System for detecting forces exerted onto a tire

• US 6,668,666 B1
• Filed: 03/15/2002
• Issued: 12/30/2003
• Est. Priority Date: 09/15/1999
• Status: Expired due to Fees

• Current Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Original Assignee: Continental Teves AG & Co. OHG (Continental AG)
• Inventors: Fey, Wolfgang, Chen, Ling, Heinz, Micha
• Primary Examiner(s): Lefkowitz, Edward
• Assistant Examiner(s): Ellington, Alandra
• Application Number:
  US10/088,444
• Time in Patent Office: 655 Days
• Field of Search: 731/46, 731/462, 731/463, 731/464, 731/465, 738/623.81, 152/152.1, 152/151, 340/445, 340/446, 340/447
• US Class Current: 73/862.381
• CPC Class Codes: B60C 13/00 Tyre sidewalls; Protecting, decorating, marking, or the like, thereof B60C17/08 takes precedence; tyre shoulders B60C11/01; removable tyre sidewall trim rings B60B7/01
• CPC Class Codes: B60T 2240/03 Tire sensors
• CPC Class Codes: B60T 8/1725 Using tyre sensors, e.g. Sidewall Torsion sensors [SWT] for tyre pressure and temperature detection B60C23/00
• CPC Class Codes: G01B 7/16 for measuring the deformation in a solid, e.g. by resistance strain gauge
• CPC Class Codes: G01D 3/02 with provision for altering or correcting the law of variation
• CPC Class Codes: G01D 5/24476 Signal processing G01D5/2448 - G01D5/24495 take precedence
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control

Abstract

A device with at least two sensors, especially tire sidewall torsion (SWT) sensors for a motor vehicle control system, wherein the sensors are mounted at varying distances from the tire rotational axis on the chassis or wheel suspension in a stationary manner and wherein the sensors interact with at least one encoder mounted on or in the tire wall or with at least one conventional encoder mounted on or in the tire wall and exhibiting poles. The output signals or output information of the sensors are transmitted to the motor vehicle control system after having been evaluated. In order to provide preprocessed or conditioned data records to the signal processing (DSP=digital signal processor), so that the signal processing software needs to carry out fewer calculating operations to correct the errors in the raw data and determine the tire or wheel forces on the basis of the conditioned data, at least one analog and one digital signal conditioning or processing unit is provided between the motor vehicle control system and the sensors.

Claims

1. A system for sensing forces exerted onto a vehicle tire, comprising:

at least two sensors, said sensors mounted at varying distances from the tire'"'"'s rotational axis, wherein said sensors are adapted to interact with at least one encoder associated with the vehicle tire, and to generate output signals,

a signal conditioning unit coupled to said sensor output signals, wherein said signal conditioning unit includes at least one analog signal conditioning unit and one digital signal conditioning unit, and

a motor vehicle control system coupled to an output of said signal conditioning unit, wherein the at least two sensors include at least one sensor responsive to a change in a phase angle—

and include at least one sensor responsive to a change in amplitude.

2. A device as claimed in claim 1, wherein the analog signal conditioning unit includes one analog-to-digital converter.

3. A device as claimed in claim 1, wherein said at least one analog signal conditioning unit includes:

a converter that transforms a sinusoidal alternating current signal into a voltage,

a filter that suppresses the signal interference,

an offset compensation unit that adapts to changes in the signal offset in the output signal in at least one of the at least two sensors,

a trigger circuit that converts the sinusoidal signal into a rectangular signal, and

an amplitude determining unit that detects the peak value of every half-wave.

4. A device as claimed in claim 1, further including an amplitude determining unit with an isolation amplifier that separately amplifies the positive and negative half-wave of at least one of said sensor output signals,

an inverter that reverses the negative half-wave,

a switch triggered by the signal being applied to the output of the trigger circuit, which switches the positive or negative half-wave to the input of an amplitude value detector in correct phase sequence,

a register that retains the value of the amplitude, and

a circuit controlled by the digital signal conditioning or processing for deleting the register.

5. A device as claimed in claim 1, wherein the digital signal conditioning unit includes at least one logic circuit with at least first and second period counters, and wherein said at least two sensors include a first sensor arranged closer to the rotational axis of the tire and a second sensor arranged further away from the rotational axis of the tire, and wherein a sequencing control starts or stops the first and second period.

6. A device as claimed in claim 5, wherein at least one register is associated with the first and second period counters, and wherein the content of the first and second period counter is written into the register whenever a zero crossover occurs in the first or the second period counters.

7. A device as claimed in claim 5, further including interrupt queue handling logic that defines the order in which the data stored in the first and second period counters will be forwarded to the digital signal processing.

8. A device as claimed in claim 1, further including a status register in which status signals are filed.

9. A device as claimed in claim 8, wherein the status register is read by the digital signal conditioning unit following an interrupt request, then a register with the time and a register with an amplitude value are read and a phase shift is determined from these data.

10. A device as claimed in claim 1, wherein a longitudinal or a transversal force experienced by the tire are calculated on the basis of a phase shift, an amplitude or an amplitude change of said sensor output signals from said at least two sensors.