Apparatus for regulating the pneumatic pressure of a motor vehicle tire

• US 5,429,166 A
• Filed: 09/14/1993
• Issued: 07/04/1995
• Est. Priority Date: 09/28/1992
• Status: Expired due to Term

• Current Assignee: Fujikura Limited
• Original Assignee: Fujikura Limited
• Inventors: Tanaka, Minoru, Anzai, Hidenobu, Gotoh, Moritaka
• Primary Examiner(s): Ball, Michael W.
• Assistant Examiner(s): Lorin, Francis J.
• Application Number:
  US08/121,303
• Time in Patent Office: 658 Days
• Field of Search: 152/415, 152/416, 152/417, 152/418, 141/4, 141/95, 141/96, 141/38, 141/197, 137/487.5, 137/228, 364/558, 340/442
• US Class Current: 152/415
• CPC Class Codes: B60S 5/046 using electrical or electronical means

Abstract

An apparatus for regulating the pneumatic pressure of a tire according to the invention calculates the pressure difference between the specified pneumatic pressure entered therein through an input section and the actual pneumatic pressure of a tire measured by a pressure sensor and operates its air charging or discharging valve by specifying an extent of openness of the valve and a time for keeping the valve open as a function of the obtained pressure difference. Thereafter, it calculates the rate of change in the pneumatic pressure of the tire from the actual pneumatic pressure of the tire measured for the second time during the valve is kept open and, at the same time, the pressure difference between the specified pneumatic pressure value and the actual pneumatic pressure of the tire measured for the second time. Then, it calculates second time for keeping the valve open by dividing the pressure difference by the rate of change in the pneumatic pressure of the tire and operates its air charging or discharging valve by specifying for the second time the time for keeping the valve open while keeping the extent of openness of the valve same as that for the first time.

Claims

1. An apparatus for regulating the pneumatic pressure of a tire comprising:

a pneumatic pressure source for storing compressed air;

connecting means adapted to open a tire valve of a tire when connected thereto;

input means for entering a specified pneumatic pressure value;

pneumatic pressure measuring means for measuring the pneumatic pressure of the tire;

an air charge valve for allowing or preventing communication between said connecting means and said pneumatic pressure source;

an air discharge valve for allowing or preventing communication between said connecting means and the atmosphere;

valve drive means for controlling said air charge valve and said air discharge valve;

first memory means for storing values for the extent of openness of the valves and the time for keeping the valves open in accordance with respective values of a pressure difference determined between the entered specified pneumatic pressure value and the pneumatic pressure level of the tire measured by said pneumatic pressure measuring means; and

control means for reading at least one of said stored values in said first memory means which corresponds to a determined value of the pressure difference and raising or reducing the pneumatic pressure of the tire by controlling the valve drive means in accordance with said read value;

wherein said valve drive means controls the extent of openness of the valves and the time for keeping the valves open;

said control means comprises;

first pneumatic pressure regulating means for reading from said memory means a value for the extent of openness of the valve and a value for the time for keeping the valve open which correspond to the pressure difference between the specified pneumatic pressure value stored in the memory means by way of said input means and the actual pneumatic pressure of the tire measured by said pneumatic pressure measuring means to control said valve drive means and operate said air charging valve or air discharging valve with said values of the extent of openness of the valve and the time for keeping the valve open;

rate of pressure change calculating means for calculating the rate of change in the pneumatic pressure of the tire in initial stages of operation of said first pneumatic pressure regulating means;

second memory means for storing said value for the extent of openness of the valve and said calculated rate Of change in the pneumatic pressure;

first pressure difference calculating means for calculating the pressure difference between the specified pneumatic pressure value and the actual pneumatic pressure value of the tire measured after the end of the operation of said first pneumatic pressure regulating means;

second pneumatic pressure regulating means for determining the time for keeping the valve open by dividing the pressure difference calculated by said pressure difference calculating means by said calculated rate of change to control said valve drive means and operate said air charging valve or air discharging valve with said stored value for the extent of openness of the valve and said determined value for the time for keeping the valve open;

second pressure difference calculating means for calculating the pressure difference between the specified pneumatic pressure value and the actual pneumatic pressure value of the tire measured after the end of the operation of said second pneumatic pressure regulating means; and

means for terminating the operation of said pneumatic pressure regulating means when the pressure difference calculated by said pressure calculating means comes to zero.

2. An apparatus for regulating the pneumatic pressure of a tire according to claim 1, wherein said memory means stores a single constant value for the extent of openness of the valve and incremental values for the time for keeping the valve open as a function of said pressure difference.

3. An apparatus for regulating the pneumatic pressure of a tire according to claim 1, wherein said memory means stores a single constant value for the time for keeping the valve open and incremental values for the extent of openness of the valve as a function of said pressure difference.

4. An apparatus for regulating the pneumatic pressure of a tire according to claim 1, further comprising:

display means for displaying said specified pneumatic pressure value entered through said input means and said pressure difference.

5. An apparatus for regulating the pneumatic pressure of a tire according to claim 4, wherein said display means comprises:

a digital display section for displaying said specified pneumatic pressure value;

a plurality of display elements arranged in a row for displaying said pressure difference; and

said control means controlling said plurality of display elements so as to flash a selected number of display elements as a function of the calculated pressure difference, said display elements indicating a pressure increase when said air charging valve is controlled by said pneumatic pressure regulating means, and indicating a pressure decrease when said air discharging valve is controlled by said pneumatic pressure regulating means.

6. An apparatus for regulating the pneumatic pressure of a tire according to claim 4, wherein said display means comprises:

a digital display section for displaying said specified pneumatic pressure value;

an analog display section for displaying said pressure difference; and

said control means controlling the analog display section in accordance with said pressure difference.

7. An apparatus for regulating the pneumatic pressure of tire according to claim 1, wherein the tire is one of a plurality of tires of which the pneumatic pressure is regulated, and wherein after a first tire is regulated, for the remaining tires of the plurality of tires said second pneumatic pressure regulating means utilizes the rate of change calculated for the first tire by said rate of pressure change calculating means.

8. An apparatus for, regulating the pneumatic pressure of a tire according to claim 7, wherein said second pneumatic pressure regulating means utilizes the rate of change calculated for the first tire when the first tire is the same as a current tire being regulated.