Ultrasonic sensor having compressively deformed spring resiliently attaching sensor body and bezel

An ultrasonic sensor has a sensor body and a bezel having a metal spring attached on a side wall thereof for installation on a vehicle component. A free end of the metal spring is positioned to protrude from a through hole of the side wall, is pressed by a portion of the sensor body that is inserted in a hollow space of the bezel, and is pushed back by an opening face of the sensor body. In this manner, the bezel is firmly attached on the component and the sensor body is firmly attached on the bezel.

CROSS REFERENCE TO RELATED APPLICATION

This application is based on and claims the benefit of priority of Japanese Patent Application No. 2006-71288 filed on Mar. 15, 2006, and of Japanese Patent Application No. 2006-71289 filed on Mar. 15, 2006, the disclosure of which is incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates to an ultrasonic sensor having an ultrasonic transducer that includes a piezoelectric element.

BACKGROUND INFORMATION

A conventional ultrasonic sensor has, for example, a sensor body with an ultrasonic transducer installed therein attached to the bumper of a vehicle. Ultrasonic waves are generated by the ultrasonic transducer and, by receiving reflection waves of the ultrasonic waves, an obstacle existing near the bumper is detected.

FIG. 17is a partial cross section showing a structure of fixing the conventional ultrasonic sensor100to a bumper101. As shown in the diagram, a sensor body102of the ultrasonic sensor100has a circular column shape. By inserting the sensor body102in a circular hole101aformed in the bumper101from the outside of the bumper101, the sensor body102is fixed to the bumper101. More practically, a flange102ais provided at the rear end in the direction of insertion to the bumper101in the sensor body102, and a V-shaped metal spring103is provided around the outer periphery of the sensor body102. Consequently, when the sensor body102is inserted in the hole101ain the bumper101, in a state where movement in the insertion direction of the sensor body102is regulated by the flange102a, the widening force in the radial direction of the sensor body102generated by the metal spring103is applied to the wall face constructing the hole101aof the bumper101, so that the sensor body102is firmly fixed to the bumper101(refer to, for example, U.S. Pat. No. 6,759,950).

In recent years, the ultrasonic sensor is becoming intelligent, and a circuit board on which not only an ultrasonic transducer but also a signal processing circuit and the like are formed is being housed in the sensor body. The sensor body is accordingly enlarged, and a problem occurs such that the sensor body cannot be inserted in the hole in the bumper from the outside of the bumper. Therefore, by a structure different from a conventional structure, the ultrasonic sensor has to be attached to the bumper.

To address the above-described problem, the inventors of the present invention have devised a structure in which a bezel (cover) formed in a cylindrical shape and having a flange at its one end is provided. The bezel is fixed by being inserted from the outside of the bumper into a hole in the bumper. After that, by inserting a circular column portion in which an ultrasonic transducer is disposed in the sensor body into the hollow in the bezel from the inside of the bumper (that is, in the direction opposite to the insertion direction of the bezel to the hole in the bumper), the sensor body is fixed to the bumper via the bezel.

In the case of such a structure, the large sensor body has to be held by the bezel functioning as a fixing member. Consequently, the bezel has to be firmly fixed to the bumper, and the sensor body has to be firmly fixed to the bezel.

The above-described problem also arises when the ultrasonic sensor is attached to a part of the vehicle that is different from a bumper in a vehicle body.

SUMMARY OF THE DISCLOSURE

In view of the problems, an object of the present disclosure is to provide an ultrasonic sensor having a bezel that is firmly attached to a vehicle part for firmly holding a body part of the ultrasonic sensor when the body part of the ultrasonic sensor is attached to the vehicle part such as a bumper or the like.

The ultrasonic sensor of the present disclosure includes a bezel in a pipe shape with an opening on one end and a hollow space housed therein, a sensor body having an insertion portion with an ultrasonic transducer disposed therein, and a spring. A side wall of the bezel has an opening of a through hole that connects an outside of the bezel and the hollow space, and the side wall of the bezel has the spring disposed at a position of the through hole. When the bezel is inserted into a hole portion of a vehicle component from an outside of the component before having the insertion portion of the sensor body being inserted from an inside of the component into the hollow space of the bezel, the spring is compressively deformed by an outer wall of the insertion portion and a wall face of the hole portion, thereby generating a reactive force that resiliently attaches the sensor body and the bezel on the wall face of the hole portion.

In this case, a metal spring may be used as the spring, and a free end of the metal spring may protrude from the through hole to apply the reactive force to the wall face of the hole portion.

Further, a flange may be disposed on the bezel at its rear end relative to the insertion direction into the component, and the flange may contribute to the attachment of the bezel on the component.

Furthermore, the flange may define a space between an outer face of the component, and the spring may protrude from the outer face into the space. In this manner, the spring may effectively contribute to the attachment of the bezel on the component.

DETAILED DESCRIPTION

Embodiments of the present invention will be described below with reference to the drawings. In the following embodiments, the same reference numerals are assigned to parts which are the same or equivalent to each other in the drawings.

First Embodiment

An ultrasonic sensor according to a first embodiment of the invention will be described. An ultrasonic sonar of the present embodiment is attached to, for example, a bumper of a vehicle and is used as a back sonar or a corner sonar.

FIG. 1is a side view showing a state in which an ultrasonic sensor1of the embodiment is attached to a bumper2. InFIG. 1, only the bumper2is shown as a section.

As shown in the diagram, the ultrasonic sensor1is fixed in a hole2ain the bumper2. The ultrasonic sensor1has a configuration including the sensor body3and a bezel4. The bezel4is inserted into the hole2ain the bumper2from the outside of the bumper2(i.e., from the left side of the drawing) and, after that, the sensor body3is inserted into the hollow in the bezel4from the inside of the bumper2(i.e., from the right side of the drawing), thereby fixing the ultrasonic sensor1to the bumper2.

The detailed structure of the sensor body3and the bezel4will be described below.

FIGS. 2A to 2Dare front view, right side view, top view, and rear view, respectively, of the sensor body3.FIG. 3is a cross section of the sensor body3, which is taken along a line III-III inFIG. 2A.

In the sensor body3, as shown inFIGS. 2A to 2DandFIG. 3, an ultrasonic transducer10and a circuit board20are integrally enclosed in a case30.FIG. 4is a cross section of the ultrasonic transducer10provided for the sensor body3. As shown inFIG. 4, the ultrasonic transducer10has a housing11, a piezoelectric element12, a spacer13, a base14, and a connection pin15.

The housing11is made of a conductive material (a metal material or an insulating material having a surface on which a conductive film is formed). The housing11has a bottomed cylindrical shape and an internal space16is formed in the housing11. The piezoelectric element12is adhered to the inner face of a bottom11aof the housing11, and the outer surface of the bottom11aserves as a vibration face1b. In the embodiment, aluminum is used as the conductive material, and the vibration face11bhas a circular shape.

The piezoelectric element12is made of piezoelectric ceramics (for example, lead zirconate titanate) and is provided with electrodes (not shown) on its front surface and rear surface. One of the electrodes of the piezoelectric element12is electrically connected to one of the connection pins15of the pair via a lead17a. The other electrode of the piezoelectric element12is adhered to the bottom11aof the housing11by, for example, a conductive adhesive, connected to a lead17bvia the housing11made of the conductive material and, after that, electrically connected to the other connection pin15. The internal space16of the housing11is filled with felt or silicon so that unnecessary vibrations transmitted from the vibration surface to the connection pins15are suppressed.

The spacer13is disposed between the opening in the housing11and the base14. The spacer13is an elastic member for suppressing transmission of the unnecessary vibrations generated in a cylindrical portion11cof the housing11in association with vibrations of the bottom11aof the housing11to the base14to which the connection pins15are fixed. The spacer13is made of, for example, silicon rubber. Although the configuration of disposing the space13is used in the present embodiment, a configuration having no spacer13can be also employed.

The base14is fixed to the housing11by being fit in the peripheral surface on the opening side of the housing11. The base14is made of an insulating material such as a synthetic resin (for example, ABS resin). To the base14, a protection portion18for covering the connection pins15is provided so as to project to the circuit board20side. The connection pins15are disposed so as to penetrate the protection portion18. By insert-molding the connection pins15at the time of forming the base14, a part of the connection pins15is buried and fixed in the base14.

Each of the connection pins15is mainly made of a conductive material such as copper and is constructed by a rod member having a thickness of, for example, 0.5 mmφ (i.e., having the diameter of 0.5 mm).

Further, the ultrasonic transducer10has a foam elastic member19made of, for example, foam silicon. The foam elastic member19is used to suppress transmission of vibration to the base14, and the connection pins15are disposed so as to penetrate also the foam elastic member19.

The housing11, spacer13, base14, and foam elastic member19are adhered to each other with an adhesive (such as silicon adhesive), thereby forming the ultrasonic transducer10as an integral structure.

By assembling the ultrasonic transducer10constructed as described above together with the circuit board20into the hollow case30made of the synthetic resin, the ultrasonic sensor1is constructed.

The case30is constructed by a hollow rectangular-parallelepiped shape. The case30has a guide31for positioning the connection pines15in a connection position in the circuit board20. The guide31is constructed by a plate member which partitions the internal space of the case30into a space in which the ultrasonic transducer10is disposed and a space in which the circuit board20is disposed. The guide31has a positioning hole31ainto which the connection pins15and the protection portion18are inserted.

One face (the upper face in the drawing sheet inFIG. 3) of the case30is an open face32whose top face shape is a circular shape. By inserting the ultrasonic transducer10into the open face32, the ultrasonic transducer10is assembled in the case30. The outer peripheral surface of the ultrasonic transducer10is covered with a cylindrical elastic member33, and a foam elastic member34as an elastic member that suppresses vibrations is disposed below the base14in the ultrasonic transducer10. In a state in which the ultrasonic transducer10is assembled in the case30, the connection pins15are inserted in the positioning hole31ain the guide31, and the tip portions of the connection pins15are inserted in through holes21formed in the circuit board20. The tip portions of the connection pins15and the through holes21are electrically connected to each other by soldering or the like.

The vibration face11bof the ultrasonic transducer10is exposed from the open face32of the case30and ultrasonic waves generated by the ultrasonic transducer10are transmitted to the outside of the case30.

The cylindrical elastic member33is made of silicon rubber and is adhered to the outer peripheral surface of the ultrasonic transducer10(the surface of the cylindrical portion11cof the housing11) and the bottom face of the ultrasonic transducer10in order to suppress transmission of unnecessary vibrations from the ultrasonic transducer10to the case30.

Like the foam elastic member19disposed in the housing11of the ultrasonic transducer10, the foam elastic member34is made of silicon foam, and the connection pins15and the protection portion18are disposed so as to penetrate the foam elastic member34. There is a cut portion in the foam elastic member34, and the protection portion18can be inserted in the cut portion. The ultrasonic transducer10(base14), the cylindrical elastic member33, and the foam elastic member34are fixedly adhered to each other by a silicone adhesive.

The hollow in which the circuit board20is disposed in the case30partitioned by the guide31is filled with a moisture-proof member35. As the moisture-proof member35, for example, a silicone resin or urethane resin can be applied. In the present embodiment, a silicone resin is applied. As shown inFIG. 3, an external output terminal36for output from the circuit board20to the outside is provided, and one end side of the external output terminal36is exposed from a connector37formed in one face of the case30.

Further, as shown inFIGS. 2A to 2D, a lance38is provided on the top face (the upper side of the drawing inFIG. 2A) of the case30, and a receiving part39is provided in the bottom face (the lower side of the drawing inFIG. 2A) of the case30.

The lance38is a nail-shaped retaining part formed so as to project from the top face of the case30in the same direction as that of the open face32, and is used for fixation to the bezel4. More practically, the lance38has a rod part38aand a nail part38b. The rod part38ais projected from the top face of the case30in the same direction as that of the open face32, and the nail part38bis formed on the open face32side in the tip position of the rod part38a.

A receiving part39is a frame-shaped retaining part provided so as to project downward from the bottom face of the case30, and is also used for fixation to the bezel4. More practically, as shown inFIGS. 2A and 2D, the receiving part39has a square frame shape when viewed from the projection direction of the open face32. A snap fit4bprovided for the bezel4which will be described later can be inserted in the hole in the receiving part39.

The portion of the ultrasonic transducer10and the open face32, in the sensor body3constructed as described above, that is, the cylindrical projected portion of the case30is an insertion portion to be inserted in the bezel4. Therefore, the projection direction of the open face32is the insertion direction of the sensor body3to the bezel4.

FIGS. 5A,5B,5C,5D, and5E are a front view, left side view, rear view, top view, and bottom view, respectively, of the bezel4.FIG. 6is a partially enlarged cross section of the bezel4, taken along a line VI-VI ofFIG. 5C.

As shown inFIGS. 5A to 5E, the bezel4is constructed by an almost cylindrical member made of a material such as a resin or the like. A flange4awhose diameter is partly enlarged is formed at one end of the bezel4. The shape and size of the hollow of the bezel4correspond to those of the open face32in the sensor body3. In the hollow, the open face32and the ultrasonic transducer10are inserted.

A snap fit4bis provided for the under face of the bezel4. The snap fit4bfunctions as a nail-shaped retaining part. As shown inFIGS. 2A and 5B, by inserting a nail4cformed at the tip of the snap fit4binto the hole in the receiving part39of the case30, the snap fit4bis retained by the receiving part39. With the configuration described above, the bezel4and the sensor body3are fixed more firmly. Slits4jare formed on both sides of the nail4cas shown inFIG. 5E, so that the nail4cdisposed between the slits4jis susceptible to stress deformation.

A retaining hole4dis formed in the top face of the bezel4. The retaining hole4dis a hole having a square shape when viewed from front, in which the nail38bof the lance38provided for the case30is to be inserted. As shown inFIGS. 2B and 5D, when the nail38bof the lance38is inserted in the retaining hole4d, the nail38bis retained by the inner wall of the retaining hole4d. With the configuration described above, firmness of the fixation between the bezel4and the sensor body3is increased.

Retaining nails4eare provided in positions on both right and left sides of the bezel4in the outer peripheral surface of the bezel4. The retaining nails4eare formed in positions that takes the thickness of the bumper2into consideration. Specifically, the retaining nails4eare provided in positions apart from the end face of the flange4aby the amount of the thickness of the bumper2or slightly larger. The retaining nails4eare provided to prevent the bezel4from coming off from the bumper2. After attaching the bezel4to the bumper2, at the time of inserting the open face32of the case30in the sensor body3into the bezel4, a force is applied in the direction that the bezel4comes off from the bumper2. Consequently, when the bezel4is inserted in the bumper2, the retaining nails4eare retained by the end face of the bumper2, so that the bezel4can be prevented from coming off from the bumper2. As shown inFIG. 5B, the slits4fare provided on both sides of each of the retaining nails4eand the rod part between the slits4fis susceptible to stress-deformation, so that the retaining nails4edo not hinder insertion at the time of attachment to the bumper2.

Further, in the bezel4, a plurality of (in the present embodiment, four) grooves4gare formed at equal intervals with respect to the center of the bezel4. As shown inFIG. 6, through holes4hand4iin two positions arranged along the center axis of the bezel4are formed in each of the grooves4g. In addition, a metal spring5is disposed along each of the grooves4g. In this case, the through holes4hand4imay be formed as one hole. However, a wall may be provided between the holes4hand4iso as to increase a load from the metal spring5. That is, when a tip portion of the metal spring5is held by the wall of the hole4h, the metal spring5is prevented from being forced into the through hole4h, thereby enabling an increase of the resilient force of the metal spring5.

More practically, the metal spring5is formed by bending a thin rod-shaped metal. The metal spring5has a nail5aobtained by bending one end of the rod-shaped metal in a nail shape, a U-shaped part5bbent in a U shape in accordance with the shape of the end of the opening of the bezel4, a projection part5cprojected in the radial direction from the outer peripheral surface of the bezel4, and a folded part5dobtained by folding the other end of the rod-shaped metal to the nail5aside. When the nail5aof the metal spring5is inserted from the open end of the bezel4until the U-shaped part5bcomes into contact with the open end of the bezel4, the nail5aenters the through hole4iand is retained by the end face of the through hole4i, thereby fixing the metal spring5.tothe bezel4. Consequently, the side fixed to the bezel4of the metal spring5, that is, the U-shaped part5bserves as the fixing end, and the folded part5dserves as the free end, thereby playing the spring function.

That is, at the free end of the metal spring5, the side faces of the bumper2and the open face32in the sensor body3come into contact with the metal spring5. The elastic force of the metal spring5is applied in the direction of spreading in the radial direction of the bezel4to the bumper2. The elastic force of the metal spring5is applied in the contraction direction in the radial direction of the bezel4to the open face32in the sensor body3.

Consequently, in the structure of fixing the sensor body3to the bumper2via the bezel4, the bezel4can be firmly fixed to the bumper2, and the sensor body3can be firmly fixed to the bezel4. Thus, the ultrasonic sensor1can be firmly fixed to the bumper2.

Next, a state where the ultrasonic sensor1is attached to the bumper2will be described.FIG. 7is an illustration showing a state before attachment of the ultrasonic sensor1to the bumper2.

As shown inFIG. 8, first, the bezel4is inserted from one side of the bumper2, that is, the outer side of the bumper2into the hole2ain the bumper2until the retaining nail4efits in the bumper2. The open end of the hole2ain the bumper2and the inclined portion of the projection part5cin the metal spring5come into contact with each other.FIG. 8is a partially enlarged cross section showing the state at this time.

As shown in the illustration inFIG. 8, when the bezel4is inserted in the hole2ain the bumper2, the metal spring5is elastically deformed by the open end of the hole2ain the bumper2, and the folded part5das a free end of the metal spring5enters the through hole4hthereby being projected out from the inner wall face of the bezel4.

After that, as shown by the arrow inFIG. 7, the open face32and the ultrasonic transducer10in the sensor body3are inserted in the hollow of the bezel4from the other side of the bumper2, that is, from the inside of the bumper2. In this manner, a tip end of the snap fit4benters the hole in the receiving part39, and the nail4cbetween the slits4jis inserted and engaged with the receiving part39due to a restoration from a deformation by the inner wall of the receiving part39after the nail4cis elastically deformed by the inner wall of the receiving part39for insertion. In addition, the lance38engages the retaining hole4dby having the nail38bentered in the retaining hole4dafter deformation by abutment to the outer wall of the bezel4for insertion.

Further, the external wall face of the open face32and a portion of the free end of the metal spring5that protrudes toward the inner wall of the bezel4after entering the through hole4hcome into contact with each other.FIG. 9shows a partially enlarged cross-sectional view of the bezel4having the open face32of the sensor body3being inserted in a hollow of the bezel4.

As shown in the illustration, the free end of the metal spring5comes into contact with the external wall face of the open face32, so that the free end is pushed back in the expanding direction in the radial direction of the bezel4. Consequently, in the free end of the metal spring5, the bumper2and the side face of the open face32in the sensor body3come into contact with the metal spring5. To the bumper2, the elastic force of the metal spring5is applied in the expanding direction in the radial direction of the bezel4. The elastic force of the metal spring5is applied in the contracting direction of the radial direction of the bezel4to the open face32in the sensor body3. That is, the free end of the metal spring5is elastically compressed between the external wall face of the open face32and the wall face of the hole2aof the bumper2. By elastic reaction force accompanying the compressive deformation of the metal spring5, the sensor body3and the bezel4are fixed to the wall face of the hole2a.

In this manner, in the structure in which the sensor body3is fixed to the bumper2via the bezel4, the bezel4can be firmly fixed to the bumper2, and the sensor body3can be firmly fixed to the bezel4. Thus, the ultrasonic sensor1can be firmly fixed to the bumper2.

Second Embodiment

FIGS. 10A,10B,10C,10D,10E are a front view, left-side view, rear view, top view, bottom view, respectively, of the bezel4.FIG. 11is a partially enlarged cross section of the bezel4, taken along a line XI-XI ofFIG. 10C.

As shown inFIGS. 10A to 10E, the bezel4is constructed by an almost cylindrical member made of a material such as a resin softer than a metal. A flange4awhose diameter is partly enlarged is formed at one end of the bezel4. The shape and size of the hollow of the bezel4correspond to those of the open face32in the sensor body3. In the hollow, the open face32and the ultrasonic transducer10are inserted.

The flange4aof the bezel4has a cross section in an arc shape, and a tip of the flange4ahas a contact with the bumper2. More practically, a radially farthest portion of the flange4athat extends outwardly from an axis of the cylindrical shape touches the bumper2on its surface. In this manner, a space between broken lines A and B inFIG. 11is reserved in an area that is defined by the arc shape of the flange4aand the surface of the bumper2when the tip of the flange4atouches the surface of the bumper. The amount of protrusion, i.e., the distance between the lines A and B in a horizontal direction inFIG. 11, is determined according to the thickness of the bumper2, and is preferably determined as an amount that is equal to or is greater than, for example, the dispersion of the thickness of the bumper2where the bezel4is fixed.

A snap fit4bis provided for the under face of the bezel4. The snap fit4bfunctions as a nail-shaped retaining part. As shown inFIGS. 2A and 5B, by inserting a nail4cformed at the tip of the snap fit4binto the hole in the receiving part39of the case30, the snap fit4bis retained by the receiving part39. With the configuration described above, the bezel4and the sensor body3are fixed more firmly. In addition, slits4jare formed on both sides of the nail4c, so that the nail4cdisposed between the slits4jis susceptible to stress deformation.

A retaining hole4dis formed in the top face of the bezel4. The retaining hole4dis a hole having a square shape when viewed from front, in which the nail38bof the lance38provided for the case30is to be inserted. As shown inFIGS. 2B and 10D, when the nail38bof the lance38is inserted in the retaining hole4d, the nail38bis retained by the inner wall of the retaining hole4d. With the configuration described above, firmness of the fixation between the bezel4and the sensor body3is increased.

Retaining nails4eare provided in positions on both right and left sides of the bezel4in the outer peripheral surface of the bezel4. The retaining nails4eare formed in positions that takes the thickness of the bumper2into consideration. Specifically, the retaining nails4eare provided in positions apart from the end face of the flange4aby the amount of the thickness of the bumper2or slightly larger. The retaining nails4eare provided to prevent the bezel4from coming off from the bumper2. After attaching the bezel4to the bumper2, at the time of inserting the open face32of the case30in the sensor body3into the bezel4, a force is applied in the direction that the bezel4comes off from the bumper2. Consequently, when the bezel4is inserted in the bumper2, the retaining nails4eare retained by the end face of the bumper2, so that the bezel4can be prevented from coming off from the bumper2. As shown inFIG. 10B, the slits4fare provided on both sides of each of the retaining nails4eand the rod part between the slits4fis susceptible to stress-deformation, so that the retaining nails4edo not hinder insertion at the time of attachment to the bumper2.

Further, in the bezel4, a plurality of (in the present embodiment, four) grooves4gare formed at equal intervals with respect to the center of the bezel4so as to extend from the outer face of the side wall of the bezel4to the inner face. As shown inFIG. 11, through holes4hand4iin two positions arranged along the center axis of the bezel4are formed in each of the grooves4g. In addition, a metal spring5is disposed along each of the grooves4g. In this case, the through holes4hand4imay be formed as one hole. However, a wall may be provided between the holes4hand4iso as to increase a load from the metal spring5. That is, when a tip portion of the metal spring5is held by the wall of the hole4h, the metal spring5is prevented from being forced into the through hole4h, thereby enabling an increase of the resilient force of the metal spring5.

The metal spring5is formed by bending a thin rod-shaped metal. The metal spring5has a nail5aobtained by bending one end of the rod-shaped metal in a nail shape, a U-shaped part5bbent in a U shape in accordance with the shape of the end of the opening of the bezel4, a projection part5cprojected in the radial direction from the outer peripheral surface of the bezel4, and a folded part5dobtained by folding the other end of the rod-shaped metal to the nail5aside. When the nail5aof the metal spring5is inserted from the open end of the bezel4until the U-shaped part5bcomes into contact with the open end of the bezel4, the nail5aenters the through hole4iand is retained by the end face of the through hole4i, thereby fixing the metal spring5to the bezel4. Consequently, the side fixed to the bezel4of the metal spring5, that is, the U-shaped part5bserves as the fixing end, and the folded part5dserves as the free end, thereby playing the spring function.

More practically, at the free end of the metal spring5, the side faces of the bumper2and the open face32in the sensor body3come into contact with the metal spring5. The elastic force of the metal spring5is applied in the direction of spreading in the radial direction of the bezel4to the bumper2. The elastic force of the metal spring5is applied in the contraction direction in the radial direction of the bezel4to the open face32in the sensor body3.

Consequently, in the structure of fixing the sensor body3to the bumper2via the bezel4, the bezel4can be firmly fixed to the bumper2, and the sensor body3can be firmly fixed to the bezel4. Thus, the ultrasonic sensor1can be firmly fixed to the bumper2.

In the present embodiment, when the bezel4is inserted into the hole2aof the bumper, the tip of the folded part5das a free end, i.e., a portion of the folded part5dat the most flange5aside, enters the space between the flange5aand the surface of the bumper2, thereby protruding from the bumper2toward an outside of the bumper2.

In this manner, even when a contacting portion of the metal spring5on the wall of the hole2aof the bumper2is changed, the metal spring5is resiliently deformed in the same manner so that the bezel4is fixed on the bumper2by the same amount of the resilient force from the spring5.

Next, a state where the ultrasonic sensor1is attached to the bumper2will be described.FIG. 12is an illustration showing a state before attachment of the ultrasonic sensor1to the bumper2.

As shown inFIG. 12, first, the bezel4is inserted from one side of the bumper2, that is, the outer side of the bumper2into the hole2ain the bumper2until the retaining nail4efits in the bumper2. The open end of the hole2ain the bumper2and the inclined portion of the projection part5cin the metal spring5come into contact with each other.FIG. 13is a partially enlarged cross section showing the state of assembly at this point.

As shown in the illustration inFIG. 13, when the bezel4is inserted in the hole2ain the bumper2, the metal spring5is elastically deformed by the open end of the hole2ain the bumper2, and the folded part5das a free end of the metal spring5enters the through hole4hand is projected out from the inner wall face of the bezel4.

After that, as shown by the arrow inFIG. 12, the open face32and the ultrasonic transducer10in the sensor body3are inserted in the hollow of the bezel4from the other side of the bumper2, that is, the inside of the bumper2. In this manner, the tip end of the snap fit4benters the hole of the receiving part39, thereby engaging the nail4cand the receiving part39when the nail4cbetween the slits4jis pushed back by the inner wall of the receiving part39and is restored by resilience to go into the hole. Further, the lance38engages the retaining hole4dwhen the rod part38aof the lance38is pushed back for having the nail38bto be placed in the retaining hole4d.

Further, the outer wall of the open face32and a portion of the free end of the metal spring5that enters the through hole4hin the bezel4come into contact with each other.FIG. 14shows a partially enlarged cross-sectional view of the bezel4having the open face32of the sensor body3being inserted in a hollow thereof.

As shown in the illustration, the free end of the metal spring5comes into contact with the external wall face of the open face32, so that the free end is pushed back in the expanding direction in the radial direction of the bezel4. Consequently, in the free end of the metal spring5, the bumper2and the side face of the open face32in the sensor body3come into contact with the metal spring5. To the bumper2, the elastic force of the metal spring5is applied in the expanding direction in the radial direction of the bezel4. The elastic force of the metal spring5is applied in the contracting direction of the radial direction of the bezel4to the open face32in the sensor body3. That is, the free end of the metal spring5is elastically compressed between the outer wall face of the open face32and the wall face of the hole2aof the bumper2. By elastic reaction force accompanying the compressive deformation, the sensor body3and the bezel4are fixed to the wall of the hole2a.

In this manner, in the structure in which the sensor body3is fixed to the bumper2via the bezel4, the bezel4can be firmly fixed to the bumper2, and the sensor body3can be firmly fixed to the bezel4. Thus, the ultrasonic sensor1can be firmly fixed to the bumper2.

The ultrasonic sensor1of the present embodiment having the space between the flange4aand the bumper2with the tip of the free end of the metal spring5inserted therein has the advantage in the following manner.

That is, the structure of the metal spring5in the present embodiment inserts the folded part5dinto the space between the flange4aand the bumper2, thereby making the contact point between the metal spring5and the wall of the hole2ain the bumper closer to the projection part5cof the metal spring5by the amount that is equal to the thickness of the bumper2when the structure is compared with the structure that does not provides the space between the flange4aand the bumper.

Therefore, the resilient force generated by the deformation of the metal spring5in the arrow direction inFIG. 14becomes greater because the amount of the deformation of the metal spring5becomes greater when the contact point between the metal spring5and the wall of the hole2acoming closer to the projection part5chas an increased space for deformation. In other words, the change of the resilient force from the metal spring5according to the change of the thickness of the bumper2becomes smaller relative to the resilient force itself when the ratio of the resilient force to the change increases.

As a result, the bezel4is firmly fixed on the bumper2, thereby enabling a firm fixation of the sensor body3on the bezel4. That is, the ultrasonic sensor1is firmly fixed on the bumper2.

In this manner, insufficiency and/or inappropriateness of the fixation of the bezel4on a vehicle body such as a bumper or the like due to the thickness of the vehicle body where the bezel4is disposed is prevented.

For example, the metal spring5is provided in a shape as shown inFIGS. 15A and 15B. That is, the metal spring5bent at the U-shaped part5bis formed to have a bent portion5ethat enters the through hole4hwith a protrusion5cextended therefrom. The metal spring5shaped in the above-described manner has the same effect as the spring5in the first and the second embodiments.

Further, the arc shape of the flange4amay be replaced with other shapes. For example, as shown inFIG. 16, a rectangular shape of the flange4athat radially outwardly extends from the axis of the bezel4with a wall that stands in parallel with the axis on the bumper2may be used to have the same effect.

Furthermore, the free end of the metal spring5may be formed to be positioned in the through hole4hwithout being pushed by the wall of the hole2a.

Furthermore, the bezel4and the sensor body3may be formed in a shape other than the cylindrical shape as described in the embodiments. That is, the bezel4may be in an oval shape, or in a polygonal tubular shape, and the body3may be in a corresponding shape of the hollow in the bezel4.

Furthermore, the ultrasonic sensor1may be disposed on a vehicle part that is different from a bumper by having the structure described in the present disclosure.

Furthermore, the metal spring5may be integrally formed with the bezel4instead of being attached on the bezel4after forming the bezel4.

Furthermore, the metal spring5may be replaced with other resilient body that is formed with a material different from the metal. The number of the metal spring5may be different from4. The number of the spring5is preferably at least two. The arrangement of the springs5may not be equidistant as long as force balance between the springs5is maintained.