WO2002024567A1

WO2002024567A1 - Winch assembly

Info

Publication number: WO2002024567A1
Application number: PCT/GB2001/003713
Authority: WO
Inventors: Nicholas Charles Henly
Original assignee: Lewmar Limited
Priority date: 2000-09-18
Filing date: 2001-08-17
Publication date: 2002-03-28
Also published as: GB0022849D0; AU2001278639A1

Abstract

A variable-speed drive assembly for a winch (10) for a water vessel such as a yacht includes an electric motor (12) controlled by a pulse-width modulator (26) and potentiometer (28).

Description

WINCH ASSEMBLY

The present invention relates to a winch assembly. More particularly, it relates to a winch assembly for use on a water vessel. Some winches used on water vessels are referred to as windlasses; for economy the term "winch" will be used in this specification for winches, windlasses and also for "gypsies", a specialised form sometimes used to haul anchor rodes (i.e. a rope and/or chain attached to an anchor) .

Winches are used on water vessels, and especially on yachts, to pull in rope. Usually, the winch is fixed to the deck of the yacht. Typically, the rope is attached to, for example, a sail. The rope (or "line") is usually expected to carry a variable load. Therefore the winch which pulls in the rope should be able to pull in a lightly loaded or loose rope as well as being able to pull in a heavily loaded rope. It is desirable to be able to pull in a lightly loaded or loose rope at speed. Similarly, it is desirable to be able to make slow, fine adjustments to the loaded length of a heavily loaded rope.

A winch may also be used to haul and lower an anchor rode . The load on the winch varies depending on the length of rode between the windlass and the anchor when the anchor is in the water. This load variability makes it difficult to control the speed of the winch.

Yacht winches can be manually driven or powered. The simplest manual winch has a manual input directly connected to an output, with no gearing or with a single gear. The speed of the output of such a winch is directly proportional to the speed of the input. More complex manual winches are known, these having multiple gearing ratios. These manual winches have a uni-directional (i.e. a single sense of rotation) output, the speed of the output depending on the speed and direction of rotation of the manual input . Powered winches can be powered by electric motors .

These electric motors typically have a single output speed.

Powered winches have a significant advantage over manual winches for the simple reason that they usually require less physical effort on the part of the user to operate them. This is particularly advantageous if the user is fragile. However, the manufacture of additional gearing to fit between an electric motor and a winch is complicated and is therefore expensive. Consequently, the manufacture of a powered electric winch with more than, for example, three output speeds is expensive. In addition, such gearing, by its nature, can only give stepped ratios of input speed to output speed. Such an arrangement is inflexible and cannot easily be altered once the arrangement has been assembled. In order to address the above problems, the present invention provides a winch assembly comprising: a winch; a power source; an electric motor; and speed control means, wherein the speed control means is operable to vary the speed of the motor between at least a minimum speed, an intermediate speed and a maximum speed, and the electrical motor drives the winch. The motor may be permanently coupled to the winch. The winch may be, for example, a deck winch or an anchor winch. The minimum speed of the motor may be zero.

Preferably the speed of the electric motor is variable substantially continuously. This may be achievable if the speed control means includes means for the control of the average electrical current delivered to the electric motor. Preferably, the means for the control of the average electrical current delivered to the electric motor includes means for the modulation of a pulse width of the electrical current delivered to the electric motor. Preferably the speed control means is programmable to set required discrete speed levels. Although in the basic system the speed of the electric motor (and hence the speed of the winch or windlass) is continuously variable, this preferred feature allows the user or equipment supplier, for example, to preset various preferred discrete speed levels of the motor.

Gearing between the electric motor and a drum of the winch may also be provided. Combined with the variable speed of the electric motor, multiple-ratio gearing allows the winch to be driven over an even wider range of speeds . The direction of rotation of the output from the electric motor may be reversible. Gearing may be provided which allows the winch to be driven in one direction of rotation at a speed which is determined by the speed and direction of rotation of the output from the electric motor .

Preferred embodiments of the invention will now be described by way of example only, with reference to the accompanying sole Figure which is a schematic diagram of a yacht deck winch assembly with an adjustable speed electric motor .

In the embodiment illustrated, the winch 10 mounted on a deck 11 of a water vessel such as a yacht is driven by a uni-directional DC electric motor 12. The electric motor is permanently connected mechanically to the winch by a right angled worm wheel gear box 14 through a connecting shaft penetrating the deck and entering a conventional drive input in the base of the winch. Typically, there is also gearing in the base of the winch. This determines the final drive ratio of the winch drum 16 in relation to the motor. The drum 16 will usually have the normal ability to overrun the drive when, e.g., rope is being tailed onto it. The electric motor 12 and speed controller 26 are both powered by a battery 18, typically a 12 V or 24 V battery.

The electrical circuit is protected from electrical damage by a circuit breaker 20. The electric motor is started by closure of the switch 22. This operates contactor 24 (via wire 15) to supply a positive potential from the battery to the motor by connecting wires 17 and 19. Operation of the switch also provides low-power current to the speed controller 26 via wire 25. The speed of the electric motor is controlled by the speed controller 26. Typically, speed controller 26 comprises at least one integrated circuit (IC) , which receives positive and ground reference potentials via wires 27 and 21 respectively. Wire 21 also completes the power circuit for speed controller 26. In the embodiment shown, the output of the speed controller is varied by operation of the potentiometer 28. If speed controller comprises an integrated circuit, potentiometer 28 is generally not arranged in series with the battery 18 and the electric motor 12, but connected to speed controller 26, which may compare its resistance against a reference resistance.

Typically, speed controller 26 comprises a pulse width modulator controller. Examples of pulse width modulator controllers are devices with model numbers PMC 1204/1205 available from Curtis Instruments UK Ltd., 51 Grafton Street, Northampton, NN1 2NT, UK.

The pulse width modulator controller is, in effect, a high powered semiconductor switch, consisting of an array of parallel power MOSFET transistors. The transistors are electrically connected in series with the battery and the motor via wire 23. The transistors are turned on and off approximately 15,000 times per second by the controller circuitry. Turning the transistors on and off has the effect of changing the potential on wire 23 from a low potential (which may be a ground potential) to a high potential, the high potential being the same as the potential on wire 27. This varies the potential difference between wires 27 and 23 (and therefore across electric motor 12) from 0 (transistors off) to a positive potential (transistors on) . The ratio of the on/off times is varied in response to the input from the potentiometer 28, which in turn is varied by the user. The relationship between the resistance of the potentiometer 28 and the output ratio of the pulse-width modulator may be linear.

Using the pulse width modulator controller, the current through the motor builds up, storing energy in the motor's magnetic field, when the transistors are on. When the transistors are off, the stored energy causes the motor current to continue to flow through a freewheel diode in the controller. The control current ramps up and down as the switch turns on and off. Average current, which determines motor torque, is controlled by the ratio of on/off time. The controller allows smooth, substantially stepless control of the power delivered to the motor with only a small power loss in the control components in the controller. Consequently, the speed of the motor is variable substantially continuously over the range from dead stop to full speed.

It is possible to replace the potentiometer 28 in the sole Figure with an array of fixed resistors and switches. The speed of the motor can then be controlled between fixed settings, these settings determined by the electrical resistance of the resistors. Alternatively, the resistance of the individual resistors may be variable. The resistance of the resistors could then be varied and set by the user, thus giving the motor (and hence the winch) a range of user-determined preset discrete speeds .

The advantage of having variable speeds is that the winch user is able to choose the most appropriate speed for the work he is doing. In particular, very fine low speed control is desirable when small adjustments are needed to the line (rope) load or loaded length. This is especially useful during racing conditions. Large adjustments to the length of the line between the winch and, for example, the sail attached to the end of the line, are possible if the speed of the winch is increased.

The speed controller described above can be retrofitted to an existing electric motor driven winch on a vessel. In some embodiments, the electric motor may be reversible and gearing in a separate gearbox or in the winch may give unidirectional drive at different ratios in accordance with the direction of rotation input.

The winch 10 may be substituted by an anchor winch or gypsy. The load carried by a yacht anchor winch during raising or lowering of the anchor varies according to the length of the anchor chain or line between the anchor and the winch. To compensate for the variable load carried by the winch, the amount of power delivered to the electric motor is varied by the speed controller. The speed of the winch may then be kept approximately constant even though the load on the electric motor is varying. This is particularly useful when raising the anchor, so that the anchor does not accelerate towards and collide with the yacht. In addition, the fine speed control of the electric motor allows the final stage of raising the anchor to the yacht itself to be performed slowly to avoid damage to the yacht . Whilst the present invention has been described in some detail, modifications and adaptations of these and further embodiments will be apparent to those skilled in the art. In particular, the skilled person will understand that the speed controller for the electric motor may be a device other than a pulse width modulator.

Claims

CLAIMS :

1. A winch assembly comprising: a winch; a power source; an electric motor; and speed control means, wherein the speed control means is operable to vary the speed of the motor between at least a minimum speed, an intermediate speed and a maximum speed, and the electric motor drives the winch.

2. A winch assembly according to claim 1, wherein the minimum speed of the motor is zero .

3. A winch assembly according to either claim 1 or claim 2, wherein the speed control means is operable to vary the speed of the motor substantially continuously between the minimum and maximum speeds .

4. A winch assembly according to claim 3, wherein the speed control means controls the speed of the motor by delivering pulses of electrical current to the motor and modulating the width of those pulses.

5. A winch assembly according to claim 4, wherein one input to the electric motor is conductively connected to a terminal of the power source and the speed control means varies the other input to the electric motor between a ground potential and the potential of the positive terminal of the power source .

6. A winch assembly according to claim 5 further comprising a switch and a relay and wherein operation of the switch causes the relay to close, thereby supplying a potential to one input of the electric motor, the potential to the other input being varied by the speed control means .

7. A winch assembly according to any one of the preceding claims, wherein the speed control means is programmable in order to set a plurality of discrete pre-set speed levels.

8. A winch assembly according to any one of the preceding claims, wherein the speed control means can vary the speed of the electric motor in both directions of rotation.

9. A winch assembly according to any one of the preceding claims, further comprising gearing through which the electric motor drives the winch.

10. A winch assembly according to any one of the preceding claims wherein the motor is permanently drivingly coupled to the winch.

11. A water vessel incorporating a winch assembly according to any one of the preceding claims.