Tire Pressure Monitoring
Tire Pressure Monitoring
Systems
Systems
Informal Document No.20 (53rdGRRF, 3-7 February 2003, Agenda Item 8)
1.
1.
Background
Background
2. System Classification
2. System Classification
3. Direct TPMS
3. Direct TPMS
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1. Typical Example of the Direct Type
1. Typical Example of the Direct Type
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2. New Development of Direct TPMS
2. New Development of Direct TPMS
4. Indirect TPMS
4. Indirect TPMS
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1. Typical Example of the Indirect Type
1. Typical Example of the Indirect Type
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2. Detection Methods of Indirect TPMS
2. Detection Methods of Indirect TPMS
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3. Variety of Indirect TPMS
3. Variety of Indirect TPMS
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4. New Development of Indirect TPMS
4. New Development of Indirect TPMS
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5. Future Development of Indirect TPMS
5. Future Development of Indirect TPMS
5. Summary of System Classification
5. Summary of System Classification
6. Summary
1.
1. Background
Background
1) TPMS of conventional tires recently came into use on vehicles
mainly as a convenience device for drivers.
2) On the other hand, a
FMVSS 138
rule on TPMS was published
on June 5, 2002 and offers manufacturers 2 options:
- Option 1: TPMS to warn within 10 minutes after the inflation pressure
in one or more (up to four) of the vehicle’s tires, becomes
equal to or
less than 25%
below the recommended pressure.
- Option 2: TPMS to warn within 10 minutes after the inflation pressure
in one of the vehicle tires falls to equal or be
less than 30%
below the vehicle manufacturer’s recommended pressure.
3) By
March 1, 2005
reconsideration will be given to establishing the
performance requirement for the period beginning
November 1, 2006
.
4) There is a discussion concerning TPMS also in Europe.
We believe it is helpful to present an understanding of the
TPMS technologies of both
direct type and
indirect types
.
Direct TPMS Indirect TPMS
- High cost
- Sensor batteries have to be changed periodically.
- Using ABS sensors means only a small on-cost.
Detection Accuracy
Convenience Cost
- Depends on tire characteristics.
▲Tire pressure on each wheel can be displayed.
▼Additional sensors needed with snow tires (user’s on-cost)
▼Wheel type is restricted by integrated sensor/valve
2.
2.
System Classification
System Classification
- Absolute pressure measurement - Relative tire pressure - Absolute pressure (estimated) - More accurate method.
Reliability - High reliability because there is
no additional hardware.
▼In some cases, it may be difficult to guarantee the TPMS
performance on all replacement tires
3.
3.
Direct TPMS
Direct TPMS
ECU Warning Lamp Instrument Panel Pressure display Tire Rim Sensor / Transmitter TRANSMITTER Pressure and Temperature Sensors + Signal conditioningBattery Tire Valve
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-1.
1.
Typical Example of the Direct Type
Typical Example of the Direct Type
Direct type: a system using the actual measurement
of tire pressure.
Sensor & Transmitter
4 Antenna System
1 Antenna System
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-2.
2.
New Development of Direct TPMS
New Development of Direct TPMS
Sensor / Transmitter
Antenna
Warning Lamp
Antenna &Receiver / ECU Sensor / Transmitter Warning Lamp
For cost reduction, the number of the antenna is reduced
from 4 to 1.
Receiver / ECU
COST REDUCTION
4.
Warning Lamp
Wheel Speed Sensor Toothed Rotor TPMS Logic
Tire
Instrument Panel Lower Panel
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-1.
1.
Typical Example of the Indirect Type
Typical Example of the Indirect Type
Set Switch
Indirect type: a system using the wheel speed signals
from the ABS.
ABS ECU
Relative detection Only one wheel deflation can be detected.
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-2.
2.
Detection Methods of Indirect TPMS
Detection Methods of Indirect TPMS
α=VFR VRL VFL VRR VRR VFR VRL VFL
Rolling Radius Method
Rolling Radius Method
(Conventional)
(Conventional)
R
R
’
System
A
A Direct DetectDirect Detect
Detection
speed range 1 wheel deflation:15 to 120km/h
1 wheel deflation: 15 to 120km/h Up to 4 wheels deflation: 15 to 100km/h Up to 4 wheels deflation: 0 to 250km/h Deviation of accuracy (approx.) ±10% at best ±10% at best ±5%
Detection Time 2 to 10min 2 to 10min 15sec to 1min
Characteristic Input signal Antenna Air pressure sensor Receiver Wheels
detection In combination Independent Independent
r
r’
Frequency A m pl it u d e of th e w h eel s p eed Pressure goes down ← ←← ←4
4-
-3.
3.
Variety of Indirect TPMS
Variety of Indirect TPMS
Wheel speeds Wheel speeds Tire pressure
r
r’
Rolling radius Rolling radius + Resonance freq
B
B
Indirect Detect Indirect Detect
System Direct DetectDirect Detect
Detection speed range Up to 3 wheels deflation: 15 to 250km/h Up to 4 wheels deflation: 15 to 100km/h Up to 4 wheels deflation: 0 to 250km/h
Detection Time 2 to 5min
Characteristic Input signal Antenna Air Pressure sensor Receiver Wheels
detection Independent Independent
r
r’
Frequency A m pl it u d e of th e w h eel s p eed Pressure goes down ← ←← ←4
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-3.
3.
Variety of Indirect TPMS
Variety of Indirect TPMS
continuedcontinuedWheel speeds +
Stability Control System signals Tire pressure
Rolling radius + Resonance freq
Up to 3 wheels: 15 to 250km/h
2 to 5min In combination Wheel speeds +
Stability Control System signals
r
r’
Rolling radius C C DD Indirect Detect Indirect Detect Deviation of accuracy (approx.) ±10% at worst ±10% at worst ±5% 15sec to 1min.4
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4.
New Development of Indirect TPMS
New Development of Indirect TPMS
using resonance frequency
using resonance frequency
Up to 4 tires with pressure deficiencies can be detected by the resonance frequency method.
Torsion spring constant is reduced with deflation of tire and consequently the resonance frequency drops
1)
1)
Resonance Frequency Method
Resonance Frequency Method
Independent and absolute detection
Even natural leak deflation of any tire(s) can be detected
Frequency A m pl it ude of w h e e l sp eed Standard Pressure Low Pressure
Tire resonance phenomenon might be not measurable in the situations below.
- high speed - low aspect ratio tires
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4.
New Development of Indirect TPMS
New Development of Indirect TPMS
using resonance frequency
using resonance frequency
3)
3)
Concerns
Concerns
2)
2)
Actual vehicle data
Actual vehicle data
Wheel speed signal
time w h eel s pee d 100 200 300
Tire Pressure(kPa)
28 30 32 34 36 38 40 0 0 0 0 10101010 202020203030 403030404040 505050506060 706060707070 Frequency (Hz) 400 400 400 400 300 300 300 300 200 200200 200 100 100 100 100 0 0 0 0 200kPa 100kPa ■ Gain F requ ency ( Hz ) Frequency analysis
<Concern>
It is difficult to judge whether a difference of wheel speed results from low pressure or from slipping under acceleration.
Development
Engine torque information distinguishes low tire pressure from wheel slip caused by acceleration.
<Concern>
It is difficult to judge, whether a difference of wheel speed results from low pressure or is being caused by cornering.
Development
Cornering information used in Stability Control Systems distinguishes low tire pressure from cornering.
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4.
New Developments of Indirect TPMS
New Developments of Indirect TPMS
using additional signals
using additional signals
クルーガー 中央道 2名乗車 40Nm<Te<70Nmのデータ採用 -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 0 600 1200 1800 2400 3000 time(sec) st210 ra160 クルーガー 中央道 2名乗車 トルク選別なし -0.4 -0.2 0.0 0.2 0.4 0.6 0.8 1.0 0 600 1200 1800 2400 3000 time(sec) st210 ra160 No engine torque signal used
Engine torque signal used
By using Stability Control System’s signals, up to 3 deflated tires can be detected. 1)
1) Two Two ‘‘low tireslow tires’’on the same axle on the same axle (Front or Rear)(Front or Rear)
2)
2)Two Two ‘‘low tireslow tires’’on the same side on the same side (Right or Left)(Right or Left)
Ro lli n g r a d iu s ch a n g e Ro lli n g r a d iu s ch a n g e
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5.
Future Development of Indirect TPMS
Future Development of Indirect TPMS
BS POTENZA RE01 CN T-Contact CH95 DL LEMANS LM702 GY EAGLE LS300 ML pilot SPORT OT DIGNEO PL P-ZERO NERO TY TRAMPIO Vimode YH DNA dB
The effective rolling radius is altered as the tire pressure changes. The value of the change depends on vehicle speed, load and tire variation. 1)
1)Tire characteristic for indirect TPMSTire characteristic for indirect TPMS Load=290kg -0.01 -0.009 -0.008 -0.007 -0.006 -0.005 -0.004 -0.003 -0.002 -0.001 0 100 110 120 130 140 150 160 170 180 190 200 210 220 230 Pressure (kPa) R o lli ng radi u s ch ange 30km/h 100km/h
It is possible to make progress in the performance of indirect TPMS by developing in future, the combination of TPMS and tires.
Identification of
Tire
characteristics
Standardization
of tire radius change
Tire Development Tire Development TPMS Logic TPMS Logic Development Development Use of Stability Control Signals Resonance frequency method
To ensure operation with all replacement tires
To ensure operation with all replacement tires
To inform the driver that TPMS and tires are matched
To inform the driver that
TPMS and tires are matched detection accuracy To improve
To improve detection accuracy
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5.
Future Development of Indirect TPMS
Future Development of Indirect TPMS
continuedcontinued2)
2)To improve the performance of indirect TPMS To improve the performance of indirect TPMS
Future
Direct TPMS Indirect TPMS
- High cost
- Sensor batteries have to be changed periodically.
- Using ABS sensors means only a small on-cost.
Detection Accuracy
Convenience Cost
- Depends on tire characteristics.
▲Tire pressure on each wheel can be displayed.
▼Additional sensors needed with snow tires (user’s on-cost)
▼Wheel type is restricted by integrated sensor/valve
5.
5.
Summary of System Classification
Summary of System Classification
- Absolute pressure measurement - Relative tire pressure - Absolute pressure (estimated) - More accurate method.
Reliability - High reliability because there is
no additional hardware.
▼In some cases,it may be difficult to guarantee the TPMS performance on all replacement tires
1)
Both direct and indirect systems are able to contribute to
the real world safety with regard to tire deflation
- Independent wheel detection
- Tire pressure detection level
2)
For
direct TPMS
the cost will become lower in future.
For
indirect TPMS
it is possible to make progress with
the performance in future, by developing TPMS and
tires in combination.
6.