JP2012198109A - 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 element 1 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 1 is mounted; a housing 4 that is provided with an element housing part 40 for housing the wave transmitting and receiving element 1 and a board mounting part 41 for mounting the circuit board 3 and that is formed with an insertion opening 42 for communicating the element housing part 40 with the board mounting part 41; a pin terminal 11 for electrically connecting the wave transmitting and receiving element 1 and the electronic circuit on the circuit board 3 via the insertion opening 42; and a sealing plate 6 for sealing the insertion opening 42. The circuit board 3 is coated with a coating material 7 having insulation over a whole area thereof.

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. Further, there is a problem in that costs such as depreciation and the like increase because the capital investment required for joining the lid member 105 to the opening periphery of the housing 105 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 and a housing on which the wave receiving / receiving block is mounted and a board mounting portion on which the circuit board is mounted are provided, and the circuit board is coated with an insulating coating material It is characterized by that.

  In this ultrasonic sensor, one end of an external connection terminal for receiving power supply from an external power source is connected to the circuit board, and the electrical connection between the wave transmitting / receiving element and the electronic circuit of the circuit board is electrically connected. The member and the external connection terminal are preferably coated with an insulating coating material.

  In this ultrasonic sensor, the conducting member is preferably a lead wire.

  In the present invention, since the circuit board is coated with an insulating coating material, waterproofness can be ensured without increasing the number of components, and an increase in weight and cost can be suppressed, and distortion of the circuit board can be prevented. Can be prevented.

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 sectional drawing which shows another structure same as the above. (A), (b) is sectional drawing which shows the case where an element storage part same as the above is removed. 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. Further, the present embodiment includes a housing 4 in which an element storage unit 40 in which the transmission / reception block 1 is stored and a substrate mounting unit 41 on which the circuit board 3 is mounted are provided. 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 a conducting member that electrically connects the wave transmitting / receiving block 1 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 placed on the board placement portion 41 on the upper side of the housing 4, and the pin terminals 11 through the through holes 20 and the insertion openings 42 described later are connected by soldering as described above. Is done. An electronic component 30 that constitutes an electronic circuit is mounted on the upper surface of the circuit board 3. Of course, the electronic component 30 is not limited to that shown in FIG. 1, and various components, large and small, are mounted on the upper surface or both upper and lower surfaces of the circuit board 3. The circuit board 3 is placed on the board placing portion 41 and bonded by a method such as adhesion using an adhesive.

  Here, the entire surface of the circuit board 3 is coated with a coating material 7 having insulating properties. For this reason, since the electronic circuit mounted on the circuit board 3 is covered with the coating material 7, it is possible to prevent water from entering from the outside.

  As shown in FIG. 1, the housing 4 has a substrate placement portion 41 having a space for placing the circuit board 3 on the upper surface thereof, and a substrate placement portion sandwiching a partition wall 43 at the bottom of the substrate placement portion 41. And a bottomed cylindrical element storage portion 40 adjacent to 41. 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 opening 42 for allowing the lower portion of the substrate mounting portion 41 and the upper portion of the element storage portion 40 to communicate with each other and let the pin terminal 11 pass therethrough.

  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> A are formed on the bottom surface of the substrate platform 41 so as to protrude upward. The support ribs 41A are respectively provided at the left and right end portions of the bottom surface of the substrate mounting portion 41, and the left and right end portions of the circuit board 3 are mounted on the support rib 41A.

  As shown in FIG. 1, a recess 41 </ b> B is provided at the bottom of the substrate mounting portion 41 at a position facing the element storage portion 40, and one end of the insertion opening 42 is open on the bottom surface of the recess 41 </ b> B. .

  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 protrudes into a cylindrical connector portion 44 projecting from the outer surface of the housing 4, and the other end protrudes above the substrate placement portion 41 through one support rib 41 </ b> A. Here, one end of the external connection terminal 5 is connected to an external terminal (not shown), and the other end protrudes from the board mounting 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 recess 41 </ b> B of the substrate platform 41 with the recess 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 bonded to the bottom surface of the recess 41B of the substrate mounting portion 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 element storage portion 40 from the outside via the substrate mounting portion 41 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 is coated with the insulating coating material 7. 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. Further, since there is no need to house the circuit board 3 in the housing 4 as in the conventional example, there is no opening in the upper portion of the housing 4, and therefore a lid member for closing the opening of the housing 4 is prepared separately. Since there is no need, the number of parts can be reduced. Furthermore, since the circuit board 3 and the substrate mounting portion 41 are joined by a method other than welding such as bonding using an adhesive, the equipment required for welding is not required, so initial investment such as capital investment is made. The fixed costs such as depreciation can be reduced.

  By the way, as shown in FIG. 2, the pin terminal 11 and the external connection terminal 5 may be coated with a coating material 7. In this case, since the pin terminal 11 and the external connection terminal 5 are covered with the coating material 7, vibration due to external stress can be attenuated, and the vibration resistance of the pin terminal 11 and the external connection terminal 5 can be improved. it can. Further, even if water enters between the circuit board 3 and the substrate mounting portion 41, the pin terminal 11 is covered with the coating material 7, so that water is prevented from adhering to the pin terminal 11. Can do.

  When the pin terminal 11 and the external connection terminal 5 are coated with the coating material 7, first, one end of the pin terminal 11 and the external connection terminal 5 is connected to the circuit board 3 by soldering. Thereafter, the coating on the pin terminal 11 and the external connection terminal 5 is completed by applying a coating material 7 having a low viscosity on the circuit board 3.

  Further, in the present embodiment, the pin terminal 11 is adopted as a conductive member that electrically connects the electronic circuit of the circuit board 3 and the wave transmitting / receiving element. However, as shown in FIG. May be adopted. In this case, a terminal portion (not shown) for connecting the wave transmitting / receiving element can be provided at an arbitrary location on the circuit board 3. That is, when the pin terminal 11 is employed, the pin terminal 11 cannot be bent, and therefore the position of the terminal portion on the circuit board 3 is determined depending on the location of the transmission / reception block 1. On the other hand, when the lead wire 12 is employed, the lead wire 12 can be bent, so that the terminal portion can be provided at any place on the circuit board 3 as described above. The lead wire 12 is preferably coated with the coating material 7.

  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 (conductive member)
12 Lead wire 3 Circuit board 4 Housing 5 External connection terminal 41 Board mounting part 42 Insertion opening 7 Coating material

Claims (3)

  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 the transmission / reception wave An ultrasonic sensor comprising: a housing on which a block is mounted and a substrate mounting portion on which the circuit board is mounted; and the circuit board is coated with an insulating coating material .   One end of an external connection terminal for receiving power supply from an external power source is connected to the circuit board, and a conductive member for electrically connecting the wave transmitting / receiving element and an electronic circuit of the circuit board and the external connection terminal The ultrasonic sensor according to claim 1, wherein coating is performed with a coating material having an insulating property.   The ultrasonic sensor according to claim 2, wherein the conducting member is a lead wire.

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