Method for pressure measurement during tire inflation, automatic inflation method, and tire inflation pump

Abstract

In order to solve the problem of discrepancies between inflation pressure and actual tire pressure during the tire inflation process, the present invention discloses a correction method and an inflator that implements this method. This significantly reduces the error between the pressure displayed on the gauge and the actual tire pressure, thereby enabling the functionality for automatic inflation and cessation of inflation for the tire.

Claims

1. A tire inflator, comprising a pressure sensing unit and a control unit; wherein the pressure sensing unit is configured to detect the inflation pressure and transmit the measured pressure value to the control unit; the control unit is configured to receive the measured pressure value and pause the inflator motor n times during the inflation process, where n3, and substitute the measured pressure values from any three of the n times and the pressure value measured just before or just after each pause into the functional relationship equation between the actual tire pressure P and the inflation pressure P.sub.0, P=aP.sub.0.sup.2+bP.sub.0+c, to obtain the coefficients a, b, c, thereby determining the functional relationship equation and calculating the actual tire pressure P at any moment during the inflation process based on this equation.

2. The tire inflator as claimed in claim 1, wherein the pause duration is set to 1 second.

3. The tire inflator as claimed in claim 1, wherein further comprises a display device for showing the actual tire pressure P.

4. The tire inflator as claimed in claim 1, wherein the control unit is configured to stop the inflator when the actual tire pressure P reaches a preset maximum tire pressure.

5. The tire inflator as claimed in claim 1, wherein the pressure sensing unit is positioned on the body of inflator or on the hose connected thereto.

6. A method for detecting pressure during a tire inflation process, characterized by comprising the steps of: detecting the inflation pressure to obtain the measured pressure value; pausing the inflator motor n times during the inflation process, where n3, and substituting the measured pressure values from any three of the n times and the pressure value measured just before or just after each pause into the functional relationship equation between the actual tire pressure P and the inflation pressure P.sub.0, P=aP.sub.0.sup.2+bP.sub.0+c, to obtain the coefficients a, b, c; calculating the actual tire pressure P at any moment during the inflation process based on this equation.

7. The method for detecting pressure during a tire inflation process as described in claim 6, wherein the pause duration is set to 1 second.

8. A method for automatic inflation, characterized by comprising the steps of: detecting the inflation pressure to obtain the measured pressure value; pausing the inflator motor n times during the inflation process, where n3, and substituting the measured pressure values from any three of the n times and the pressure value measured just before or just after each pause into the functional relationship equation between the actual tire pressure P and the inflation pressure P.sub.0, P=aP.sub.0.sup.2+bP.sub.0+c, to obtain the coefficients a, b, c; when the actual tire pressure P reaches the preset maximum tire pressure, stopping the inflator.

9. The method for automatic inflation as described in claim 8, wherein the pause duration is set to 1 second.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic diagram of the pressure gauge placement in a tire inflating process in the prior art.

(2) FIG. 2 is a graph illustrating the relationship between inflation pressure and actual tire pressure during the inflation process in a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) A plurality of preferred embodiments of the present invention are described below with reference to the drawings, which makes its technical content more clear and convenient to understand. The present invention may be embodied in many different forms of embodiments, and the scope of protection of the present invention is not limited to the embodiments set forth herein.

(4) As depicted in FIG. 2, tests have revealed that when inflating a tire, the relationship between the actual tire pressure P and the inflation pressure P.sub.0 follows a quadratic curve. The mathematical expression of this relationship can be formulated as:

(5) $P=a{P}_0^2+{\mathrm{bP}}_0+c$

(6) For a quadratic function curve, at least three points' coordinates are needed to determine its coefficients a, b, and c, thus establishing the function. Since the pressure measured when the air pump stops inflating is consistent with the actual tire pressure, we can measure the actual tire pressure by pausing the inflation momentarily during the process. As shown in FIG. 2, the vertical axis represents the actual tire pressure P, and the horizontal axis represents the inflation pressure P.sub.0. In this embodiment, inflation is paused for about 1 second at three points P.sub.01, P.sub.02, and P.sub.03. The pressure measured after stopping the inflation is the actual pressure at each point, P.sub.1, P.sub.2, and P.sub.3, while the measured pressure at the moment just before pausing or just as inflation resumes is the measured pressure at that point, P.sub.0. In FIG. 2, the measured pressures and actual pressures at the three points are shown in Table 1.

(7) TABLE-US-00001 TABLE 1 Pausing Inflation Actual Tire Point Pressure(psi) Pressure(psi) 01 37.7 10 02 40.8 20 03 46 30

(8) Substituting the values of the aforementioned three points into Equation (1), we can obtain the coefficients a=0.0151, b=3.3387, and c=93.829 for the actual tire pressure P and the measured pressure P.sub.0 in the functional relationship Equation. The functional relationship is then given by:

(9) $P=-0.0151.Math.P_0^2+3.3387.Math.P_0-93.829$

(10) The function curve is illustrated by the dashed line in FIG. 2. From this, we can calculate the actual tire pressure at any given moment based on the measured pressure, and use the actual pressure to replace the measured pressure for display or to further control the inflation process based on this.

(11) In practice, the size of different tires and varying lengths of the hose can affect the calculated values of the coefficients a, b, and c in the functional relationship formula. This is because the internal volume of the tire, the resistance of the hose, and the pressure drop across the valve core can all influence the relationship between the measured inflation pressure and the actual tire pressure. Therefore, it may be necessary to calibrate the system for different tire sizes and hose lengths to ensure accurate pressure readings and proper inflation control.

(12) Of course, in other embodiments, the parameters of the function relationship formula can also be further amended through multiple pauses to make them more accurate. In practical use, by adjusting the time interval between each short stop, the error between the measured pressure and the tire's true pressure can be controlled within 2 psi, which means the maximum deviation does not exceed 5% of the actual tire pressure. This approach allows for a more precise inflation process, ensuring that the tire is inflated to the desired pressure level with minimal margin of error.

(13) To implement this method, the inflator according to the present invention should at least have a pressure sensing device and a control unit. The pressure sensing device can be set up externally on the tire, just like in the prior art, such as on the inflator itself. The pressure sensing device transmits the pressure signal to the control unit. The control unit can employ programmable control devices such as a Microcontroller Unit (MCU) or a Programmable Logic Controller (PLC). The control unit receives the pressure signal from the pressure sensing device and controls the start and stops of the air pump motor through a relay, for instance, according to the aforementioned method, and computes the real-time pressure. The inflator according to the present invention generally also includes display devices such as numerical display equipment to show the real-time computed pressure. Additionally, since the present invention can significantly reduce the error between the computed pressure and the actual pressure, the control unit can also set a maximum inflation pressure. This allows the inflator to automatically stop inflating when the tire pressure reaches the maximum pressure, providing a more accurate and safe inflation process.

(14) The foregoing detailed description describes preferred embodiments of the invention. It should be understood that many modifications and variations can be made in accordance with the concepts of the present invention without creative efforts by those of ordinary skill in the art. Accordingly, all the modifications and alterations of the device and method made by those skilled in the art without departing from the spirit shall be deemed as still within the scope of the invention as defined by the appended claims.