U.S. patent application number 09/730958 was filed with the patent office on 2002-06-06 for tire pressure vehicle speed limiting.
This patent application is currently assigned to Lear Corporation. Invention is credited to Ghabra, Riad, Khreizat, Salman, Nantz, John S., Tang, Qingfeng.
Application Number | 20020069008 09/730958 |
Document ID | / |
Family ID | 24937485 |
Filed Date | 2002-06-06 |
United States Patent
Application |
20020069008 |
Kind Code |
A1 |
Nantz, John S. ; et
al. |
June 6, 2002 |
TIRE PRESSURE VEHICLE SPEED LIMITING
Abstract
Tire over- or under-inflation can create problems in vehicle
operation. To limit the effects of out-of-range tire pressure,
vehicle speed is automatically controlled if the vehicle speed is
not appropriate for measured tire air pressure.
Inventors: |
Nantz, John S.; (Brighton,
MI) ; Ghabra, Riad; (Dearborn Heights, MI) ;
Tang, Qingfeng; (Novi, MI) ; Khreizat, Salman;
(Dearborn, MI) |
Correspondence
Address: |
Mark D. Chuey
Brooks & Kushman P.C.
1000 Town Center, Twenty-Second Floor
Southfield
MI
48075
US
|
Assignee: |
Lear Corporation
21557 Telegraph Road
Southfield
MI
48034
|
Family ID: |
24937485 |
Appl. No.: |
09/730958 |
Filed: |
December 5, 2000 |
Current U.S.
Class: |
701/93 ;
701/79 |
Current CPC
Class: |
B60W 2530/20 20130101;
B60T 8/172 20130101; B60W 2050/021 20130101; B60W 30/146 20130101;
B60K 31/00 20130101; B60W 2710/0616 20130101 |
Class at
Publication: |
701/93 ;
701/79 |
International
Class: |
G06F 007/00 |
Claims
What is claimed is:
1. A method of limiting vehicle speed comprising: sensing the air
pressure in at least one tire; sensing vehicle speed; determining
if the vehicle speed is appropriate for each tire based on the
sensed tire air pressure; and automatically controlling vehicle
speed if the vehicle speed is not appropriate for each tire.
2. A method of limiting vehicle speed as in claim 1 wherein
reducing vehicle speed comprises controlling the delivery of fuel
to an engine powering the vehicle.
3. A method of limiting vehicle speed as in claim 1 wherein
reducing vehicle speed comprises controlling the delivery of spark
to an engine powering the vehicle.
4. A method of limiting vehicle speed as in claim 1 wherein
reducing vehicle speed comprises controlling the delivery of air to
an engine powering the vehicle.
5. A method of limiting vehicle speed as in claim 1 wherein
reducing vehicle speed comprises controlling the revolution rate of
a rotating power plant powering the vehicle.
6. A method of limiting vehicle speed as in claim 1 wherein
reducing vehicle speed comprises controlling the delivery of
electrical power to a motor powering the vehicle.
7. A method of limiting vehicle speed as in claim 1 wherein the
vehicle speed is appropriate for the tire if the tire pressure is
greater than a minimum value.
8. A method of limiting vehicle speed as in claim 1 wherein the
vehicle speed is appropriate for the tire if the tire pressure is
greater than a value based on the vehicle speed.
9. A method of limiting vehicle speed as in claim 1 wherein the
vehicle speed is appropriate for the tire if the tire pressure is
less than a maximum value.
10. A method of limiting vehicle speed as in claim 1 wherein the
vehicle speed is appropriate for the tire if the tire pressure is
less than a value based on the vehicle speed.
11. A method of limiting vehicle speed as in claim 1 further
comprising indicating automatic speed reduction to a vehicle
operator.
12. A system for limiting vehicle speed comprising: at least one
tire pressure sensor generating a pressure signal based on the
pressure of air within a tire; a vehicle speed sensor generating a
signal based on vehicle speed; a power plant causing the vehicle to
move at the vehicle speed based on power plant control signals; and
control logic in communication with each tire pressure sensor, the
vehicle speed sensor and the power plant, the control logic
generating at least one power plant control signal to automatically
control vehicle speed if the vehicle speed is not appropriate for
at least one tire based on the sensed tire air pressure.
13. A system for limiting vehicle speed as in claim 12 further
comprising an indicator controlled by the control logic, the
indicator indicating automatic speed reduction to a vehicle
operator.
14. A system for limiting vehicle speed as in claim 12 wherein the
control logic automatically reduces vehicle speed if the tire
pressure is less than a minimum value.
15. A system for limiting vehicle speed as in claim 12 wherein the
control logic automatically reduces vehicle speed if the tire
pressure is less than a value based on the vehicle speed.
16. A system for limiting vehicle speed as in claim 12 wherein the
control logic automatically reduces vehicle speed if the tire
pressure is greater than a maximum value.
17. A system for limiting vehicle speed as in claim 12 wherein the
control logic automatically reduces vehicle speed if the tire
pressure is greater than a value based on the vehicle speed.
18. A system for limiting vehicle speed as in claim 12 wherein each
tire pressure sensor generates a signal based on self diagnosis,
the control logic inhibiting automatic vehicle speed reduction
based on sensed tire air pressure for a tire with a pressure sensor
generating a failed self diagnosis signal.
19. A system for limiting vehicle speed as in claim 18 further
comprising an indicator controlled by the control logic, the
indicator indicating the tire pressure sensor failed diagnostic
testing.
Description
TECHNICAL FIELD
[0001] The present invention relates to measuring vehicle tire air
pressure and utilizing these measurements.
BACKGROUND ART
[0002] The air pressure within inflated vehicle tires is an
important parameter for vehicle operation. Vehicle dynamics are
closely linked to tire performance. These dynamics affect many
aspects of vehicle operation, including handling, braking, rollover
characteristics, and the like. Tire pressure also affects the life
of the tire. Excess tire pressure may make the tire more
susceptible to puncture and, if extreme, to burst damage. Tire
under-pressure may result in the generation of excess heat,
particularly at elevated vehicle speeds. To ensure proper tire
performance, vehicle tires are typically given a range of inflation
pressures based on the tire type, vehicle type, vehicle
configuration and use, expected driving conditions, and the like.
Despite its importance, tire inflation pressure may at times fall
outside of specified ranges. Tires often lose air pressure
gradually, making the point at which inflation pressure drops below
the specified value difficult to detect. Many air pressure gauges
for use with vehicle tires are inaccurate, resulting in
under-inflation or over-inflation even when proper care is taken.
Further, modern run-flat tires provide limited performance even in
the presence of substantial pressure loss, making such loss
difficult for the vehicle operator to detect.
[0003] In-vehicle tire pressure monitoring systems are currently
available. Typically, these systems include a tire pressure sensor
built into the tire or attached to the tire valve stem. Each sensor
relays measured tire pressure to an associated receiver via a
wireless link. Tire pressure information is then provided to the
vehicle operator by an indicator or graphic display on the vehicle
dashboard. Such a display, however, may not solve the problem of
out-of-range tire pressure if the display is either unnoticed,
misinterpreted, or ignored by the vehicle operator. What is needed
is to automatically reduce the effects of out-of-range vehicle tire
pressure.
DISCLOSURE OF INVENTION
[0004] The present invention automatically controls vehicle speed
if the vehicle speed is not appropriate for measured tire air
pressure.
[0005] A system for limiting vehicle speed is provided. The system
includes at least one tire pressure sensor. Each tire pressure
sensor generates a pressure signal based on the pressure of air
within a tire. The system also includes a vehicle speed sensor
generating a signal based on the vehicle speed. Control logic
generates at least one signal to control the vehicle power plant
automatically reducing vehicle speed if that speed is not
appropriate for at least one tire based on the sensed tire air
pressure.
[0006] In an embodiment of the present invention, the system
further includes an indicator controlled by the control logic. The
indicator indicates automatic speed reduction to the vehicle
operator.
[0007] In another embodiment of the present invention, each tire
pressure sensor generates a signal based on self diagnosis. The
control logic inhibits automatic vehicle speed reduction based on
sensed tire air pressure in a tire with a pressure sensor
generating a failed self diagnosis signal.
[0008] In various additional embodiments of the present invention,
the control logic automatically reduces vehicle speed if the tire
pressure is less than a minimum value, if the tire pressure is less
than a value based on the vehicle speed, if the tire pressure is
greater than a maximum value, and/or if the tire pressure is
greater than a value based on the vehicle speed.
[0009] A method of limiting vehicle speed is also provided. Air
pressure is sensed in at least one tire. The vehicle speed is
sensed. A check is made to determine if vehicle speed is
appropriate for each tire based on the sensed tire pressure. If
vehicle speed is not appropriate for each tire, the vehicle speed
is automatically controlled.
[0010] In various embodiments of the present invention, the vehicle
speed may be reduced by controlling the delivery of fuel to an
engine powering the vehicle, controlling the delivery of spark to
an engine powering the vehicle, controlling the delivery of air to
an engine powering the vehicle, controlling the revolution rate of
a rotating power plant powering the vehicle, and controlling the
delivery of electrical power to a motor powering the vehicle.
[0011] These and other objects, features and advantages of the
invention are readily apparent from the following detailed
description of the best mode for carrying out the invention when
taken in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a block diagram of a system for limiting vehicle
speed based on tire pressure according to an embodiment of the
present invention; and
[0013] FIG. 2 is a flow diagram of a method for limiting vehicle
speed based on tire pressure according to an embodiment of the
present invention.
BEST MODE FOR CARRYING OUT THE INVENTION
[0014] Referring to FIG. 1, a block diagram of a system for
limiting vehicle speed based on tire pressure according to an
embodiment of the present invention is shown. Wheeled vehicle 20
has one or more tires 22, at least one of which is typically driven
by power plant 24 to propel vehicle 20 at a particular vehicle
speed. Any form of power plant 24 may be used, including gasoline
engines, turbines, diesel engines, electric motors, and the like.
Power plant 24 receives power plant control signals 26 from power
plant controller 28. Power plant controller 28 controls the
operation of power plant 24 by receiving inputs from a variety of
sensors such as speed sensor 30 measuring the speed of vehicle 20.
Power plant control signals 26 modify the operation of power plant
24 through a variety of means depending, in part, on the type of
power plant 24. These include controlling the delivery of fuel,
spark, and air to an engine powering vehicle 20; controlling the
revolution rate of a rotating power plant 24 powering vehicle 20;
and controlling the delivery of electrical power to a motor
powering vehicle 20. Thus, power plant 24, controller 28, and speed
sensor 30 form a closed loop system that may be used to control the
speed of vehicle 20.
[0015] At least one tire 22, and preferably each tire 22, are
monitored for tire inflation pressure by tire pressure sensors 32.
Typically, tire pressure sensor 32 is located within tire 22 or is
attached to an inflation valve for tire 22. Tire pressure sensor 32
measures the air pressure within tire 22. Tire pressure sensor 32
or an associated sensor may also measure one or more additional
parameters associated with tire 22, such as tire temperature, tire
usage, tire life, and the like. A preferred tire pressure sensor 32
is the model SP13 from SensoNor asa of Norton, Norway.
[0016] Information is transmitted from tire pressure sensor 32
through wireless link 34 to one or more receivers 36. Wireless link
34 is preferably a radio link, but may be established through any
wireless means including ultrasonic, subsonic, magnetic coupling,
and the like. Each tire 22 may have an associated receiver 36 or
receiver 36 may be located in a central position within vehicle 20.
Receiver 36 forwards tire pressure information to, or is
incorporated into, tire pressure monitor 38.
[0017] Tire pressure monitor 38 may perform a variety of functions.
Tire pressure monitor 38 calculates the pressure in each tire 22
based on signals from receivers 36. Tire pressure monitor 38 may
calculate the pressure in each tire 22 based on information from
other sensors, such as ambient pressure sensor 40, ambient
temperature sensor 42, and the like. Tire pressure monitor 38 may
also display information about the pressure in each tire 22 on
display 44 viewable by an operator of vehicle 20.
[0018] Together, power plant controller 28 and tire pressure
monitor 38 comprise control logic generating power plant control
signals 26 to automatically control the speed of vehicle 20 if the
vehicle speed is not appropriate for at least one tire 22 based on
the sensed tire air pressure. Vehicle speed control may include
reducing vehicle speed and preventing vehicle speed from exceeding
a limiting speed. The limiting speed may be a preset value or may
be calculated based on vehicle operating conditions. As will be
recognized by one of ordinary skill in the art, controller 28 and
tire pressure monitor 38 may be incorporated into the same device
or may be divided between two or more devices. Control logic 46 may
also be distributed to one or more receivers 36 and intelligent
tire sensors 32. Preferably, control logic 46 is implemented as one
or more microcontrollers. Some or all of control logic 46 may also
be implemented using discrete components, programmable logic
devices, gate arrays, custom integrated circuit chips, and the
like.
[0019] Preferably, control logic 46 provides notification to an
operator of vehicle 20 when speed is limited or reduced. This
notification may be accomplished through an indicator lamp or
illuminated graphic, through an image and/or text displayed on a
screen, through an audio warning, through a heads-up display, or
the like. Any such notification is represented generally by display
44.
[0020] Control logic 46 may also suspend automatic speed reduction
based on the pressure in a tire 22 sent by tire pressure sensor 32
with a fault or other detected problem. Tire pressure sensor 32 may
perform self diagnostic tests such as transducer failure, low
battery, circuitry failure, and the like. Tire pressure sensor 32
may generate a signal indicating a failed self diagnostic test.
Control logic 46 may then warn the vehicle operator through display
44 and ignore any subsequent out-of-range signal from tire pressure
sensor 32 until a passing self diagnosis signal is received from
tire pressure sensor 32 or until control logic 46 is reset, such as
after replacing tire pressure sensor 32.
[0021] Referring now to FIG. 2, a flow diagram of a method for
limiting vehicle speed based on tire pressure according to an
embodiment of the present invention is shown. As will be
appreciated by one of ordinary skill in the art, the operations
illustrated in the flow diagram are not necessarily sequential
operations. The order of steps may be modified within the spirit
and scope of the present invention. Also, the method illustrated in
FIG. 2 may be implemented by any combination of hardware, software,
firmware, and the like. The present invention transcends any
particular implementation and the embodiment is shown in sequential
flow chart form for ease of illustration.
[0022] Tire pressures are determined in block 50. Tire pressures
are based on measurements taken by tire pressure sensors 32. These
measurements may be corrected for sensor characteristics, such as
non-linearity and drift, and may be compensated for sensor
cross-sensitivities such as temperature. Additional factors, such
as ambient temperature, ambient pressure, tire loading, and the
like, may be taken into account to improve measurement accuracy.
Tire pressure calculation may take place in one or more of tire
pressure sensor 32, receiver 36, tire pressure monitor 38, or
controller 28.
[0023] Vehicle speed is determined in block 52. Speed sensor 30
measures the speed of vehicle 20. A wide variety of devices,
methods, and locations for measuring the speed of vehicle 20 are
known in the art. The actual vehicle speed or a value representing
vehicle speed may be calculated from information supplied by speed
sensor 30 in either or both of controller 28 and tire pressure
monitor 38. The speed of vehicle 20 is typically displayed on
display 44.
[0024] A check is made to determine if vehicle speed is appropriate
for tire pressures in block 54. One or more of several comparisons
may be used to determine if the speed of vehicle 20 is appropriate.
First, vehicle speed may not be appropriate if the pressure in one
or more tires 22 is less than a minimum value. This minimum value
may be a preset threshold or may be based on one or more operating
conditions of vehicle 20 such as vehicle load and load
distribution, four-wheel drive mode, towing mode, automatic
suspension mode, traction control operation, automatic brake system
control, tire location, air pressure in other tires, ambient air
pressure, ambient temperature, and the like. Second, vehicle speed
may not be appropriate if one or more tires 22 have a tire pressure
less than a value based on the speed of vehicle 20. Third, vehicle
speed may not be appropriate if one or more tires 22 have a tire
pressure greater than a maximum value. As with the minimum value,
the maximum value may be preset or may be based on one or more
vehicle operating conditions. Fourth, vehicle speed may not be
appropriate if one or more tires 22 have a tire pressure greater
than a value based on the vehicle speed. If vehicle speed is
appropriate for tire pressures, the process of determining tire
pressures and vehicle speed is repeated.
[0025] If vehicle speed is not appropriate for one or more tire
pressures, the vehicle speed is reduced in block 56. The speed of
vehicle 20 may be reduced to a value that is preset or based on one
or more vehicle operating conditions. The maximum allowable speed
may also be a function of the pressure in one or more tires 22.
Preferably, controller 28 reduces the speed of vehicle 20 gradually
until the speed of vehicle 20 is appropriate for the pressure in
tires 22. Controller 28 reduces the speed of vehicle 20 by
generating power plant control signals 26 to control one or more
parameters of power plant 24. Preferably, the vehicle operator is
warned if vehicle speed is reduced due to measured tire pressure.
The process of determining tire pressures and vehicle speed is then
repeated.
[0026] While embodiments of the invention have been illustrated and
described, it is not intended that these embodiments illustrate and
describe all possible forms of the invention. Rather, the words
used in the specification are words of description rather than
limitation, and it is understood that various changes may be made
without departing from the spirit and scope of the invention.
* * * * *