Antitheft device for vehicles

Details Antitheft device for vehicles Antitheft device for vehicles

2000-10-20

2003-02-04

Pope, Daryl (Department: 2632)

Communications: electrical

Land vehicle alarms or indicators

C340S426110, C340S427000, C307S010200, C307S010300, C429S007000

Reexamination Certificate

active

06515580

ABSTRACT:

BACKGROUND OF THE INVENTION
This invention relates to an antitheft device for vehicles and more particularly to an improved antitheft device that avoids bypassing or disabling of the antitheft system and which offers a lower cost.
Conventionally, vehicles employ in addition to electronic ignition controls, other ECU operated devices that function to provide antitheft protection. These are generally utilized in conjunction with a special key that has a sending unit that sends an identification code to a unit on the vehicle so that the vehicle can confirm that a licensed or authorized user is attempting to start or operate the vehicle. Although these systems have a high degree of utility, the antitheft system normally uses a control unit or ECU that is separate from the ECU of the ignition system for the vehicle. Thus, there are external connections between the two units. When an external connection is employed, this gives rise to the possibility of a person being able to defeat the antitheft system. In addition it increases the overall cost.
This type of problem can be best understood by reference to
FIGS. 1
,
2
and
3
which show antitheft systems of the prior art types that are employed with vehicles such as a small vehicle like a motor scooter or motorcycle.
FIG. 1
is a side elevational view of a small vehicle of the type with which the prior art type of antitheft unit has been employed and which is, in the illustrated example, a motor scooter, indicated generally by the reference numeral
11
. The motor scooter
11
includes a body frame assembly
12
that rotatably journals a rear wheel
13
and a dirigible front wheel
14
, the latter of which is controlled by a handle bar assembly
15
. A rider sits on a seat
16
and controls the vehicle from this location.
The vehicle includes a powering internal combustion engine, indicated generally by the reference numeral
17
and which is of the spark ignited type that includes an ignition coil
18
which is controlled by a CDI ignition control unit
19
that includes an ECU that operates on any type of known strategy. The CDI ignition control unit is enclosed within the body frame assembly to improve security.
The unit includes a main switch
21
that is switched by a suitably coded key with the coding being interrelated to an antitheft unit
22
, in a manner, which will be described shortly, for controlling the operation of the vehicle
11
. The main switch
21
includes an antenna that receives signals from a transponder carried on the key so as to determine if an authorized user is operating the vehicle or not. Alternately the antenna may be mounted elsewhere on the vehicle, preferably enclosed by the body frame assembly
12
for security reasons. An indicator
24
may be mounted on the handle bar assembly
15
so as to be viewed by the operator seated on the seat
16
. This shows the antitheft status.
The vehicle also includes a battery
25
that provides electrical power including power for the starting of the engine
17
by means of a starter motor
26
under the operation of the main switch
21
.
An alarm
27
is also associated to provide an audible warning under certain conditions as well as a tilt sensor
28
that determines if the vehicle is being moved without an authorized user.
The units shown in
FIG. 1
are those, as has been previously noted, of a conventional system and this conventional system generally falls into one of two categories. The first of these categories is shown schematically in
FIG. 2
that constitutes a schematic electrical diagram. In this diagram, only the non-grounded terminal of the battery P and its connections to the various components are illustrated. The main switch
21
is positioned in a line L
2
that has connection both to the ignition control unit
19
at R
1
and via the line L
3
and a connection via a connector Q
2
to the antitheft unit
22
. Thus, when the main switch
21
is closed, both the antitheft unit
22
and ignition unit
19
are enabled. A further line L
1
continuously connects the battery
25
and its terminal T to the antitheft unit through a direct connection Q
1
.
A line from the main line L
2
and controlled by the main switch
21
contains a normally open solenoid operated switch
29
which is energized when the antitheft unit
22
determines that a registered user is using the vehicle, in a manner which will be described, and permits energization of the starter motor
26
to provide starting. The ignition unit
19
then supplies electrical power to the coil
18
and an associated spark plug
31
of the engine
17
for permitting its operation.
The antenna
23
will receive a signal from an owner identification device such as a key
32
, which has a transponder that outputs a coded signal to the antitheft unit
22
through a connector Q
3
. As long as the antitheft unit
22
determines that there is an appropriate user, then the antitheft
22
actuates the solenoid switch
29
through a connection Q
7
to the line L
2
and the engine can be started and operated.
If, on the other hand, there is an attempt to steal the vehicle either by the use of improper key or by the determination by the tilt sensor
28
that the vehicle
11
is being moved by other than an authorized user, then the antitheft unit
22
receives a signal at the terminal Q
4
and disables the starter motor
26
by opening the solenoid switch
29
. Also, the alarm
27
is sounded and it may be a sound and/or flashing of the turn signals or other units of the vehicle
11
. In addition, the antitheft unit
22
outputs a signal to a display or indicator
24
so as to confirm that the operation is either normal antitheft operation or a condition exists where a theft of the vehicle is being attempted. The method by which the attempted theft is determined can be of any suitable type.
The problem with this type of system is that because the antitheft unit
22
and ignition unit
19
are separate, they have a number of external connections between them, which this permits a person to bypass the antitheft unit
22
. For example, a thief may bypass the relay operated switch
29
by using a jumper cable L
5
(shown in phantom) between the terminals to the starter motor
26
and the terminal Q
2
and line L
2
downstream of the main switch
21
. Then, the vehicle can be operated without permission and can be stolen.
FIG. 3
shows another prior art type of antitheft unit, which also has the disadvantages of failing to provide adequate antitheft protection due to the use of the separate antitheft unit
22
and ignition control unit
19
and associated external terminals. It also has the added cost of requiring two, separate CPUs.
In this construction, the components are basically the same as and thus have been identified by the same reference numerals as applied in FIG.
2
. In this arrangement, the main switch
21
is again placed in the line L
2
but in this instance, the line L
2
is connected only to the antitheft unit
22
through an external terminal Q
1
. This unit includes an internal switch
41
, which connects the electrical power from the line L
2
to a terminal R
1
of the ignition control unit
19
via an external conductor L
5
.
When the proper key is utilized, the switch
41
is closed and then the ignition unit is enabled so that the engine
17
can be operated. In this unit, a line L
4
goes directly from the line L
2
downstream of the main switch
21
to the starter motor
26
so that the starter motor will be energized when the main switch is operated. However if the proper, authorized key is not utilized the engine
17
will not start because the spark plug
31
will not be fired.
With this type of unit, if a theft is detected in any of the known manners including those previously mentioned, the theft alarm
27
is enabled and the ignition control unit is switched off by opening the switch
41
. Thus, theft is prevented.
However, again because of the use of the external terminals, a thief can put a jumper line L
6
(shown in phantom) between the battery terminal P and the conductor R

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