GB2597871A

GB2597871A - Improvements in or relating to stairlifts

Info

Publication number: GB2597871A
Application number: GB2116016.3A
Authority: GB
Inventors: Scott Pugh Gavin
Original assignee: Stannah Stairlifts Ltd
Current assignee: Stannah Stairlifts Ltd
Priority date: 2017-01-17
Filing date: 2017-01-17
Publication date: 2022-02-09
Anticipated expiration: 2037-01-17
Also published as: GB2558672B; GB2597871B; GB201700820D0; GB2558672A

Abstract

A stairlift has a carriage (5 fig.1) mounted on a rail (6 fig.1) and a battery charging facility which has a charge transmitter 20 mounted on or near the rail and a charge receiver 26 mounted on the carriage. The battery charger also includes a communications facility which may have an external communications interface operating wirelessly via coils 22, 25, including a data transmitter 32 and data receiver 31, to send data to a remote location. Data may be sent serially using phase shift keying (PSK) or amplitude methods. Various battery charging regimes may be programmed into the battery charger and may be manually selectable.

Description

IMPROVEMENTS IN OR RELATING TO STAIRLIFTS

Field of the Invention

This invention relates to stairlifts and, in particular, to a method of and/or apparatus for charging the battery or batteries of a battery-driven stairlift.

Background to the Invention

Currently battery powered stairlifts are powered from one or more lead acid batteries housed in the stairlift carriage. While some stairlift rails include a charging busbar extending along the length of the rail, in most cases the stairlift is provided with fixed charging contacts, typically at either end of the rail. To effect charging of the batteries, complimentary contacts on the carriage must be mechanically engaged with the fixed charging contacts on the rail and it is not uncommon for batteries to become discharged because the contacts on the carriage are not properly engaged with the contacts on the rail. Further, over time, the contacts can become misaligned and/or worn.

The charging contacts on the rail are connected to a charger. The charger may take a variety of forms because lead acid batteries are tolerant to a range of charging regimes However, as battery technology develops, charging regimes have to be tailored to specific battery types and this can lead to complication and expense, particularly if and when one battery type is substituted for another.

It is an object of the present invention to provide a method of and/or apparatus for charging a stairlift battery which goes at least some way to addressing the problems identified above; or which at least offers a novel and useful choice.

Summary of the Invention

Accordingly the invention provides a stairlift comprising a rail, a carriage mounted on said rail for movement along said rail; and a battery charging facility provided in part by a charger mounted on or adjacent to said rail and a charge receiver mounted on said carriage, wherein the stairlift includes a communications facility in said battery charging facility.

Preferably said charger is connected to, or incorporates, an external communications interface configured and operable to communicate data or messages to a remote location Preferably said charger and said charge receiver are configured to pass control signals from said charge receiver to said charger.

Preferably said charge receiver is configured with, or to receive, a plurality of different charging regimes.

Preferably said charge receiver is configured so that individual regimes are manually selectable or is configured to determine a battery type and to cause a charging regime to be applied appropriate to that type Preferably said charger and said charge receiver are configured to interact wirelessly Many variations in the way the invention may be performed will present themselves to those skilled in the art upon reading the following description The description which follows should not be regarded as limiting but rather, as an illustration only of one manner of performing the invention. Subject to the scope of the appended claims, where possible any element or component should be taken as including any or all equivalents thereof whether or not specifically mentioned.

Brief Description of the Drawings

One form of the invention will now be described with reference to the accompanying drawings in which: Figure 1: shows a schematic layout of a stairlift installation to which the present invention may be applied; Figure 2: shows a schematic diagram of a stairlift charging system according to the invention; and Figure 3: shows a typical charging characteristic for a stairlift battery.

Description of Working Embodiments

Referring to Figure 1, a stairlift installation comprises a stairlift carriage 5 mounted on a rail 6, the carriage 5 being displaceable along the rail by an electric motor and gearbox 7 mounted in the carriage and powered by one or more batteries 8. A pinion 9 mounted on the output of motor/gearbox 7 engages a rack 10 to effect drive. In the conventional manner a chair 11 is mounted on the carriage 5 upon which a user sits when the stairlift is in operation. A hand control 12 is provided on armrest 13 to enable the user to effect movement of the carriage and chair up and down the rail 6.

As shown the rail 6 has an upper end 14 and a lower end 15. Mounted on or close to the rail, at positions adjacent to the upper end 14 and lower end 15, are charge transmitters 16 which are connected to a battery charger 17. Mounted on the carriage is a charge receiver 18 which, when adjacent to one of the transmitters 16, receives charge which can be applied to the battery 8.

In accordance with a first aspect of this invention, charge is passed wirelessly from the charge transmitter(s) 17 to the charge receiver 18.

The charging system will be better understood with reference to Figure 2 in which those components to the left of the dotted line are fixed with respect to the stairlift rail 6 and comprise or include the charge transmitter 16 while those components to the right of the dotted line are mounted in, and are displaced with, the stairlift carriage 5 and comprise or include the charge receiver 18 In the form shown the fixed side of the system comprises a charger 20 which receives power from a mains fed power supply 21. Typically the power supply 21 is a 24 volt power supply. The fixed side further includes a wireless transmit coil 22 and a communications interface 23.

On the moving or carriage side, the system includes a wireless receive coil 25 and a charge receiver 26, the charge receiver 26 receiving power from the charger 20 via the coils 22 and 25. The charge receiver 26 rectifies the high frequency alternating current from the receiver coil 25 into direct current to charge one or more batteries indicated by block 27 As stated above, one important aspect of the invention is that power is passed wirelessly between the coils 22 and 25. This has the advantage that the coils do not have to be exactly aligned for charge to pass successfully and issues of mis-alignment and wear can largely be ignored. To this end the charge transmit coil will typically be positioned on or adjacent to the stairlift rail so that when the carriage is adjacent to a charge point the coils 22 and 25 will ideally be positioned in the order of lcm apart but will typically tolerate a spacing of 0 -3 cm in vertical spacing and 0 to 3 cm in lateral displacement. The coils 22 and 25 should not actually touch to avoid rubbing wear. These figures are based on a general rule that the maximum operational distance between the coils is in the order of 2/3 the diameter of the coils. In this instance we have chosen to use commercially available coils of 4.5 cm diameter.

Another important aspect of the invention is that the power receiver 26 can be configured to apply a variety of charging regimes to the battery 27 whilst maintaining a single common charger 20, one example of a charging regime being shown in Figure 3. In this way batteries based on different chemistry and having different designs can be substituted without the need to change the system hardware. Each charging regime is based on a particular battery type and/or design and is held either in a memory 28 associated with the charge receiver 11 or in the main control unit 30 of the stairlift. In the latter case, a particular charging regime can be transferred to the charge receiver 26 via a serial link.

Given the likelihood that a specific battery type or chemistry will be associated with particular stairlift model, the natural place to permanently store the charging regime will be in the main stairlift electronic control unit. This charging regime can then be serially transmitted to the power receiver board at the start up of the stairlift.

Referring to Figure 3, it can be seen that any charging regime will include varying voltage levels, current levels and stage timings depending on the specific battery type These can be reduced to a small set of parameters that can be transmitted to the charge receiver 26 at start up Another important aspect of the invention is that each charging regime may conveniently be effected by passing control signals from the power receiver 26 to the charger 20 using the charging coils 22 and 25. To this end, the charger 20 is provided with a communications receiver unit 31 and the charge receiver 26 is provided with a communications transmitter unit 32.

Given that, in operation, the coils 22 and 25 resonate together, communications may be effected by the well-known technique of phase shift keying using microprocessors/ microcontrollers incorporated in the units 20 and 26.

In broad terms the technique involves switching in or out a capacitor (or resistor) so that the resonant frequency of the whole system (receiver and transmitter) is shifted.

When two coils are resonating together because of their close proximity (i.e. transmitter and receiver coils) then they act much like a single coil. So by switching 'in' a capacitor on the charge receiver 26 the resonant frequency of the transmitter is also affected. This can be measured on the transmitter board by looking at the phasing of the transmitter waveform relative to the driving waveform on the transmitter electronics. This phasing measurement is effected by software running on the transmitter board and allows data bits of '0' and 'I'to be serially transmitted wirelessly from the receiver 26 to the transmitter or charger 20.

The alternative resistor method does not use frequency response but instead selectively loads the receiver coil 25 which weakens the amplitude in the transmitter 22 (higher current in the receiver generates an anti-phase magnetic field against the transmitter) This anti-phase field reduces back ENIF in the transmitter which causes a increase in transmitter coil current. The increased current in the transmitter causes a drop in amplitude on the transmitter side which can be detected by the transmitter software.

An added benefit of the communications functionality is that other data relating to the operation of the stairlift such as, for example, diagnostic data, usage data, and user help requests can be sent along the same pathway and relayed to a remote location using interface 23, the interface 8 typically comprising an internet router or WiFi interface.

It will thus be appreciated that the present invention, at least in the case of the embodiment described, has a number of advantages including i) Problems associated with charge point wear and mis-alignment are largely obviated, A universal charger may be adapted to charge batteries of different types and having different charging regimes The charging system can also provide a communications portal.

Claims

Clanns A stairlift comprising a rail; a carriage mounted on said rail for movement along said rail, and a battery charging facility provided in part by a charger mounted on or adjacent to said rail and a charge receiver mounted on said carriage, wherein the stairlift includes a communications facility in said battery charging facility.A stairlift as claimed in claim 1 wherein said charger is connected to, or incorporates, an external communications interface configured and operable to communicate data or messages to a remote location.A stairlift as claimed in claim 1 or claim 2 wherein said charger and said charge receiver are configured to pass control signals from said power receiver to said charger.A stairlift as claimed in any one of claims 1 to 3 wherein said charge receiver is configured with, or to receive, a plurality of different charging regimes.A stairlift as claimed in claim 4 wherein said charge receiver is configured so that individual regimes are manually selectable or is configured to determine a battery type and to cause a charging regime to be applied appropriate to that type A stairlift as claimed in any one of claims 1 to 5 wherein said charger and said charge receiver are configured to interact wirelessly