JPS5851483B2 - Method and device for detecting decrease in tire internal pressure in a rail vehicle with pneumatic tires - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for detecting a decrease in the internal pressure of a tire in a guide rail vehicle using pneumatic tires as running wheels.

In order to maintain safe driving in this type of vehicle, it is necessary to detect and deal with tire air leaks at an early stage, and the method of detecting the drop in internal pressure in tires is to directly detect it by installing pressure switches etc. on the running wheels themselves. It is known that ground equipment detects a phenomenon that occurs in a tire whose internal pressure has decreased when a vehicle stops or passes over it.

Among the known methods, the ground method requires a detector installed in each tire, so the total number of sensors is far smaller, and it is much more advantageous in terms of equipment costs and maintenance management, but it directly detects the internal pressure of the tire. There is a problem in that it is difficult to increase the sensitivity and accuracy of detection compared to other methods.

The present invention has been made in view of this point, and it is an object of the present invention to provide a tire internal pressure drop detection device that is simple and small in scale and capable of highly accurate detection.

The following phenomena occur when the internal pressure of a tire decreases.

1. Vehicle structures with dual tires. For example, the most common example is 1, which is used on the rear axle of large buses and trucks.
In the case of a structure in which dual tires are mounted on both ends of an axle, an unbalance of tire load occurs between the dual tires on one side.

That is, the tire load on a tire with a reduced internal pressure decreases, and the load on a tire with a normal internal pressure increases, creating a large difference.

2. In the case of a single tire, vertical deflection increases as the internal pressure decreases.

3. In the case of a single tire, the vertical spring constant decreases as the internal pressure decreases.

4. In the case of a single tire, the width deflection increases as the internal pressure decreases.

5. In the case of a single tire, the contact length increases as the internal pressure decreases.

For example, when the internal pressure decreases by 30%, the contact length decreases by approximately 20%.
increase

Various devices have been proposed in the past that utilize any of these phenomena to detect a decrease in tire internal pressure.

For example, Japanese Utility Model Publication No. 47-24802 discloses a device for detecting a decrease in tire internal pressure by detecting an unbalance of the load between each tire in a vehicle having a dual-wheel structure.

However, the principle of this device cannot be applied to single-tire constructions.

Devices that can be applied to vehicles with a single tire structure include Japanese Patent Publication No. 52-45566 and Japanese Patent Application Laid-open No. 50-107.
There is a method disclosed in Publication No. 617, but since all of these methods detect the longitudinal deflection of the tire, that is, the deflection in the vertical direction, it is necessary to reduce the influence of tire tread wear on the measurement results. , it is necessary to make a comparison in a state where the amount of deflection is large, and only a state with a large pressure drop can be detected, resulting in low sensitivity.

In a vehicle with a single tire structure, a method of detecting by utilizing a decrease in the longitudinal spring constant enables highly accurate detection, but requires complicated equipment and has practical problems.

Also, detecting the increase in width deflection caused by a decrease in internal pressure requires measurement of the maximum center of the tire at a distance from the road, which is impossible to carry out with a simple structure, especially while driving. is difficult to measure.

Therefore, the present invention provides a simple detection method and device that can obtain high sensitivity by detecting an increase in ground contact length that occurs with a decrease in internal pressure. Detecting elements that change state when a tire rides on them are placed on the tracks on which all vehicles are constantly operating, such as entry and exit lines at terminal stations and departure lines at terminal stations. This system compares the length of time during which a state change occurs in the detection element, and detects that the comparison value is greater than a predetermined value to detect a decrease in tire internal pressure. can also be detected without any problem.

Unless the vehicle is in a state immediately before stopping, it is thought that the speed of the vehicle passing over the sensing element will hardly change within a short time while it is passing over the sensing element. It can be considered that it is approximately proportional to the length.

In order to avoid inaccurate measurement results, if the length of the detected state change time is extremely short or not extremely long, those measured values should be excluded from the comparison stage. It is desirable to do so.

Further, the vehicle tire internal pressure drop detection device according to the present invention includes:
A detection element that is provided at a position corresponding to each running wheel on a track on which the vehicle is constantly moving and causes a state change when the running wheel rides on it, and a detection element corresponding to each running wheel. and means for generating an output when the length of the state change time exceeds a predetermined value.

As the sensing element, a pressure-sensitive switch element, a strain resistance element, a piezoelectric element, a load cell whose magnetic permeability changes according to changes in pressure, etc. can be used, and the length of the sensitive part of the sensing element is the normal contact length of the tire. is preferably 115 or less.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Figure 1 shows the relationship between the vehicle and the track in a guided track vehicle. It includes guide wheels 4 and 5 that are connected via a steering link mechanism.

A known structure may be adopted for the arrangement of these running wheels and guide wheels, and detailed explanation thereof will be omitted.

The track has running paths 9, 9' on which the running wheels 7, 8 roll, and guide paths 10, 10' on which the guide wheels 4, 5 roll.

Figure 2 shows point-like sensing elements 11, 11' on a running path
This example shows an example in which the sensor is placed in the sensor, and has a sensing section with an effective length l.

The running wheels 1 and 8 rolling on the running paths 9 and 9' are ground contact surfaces 12
, 12' are in contact with the running paths 9, 9', and the ground contact surface 1
2 is that of a running wheel with a normal internal pressure, and its ground contact length is indicated by L. The ground contact surface 12' is that of a running wheel with a reduced internal pressure, and its ground contact length is indicated as L+2δL.

Therefore, the lengths at which the sensing elements 11 and 11' sense grounding are L+7 and L+ll+2δL, respectively.

FIG. 3 shows the linear sensing elements 13, 13'
' This shows an example where the sensing element 13.13' is placed on the
extends over the gold mines of the running paths 9 and 9', but the sensitive length l is relatively short.

In this example, for example, 14, 14' and 15, 15 are shown in FIG.
'The different wheelbase distances B1. It has the advantage that it can be used similarly for different types of vehicles with B2.

In both the examples of FIGS. 2 and 3, the sensitive length l
is desirably as small as possible, and is preferably 115 or less of the ground contact length of the running wheels with normal internal pressure.

FIG. 4 is a block diagram showing the functions of an electric device constituting a part of the detection device according to the present invention.
' is a pressure-sensitive switch that emits an ON signal when the running wheel rides on it, and that signal is a time counter 17.17'
given to.

As the detection element, in addition to a pressure-sensitive switch, a strain resistance element, a piezoelectric element, a load cell whose magnetic permeability changes depending on pressure, etc. may be used.

Counters 17 and 17' start the counters upon receiving the ON signal, continue counting for 0.005 seconds after the signal from element 16 and 16' turns OFF, and if it is turned ON again within 0.005 seconds. Continue counting.

If it is not turned on within 0.005 seconds, the count result is sent to the first calculation section 18.18'.

However, if the total count is less than 0.01 seconds or 0.
If it takes more than 2 seconds, the results will not be sent.

The first calculation units 18, 18' calculate 0.0 from the received count amount.
005 seconds and sends the result to the second calculation unit 19).

The second calculation section 19 calculates the ratio of the count values sent from the first calculation sections 18 and 18'.

The result is sent to the judgment section 20.

The judgment unit 20 is a part that judges the result, and the second calculation unit 19
If the result sent from is below 0.8 or 1/
When it is 0.8 or more, it is determined that the internal pressure is in a decreased state, and the result is sent to the display section 21.

The display section 21 has a function of sending information to a necessary train operation control room or the like.

Setting the data used for determining the results to be 0.01 to 0.2 seconds corresponds to setting the detection range to a traveling speed of 5 to 100 fan/n.

The excessive count of 0,005 seconds in the counters 17 and 17' is intended to enable normal detection even when the sensing section is momentarily interrupted by noise.

A plurality of determination units 20 are provided, and for example, the second determination is 0.
6 or less or I/O, remove data of 6 or more.
By rubbing, the degree of decrease in internal pressure can be determined and displayed in multiple stages.

In the above description, the sensing element is turned on or in an electromotive state when it is grounded, but it is naturally possible to turn it on or into an electromotive state when it is not grounded.

Further, the present invention is applicable not only to the above-mentioned type of guide rail car, but also to
Of course, it can also be effectively used for mole rails and other rail vehicles that use pneumatic tires as running wheels.

As described above, in the present invention, the tire ground contact length of two running wheels arranged in parallel is measured as the passage time of the ground contact part, and the internal pressure of one of the running wheels is determined by comparing the measured values. It is designed to detect the fact that there is an abnormal drop, and allows highly sensitive detection with simple equipment.

[Brief explanation of the drawing]

FIG. 1 is a schematic front view showing the wheel arrangement of a guided track vehicle to which the method and device of the present invention can be applied; FIG. 2 is a plan view showing the relationship between the sensing element provided on the track portion and the running wheel ground contact portion; FIG. 3 is a plan view similar to FIG. 2 showing another example of the sensing element, and FIG. 4 is a block diagram showing the electrical device. 7.8... Running wheel, 9,9'... Running path, 11°11'... Sensing element.

Claims (1)

[Claims] 1. A method for detecting a decrease in tire internal pressure in a tracked vehicle in which two running wheels made of pneumatic tires are arranged in parallel, comprising:
Detecting elements that cause a state change when a tire rides on a track on which the vehicle is constantly running are arranged at positions corresponding to the running wheels, and the length of time during which a state change occurs in the left and right detection elements due to the running of the vehicle is determined. A method of detecting a decrease in tire internal pressure by comparing the values and detecting that the comparison value is greater than a predetermined value. 2. A method for detecting a decrease in tire internal pressure in the method of item 1 above, in which cases where the length of the detected state change time is too short or too long are excluded. 3. A tire internal pressure drop detection device for a track vehicle in which two running wheels made of pneumatic tires are arranged in parallel, the running wheels being provided at positions corresponding to the respective running wheels on the track on which the vehicle is constantly operating. A means for comparing the length of time during which a state change occurs in a detection element that causes a state change when a vehicle rides on it, and a detection element corresponding to each running wheel, and generates an output when the comparison value exceeds a predetermined value. A tire internal pressure drop detection device comprising: means for detecting a decrease in tire internal pressure. 4. The tire internal pressure drop detection device according to item 3, wherein the detection element is a pressure-sensitive switch element. 5. The tire internal pressure drop detection device according to item 3, wherein the detection element is a strain resistance element. 6. The tire internal pressure drop detection device according to item 3, wherein the detection element is a piezoelectric element. 7. In the third item, the tire internal pressure drop detection method is a load cell whose magnetic permeability changes according to the change in internal pressure. A tire internal pressure drop detection device having a sensing section having the following length.