Apparatus for detecting tire inflation pressure

• US 20050242936A1
• Filed: 04/26/2005
• Published: 11/03/2005
• Est. Priority Date: 04/28/2004
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Watabe, Nobuya
• Granted Patent: US 7,388,478 B2
• Time in Patent Office: Days
• US Class Current: 340/442
• CPC Class Codes: B60C 23/0401 characterised by the type of alarm
• CPC Class Codes: B60C 23/0408 transmitting the signals by non-mechanical means from the wheel or tyre to a vehicle body mounted receiver

Abstract

A sensor detects values of inflation pressure of a tire of a vehicle one after another. A controller calculates, from the values of the tire inflation pressure, a deflation rate at which the tire is deflating per unit time. When the deflation rate is higher than a first predetermined value, the controller judges that the tire is suddenly punctuated. When the deflation rate is not higher than the first predetermined value but is higher than a second predetermined value, the controller judges that the tire is deteriorated. When the deflation rate is not higher than the second predetermined value, the controller judges that compressed air is naturally leaked from the tire. An alarm unit gives an alarm indicating punctuation or deterioration of the tire or natural air leaking in response to the judgment of the controller.

Claims

1. A tire inflation pressure detecting apparatus comprising:

a detecting unit that directly detects inflation pressure of a tire and outputs a detection signal indicating the tire inflation pressure;

a deflation judging unit that;

determines a degree of deflation in the tire inflation pressure from the detection signal outputted from the detecting unit,

judges, from the determined degree of deflation, that the tire has deflated because of a first cause, when the degree of deflation is higher than a first predetermined value,

judges, from the determined degree of deflation, that the tire has deflated because of a second cause, when the degree of deflation is not higher than the first predetermined value but is higher than a second predetermined value that is lower than the first predetermined value, and

judges, from the determined degree of deflation, that the tire has deflated because of a third cause, when the degree of deflation is not higher than the second predetermined value; and

an outputting unit that outputs information showing the first cause when the judgment of the deflation judging unit indicates the first cause, outputs information showing the second cause when the judgment of the deflation judging unit indicates the second cause, and outputs information showing the third cause when the judgment of the deflation judging unit indicates the third cause,

wherein, by means of the degrees of deflation, the judgments differentiate among the causes.

2. The apparatus according to claim 1, further comprising:

a transmitter controller that transmits the detection signal outputted from the detecting unit to the deflation judging unit every predetermined interval of time,

wherein the deflation judging unit obtains the tire inflation pressure every reception of the detection signal and determines the degree of deflation from a difference between the tire inflation pressure currently obtained and the tire inflation pressure obtained previously.

3. The apparatus according to claim 1, further comprising a condition setting unit that sets, based on the judgment of the deflation judging unit, a flickering condition which specifies at least one of a lightening period of time, a flickering cycle, a lightening color and a luminous intensity, wherein the outputting unit comprises an alarm lamp which flickers on the flickering condition.

4. The apparatus according to claim 1, further comprising a condition setting unit that sets, based on the judgment of the deflation judging unit, an alarm sound condition which specifies at least one of a tone of sound, a type of voice, a cycle of sound and strength of sound, wherein the outputting unit comprises an alarm buzzer which gives an alarm sound on the alarm sound condition.

5. The apparatus according to claim 1, further comprising a condition setting unit that sets, based on the judgment of the deflation judging unit, a display condition which specifies at least one of contents of a message and a display color of a message, wherein the outputting unit comprises a display which displays an alarm message on the display condition.

6. The apparatus according to claim 1, wherein the deflation judging unit includes a deflation time determining unit that determines, from the deflation rate, a specific time, at which the tire inflation pressure becomes lower than a predetermined threshold value, or a specific period of time from a base time to the specific time, and the outputting unit outputs information showing the specific time or information showing the specific period of time.

7. The apparatus according to claim 1, wherein the first cause determined by the deflation judging unit is sudden punctuation of the tire, the second cause determined by the deflation judging unit is air leaking based on deterioration of the tire, and the third cause determined by the deflation judging unit is natural air leaking based on non-deterioration of the tire.

8. The apparatus according to claim 1, wherein the detecting unit is disposed in an inside of the tire in which air of the tire is compressed.

9. The apparatus according to claim 1, wherein a vehicle has a plurality of tires, respectively, attached to a plurality of wheels, the detecting unit comprises a plurality of sensors each of which is attached to the corresponding wheel, directly detects a value of inflation pressure of the corresponding tire and outputs a detection signal showing a value of the tire inflation pressure, the deflation judging unit calculates, from each of the detection signals outputted from the sensors, a deflation rate at which the corresponding tire is deflating per unit time, and judges, for each of the wheels from the calculated deflation rate, that the corresponding tire has deflated because of the first, second or third cause, and the outputting unit outputs information showing the first, second or third cause in response to the judgment of the deflation judging unit for each of the wheels.

10. The apparatus according to claim 1, wherein the degree of deflation is a deflation rate at which the tire is deflating per unit time.

11. An apparatus comprising:

a detecting unit that directly detects inflation pressure of a tire and outputs a detection signal indicating the tire inflation pressure;

a deflation time determining unit that;

calculates, from the detection signal outputted from the detecting unit, a deflation rate at which the tire is deflating per unit time, and

determines, from the calculated deflation rate, a specific time, at which the tire inflation pressure becomes lower than a predetermined threshold value, or a specific period of time from a base time to the specific time; and

an outputting unit that outputs information showing the specific time or information showing the specific period of time.

12. The apparatus according to claim 11, further comprising:

a transmitter controller that transmits the detection signal outputted from the detecting unit to the deflation time determining unit every predetermined interval of time, and

a storing unit which stores a set of the tire inflation pressure indicated by the detection signal and time data indicating a reception time of the detection signal each time the deflation time determining unit receives the detection signal,

wherein the deflation time determining unit reads out the set currently stored and another set previously stored from the storing unit, calculates a pressure difference between values of the tire inflation pressure of the two sets, calculates a time difference between the reception times of the two sets, and calculates the deflation rate from the pressure difference and the time difference.

13. The apparatus according to claim 11, further comprising:

a transmitter controller that transmits the detection signal, detected by the detecting unit before running of a vehicle with the tire, to the deflation time determining unit.

14. The apparatus according to claim 11, further comprising a condition setting unit that sets, based on the specific time or the specific period of time determined by the deflation judging unit, a display condition which specifies a display color changing with the specific time or the specific period of time, wherein the outputting unit comprises an alarm lamp which is lightened on the display condition.

15. The apparatus according to claim 11, further comprising a condition setting unit that sets, based on the specific period of time determined by the deflation judging unit, a display condition which specifies lightness or darkness of a display color such that the display color is darkened as the specific period of time is decreased, wherein the outputting unit comprises an alarm lamp which is lightened on the display condition.

16. The apparatus according to claim 11, further comprising a condition setting unit that sets, based on the specific time or the specific period of time determined by the deflation judging unit, a display condition which specifies contents of a message indicating the specific time or the specific period of time, wherein the outputting unit comprises a display which displays the message on the display condition.

17. A tire inflation pressure detecting apparatus comprising:

a detecting unit that directly detects inflation pressure of a tire and outputs a detection signal indicating the tire inflation pressure;

a deflation judging unit that;

determines a degree of deflation in the tire inflation pressure from the detection signal outputted from the detecting unit,

judges, from the determined degree of deflation, that the tire has deflated because of a first cause, when the degree of deflation is higher than a first predetermined value, and

judges, from the determined degree of deflation, that the tire has deflated because of a second cause, when the degree of deflation is not higher than the first predetermined value but is higher than a second predetermined value that is lower than the first predetermined value; and

an outputting unit that outputs information showing the first cause when the judgment of the deflation judging unit indicates the first cause, and outputs information showing the second cause when the judgment of the deflation judging unit indicates the second cause,

wherein, by means of the deflation rates, the judgments differentiate between the causes.

18. A tire inflation pressure detecting apparatus comprising:

a detecting unit that directly detects inflation pressure of a tire and outputs a detection signal indicating the tire inflation pressure;

a deflation judging unit that;

determines a degree of deflation in the tire inflation pressure from the detection signal outputted from the detecting unit,

judges, from the determined degree of deflation, that the tire has deflated because of a first cause, when the degree of deflation is not higher than a first predetermined value but is higher than a second predetermined value that is lower than the first predetermined value, and

judges, from the determined degree of deflation, that the tire has deflated because of a second cause, when the degree of deflation is not higher than the second predetermined value; and

an outputting unit that outputs information showing the first cause when the judgment of the receiver controller indicates the first cause, and outputs information showing the second cause when the judgment of the receiver controller indicates the second cause,

wherein, by means of the deflation rates, the judgments differentiate between the causes.

19. A tire inflation pressure detecting apparatus comprising:

a detecting unit that directly detects inflation pressure of a tire and outputs a detection signal indicating the tire inflation pressure;

a deflation judging unit that;

determines a degree of deflation in the tire inflation pressure from the detection signal outputted from the detecting unit,

judges, from the determined degree of deflation, that the tire has deflated because of air leaking based on deterioration of the tire, when the deflation rate is not higher than a first predetermined value but is higher than a second predetermined value that is lower than the first predetermined value; and

an outputting unit that outputs information showing the air leaking based on the deterioration of the tire.

20. A method of detecting tire inflation pressure, the method comprising:

directly detecting inflation pressure of a tire;

outputting a detection signal indicating the tire inflation pressure;

determining, from the detection signal, a degree of deflation in the tire inflation pressure;

judging, from the determined degree of deflation, that the tire has deflated because of air leaking based on deterioration of the tire, when the deflation rate is not higher than a first predetermined value but is higher than a second predetermined value that is lower than the first predetermined value; and

outputting information showing the air leaking based on the deterioration of the tire.