KR101472550B1

KR101472550B1 - Method for manufacturing piezo sensor

Info

Publication number: KR101472550B1
Application number: KR20140073094A
Authority: KR
Inventors: 조성윤
Original assignee: (주)노바코스
Priority date: 2014-06-16
Filing date: 2014-06-16
Publication date: 2014-12-16
Also published as: WO2015194811A1

Abstract

Disclosed are a piezo sensor and a piezo sensor manufacturing method. The piezo sensor manufacturing method, by which the piezo sensor buried in a road detects pressure by a car traveling on the road, acquires traveling information of the car is manufactured, includes: (a) a step to spirally wind a first piezo film in a longitudinal direction around a surface of a conductive body, wherein the first piezo film is wound to be partially superimposed; (b) a step to pass the conductive body around which the first piezo film is wound through a roller such that the conductive body has a vertically pressed flat shape; (c) a step to insert the flattened conductive body around which the first piezo film is wound into a metallic tube; and (d) a step to pass the metallic tube into which the conductive body is inserted through a roller such that the metallic tube has a vertically pressed flat shape.

Description

METHOD FOR MANUFACTURING PIEZO SENSOR [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a piezo sensor and a manufacturing method thereof, and more particularly, to a piezo sensor capable of measuring a traffic volume and the like using a pressure of a vehicle and a manufacturing method thereof.

As the number of vehicles increases with industrial development, the sensors are installed on the roads for the purpose of determining the number of vehicles passing through the roads and controlling the overloaded vehicles. Piezo sensors are sensors mounted on the road that sense the pressure of the car as it passes.

The prior art of the present invention is Korean Patent Laid-Open Publication No. 2011-0001837 (Piezoelectric Sensor Module).

The present invention provides a piezo sensor having high durability and high reliability and a method of manufacturing the same.

According to an aspect of the present invention, there is provided a method of manufacturing a piezo sensor embedded in a road to detect pressure by an automobile passing on the road to obtain traffic information of the automobile, the method comprising: (a) Winding the first piezoelectric film in a spiral manner; B) passing the conductor wound with the first piezo film through a roller to form the conductor into a flat shape pressed up and down; (c) inserting the conductor into which the first piezoelectric film wound in a flat shape is wound, into a metal tube; And (d) passing the metal tube into which the conductor is inserted through a roller, thereby making the metal tube into a flat shape in which the metal tube is pushed up and down.

Before the step (c), the method may further include pressing the metal tube having a circular cross section in advance up and down in advance.

The method may further include, before the step (b), winding the second piezo film on the first piezo film in a direction symmetrical to the first piezo film with respect to the longitudinal axis.

According to another aspect of the present invention, there is provided a piezo sensor embedded in a road to detect pressure by an automobile passing on the road to obtain traffic information of the automobile, the sensor comprising: a sensor unit for converting the pressure into an electrical signal; And a cable electrically connected to the sensor unit and transmitting an electric signal generated by the sensor unit. At this time, the sensor unit includes a conductor; A first piezoelectric film wound and surrounded in a spiral shape along the longitudinal direction of the conductor so that a part thereof is superimposed; And a metal tube surrounding the first piezo film to prevent damage to the conductor and the first piezo film. The sensor unit has a flat shape that is pushed up and down so that the left and right widths are larger than the upper and lower depths.

The first piezoelectric film may further include a second piezoelectric film wound on the first piezoelectric film in a direction symmetrical to the first piezoelectric film with respect to the longitudinal axis.

In addition, the first piezoelectric film may be a film in which one side has a corrugated shape and the other side has a straight line.

Also, the cable may be a bipolar wire including a first polarity line and a second polarity line, the first polarity line being in contact with the conductor, and the second polar line being in contact with the metal tube.

A shrink cover for sealing the connection between the cable and the metal tube; A protective tube surrounding the outer surface of the shrink cover and injecting a filler into the shrink cover; And an outer tube covering the outer side of the protective tube.

According to a preferred embodiment of the present invention, the reliability of the measurement can be improved while enhancing the durability of the piezo sensor.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a state diagram showing a state in which a piezoelectric sensor according to an embodiment of the present invention is used. FIG.
2 is a perspective view illustrating a piezo sensor according to an embodiment of the present invention;
3 is a flow diagram illustrating a method of manufacturing a piezo sensor in accordance with an embodiment of the present invention.
4 is a view showing a state in which a first piezo film is wound on a surface of a conductor.
5 is a cross-sectional view showing a state in which a first piezo film is wound on a surface of a conductor.
6 is a view showing a state in which a second piezo film is wound;
7 is a view showing a state in which a piezo-electric film is wound with a conductor by a roller;
8 is a cross-sectional view showing a pre-pressurized metal tube;
9 is a view showing a state where a conductor inserted in a metal tube is pressed by a roller.
10 is a sectional view showing a sensor unit according to an embodiment of the present invention;
11 is a view showing a state where a sensor unit and a cable are connected.
12 is a view showing a state where a portion to which a sensor unit and a cable are connected is covered by a shrink tube.
13 is a view showing a state in which a shrink tube is covered by a protective tube;
14 is a view showing a state in which the protective tube is covered by the outer tube;
15 is a photograph showing a piezo sensor according to an embodiment of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention is capable of various modifications and various embodiments, and specific embodiments are illustrated in the drawings and described in detail in the detailed description. It is to be understood, however, that the invention is not to be limited to the specific embodiments, but includes all modifications, equivalents, and alternatives falling within the spirit and scope of the invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Hereinafter, preferred embodiments of a piezo sensor and a method of manufacturing the same according to the present invention will be described in detail with reference to the accompanying drawings, wherein like reference numerals designate like or corresponding components A duplicate description thereof will be omitted.

1 is a use state diagram showing a state in which a piezoelectric sensor 100 according to an embodiment of the present invention is used. The piezo sensor 100 according to the present embodiment is embedded in a road as shown in Fig. That is, after the groove is formed on the road, the piezo sensor 100 is embedded in the groove, so that the piezo sensor 100 is installed on the road. The piezo sensor 100 embedded in the road senses the pressure of an automobile passing over the piezo sensor 100 and generates an electrical signal. The generated electrical signal is transmitted to a processing device (not shown) installed separately on the road side through the cable. On the basis of the received electric signal, the processing device (not shown) acquires information such as the type of the vehicle passing through the road, the traffic volume, and whether the vehicle is overloaded.

FIG. 2 illustrates a piezo sensor 100 according to an embodiment of the present invention. 2, the piezo sensor 100 according to the present embodiment includes a sensor unit 110 for converting a pressure of an automobile into an electric signal, a cable 110 for transmitting an electric signal generated by the sensor unit 110, (120). The configurations and functions of these components will be described later.

With reference to the above description, a method of manufacturing a piezo sensor according to an embodiment of the present invention will be described with reference to FIG. 3 is a flowchart illustrating a method of manufacturing a piezo sensor according to an embodiment of the present invention.

First, the first piezoelectric film 112 is wound on the surface of the conductor 111 along the longitudinal direction in a spiral shape ( S10 , FIG. 4) . The first piezoelectric film 112 wound on the surface of the conductor 111 that transmits an electric signal is a polymeric ferroelectric material obtained by polarizing the uniaxially stretched film of vinylidene fluoride resin (PVDF) at a high voltage. . At this time, the first piezoelectric film 112 may be in the form of a belt having a predetermined thickness, and one side edge of the first piezoelectric film 112 may be in a wavy shape. The shape of the first piezo film 112 will be described later in detail.

On the other hand, the first piezoelectric film 112 is wound to overlap a part of the first piezoelectric film 112, so that a multilayered piezoelectric film layer can be formed on the surface of the conductor 111. So that a current generated by the piezoelectric effect can stably flow through the conductor 111 and the first piezo film 112. [ 5 is a cross-sectional view showing a state in which the first piezo film 112 is wound on the surface of the conductor 111. The first piezo film 112 is wound so as to partially overlap the conductor 111, A layer is formed.

The first piezo film 112 may be wound on the surface of the conductor 111 and then the second piezo film 113 may be wound thereon again ( S15 , FIG. 6) . In this case, the second piezo film 113 can be wound in a direction symmetrical to the first piezo film 112 with respect to the longitudinal axis of the conductor 111. When the piezo film 112 and 113 are wound , Even if a phenomenon that the piezo film is pushed in one direction by an external force occurs in the course of burying the piezo sensor 100 according to the present embodiment on the road, the piezo film can be wound tightly on the surface of the conductor 111, 100 can be ensured. It is needless to say that the second piezo film 113 can also be wound so that a part thereof is overlapped as in the case of the first piezo film 112.

Next, the conductor 111 wound with the piezo films 112 and 113 is passed through the roller 200 to make the conductor 111 into a flat shape pressed up and down ( S20 , FIG. 7) . The conductor 111 and the piezo films 112 and 113 and the metal tube 114 to be described later constitute the sensor unit 110 in the piezo sensor 100. This process is a process in which the sensor unit 110 is pushed up and down This corresponds to a preliminary step for making a flat shape. The effect of the sensor unit 110 having a flat shape will be described later.

Meanwhile, the roller 200 may be heated to a predetermined temperature. In this case, the process of pressing the piezo films 112 and 113 using the roller 200 can be more faithfully performed. The temperature of the roller 200 may be maintained at a predetermined level by using a separate temperature control device 220. In this case, in the process of pressing the piezo films 112 and 113 using the rollers 200, Uniform thermal compression can be realized over the entirety of the heat sinks 112 and 113.

Then, the conductor 111 and the piezoelectric films 112 and 113 having a flat shape are inserted into the metal tube 114 ( S30 ) . The metal tube 114 is a metal tube surrounding the conductor 111 and the piezo films 112 and 113 to maintain the shape of the piezo sensor 100 and more specifically the shape of the sensor part 110, Thereby preventing breakage of the conductor 111 and the first piezo film 112.

Press suitably a metal tube 114 of a circular cross section prior to the above process to advance vertically in order to improve the ease of operation will also just prepared to correspond to the shape of the conductor 111 is made flat, the end surface of the metal tube 114 ( S25 , Fig. 8) . The conductor 111 and the piezo films 112 and 113 can be easily inserted into the metal tube 114 by flattening the metal tube 114 to some extent beforehand since the conventional metal tube 114 is circular in cross section. .

When the conductor 111 and the piezo films 112 and 113 are inserted into the metal tube 114, the metal tube 114 in which the conductor 111 is inserted is passed through the roller 200 to move the metal tube 114 up and down To form a pressed flat shape ( S40 , Fig. 9) . As described above, the conductor 111, the piezo films 112 and 113, and the metal tube 114 constitute the sensor unit 110 that senses the pressure in the piezo sensor 100 and generates an electric signal. As shown in FIG. 10, the sensor unit 110 has a flat shape pressed downward through this process.

When the sensor unit 110 is flat and has a flat shape such that the width of the sensor unit 110 is larger than that of the upper and lower depths, the piezo films 112 and 113 and the metal tube (not shown) 114) can be increased, and a C value (charge amount) that can obtain an ideal output voltage can be obtained. In addition, since the sensor unit 110 has a flat shape as a whole, the depth of grooves to be machined on the road can be reduced, damage to roads due to groove machining can be reduced, and groove machining can be facilitated.

In addition, it is possible to increase the pressure receiving area by the wheels of the vehicle, so that a relatively high output voltage can be obtained compared with the case where no pressure is applied, and the sensor sensitivity can be improved. have.

Meanwhile, one end of the sensor unit 110 may be sealed by an insulating cap 150, as shown in FIG.

The more the fabrication of the sensor unit 110 through the process, and connect the cable 120 and sensor unit 110 for transmitting an electric signal to a separate processor (not shown) generated in the sensor section 110 ( S50 , Fig. 11) . In the present embodiment, for convenience of description, a bipolar electric wire including a first polar line 121 and a second polar line 122 is taken as an example of the cable 120. [ That is, when the bipolar wire is used as the cable 120, the conductor 111 is connected to the first pole 121 and the metal tube 114 is connected to the second pole 122 by soldering, And the cable 120 can be electrically connected to each other.

In this embodiment, a bipolar electric wire is shown as the cable 120, but the present invention is not limited thereto. Any cable capable of transmitting an electric signal generated by the sensor unit 110 may be used as the cable 120 So that the connection structure between the sensor unit 110 and the cable 120 can be changed.

After the sensor unit 110 and the cable 120 are connected to each other, the corresponding connection unit may be covered again through an insulator such as the shrink tube 141 and the protection tube 142 ( S60 , FIG. 12, and FIG. 13) . The shrink tube 141 may function to support the solder connection portion between the sensor portion 110 and the cable 120 so that the solder connection portion may be firmly held. The protection tube 142 may protect the connection portion from external impact Can be performed.

The protection tube 142 may be made of a known material such as metal or plastic, and a separate filling material (not shown) may be injected into the inner space of the protection tube 142. At this time, the filling material may be a material that solidifies upon cooling of the gel-state plastic or the bond, and the filling material may be injected into the protective pipe 142 and then cooled and solidified.

The outside of the protective pipe 142 may be covered by the outer tube 143 again, as shown in Fig. The outer tube 143 that surrounds the protection tube 142 can prevent moisture from penetrating by blocking the boundary between the sensor unit 110 and the cable 120 and the protection tube 142 from the outside, The appearance of the display panel can be prevented from being damaged.

A photomicrograph of the piezo sensor 100 manufactured through the above process is shown in Fig.

Hereinafter, an embodiment of a method of manufacturing a piezo sensor according to an aspect of the present invention will be described. Hereinafter, a structure of a piezo sensor according to another aspect of the present invention will be described. The piezo sensor to be described below can be manufactured by the same or similar method as the above-described manufacturing method, so that the description overlapping with the above-described portion can be omitted in describing the structure and function.

2 is a perspective view showing a piezo sensor 100 according to an embodiment of the present invention. Referring to FIG. 2, a piezo sensor 100, a sensor unit 110, a cable 120, an outer tube 143, and a cap 150 are shown. The piezo sensor 100 according to the present embodiment includes a sensor unit 110 for converting a pressure of an automobile into an electric signal; And a cable 120 for transmitting an electric signal generated by the sensor unit 110.

As shown in FIG. 10, the sensor unit 110 senses the pressure of the vehicle, and includes a conductor 111 positioned at the center and performing the function of transmitting an electric signal. A first piezoelectric film (112) wound in a spiral shape along the longitudinal direction of the conductor (111); And a metal tube 114 surrounding the first piezo film 112 to prevent damage to the conductor 111 and the first piezo film 112.

The first piezoelectric film 112 wound on the surface of the conductor 111 generates an electric current in accordance with the pressure externally applied. The generated current flows through the conductor 111 and a cable 120 And can be transmitted to a processing apparatus (not shown). At this time, the first piezoelectric film 112 may be in the form of a belt having a predetermined thickness, and one side edge of the first piezoelectric film 112 may be in a wavy shape.

The metal tube 114 is a metal tube surrounding the conductor 111 and the first piezo film 112 to maintain the shape of the piezo sensor 100 and to electrically connect the conductor 111 and the first piezo film 112 to each other. Thereby preventing breakage of the battery.

As shown in FIG. 10, the sensor unit 110 having the conductor 111, the first piezo film 112, and the metal tube 114 as its main components is formed so as to have a greater width than the upper and lower depths, So that it has a flat shape. That is, the upper surface of the sensor unit 110 has a flat shape so as to more accurately detect the pressure of the automobile, and the width of the sensor unit 110 is larger than that of the upper and lower depths. The effect obtained when the sensor unit 110 is pushed up and down to have a flat shape is as described in the description of the above-described manufacturing method.

As shown in Figs. 4 and 5, the first piezoelectric film 112 is wound spirally along the longitudinal direction on the surface of the conductor 111. As shown in Fig. At this time, the first piezoelectric film 112 is wound to overlap a part of the first piezoelectric film 112, so that a multilayered piezoelectric film layer can be formed on the surface of the conductor 111. Whereby a current generated by the piezoelectric effect can stably flow through the conductor 111 and the piezo film.

On the other hand, as shown in FIGS. 6 and 10, the second piezo film 113 may be further wound on the first piezo film 112. In this case, the second piezo film 113 can be wound in a direction symmetrical to the first piezo film 112 with respect to the longitudinal axis of the conductor 111. [ If the piezoelectric film 112 and 113 are doubly wound on the surface of the conductor 111, even if the piezoelectric film 100 is pushed in one direction by an external force during the process of burying the piezo sensor 100 according to the present embodiment on the road, The piezo film can be wound tightly and the reliability of the piezo sensor 100 can be ensured. It is needless to say that the second piezo film 113 can also be wound so that a part thereof is overlapped as in the case of the first piezo film 112.

On the other hand, as shown in FIGS. 4 and 6, the first piezoelectric film 112 and / or the second piezoelectric film 113 may have a shape in which one corner is corrugated and the other corner is straight . If one side is waved in this manner, the waste of the piezo films 112 and 113 can be reduced, and economical advantages can be obtained.

11, the sensor unit 110 and the cable 120 are connected to each other. In the above-described sensor unit 110, an electrical signal is generated by the pressure of the automobile. The electrical signal thus generated is transmitted to a separate processing device (not shown) through the cable 120. That is, the cable 120 is a means for transmitting an electrical signal generated by the sensor unit 110 to a processing apparatus (not shown).

The cable 120 may be a bipolar wire comprising a first pole 121 and a second pole 122. In this case the piezo sensor 100 may be connected to the bipolar wire by a lead have. For example, the conductor 111 may be soldered to the first polarity line 121 and the metal tube 114 may be soldered to the second polarity line 122, respectively. In this embodiment, a bipolar electric wire is shown as the cable 120, but the present invention is not limited thereto. Any cable capable of transmitting an electric signal generated by the sensor unit 110 may be used as the cable 120 So that the connection structure between the sensor unit 110 and the cable 120 can be changed.

12 and 13, the connecting portion between the cable 120 and the piezo sensor 100 may be covered again through the shrink tube 141 and the protective tube 142. [ The shrink tube 141 may function to support the solder connection portion between the sensor portion 110 and the cable 120 so that the solder connection portion may be firmly held. The protection tube 142 may protect the connection portion from external impact Can be performed.

The protection tube 142 may be made of a known material such as metal or plastic, and a separate filling material may be injected into the inner space of the protection tube 142. At this time, the filling material may be a material that solidifies upon cooling of the gel-state plastic or the bond, and the filling material may be injected into the protective pipe 142 and then cooled and solidified.

As shown in Fig. 14, the outer surface of the protective tube 142 can be covered with the outer tube 143 again as described above. Fig. 15 shows a real picture of the piezo sensor 100 having the above-described structure.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention as defined in the appended claims. It will be understood that the invention may be varied and varied without departing from the scope of the invention.

Many embodiments other than the above-described embodiments are within the scope of the claims of the present invention.

100: Piezo sensor
110:
111: Conductor
112: first piezo film
113: second piezo film
114: metal tube
120: Cable
121: first polar line
122: second pole
141: shrink tube
142: Protector
143: outer tube
150: cap
200: Rollers
220: Temperature control device

Claims

1. A method of manufacturing a piezo sensor embedded in a road and sensing pressure by an automobile passing on the road to obtain traffic information of the automobile,
(a) winding a first piezoelectric film in a spiral shape along a longitudinal direction on a surface of a conductor; Wherein the first piezo film is wound to partially overlap
(b) passing the conductor wound with the first piezo film through a roller to form the conductor into a flat shape pressed up and down;
(c) inserting the conductor into which the first piezoelectric film wound in a flat shape is wound, into a metal tube; And
(d) passing the metal tube into which the conductor is inserted, through a roller to make the metal tube into a flat shape pressed up and down.

The method according to claim 1,
Before the step (c)
Further comprising the step of pressing up and down a metal tube having a circular cross section in advance.

The method according to claim 1,
Prior to step (b) above,
And winding the second piezo film on the first piezo film in a direction symmetrical to the first piezo film with respect to the longitudinal axis.

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