GB2075261A - Switch means responsive to tilting - Google Patents

Abstract

A structure such as a fork lift truck has at least one switch (30) responsive to tilt of that structure. The switch comprises a pendulum (31) for swinging a first contact (35) in response to a tilt into electrical contact with a second contact (36) to provide at least one electrical signal, e.g. for control purposes, for instance enabling or disenabling operation of at least one function of a fork lift truck. The switch comprises a third contact (39) arranged so that the first contact (35) can fall into contact with the second and third contacts (36, 39) if the first contact (35) should separate from its pendulum (31), whereby the first, second, and third contacts will complete an electrically conductive path suitable e.g. for disenabling operation of the fork lift truck. <IMAGE>

Description

SPECIFICATION Switch means responsive to tilting A structure, or at least one portion of a structure, might tilt. Such tilting can be produced in any way.

One example is when land subsides under a building (e.g. a bridge, house, or tower), scaffolding, or a machine. Another example is when use of a structure produces such tilting. For instance, a vehicular structure (e.g. a fork lift truck) might tilt when on a slope, or when the vehicular structure is used in such a way as to shift its centre of gravity. If a structure is adapted to provide at least one function, and is liable to tilt at any time, there is a problem of what to do about said at least one function when the structure tilts. For instance, when the structure is a vehicle, it can be desirable to dis-enable traction means for driving the vehicle. If the vehicle has at least one hydraulically operated function (e.g. a fork lift), it can also be desirable to dis-enable the hydraulic means.

In this way, the risk of tilt increasing to a dangerous amount might be reduced or prevented.

It has now been found in accordance with the present invention that at least one switch means can be provided responsive to at least a portion of tilt of a structure and/or responsive to at least a portion of tilt of at least one portion of said structure.

According to a first aspect of the present invention, there is provided a structure, comprising at least one switch means responsive to at least a portion of tilt of said structure and/or responsive to at least a portion of tilt of at least one portion of said structure, wherein said switch means comprises: pendulum means; first electrode means, said pendulum means being able to swing said first electrode means in an interval of distance, this swinging being responsive to at least one portion of at least one said tilt; and second electrode means arranged with said interval between said first electrode means and said second electrode means, so that said swinging first electrode means will swing into electrical contact with said second electrode means.

According to a second aspect of the present invention, there is provided switch means, comprising: pendulum means; first electrode means, said pendulum means being able to swing said first electrode means in an interval of distance, this swinging being responsive to at least one portion of tilt of said switch means; and second electrode means arranged with said interval between said first electrode means and said second electrode means, so that said swinging first electrode means will swing into electrical contact with said second electrode means.

It will be appreciated that a said switch means can be of far greater sensitivity and scope than a spirit level. Said switch means can be used in any suitable application. Said switch means can provide at least one electrical signal. At least one said signal can be used for dis-enabling or enabling traction means for driving a fork lift vehicle, and/or dis-enable or enable hydraulic means of such a vehicle. However, at least one said signal can be used remote from a said structure, e.g. in remote control of a fork lift vehicle.

A vehicular structure is a preferred embodiment of said first aspect of the present invention. Said vehicular structure can be a land vehicle, e.g. a fork lift truck, a lorry, or a train. Said vehicular structure can be a water vehicle, e.g. a barge or other kind of boat. Said vehicular structure can be an air vehicle, e.g. a helicopter or a hovercraft. The present invention can be applied in carrying out my UK patent applications 7934868 and 7936011. The whole contents of those applications are hereby incorporated into the present application. The application 7934868 relates to a boom for lifting or lowering a load. That boom can be comprised by a fork lift vehicle. The application 7936011 relates to a fork lift vehicle having an elevatable platform.

Said pendulum means can be any suitable pendulum means. The pendulum means can comprise a simple pendulum or a compound pendulum for swinging said first electrode means. In one embodiment, said pendulum means comprises a swingable resilient arm (e.g. an electrically conductive wire) for swinging said first electrode means. In another embodiment, said pendulum means comprises a swingable rigid arm (e.g. an electrically conductive rod) for swinging said first electrode means. Fulcrum means for said pendulum means can be provided in any suitable way, and can be suitably resilient or rigid. Said pendulum means can be adjustable or of a fixed nature, appropriate to the required swinging of said first electrode means. For instance, the length of the pendulum and/or its plumb mass (which can form part of said first electrode means) can be adjustable.Any suitable material can be used for constituting said pendulum means. For instance, said pendulum means can comprise material for enabling said pendulum means to be temperature compensated. Preferably, said pendulum means is adapted to prevent or reduce risk of resonance of said pendulum means. For instance, this can be provided by utilising suitable fulcrum means and an electrically insulating fluid in which said first electrode means will be swung. Said pendulum means can have any suitable arc of swing, for establishing said electrical contact between said first electrode means and said second electrode means. Preferably, said arc of swing corresponds to a range of angles up to substantially 5" either side of a datum vertical plane.Preferably, said pendulum means comprises or constitutes at least one electrically conductive path for enabling an electrical potential to be supplied to said first electrode means. Preferably, that electrical potential is a negative D.C. potential.

This path can be constituted in any suitable way, e.g.

comprise an electrically conductive wire that is a said swingable resilient arm. Preferably, the path leads to terminal means for said switch means, but it could lead to e.g. any other electrically conductive path provided as part of said switch means, see later below in respect of third electrode means.

Said first electrode means can be constituted in any suitable way. Preferably, said first electrode means is a single first electrode means. In one embodiment, said single first electrode means is an electrically conductive block, e.g. a cubic block as described later below in respect of third electrode means.

Said second electrode means can be constituted in any suitable way. Preferably, said second electrode means is a single second electrode means, preferably in a closed figure (e.g. a circle) around said first electrode means, with said interval between said first electrode means and said second electrode means. However, it will be appreciated that said second electrode means can be a plurality of second electrode means that surrounds said first electrode means, with said interval between said first electrode means and said plurality of second electrode means.Said plurality of second electrode means can comprise separate second electrode means spaced apart from each other in any suitable way, e.g. with predetermined angular spacings such that when electrical contact is made between a said first electrode means and at least one said second electrode means, at least one signal can be provided that will give at least one indication of where tilt is being applied to said vehicle orto at least one portion of said vehicle.

A vessel can comprise or constitute said second electrode means. For instance, at least one portion of of an inner surface of a vessel can comprise or constitute at least one said second electrode means.

Conveniently, an electrically conductive vessel or an electrically conductive surface of a vessel is a said second electrode means. It will be appreciated that an electrically conductive surface can be constituted in any suitable way, e.g. be material constituting a wall of a vessel or be a coating or an insert secured to a wall of a vessel, for instance an electrically plated surface or a surface provided by means of vacuum deposition our a bar set into a recess in that wall. Preferably, a said vessel contains electrically insulating fluid. Such a fluid can comprise liquid and/or gas. Preferably, said fluid comprises an oil of mineral origin (e.g. any suitable single refined mineral oil or blend of refined mineral oils available from the petroleum industry), and/or an oil of synthetic origin (e.g. a silicone oil).It will be appreciated that the properties of said fluids can enable said switch means to be embodied in various ways, e.g. the density, viscosity, and/or viscosity index of an oil of mineral origin can be such that the switch means will satisfy various requirements of use, for instance temperature of use, or the time taken for said swinging first electrode means to contact electrically said second electrode means, or the time taken for said falling first electrode means to contact electrically said third electrode means, or provide mechanical damping in said vessel so as to resist or prevent resonance of said pendulum means. Preferably, said fluid will have fire extinguishing properties and not be flammable. Any suitable pressure can be provided in said vessel, but it is preferred that the pressure in said vessel is atmospheric at least during use of said switch means.Said vessel can be compensated against e.g.

undesirable change in pressure within said vessel, for instance against increase in pressure resulting from an undesirable expansion of said fluid. For instance, at least a portion of said vessel can be adapted to expand or contract in response to change in volume of said fluid, e.g. said vessel can have a bellows portion. If desired, said vessel can have chamber means or duct means into which expanding fluid can enter. Such entered fluid can return in any suitable way from said chamber means or duct means, e.g. be discharged therefrom by means of a spring biassed piston or other biassing means. It is expected that in many applications (e.g. a said vehicle according to the present invention) said vessel will be a rigid vessel not having any said compensation, and said fluid will be chosen approp' riately.

Preferably, said switch means is adapted so that if said first electrode means falls from said pendulum means, said first electrode means will fall into electrical contact with said second electrode means.

Said switch means can be adapted to aid such directional falling, e.g. said switch means can comprise deflector means for aiding at least a portion of said directional falling and which can be constituted in any suitable way, e.g. by means of suitably shaped surface of third electrode means (see later below).

Said switch means can comprise at least one further electrode means, e.g. so as electrically to contact said falling or fallen first electrode means.

Preferably, said switch means comprises third electrode means for electrically contacting said falling or fallen first electrode means, so that said fallen first electrode means, said second electrode means, and said third electrode means will be in an electrically conductive path. Preferably, this path is electrically connected to at least one electrically conductive path mentioned earlier above (for enabling an electrical potential to be supplied to said suspended first electrode means). This electrical connection can be constituted in any suitable way, e.g. externally of said vessel and by means of an electrically conductive lead bridging terminals connected respectively to said first electrode means and said third electrode means.

Said switch means can be adapted so that the time for establishing electrical contact between said falling first electrode means, said second electrode means, and said third electrode means will be in a predetermined time range. One ready way of changing that range is to change the density of fluid in said vessel.

Said third electrode means preferably has shaped surface for aiding at least a portion of said directional falling. Said first electrode means can also have shaped surface for cooperating with said shaped surface of said third electrode means, during said directional falling of said third electrode means.

Preferably, said suspended first electrode means has a polygonal shape in a vertical plane, e.g. an oblong rectangle or a square rectangle. Said third electrode means can have at least one sloping surface in a vertical plane, so as to provide suitable deflection of said falling polygonal first electrode means. Preferably, said third electrode means has a triangular shape in a vertical plane, this shape constituting said at least one sloping surface. Preferably, said first electrode means is an oblong rectangular block or a square rectangular block. Preferably, said third elec trode means is a conical block. It will be appreciated that said third electrode means can be provided in any suitable way so that impact of said falling first electrode means with said third electrode means is convenient.For that purpose, said third electrode means can be resiliently or rigidly mounted, as appropriate.

Preferably, said first electrode means is at a negative D.C. potential, said second electrode means is at a positive D.C. potential, and said third electrode means is at said negative D.C. potential.

Said switch means can be connected to at least one electrical circuit. For example, a said circuit can comprise at least one control means and/or at least one indicator means that can receive at least one said signal from at least one said switch means. A simple example of control means is a relay operable by at least one said signal. A said control means can be adapted to respond to at least one predetermined value of at least one said signal, and/be adapted to respond to at least one electrical mode of said switch means. It will be appreciated that when said first electrode means is electrically connected to said second electrode means and said third electrode means, this mode can be regarded as a logic one state of said switch means; whereas when that connection does not exist, this absence can be regarded as a logic zero state of said switch means.

Thus, said switch means can be of interest e.g. to digital processing of electrical signals. A said control means can be adapted to enable or dis-enable at least one function of a said vehicle, and/or be adapted to enable or dis-enable at least one function of at least one portion of said vehicle, in response to the electrical mode of at least one said switch means. For instance, by using a said relay, a said switch means can be used to make or break (or make and break) any number of electrical circuits. Energis ing of the coil of a said relay can result in switching off of the electrical supply to hydraulic circuits and traction circuits of a vehicle having such circuits, together with operating at least one indicator means.

At least one indicator means can be adapted to respond to at least one said switch means and/or respond to at least one said control means. For instance, a said indicator means can give at least one acoustic indication and/or at least one visual indica tion, responsive to at least one said switch means and/or responsive to at least one said control means.

W A said indicator means can be constituted in any suitable way. For instance, a said indicator means can comprise at least one indicator light, e.g. an incandescent light and/or a light emitting diode. In another instance, a said indicator means comprises an alarm horn.

A display means can be adapted to respond to any of: at least one said switch means; at least one said control means; and at least one said indicator means. A said display means can be constituted in any suitable way. For instance, a said display means can comprise any suitable cursor (e.g. a pivoted needle) and/or counter means. A said display means can be electronic, e.g. a cathode ray tube display, or a display utilising liquid crystal means.

The present invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a schematic view of one fork lift truck; Figure 2 is a schematic view of another fork lift truck; Figure 3 is a schematic view of one embodiment of switch means for use by means of the fork lift truck of Figure 1 or Figure 2.

In Figure 1, a longitudinally extensible telescopic arm 1 constitutes an extensible boom for lifting or lowering at least one load. At a first end portion of the arm 1 is mounted a removable work platform 2.

At the other end portion of the arm 1, the arm 1 is pivotally mounted about an axis of rotation constituted by a spindle 3 of trunnion means mounted on an elevatable support platform 4 carried by means of the forks 5 of the mast 6 of the truck. There are two forks 5 side by side and inserted into respective pockets in the support platform 4. At each side of the arm 1 is a respective hydraulic cylinder 7. The first end portion of each cylinder 7 comprises a respective piston 8 pivotally connected to a respective upper portion 9 of the arm 1, at a location between the spindle 3 and a variably positionable centre of gravity 10 of arm 1. The other end portions of each cylinder 7 are pivotally mounted each about a respective axis of rotation constituted by a spindle 11, there being respective spindles 11 for each cylinder 7.The spindles 11 are parts of respective trunnion means mounted on the elevatable support platform 4. The locations of the spindles 11 are between the variable centre of gravity 10 and the spindle 3.

A switch 12, in accordance with Figure 3, is mounted on the elevatable support platform 4, or at any other suitable location on the fork lift truck, so as to be able to provide output signals to control means 13 e.g. mounted on the platform 4. The control means 13 will respond in at least one predetermined manner, e.g. trigger predetermined safety operations. Thus, when the platform 4 tilts sufficiently to operate the switch 12, the switch 12 sends a signal to the control means 13, which can then dis-enable the electrical supply to the hydraulic circuitry and traction circuitry of the fork lift truck. The control means 13 can activate indicator means (not shown) for switching on an indicator lamp and a horn.

In Figure 2, a fork lift truck 21 has two elevatable forks 22 side by side (one is shown). The forks 22 are for insertion into respective pockets 23 mounted to the underneath of a platform 24 elevatable by means of the forks 22. The forks 22 are mounted to an elevator system present in mast 25 of the fork lift truck 21. A switch 26, in accordance with Figure 3, and a switch 27, in accordance with Figure 3, are respectively mounted to e.g. platform 24 and the mast 25. If desired, only one of these switches can be provided. The switches 26, 27 are identical switches.

When a switch 26 or 27 is tilted to provide an output signal, the output signal passes to control means 28 mounted on e.g. fork lift truck 22. The control means 28 will respond in at least one predetermined manner, e.g. trigger predetermined safety operations. Thus, when a switch 26 or 27 is sufficiently tilted, that switch sends a signal to the control means 28, which can then dis-enable the electrical supply to the hydraulic circuity and traction circuity of the fork lift truck. The control means 28 can activate indicator means (not shown) for switching on an indicator lamp and a horn.

In Figure 3, there is shown a switch 30, suitable for use as switch 12 in Figure 1 or as switch 26 or 27. The switch 30 has an electrically conductive wire 31 leading upwards to a terminal 32 mounted in electrically insulating bush 33 received in a plug 34.

The bottom end of the wire 31 suspends an electrically conductive cubic block 35 constituting a first electrode. The block 35 is swingable in all vertical planes by means of the wire 31 resiliently swinging in response to tilting of the switch 30. If this tilting is sufficientthe block 35 will be swung into electrical contact with an electrically conductive cylinder 36 surrounding but spaced apart from the vertically suspended block 35. The cylinder 36 constitutes a second electrode. It leads upwards to a terminal 37 provided on the top of plug 34. The plug 34 is electrically conductive and provides an electrically conductive path including the cylinder 36.

An electrically conductive plug 38 similar to plug 34 is in said electrically conductive path including the cylinder 36. Mounted centrally on the upperface of the plug 38 is an electrically conductive conical block 39 constituting a third electrode. The block 39 leads downwards to a terminal 40 mounted in an electrically insulating bush 41 provided in the plug 38. The terminal 40 is connected by means of a wire linkage 42 to terminal 32, thereby providing an electrically conductive path including these terminals and outside cylinder 36.

If the cubic block 34 should fall from its suspension wire 31, the block 35 will fall onto the conical block 39, and thereby be directed into contact with the cylinder 36, as shown by the representation 43 of the fallen block 35. In this way an electrically conductive path is provided including the fallen block 34, the conical block 39, and the cylinder 36.

Within the cylinder 36 is an electrically insulating liquid 43, e.g. at least one oil of mineral origin. This liquid will resist resonance of the pendulum constituted by the suspension wire 31, and will act as a damper to prevent erratic contact of the cubic block 35 with the cylinder 36.

Switch 30 can be made of any suitable materials and be of any suitable size. Plugs 34 and 38 can be secured in any suitable way to cylinder 36, e.g. one or both of those plugs can be screwed into the cylinder 36.

The present invention can be used e.g. to ensure that mast 6 or mast 25 remains vertical when the fork liftvehicle is on level or sloping ground.

The present invention extends to equivalents of the above description of the drawings and their representation. In general, the present invention can be embodied in any suitable way. Thus, the present invention also extends to equivalents of the various possibilities thereof discussed in the above description given before the description of the accompanying drawings. It will be appreciated that a structure according to the present invention can be any structure to which a said switch means will respond, e.g. a building, scaffolding, a machine, or a vehicle.

At least one signal from at least one said switch means can be used in providing e.g. levelling to counteract, reduce, or remove at least a portion of at least one said tilt. Thus, at least one levelling means is an optional feature of the present invention. It will be appreciated that the present invention can be applied in providing controlled tilting of a structure or in controlled tilting of at least one portion thereof, whether or not that tilting is provided by means of said levelling. Thus, at least one tilt means is an optional feature of the present invention. For instance, the hydraulic circuitry discussed with reference to Figure 1 can comprise or constitute at least one said levelling means and/or at least one said tilt means.

Claims (39)

1. A vehicle, comprising at least one switch means responsive to at least one tilt of said vehicle and/or responsive to at least one tilt of at least one portion of said vehicle, wherein said switch means comprises: first electrode means, adapted to be swingable in an are of swing; pendulum means, adapted to swing said first electrode means in response to at least a portion of at least one said tilt; and second electrode means, arranged with an interval between said first and second electrode means, such that said first electrode will be able to swing in said interval and into electrical contact with said second electrode means and provide at least one electrical signal.

2. A vehicle as claimed in claim 1, wherein said first electrode means is constituted by a single electrode.

3. A vehicle as claimed in claim 2, wherein said first electrode means is constituted by a plurality of electrodes.

4. Avehicle as claimed in any one of claims 1 to 3, wherein said arc of swing is any angle up to substantially 5".

5. A vehicle as claimed in any one of claims 1 to 4, wherein said pendulum means is a simple pendulum.

6. Avehicle as claimed in any one of claims 1 to 4, wherein said pendulum means is a compound pendulum.

7. A vehicle as claimed in any one of claims 1 to 6, wherein said pendulum means comprises a swingable resilient arm for providing said swinging of said first electrode means.

8. A vehicle as claimed in any one of claims 1 to 6, wherein said pendulum means comprises a swingable rigid arm for providing said swinging of said first electrode means.

9. A vehicle as claimed in any one of claims 1 to 8, wherein said pendulum means is adapted to prevent or reduce at least part of any resonance in said swinging of said first electrode means.

10. Avehicle as claimed in any one of claims 1 to 9, wherein said second electrode means at least partly surrounds said first electrode means with said interval therebetween.

11. A vehicle as claimed in any one of claims 1 to 10, wherein said second electrode means is disposed in a cylindrical or annular disposition.

12. A vehicle as claimed in any one of claims 1 to 11, wherein said second electrode means is constituted by a single electrode.

13. A vehicle as claimed in any one of claims 1 to 11, wherein said second electrode means is constituted by a plurality of electrodes.

14. Avehicle as claimed in any one of claims 1 to 13, wherein said switch means comprises a vessel wherein are disposed said first and second electrodes and at least a portion of said pendulum means.

15. A vehicle as claimed in claim 14, wherein said vessel contains electrically insulating fluid, said first electrode means being swingable in that fluid.

16. Avehicle as claimed in claim 15, wherein said fluid comprises oil of mineral origin.

17. Avehicle as claimed in claim 15 or 16, wherein said fluid comprises oil of synthetic origin.

18. A vehicle as claimed in any one of claims 1 to 17, wherein said switch means is adapted so that if said first electrode means falls from said pendulum means, said first electrode means will fall into contact with said second electrode means.

19. Avehicle as claimed in claim 18, wherein said switch means comprises third electrode means, adapted for contacting said fallen first electrode means so that said first electrode means, said second electrode means, and said third electrode means will complete an electrically conductive path.

20. A vehicle as claimed in claim 19, wherein said electrically conductive path extends externally of said vessel so as to connect said first and second electrodes externally of said vessel.

21. A vehicle as claimed in claim 19, wherein in a vertical plane, said first electrode means has a polygonal shape for assisting constitution of said electrically conductive path.

22. Avehicle as claimed in claim 21, wherein said polygonal shape is an oblong rectangle.

23. A vehicle as claimed in claim 22, wherein said polygonal shape is a square rectangle.

24. A vehicle as claimed in any one of claims 19 to 23, wherein said third electrode means has a shape adapted to cam said falling first electrode means into electrical contact with said second electrode means.

25. A vehicle as claimed in claim 24, wherein in a vertical plane, said third electrode means has at least one inclined surface for providing said camming of said falling first electrode means.

26. A vehicle as claimed in any one of claims 1 to 25, wherein said vehicle and/or said switch means comprises at least one electrical circuit means responsive to at least one electrical state of said switch means, so as to enable and/or disenable, and/or indicate, and/or display at least one functional mode of said vehicle.

27. A vehicle as claimed in claim 26, wherein at least one said electrical circuit means is adapted so that when said first, second, and third electrode means complete an electrically conductive path, at least one functional mode of said vehicle will be enabled and/or disenabled.

28. A vehicle as claimed in claim 27, wherein at least one said electrical circuit means is adapted so that when said first, second, and third electrode means complete an electrically conductive path, operation of said vehicle will be disenabled.

29. A vehicle as claimed in any one of claims 1 to 28, wherein said vehicle is a vehicle having elevatable fork lift means.

30. A vehicle as claimed in claim 29, wherein at least one said switch means is mounted to said elevatable fork lift means.

31. Avehicle as claimed in claim 29 or 30, wherein at least one said elevatable fork lift means supports work platform means; and at least one said switch means is mounted to said work platform means.

32. A vehicle as claimed in claim 29 or 30, wherein at least one said elevatable fork lift means supports elevatable boom means; and at least one said switch means is mounted to said boom means.

33. A vehicle as claimed in claim 32, wherein said boom supports work platform means; and at least one said switch means is mounted to this work platform means.

34. Avehicle as claimed in any one of claims 1 to 33, wherein said vehicle is a land vehicle.

35. A vehicle as claimed in claim 34, wherein said vehicle is a fork lift truck.

36. A vehicle as claimed in claim 1, substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

37. A switch adapted to be switch means suitable for use in accordance with any one of claims 1 to 36.

38. A switch as claimed in claim 37, substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.

39. A structure other than a vehicle, comprising at least one switch as claimed in claim 37 or 38.