GB2293881A

GB2293881A - Vehicle speed etc. alarm.

Info

Publication number: GB2293881A
Application number: GB9420143A
Authority: GB
Inventors: Isabel Joseph
Original assignee: Individual
Current assignee: Individual
Priority date: 1994-10-06
Filing date: 1994-10-06
Publication date: 1996-04-10
Also published as: GB9420143D0

Abstract

A vehicle speedometer or revolution indicator system is fitted with means of alerting the driver when his vehicle reaches pre-set upper or lower speed limits. The said speed limits may be set either manually, using controls within the vehicle, or automatically by roadside telemetry systems. The speedometer etc. 1 has a needle 5 and sensors 2, 3 which are adjustable by knobs 4 to alter the limits. The needle 5 may carry metallic foil 6. A signal from a sensor is fed to an amplifier, and then to a processor unit, and then to a visible or audible alarm. <IMAGE>

Description

Vehicle Speed Alarm This invention relates to alarm devices for vehicles to alert drivers that they have reached or exceeded certain limits of speed.

Speed meters, commonly called "speedometers" are fitted to most motor vehicles and are well known. They are manufactured using various technologies and commonly employ a combination of electronic and mechanical engineering expertise.

According to the present invention, a sensor is fitted to a vehicle's speedometer system (either during the manufacture of the speedometer or subsequently) which detects when the vehicle's speed has reached a pre-set limit. At this point a visual or audible alarm is activated. A possible extension to this system is a second sensor which detects when the vehicle's speed falls below a specified limit. Such an extension may act as a "doze alarm" to alert the driver that he may be becoming sleepy or that for some other reason he is not maintaining a steady vehicle speed.

Similar systems may be used in connection with the vehicle's engine revolution counter to help the driver to keep engine speeds within economic or safety limits.

There is a variety of ways in which such systems may be implemented. In the manufacture of speedometers or revolution counters, mechanical or electronic sensors may be incorporated having means of adjusting the limits at which alarms are activated. As an accessory kit, which may be fitted to vehicles subsequently to original manufacture, sensors may be attached to the front of the speedometer or revolution counter which will detect the presence of the instrument's needle.

Alternatively, a sensor unit may be introduced into the flexible drive cable to the speedometer or may be coupled to the electronic speed pick-off system used for many speedometers and revolution counters.

Two specific embodiments of the invention will now be described by way of example with reference to the accompanying drawings in which: Figure 1 shows a typical speedometer with sensors fitted to its transparent display cover.

Figure la is a side view of the speedometer shown in Figure 1.

Figure 2 shows a schematic of the alarm system components associated with the type of sensor system typically illustrated in Figure 1.

Figure 3 shows a typical arrangement in which the speedometer drive cable is fitted with a sensor unit.

Figure 4 shows a schematic of the alarm system components associated with the type of sensor system typically illustrated in Figure 3.

Examnle 1 Figures 1 and la show a speedometer (1) to which two sensors (2) have been mounted on pointers in front of the conventional speedometer dial. The location of the sensors can be adjusted by the driver using control knobs (4) at the centre of the speedometer. (The second sensor may not be fitted if only one speed is to be detected.) As the speedometer needle (5) reaches the location of the sensor(s) its presence is detected electromagnetically, capacitatively, or by other means and an alarm is triggered. In the case of speedometers with non-magnetic needles, a piece of metallic foil (6) may have to be fitted to the needle. Figure 2 illustrates the schematic of the circuitry to which the sensor(s) is coupled. A signal from each sensor is typically fed to an amplifier (7) and then to a signal processor unit (8), the output from which is fed to an alarm unit (9).The signal processor performs such functions as determining the precise point at which the alarm is triggered and it may have means of determining the length of time for which the alarm operates.

In its simplest form the alarm is triggered whenever the speedometer needle passes the sensor but a more sophisticated version may have means of detecting whether the speed is increasing or decreasing. This information can be used to prevent the alarm being activated when speed is being reduced from above an upper limit or increased above a lower limit, thus avoiding unnecessary warnings reaching the driver.

The alarm unit drives either visible (10) or audible (11) alarms (or both) which attract the driver's attention to the speed limit (upper or lower) being reached.

Example 2 Speedometers are typically operated in one of two ways. They are either driven mechanically by a flexible cable from the vehicle's transmission system or, (usually in newer vehicles), they are electronically driven and the speed is sensed by a magnetic pick-off unit mounted at some point in the transmission system of the vehicle. In this example a speed pick-off unit is fitted in the flexible drive cable (if a mechanical drive is used) or the vehicle's existing pick-off unit is used to drive the electronic system directly. Figure 3 illustrates a speed sensor (12) fitted in the existing drive cable (13) between the speedometer (14) and the vehicle's gearbox (15). Figure 4 is a schematic of the electronic circuitry which may be connected to it or to an existing speedometer pick-off unit. The electronic system comprises circuitry to monitor pulse rate (16) from the speed pick-off having means of calibration such that pulse rate can be made to represent speed. Signals from the pulse monitor unit are fed to an alarm trigger unit (17) which has means (18), either in the form of controls on the vehicle control panel or by road-side telemetry systems (or a combination of both), of setting speed limits at which alarms are to be sounded. Signals from the alarm trigger unit (17) are fed to the alarm unit (19) which activates either a visible (20) or audible (21) alarm (or both).

Claims

CLAIMS:

1. A vehicle speedometer system in which means are provided for the operation of visible, audible or other alarms in the event that pre-set speeds are exceeded or, in the case of minimum speed limits, when the vehicle speed falls below the said limits.

2. A vehicle speedometer system substantially as claimed in Claim 1 wherein detectors are mounted on the front of a speedometer such that the presence of the speedometer needle is used to detect when the speed of the vehicle has reached a preset limit.

3. A vehicle speedometer system substantially as claimed in Claim 1 wherein a signal derived from a speed pick-off device is used to operate alarm trigger circuitry when pre-set speed limits are reached. The speed pick-off may either be fitted to a mechanical speedometer drive cable or may be the source of vehicle speed information for driving an electronic speedometer.

4. A vehicle speedometer system substantially as claimed in Claims 1, 2 and 3 wherein the speed limits are pre-set remotely, for example by means of a radio telemetry link system, such that automatic resetting of the said limits occurs as the local conditions and mandatory speed limits change.

5. A system substantially as claimed in Claims 1,2 and 3 but applied to the engine revolution counter system of a vehicle.

6. A vehicle speedometer or engine revolution counter system substantially as claimed herein with reference to the accompanying drawings.