JP2006220632A - Speedometer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for knowing a speed easily, by using a plurality of whistles having pipe length values different from each other. <P>SOLUTION: In the method, a flow of air having a certain speed is brought to flow in the whistles, and indicating the speed is carried out by the sound of the whistles. A device having one or more whistles is mounted on a helmet, thereby enabling a driver to be informed by bringing the whistles to sound at a speed of 30 km/h, 60 km/h or the like for example, enabling issuance of a warning. Furthermore, as a speedometer can be expected to be realized, where the speed of a mobile object having no axle is treated as a spectrum, based on the sound of the whistles and displayed on a digital device. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

The present invention relates to the field of speedometers, for example, the field of speed indication and warning for vehicles, particularly motorcycles and vehicles without axles.

In order to know the speed of the vehicle, it is common to detect the rotation of the axle, but it is rarely used to detect the speed by the flow of air. However, for example, there are many applications such as Japanese Patent Application Laid-Open No. 06-230020 that know the flow of fluid with a laser beam.

Japanese Patent Laid-Open No. 06-230020

It is an object of the present invention to obtain a speed indication / alarm device that does not have a complicated structure of obtaining a speed by rotation from an axle or the like in order to know a rough speed with a relatively simple configuration and method.

The present invention is characterized in that an air flow at a certain speed flows into a whistle and the speed is instructed by the whistle sounding.

FIG. 1 is the best mode for carrying out the present invention. The air collected by the nozzle generates sound at the reed, and the sound is resonated by the resonance tube. For example, if the opening area of a nozzle is determined so that a long resonance tube resonates at a speed of 30 km / h, in order to resonate at a speed of 60 km / h with a short resonance tube, the nozzle has the same shape (with the same pressure). In the case of air inflow), the ratio of the length of the long resonance tube to the short resonance tube is a ratio of about 2: 1. As a result, the long resonance tube emits sound at a speed of 30 km / h, and the short resonance tube emits sound at 60 km / h. Thereby, speeds of 30 km / h and 60 km / h can be known. The speedometer can be installed, for example, on a motorcycle helmet.
Here, an outline of the theory of hydrodynamics and whistle resonance will be explained. First, the nozzle theory, from Bernoulli's theorem,

Assuming that no turbulent flow occurs,

Therefore, the pressure flowing into the whistle can be adjusted according to the cross-sectional ratio of the nozzle. However, when turbulent flow occurs, the shape of the nozzle must be considered. However, it is one of the purposes to know a rough value, for example, when using it for speed indication of a motorcycle, for example, when the wind is blowing from the nozzle to the whistle, the error is Prone to occur. In the present invention, there may be no nozzle.
Next, I will explain the theory of whistle resonance. Here, the fact that the wind flow is divided into two at the singer is considered without consideration. First, the speed of sound is

It is. Here, γ has a coefficient of about 1.4. ρ is the density of air and P is the pressure.
First, in the case of a whistle at the open end, l is the tube length, δ is the open end correction,

It becomes. Also, from the energy conservation law of simple vibration,

Here, focusing on the moving speed V of the medium,

Here, considering the ratio of m = 0 (fundamental vibration) and m = 1 (secondary vibration), if the speed of each medium is V1, V2, and the length of the tube is l1, l2,

When ρ1 · P2 = ρ2 · P1 (constant sound velocity) and l1 + δ1 = l2 + δ2 (constant tube length) in the fundamental vibration and the secondary vibration,

Accordingly, if one whistle vibrates at V1 = 10 km / h, one whistle vibrates at a higher order at V2 = 30 km / h. However, in reality, there is a loss at the singer, so the value is larger than this ratio.
Now, consider the case where the tube lengths l1 and l2 differ between the fundamental vibrations of m = 1, and P / ρ = constant. From (Equation 9)

Here, when there is no opening end correction, δ1 = δ2 = 0 and each whistle sounds at 30 km / h and 60 km / h.

Therefore,

It becomes. That is, the ratio of the respective tube lengths may be 2: 1.
The above is the case of the open end, but the case of the closed end can be considered similarly.

N = 1 and 2, l1 = l2, P / ρ = constant,

Therefore, for example, when V1 = 30 km / h, it can be seen that higher-order vibration occurs at V2 = 60 km / h.
Next, n = 1 is different from 1, l1, l2, and P / ρ = constant,

As δ = 0 and V2 / V1 = 2,

Thus, it can be seen that at 30 km / h and 60 km / h, in order for the whistle of different tube lengths to resonate, the respective tube lengths should be 2: 1.

  From the above, it was found that in the case of fundamental vibration and double vibration, a speed ratio of 1: 3 can be shown at the open end and a speed ratio of 1: 2 can be shown at the closed end. Next, let's examine the generalization of the relationship between speed ratio and pipe length ratio in the case of a speedometer with two whistle. As in (Equation 12) and (Equation 17), both the open end and the closed end are the same expression, so when δ = 0,

The relationship holds. This is illustrated in FIG.

In the speed indicating device characterized in that a plurality of tube lengths have a relationship of several sequences Ln = L0 / n, when the longest tube length resonates at 10 km / h, 10 km / h, 20 km / h, 30 km / h , 40 km / h, and so on. This is obvious from the number 19 of the theory described above.

FIG. 3 shows an embodiment of a 1/2 geometric sequence speedometer. The tube lengths of 1 and 2 have a ratio of 1/2, and the tube lengths of 2 and 3 also have a ratio of 1/2. In general, the nth tube length is

It has become. This is the tube length corresponding to the geometric sequence. If the pipe length is provided according to (Equation 20), the speed can be set to 10 km / h, 20 km / h, 40 km / h, 80 km / h,.

4 (A) and 4 (B) show a single pipe speed indicator. Corresponding to the tube length and nozzle shape, the tube sounds when it exceeds a certain speed. (A) is an example in which a nozzle is provided, (B) is an example in which a guide is provided, and (C) is an example in which sound is produced at the inlet. In addition, if it supplements, the shape of a nozzle can be determined by (Equation 3).

Example 3 is shown in FIG. This is an example in which the best form is installed in a helmet.

It is an example which displays a speed electronically (with an electronic circuit) using a plurality of tube length whistle. A vibration microphone is attached to each tube, and the signal from the vibration microphone is passed through a filter and is processed by a spectrum processing device. The speed is indicated by a 7-segment LED by a speed instruction circuit. indicate.

In Equation 9, when the basic vibrations of m = 1, different flute tube lengths l1 ≠ l2, different pressures P1 ≠ P2, and ρ = constant,

Here, Equation 3, S1 = πr1 × r1, and S2 = r2 × r2 are used. Therefore, from Equation 21, the speed of the whistle that gives the speed instruction is inversely proportional to the tube length and inversely proportional to the diameter of the nozzle opening. An example made with two whistle is shown in FIGS.

An inexpensive speedometer that gives speed instructions with a simple configuration using a whistle has been realized. Moreover, the utility value is high also as a simple speedometer of the vehicle without an axle.

It is a speedometer that knows two 1: 2 speeds with a ratio of tube length of 2: 1 using two whistle. It is explanatory drawing of Bernoulli's theorem. 6 is a graph showing a relationship between a tube length ratio and an indicated speed. It is an example of a geometric progression type speedometer. It is an example of a single pipe speed indicator. It is an example of this invention with which the helmet was mounted | worn. This is an example applied to a digital speedometer. An example of a speedometer according to claims 7 and 8

Claims (8)

A speed indicating device that informs the speed by the sound of running air flowing into the whistle and making a sound. 2. A speed indicator according to claim 1, wherein a nozzle is provided at the air inlet of the speed indicator. The speed instruction apparatus according to claim 1, wherein a plurality of whistles are provided. 4. The speed indicating apparatus according to claim 3, wherein nozzles are provided at air inlets of the plurality of whistle. 4. The speed indicating device according to claim 3, wherein the tube lengths of the plurality of whistle are the longest tube length, and the nth length Ln of L0 is in the relationship of the numerical sequence Ln = L0 / n. Pointing device. 4. The speed instruction apparatus according to claim 3, wherein the tube lengths of the plurality of whistle are in a geometric sequence. 3. The speed indicating device according to claim 2, wherein the diameter of the nozzle of the air inlet is set to a diameter of the nozzle of the air inlet of the whistle indicating the reference speed with respect to the indicated speed. A speed indicating device that determines the direct line of the nozzle mouth of the whistle indicating other speeds in inverse proportion. 5. The speed indicating device according to claim 4, wherein the diameter of the nozzle opening and the length of the whistle are in inverse proportion to the length of the whistle and inversely proportional to the diameter of the nozzle opening. Speed indicator device that determines the length of the whistle tube tube and the diameter of the nozzle opening.

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