing 15 into the composite housing 25 through an aperture sealed by a grommet to thereby provide electrical energy to the motor driving the propeller 29 and to the globe 30.

Between the bows 11 there is supported a ballast mass 45 of irregular annular form having a central opening 46 co-axial with the propellor 16. The ballast mass 45 is secured to the spaced cross bars 47 which in turn are secured at their ends to the bows 11. The shape positioning of the ballast mass 45 is arranged so that the centre of gravity 28 of the complete vehicle is below the level of the centre of bouyancy 48 of the vehicle, and so that each is located on or close to the line of thrust 49 of the propellor 17 as indicated in Figure 2.

This arrangement contributes to the ease of manoeuvering the vehicle and the stability thereof when both hovering and moving n the water.

The actual weight of the ballast mass is also selected so that the vehicle has close to zero bouyancy preferably a slight positive bouyancy. This reduces the extent of use of the vertical thrust of the propellor 17 required to control the depth of operation of the vehicle. The slightly posiive bouyancy is a safety feature to ensure the vehicle will rise to the surface in the event of failure of the vertical thrust motor 16.