Device for protecting a motor vehicle controller against illicit exchange

An apparatus for preventing the replacement of a control unit, present in a motor vehicle, by an unauthorized person. The apparatus includes a function-inhibiting device, associated with a connection between the control unit and the connector element of an electrical supply lead, which immobilizes the control unit and the connection element in a predetermined connected position with respect to one another. Disconnection from this connected position without damage is possible only after delivery of an unlocking code to the control unit. If an attempt at forcible disconnection is made, the function-inhibiting device causes an irreversible interruption in the associated connection.

FIELD OF THE INVENTION
 The present invention relates to an electronic drive lock.
 BACKGROUND INFORMATION
 A conventional electronic drive lock is described in German publication
 "mot", February 1995, pages 102-106. Such a conventional drive lock is
 based on an access device in the form of an ignition key, a handheld
 transmitter (or a chip card), a control unit containing the drive lock,
 and an engine management control unit for controlling a gasoline or diesel
 engine. Other functional elements present in the vehicle can also be
 connected to the drive lock control unit, for example the electric fuel
 pump or the starter. A prerequisite for providing a vehicle equipped with
 the drive lock as described is that a prescribed unlocking code should be
 delivered to the drive lock control unit. Because the vehicle cannot, for
 this reason, readily be started up by an unauthorized person, the
 conventional drive lock offers at least some protection against theft,
 i.e. the vehicle being driven away. Given the increasing professionalism
 of vehicle thieves, however, it is foreseeable that vehicles will be
 misappropriated by replacing the original, locked drive lock control unit
 with an unlocked but otherwise functionally identical replacement control
 unit.
 Accordingly, it is the object of the invention to indicate a possibility
 for preventing the theft of vehicles by replacing a control unit.
 SUMMARY OF THE INVENTION
 This object is achieved with a device according to the present invention. A
 replacement protector according to the present invention considerably
 increases the effort required to steal a vehicle by replacing a protected
 control unit. In the event of forcible severing of a connection, secured
 according to the present invention, between the electrical supply lead and
 control unit, the electrical supply lead must be properly equipped with a
 connector element. For a vehicle thief, the effort to remove such
 replacement protector is cost-intensive and most of all time-consuming.
 For a legitimate user, on the other hand, the replacement protector
 according to the invention involves no additional effort when removing a
 protected control unit. It is advantageous, according to the present
 invention to provide a supply lead and a control unit with respect to one
 another in such a way that even when connected, a slight relative movement
 is possible. This makes it possible to eliminate any contact problems
 between supply lead and control unit by gently jiggling the connection,
 with no need to unlock the control unit for the purpose.

DETAILED DESCRIPTION OF THE INVENTION
 FIG. 1 shows, exemplary, a drive lock for motor vehicles which is locked
 and unlocked using of a magnetic card 33. The code stored on magnetic card
 33 is read by a card reader 32 which is connected via an electrical
 connection 21 to a drive lock control unit 30. Connected downstream from
 this via a further electrical connection 21 is an engine control unit 31
 which controls, among other things, ignition system 34 and fuel injection
 system 35. Also connected to drive lock control unit 30 is starter 36 and,
 if necessary, other control units present in the vehicle. Control units 31
 and 36 are enabled, thus making it possible to start up the vehicle, only
 if a correct unlocking code has been delivered to drive lock control unit
 30 by the use of an authorized magnetic card 33. The use of a magnetic
 card as the code carrier is exemplary only; any other conventional code
 delivery system can of course also be used. Other such systems may also
 include the common systems which operate in non-contact fashion. A more
 detailed diagram of the general layout of a conventional drive unit is
 provided in the publication `mot`.
 FIG. 2 shows the layout of a connection between one or more electrical
 connections 21 and a control unit 40. The control unit 40 can be drive
 lock control unit 30, card reader 32, engine control unit 31, or starter
 36. The control unit includes a housing 10 in which an electronic circuit
 14 is arranged. An exemplary illustration of electronic circuit 14 is
 shown in FIG. 2 having the form of a circuit board. Located on one side of
 housing 10 is a connector receptacle 15 in which one or more electrical
 connector pins 16 are arranged, which lead inside housing 10 to circuit
 14. Also located in control unit housing 10 is an actuator 11 which can be
 actuated using an electrical signal delivered externally. Actuator 11 may
 be advantageously configured as part of electronic circuit 14. Actuator 11
 moves one end of a lever 12 that is rotatable about a bearing shaft 17,
 the other end of Lever 12 being arranged outside housing 10 and inside
 connector receptacle 15. At the external end, lever 12 has a retaining pin
 13. Bearing shaft 17 is in turn mounted in connector receptacle 15 or in
 housing 10.
 Engaging with a precise fit into the connecting device mounted on the
 control unit, constituted by connector receptacle 15 with connector pins
 16 as well as levers 12 with retaining pins 13 located therein, is a
 connector element 20 to which are guided all the electrical supply leads
 21 to be connected to electronic circuit 14 arranged in the control unit.
 Connector element 20 is made up of a housing which encloses an interior
 space 25 in which electrical supply leads 21 end. One connector side 24 of
 the housing of connector element 20 is configured to fit precisely onto
 the contour of connector receptacle 15 mounted on the control unit.
 Located in connector side 24 of connector element 20 are recesses in which
 contact springs 22 are arranged, matched in terms of physical position to
 connector pins 16 on the control unit side. When a connection is made
 between connector element 20 and control unit 40, these springs coact with
 connector pins 16. Inside cavity 25, contact springs 22 extend into
 connector lugs 26, to each of which, as a rule, one electrical supply lead
 is guided. A defined break point 23 is configured in each case between
 connector lug 26 and the internal end of a contact spring 22. This break
 point can be implemented, for example, by reducing the cross section of
 connector lug 26 at one point, or by using a brittle, easily breakable
 material. At least some of contact springs 22 also have, in connector
 region 24, an opening 27 (shown in FIG. 3) whose axis lies substantially
 perpendicular to the direction along which contact spring 22 and connector
 pin 16 coact. Opening 27 is arranged so that when connector element 20 and
 control unit 40 assume a predetermined position with respect to one
 another, lever 12 with retaining pin 13 can be pivoted at its tip into
 opening. In one example embodiment of the present invention, an electrical
 transmitter circuit 52 (FIG. 5) generates an acknowledgment signal when
 the predetermined connected position is established.
 It is also advantageous that, opening 27 has the shape of a hole elongated
 along the effective direction of the connection between connector element
 20 and control unit 40. Control unit 40 (with housing 10) can, as a
 result, be moved slightly with respect to one another even if lever 12
 with retaining pin 13 is engaged in opening 27. Thus, if there is no
 electrical contact between a spring contact 22 and a connector pin 16, an
 attempt can first be made, by gently jiggling the connection at connector
 element 20 of control unit 40, to re-establish contact.
 The arrangement described above can be is utilized as follows. At each
 termination of a vehicle operation that took place after prior authorized
 startup, a signal is generated from card reader 32 or drive lock control
 unit 30 which authorizes actuator 11 to pivot lever 12 with retaining pin
 13 into opening 27 in contact spring 22 or connector pin 16. The coaction
 of retaining pin 13, lever 12, and the contact springs is illustrated in
 FIG. 3. If, in this state, connector element 20 and control unit 40 are
 forcibly disconnected, defined break point 23 in connector element 20
 breaks, causing contact springs 22 to be torn out of their mount in
 connector element 20, and the associated electrical connection 21 to be
 interrupted. A different control unit can no longer be connected to the
 vehicle by way of connector element 20 that has been damaged in this
 fashion.
 If, however, a control unit is to be removed or replaced with the consent
 of the legitimate owner, for example in the event of a defect or in the
 context of maintenance, a defined unlocking code signal is to be delivered
 for this purpose to the relevant control unit. This code signal can be
 generated only by a legitimate user who is in possession of the correct
 magnetic card 33. The code can be generated in various ways; in simple
 fashion, for example, the code is already located on magnetic card 33 and
 can be read out with an additional appropriate card reader. On the basis
 of the code signal, actuator 11, even in the shut-down state, pivots lever
 12 with retaining pin 13 out of opening 27, or causes the lever not to
 pivot into the opening into the first place, whereupon connector element
 20 can be disconnected from control unit 10 without damage.
 Retaining the basic conception of securing the connection between the
 connector element of an electrical supply lead and a control unit by means
 of a mechanical catch which acts perpendicular to the connection direction
 and can be actuated without damage only with the aid of a code signal, a
 plurality of embodiments of the arrangement whose principle is set forth
 in FIGS. 2 and 3 is possible. This applies, for example, to the nature and
 arrangement of actuator 11, the configuration of lever 12 with retaining
 pin 13, the nature and configuration of defined break point 23, or the
 number of catch devices. Interchanging of functions is also possible, the
 actuator being arranged in connector element 20 and defined break point 23
 in control unit 40.
 It is also possible to provide electrical retention instead of mechanical
 retention using retaining pin 13. For example, as illustrated in FIG. 4, a
 circuit breaker 44 and a battery 46 to power it can be provided in control
 unit 40, and a safety fuse 42 in connector element 20. If an unauthorized
 person attempts forcibly to sever the connection between the connector
 element and control unit 40, the circuit breaker feeds a high current into
 one of electrical connections 16, 21 in the connector element, which
 causes the safety fuse to be destroyed. Provision can also be made for the
 high current fed in by the circuit breaker to control unit 40 to cause
 destruction of the accessory powered by the relevant electrical connection
 16, 21, for example an engine speed sensor.