Abstract:
A vehicle security system includes a vehicle ignition switch, a door lock actuator, a primary vehicle entry and ignition control circuit, a backup vehicle access control circuit and a key including a principal vehicle control subsystem and a backup vehicle entry circuit. Advantageously, the system is devoid of any ignition lock cylinder, any door lock cylinder and any key blade thereby reducing vehicle manufacturing costs. A related method is also provided.

Description:
TECHNICAL FIELD 
       [0001]    This document relates generally to the vehicle equipment field and, more particularly, to an electronic vehicle security system that eliminates the use of key blades and is devoid of lock cylinders for the doors and ignition switch of the vehicle. 
       BACKGROUND 
       [0002]    Pin tumbler locks in the form of cylinder locks have been used in vehicles for generations to limit access to and operation of the vehicles to authorized individuals in possession of a key matching those cylinder locks. Generally these cylinder locks include an outer casing or cylinder, a plug held in that cylinder, a keyway in the plug to receive a key blade and a set of spring-loaded key pins and corresponding driver pins. 
         [0003]    The key blade is cut to a particular pattern or shape and is inserted into the keyway in order to operate the lock. When an improper key is inserted into the keyway, the key pins straddle the shear point where the plug meets the cylinder housing preventing the lock from opening or the ignition switch from turning to start the vehicle. In contrast, when the proper key is inserted into the keyway, the pins rise causing the meeting points of the key pins and cooperating driver pins to all align along the shear point where the plug meets the cylinder housing. This allows the plug to rotate thereby opening the door lock or turning the ignition switch of the vehicle. 
         [0004]    For many years now vehicles have also incorporated an electronic security, immobilizer or magnetic coupled transponder system on the ignition switch. More specifically, the ignition switch includes an induction coil and the key is provided with a cooperating winding connected to a transponder. When the key is inserted into the keyway of the ignition switch, the induction coil is activated and sends out an electromagnetic field of energy. The windings associated with the transponder absorb that energy and power the electronic transponder to emit a signal. Typically the signal is an alphanumeric sequence that is considered an identification or key code. The induction coil reads the signal and sends it to the ignition control module. If the signal is recognized as an accepted identification code for authorized operation of the vehicle, other electronic components in the vehicle are set in the motion to allow the vehicle to start and the engine to continue running. 
         [0005]    Essentially the new electronic immobilizer systems based on transponders are superior to key lock cylinders. They provide more than a billion unique combinations versus thousands of unique combinations for key lock cylinders. The electronic immobilizer systems have effectively rendered ignition key lock cylinders redundant secondary systems that are unnecessary. Thus, key lock systems are a legacy of an earlier age of vehicle design that now effectively add unnecessary cost to vehicle production. 
         [0006]    This document relates to a vehicle security system devoid of any ignition lock cylinder, any door lock cylinder and keys including cut key blades for operation of such cylinders. 
       SUMMARY 
       [0007]    In accordance with the purposes and benefits described herein, a vehicle security system is provided. That system comprises a vehicle ignition switch, a door lock actuator, a primary vehicle entry and ignition control circuit, a backup vehicle access circuit and a key. The primary vehicle entry and ignition control circuit is connected to the ignition switch and the lock actuator. The backup vehicle access control circuit is connected to the lock actuator. The key includes a principal vehicle control circuit and a backup vehicle entry circuit. Advantageously the vehicle security system is devoid of any ignition lock cylinder, any door lock cylinder and any key blade cut to operate any such lock cylinder. 
         [0008]    In one possible embodiment the primary vehicle entry and ignition control circuit includes a receiver and a body control module powered by a primary vehicle power supply. The backup vehicle access circuit includes a backup power supply and a backup access control module. Further the principal vehicle control circuit includes a first actuator, a controller and a transmitter powered by a principal power source. The backup vehicle entry circuit includes a second actuator and a backup controller powered by a backup power source. 
         [0009]    In one possible embodiment the vehicle security system further includes a passive entry circuit. That passive entry circuit includes a presence or touch sensor, a passive entry control module and a low frequency transmitter. In addition the key further includes a low frequency receiver. 
         [0010]    Significantly, the vehicle security system allows the vehicle manufacturer to utilize a single key fob housing with a plurality of control buttons whether the key is for a passive entry passive start (PEPS) vehicle or a non-passive entry passive start (nPEPS) vehicle. The only difference between the two types of keys is the internal circuitry. This further allows the manufacturer to reduce production costs associated with a vehicle. 
         [0011]    In some embodiments a key fob housing is provided having a plurality of control buttons. Further the key includes a common ignition switch engagement feature that is used to manually engage the ignition switch to start a nPEPS vehicle. In one possible embodiment the common ignition switch engagement feature is formed by the key fob housing. 
         [0012]    In accordance with an additional aspect, a method is provided for reducing the cost of vehicle production. That method includes the steps of (a) equipping the vehicle with an electronic security system controlling vehicle entry and ignition and (b) omitting any ignition key lock cylinder from the vehicle. The method may further include omitting any door key lock cylinder and/or omitting any key blade from a key of the vehicle. In addition, the method may include providing a key fob with a common ignition switch feature and using that key fob as standard equipment for both PEPS and nPEPS vehicles that are manufactured. 
         [0013]    In the following description, there is shown and described several preferred embodiments of the vehicle security system. As it should be realized, the vehicle security system is capable of other, different embodiments and its several details are capable of modification in various, obvious aspects all without departing from the vehicle security system and related method as set forth and described in the following claims. Accordingly, the drawings and descriptions should be regarded as illustrative in nature and not as restrictive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The accompanying drawings incorporated herein and forming a part of the specification, illustrate several aspects of the vehicle security system and together with the description serve to explain certain principles thereof. In the drawings: 
           [0015]      FIG. 1  is a perspective view of the front of a key fob used in conjunction with the vehicle security system. 
           [0016]      FIG. 2  is a schematic block diagram of the electronic components of a nPEPS key fob consistent with the vehicle security system. 
           [0017]      FIG. 3  is a schematic block diagram of the electronic components of the vehicle security system of a nPEPS vehicle responsive to the nPEPS key illustrated in  FIG. 2 . 
           [0018]      FIG. 4  is a schematic block diagram of the electronic components of a key fob for a PEPS vehicle. 
           [0019]      FIG. 5  is a schematic block diagram of the electronic components of the vehicle security system for a PEPS vehicle operated by the PEPS key fob illustrated in  FIG. 4 . 
       
    
    
       [0020]    Reference will now be made in detail to the present preferred embodiment of the vehicle security system, examples of which are illustrated in the accompanying drawings. 
       DETAILED DESCRIPTION 
       [0021]    Reference is now made to  FIGS. 1-5 , which considered together, fully illustrate the electronic vehicle security system  10 . A key  12  for the system  10  is illustrated in  FIG. 1 . The key  12  includes a key fob housing  14  and a plurality of control buttons  16   1 - 16   5 . In the illustrated embodiment, the control button  16   1  is depressed to lock a door or the doors of the associated vehicle V. Control button  16   2  is depressed to unlock a door or the doors of the vehicle V. Control button  16   3  is depressed in order to unlock the trunk lid of the vehicle V. Control button  16   4  is depressed in order to cause the vehicle to sound an emergency alarm. Finally, control button  16   5  is depressed to utilize the backup system to unlock the door of the vehicle in a manner that will be described in greater detail below. 
         [0022]    As further illustrated in  FIG. 1 , the key  12  also includes a common ignition switch engagement feature  18  which may be inserted into and received in the ignition switch  44  of the nPEPS vehicle V as described in greater detail below in order to manually start and operate the vehicle when desired. In the illustrated embodiment the common ignition switch engagement feature  18  comprises a projecting rectangular lug with two opposing notches  20 . Here it should be appreciated that the feature  18  may assume substantially any desired shape so long as the feature is common. By “common” it is meant that the feature  18  is standard equipment and may be received in substantially any ignition switch  44  on substantially any nPEPS vehicle V produced by that manufacturer. This commonality functions to reduce production costs without sacrificing security in any manner. 
         [0023]    In one particularly useful embodiment, the key fob body or housing  14  and the common ignition switch engagement feature  18  are integrally molded together. More specifically, the key fob housing  14  and feature  18  are assembled from two molded sections  22   a  and  22   b  that are secured together after inserting the electronic components of the key  12  which are held within an internal cavity formed by those sections. 
         [0024]    Reference is now made to  FIG. 2  schematically illustrating the electronic components found in a key  12  to be used to control the operation of a vehicle V by means of a nPEPS system. 
         [0025]    More specifically, the key  12  includes a housing  14  which contains a principal vehicle control circuit  24  and a backup vehicle entry circuit  26 . More specifically, the principal vehicle control circuit  24  includes a microprocessor controller or electronic control unit (ECU)  28 , a cooperating actuator, such as push button  16   2 , and a radio frequency transmitter  32  incorporating an antenna  34 . As illustrated, the principal vehicle control circuit  24  is powered by a principal power source  36  identified in the figure as the “primary battery”. 
         [0026]    The backup vehicle entry circuit  26  comprises a backup controller  38  in the form of a microprocessor controller or ECU, and a second actuator in the form of a push button  16   5  for activating the controller  38 . As illustrated, the backup vehicle entry circuit  26  is powered by a backup power source  42  identified in the drawing figure as the “backup battery”. 
         [0027]    The key  12  illustrated in  FIG. 2  allows the owner or operator to control entry into and operation of the vehicle V schematically illustrated in  FIG. 3 . That vehicle includes a vehicle ignition switch  44  and at least one door lock actuator. In the illustrated embodiment, the vehicle V includes four door lock actuators  46   1 - 46   4 . Actuator  46   1  operates the lock on the front left-hand or driver&#39;s door. Actuator  46   2  operates the lock on the front right-hand or passenger door. Door actuator  46   3  operates the lock on the rear left-hand side door while actuator  46   4  operates the lock on the rear right-hand door. 
         [0028]    As further illustrated in  FIG. 3 , the vehicle also includes a primary vehicle entry and ignition control circuit  48  including a body control module or ECU  50  and a radio frequency receiver  52  connected to an antenna  54 . The primary vehicle entry and ignition control circuit  48  is powered by the primary vehicle power supply such as a battery  56 . In addition vehicle V includes a backup vehicle access circuit  57  including a backup vehicle access controller or ECU  58  powered by a backup power supply  60 . 
         [0029]    In operation, the vehicle operator approaches the vehicle V, holds the key  12  and depresses the control button  16   2  to unlock the driver&#39;s door of the vehicle. When the button  16   2  is depressed, the controller  28  activates the radio frequency transmitter  32  to transmit a security code over the antenna  34  toward the vehicle V. The radio frequency receiver  52  of the primary vehicle entry and ignition control circuit  48  within the vehicle V receives the code and sends it to the body control module (BCM)  50  for entry authorization. If the BCM  50  recognizes the code as authentic to the vehicle, the BCM  50  sends a signal to the door lock actuator  46   1  which is then activated to unlock the driver&#39;s side door. After entering the vehicle, the operator inserts the common ignition switch engagement feature  18  into the receiver of the ignition switch  44  and turns the ignition past the on position to the start position. When this is done an induction coil  45  in the ignition switch  44  sends out an electromagnetic field of energy. The windings  64  absorb that energy and power the transponder  66  in the key  12  to emit a coded signal. That coded signal may be an alphanumeric sequence which functions as an identification code. The induction coil  45  reads that signal and sends it to the BCM  50 . In the event the BCM  50  recognizes the signal as an operator authorized code, BCM  50  initializes other electronic components of the vehicle to allow the starting of the vehicle V and continued operation thereof. 
         [0030]    The above description assumes that the principal power source  36  in the key  12  has the necessary charge to allow the principal vehicle control circuit  24  to operate normally. In the event the principal power source  36  does not have the necessary charge to provide normal function of the principal vehicle control circuit  24 , when the operator depresses the control button  16   2 , nothing will happen and the vehicle door will remain locked. In this situation the operator then depresses the backup control button  16   5 . The backup power source  42  provides the necessary power to the backup vehicle entry circuit  26  for the backup controller  38  to activate the transmitter  32  causing it to send the security code over the antenna  34  to the vehicle receiver  52  thereby initiating the unlocking of only the driver&#39;s door through backup door controller ( 58 ). Thus, it should be appreciated that the backup vehicle entry circuit  26 , and its isolated power source  42  provide an electronic backup mechanism allowing entry into the vehicle V even when the primary battery  36  is discharged or is not functioning properly. It is important to note the backup system will not allow the car to start if the ECU or power supply battery ( 56 ) are not working. It only allows the user to get inside the car and take protection from the elements. 
         [0031]    In the event, the primary vehicle power supply  56  has lost charge for any reason and is unable to power the primary vehicle entry and ignition control circuit  48 , the backup vehicle access circuit  57  will unlock the driver&#39;s door by means of actuator  46 . More specifically, the receiver  52  will transmit the security code received from the transmitter  32  to the backup controller  58 . Upon recognizing the code as authentic, the controller  58  will send a signal to the door lock actuator  46 , to unlock the driver&#39;s door and allow access to the vehicle V. 
         [0032]    Reference is now made to  FIG. 4  which illustrates a key  14  for a vehicle equipped with a PEPS system. The key  14  includes a principal vehicle control circuit  70  and a backup vehicle entry circuit  72 . 
         [0033]    The principal vehicle control circuit  70  includes a controller  74  connected to a radio frequency transmitter  76 , having an antenna  78 , and a low-frequency receiver  80 , connected to an antenna  82 . The controller  74  is activated by the first actuator or push button  16   2 . As further illustrated, the principal vehicle control circuit  70  is powered by the principal power source or primary battery  84 . 
         [0034]    The backup vehicle entry circuit  72  includes a backup controller  86  activated by the second actuator or push button  16   5  and powered by the backup power source or battery  88 . 
         [0035]    Reference is now made to  FIG. 5  illustrating the vehicle V with a PEPS system that cooperates with the key  12  illustrated in  FIG. 4 . 
         [0036]    As illustrated, the vehicle V includes an ignition switch  90  and at least one door lock actuator. In the illustrated embodiment four door lock actuators  92   1 - 92   4  are provided. Door lock actuator  92   1  activates the lock on the front left-hand or driver&#39;s door. Door lock actuators  92   2 - 92   4  are connected to the other doors of the vehicle V. 
         [0037]    The vehicle V also includes a primary vehicle entry and ignition control circuit  94  comprising the body control module or ECU  96  and the radio frequency receiver  98 . The primary vehicle entry and ignition control circuit  94  is powered by the primary vehicle battery  100 . 
         [0038]    The vehicle V also includes a backup vehicle access or driver door circuit  101  which comprises the backup controller  102  which is powered by a backup battery  104 . 
         [0039]    Still further, the vehicle V includes a PEPS operating system or passive entry circuit  106  including a PEPS control module or ECU  108 , a low-frequency transmitter  110  and a presence, touch or capacitive sensing system or sensor  112 . 
         [0040]    In normal operation, the operator approaches the vehicle V and inserts his hand into the door handle cavity of the driver&#39;s side door with the intention of pulling the handle. This breaks a capacitive field and the presence sensor  112  sends a signal to the PEPS control module  108 . In response the PEPS control module  108  sends a signal causing the LF transmitter  110  to admit a low-frequency signal. The LF receiver  80  in the PEPS key  14  detects that signal and then sends an appropriate signal to the controller  74  which in turn sends a control signal to the RF transmitter  76  which transmits a key code over the antenna  78  toward the vehicle V. The vehicle receiver  98  receives the signal and sends it to the BCM  96  to determine the signal authenticity. Upon confirming the proper key code, the BCM sends a signal to the door lock actuator  92   1  to unlock the lock on the driver&#39;s side door. 
         [0041]    The passenger then completes the seamless opening the door with the handle, gets into the vehicle V and closes the door. The BCM  96  then establishes through sensors that the key  12  is inside of the vehicle. When the driver pushes the ignition button  114  of the ignition switch  90 , the BCM  96  or other engine start electronic control unit allows the engine to start after again confirming the key code. 
         [0042]    In the event the primary battery  84  of the key  12  does not have a sufficient charge to drive the principal vehicle control subsystem  70 , when the operator depresses the push button  16   2 , nothing happens. In this situation the operator may then depress the backup push button  16   5  activating the back controller  86  powered by the backup battery  88 . Here it should be noted that the electrical circuit powered by the backup battery  88  is isolated from that powered by the primary battery  84 . Upon pushing the backup push button  16   5 , the backup controller  86  is activated, sending a control signal to the RF transmitter  76  causing the key code to be transmitted by the transmitter through the antenna  78  toward the vehicle V. The RF receiver  98  receives the signal and sends it to backup driver door controller ( 102 ) which in turn unlocks only the front LH latch  92   1 . This will only allow the driver to enter the vehicle and start the vehicle if the power supply ( 100 ) and ECU ( 96 ) are operational and can confirm the key code from the key-fob. 
         [0043]    If the primary power supply or battery  100  of the vehicle V is dead or sufficiently discharged, the BCM/ECU  96  will not operate. However, the backup vehicle access controller  102  will still be powered by the backup battery  104  so that any unlock signal sent by the transmitter  76  of the key will be received by the receiver  98 . The key code will then be confirmed by the backup vehicle entry controller  102  and that controller will send an appropriate signal to the lock actuator  92   1  to unlock the driver door thereby allowing the operator access to the vehicle. This will only allow the driver to enter the vehicle and but NOT start the vehicle. 
         [0044]    In summary, numerous benefits result from employing the vehicle security system  10  disclosed this document. Significantly, a vehicle V is equipped with the electronic security system and any key blade and associated door key lock cylinders and ignition key lock cylinders are omitted. Instead a key blade is provided with a common ignition switch engagement feature  18  which will fit in the ignition switch of all nPEPS vehicles. This commonality reduces production costs of the key fob  14  and allows the manufacturer to use a single key fob body designed for both PEPS and nPEPS vehicles. 
         [0045]    It should be appreciated that these benefits are achieved without compromising vehicle security. This is because a matching electronic key code must be confirmed before the vehicle will grant entry or the ignition will operate. Still further, the backup systems  26 ,  72  of the key and  58 ,  102  of the vehicle ensure that the door lock actuators  46   1 ,  92   1  may be operated under substantially any conditions to allow access to the vehicle. It should also be appreciated that the strength of the signal transmitted by the key transmitter  32 ,  76  may be monitored by the BCM  50 ,  96 . If the signal is weaker than a predetermined level, the BCM  50 ,  96  will provide notice to the vehicle operator to charge or change the battery in the key  12  through a display module (not shown) in the vehicle V or via wireless connection by email or text message to the operator&#39;s computer or telephone. Similarly, the BCM  50 ,  96  may monitor the backup power supply  60 ,  104  for the same purpose and provide a similar notice if required. 
         [0046]    The foregoing has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Obvious modifications and variations are possible in light of the above teachings. All such modifications and variations are within the scope of the appended claims when interpreted in accordance with the breadth to which they are fairly, legally and equitably entitled.