JP2012198108A - Ultrasonic sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an ultrasonic sensor that is capable of ensuring waterproofness without increasing the number of components, suppressing an increase in weight and cost, and preventing occurrence of distortion in a circuit board.SOLUTION: An ultrasonic sensor comprises: a wave transmitting and receiving block 1 for housing a wave transmitting and receiving element for transmitting and receiving an ultrasonic wave; a circuit board 3 on which an electronic circuit for processing an ultrasonic signal transmitted and received via the wave transmitting and receiving element is mounted; a housing 4 in which an opening 41A is included and the wave transmitting and receiving block 1 is mounted; conduction means for electrically connecting the wave transmitting and receiving element and the electronic circuit on the circuit board 3 via an insertion opening 42 provided in the housing 4; and a sealing plate 6 for sealing the insertion opening 42. The opening 41A of the housing 4 is closed by the circuit board 3.

Description

  The present invention relates to an ultrasonic sensor that is mounted on a vehicle or the like and used for obstacle detection or the like.

  Conventionally, as shown in FIG. 5, a hollow housing 101 having an opening on one surface, and a transmission / reception element (transmission / reception block) in which a transmission / reception surface on which ultrasonic transmission / reception is performed is exposed on the other surface of the housing 101. 102 is provided. This ultrasonic sensor includes a circuit board 103 on which an electronic circuit for processing an ultrasonic signal received in the housing 101 and transmitted / received via the transmitting / receiving element 102 is mounted, and the transmitting / receiving element 102 and the circuit board. And a wiring 104 for electrically connecting the terminal 103 to the terminal 103. The ultrasonic sensor includes a lid member 105 provided so as to cover the opening of the housing 101, and a terminal 106 having one end connected to the circuit board 103 by welding or the like and the other end connected to a power supply terminal (not shown). Prepare.

  And when the said ultrasonic sensor is used for vehicles, the said ultrasonic sensor is installed in a location with high possibility of being covered with water, such as a bumper and a front grill, and intense vibration. For this reason, in many conventional ultrasonic sensors, the housing 101 in which the circuit board 103 is accommodated is filled with a filler 107 such as silicon or urethane having hydrophobicity and elasticity. Thus, the structure which ensures the high waterproof property and vibration resistance which are requested | required by filling the filler 107 in the housing 101 is common (for example, refer patent document 1).

JP 2005-24351 A

  However, in the above-described conventional example, filling the filling material 107 in the housing 101 not only increases the weight and cost, but also causes distortion in the circuit board 103 accommodated in the housing 101 due to the presence of the filling material 107. May occur. When the circuit board 103 is distorted, a stress is applied to a soldering portion between the electronic component mounted on the circuit board 103 and a crack may occur. Alternatively, there is a possibility that the detection area characteristics of the sensor change before and after filling with the filler 107. In addition, as a factor which produces distortion to the circuit board 103, there exists an external load accompanying the thermal expansion and contraction of the filler 107, for example. In addition, examples of changes in the detection area characteristics before and after filling include narrowing of the detection area.

  Therefore, as shown in FIG. 6, a sealing plate 108 is provided with a communication hole 101 </ b> C that communicates the substrate housing portion 101 </ b> A in which the circuit board 103 in the housing 101 is housed with the element housing portion 101 </ b> B in which the wave transmitting / receiving element 102 is housed. It is conceivable to seal with. According to this configuration, the opening of the housing 101 is closed with the lid member 105, so that the substrate storage portion 101 </ b> A is hermetically sealed, so that waterproofness can be ensured without using the filler 107.

  However, in the case of the above-described conventional example and the above-described configuration shown in FIG. 6, the lid member 105 is required to close the opening of the housing 101, so that there is a problem that the number of parts increases.

  The present invention has been made in view of the above points, and can ensure waterproofness without increasing the number of components, suppress an increase in weight and cost, and generate distortion of a circuit board. An object is to provide an ultrasonic sensor that can be prevented.

  The ultrasonic sensor of the present invention is mounted with a transmission / reception block that houses a transmission / reception element that transmits / receives ultrasonic waves, and an electronic circuit for processing an ultrasonic signal transmitted / received via the transmission / reception element. A circuit board, a housing having an opening and to which the transmission / reception block is attached, and a conductive means for electrically connecting the transmission / reception element and an electronic circuit of the circuit board through an insertion opening provided in the housing. And a sealing means for sealing the insertion opening, wherein the opening of the housing is closed by the circuit board.

  In this ultrasonic sensor, it is preferable that the electronic circuit is mounted on a surface of the circuit board facing the inside of the housing.

  In this ultrasonic sensor, it is preferable that the circuit board is disposed inside the housing, and a space between the circuit board and the opening of the housing is filled with a sealing material.

  In this ultrasonic sensor, the conduction means includes a terminal protruding from the transmission / reception block, and one end of an external connection terminal for receiving power supply from an external power source is connected to the circuit board. The external connection terminal is preferably electrically connected to the electronic circuit provided on the circuit board.

  In this ultrasonic sensor, it is preferable that the terminal and the external connection terminal are electrically connected to the electronic circuit by press-fitting one end thereof into an insertion hole provided in the circuit board.

  In this ultrasonic sensor, it is preferable that the housing is provided with a support rib that protrudes from the bottom of the housing toward the opening of the housing, and the circuit board is in contact with an end of the support rib.

  According to the present invention, the opening of the housing is closed by the circuit board, so that waterproofness can be ensured without increasing the number of parts, the increase in weight and cost is suppressed, and the distortion of the circuit board is prevented. can do.

It is sectional drawing which shows embodiment of the ultrasonic sensor which concerns on this invention. It is sectional drawing which shows the other structure same as the above. It is a figure which shows the other joining method of a pin terminal same as the above, and an external connection terminal, (a) is sectional drawing before insertion of a terminal, (b) is sectional drawing after insertion of a terminal. (A), (b) is sectional drawing which shows another structure same as the above. It is sectional drawing which shows the conventional ultrasonic sensor. It is sectional drawing which shows the other structure of the conventional ultrasonic sensor.

  Hereinafter, embodiments of an ultrasonic sensor according to the present invention will be described with reference to the drawings. In the following description, the vertical and horizontal directions in FIG. 1 are defined as the vertical and horizontal directions. In this embodiment, as shown in FIG. 1, a transmission / reception block 1 that transmits and receives ultrasonic waves, a cover 2 that covers an outer peripheral surface other than the transmission / reception surface of the transmission / reception block 1, and transmission / reception via the transmission / reception block 1. And a circuit board 3 on which an electronic circuit for processing a waved ultrasonic signal is mounted. In the present embodiment, an element storage unit 40 that stores the transmission / reception block 1 and a circuit storage unit 41 that includes an opening 41A and stores at least a part of an electronic circuit mounted on the circuit board 3 are provided. The housing 4 is provided. The housing 4 is formed with an insertion port 42 that allows the element storage portion 40 and the circuit storage portion 41 to communicate with each other. Further, in the present embodiment, an external connection terminal 5 having one end connected to the circuit board 3 and the other end connected to an external terminal (not shown), and a sealing plate 6 (sealing means) for sealing the insertion opening 42. Is provided.

  As shown in FIG. 1, the transmission / reception block 1 includes a transmission / reception element (not shown) made of a piezoelectric element, and a case 10 that houses the transmission / reception element therein. The case 10 is formed in a cylindrical shape from, for example, polybutylene terephthalate colored in black, and a wave transmitting / receiving element is housed in the inner bottom thereof. The lower surface of the case 10 is used as an ultrasonic wave transmitting / receiving surface.

  The wave transmitting / receiving block 1 has a lead wire (not shown) whose one end is electrically connected to the wave transmitting / receiving element, one end soldered to the other end of the lead wire, and the other end protruding outside the case 10. And a rod-shaped pin terminal 11. The other end of the pin terminal 11 is electrically connected to an electronic circuit mounted on the circuit board 3 by being soldered in a state of being inserted into an insertion hole (not shown) provided in the circuit board 3. . That is, the lead wire and the pin terminal 11 constitute conduction means for electrically connecting the wave transmitting / receiving element and the electronic circuit of the circuit board 3.

  As shown in FIG. 1, the cover 2 is formed in a bottomed cylindrical shape whose bottom surface is opened from an elastic material, and is assembled to the outer periphery of the case 10 so as to cover the wave transmitting / receiving block 1. On the upper surface of the cover 2, a through hole 20 for passing the pin terminal 11 of the transmission / reception block 1 is provided.

  As shown in FIG. 1, the circuit board 3 is connected to the pin terminals 11 through the through holes 20 and the insertion openings 42 by soldering as described above. An electronic component 30 that constitutes an electronic circuit is mounted on the lower surface of the circuit board 3. Of course, the electronic component 30 is not limited to that shown in FIG. The circuit board 3 is placed on the periphery of the opening 41A of the circuit housing 41 so that the electronic component 30 is housed in the circuit housing 41, and is joined by a method such as bonding using an adhesive. Thus, the circuit board 3 closes the opening 41 </ b> A of the circuit storage unit 41, so that it is possible to prevent water from entering the circuit storage unit 41 from the outside through the opening 41 </ b> A of the circuit storage unit 41.

  As shown in FIG. 1, the housing 4 has a bottomed box adjacent to the circuit storage part 41 with a hollow box-shaped circuit storage part 41 having an opening 41 </ b> A on the upper surface and a partition wall 43 on the inner bottom of the circuit storage part 41. It is comprised from the cylindrical element accommodating part 40. FIG. Note that the element storage portion 40 has an opening 40A on the lower surface thereof. Further, the partition wall 43 of the housing 4 is provided with an insertion port 42 that allows the lower part of the circuit storage part 41 and the upper part of the element storage part 40 to communicate with each other.

  As shown in FIG. 1, the transmission / reception block 1 to which the cover 2 is assembled is inserted into the element storage unit 40 until it comes into contact with the partition wall 43, and the transmission / reception surface of the transmission / reception block 1 is externally connected through the opening 40A. It is stored in a state where it can face.

  As shown in FIG. 1, a pair of support ribs 41 </ b> B are formed on the bottom surface of the circuit storage portion 41 so as to protrude upward. The support ribs 41B are provided at the left and right ends of the bottom surface of the circuit storage portion 41, and the left and right ends of the circuit board 3 are placed on the support ribs 41B. That is, the circuit board 3 contacts the upper end portions of the pair of support ribs 41B.

  As shown in FIG. 1, a recess 41C is provided at the bottom of the circuit storage portion 41 at a position facing the element storage portion 40, and one end of the insertion port 42 is opened on the bottom surface of the recess 41C.

  As shown in FIG. 1, the external connection terminal 5 is molded integrally with the housing 4 so as to penetrate the outer wall of the housing 4 by insert molding. One end of the external connection terminal 5 projects into a cylindrical connector portion 44 projecting from the outer surface of the housing 4, and the other end projects into the circuit housing portion 41. Here, one end of the external connection terminal 5 is connected to an external terminal (not shown), and the other end protrudes from the bottom surface of the circuit housing portion 41 and is electrically connected to the circuit board 3 by soldering or the like.

  Then, the electronic circuit of the circuit board 3 receives power supplied from an external power supply (not shown) via the external connection terminal 5 and outputs a drive pulse signal to the wave transmitting / receiving element, and receives the drive pulse signal. The element transmits ultrasonic waves to the outside. Next, when receiving the reflected wave from the obstacle of the transmitted ultrasonic wave, the wave transmitting / receiving element outputs a received wave signal to the electronic circuit of the circuit board 3. The electronic circuit of the circuit board 3 calculates the distance from the time from the output of the drive pulse signal to the input of the received signal to the obstacle, and the signal including the calculation result is externally connected via the external connection terminal 5. To a control circuit (not shown).

  The sealing plate 6 is formed in a rectangular plate shape from, for example, translucent white polybutylene terephthalate. As shown in FIG. 1, a concave portion 60 that is depressed downward is formed in the center portion thereof. That is, the sealing plate 6 includes a recess 60 and a flange 61 formed on the periphery of the recess 60. The sealing plate 6 is provided in the concave portion 41 </ b> C of the circuit housing portion 41 with the concave portion 60 fitted in the insertion opening 42. Further, a through hole (not shown) is formed in the bottom surface of the recess 60 in the sealing plate 6, and the pin terminal 11 of the wave transmitting / receiving block 1 is passed through the through hole.

  The sealing plate 6 has a flange 61 joined to the bottom surface of the recess 41 </ b> C of the circuit housing 41 by ultrasonic welding or laser welding. The welding method is not limited to the above method, and vibration welding or the like may be used. Moreover, you may adhere | attach using an adhesive agent instead of performing welding. Thereby, the gap between the sealing plate 6 and the housing 4 is closed.

  Further, the sealing plate 6 has the bottom surface of the recess 60 in contact with the top surface of the case 11 of the transmission / reception block 1 through the insertion hole 42 and the through hole 20 of the cover 2, and the top surface and the bottom surface of the recess 60 are ultrasonically welded. They are joined by vibration welding or adhesion using an adhesive. As a result, the gap between the sealing plate 6 and the transmission / reception block 1 is closed. Thus, by sealing the insertion opening 42 with the sealing plate 6, it is possible to prevent water from entering the circuit storage section 41 from the outside via the element storage section 40 and the insertion opening 42. In this embodiment, the insertion port 42 is sealed by the sealing plate 6, but it is not necessary to be limited to this. For example, the insertion port 42 is sealed by filling the insertion port 42 with a filler. It may be configured to.

  As described above, in the present embodiment, the circuit board 3 closes the opening 41 </ b> A of the housing 4, so that the housing 4 can be sealed without filling the housing 4 with a filler. For this reason, since there is no filler around the circuit board 3 that may stress the circuit board 3, an increase in weight and cost is suppressed while ensuring waterproofness, and distortion of the circuit board 3 is prevented. Can be prevented. In addition, since it is not necessary to separately prepare a lid member for closing the opening 41A of the housing 4, the number of parts can be reduced. Furthermore, by using the circuit board 3 instead of the lid member, the thickness dimension of the housing 4 can be reduced by the thickness dimension of the circuit board 3, and thus the height of the sensor can be reduced.

  In this embodiment, when the opening 41 </ b> A of the housing 4 is closed with the circuit board 3, the circuit board 3 and the periphery of the opening 41 </ b> A are joined by a method other than welding such as adhesion using an adhesive. For this reason, since the equipment required for welding is not required, it is not necessary to make an initial investment such as capital investment, so that it is possible to reduce fixed costs such as depreciation costs.

  In the present embodiment, as shown in FIG. 1, the upper end portion of the support rib 41 </ b> B is in contact with the lower surface of the circuit board 3. For this reason, the stress applied to the circuit board 3 due to heat, vibration from the outside, or the like can be reduced. Moreover, in this embodiment, as shown in FIG. 1, the electronic component 30 is mounted only on one side (lower surface) of the circuit board 3, that is, the electronic circuit is mounted. For this reason, compared with the case where an electronic circuit is mounted on the upper and lower surfaces of the circuit board 3, the cost required for mounting can be reduced.

  By the way, in this embodiment, the opening 41A of the housing 4 is closed only by the circuit board 3, but the opening 41A is filled by filling the sealing material 7 in the space above the circuit board 3 as shown in FIG. It may be configured to close. In this case, the pair of support ribs 41B is positioned below the periphery of the opening 41A, and the left and right ends of the circuit board 3 are placed on the upper surface of each support rib 41B. Then, the space between the circuit board 3 and the opening 41 </ b> A is filled with the sealing material 7. For example, silicone having hydrophobicity and elasticity is used as the sealing material 7.

  By comprising in this way, since opening 41A of the housing 4 can be sealed more reliably, waterproofness can further be improved. Even if electronic circuits are mounted on both the upper and lower surfaces of the circuit board 3, the joint portion of the electronic component 30, the pin terminal 11, and the external connection terminal 5 can be protected by the sealing material 7.

  In the present embodiment, one end of the pin terminal 11 and the external connection terminal 5 are electrically connected to the circuit board 3 by soldering, but other connection methods may be used. For example, as shown in FIGS. 3A and 3B, one end portions of the pin terminal 11 and the external connection terminal 5 are formed in a shape having a spring property and press-fitted into an insertion hole 31 provided in the circuit board 3. It may be a method of electrically connecting with an electronic circuit by fitting together. In this case, since soldering becomes unnecessary when connecting the pin terminal 11 and the external connection terminal 5 to an electronic circuit, workability can be improved. Alternatively, a method of electrically connecting the electronic circuit by mounting a connector (not shown) on the circuit board 3 in advance and inserting the pin terminal 11 and the external connection terminal 5 into the connector may be used. .

  By the way, in the configuration of FIGS. 1 and 2 of the present embodiment, the transmission / reception block 1 is accommodated in the element accommodating portion 40. However, as shown in FIGS. 4A and 4B, the element accommodating portion 40 is excluded. Alternatively, the wave transmitting / receiving block 1 may be attached to the housing 4. In this configuration, the cover 2 assembled with the wave transmitting / receiving block 1 is attached to the periphery of the insertion opening 42 on the lower surface of the housing 4.

1 Transmission / reception block 11 Pin terminal (conduction means)
3 Circuit board 31 Insertion hole 4 Housing 41A Opening 41B Support rib 42 Insertion port 5 External connection terminal 6 Sealing plate (sealing means)
7 Sealing material

Claims (6)

  A transmission / reception block for accommodating a transmission / reception element for transmitting / receiving ultrasonic waves, a circuit board on which an electronic circuit for processing an ultrasonic signal transmitted / received via the transmission / reception element is mounted, and an opening In addition, a housing to which the transmission / reception block is attached, conduction means for electrically connecting the transmission / reception element and the electronic circuit of the circuit board through an insertion port provided in the housing, and the insertion port are sealed. An ultrasonic sensor, wherein the opening of the housing is closed by the circuit board.   The ultrasonic sensor according to claim 1, wherein the electronic circuit is mounted on a surface of the circuit board facing the inside of the housing.   The ultrasonic circuit according to claim 1, wherein the circuit board is disposed inside the housing, and a space between the circuit board and the opening of the housing is filled with a sealing material. Sensor.   The conducting means includes a terminal protruding from the wave receiving / receiving block, and one end of an external connection terminal for receiving power supply from an external power source is connected to the circuit board, and the terminal and the external connection terminal are The ultrasonic sensor according to claim 1, wherein the ultrasonic sensor is electrically connected to the electronic circuit provided on a circuit board.   The terminal and the external connection terminal are electrically connected to the electronic circuit by press-fitting one end of the terminal and the external connection terminal into an insertion hole provided in the circuit board. Ultrasonic sensor.   6. The housing according to claim 1, wherein the housing is provided with a support rib protruding from a bottom portion thereof toward the opening of the housing, and the circuit board is in contact with an end portion of the support rib. The ultrasonic sensor according to item 1.

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