KR102543526B1 - Sensor for vehicle - Google Patents

Abstract

The present invention relates to a vehicle detection sensor in which a coating film having a thickness capable of maintaining efficient performance of the sensor cell is formed on the front surface of the sensor cell, and a hollow housing having a through hole communicating with the outside at one end and a receiving groove formed at the other end; a sensor cell disposed in the through hole and having one end exposed through the through hole; a rubber cap made of an elastic material formed in a hollow shape, coupled to an outer circumferential surface of the sensor cell protruding from the through hole, and inserted into the mounting hole; a PCB electrically connected to the sensor cell and disposed in the receiving groove; and a potting member filled in the receiving groove to hermetically seal one end of the rubber cap and the PCB from the outside.

Description

Vehicle detection sensor {SENSOR FOR VEHICLE}

The present invention relates to a detection sensor for a vehicle, and more particularly, to a detection sensor for a vehicle in which a coating film having a thickness capable of maintaining efficient performance of the sensor cell is formed on the front surface of the sensor cell.

In general, a detection sensor such as an ultrasonic sensor is mounted on either the front and rear or front and rear bumpers of a vehicle to detect objects and obstacles during parking and stopping.

A vehicle detection sensor uses an element having piezoelectric and electrostrictive characteristics as a vibration source, and in particular, a sensor generated through a piezoelectric element performs sensing using ultrasonic waves. The same number of rapid oscillations as

At this time, when the frequency applied to the piezoelectric element is 20 kHz or more, the piezoelectric element generates ultrasonic waves having a specific frequency band that humans cannot hear due to vibration.

That is, by intermittently transmitting ultrasonic pulse signals and receiving reflected waves from nearby obstacles, objects and obstacles are sensed.

As shown in FIG. 1, such a conventional general vehicle detection sensor includes a housing 1 having an accommodation groove therein, a sensor cell 2 for detecting an object, the housing 1 and the sensor cell 2 ) Is disposed between the rubber cap 3 for mounting the vehicle detection sensor to the bumper 6 of the vehicle, the PCB 4 electrically connected to the sensor cell 2, and the receiving groove of the housing 1 It includes a potting member 5 that is filled and blocks the PCB 4 from the outside.

By accommodating the sensor cell 2, the rubber cap 3 prevents interference with other parts so that the sensor cell 2 vibrates freely when the sensor cell 2 vibrates, and the vibration of the sensor cell 2 It acts as an anti-vibration preventing it from being transmitted to other parts.

The rubber cap 3 is fixed to the housing 1 while accommodating the sensor cell 2 .

Here, the rubber cap 3 to which the sensor cell 2 is coupled is mounted on the bumper 6 of the vehicle. Since the sensor cell 2 vibrates with a natural frequency and vibration characteristics, the sensor cell 2 is mounted and the surrounding environment is affected. react sensitively.

Accordingly, the rubber cap 3 is made of a material having a thin thickness and low hardness to protect the sensor cell 2 from external interference and to help maintain vibration characteristics.

Meanwhile, when the detection sensor is mounted on the bumper 6 of the vehicle, the front surface of the sensor cell 2 is exposed to the outside of the bumper.

Therefore, the front surface of the sensor cell 2 should be painted in a color that matches the color of the bumper.

When the front surface of the sensor cell 2 is coated, the vibration of the piezoelectric element vibrating inside the sensor cell 2 is affected.

That is, when the coating thickness is thin, the effect on the performance of the detection sensor is small.

However, if the coating is applied for a long time or several layers of coating, the thickness of the coating becomes thick and the vibration of the piezoelectric element and the characteristic value of the characteristic impedance of the sensor cell (2) change. During transmission, a problem occurred in the section where the excitation waveform was generated due to the physical vibration of the ultrasonic sensor cell) and the sensitivity of the sensor cell 2.

That is, in the prior art, there has been a problem of deteriorating reliability of a product, such as causing a false detection of a sensor due to the thickness of the coating as described above.

For the above reasons, the field is seeking a method to prevent false detection of the sensor cell 2 by forming a coating thickness to maintain the efficient performance of the sensor cell 2, but satisfactory results have not been obtained so far. There is a situation.

The present invention has been proposed in view of the above situation, and by forming the thickness of the coating layer formed on the front surface of the sensor cell to a thickness capable of maintaining the efficient performance of the sensor cell, the product by reducing the false detection phenomenon of the sensor cell Its purpose is to provide a vehicle detection sensor that can improve reliability.

In order to achieve the above object, the vehicle detection sensor of the present invention is a vehicle ultrasonic sensor mounted on a vehicle bumper through which a mounting hole is formed, in which a through hole communicating with the outside is formed at one end and a receiving groove is formed at the other end. housing; a sensor cell disposed in the through hole and having one end exposed through the through hole; a sound absorbing material filled in the sensor cell; a rubber cap made of an elastic material formed in a hollow shape, coupled to an outer circumferential surface of the sensor cell protruding from the through hole, and inserted into the mounting hole; a PCB electrically connected to the sensor cell and disposed in the receiving groove; and a potting member filled in the receiving groove to hermetically seal one end of the rubber cap and the PCB from the outside.

The sensor cell includes a bottom portion whose front surface is exposed from the through hole and which is in surface contact with the piezoelectric element 250 on the rear surface; and a side wall portion extending in a vertical direction from the bottom portion, wherein the thickness of the bottom portion is smaller than that of the side wall portion.

The front surface of the bottom part further includes a coating layer preventing rust from occurring on the front surface of the bottom part.

The thickness of the coating layer is made of 40 μm to 88.6 μm.

The added thickness of the coating layer and the bottom portion is smaller than or equal to the thickness of the side wall portion.

The coating layer is made of any one of aminoalkyd resin, fluorine resin varnish, acrylic resin, and polyurethane resin.

The sensor cell includes a connecting member electrically connected to the sensor cell at one end and electrically connected to the PCB at the other end.

The potting member is made of silicon.

It further includes a; cover member coupled to the other end of the housing to hermetically seal the inside of the housing.

In the vehicle detection sensor according to the present invention, the thickness of the coating layer is made of 40 μm to 88.6 μm, so that false detection of the sensor cell due to the thickness of the coating layer formed on the front surface of the sensor cell can be reduced, and the reliability of the vehicle detection sensor can improve.

In addition, since the added thickness of the coating layer and the bottom portion is thinner than or equal to the thickness of the side wall portion, reliability of the vehicle detection sensor can be further improved.

The front surface of the sensor cell, which is one end of the housing, is exposed to the outside of the housing through the through hole, so that signals transmitted and received from the outside of the housing to and from the sensor cell can be clearly transmitted and received.

Since the housing is separated into two or more parts and assembled after manufacturing, various parts such as sensor cells, rubber caps, and PCBs can be smoothly assembled.

Since the rubber cap is formed of an elastic material, it can be easily coupled to the through-hole of the housing, and the outer circumferential surface of the rubber cap is strongly adhered to the inner circumferential surface of the through-hole to effectively prevent the rubber cap from being separated from the through-hole.

This potting member blocks various parts accommodated inside the housing, such as PCB, from the outside to make it airtight, so that the potting member protects various parts, such as PCB, accommodated inside the housing from external impact or shaking and foreign substances that have flowed into the housing from the outside. It can be protected to extend the life of the vehicle detection sensor.

1 is a cross-sectional view of a vehicle detection sensor according to the prior art.
Figure 2 is an exploded perspective view of a vehicle detection sensor according to an embodiment of the present invention.
3 is a cross-sectional view of a vehicle detection sensor according to an embodiment of the present invention.

Advantages and features of the present invention, and methods of achieving them, will become clear with reference to the detailed description of the following embodiments taken in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various different forms, only these embodiments make the disclosure of the present invention complete, and common knowledge in the art to which the present invention belongs. It is provided to fully inform the holder of the scope of the invention, and the present invention is defined by the description of the claims. Meanwhile, terms used in this specification are for describing the embodiments and are not intended to limit the present invention. In this specification, singular forms also include plural forms unless specifically stated otherwise in a phrase. As used herein, "comprises" or "comprising" means the presence or absence of one or more other elements, steps, operations and/or elements other than the recited elements, steps, operations and/or elements; do not rule out additions.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 2 is an exploded perspective view of a vehicle detection sensor according to an embodiment of the present invention, Figure 3 is a cross-sectional view of the vehicle detection sensor according to an embodiment of the present invention.

As shown in FIGS. 2 and 3, the vehicle detection sensor mounted on the vehicle bumper through which the mounting hole is formed includes a housing 100, a sensor cell 200, a sound absorbing material 300, a rubber cap 400, It includes a PCB 500, a potting member 600 and a cover 700.

The housing 100 is a body accommodating the PCB 500 and various components, and has a through hole 110 formed in one direction and an accommodation groove 120 formed open in the other direction, thereby forming the through hole 110 and the accommodation groove. (120) is made of a mutually communicating hollow shape.

The through hole 110 is preferably formed in a circular shape in which one end of the housing 100 communicates with the outside, communicates with the receiving groove 120, and is a hole into which the rubber cap 400 is inserted.

The through hole 110 is a hole in which the sensor cell 200 is disposed so that the front surface of the sensor cell 200 protrudes from the housing 100 .

Therefore, the through hole 110 clearly receives or transmits signals transmitted or received from the outside of the housing 100 to the sensor cell 200 by exposing the front surface of the sensor cell 200 to the outside of the housing 100. can do.

The accommodating groove 120 is a hole through which the PCB 500 and various components are accommodated into the housing 100 from the outside in the direction of the other end of the housing 100 .

Accordingly, one end direction and the other end direction of the housing 100 are formed in a hollow shape communicated with each other by the through hole 110 and the receiving groove 120 .

In addition, the housing 100 may be manufactured by being separated into two or more pieces to smoothly assemble the sensor cell 200, the rubber cap 400, and the PCB 500, and then assemble them.

The sensor cell 200 detects an object by generating and receiving ultrasonic waves, and is preferably coupled to the through hole 110 via the rubber cap 400 .

In addition, the front surface of the sensor cell 200 in one direction of the housing 100 is exposed through the through hole 110 .

That is, as the sensor cell 200 is exposed to the outside of the housing 100 through the through hole 110, a signal transmitted or received from the outside of the housing 100 to the sensor cell 200 can be clearly received or transmitted. can

The sensor cell 200 includes a bottom portion 210, a side wall portion 220, a connecting member 230, and a coating layer 240.

The front surface of the bottom portion 210 is exposed through the through hole 110, and the piezoelectric element 250 is in surface contact with the rear surface.

Therefore, when the piezoelectric element 250 is mounted on the bottom part 210 and a pulse type electrical signal is applied regularly or irregularly, vibration is generated.

That is, the sensor cell 200 transmits ultrasonic waves caused by friction with the bottom part 210 of the sensor cell 200 by the vibration of the piezoelectric element 250, and then generates reflected ultrasonic waves that are reflected when they hit obstacles around the vehicle. Received, and the received ultrasonic signal is transmitted to the PCB (500).

The side wall portion 220 extends from the bottom portion 210 in a vertical direction.

Due to this, an accommodation space is formed inside the sensor cell 200 to accommodate the piezoelectric element 250 .

Meanwhile, the piezoelectric element 250 generates vibration as described above, and generates vibration due to friction with the bottom portion 210 .

Therefore, the bottom portion 210 is preferably made of a thin thickness, more specifically, it is preferable to be formed thinner than the thickness of the side wall portion 220.

Due to this, vibration due to friction with the piezoelectric element 250 is more effectively generated in the bottom part 210 to transmit and receive ultrasonic waves.

As shown in FIG. 3, the connection member 230 has one end electrically connected to the sensor cell 200 and the other end electrically connected to the PCB 500.

Also, the connection member 230 is preferably coupled to the PCB 500 and the sensor cell 200 by soldering.

In addition, the connection member 230 is preferably made of a lead wire or the like.

The coating layer 240 coats the entire surface of the bottom portion 210 to prevent rust on the entire surface of the bottom portion 210 .

In addition, since the front surface of the bottom part 210 is exposed to the outside of the through hole 110 and the outside of the bumper at the same time, the coating film layer 240 is formed such that the front surface of the bottom part 210 is in harmony with the bumper of the vehicle. It should be formed in color.

The coating layer 240 is formed by mounting the sensor cell 200 on a jig and spraying the entire surface of the sensor cell 200 in a spray injection method.

The coating layer 240 is preferably made of any one of aminoalkyd resin, fluorine resin varnish, acrylic resin, and polyurethane resin.

Meanwhile, the coating layer 240 according to an embodiment of the present invention has been described as being formed by spraying, but if the coating layer 240 can be formed on the front surface of the sensor cell 200, it can be configured as a film or the like. can also be formed.

On the other hand, when the thickness (D) of the coating layer 240 formed on the entire surface of the bottom portion 210 is thin, the effect on the performance of the detection sensor is small, but when the thickness (D) of the coating layer 240 is thick, The vibration of the piezoelectric element 250 and the characteristic impedance characteristic of the sensor cell 200 change, resulting in an excitation waveform due to the physical vibration of the ultrasonic sensor cell 200 when transmitting ultrasonic waves, which is an important management item for sensor performance. generated section) and the sensitivity of the sensor cell 200.

Therefore, the coating layer 240 formed on the entire surface of the bottom portion 210 should have an ideal thickness that does not affect the performance of the sensor cell 200 .

The applicant conducted experiments to obtain the above conditions, and the results are shown in the table below.

experimental courtesy preparation

The thickness D of the coating layer 240 formed on the front surface of the sensor cell 200 is prepared as shown in Table 1 below.

Experiment 1 : impedance characteristic value

According to the above experimental results, as the thickness (D) of the coating layer 240 becomes thicker, it can be seen that the change rate of the R1 value changes by up to about 40%.

Therefore, it can be confirmed that the resistance value of the sensor cell 200 is a characteristic value that changes most greatly as the thickness D of the coating layer 240 increases.

Experiment 2 : sensor performance

According to the above experimental results, as the thickness (D) of the coating film layer 240 increases, it can be confirmed that the sensitivity change rate of the sensor cell 200 decreases to -25% or less.

Such experimental results show that as the thickness (D) of the coating layer 240 formed on the front surface of the sensor cell 200 increases, the ultrasonic wave of the sensor cell 200 generated by the vibration source of the piezoelectric element 250 is transmitted to the outside. because it hinders

Experiment 3 : Correlation between impedance and sensitivity

According to the above experimental results, as the thickness (D) of the coating layer 240 increases, it can be seen that the change rate of the Q value decreases to -20% or less.

The quality of the ideal sensor cell 200 is summarized in Equation 1 below.

In the above formula, Q is a quality factor (frequency selection characteristic quality) and represents the ratio of energy to be stored and energy to be lost.

More specifically, the stored energy is electrical energy applied to the ceramic element to generate ultrasonic waves in the sensor cell 200, and the energy lost is due to the increased resistance value as the thickness D of the coating layer 240 increases. is the lost energy.

Experiment result

In summary of the above experiments, as shown in <Table 5>, the value of R1 increases as the thickness (D) of the coating layer 240 increases, and as the value of R1 increases, the Q value and the sensor cell (200 ) decreases the sensitivity.

That is, the thickness (D) of the coating layer 240 when the change rate of the Q value is 0% is the most suitable, and the thickness (D) of the coating layer 240 increases the R1 value change rate by 5% or more, and the sensor Based on Experimental Example D (102.1㎛) in which the sensitivity of the cell 200 is reduced by 5% or more, it is preferable to form Experimental Example C (88.6㎛) thinner than Experimental Example D.

In addition, since the front surface of the sensor cell 200 is exposed to the outside of the vehicle, the coating layer 240 also has a function of suppressing corrosion on the front surface of the sensor cell 200.

Therefore, the coating layer 240 must satisfy the weather resistance evaluation.

In general, the thickness (D) of the coating layer 240 should be 40 μm or more to satisfy the weather resistance evaluation.

That is, it is preferable that the ideal thickness of the coating layer 240 is 40 μm to 88.6 μm.

Due to this, it is possible to reduce the false detection of the sensor cell 200 due to the thickness (D) of the coating film layer 240 formed on the front surface of the sensor cell 200, thereby improving the reliability of the vehicle detection sensor.

Meanwhile, it is preferable that the added thickness of the coating layer 240 and the bottom portion 210 is thinner than or equal to the thickness of the side wall portion 220 .

Therefore, the sensor cell 200 is formed thinner than the thickness of the side wall portion 220 even when the thickness of the coating layer 240 and the bottom portion 210 are added, so that the reliability of the vehicle detection sensor can be further improved.

The sound absorbing material 300 reduces reverberation that appears after the piezoelectric element 250 generates ultrasonic waves, prevents ultrasonic waves from propagating to the other end of the housing 100, and prevents unnecessary vibration and noise.

The sound absorbing material 300 is filled in the inner space of the sensor cell 200 through the open other end of the sensor cell 200 .

As the sound absorbing material 300 is injected into the inner space of the sensor cell 200 and cured, the inside of the sensor cell 200 is hermetically sealed.

The rubber cap 400 is formed in a cylindrical shape corresponding to the through hole 110 so as to be coupled to the through hole 110, and the outer diameter of the rubber cap 400 is larger than or equal to the inner diameter of the through hole 110. do.

Due to this, when the rubber cap 400 is coupled to the through hole 110, they are strongly and tightly coupled to each other.

In addition, the rubber cap 400 is preferably made of an elastic material.

Therefore, when the rubber cap 400 is coupled to the through hole 110, the rubber cap 400 is elastically deformed and can be easily coupled to the through hole 110.

That is, the rubber cap 400 can easily couple the sensor cell 200 to the inside of the through hole 110, and the outer circumferential surface of the rubber cap 400 is strongly adhered to the inner circumferential surface of the through hole 110, so that the rubber cap 400 may be prevented from being separated from the through hole 110 .

The rubber cap 400 has a seating groove 410 formed thereon.

The seating groove 410 is formed inside the rubber cap 400, and the sensor cell 200 is seated therein.

To this end, the seating groove 410 is preferably formed in a cylindrical shape corresponding to the sensor cell 200.

In addition, the seating groove 410 penetrates in the other direction so that the connection member 230 connected to the sensor cell 200 can be exposed in the direction of the receiving groove 120 of the housing 100 and communicates with the receiving groove 120.

The PCB 500 is mounted inside the housing 100 through the receiving groove 120 of the housing 100, a conductor pattern is formed on one or both sides of the PCB 500, and various circuit elements are mounted. do.

The PCB 500 is electrically connected to the sensor cell 200 through the connecting member 230 and receives an ultrasonic signal from the sensor cell 200 .

In addition, various circuit elements may be mounted on the PCB 500 by a flip chip method using a conductive adhesive depending on their shape.

Then, after the PCB 500 is inserted into the receiving groove 120 of the housing 100, the housing 100 is filled with the liquid potting member 600.

The potting member 600 is preferably made of a liquid such as silicon, and is filled into the housing 100 through the receiving groove 120 of the housing 100 and then cured.

The potting member 600 blocks various components accommodated inside the housing 100, such as the PCB 500, from the outside to make them airtight.

Therefore, the potting member 600 can protect various components, such as the PCB 500 accommodated inside the housing 100, from external impact or shaking, and can protect them from foreign substances introduced into the housing 100 from the outside. Therefore, the lifetime of the vehicle detection sensor can be extended.

On the other hand, the potting member 600 is made of a silicone material that is hardened after filling the inside of the housing 100, and may be easily torn by external impact.

To prevent this, after the potting member 600 is filled in the housing 100 and cured, a cover 700 is mounted on the other end of the housing 100 .

The cover 700 is mounted on the other end of the housing 100 after the potting member 600 is filled in the housing 100 and cured.

Due to this, the cover 700 can easily protect the potting member 600 from external impact, thereby extending the life of the sensor cell 200.

As described above, in the vehicle detection sensor according to the present invention, the thickness (D) of the coating layer 240 is made of 40 μm to 88.6 μm, so that the thickness of the coating layer 240 formed on the front surface of the sensor cell 200 It is possible to reduce erroneous detection of the sensor cell 200 by (D) and improve the reliability of the vehicle detection sensor.

In addition, since the added thickness of the coating layer 240 and the bottom portion 210 is thinner than or equal to the thickness of the side wall portion 220, the reliability of the vehicle detection sensor can be further improved.

The front surface of the sensor cell 200, which is one end of the housing 100, is exposed to the outside of the housing 100 through the through hole 110, so that the sensor cell 200 is transmitted and received from the outside of the housing 100. Signals can be transmitted and received clearly.

Since the housing 100 is separated into two or more pieces and assembled after fabrication, various components such as the sensor cell 200, the rubber cap 400, and the PCB 500 can be smoothly assembled.

Since the rubber cap 400 is formed of an elastic material, it can be easily coupled to the through-hole 110 of the housing 100, and the outer circumferential surface of the rubber cap 400 is strongly adhered to the inner circumferential surface of the through-hole 110 to form a rubber cap. It is possible to effectively prevent the cap 400 from being separated from the through hole 110 .

The potting member 600 blocks various components accommodated inside the housing 100, such as the PCB 500, from the outside to make it airtight, so that the potting member 600 is accommodated inside the housing 100, such as the PCB 500. Components can be protected from external impact or shaking and foreign substances introduced into the housing 100 from the outside, so that the lifespan of the vehicle detection sensor can be increased.

The present invention is not limited to the above-described embodiments, and can be implemented with various modifications within the scope of the technical idea of the present invention.

100: housing 110: through hole
120: receiving groove 200: sensor cell
210: bottom part 220: side wall part
230: connecting member 240: coating layer
300: sound absorbing material 400: rubber cap
410: seating groove 500: PCB
600: potting member 700: cover

Claims (9)

In the vehicle ultrasonic sensor mounted on the vehicle bumper through which the mounting hole is formed,
A hollow housing having a through hole communicating with the outside at one end and a receiving groove formed at the other end;
a sensor cell disposed in the through hole and having one end exposed through the through hole;
a sound absorbing material filled in the sensor cell;
a rubber cap made of an elastic material formed in a hollow shape, coupled to an outer circumferential surface of the sensor cell protruding from the through hole, and inserted into the mounting hole;
a PCB electrically connected to the sensor cell and disposed in the receiving groove;
A potting member filled in the receiving groove to hermetically seal one end of the rubber cap and the PCB from the outside;
The sensor cell,
The front surface is exposed from the through hole and includes a bottom portion in surface contact with the piezoelectric element on the rear surface,
Further comprising a coating layer on the front surface of the bottom portion to prevent rust from occurring on the front surface of the bottom portion,
The thickness of the coating layer is
of 40 μm to 88.6 μm
In-vehicle detection sensor. The method of claim 1, wherein the sensor cell,
Further comprising a side wall portion extending in a vertical direction from the bottom portion,
The thickness of the bottom part is thinner than the thickness of the side wall part
In-vehicle detection sensor. delete delete According to claim 2,
The thickness of the coating layer and the bottom portion added to each other is thinner than or equal to the thickness of the side wall portion
In-vehicle detection sensor. The method of claim 2, wherein the coating layer,
Composed of any one of aminoalkyd resin, fluorine resin varnish, acrylic resin, and polyurethane resin
In-vehicle detection sensor. The method of claim 1, wherein the sensor cell,
Having a connecting member having one end electrically connected to the sensor cell and the other end electrically connected to the PCB
In-vehicle detection sensor. According to claim 1,
The potting member,
made of silicone
In-vehicle detection sensor. According to claim 1,
To further include a cover member coupled to the other end of the housing to hermetically seal the inside of the housing.
In-vehicle detection sensor.

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