Abstract:
A wheel assembly  10  for a golf trolley ( 30 ) comprises a wheel  12 , a motor for driving the wheel, a battery  20  for powering the motor, detection means for detecting whether or not the wheel  12  is rotating, a control unit  22  for controlling the motor and releasable connection means  24  for releasably connecting the wheel assembly  10  to a golf trolley ( 30 ), the control unit  22  having at least a first mode of operation in which the motor can be activated only when the wheel  12  is already rotating.

Description:
BACKGROUND TO THE INVENTION 
       [0001]    The present invention relates to a wheel assembly for a golf trolley. 
         [0002]    Golf trolleys which can be pushed manually around a golf course are typically of a three-wheeled design, with a pair of rear wheels and a single front wheel. A base support frame is provided between the front and rear wheels, and an upright support frame extends upwardly from a point near the rear of the base support frame. A golf bag is typically rested on the front of the frame and leans rearwardly, over the rear wheels, the top of the golf bag being supported on the upright support frame. A handle extends upwardly and rearwardly from the upright support frame and the golf trolley is pushed from the rear by the handle. 
         [0003]    Three-wheeled manual golf trolleys as described above may be foldable and may be stored compactly. However, many golf players find it difficult to push a golf bag on a trolley around a long and/or hilly course manually, and prefer a powered device. 
         [0004]    Powered golf trolleys are known, and are typically driven by an electric motor powered by a rechargeable battery. However, the batteries must be large, heavy and expensive in order to provide enough stored energy to power a golf trolley around a golf course. This results in a golf trolley which is large and unwieldy, and will not fold up as compactly as a manual trolley. The large battery also takes some time to charge. 
         [0005]    Since the useful lifespan of a battery is limited to a number of charging cycles, powered golf trolleys have a significant ongoing cost of ownership as well as being expensive to purchase in the first place. 
         [0006]    A powered golf trolley typically has driven rear wheels. This requires either an axle between the two rear wheels, or a motor on each of the two rear wheels. An axle between the two rear wheels makes for a trolley which will not fold compactly, and a requirement for two motors increases the purchase cost of the trolley. Driving only one of the rear wheels makes the trolley difficult to steer. 
         [0007]    A driven front wheel is an alternative, solving the problems with rear wheel drive mentioned above. However, the centre of mass of the loaded golf trolley is typically some way rearward of the front wheels, and a driven front wheel will therefore tend to spin due to insufficient traction with the ground. 
         [0008]    It is an object of the invention to reduce or substantially obviate the above mentioned problems. 
       STATEMENT OF INVENTION 
       [0009]    According to a first aspect of the present invention, there is provided a wheel assembly for a golf trolley comprising a wheel, a motor for driving the wheel, and a battery for powering the motor;
       detection means for detecting whether or not the wheel is rotating, and a control unit for controlling the motor, the control unit having at least a first mode of operation in which the motor can be activated only when the wheel is already rotating;   a user input means for positioning on a handle of the golf trolley, the user input means being wirelessly connected to the control unit;   and releasable connection means for releasably connecting the wheel assembly to a golf trolley.       
 
         [0013]    The wheel assembly when attached to a golf trolley provides for a ‘power assisted’ vehicle. Because the motor can be activated only when the wheel is already rotating, the power required by the motor will be small compared with the power which would be required to move the golf trolley from a standing start. This in turn means that the battery can be small, lightweight and inexpensive when compared with the batteries which are required for fully powered golf trolleys. 
         [0014]    A golf trolley with the wheel assembly attached is lightweight and easy to handle. The golf trolley is power-assisted which improves the ease with which it can be pushed around a golf course. The battery can be charged quickly and the trolley may be folded for storage. 
         [0015]    It will be understood that the control unit may have further modes of operation. For example, a second mode of operation may be provided in which the motor is activated whenever a button is pressed by a user. However, this second mode of operation will swiftly result in depletion of the battery due to the high power required by the motor to accelerate the vehicle from a standstill. It is therefore preferred to provide a control unit which operates only in accordance with the first mode of operation described above. Nevertheless, even with a flat battery, because of the lightweight nature of the wheel assembly, the golf trolley can be pushed with relative ease, unlike existing powered golf trolleys with a flat battery. 
         [0016]    The control unit in the first mode of operation may automatically activate the motor when the detection means detects that the wheel is rotating. 
         [0017]    Automatic activation provides for an effortless user experience. Pushing the trolley is easy because power assistance is automatically provided once the trolley is being pushed. 
         [0018]    The control unit in the first mode of operation may automatically activate the motor when the detection means detects that the wheel is rotating faster than a predetermined speed. This further serves to preserve battery life, by ensuring that the motor is not activated in order to accelerate the golf trolley. Rather, the motor helps to maintain the trolley at a constant speed, assisted by the manual effort of the user. The predetermined speed may be 2 mph (0.89 m/s). 
         [0019]    The control unit in the first mode of operation may activate the motor only when the detection means detects that the wheel is rotating and the user input means is activated. The user input means may be a pushbutton. 
         [0020]    Providing a pushbutton or other input means allows the user to decide when he wishes to activate the power assistance on his golf trolley. For example, the trolley may be pushed manually on flat parts of the golf course, or for the first part of a round of golf. When the user becomes tired towards the end of the game, or when he is pushing the trolley up hills, power assistance may be desired and may be activated. Nevertheless, the control unit will only activate the motor when requested to do so by the user input means and when the wheel is already rotating. The battery life is thus conserved, because the motor is not powered when the golf trolley is accelerating from a standstill, and the motor is also not powered when the user is content to push the trolley himself. 
         [0021]    Wireless communication of the pushbutton with the control unit for the motor is advantageous, since it allows the wheel assembly to be easily retro-fitted to a golf trolley, the wireless user input means being simply attached to a handle of the trolley, without any wiring being required. Even where the wheel assembly is sold together with the trolley as one product, it is advantageous to be able to remove the wheel assembly from the trolley so that the battery can be charged, perhaps indoors, whilst the bulk of the golf trolley is stored, possibly in a shed where an electricity supply may not be available. Providing wireless user input means as well as releasable attachment means facilitates removal of the wheel assembly from the golf trolley, since there are no wires to disconnect. This also allows the pushbutton to be attached anywhere the user desires on the handle of the golf trolley for comfortable operation. 
         [0022]    Wireless user input means provide the further advantage that there are no wires running along the frame of the golf trolley which might become caught in trees, hedges and the like, or become fatigued due to repetitive folding of the golf trolley. 
         [0023]    The battery may be disposed within the wheel. Providing the battery within the wheel puts the mass of the battery in the same vertical line as the driven wheel, when the golf trolley is in use. This increases the traction between the wheel and the ground, reducing the possibility that the driven wheel will spin. 
         [0024]    Alternatively, the battery may be provided in a housing next to the wheel, substantially directly behind the wheel. Again, this puts the wheel substantially in line with the driven wheel and the weight passes substantially through the wheel. In a further alternative, the battery may be housed in the forks mounting the front wheel. 
         [0025]    In this way, the battery is balanced across the wheel, and the centre of gravity of the battery may still pass through the wheel. 
         [0026]    The releasable connection means may include a connecting member for introduction into a socket on the golf trolley. The connecting member may include a recess for engaging with a locking device on the socket of the golf trolley. A releasable connection means as described is quick and easy to connect and remove, but provides for secure attachment of the wheel assembly to the golf trolley. The locking device may include a large handle for locking and unlocking. A large handle is advantageous, since it can easily be operated by a user whose fingers have become cold after a long period outdoors. 
         [0027]    In use, the wheel may be substantially in front of the connecting member and socket, so that the golf trolley is pushed in a direction substantially in-line with the connecting member and socket. 
         [0028]    According to a second aspect of the invention, there is provided a golf trolley comprising a frame mounting two rear wheels, a front wheel, and a handle;
       a motor for driving the front wheel, a battery for powering the motor, detection means for detecting whether or not the front wheel is rotating, and a control unit for controlling the motor;   the control unit having at least a first mode of operation in which the motor can be activated only when the front wheel is already rotating,   a user input means positioned on a handle of the golf trolley, and the user input means being wirelessly connected to the control unit.       
 
         [0032]    Advantageously, the front wheel is the driven wheel. The rear wheels may be unpowered. This means that an axle is not required between the rear wheels, resulting in a golf trolley which is easily foldable into a compact unit for storage or carriage. As with the wheel assembly described above, the control unit prevents power from being supplied to the motor until manual effort has been applied to the golf trolley to initially accelerate it from a standstill. As well as ensuring a useful battery life from a small battery, this overcomes the problem that a driven front wheel will tend to spin due to an inadequate downward force provided by the mass of the golf trolley. 
         [0033]    Because the wheel is only powered when it is already moving, power will only be applied when the trolley is being pushed from behind. The forward force applied by the user pushing the trolley forwards will transmit through the frame of the golf trolley, tending to pivot the golf trolley forward on the rear wheels, and this pushing the front wheel into the ground, ensuring that the front wheel finds traction. In this way, a power assisted golf trolley is made to work effectively with a powered front wheel. 
         [0034]    The control unit in the first mode of operation may automatically activate the motor when the detection means detects that the front wheel is rotating. The control unit in the first mode of operation may automatically activate the motor when the detection means detects that the front wheel is rotating faster than a predetermined speed. The predetermined speed may be 2 mph (0.89 m/s). 
         [0035]    The control unit in the first mode of operation may activate the motor only when the detection means detects that the front wheel is rotating and the user input means is activated. The user input means may be a pushbutton. The pushbutton may be mounted in any convenient location on the handle of the golf trolley. 
         [0036]    The battery may be disposed substantially in-line vertically with the front wheel. The battery may be disposed within the front wheel. The battery may be disposed in forks on either side of the wheel. The forks may mount the wheel. 
         [0037]    The front wheel may be part of a front wheel assembly which includes at least the front wheel, the motor, and the battery, the front wheel assembly being detachable from the golf trolley. 
         [0038]    The frame may include a base support frame provided between the front and rear wheels and an upright support frame extending from the rear of the base support frame. The base support frame and the upright support frame may be provided with means for supporting a bag of golf clubs. The frame may be foldable. 
         [0039]    Where the battery is disposed substantially in-line vertically with the front wheel, the mass of the battery serves to push the front wheel downwardly towards the ground. This further reduces the possibility that the front wheel will spin when it is powered. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0040]    For a better understanding of the present invention, and to show more clearly how it may be carried into effect, reference will now be made by way of example only to the accompanying drawings, in which: 
           [0041]      FIG. 1  shows a perspective view of a wheel assembly in accordance with the first aspect of the invention; and 
           [0042]      FIG. 2  shows a perspective view of a golf trolley in accordance with the second aspect of the invention. 
       
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
       [0043]    Referring firstly to  FIG. 1 , a wheel assembly for a golf trolley is indicated generally at  10 . The wheel assembly includes a wheel  12  and a wheel mounting  14 . 
         [0044]    The wheel mounting  14  includes a pair of planar side members  16 , extending from a housing  18 . The wheel  12  is mounted on a bearing between the two side members  16 , and the housing passes over and around the wheel  12 . A battery  20  and a control unit  22  are disposed within the housing  18 , and a motor is provided to drive the wheel  12 . The battery  12  may be a Lithium-Ion battery, which provides an excellent power to weight ratio. It is found that a Lithium-Ion battery weighing around 300 g is suitable to provide enough power for power assistance around a typical 18-hole golf course. 
         [0045]    A connecting member  24  extends from the rear of the wheel mounting  14 , and is in the form of a box section. The connecting member  24  includes a recess  26  in one surface, for receiving a bolt of a locking device. 
         [0046]    The control unit  22  includes wireless receiving means for receiving a signal from a wireless pushbutton control  28 , with wireless communication indicated at  29 . In use, the control unit will activate the motor to drive the wheel  12  only when a signal is received from the wireless pushbutton control  28  and when the control unit  22  detects that the wheel is already rotating at a speed of at least 2 mph (0.89 m/s). 
         [0047]    The speed of rotation of the wheel may be detected by Hall-effect sensors in the motor. Alternatively, any other suitable detection means may be used. 
         [0048]    Referring now to  FIG. 2 , a golf trolley is indicated generally at  30 . The golf trolley incorporates the wheel assembly  10  as a front wheel. The golf trolley  30  further includes a pair of rear wheels  32 , a base support frame  34  connecting the front and rear wheels, and an upright support frame  36  having a handle  38 . 
         [0049]    A lower jaw  40  is provided on the front of the base support frame  34 , and an upper jaw  42  is provided on the upright support frame  36 . In use, the base of a golf bag  100  may be introduced into and grasped within the lower jaw  40 . The golf bag may then be rested against the upright support frame  36  and held within the upper jaw  42 . 
         [0050]    A socket is provided at the front of the base support frame  34 , for accepting the connecting member  24  of the wheel assembly  10 . The socket includes a locking mechanism having a handle and a cam. The handle is movable in-line with the socket, in the direction in which the connecting member is introduced and removed. Moving the handle operates the cam which acts against a pin, which locates in the recess  26 , moving it between a locked position and an unlocked position. The cam, when in the locked position, holds the pin in the recess and the connecting member in the socket. In the unlocked position, the pin comes out of the recess, allowing unobstructed movement of the connecting member  24  within the socket. 
         [0051]    The above-described locking arrangement is easy to operate, especially where a large handle is provided. A simple push or pull is enough to release or engage the locking mechanism. This is advantageous, since users attempting to operate the locking mechanism will often have cold hands following a long round of golf. 
         [0052]    In use, the wheel assembly  10  is connected to the base support frame  34 , creating a three-wheeled golf trolley  30 . The golf trolley is intended to be pushed forwards from the handle  38 , as indicated by arrow A. As well as propelling the golf trolley forwards, the force is transmitted through the frame of the trolley, pivoting the trolley clockwise as shown in  FIG. 2  about the rear wheels  32 . This results in the front wheel being pushed downwardly, into the ground, as indicated by arrow B, improving the traction of the trolley. 
         [0053]    The wireless pushbutton remote control  44  is mounted to the handle  38  of the trolley. When the user requires power-assistance, the button  44  is pushed. The control unit  22  will power the motor to drive the wheel  12  only when the button  44  is being pushed and when the wheel  12  is already rotating at a speed of greater than 2 mph (0.89 m/s) in a forward direction, i.e. in the direction of arrow A. 
         [0054]    The power assisted golf trolley is easy for a golfer to push around a golf course without becoming tired. It is lightweight and easy to store, similar to existing manual golf trolleys. The battery is small, lightweight, and charges quickly. The wheel assembly can be removed from the golf trolley for charging. 
         [0055]    It is understood that variations may be made in the foregoing without departing from the scope of the invention. For example, the elements and teachings of the various illustrative embodiments may be combined in whole or in part in some or all of the illustrative embodiments. In addition, one or more of the elements and teachings of the various illustrative embodiments may be omitted, at least in part, and/or combined, at least in part, with one or more of the other elements and teachings of the various illustrative embodiments. 
         [0056]    Although illustrative embodiments of the invention have been shown and described, a wide range of modification, changes and substitution is contemplated in the foregoing disclosure. In some instances, some features of the invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the invention.