Tire-pressure control apparatus

• US 7,882,733 B2
• Filed: 09/06/2007
• Issued: 02/08/2011
• Est. Priority Date: 12/28/2006
• Status: Expired due to Fees

• Current Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Isono, Hiroshi
• Primary Examiner(s): Allen; Andre J
• Application Number:
  US12/092,410
• Publication Number:
  US 20100170605A1
• Time in Patent Office: 1,251 Days
• Field of Search: None
• US Class Current: 73/146.8
• CPC Class Codes: B60C 23/004 the control being done on the wheel, e.g. using a wheel-mounted reservoir
• CPC Class Codes: B60C 23/127 the pumps being mounted on the hubs
• CPC Class Codes: B60C 23/137 comprising cam driven pistons

Abstract

A tire-pressure control apparatus includes an air pump driven by a rotating wheel to supply compressed air to a tire air chamber, a mechanical control valve that permits and prohibits supply of compressed air from the air pump to the tire air chamber, a valve-state detection sensor that detects the state of the control valve, a wheel speed sensor that detects rotational speed of the wheel, and an electric control unit (ECU). The ECU calculates a quantity of compressed air supplied from the air pump to the tire air chamber during a permission-state retention time, during which the control valve is in the permission state, and calculates an average leaked air quantity per unit time in a single cycle starting when the control valve enters a prohibition state and ending when the control valve again enters the prohibition state after entering the permission state.

Claims

1. A tire-pressure control apparatus comprising:

an air pump which is driven by a rotating wheel so as to supply compressed air to a tire air chamber of the wheel;

a mechanical control valve device disposed in an air passageway extending between the air pump and the tire air chamber and adapted to control a tire pressure within the tire air chamber, the control valve device being in a permission state where the control valve device permits supply of compressed air from the air pump to the tire air chamber during a period over which the tire pressure increases to an upper limit set value from a lower limit set value after having decreased to the lower limit set value, and being in a prohibition state where the control valve device prohibits supply of compressed air from the air pump to the tire air chamber during a period over which the tire pressure decreases to the lower limit set value from the upper limit set value after having increased to the upper limit set value;

a valve state detection sensor for detecting whether the control valve device is in the permission state or the prohibition state;

time measurement means for measuring a prohibition-state retention time, which is a time period starting when the control valve device enters the prohibition state and ending when the control valve device enters the permission state and a permission-state retention time, which is a time period starting when the control valve device enters the permission state and ending when the control valve device enters the prohibition state;

a wheel speed sensor for detecting rotational speed of the wheel;

total-discharged-air-quantity calculation means for calculating a total discharged air quantity, which is a total quantity of compressed air supplied from the air pump to the tire air chamber during the permission-state retention time, from a previously obtained quantity of compressed air discharged from the air pump per single revolution thereof and the rotational speed of the wheel which the wheel speed sensor detects during the permission-state retention time measured by the time measurement means; and

average-leaked-air-quantity calculation means for calculating an average leaked air quantity per unit time in a single cycle starting when the control valve device enters the prohibition state and ending when the control valve device again enters the prohibition state after entering the permission state or a single cycle starting when the control valve device enters the permission state and ending when the control valve device again enters the permission state after entering the prohibition state, from the prohibition-state retention time and the permission-state retention time measured by the time measurement means and the total discharged air quantity calculated by the total-discharged-air-quantity calculation means.

3. A tire-pressure control apparatus according to claim 1, further comprising:

leakage-quantity determination means for determining whether or not the average leaked air quantity is greater than a set value; and

reporting means for reporting results of determination by the leakage-quantity determination means.

2. A tire-pressure control apparatus comprising:

an air pump which is driven by a rotating wheel so as to supply compressed air to a tire air chamber of the wheel;

a mechanical control valve device disposed in an air passageway extending between the air pump and the tire air chamber and adapted to control a tire pressure within the tire air chamber, the control valve device being in a permission state where the control valve device permits supply of compressed air from the air pump to the tire air chamber during a period over which the tire pressure increases to an upper limit set value from a lower limit set value after having decreased to the lower limit set value, and being in a prohibition state where the control valve device prohibits supply of compressed air from the air pump to the tire air chamber during a period over which the tire pressure decreases to the lower limit set value from the upper limit set value after having increased to the upper limit set value;

a valve state detection sensor for detecting whether the control valve device is in the permission state or the prohibition state;

time measurement means for measuring a prohibition-state retention time, which is a time period starting when the control valve device enters the prohibition state and ending when the control valve device enters the permission state and a permission-state retention time, which is a time period starting when the control valve device enters the permission state and ending when the control valve device enters the prohibition state;

a wheel speed sensor for detecting rotational speed of the wheel;

average-discharged-air-quantity calculation means for calculating an average discharged air quantity, which is a quantity of compressed air supplied from the air pump to the tire air chamber per unit time during the permission-state retention time, from a previously obtained quantity of compressed air discharged from the air pump per single revolution thereof and the rotational speed of the wheel which the wheel speed sensor detects during the permission-state retention time measured by the time measurement means; and

average-leaked-air-quantity calculation means for calculating an average leaked air quantity per unit time from the average discharged air quantity calculated by the average- discharged-air-quantity calculation means and a ratio of the permission-state retention time to a time of a single cycle starting when the control valve device enters the prohibition state and ending when the control valve device again enters the prohibition state after entering the permission state or a single cycle starting when the control valve device enters the permission state and ending when the control valve device again enters the permission state after entering the prohibition state.

4. A tire-pressure control apparatus according to claim 2, further comprising:

leakage-quantity determination means for determining whether or not the average leaked air quantity is greater than a set value; and

reporting means for reporting results of determination by the leakage-quantity determination means.