GB2093593A

GB2093593A - Method of and equipment for sensing speed of travel

Info

Publication number: GB2093593A
Application number: GB8105498A
Authority: GB
Original assignee: University of Surrey
Current assignee: University of Surrey
Priority date: 1981-02-20
Filing date: 1981-02-20
Publication date: 1982-09-02

Abstract

The speed of a track mounted vehicle (1) is sensed by equipment comprising a plurality of units (4 to 11) arranged in a preselected spaced formation along the vehicle track (2). As the vehicle travels along the track the presence of each unit is detected in sequence by sensor means (13) fixedly mounted on the vehicle, the sensor means deriving a train of signals which is indicative of the sequential passage of the units and which is fed to signal processing means (15, 16) to sense the period of time elapsing between the detection of two adjacent units in the spaced formation. The sensed time period may be compared with a fixed reference time in order to activate a braking system of the vehicle. Preferably the spacing of the units (4 to 11) varies according to maximum safe speeds of the vehicle along different portions of the track. <IMAGE>

Description

SPECIFICATION Methods of and equipment for sensing speed of travel This invention relates to methods of and equipment for sensing speed of travel.

In particular, although not exclusively, the present invention relates to methods of and equipment for sensing the speed of vehicles movable along fixed paths and for actuating vehicle brake means should the sensed vehicle speed tend to reach above a preselected value.

One problem associated with known such speed sensing equipment is that once the equipment is set to actuate the vehicle brakes when the preselected speed is sensed, the equipment always will apply the brake when that speed is reached irrespective of the position of the vehicle location along its path.

Consequently, once such prior known equipment is fitted to a vehicle its maximum speed along the full length of the vehicle path is fixed.

In an underground mine the profile of a track for a rail mounted vehicle frequently can vary significantly along the length of the vehicle path, particularly when the path negotiates relatively safe, substantially straight and level sections of track followed by potentially dangerous, steeply inclined or sharply curved sections of track, necessitating speed restriction. With prior known speed sensing equipment the maximum speed of the vehicle along the full length of its path is limited to a relatively low value determined by the potentially dangerous section of the track.

In an attempt to increase the efficiency of such a transport system including locomotives it has been proposed to provide a manual override for the speed sensing equipment whereby a locomotive driver can override the action of the speed sensing equipment along the relatively safe sections of track enabling the locomotive to travel at higher speed. Unfortunately, such a proposal suffers from the disadvantage that if the driver should fail to disengage the override action then the locomotive may be allowed to travel along the potentially dangerous section of the track at potentially dangerously high speeds.

An object of the present invention is to provide a method of and equipment for sensing speed of travel which tends to overcome or reduce the above mentioned problems.

Accordingly, one aspect of the present invention provides a method of sensing the relative speed of travel between a component and an elongate arrangement, wherein a plurality of units are arranged in a preselected spaced formation along the elongate arrangement, and sensor means fixedly mountable relative to the component such that, in use, when there is relative movement between the component and the elongate arrangement, the presence of each unit is detected in sequence by the sensor means which thereby derives a train of signals indicative of the sequential passage of the units, the train of signals being fed to signal processing means including timing means to sense the norinol or r,+timp PlnnRinCI between the detection of two adjacent units in the spaced formation.

Conveniently, the spacing between adjacent units varies along different sections of the elongate arrangement.

Preferably, the component is a mobile vehicle and the elongate arrangement is a preselcted path along which the vehicle travels.

Preferably, comparator means are provided for comparing each sensed period of time elapsing between the detection of two adjacent units with a preselected period.

Preferably, the comparator means is arranged to derive a vehicle brake activating signal if a sensed period of time is equal to or less than the preselected period.

According to another aspect the present invention provides equipment for sensing the relative speed of travel between a component and an elongate arrangement, comprising a plurality of units arrangeable in a preselected spaced formation along the elongate arrangement, sensor means fixedly mountable with respect to the component such that, in use, when there is relative movement between the component and the elongate arrangement, the presence of each unit is detected in sequence by the sensor means, the sensor means being adapted to derive a train of signals indicative of the sequential passage of the units, and signal processing means including timing means for receiving the derived train of signals to sense the period of time elapsing between the detection of two adjacent units in the spaced formation.

Preferably, the component is a mobile vehicle and the elongate arrangement is a preselected path along which the vehicle travels.

Preferably, each unit induces a magnetic field adjacent to the associated unit, the induced magnetic field being detectable by the sensor means comprising a magnetic detector.

By way of example, one embodiment of the present invention now will be described with reference to the accompanying drawing which shows diagrammatically speed sensing equipment constructed in accordance with the present invention.

In the drawing a rail mounted vehicle 1 is shown travelling along an elongate path (only a portion of which is shown) defined by a rail track 2, the vehicle having rail engaging wheels 3 at least some of which are driven by a prime mover (not shown) mounted on the vehicle.

A plurality of magnetised units 4 to 11 are arranged along a preselected spaced formation extending along the full length of the track (as previously mentioned only a small portion of the track is shown in the accompanying drawing). It will be noted that the units 4,5 and 6 associated with a substantially level section of track are relatively widely spaced whereas units 7 to 11 associated with a relatively steeply inclined section of rack are relatively closely spaced.

The vehicle 1 is provided with sensor means constituted by a magnetic detector 13 fixedly mounted with respect to the vehicle and arranged such that in use, when the vehicle is travelling along the track the detector detects the presence of each unit in sequence. Upon detecting the presence of the units in turn the sensor means is adapted to derive a train of signals indicative of the sequential passage of the units by the detector, the derived train of signals being fed along line 14to signal processing means 15 including clock means 16. The processing means sense the period of time elapsing between the detection of two adjacent units in the spaced formation (6 and 7, or 7 and 8, or 8 and 9 etc).

Comparator means 17 are provided for comparing each sensed period of time elapsing between the detection of two adjacent units with a preselected period, the comparator means being adapted to derive a vehicle brake activating signal if a sensed period of time is equal to or less than the preselected period. The derived vehicle brake activating signal is fed along line 18 to a vehicle brake 19 which is activated upon receipt of the signal into a brake applied mode, simultaneously shutting off the power source.

Thus, in use, when the vehicle is travelling along the relatively safe, substantially level section of track associated with the relatively widely spaced units 4, 5 and 6 the vehicle is permitted to travel at relative high speed before the sensed period of time elapsing between the detection of adjacent units is sufficiently short for the comparator means 17 to derive a vehicle brake activating signal. Thus, whilst travelling along the relatively safe, substantially level section of track the vehicle is permitted to travel at relatively high speeds.

Upon the vehicle entering the potentially dangerous, steeply inclined section of track associated with the relatively closely spaced units 7 to 11, the vehicle is permitted to travel at only a relatively slow speed before the sensed period of time elapsing between the detection of adjacent units is sufficiently short for the comparator means 17 to derive a vehicle brake activating signal and the vehicle brake to be applied.

Thus, if the vehicle should tend to run away down the incline out of control the excess speed is quickly sensed by the speed sensing equipment and the vehicle brake is automatically applied.

Thus, it will be appreciated that the present invention tends to provide improved safety brake equipment particularly suitable for use with underground mine transport systems.

The magnetic detector 13 may comprise a fluxgate magnetometer, a reed switch or Hall devices.

In other embodiments of the invention the magnetised units may be replaced by any suitable means offering a binary discrimination to the sensor head, for example electro magnetic wave means, optical means and/or mechanical means.

In other embodiments of the invention for use with rope hauled vehicles or winding instaliations the sensor means may remain stationary with the space formation provided on the rope.

Claims

1. A method of sensing the relative speed of travel between a component and an elongate arrangement, wherein a plurality of units are arranged in a preselected spaced formation along the elongate arrangement, the sensor means are fixedly mountable relative to the component such that, in use, when there is relative movement between the component and the elonate arrangement, the presence of each unit is detected in sequence by the sensor means which thereby derives a train of signals indicative of the sequential passage of the units, the train of signals being fed to signal processing means including timing means to sense the period of time elapsing between the detection of two adjacent units in the spaced formation.

2. A method as claimed in claim 1, wherein the spacing between adjacent units varies along different sections of the elongate arrangement.

3. A method as claimed in claim 1 or 2, in which the component is a mobile vehicle and the elongate arrangement is a preselected path along which the vehicle travels.

4. A method as claimed in claim 3, in which comparator means are provided for comparing each sensed period of time elapsing between the detection of two adajcent units with a preselected period.

5. A method as claimed in claim 4, in which the comparator means is arranged to derive a vehicle brake activating signal if a sensed period of time is equal to or less than the preselected period.

6. Equipment for sensing the relative speed of travel between a component and an elongate arrangement, comprising a plurality of units arrangeable in a preselected spaced formation along the elongate arrangement, sensor means fixedly mountable with respect to the component such that, in use, when there is relative movement between the component and the elongate arrangement, the presence of each unit is detected in sequence by the sensor means, the sensor means being adapted to derive a train of signals indicative of the sequential passage of the units, and signal processing means including timing means for receiving the derived train of signals to sense the period of time elapsing between the detection of two adjacent units in the spaced formation.

7. Equipment as claimed in claim 6, the spacing between adjacent units varies along different sections of the elongate arrangement.

8. Equipment as claimed in claim 6 or 7, in which the component is a mobile vehicle and the elongate arrangment is a preselected path along which the vehicle travels.

9. Equipment as claimed in claim 8, in which comparator means are provided for comparing each sensed period of time elapsing between the detection of two adjacent units with a preselected period.

10. Equipment as claimed in claim 9, in which the comparator means is arranged to derive a vehicle brake activating signal if a sensed period of time is equal to or less than the preselected period.

11. Equipment as claimed in any one of the preceding claims 6 to 10, in which each unit induces a magnetic field adjacent to the associated unit, the induced magnetic field being detectable by the sensor means comprising a magnetic detector.

12. A method of sensing the speed of travel of a vehicle travelling along a preselected path substantially as described herein with reference to the accompanying drawing.

13. Equipmentforsensing the speed of a vehicle along a track, substantially as described herein and substantially as shown in the accompanying drawing.