Ultrasonic sensor and method of manufacturing the same

Abstract

An ultrasonic sensor includes a piezoelectric element, a cell case configured to support the piezoelectric element inside the cell case joined to a front portion of the cell case, the cell case having an opening at a rear portion thereof, a PCB assembly electrically connected to the piezoelectric element, a housing coupled to the opening of the cell case while accommodating the PCB assembly therein and configured to seal a space required for electrical connection between the piezoelectric element and the PCB assembly in the cell case, a filler filling the space required for the electrical connection between the piezoelectric element and the PCB assembly after the electrical connection between the piezoelectric element and the PCB assembly is completed, and a rear cover configured to seal a rear opening formed at the housing to allow insertion of the PCB assembly.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Korean Patent Application No. 10-2022-0102151, filed on August 16, 2022, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. Technical Field

[0003] This invention relates to technologies associated with ultrasonic sensors. Background Technology

[0004] Ultrasonic sensors use high-frequency ultrasonic waves, which are above the audible frequency range, to measure the position of a target object and the distance to that target object in a non-contact manner.

[0005] Since such ultrasonic sensors are used in vehicles and other applications, they should provide adequate and stable waterproofing. Furthermore, ideally, ultrasonic sensors should offer stable sensing performance while being inexpensive and simple to manufacture.

[0006] The matters disclosed in this section are provided only to enhance the understanding of the general background of the invention and should not be construed as an admission of related technology known to those skilled in the art or any form of implication. Summary of the Invention

[0007] Therefore, the present invention was made in view of the above-mentioned problems, and the object of the present invention is to provide an ultrasonic sensor that can provide stable sensing performance and waterproof performance while being inexpensive and simple to manufacture, as well as a method for manufacturing the ultrasonic sensor.

[0008] Those skilled in the art should understand that the technical problems to be solved by the present invention are not limited to the above-mentioned technical problems, and other technical problems will be more clearly understood from the following description.

[0009] According to one aspect of the invention, the above and other objectives can be achieved by providing an ultrasonic sensor comprising: a piezoelectric element; a housing configured to support the piezoelectric element joined to a front portion of the housing within the housing, the housing having an opening at a rear portion; a printed circuit board (PCB) assembly electrically connected to the piezoelectric element; a housing coupled to the opening of the housing while housing the PCB assembly therein, and configured to seal the space required for the electrical connection between the piezoelectric element and the PCB assembly within the housing; a filler that fills the space required for the electrical connection between the piezoelectric element and the PCB assembly after the electrical connection between the piezoelectric element and the PCB assembly is completed; and a rear cover configured to seal the rear opening formed at the housing to allow insertion of the PCB assembly.

[0010] The PCB assembly can be mounted to divide the interior of the housing into spaces connected to the unit housing and spaces connected to the back cover, thus isolating these spaces from each other.

[0011] Application-Specific Integrated Circuit (ASIC) can be disposed on the surface of the PCB assembly facing the cell housing, and the circuit element can be disposed on the surface of the PCB assembly facing the rear cover, wherein the volume of the circuit element protruding from the PCB assembly is greater than the volume of the ASIC protruding from the PCB assembly.

[0012] The back cover can be made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm. The back cover can be coupled to the housing by laser welding.

[0013] Connectors that are electrically connected to the outside can be formed in the housing, allowing the connector to be integrated with the housing. The connector pins of the connector can be insert-formed in the housing, such that the end of the connector pins connected to the PCB assembly protrudes parallel to the rear cover.

[0014] Lead pins can be inserted into the housing for electrical interconnection between the PCB assembly and the piezoelectric element. The lead pins are inserted into the housing such that the end of the lead pin connected to the PCB assembly protrudes parallel to the connector pins toward the rear cover. The PCB assembly can be press-fitted to the connector pins and lead pins.

[0015] The lead pins can be coupled to the housing by their linear movement in the forward / backward direction from one side of the back cover to one side of the unit housing, thus restricting the movement of the lead pins relative to the housing in any direction.

[0016] Each lead pin may include: a limiting portion configured to insert a lead insertion recess formed in the housing in front of one end of the lead pin being press-fitted in the PCB assembly, thereby limiting relative movement of the lead pin in a direction perpendicular to the forward / backward direction; and a press-fit protrusion protruding from the limiting portion in the forward / backward direction to press-fit in the housing.

[0017] The lead pin can bend toward the center portion of the opening in the cell housing after extending from the limiting portion in a forward / backward direction. A limiting protrusion can be provided in the housing to limit the opposite sides of the bent portion of the lead pin.

[0018] Wiring can be positioned between the other end of the lead pin and the piezoelectric element, such that the opposite ends of the wiring are connected to the lead pin and the piezoelectric element, respectively. The wiring may have at least one bend in its middle to prevent breakage due to the contraction and expansion of the filler.

[0019] The ultrasonic sensor may also include a rubber cap inserted between the unit housing and the housing, and a front cover assembled around the unit housing to surround the front of the rubber cap and the housing.

[0020] The housing may have an integrated structure including: a support portion configured to support the rear end of the unit housing when a rubber cap is inserted between the support portion and the rear end of the unit housing, and to allow an opening in the unit housing to communicate with the interior of the housing; and a front end configured to protrude from the outside of the support portion in a forward direction while being surrounded by a front cover.

[0021] The rubber cap may have an integrated structure comprising: a first sealing protrusion configured to press against the inner peripheral surface of a support portion of the housing, thereby sealing the inner peripheral surface of the support portion; a second sealing protrusion configured to press against the inner peripheral surface of the front end of the housing, thereby sealing the inner peripheral surface of the front end; and a third sealing protrusion configured to press against the outer peripheral surface of the unit housing, thereby sealing the outer peripheral surface of the unit housing.

[0022] The enlarged portion of the cross-section can be located at the rear of the outer peripheral surface of the unit housing. The third sealing protrusion can be formed at the position where the enlarged portion of the unit housing begins to press.

[0023] The front cover may be provided with a press-fit rib, which is configured to be press-fitted onto the front of the rubber cap. The rubber cap may be formed with a press-fit groove configured to receive the press-fit rib.

[0024] With the rubber cap pressed against the outer peripheral surface of the unit shell by the inclined surface formed inside the press-fit rib of the front cover, the front cover can be welded to the shell and the rubber cap by ultrasonic waves.

[0025] At least one rib may be formed at the support portion of the shell, such that the rib protrudes toward the front of the rubber cap.

[0026] According to another aspect of the present invention, a method for manufacturing an ultrasonic sensor is provided, the method comprising: attaching a piezoelectric element to a front portion of a unit housing inside a unit housing; assembling the unit housing to the front portion of a housing with a rubber cap inserted between the unit housing and the front portion of the housing, and welding a front cover to the rubber cap and the front portion of the housing with a front cover surrounding the rubber cap and the front portion of the housing; coupling wired lead pins to the housing; soldering the wires to the piezoelectric element for interconnection therebetween; injecting filler into the interior of the wired unit housing and the interior of the housing; inserting a printed circuit board (PCB) assembly into the housing such that the lead pins and connector pins with inserts formed in the housing are connected to the PCB assembly; and sealing the rear portion of the housing with the PCB assembly inserted by a rear cover.

[0027] Filler material can be injected so that it only fills the space facing the front of the PCB assembly. The PCB assembly can be inserted into the housing so that lead pins and connector pins are electrically interconnected via press-fit.

[0028] The back cover can be made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm, and can be laser welded to the rear of the housing made of plastic resin injection molding, thereby sealing the housing. Attached Figure Description

[0029] The above and other objects, features, and other advantages of the invention will be more clearly understood from the following detailed description given in conjunction with the accompanying drawings, in which:

[0030] Figure 1 This is a perspective view showing an ultrasonic sensor according to an exemplary embodiment of the present invention;

[0031] Figure 2 yes Figure 1 Exploded perspective view of the ultrasonic sensor;

[0032] Figure 3 This is an explanation Figure 1 A diagram of the internal structure of an ultrasonic sensor;

[0033] Figure 4 This diagram shows the state in which a PCB assembly is inserted into the housing from the rear side to form an electrical connection between the PCB assembly and the connector pins and lead pins of the housing through a press fit.

[0034] Figure 5 This diagram illustrates the process of inserting a PCB assembly into a housing to form an electrical connection between the PCB assembly and the housing's connector pins and lead pins through press fitting.

[0035] Figure 6 This diagram shows the state in which the lead pins are assembled to the housing from the rear side;

[0036] Figure 7 It is a perspective view showing the assembled state inside the housing;

[0037] Figure 8 It shows Figure 6 A diagram of one of the lead pins;

[0038] Figure 9 This diagram shows the states in which the wiring is soldered to the lead pins;

[0039] Figure 10 This is a diagram illustrating the bending of the wiring that is soldered to the lead pin;

[0040] Figure 11This diagram illustrates the process of laser welding wiring to a piezoelectric element.

[0041] Figure 12 This is a cross-sectional diagram illustrating the watertight structure formed between the unit shell and the outer shell through the rubber cap and the front cover;

[0042] Figure 13 It shows Figure 12 An exploded view of the constituent elements along the forward / backward direction; and

[0043] Figure 14 This is a flowchart illustrating a method for manufacturing an ultrasonic sensor according to an exemplary embodiment of the present invention. Detailed Implementation

[0044] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Regardless of the reference numerals in the drawings, the same or similar elements are indicated by the same reference numerals, and redundant descriptions are omitted.

[0045] The suffixes “module” and “unit” used in this article are for the convenience of description and are therefore interchangeable, without any distinguishing meaning or function.

[0046] In the following description of embodiments of the present invention, detailed descriptions of well-known functions and configurations included herein will be omitted where such descriptions may obscure the subject matter of the embodiments. Furthermore, embodiments of the present invention will be more clearly understood with reference to the accompanying drawings, and the embodiments of the present invention should not be limited by the drawings. It should be understood that all modifications, equivalents, and substitutions that do not depart from the spirit and scope of the present invention are included in the present invention.

[0047] It should be understood that although the terms "first," "second," etc., may be used in this document to describe various elements, these elements should not be limited by these terms. These terms are only used to distinguish elements from one another.

[0048] When one element is “connected” or “linked” to another element, it should be understood that the element can be directly connected or linked to the other element, or that another element can exist between them. Conversely, when one element is “directly connected” or “directly linked” to another element, it should be understood that there are no other elements between them.

[0049] Unless otherwise expressly used, singular expressions include plural meanings.

[0050] In this specification, the terms "comprising," "including," etc., are intended to indicate the presence of features, numbers, steps, operations, elements, parts, or combinations thereof, and do not exclude other features, numbers, steps, operations, elements, parts, or any combination thereof, or any additions thereof.

[0051] Furthermore, the term "unit" or "control unit" used in specific terms such as motor control unit (MCU) and hybrid control unit (HCU) is only a term widely used to specify a controller for controlling a specific function of a vehicle, and therefore does not mean a general-purpose functional unit.

[0052] The controller may include a communication device configured to communicate with another controller or sensor to control the functions performed therethere, a memory configured to store an operating system, logic commands, input / output information, etc., and at least one processor configured to perform discrimination, calculation, determination, etc., required to control the functions to be performed.

[0053] Reference Figures 1 to 13 An ultrasonic sensor according to an exemplary embodiment of the present invention is shown. The ultrasonic sensor is configured by including the following items: a piezoelectric element 1; a housing 3 configured to support the piezoelectric element 1, the piezoelectric element 1 being engaged to the front of the housing 3 inside the housing 3, the housing 3 having an opening at its rear; a printed circuit board (PCB) assembly 5 electrically connected to the piezoelectric element 1; a housing 7 coupled to the opening of the housing 3 while housing the PCB assembly 5 therein, and the housing 7 being configured to seal the space required for the electrical connection between the piezoelectric element 1 and the PCB assembly 5 in the housing 3; a filler 9, which fills the space required for the electrical connection between the piezoelectric element 1 and the PCB assembly 5 after the electrical connection between the piezoelectric element 1 and the PCB assembly 5 is completed; and a rear cover 11 configured to seal the rear opening formed in the housing 7 to allow insertion of the PCB assembly 5.

[0054] In addition, the PCB assembly 5 is installed to divide the interior of the housing 7 into a space connected to the unit housing 3 and a space connected to the rear cover 11, so that these spaces are isolated from each other.

[0055] In other words, in the ultrasonic sensor according to an exemplary embodiment of the present invention, the piezoelectric element 1 is coupled to the unit housing 3 to transmit and receive ultrasonic waves, and the housing 7 is divided into a front and a rear portion by the PCB assembly 5. Filler 9 fills the interior of the front portion of the housing 7, thus configuring the ultrasonic sensor to minimize residual moisture during its assembly. Furthermore, the rear opening of the housing 7 for assembling the PCB assembly 5, etc., is sealed by a rear cover 11, thereby ensuring both aesthetics and stable and reliable waterproof performance and sensing performance of the ultrasonic sensor.

[0056] Preferably, an application-specific integrated circuit (ASIC) is disposed on the surface of the PCB assembly 5 facing the unit housing 3, and a circuit element is disposed on the surface of the PCB assembly 5 facing the rear cover, the circuit element having a volume that protrudes from the PCB assembly 5 and is larger than the volume of the ASIC.

[0057] Specifically, an empty space is formed between the PCB assembly 5 and the back cover 11, and circuit elements with relatively large volumes (e.g., capacitors, inductors, etc.) are arranged on the side of the PCB assembly 5 facing the back cover 11, as described above, thereby minimizing the volume of the space and thus minimizing the moisture remaining in the sensor during sensor assembly.

[0058] Preferably, the back cover 11 is made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm, and is joined to the housing 7 by laser welding.

[0059] For example, engineering plastics such as PBT / PET+GF30 can be used for the back cover 11. In this case, the back cover 11 can be configured to have a thickness of about 1 mm, such that its laser transmittance is 50% or greater, so that it can be reliably coupled to the housing 7 by laser welding.

[0060] When the back cover 11, configured as described above, is coupled to the housing 7 by laser welding, sufficient welding strength can be ensured, which can greatly improve the waterproof performance and durability of the ultrasonic sensor.

[0061] A connector 13 electrically connected to the outside is formed in the housing 7, such that the connector 13 is integrated with the housing 7. The connector pins 15 of the connector 13 are insert-molded in the housing 7 such that the end of the connector pins 15 connected to the PCB assembly 5 protrudes parallel to the rear cover 11.

[0062] In other words, since the connector 13 is formed at the housing 7 to integrate with the housing 7, the connector 13 can be manufactured simultaneously with the injection molding of the housing 7. Therefore, not only can costs be reduced, but defects such as moisture ingress can also be prevented in the assembly structure of the housing 7 and the connector 13.

[0063] In addition, preferably, connector 13 is formed as a waterproof connector, thereby maximizing waterproofness.

[0064] Simultaneously, lead pin 17 is inserted into housing 7 for electrical interconnection between PCB assembly 5 and piezoelectric element 1. Lead pin 17 is inserted into housing 7 such that the end of lead pin 17 connected to PCB assembly 5 protrudes parallel to connector pin 15 toward rear cover 11.

[0065] With the lead pin 17 assembled into the housing 7, as described above, the PCB assembly 5 is connected to the connector pin 15 and the lead pin 17 via press fitting.

[0066] In other words, such as Figure 5As shown, the assembly of PCB assembly 5 and housing 7, as well as the electrical connection of PCB assembly 5 with connector pin 15 and lead pin 17 are achieved simultaneously.

[0067] Therefore, manufacturing processes can be significantly reduced while preventing various quality problems caused by welding processes.

[0068] When the lead pin 17 moves linearly from one side of the rear cover 11 to one side of the unit housing 3 in a forward / backward direction, the lead pin 17 is coupled to the housing 7. In this way, the movement of the lead pin 17 relative to the housing 7 in any direction is restricted.

[0069] In other words, once the lead pin 17 is inserted into the pin insertion groove 19 as it moves in the forward / backward direction, the lead pin 17 is assembled into the housing 7, ensuring a stable and fixed state of the lead pin 17, where movement of the lead pin 17 relative to the housing 7 is restricted in any direction.

[0070] In detail, such as Figures 6 to 8 As shown, each lead pin 17 is configured by including the following items: a limiting portion 21, configured to insert into a corresponding lead insertion groove 19, which is formed in the housing 7 in front of the lead pin 17 at one end of the lead pin 17 being press-fitted in the PCB assembly 5, to limit relative movement of the lead pin 17 in a direction perpendicular to the forward / backward direction; and a press-fit protrusion 23, protruding from the limiting portion 21 in the forward / backward direction to press-fit in the housing 7.

[0071] Additionally, each lead pin 17, after extending from the limiting portion 21 in a forward / backward direction, bends toward the center portion of the opening in the unit housing 3. A limiting protrusion 27 is provided in the housing 7 to limit the opposite sides of the bent portion 25 of each lead pin 17.

[0072] Therefore, when the lead pin 17 is inserted into the lead insertion groove 19 of the housing 7, so that the press-fit protrusion 23 of the lead pin 17 is press-fitted in the housing 7, the press-fit protrusion 23, the limiting part 21 and the bending part 2 are restricted to a state in which they cannot move relative to the housing 7 in any direction.

[0073] The stable and secure constraint of the lead pin 17, as described above, can prevent problems such as pin bending and excessive press-fit pressure during the press-fit coupling of the PCB assembly 5 as described above.

[0074] Wiring 29 is disposed between the other end of each lead pin 17 and the piezoelectric element 1, such that the opposite ends of wiring 29 are coupled to the lead pin 17 and the piezoelectric element 1, respectively. Wiring 29 has at least one bend 31 in its middle portion to prevent wiring 29 from breaking due to the contraction and expansion of filler 9.

[0075] In other words, such as Figure 9 As shown, wiring 29 is pressed onto lead pin 17 and then soldered to lead pin 17, thereby enhancing the bonding strength between lead pin 17 and wiring 29. Because wiring 29 has at least one bent portion 31, as... Figure 10 As shown, the curved portion 31 of the wiring 29 receives the deformation of the wiring 29 caused by the contraction and expansion of the filler 9 after the filler 9 is filled, thereby preventing the wiring 29 from breaking off itself and stably maintaining the interconnection state between the wiring 29 and the piezoelectric element 1 as well as the interconnection state between the wiring 29 and the lead pin 17.

[0076] Therefore, the stable durability of the ultrasonic sensor can be ensured.

[0077] An ultrasonic sensor according to an exemplary embodiment of the present invention further includes a rubber cap 33 inserted between the unit housing 3 and the housing 7, and a front cover 35 assembled around the unit housing 3 to surround the front of the rubber cap 33 and the housing 7.

[0078] The unit housing 3 is made of a metallic material (e.g., aluminum). Since the unit housing 3, together with the piezoelectric element 1 attached thereto, performs the function of transmitting and receiving ultrasonic waves, a connection structure between the unit housing 3 and the housing 7, which is injection molded from plastic resin, is inherently necessary. Therefore, in order to couple the unit housing 3 and the housing 7 while ensuring waterproof performance, a rubber cap 33 and a front cover 35 are provided.

[0079] In other words, the rubber cap 33 forms a basic watertight structure between the unit shell 3 and the housing 7. To ensure the stable installation of the rubber cap 33 as described above, the front cover 35 is coupled to the housing 7 while surrounding the rubber cap 33.

[0080] Reference Figure 12 and Figure 13 The housing 7 has an integrated structure including: a support 37 configured to support the rear end of the unit housing 3 when the rubber cap 33 is inserted between the support 37 and the rear end of the unit housing 3, and to allow the opening of the unit housing 3 to communicate with the interior of the housing 7; and a front end 39 configured to protrude from the outside of the support 37 in a forward direction when surrounded by the front cover 35.

[0081] Furthermore, the rubber cap 33 has an integrated structure comprising: a first sealing protrusion 41 configured to press the inner peripheral surface of the support portion 37 of the housing 7, thereby sealing the inner peripheral surface of the support portion 37; a second sealing protrusion 43 configured to press the inner peripheral surface of the front end 39 of the housing 7, thereby sealing the inner peripheral surface of the front end 39; and a third sealing protrusion 45 configured to press the outer peripheral surface of the unit shell 3, thereby sealing the outer peripheral surface of the unit shell 3.

[0082] Therefore, the third sealing protrusion 45 maximizes the watertightness between the outer peripheral surface of the unit housing 3 and the rubber cap 33, and the second sealing protrusion 43 maximizes the watertightness between the housing 7 and the rubber cap 33.

[0083] Specifically, the enlarged portion 47 with an enlarged cross-section is provided at the rear of the outer peripheral surface of the unit housing 3. The third sealing protrusion 45 is formed at the position where the enlarged portion 47 of the unit housing 3 begins to press. Therefore, the watertight performance can be maximized by the third sealing protrusion 45, while the pressure applied to the sidewall of the unit housing 3 is minimized. Thus, the sensing performance and waterproof performance of the ultrasonic sensor can be enhanced simultaneously.

[0084] At the same time, the first sealing protrusion 41 presses against the inner circumferential surface of the support portion 37 of the housing 7, thereby preventing the filler 9 inside the filling unit housing 3 inside the support portion 37 from seeping into the gap between the rubber cap 33 and the housing 7.

[0085] Therefore, it is possible to prevent the formation of large-sized air bubbles in the filler 9 due to the filler 9 seeping into the gap between the rubber cap 33 and the housing 7. Thus, during the sensing operation of the ultrasonic sensor, it is possible to prevent abnormal waveforms from being generated in the filler 9 as described above.

[0086] For reference, foamed silicone or similar materials can be used for filler 9. Since the size of the bubbles generated by the foaming of filler 9 itself is significantly smaller than the size of the bubbles generated by filler 9 penetrating into the gap between the rubber cap 33 and the housing 7, it will not affect the sensing performance of the ultrasonic sensor.

[0087] Additionally, the front cover 35 may be provided with a press-fit rib 49, which is configured to be press-fitted onto the front of the rubber cap 33. The rubber cap 33 has a press-fit groove 51 configured to receive the press-fit rib 49. Therefore, the front cover 35 keeps the rubber cap 33 in a state where the rubber cap 33 is pressed more firmly and stably against the housing 7 and the unit housing 3.

[0088] In other words, with the front cover 35 pressing the rubber cap 33 against the outer peripheral surface of the unit housing 3 via the inclined surface 53 formed inside the press-fit rib 49, the front cover 35 can be ultrasonically fused to the housing 7 and the rubber cap 33. Therefore, a robust and stable watertight state can be ensured.

[0089] Furthermore, at least one rib 55 is formed at the support portion 37 of the housing 7, such that the rib 55 protrudes toward the front of the rubber cap 33. The rib 55 further enhances the watertightness between the rubber cap 33 and the housing 7.

[0090] Reference Figure 14 This paper illustrates a method for manufacturing an ultrasonic sensor according to an exemplary embodiment of the present invention. The method includes: attaching a piezoelectric element 1 to the front portion of the unit housing 3 inside the unit housing 3 (S10); assembling the unit housing 3 to the front portion of the housing 7 with a rubber cap 33 inserted between the unit housing 3 and the front portion of the housing 7, and welding the front cover 35 to the rubber cap 33 and the front portion of the housing 7 with the front cover 35 surrounding the rubber cap 33 and the front portion of the housing 7 (S20); coupling lead pins 17 with soldered wiring 29 to the housing 7 (S30); soldering the wiring 29 to the piezoelectric element 1 for interconnection between them (S40); injecting filler 9 into the interior of the unit housing with wiring 29 and the interior of the housing 7 (S50); inserting a printed circuit board (PCB) assembly 5 into the housing 7 such that the lead pins 17 and connector pins 15 with inserts formed in the housing 7 are connected to the PCB assembly 5 (S60); and sealing the rear portion of the housing 7 with the PCB assembly 5 inserted by a rear cover 11 (S70).

[0091] When the wiring 29 is soldered to the piezoelectric element 1, the soldering can be achieved by a laser irradiated through the rear opening of the housing 7.

[0092] The filler 9 is injected such that it only fills the space facing the front of the PCB assembly 5. The PCB assembly 5 is inserted into the housing 7 such that the lead pins 17 and the connector pins 15 are electrically interconnected by press-fit.

[0093] The back cover 11 is made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm. The back cover 11 is laser welded to the rear of the housing 7, which is injection molded using plastic resin, and thus seals the housing 7.

[0094] It is evident from the above description that the ultrasonic sensor according to exemplary embodiments of the present invention can provide stable sensing performance and waterproof performance, while being inexpensive and simple to manufacture.

[0095] Although preferred embodiments of the invention have been disclosed for illustrative purposes, those skilled in the art will recognize that various modifications, additions, and substitutions are possible without departing from the scope and spirit of the invention as disclosed in the appended claims.

Claims

1. An ultrasonic sensor, comprising: piezoelectric elements; A unit housing is configured to support the piezoelectric element, which is joined to the front of the unit housing inside the unit housing, the unit housing having an opening at its rear. A printed circuit board (PCB) assembly is electrically connected to the piezoelectric element; A housing, coupled to the opening of the unit housing and housing the PCB assembly therein, and configured to seal the space required for the electrical connection between the piezoelectric element in the unit housing and the PCB assembly; Filler material, filling the space required for the electrical connection between the piezoelectric element and the PCB assembly; and The rear cover is configured to seal the rear opening formed at the housing to allow insertion of the PCB assembly. The PCB assembly divides the interior of the housing into a front portion formed by a space connected to the unit shell and a rear portion formed by a space connected to the rear cover, such that these spaces are isolated from each other. The space formed between the PCB assembly and the back cover is empty. The application-specific integrated circuit (ASIC) is disposed on the surface of the PCB assembly facing the unit housing, and the circuit element is disposed on the surface of the PCB assembly facing the rear cover. The volume of the circuit element protruding from the PCB assembly is greater than the volume of the ASIC protruding from the PCB assembly.

2. The ultrasonic sensor according to claim 1, wherein: The rear cover is made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm; and The rear cover is joined to the housing by laser welding.

3. The ultrasonic sensor according to claim 1, wherein: A connector is formed at the housing, such that the connector is integrated with the housing; and The connector pins of the connector are embedded in the housing, such that the end of the connector pins connected to the PCB assembly protrudes parallel to the rear cover.

4. The ultrasonic sensor according to claim 3, wherein: Lead pins are inserted into the housing for electrical interconnection between the PCB assembly and the piezoelectric element; The lead pin is inserted into the housing such that the end of the lead pin connected to the PCB assembly protrudes parallel to the connector pin toward the rear cover; as well as The PCB assembly is press-fitted to the connector pins and the lead pins.

5. The ultrasonic sensor according to claim 4, wherein, The lead pin is coupled to the housing by its linear movement in a forward / backward direction from one side of the rear cover to one side of the unit housing, such that the movement of the lead pin relative to the housing in any direction is restricted.

6. The ultrasonic sensor according to claim 5, wherein, Each of the said lead pins includes: A limiting portion is configured to insert a pin insertion recess, the pin insertion recess being formed in the housing in front of one end of the lead pin being press-fitted into the PCB assembly, limiting relative movement of the lead pin in a direction perpendicular to the forward / backward direction; and A press-fit protrusion protrudes from the limiting portion in the forward / backward direction to press-fit into the housing.

7. The ultrasonic sensor according to claim 6, wherein: The lead pins bend toward the center portion of the opening in the unit housing after extending from the limiting portion in the forward / backward direction; and A limiting protrusion is provided at the housing to limit the opposite sides of the bent portion of the lead pin.

8. The ultrasonic sensor according to claim 6, wherein: A wiring is disposed between the other end of the lead pin and the piezoelectric element, such that the opposite ends of the wiring are respectively coupled to the lead pin and the piezoelectric element; and The wiring has at least one curved portion in its middle to prevent it from breaking due to the contraction and expansion of the filler.

9. The ultrasonic sensor according to claim 1, further comprising: A rubber cap is inserted between the unit shell and the housing. as well as A front cover, assembled around the unit shell to surround the rubber cap and the front of the shell.

10. The ultrasonic sensor according to claim 9, wherein, The housing has an integrated structure, which includes: A support portion is configured to support the rear end of the unit housing when the rubber cap is inserted between the support portion and the rear end of the unit housing, and to allow the opening of the unit housing to communicate with the interior of the housing; and The front end is configured to protrude forward from the outside of the support while being surrounded by the front cover.

11. The ultrasonic sensor according to claim 10, wherein, The rubber cap has an integrated structure, which includes: A first sealing protrusion is configured to press against the inner peripheral surface of the support portion of the housing to seal the inner peripheral surface of the support portion; A second sealing protrusion is configured to press against the inner peripheral surface of the front end of the housing, sealing the inner peripheral surface of the front end; and The third sealing protrusion is configured to press against the outer peripheral surface of the unit housing to seal the outer peripheral surface of the unit housing.

12. The ultrasonic sensor according to claim 11, wherein: An enlarged portion with an enlarged cross-section is provided at the rear of the outer peripheral surface of the unit shell; and The third sealing protrusion is formed in the region where the enlarged portion of the unit housing begins to be pressed.

13. The ultrasonic sensor according to claim 11, wherein: The front cover is provided with a press-fit rib, the press-fit rib being configured to be press-fitted onto the front portion of the rubber cap; and The rubber cap is formed with a press-fit groove configured to receive the press-fit rib.

14. The ultrasonic sensor according to claim 13, wherein, With the front cover pressing the rubber cap against the outer peripheral surface of the unit housing via an inclined surface formed inside the press-fit rib, the front cover is ultrasonically welded to the housing and the rubber cap.

15. The ultrasonic sensor according to claim 10, wherein, At least one rib is formed at the support portion of the housing, such that the rib protrudes toward the front of the rubber cap.

16. A method for manufacturing an ultrasonic sensor, the method comprising: The piezoelectric element is attached to the front of the unit housing from inside the unit housing; The unit shell is assembled to the front of the housing, a rubber cap is inserted between the unit shell and the front of the housing, and a front cover is welded to the rubber cap and the front of the housing such that the front cover surrounds the rubber cap and the front of the housing; The wired leads are coupled to the housing. The wiring is soldered to the piezoelectric element; The filler is injected into the interior of the unit housing and the interior of the housing, where the wiring is provided; Inserting the printed circuit board (PCB) assembly into the housing such that the lead pins and connector pins with inserts formed in the housing are connected to the PCB assembly; and The rear of the housing containing the PCB assembly is sealed by a rear cover. The PCB assembly divides the interior of the housing into a front portion formed by a space connected to the unit shell and a rear portion formed by a space connected to the rear cover, such that these spaces are isolated from each other. The space formed between the PCB assembly and the back cover is empty. The application-specific integrated circuit (ASIC) is disposed on the surface of the PCB assembly facing the unit housing, and the circuit element is disposed on the surface of the PCB assembly facing the rear cover. The volume of the circuit element protruding from the PCB assembly is greater than the volume of the ASIC protruding from the PCB assembly.

17. The method of claim 16, wherein: The filler is injected such that it fills only the space facing the front of the PCB assembly; and The PCB assembly is inserted into the housing such that the lead pins and the connector pins are electrically interconnected by press-fit.

18. The method according to claim 16, wherein, The back cover is made of engineering plastic with a laser transmittance of 50% or greater at a thickness of 1 mm, and the back cover is laser welded to the rear of the housing, which is injection molded using plastic resin, thereby sealing the housing.

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