JPH06219114A - Tire internal pressure detector - Google Patents

Abstract

PURPOSE:To enable monitoring or continuous measurement of tire internal pressure safely at low cost without placing a device in a part to rotate at high speed and without increasing weight by using a wheel rotating speed sensor or the like being an existing brake device in order to detect the tire internal pressure of a levitation type railway rolling stock where there exists even a case such as traveling at the highest speed when a mechanical brake is used. CONSTITUTION:Informations (omega) from respective wheel rotating speed sensors of four wheels of a single bogie are compared with each other, and internal pressure is detected from an increase in the (omega) caused by a decrease in a rolling radius of the wheels whose internal pressure is decreased. A wheel rolling radius is found by operation on V/omega by this and information V from vehicle speed, and the individual wheels of not more than a control limiting rolling radius 7 are judged as a decrease in the internal pressure. The internal pressure is also estimated as a continuous quantity from the relationship between bending of a tire and the internal pressure under the load condition after an uneven load of a vehicle by combining the rolling radius and information of a load gauge 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting the internal pressure of a pneumatic tire during rotation.

[0002]

2. Description of the Related Art Conventionally, pneumatic tire internal pressure detection devices have been put to practical use in some new transportation systems, automobiles, and aircraft. The measuring unit uses a mechanical pressure switch with a diaphragm that does not require electric power.It has a single function that only indicates the tire internal pressure drop condition outside the tire. There are various types such as a system that detects as a continuous quantity, corrects it according to the ambient temperature, and then displays and warns at a remote location.

In many of these methods, a method of directly converting the internal pressure of the tire into a mechanical display of pressure or a measuring instrument of the type of converting into an electric signal is adopted. One of the typical methods of extracting the pressure as a signal is a device (pressure signal converter 62) for converting the pressure, which is a physical quantity of gas, into a signal and outputting it directly to the outer peripheral portion 61 of the wheel as shown in FIG. It is a method of processing and mounting, and installing so that the sensor part is directly exposed to the gas inside the tire.

Since these pressure-related signals are generated on the side of the wheel 2, signal transmission from the rotating portion to the stationary portion is necessary for signal transmission to the signal processing portion 64 mounted on the vehicle body. The signal from the pressure signal converter 62 is applied to the wheel outer peripheral portion 6
Radio transmission is performed by the ring-shaped antenna 63 installed in No. 1 and reception is performed by the fixed antenna 68 on the vehicle body side, thereby transmitting from the rotating portion to the stationary portion by a non-contact transmission method. The fixed antenna 68 and the ring-shaped antenna 63 are also used to supply necessary electric power from the signal processing unit 64 to the electronic circuit of the pressure signal converter 62.

The vibration acceleration applied to the pressure signal converter as the vehicle travels is large in both frequency and absolute value because it is directly transmitted from the road surface without intervention of the spring / damping system, and centrifugal force due to wheel rotation is also added. Large mechanical disturbance.
This becomes more remarkable as the turning radius of the wheel increases and the rotating speed increases, but it depends on the wheel traveling speed and the outer diameter of the wheel in the existing new transportation system and the tire internal pressure detection device of the automobile or the aircraft. To some extent, they have fundamental problems that are unavoidable in terms of mechanical strength, safety, and reliability. It is a design constraint that is incompatible with the design requirements for system simplification and weight reduction.

Specifically, in consideration of the pressure signal converter 62 having sufficient mechanical strength to withstand centrifugal force, an increase in weight is inevitable. Placing the pressure signal converter 62 on the wheel outer peripheral portion 61 intensively adds the mass to a portion having a large radius of rotation, and changes the inertial ratio of the equal distribution with respect to the center of rotation, which adversely affects the rotational movement. It will increase the weight such as wearing the counter balance weight 65 so as not to give.

As a method of avoiding this, in order to reduce the inertial mass as shown in FIG. 7, the pressure signal converter 62 having a large mass and its counterbalance weight 65 are arranged on the wheel axle portion 66 having a small turning radius, and the tire is rotated. The air conduit 7 is formed by using an air outlet formed by processing the inner pressure itself to the wheel outer peripheral portion 61 or a valve (filling valve 67) for filling the tire with air or nitrogen gas from the outside.
1, the pressure signal converter 62 installed on the wheel axle 66
It is a method of converting to a signal.

However, even with this method, the mass other than the tire 1 is added to the wheel 2 rotating at high speed, and the air conduit 71 must be attached to the wheel 2 so as not to be deformed or dropped by centrifugal force. However, it is necessary to take measures against centrifugal force and vibration, which will increase the weight. On the contrary, if the air conduit 71 is damaged due to a collision with a flying object or the like, there is a risk of causing a secondary disaster such as a decrease in tire internal pressure.

Further, in particular, when the existing system is used for the levitation type railway, the wheels of the levitation type railway have a stationary magnetic field of about 3000 gauss and a fluctuating magnetic field of about ± 50 gauss generated by a superconducting magnet mounted in the vicinity thereof. Because it is placed inside, it seems that it is used in new transportation systems, cars and aircraft,
In the case of the ring-shaped antenna 63, which is installed on the wheel outer circumference 61 as shown in FIG. 6 in order to transfer the electric signal from the rotating wheel to the stationary portion, in the case of the levitation railway, electromagnetic noise is superimposed on the correct pressure signal. However, the electric signal indicating the tire internal pressure cannot be accurately transmitted.

As a remedy for this, as shown in FIG. 7, the induction coil 72 is arranged in close proximity to and facing each other, and electromagnetic induction stronger than the electromagnetic noise of the environment is generated in the induction coil 72 to transmit and receive signals. There is a way.

However, even with this method, since the pressure signal converter 62 containing the electronic component is mounted on the side of the wheel 2 which is constantly exposed to high vibration acceleration, there remain problems in reliability and mechanical fatigue. Furthermore, if an abnormality occurs in the electric brake system, which is the basic brake system of the levitation railway, the disc brakes attached to the wheels (not shown) are 500 km / h.
When it is operated from the above, the environmental temperature of the axle part rises to nearly 200 ° C. due to the thermal energy converted from the kinetic energy, and the same temperature condition is caused by the heat generated by the use of the disc brake that is commonly used in aircraft. Considering the heat insulation and heat resistance design so that the pressure signal converter 62 with built-in electronic components can withstand this, the electronic circuit becomes complicated and inevitably increases in volume and weight.

[0012]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a wheel that is a high-speed rotating portion for directly measuring pressure in order to detect a decrease in internal pressure of a tire. It is to obtain the tire internal pressure indirectly from other measurement information without attaching a measurement sensor.

[0013]

In order to achieve the above-mentioned object, the tire internal pressure detection device of the present invention has a wheel rotation speed for anti-lock brake control for preventing lock of a wheel brake already mounted on a vehicle. It is possible to judge the decrease of the tire internal pressure only from the wheel rotation speed from the sensor, or to calculate the wheel rolling radius by combining the information of the wheel rotation speed and the vehicle running speed to judge the decrease of the tire internal pressure. By adding the information of wheel load data to the vehicle traveling speed information, not only the presence or absence of the decrease in the tire internal pressure is determined, but also the numerical value of the tire internal pressure is continuously estimated. The purpose of detecting the tire internal pressure is to add software that calculates from the existing measurement information, without adding new hardware, resulting in no weight increase at all,
It was realized without the need to transfer information from the rotating part to the stationary part and without compromising reliability.

[0014]

First Embodiment FIG. 1 shows a cross-sectional view of a floating railroad vehicle wheel assembly as one embodiment of the present invention. The circumscribing auxiliary wheel 4 supports the vehicle vertical load when the tire 1 is punctured, and the circumscribing auxiliary wheel radius dimension 6 is Rs. The radius dimension Rs of the circumscribing auxiliary wheel 4 with some allowance is set to Ra, and the radius limit R is determined to be a control limit radius dimension 7 for determining that the tire is in a state of flexure and decrease in internal pressure. Rb is the tire rolling radius dimension 8 when a regular wheel load is applied with a regular tire internal pressure. Ro is the tire radius dimension 10 when no load is applied to the wheel. The output of the wheel rotation speed sensor 5 for controlling the anti-lock brake is constantly output during traveling of the wheels for the purpose of controlling the braking force of the disc brake (not shown) or for confirming the normal rotation of the wheels.

In the case of FIG. 1, an example of an optical rotation speed pulse generator built in a hollow axle 3 of the same type as an aircraft is shown, but information uniquely correlated to the rotation speed can be obtained from the rotating portion. Any method of locating the wheel rotation speed sensor may be used as long as it does not require data transmission to the stationary portion. For example, a speed generator may be used.

Assuming that the outputs of the four wheel rotation speed sensors of the first to fourth support wheels on one bogie of the levitation railway vehicle are ω ₁ to ω ₄ , these signals are compared and the variation is Rb. It is determined that the internal pressure of the tire mounted on the wheel that has become equal to or higher than the value of / Ra has decreased to the control value or higher.
Even if the wheel with the decreased tire internal pressure is under the same load condition,
This is because the amount of deflection increases, the wheel rolling radius decreases, and the vehicle rotation speed ω increases relatively compared to the wheel rotation speeds of other normal internal pressure tires, as shown in Fig. Directly proportional. For example, Rb is 300 mm and Ra is 2
If it is set to 70 mm, a wheel having a variation of more than 10% is determined as a wheel in which the tire internal pressure has decreased to a control value or more, with 10% as a threshold value.

FIG. 2 shows an output example in the case where the wheel disc brake operation is performed with the vertical axis representing the output data of the wheel rotation speed sensor and the horizontal axis representing the time under the above conditions. The wheel rotation speed 21 of the wheel whose internal pressure has decreased appears higher than the wheel rotation speed 23 of the normal wheel. When this speed difference is 10% or more, it is determined that the internal pressure has dropped to a control value or more. Generally, the wheel rotation speed sensor for anti-lock brake control has good signal decomposition performance, and when the wheel is locked due to the operation of the anti-lock brake control mechanism in the brake operating state, brake release is automatically performed, and wheel rotation The raw signal of the speed sensor output may have a spiked signal. In that case, a signal calculation process such as filtering or integration is performed, or the wheel reference speed calculated from the calculation function of the antilock brake control mechanism is compared to determine the reference speed of the wheel whose internal pressure has decreased. The information after being processed to the reference speed 24 is used.

During normal running other than the wheel disc brake operation, no spike-like signal is generated in the output of the wheel rotation speed sensor, and the signals of the wheel with the lowered internal pressure and the normal wheel are respectively the reference speed 22. And 24.

According to this method, the decrease in tire internal pressure can be detected with a threshold value equal to or more than a certain variation value of the wheel rotation speed, based on the minimum information of the wheel rotation speed which is constantly monitored. The method of the first embodiment can be directly applied to a new transportation system, an automobile, or an aircraft by adding a function of comparing rotation speeds to a system that constantly measures the rotation speeds of individual wheels.

[0020]

[Embodiment 2] The levitation railway of the primary linear propulsion system on the ground always travels while detecting the speed Vv of the vehicle by the cross guidance radio installed on the ground for propulsion and braking of the vehicle.
The information is always wirelessly transmitted to the vehicle, and the vehicle also employs a multiplex system in which the velocity Vv is detected independently from the ground, although the description is omitted. It is shown in the second embodiment that the vehicle speed information of any one of them is used at a minimum.

When the angular velocity ω is taken as the wheel rotational velocity and the tangential velocity is V, the turning radius R is given by R = V / ω. The rolling radius R of the wheel is estimated by this calculation. When this value is equal to or less than the control limit radius Ra as shown in FIG. 1, it is determined that the tire internal pressure has dropped to a control value or more due to excessive bending.

For the angular velocity ω, the signal of the wheel rotation velocity sensor is processed by the anti-lock brake control device to obtain the reference velocity information having no spike waveform. On the other hand, when the wheel brake is actuated, the wheel slips relative to the track, and strictly speaking, the tangential speed V of the wheel rotation does not match the vehicle traveling speed Vv. In order to calculate the tangential speed V as accurately as possible, the speed Vv of the vehicle is corrected and used based on the slip ratio information of the antilock brake control device. The high-speed anti-lock brake system has a function to correct the slip ratio as standard, but if it does not exist, it is necessary to add a radius calculation function and a slip ratio correction function. The block diagram is shown in FIG.

However, when the tire internal pressure is low or the wheel load is small, it is not always possible to detect the internal pressure in detail by this method. If the vehicle travels in a curved section with a cant at a speed other than the set speed, the centrifugal force and the gradient component of the gravitational acceleration due to the cant angle will not balance, and the load will be biased to the right two wheels or the left two wheels out of the four wheels on one bogie. It will be. Further, the load is biased to the two rear wheels during acceleration and to the two front wheels during deceleration due to the longitudinal acceleration. This is because it is not possible to determine whether the wheel rolling radius R is decreased due to an increase in tire flexure caused by such a load deviation of the wheels or the rolling radius is decreased due to a decrease in the tire internal pressure itself.

However, for the following reason, as shown in FIG.
High-pressure and high-load tires, such as aircraft tires and levitation railway vehicle tires, are more sensitive to internal pressure fluctuations than tire load fluctuations. If it is a simple method of judging that the tire internal pressure has dropped below the control value, the change of the tire rolling radius due to the load change is in the dead zone and there is no practical problem.

In FIG. 4, the vertical axis represents the tire deflection amount (the tire rolling radius R is obtained by subtracting the deflection amount from the radius Ro of the tire when there is no load, that is, D = Ro-R), and the horizontal axis represents the wheel load. The relationship between the tire flexion amount change due to the wheel load change at a constant tire internal pressure will be shown with the tire internal pressure as a parameter. The tire rolling radius R changes due to independent changes in both the wheel load L and the tire internal pressure P, but if the tire internal pressure is constant, the tire deflection amount can be approximated to be proportional to the first power of the load.

The tire internal pressure of a car is 2 kgf / cm for passenger cars.
About ^2, 7 kgf / cm ² approximately in large trucks, at 9 kgf / cm ² about the new transportation system, the internal pressure of a tire of a floating rail vehicle is about 21 kgf / cm ² before and after use tires high internal pressure of the aircraft par is doing. Furthermore, even with the burden load per tire, the levitation railway has a maximum of 9 tons, and the levitation railway tire has a high load at about 4 to 10 times that of an automobile.

As a result, as shown in FIG. 4, the tire used for the aircraft and the levitation railway vehicle is obtained from the tire deflection amount DL with respect to the maximum load deviation that can be predicted by the movement and posture of the vehicle under the condition of the normal internal pressure. Also, the tire deflection DP corresponding to the rolling radius Ra is larger under normal load conditions, and the wheel rolling radius does not change to the deflection DP unless it is caused by a decrease in internal pressure. There is no problem in determining the decrease in tire internal pressure.

For example, in a tire with the maximum load and standard internal pressure of the current design of a levitation type rail vehicle, the load fluctuation until the tire is below the limit radius Ra for judging that the tire is flexed and the internal pressure is reduced is about 6 t, Kant section stop and maximum acceleration,
Even if the maximum deceleration by emergency braking is taken into consideration, such a load bias does not occur. Conversely speaking, the bending of the tire to the control limit radius Ra does not occur except for the decrease of the internal pressure. Therefore,
The second embodiment can be adopted as a simple method of issuing an alarm using the control limit radius Ra that is determined as the internal pressure reduction state as a threshold value. The vehicle speed information Vv may be transmitted on the vehicle by a signal of the cross guidance radio or may be obtained by an independent method on the vehicle.

Since this calculation can be carried out independently for each supporting wheel, it is possible to deal with the internal pressure drop of a plurality of wheels of the four legs in the same carriage at the same time, and it is possible to make an independent judgment for each wheel. Become. This system can be applied to new transportation systems, automobiles, and aircraft as long as the system uses tires whose flexure is more sensitive to internal pressure fluctuations than load fluctuations.

[0030]

Third Embodiment This embodiment is a method of estimating the tire internal pressure as a continuous numerical value. Tire rolling radius R is tire internal pressure P
It is applied to be proportional to. Although FIG. 4 shows that the tire rolling radius R is proportional to the first power of the wheel load L, the tire rolling radius R is also proportional to the tire internal pressure P at the same time. This is clearly shown in FIG. The tire deflection amount D is plotted on the vertical axis of the same tire data as in FIG. 4, the tire internal pressure P is plotted on the horizontal axis, and the wheel load L is used as a parameter. To show how it changes. The curve of the tire deflection amount with respect to the tire internal pressure is represented by the wheel load L.

In particular, in the range where the tire internal pressure is within ± 20% of the specified internal pressure, the slope of the curve is expressed by a linear expression of the tire internal pressure P, that is, ΔD / ΔP = aP + b. Also, the intersection C with the vertical axis is C = cP + d, which is proportional to the first power of the tire internal pressure. Therefore, the tire deflection amount D can be accurately approximated by Formula 1. Here, a, b, c and d are constants.

[Equation 1] When Formula 1 is converted into a formula relating to P, Formula 2 is obtained.

[Equation 2] The information on the wheel load L is constantly output for monitoring and controlling the running condition of the supporting legs of the floating railway vehicle at low speed, and therefore, it is obtained from the load gauge 9 installed on the axle as shown in FIG. . If the wheel load L is known, Equation 2 is 1 of D
It is the following equation, and the deflection amount D is D = corresponding to the wheel rolling radius R.
It can be obtained from Ro-R and the tire internal pressure P can be approximated by a simple linear equation. Using this relationship, the tire internal pressure P can be correctly estimated even under an arbitrary wheel load condition.

[0032] While the ± 20% of said as linear equation with respect to the scope approximation prescribed internal pressure, the tire pressure detection range by represented by Formula higher order curve of Figure 8 in P ⁿ following equation approximation N need not be an integer, as it can be easily widened. That is, the conversion formula for calculating the internal pressure in the calculation unit is
It may be expressed by an equation that can approximate a detection width as wide as necessary with P = f (D, L). In this method, the internal pressure is uniquely determined from the tire deflection amount and the tire load.

FIG. 5 shows a block diagram of the third embodiment. Strictly speaking, the temperature of the gas filled in the tire influences, and there are some conventional tire internal pressure detection devices such as automobiles that use the signal of the temperature sensor to correct the tire internal pressure, but in the case of a levitation railway, wheel traveling It is a short time with limited time, and its influence can be ignored in normal driving. In implementing the present invention, a temperature correction function may be added if necessary.

[0034]

As described above, in the tire internal pressure detection device of the present invention, all the constituent elements for monitoring and measuring the decrease in the tire internal pressure of the wheel that rotates at high speed are in the non-rotating portion, and the existing signal is used. Since the calculation is performed, there is an advantage that the reliability is high, it is safe because it does not become a new secondary disaster source even if it breaks down, and the weight increase can be prevented. In addition, the wheel does not require any processing. In the existing tire internal pressure detection device, at least one pressure signal converter is installed on the wheel, and a plurality of pressure signal converters are installed on the wheel to improve reliability. There is no increase and it can be realized at low cost. As a simple specification, it can be used as an alarm device for a decrease in internal pressure, and by also using the signal from the wheel load sensor, it can be applied to continuously measure the tire internal pressure.

[Brief description of drawings]

FIG. 1 is a sectional view of a floating railroad vehicle wheel assembly showing an embodiment of the present invention.

[Fig. 2] Example of output data of a rotation speed sensor when a wheel disc brake is activated

FIG. 3 is a block diagram in the case of judging by a wheel rolling radius.

FIG. 4 is a diagram in which a relationship between a tire load and a flexure amount is expressed by using an internal pressure as a parameter.

FIG. 5 is a block diagram when determination is made based on wheel rolling radius and wheel load.

FIG. 6 is an assembled sectional view of a conventional tire internal pressure detection device.

FIG. 7 is an assembly sectional view of a conventional tire internal pressure detection device in consideration of measures against centrifugal force.

FIG. 8 is a diagram in which the relationship between the tire internal pressure and the amount of flexure is expressed by using a load as a parameter.

[Explanation of symbols]

 1. Tire 2. Wheel 3. Axle 4. External contact auxiliary wheel 5. Wheel speed sensor 6. Circumscribing auxiliary wheel radius 7. Control limit radius dimension 8. Tire rolling radius when a normal load is applied 9. Load gauge 10. 21. Tire radial dimension when no load is applied 21. 22. Wheel rotation speed of the wheel with reduced internal pressure Reference speed of wheels with reduced internal pressure 23. Wheel rotation speed of normal wheel 24. Normal wheel reference speed 61. Wheel outer periphery 62. Pressure signal converter 63. Ring-shaped antenna 64. Signal processing unit 65. Counter balance weight 66. Wheel axle 67. Fill valve 68. Fixed antenna on vehicle body 71. Air conduit 72. Induction coil

Claims (3)

[Claims] 1. In a tire internal pressure detecting device, means for measuring the wheel rotation speed of each wheel in place of the means for directly measuring the pressure in order to detect a decrease in the internal pressure of a pneumatic tire; A tire internal pressure detection device comprising: a means for comparing the measured value of the means with a control value; and a means for issuing an alarm of a decrease in the tire internal pressure according to the comparison output of the comparison means. 2. In a tire internal pressure detecting device, a means for measuring a vehicle speed and a wheel rotation speed of each wheel in place of a means for directly measuring a pressure for detecting a decrease in internal pressure of a pneumatic tire, The difference between the means for calculating the tire rolling radius from the measurement value of the measuring means and the tire rolling radius when there is no wheel load at the normal internal pressure is the deflection amount, and the result of the calculating means is predetermined. When the tire flexure amount or more, the means for determining that the tire internal pressure has decreased to a value to be controlled or less, and means for issuing a warning of a decrease in the tire internal pressure according to the determination result of the determination means. Tire pressure detector 3. A tire internal pressure detection device detects a decrease in internal pressure of a pneumatic tire even when a wheel load deviates from a stationary or cruising running to a curved running or acceleration / deceleration at each wheel. Therefore, instead of directly measuring the pressure, means for measuring the vehicle speed and the wheel rotation speed of each wheel, means for calculating the tire rolling radius from the measurement value of the measuring means, and each wheel By installing a means for measuring the vertical load, it is possible to continuously detect the numerical value of the tire internal pressure from the relationship between the tire internal pressure change and the tire deflection amount change in the case of wheel load under each unbalanced load condition. Tire internal pressure detection device characterized in that it is possible