WO1999056083A1 - Odometer - Google Patents

Abstract

A land vehicle mileage measuring system (1) comprises a processor (2), clock (5), movement sensor (6), memory (10), battery (9) and anti-tamper sensor (8) all enclosed in a housing (7). In operation the processor (2) processes mileage data and signals from the clock (5) and movement sensor (6), encrypts the resulting data and stores it in the memory (10).

Description

ODOMETER

This invention relates to a land vehicle mileage measuring system.

Most land vehicles are provided with a mechanical odometer which maintains a cumulative total of the mileage travelled by the vehicle. Conventional odometers are simple mechanical counters driven or controlled by electrical pulses or a direct mechanical drive, such as a cable drive, from a convenient part of the vehicle transmission. Generally in modern cars, the odometer is driven by electrical pulses generated by a sensor measuring rotation of the gearbox output shaft while in motor cycles the use of a direct cable drive driven by rotation of the front wheel is common.

Conventional odometers are simple geared mechanical counters and as a result, it, is normal for the mileage readings displayed on the odometer to be anything up to 5% higher or lower than the actual mileage travelled by the vehicle and this degree of accuracy is generally considered quite acceptable.

The main uses of the cumulative mileage total provided by the odometer are as a guide for scheduling routine maintenance and servicing of the vehicle and to indicate to potential buyers how much the vehicle has been used and the degree of accuracy of the odometer reading is acceptable for both purposes. Unfortunately, it is extremely easy to re-set the odometer to lower the mileage reading and so fraudulently increase the re-sale value of the vehicle. A similar problem is encountered in contract hire where the overall cost of a long term hire contract will in part be based upon the total mileage driven during the contract period to reflect the depreciation in the hired vehicles' value. As a result, it is possible for the vehicle hirer to dramatically reduce the cost of the contract either by winding the odometer back or by simply disconnecting the odometer drive for part of the hire period.

The ease with which odometer readings can be changed or the odometer can be disconnected has led to widespread fraud in the field of motor vehicle sales and contract hire and to an even higher level of suspicion of fraud. As a result of this suspicion, which in the case of purchase of used cars reaches the level of a virtual assumption of fraud, the prices of used cars are artificially depressed and the costs of : contract hire are artificially raised.

The present invention is intended to solve this problem, at least in part.

This invention provides a land vehicle mileage measuring system comprising mileage data supplying means for supplying mileage data signals to a processor, a clock for supplying clock signals to the processor, a movement sensor for providing movement signals to the processor, a memory and a power source to power the other, elements of the system, the processor processing the mileage data, clock and movement signals and storing data derived therefrom in the memory.

This allows the mileage travelled by the vehicle to be securely sensed and recorded and provides assurance that the mileage data stored within the system and the supply of mileage data to the system have not been interfered with.

A preferred embodiment of the invention will now be described with reference to Figure 1.

In Figure 1, a land vehicle mileage recording system 1 is shown. The system 1 includes a processor 2 which is supplied with vehicle mileage data signals along a first line 3 and vehicle ignition data signals along a second line 4 from remote sensors (not shown) . The system 1 further comprises a clock 5 which provides real time clock signals to the processor 2 and a motion sensor 6 which provides signals regarding movement of the vehicle to the processor 2.

The vehicle mileage data signals are pulses derived from rotation of a gearbox output shaft. All of the parts of the system 1 are housed within a sealed housing 7 which prevents moisture damaging the system components and prevents tampering with the system 1.

A tamper sensor 8 is provided which provides a tamper detection signal to the processor 2 if the sealed casing 7 is opened. An internal battery 9 is provided and has sufficient capacity to power all of the components of the system 1 for five years.

The processor 2 is able to encrypt data and is able to store the encrypted data in a memory 10 and to access data held in the memory 10. The processor 2 and the memory 9 preferably are formed monolithically as parts of a single semiconductor chip 11, but this is not essential.

A data input and output unit 12 is also connected to the processor 2. The data input and output unit 12 is able to cooperate with an inductive data transfer device (not shown) to periodically download data from the memory 10 to the data transfer device for inspection and processing and to provide new information or instructions to the system 1.

A light emitting diode 13 is provided which is visible from outside the casing 7 and is illuminated to show that the system 1 is functioning correctly.

Finally, a battery status unit 14 is provided to monitor the status of the battery 9 and to supply a battery status signal to the processor 2. If the voltage or other parameters of the battery 9 are such that operation of the system 1 will be impaired the, processor 2 will record this, together with the date and time, in the memory 10.

When the system 1 is to be fitted to a vehicle, the battery 9 is activated and the casing 7 sealed. The system 1 is then attached to the vehicle and the lines 3 and 4 providing the mileage data and ignition data signals are connected to the system 1. Proper operation of the system 1 and correct supply of mileage and ignition data signals is then confirmed through the data input and output unit 12 using the data transfer device. Then, data identifying the vehicle to which the system 1 has been fitted is supplied through the data input/output unit 12 and permanently stored in the memory 10 by the processor 2. This vehicle identification data will normally be the vehicle registration number but the vehicle chassis number and/or engine number could be used instead of or in addition to the registration number. If the system 1 is being fitted to a vehicle after manufacture the odometer reading at the time of fitting is also supplied and stored in the memory 10 by the processor 2. Data uniquely identifying the system 1 can also be stored in the memory 10 at this point or alternatively can be stored in the memory 10 on manufacture of the system 1. The data identifying the system comprises two serial numbers, the first serial number uniquely identifying the clock 5 and the second serial number uniquely identifying the chip 11. These serial numbers are, or are derivable from, corresponding numbers respectively physically etched onto the clock 5 and the chip 11. All of the data regarding the vehicle identity, system identity and initial odometer reading, if stored, is ..supplied to the system 1 and stored in the memory 10 in encrypted form to prevent replacement of the system 1 or the memory 10 with a new element containing false mileage data. The acceptance and storage of this data by the processor 2 is preferably password controlled to prevent replacement of the system 1 or memory 10 with a new unit.

Once activated, the processor 2 measures the resistance of each of the lines 3 and 4 providing the mileage data and ignition data. ,The processor 2 then encrypts the resistance values and stores the encrypted values in the memory 10.

In operation, the processor 2 processes the mileage data signal and the clock signals to produce a monthly sub-total of miles travelled each month by the vehicle, encrypts the monthly totals and then stores the encrypted monthly totals in the memory 10 together with an encrypted total of length of time for which the ignition was on for that month.

An encrypted cumulative total or totals is also maintained as a cross check. The processor 2 also monitors the ignition data signal and the vehicle movement signal to identify periods in which the ignition is on and/or the vehicle is moving but no mileage data signals are being received. Where the ignition is on and/or vehicle movement is sensed but no mileage data signals are being received for lengths of time exceeding respective predetermined threshold values stored in the memory 10, the processor 2 makes or updates stored encrypted values in the memory 10 giving the total length of time in each month for which the ignition was on and no mileage data was received, movement was sensed and no mileage data signals were received and the ignition was on and movement was sensed and no mileage data signal was received.

If the tamper switch 8 records an attempt to open the casing 7 , the processor 2 stores this information in the memory 10.

Periodically, for example weekly, the processor 2 measures the resistance of each of the lines 3 and 4 and compares the measured values with the corresponding values stored in the memory 10. If the measured and stored resistance values do not agree, the processor 2 stores the new measured resistance value together with the date and time of measurement, in encrypted form, in the memory 10. This allows attempts to interfere with the supply of mileage data and ignition data to the system 1 to be detected.

The stored data held in memory 10 can be periodically, for example at the end of a contract hire period, read out of the memory 10 by the processor 2 and passed to the data transfer device in encrypted form for decryption and analysis through the data input and output unit 12.

The processor 2 is programmed so that the processor 2 cannot delete or alter the data identifying the system and vehicle, the monthly totals of mileage, ignition on time or time for which ignition was on or movement sensed without mileage data signals, the stored resistance values or stored records of tamper switch 8 operation and battery status unit 14. The processor 2 is able to overwrite the cumulative totals and the sub-totals for the present month of course. However, these totals and sub-totals can only be altered in response to signals along lines 3 and 4 and from clock 5, and sensors 6 and 8 and not in response to instructions received through input/output unit 12. This ensures that even if the passwords allowing the data transfer device to access data in memory 10 are known, data already stored in the memory 10 cannot be fraudulently altered or deleted.

The monthly recorded mileage and ignition on time data together with the monthly ignition use and vehicle movement without mileage data signals data can be analyzed to provide a reliable record of the total vehicle mileage travelled. By comparing this value with the vehicle odometer reading, the accuracy of the reading of the normal vehicle odometer can be verified. In theory, the odometer reading should be identical to the total mileage recorded by the system 1. However it is likely that the system 1 will be significantly more accurate than a standard vehicle odometer so some discrepancy in the readings, generally up to approximately 5%, would be expected.

The system 1 is self contained apart from the data input wires and is physically small and so can be fitted covertly to vehicles without the user's knowledge. Attempts to defraud by re-setting the odometer can then easily be detected by the difference between the odometer reading and the total mileage recorded by the system 1. Further, attempts to defraud by disconnecting the wires or cable providing mileage data signals or the, mileage data drive to the odometer can be detected from the long periods of time for which the system 1 will have recorded that the vehicle ignition was on and that the vehicle was moving but no mileage data signals were being received, or from changes in the measured resistances of the lines 3 and 4.

Preferably the memory 10 is a non-volatile memory so that in the event of failure of or interference with the battery 9 all data stored up to the point of power loss can be recovered at a later date. The processor 2 will require appropriate passwords to be supplied by the data transfer unit before data held in the memory 10 can be accessed or altered in order to prevent unauthorised access to and interference with this data. Further, since the data held in the memory 10 is not decrypted by the processor 2, but is read out in its encrypted form and must be decrypted by the user, even if this data can be accessed the encrypted data will not be usable by unauthorised persons.

If desired, different passwords may be required to access or alter different data in the memory 10 in order to provide an hierarchial data security structure where different users have access to different data. For example, it may be preferred to allow the vehicle user to have access to the monthly mileage totals only. In such a case, either the processor 2 will need to be able to decrypt at least some of the data in the memory 10 or different users could be provided with appropriate means to decrypt only the data they are to have access to.

Any data should be encrypted by the processor 2 before being stored in the memory 10 in order to prevent unauthorised access to the data.

It is not essential that the information stored in the memory 10 identifying the vehicle and the system 1 be encrypted before it is supplied to the system 1 but this is desirable in order to prevent exchange of different systems 1 between vehicles or replacement of the system 1 with a new system 1.

The use of the casing 7 is not essential. The system 1 could be enclosed or encapsulated within a vehicle structural member so that no dedicated separate casing 7 was required. This would be particularly convenient if the system 1 were fitted to a vehicle during manufacture.

The ignition data signal supplied along line 4 to the processor 2 could be simply identifying whether the ignition is on or off. Alternatively, the ignition data signal could be derived from the actual ignition system pulses and thus could carry engine speed data. If such engine speed data is supplied, it could be used by the processor 2 to provide a further indication as to whether the vehicle is being driven when the ignition is on but no mileage data signals are being received. Further, comparison of the ignition data signal carrying engine speed data with the mileage data signal could be carried out by the processor 2 to identify any attempt to interfere with the mileage data signals without actually stopping them entirely.

Instead of being pulses derived from rotation of a gearbox output shaft the vehicle mileage data signals could have another format or be derived from some other convenient part of the vehicle. The vehicle mileage data signals could, for example, be pulses derived from wheel rotation, as generated by anti-lock brake systems (ABS) . Further, it would be possible to provide multiple vehicle mileage data signals to the system 1 derived from different locations, for example from all four wheel ABS units ..and from the gearbox output shaft. The processor 2 could then compare all of the received vehicle mileage data signals and record any discrepancies in the memory 10 in encrypted form. This provides a further means for detecting fraud attempts.

The system 1 could be powered from the vehicle electrical supply with the battery 9 being used only as a back-up to allow the system 1 to continue to function when the vehicle electrical supply was switched off or disconnected from the system 1. In tljis case it is convenient for the battery 9 to be rechargeable, recharging automatically from the vehicle electrical supply. Further, it is preferred that in this case the battery state sensor 14 monitors the status of both the system battery 9 and the battery of the vehicle electrical supply along an additional sensing line.

The use of a battery 9 able to power the system 1 for five years is not essential, a shorter period, or a longer period such as ten years may be convenient in some applications. The supply of ignition data signals to the system 1 is preferred but is not essential.

The use of the battery state sensor 14 is preferred but not essential.

If the system 1 is to be fitted to a vehicle without the vehicle users' knowledge, the correct functioning LED 13 is not required.

The memory 10 should be able to store the monthly data entries for at least five years or 150,000 miles distance of , normal driving.

In vehicles not having an ignition system, such as diesel engines, the ignition data signal should be replaced by some other signal showing engine operation.

The storage of monthly data is convenient but longer or shorter periods such as bi-monthly or weekly would be possible.

The maintenance of cumulative totals of mileage and ignition on time is convenient ,as a cross check, but is not essential.

The use of an inductive data transfer device allows contactless data transfer without opening the casing 7. However other forms of data transfer device could be used, for example an Infra-Red link or a plug in lead.

The physical etching of identifying numbers onto the clock 5 and chip 11 is not essential, but is desirable to prevent substitution of one system 1 for another.

In addition to recording a monthly and cumulative total of milage and ignition on time the system 1 could also record engine revolution numbers, when available in the ignition data signal, and driver behaviour data such as the use of speed, acceleration or engine speed exceeding pre-set thresholds. Alternatively samples of data could be recorded, depending on the total amount of data storage capacity in memory 10. This additional data can be used, particularly in a contract hire situation, to identify vehicles which have suffered improper use. The system 1 can be used to notify the vehicle user when routine maintenance such as servicing is required based upon time and milage. This is particularly effective if the additional data referred to above can also be used to determine when routine maintenance is required. In this case the LED 13, or an additional dedicated device, can be used to indicate when and/or what type of routine maintenance is required.

In the preferred embodiment described above a large number of encryption and password security features are included. It is not essential that all of these are used, but the greater the number used, the more secure the system 1 will be against interference. The stored and/or output data could of course be encoded instead of or in addition to being encrypted.

The person skilled in the art will realise that the above is only exemplary and changes could be made.

Claims

1. A land vehicle mileage measuring system comprising mileage data supply means for supplying mileage data signals to a processor, a clock for supplying clock signals to the processor, a movement sensor for providing movement signals to the processor, a memory and a power source to power the other elements, the processor processing the mileage data, clock and movement signals and storing data derived therefrom in the memory.

2. A system as claimed in Claim 1, and further comprising engine operation data supply means for supplying engine operation data signals to the processor, in which the data stored in the memory is also derived from the engine operation data signals.

3. A system as claimed ,in Claim 1 or Claim 2, and further comprising a sealed housing enclosing the processor, the memory, the clock, the movement sensor and the power source.

4. A system as claimed in Claim 3, and further comprising a tamper sensor for supplying a tamper indicating signal to the processor if the housing is opened.

5. A system as claimed in any preceding claim, in which at least some of the data stored in the memory is encrypted.

6. A system as claimed in any preceding claim, and further comprising a data output means for outputting data stored in the memory from the system.

7. A system as claimed in Claim 6, when dependent on Claim 5 , in which the encrypted data stored in the memory can only be output from the system by the data output means in encrypted form.

8. A system as claimed in any preceding claim, and further comprising a data input means for storing data from outside the system in the memory.

9. A system as claimed in any preceding claim, in which the memory stores data uniquely identifying the system.

10. A system as claimed in any preceding claim, in which the memory can store data identifying the vehicle to which the system is attached.

11. A system as claimed in Claim 6 in which the transfer of data from the memory by the data output means is password controlled.

12. A system as claimed in Claim 8 in which the transfer of data to the memory by the data input means is password controlled.

13. A land vehicle mileage measuring system substantially as shown in or as described with reference to the accompanying figure.