Patent ID: 12253597

MODES FOR CARRYING OUT THE INVENTION

EMBODIMENTS

Embodiments in this disclosure will be described below with reference to the drawings. Possible modifications of each embodiment will be all discussed following explanation of the embodiments in order not to disturb understanding of each embodiment.

Vehicle Structure

Referring toFIG.1, the ultrasonic sensors1in this embodiment are configured as vehicle-mounted clearance sonars attached to the vehicle V. Each of the ultrasonic sensors1mounted in the vehicle V works to detect an object(s) around the vehicle V.

The vehicle V is a four-wheeled automotive vehicle and equipped with the box-shaped vehicle body V1the body panel V2that is a plate-like body member, i.e., an exterior body panel, the front bumper V3, and the rear bumper V4. The front bumper V3is attached to a front end of the vehicle body V1. The rear bumper V4is attached to a rear end of the vehicle body V1. The front bumper V3and the rear bumper V4are made of metallic plates.

Some of the ultrasonic sensors1are configured to be secured to the front bumper V3to detect an object existing in front of or on a front lateral side of the vehicle V. The other ultrasonic sensors1are also configured to be secured to the rear bumper V4to detect an object existing in the back of or a rear lateral side of the vehicle V. In the following discussion, the state where each of the ultrasonic sensors1is attached to the front bumper V3or the rear bumper V4secured to the vehicle body V1will be referred to as an on-vehicle state or a vehicle-mounted state.

Specifically, in the vehicle-mounted state, a plurality of (e.g., four) ultrasonic sensors1are mounted in the front bumper V3. The ultrasonic sensors1in the front bumper V3are located away from each other in the width-wise direction of the vehicle V. Similarly, a plurality of (e.g., four) ultrasonic sensors1are mounted in the rear bumper V4. Each of the front bumper V3and the rear bumper V4has formed therein the mounting holes V5in which the ultrasonic sensors1are installed. The mounting or demounting of the ultrasonic sensors1in or from the front bumper V3is usually achieved after the front bumper V3is removed from the vehicle body V1. The vehicle-mounted state, as referred to in this disclosure, also includes a state where the ultrasonic sensors1are merely installed in the front bumper V3without the front bumper V3being attached to the vehicle body Vl. The same applies to the mounting or demounting of the ultrasonic sensors1in or from the rear bumper V4.

First Embodiment

FIGS.2A to2Cillustrate the vehicle-mounted state of only one of the ultrasonic sensors1attached to the front bumper V3for the brevity of illustration. The following discussion will refer to the structure of the ultrasonic sensor1in the first embodiment with reference toFIG.2A. For the sake of convenience of explanation, a right-handed Cartesian coordinate (X, Y, Z) system is defined based on a direction of gravity's pull in the vehicle- mounted state. In the illustrated right-handed coordinate system, an upward direction (i.e., a vertical direction) will be referred to as a positive Z-axis direction. The vertical direction, as referred to herein, is a direction opposite to a direction of the force of gravity when the vehicle Vis placed in a drivable condition on a horizontal plane. The upward direction, as referred to herein, coincides with an upward vertical direction or a direction oriented at a small acute angle a (e.g., 10° or less) to the upward vertical direction. The positive Z-axis direction, therefore, becomes identical with the upward vertical direction or a direction traversing the upward vertical direction depending upon the configuration of the front bumper V. Similarly, the Y-axis direction becomes identical with the horizontal direction or a direction traversing the horizontal direction.

Referring toFIGS.2A to2C, the front bumper V3has an outer bumper surface V31and an inner bumper surface V32.

The outer bumper surface V31is an outside surface of the front bumper V3which faces or is exposed to the bumper-outside space SG existing outside the vehicle V in the vehicle-mounted state. The inner bumper surface V32is an inside surface of the outer bumper surface V31which faces or is exposed to the bumper- inside space SN existing inside the vehicle V in the vehicle- mounted state. Each of the mounting holes V5opens at the outer bumper surface V31and the inner bumper surface V32, in other words, extends through a thickness of the front bumper V3. Each of the mounting holes V5is in the form of a circular hole defining a circular cylindrical space in the front bumper V3. Each of the mounting holes V5, therefore, has a cylindrical inner surface V51.

Each of the ultrasonic sensors1is configured to generate or sense ultrasound energy. Specifically, each of the ultrasonic sensors1is designed to emit a detecting wave in the form of ultrasound into the bumper-outside space SG along the center axis line CL. Each of the ultrasonic sensors1also works to receive a wave including a return (which will also be referred to as a reflected wave) of the detecting wave from an object existing in the bumper-outside space SG and analyze the received wave to output a sensing signal created using results of the analysis of the received signal.

In the illustrated right-handed coordinate (X, Y, Z) system, a direction in which the detecting wave is outputted and which extends parallel to the center axis line CL that coincides with a directivity axis (i.e., an axis of maximum radiation intensity) of each of the ultrasonic sensors1will also be referred to as a positive Y-axis direction. The directivity axis, as referred to herein, is defined by an imaginary straight line extending in a direction in which ultrasound, as emitted from the ultrasonic sensor1, travels. The directivity axis serves as a base for defining a directivity angle. The directivity axis is also referred to as a center directivity axis or a sensing axis. A positive Y-axis direction oriented parallel to the directivity axis will also be referred to as an axial direction. In the following discussion, assuming that a member shaped to extend in the axial direction has ends opposed to each other in the axial direction, one of the ends of the member which faces in the positive Y-axis direction will also be referred to as a front end or a front end portion facing in the axial direction, while the other end of the member which faces in a negative Y-axis direction will also be referred to as a base end or a base end portion facing in the axial direction. A dimension of a member or a part of the member, as discussed below, which is measured in the axial direction will also be referred to as an axial direction dimension.

In the following discussion, a direction perpendicular to the axial direction will also be referred to as an in-plane direction which extends parallel to an X-Z plane. The shape of a member, as viewed on a plane extending orthogonal to the center axis line CL, in other words, as projected onto the X-Z plane, will also be referred to as an in-plane shape.

The in-plane direction includes a radial direction and a circumferential direction. The radial direction is defined as a direction extending radially from the center axis line CL. In other words, the radial direction is oriented at right angles to the center axis line CL and extends away from the center axis line CL. Specifically, given a point of intersection of the center axis line CL with an imaginary plane, as defined perpendicular to the center axis line CL, and an initial point that is such a point of intersection, the radial direction coincides with a direction along a half-line defined to extend from the initial point on the imaginary plane. In other words, given an imaginary circle defined on the imaginary plane, and the center of the imaginary circle lying at the point of intersection between the imaginary plane and the center axis line CL, the radial direction is a direction along the radius of the imaginary circle. The circumferential direction is defined along a circumference of the above imaginary circle extending around the center axis line CL.

Each of the ultrasonic sensors1is mounted in the vehicle V to have the center axis line CL extending substantially parallel to a thickness-wise direction of a portion of the front bumper V3which is near a mounting location where a corresponding one of the ultrasonic sensors1is attached to the front bumper V3. The mounting location, as referred to herein, is where each of the ultrasonic sensors1is attached to the front bumper V3, in other words, the center of each of the mounting holes V5. The center of each of the mounting holes V5, as referred to herein, is the center of a circle defined by a line of intersection between the edge of the cylindrical inner surface V51of the mounting hole V5and the outer bumper surface V31or the inner bumper surface V32. In other words, the center of each of the mounting holes V5may be presumed to the position of the center axis line CL on an X-Z coordinate plane in the vehicle-mounted state or the bumper- mounted state.

Referring toFIGS.2A to2C and3, each of the ultrasonic sensors1is equipped with the sensor body2. The sensor body2includes the sensor case3, the cushion4, and the ultrasonic microphone5. The sensor body2is attached to the front bumper V3using the anti-vibration spacer6, the bezel7, and the retainer8. The parts of each of the ultrasonic sensors1will be described below in detail.

Sensor Case

FIG.3illustrates the sensor body2after the retainer8is removed from the ultrasonic sensor1illustrated inFIGS.2A to2C, pulling a sub-assembly of the ultrasonic sensor1from which the retainer8is removed toward the bumper-outside space SG, and then dismounting the bezel7from the sub-assembly. The sub- assembly, as referred to herein, is an assembly of the sensor body2to which the anti-vibration spacer6and the bezel7are attached. Referring toFIG.3, the sensor case3serving as a housing of the ultrasonic sensor1, i.e., the sensor body2includes the box31, the connector32, and the microphone support33. The sensor case3is made in the form of a one-piece from a hard synthetic resin, such as polybutylene terephthalate, acrylonitrile- butadiene-styrene (ABS) resin, polypropylene, polycarbonate, or polystyrene.

The box31is of a flat-box shape and has a length extending in the X-axis direction and a thickness in the Y-axis direction in the bumper-mounted state. The box31has the circuit board34disposed therein. The circuit board34is electrically connected to the ultrasonic microphone5using the connecting wires35.

The boxy31has a length with a first end (i.e., a left end, as viewed inFIGS.2A and3) and a second end opposed to the first end. The connector32extends from the first end of the box31horizontally and obliquely backward in the vehicle-mounted state. In other words, the connector32extends away from the front bumper V3in the bumper-mounted state. The connector32is designed in the form of a receptable connector which is joinable to or detachable from a plug connector, not shown, attached to an end of a wire harness used for electrical connection with an external device, such as an electronic control unit (ECU).

The microphone support33extends in the axial direction from the second end (i.e., a right end, as viewed inFIGS.2A and3) of the box31. The microphone support33is of a hollow cylindrical shape surrounding the center axis line CL. In this embodiment, the microphone support33is shaped to have a center axis coinciding with the center axis line CL. The microphone support33has a front end which faces in the axial direction and on which the joint protrusion36is formed. The joint protrusion36is designed in the form of a protrusion extending toward the center axis line CL from a cylindrical inner wall of the microphone support33surrounding the center axis line CL. The joint protrusion36also extends on an entire circumference of the inner wall of the microphone support33.

Cushion

The cushion4is made in the form of a hollow cylinder from an elastic synthetic resin, such as silicon rubber, and surrounds the center axis line CL. Specifically, the cushion4in this embodiment is of a hollow cylindrical shape surrounding the center axis line CL and has an outer diameter substantially identical with that of the microphone support33.

The cushion4has the supported portion41that is a base end facing in the axial direction and is secured at the supported portion41to the microphone support33. Specifically, the supported portion41has formed therein the joint groove42opening in the radial direction. The joint groove42is shaped to achieve a mechanical joint to the joint protrusion36of the microphone support33. The joint groove42extends in the circumferential direction.

The microphone housing43which is located closer to the front end of the sensor body2than the supported portion41of the cushion4is in the axial direction is shaped to have the ultrasonic microphone5disposed substantially fully therein without protruding outside the microphone housing43in the axial direction. In other words, the microphone housing43has a cylindrical inner chamber contoured to conform with an outer shape of the ultrasonic microphone5.

The microphone housing43is equipped with a pair of joint protrusions44. The joint protrusions44are diametrically opposed to each other through the center axis line CL. The joint protrusions44are countered to achieve mechanical fits quadrangular grooves and extend toward the center axis line CL. Each of the joint protrusions44has a rectangular cross section also extends in the Z-axis direction as viewed in the drawings.

As apparent from the above discussion, the cushion4which has the base end and the front end opposed to the base end in the axial direction is secured at the base end to the sensor case3and elastically retains the ultrasonic microphone5in the front end. The ultrasonic microphone5is, therefore, held by the sensor case3through the cushion4.

The cushion4works to minimize transmission of mechanical vibration between the sensor case3and the ultrasonic microphone5. The cushion4is shaped to surround the ultrasonic microphone5and disposed inside the bezel7in an assembled state. The assembled state, as referred to herein, is a state where the anti-vibration spacer6and the bezel7are attached to the sensor body2. The above-described sub- assembly is in the assembled state. The bumper-mounted state and the vehicle-mounted state are also equivalent to the assembled state. The cushion4is located between the ultrasonic microphone5and the front bumper V3in the vehicle-mounted state to absorb mechanical vibration transmitting between the ultrasonic microphone5and the front bumper V3.

Ultrasonic Microphone

The ultrasonic microphone5is of a cylindrical outer shape extending in the axial direction. Specifically, the ultrasonic microphone5is in the shape of a circular cylinder whose center axis coincides with the center axis line CL.

The ultrasonic microphone5includes the ultrasonic device51and the microphone case52. The ultrasonic device51is implemented by an electrical energy-to-mechanical energy transducer made of a thin-film piezoelectric device. The ultrasonic device51is disposed inside the microphone case52.

The microphone case52serves as a housing for the ultrasonic microphone5and is made in the form of a bottomed hollow cylinder from a metallic material, such as aluminum. Specifically, the microphone case52includes the diaphragm53and the side plate54.

The diaphragm53is in the form of a thin plate having a thickness, as measured in the axial direction. The diaphragm53is arranged to close a front end of the side plate54which faces in the axial direction. In the bumper-mounted state or the vehicle- mounted state, the diaphragm53is oriented to have a smooth outer surface exposed to the bumper-outside space SG. The diaphragm53has an inner surface which is opposed to the outer surface thereof and on which the ultrasonic device51is fixed.

The side plate54of the microphone case52is of a substantially hollow cylindrical shape and extends in the axial direction. The side plate54has formed therein a pair of joint grooves55contoured to achieve fits with the joint protrusions44.

Anti-Vibration Spacer

Referring toFIGS.4A and4B, the anti-vibration spacer6is in the shape of a thin ring and has a thickness as measured in the axial direction. The anti-vibration spacer6is made from an elastic synthetic resin, such as silicon rubber. Specifically, the anti-vibration spacer6is in the form of a disc plate and has the spacer through-hole61formed in the center of the disc plate.

The anti-vibration spacer6is, as clearly illustrated inFIGS.2A and2C, arranged between the flange71, as will be described later in detail, of the bezel7and the front bumper V3to minimize the transmission of mechanical vibration between the bezel7and the front bumper V3in the vehicle-mounted state. Specifically, the anti-vibration spacer6is firmly retained by the reverse surface71a of the flange71which faces the front bumper V3and the outer bumper surface V31in the bumper-mounted state.

BEZEL

FIG.5illustrates the above-described sub-assembly. FIGS.

6A to6C schematically illustrate the structure of the bezel7. The structure of the bezel7will be described below with reference toFIGS.2A to6C.

The bezel7serving as a sensor attachment in this disclosure is used to attach the ultrasonic sensors1to the front bumper V3that is a plate-like vehicle body member. The bezel7is made in the form of a one-piece member from synthetic resin and includes the flange71and the hollow cylinder72.

The flange71is in a ring shape and has a thickness as measured in the axial direction. The flange71is located on a front end of the cylinder72which faces in the axial direction and extend in the radial direction. The flange71is shaped to have an outer dimeter larger than an inner diameter of the mounting hole V5. In the bumper-mounted state, the flange71, as clearly illustrated inFIGS.2A and2C, faces a portion of the outer bumper surface V31around the mounting hole V5through the anti- vibration spacer6.

In the assembled state or the bumper-mounted state, the cylinder72is disposed inside the mounting hole V5and surrounds the cushion4and the ultrasonic microphone5. In other words, the cylinder72is shaped to have an outer diameter slightly smaller than the inner diameter of the mounting hole V5and also has an inner diameter slightly larger than outer diameters of the microphone support33and the cushion4. The cylinder72has joint portions, not shown, which achieves detachable engagement with the microphone support33in the assembled state.

The cylinder72has the spacer housing groove73which is formed in a front end portion thereof facing in the axial direction and in which the anti-vibration spacer6is disposed. The spacer housing groove73has an opening facing in the radial direction. The spacer housing groove73occupies an entire circumference of the cylinder72. The spacer housing groove73has a width (i.e., a dimension as measured in the axial direction) substantially identical with the thickness of the anti-vibration spacer6and also has a depth (i.e., a dimension as measured in the radial direction) which defines an inner diameter of the spacer housing groove73substantially identical with the diameter of the spacer through- hole61of the anti-vibration spacer6.

Referring toFIG.6C, the cylinder72has the main body74which is of a hollow cylindrical shape and occupies a middle portion of the cylinder72which extends in the axial direction. The main body74extends in the center axis line CL. The main body74has a base end facing in the axial direction and also has a pair of base end protrusions75formed integrally with the base end of the main body74. The base end protrusions75project in the radial direction. The main body74and the base end protrusions75are made from the same materials in the form of a seamless one-piece member.

Each of the base end protrusions75is formed by a portion of the cylinder72which is located closest to the base end of the cylinder72in the axial direction. The base end protrusions75extend in the radial direction, i.e., a direction parallel to the Z- axis direction inFIG.6C. Each of the base end protrusions75has the retainer contact face75a which defines a front end surface thereof facing in the axial direction and is in the form of a flat and smooth face shaped to have a normal line oriented parallel to the center axis line CL.

The bezel7has a pair of retainer fit grooves76formed in portions thereof which are located closer to the front end of the bezel7than the retainer contact face75a are in the axial direction.

The retainer fit grooves76have openings which face outward, in other words, away from the center axis line CL. The retainer fit grooves76are diametrically or symmetrically opposed to each other across the center axis line CL. The retainer fit grooves76define spaces into which the retainer8is inserted or fit when the ultrasonic sensors1is attached to the front bumper V3. Each of the retainer fit grooves76extends in the X-axis direction in the form of a square groove. The base end protrusions75serve to hold the retainer8, as inserted into the retainer fit grooves76, between itself and the inner bumper surface V32in the bumper- mounted state.

The retainer fit grooves76are defined by the base end protrusions75and the front end protrusions77. The front end protrusions77are formed by portions of the cylinder72which are closest to the front end of the cylinder72in the axial direction. The front end protrusions77are located adjacent to the spacer housing groove73in the axial direction. In other words, the spacer housing groove73is shaped to include air gaps between the flange71and the front end protrusions77.

The main body74has the two front end protrusions77located on the front end thereof facing in the axial direction. The front end protrusions77are joined integrally with the main body74and protrude in the radial direction. The main body74and the front end protrusions77are made from the same materials in the form of a seamless one-piece member. Each of the front end protrusions77extends in the circumferential direction. Specifically, the front end protrusions77, as can be seen in FIGS.

6A and6C, occupy a portion of the circumference of the bezel7, in other words, they are located away from each other through air gaps therebetween in the circumferential direction of the bezel7.

FIG.7is an enlarged view which illustrates major parts of the bezel7in this embodiment and peripheries thereof. Each of the front end protrusions77, as illustrated inFIG.7, includes the base portion77a, the middle portion77b, and the end portion77c. The base portion77a, the middle portion77b, and the end portion77c are arranged adjacent to each other in this order in the radial direction.

The base portion77a is located closest to the main body74in the front end protrusion77and shaped to have a dimension, as measured in the axial direction, which is larger than the thickness of the front bumper V3. The middle portion77b is arranged between the base portion77a and the end portion77c in alignment therewith in the radial direction. The middle portion77b has a dimension substantially identical with that of the base portion77a in the axial direction. The end portion77c is located farthest from the main body74in the front end protrusion77and tapered to have a dimension, as measured in the axial direction, which decreases gradually outward in the radial direction.

Through-Hole Facing Portion

The bezel7has the through-hole facing portion78defined by a portion of the cylinder72. The through-hole facing portion78faces the inner surface V51of the mounting hole V5in the radial direction in close proximity to the inner surface V51to be contactable with the inner surface V51in the bumper-mounted state. Specifically, the through-hole facing portion78in this embodiment is defined by the end portion77c of the front end protrusion77which faces in the radial direction. More specifically, the through-hole facing portion78is defined by a surface of the end portion77c which faces the inner surface V51in the vicinity of the inner surface V51.

The through-hole facing portion78is designed to have a contact surface-decreasing structure which creates a decreased area contacting with the inner surface V51. Specifically, the contact surface-decreasing structure of the end portion77c has a plurality of protrusions78a formed on a surface of the end portion77c which faces the inner surface V51in close proximity to the inner surface V51. The protrusions78a project in the radial direction. Each of the protrusions78a is in a semi-circular shape or a circular conical shape with a round apex.

Retainer

The retainer8is, as clearly illustrated inFIGS.2A to2C, attached to the sub-assembly fit in the mounting hole V5to firmly attach the ultrasonic sensors1to the front bumper V3. The retainer8is formed by a one-piece member made from a hard synthetic resin.

FIGS.8A to8Dschematically illustrate the structure of the retainer8. The retainer8, as shown inFIG.8A, has the retainer body81constituting a major body of the retainer8. The retainer8is of a substantially U-shape, as viewed facing the front thereof and has the opening82facing the negative X-axis direction. Specifically, the retainer body81, as can be seen inFIGS.8A to8D, includes the connecting portion82and a pair of extensions84. The connecting portion83extends in the Z-axis direction, as viewed in the drawings. The extensions84extend from opposed ends of the connecting portion83in the negative X-axis direction, as viewed in the drawings. The extensions84defines the opening82therebetween. The opening82defines a space in which the bezel7is disposed and held by the extensions84. The extensions84are, as clearly illustrated inFIGS.2A to8D, mechanically strengthened by the plate-shaped reinforcements85. Each of the reinforcements85has a thickness, as measured in a direction perpendicular to the Z-axis direction, and is bent in a reverse U-shape with an opening facing in the negative Y-axis direction. The reinforcements85are located outside the extensions84, in other words, arranged to face away from the opening82.

The extensions84are equipped with the guides86. Each of the guides86is, as illustrated inFIGS.8A to8D, in a plate- shape having a thickness, as measured in a direction perpendicular to the Z-axis direction. Specifically, each of the guides86has the bend86a. Each of the guides86extends from the connecting portion83to the bend86a in the negative X-axis direction and also extends from the bend86a obliquely, in other words, both in the negative X-axis direction and the positive Y- axis direction, as viewed in the drawings.

Each of the guides86has the bezel contact face87which is defined by an outer surface thereof exposed in the negative Y- axis direction. Each of the bezel contact faces87is placed in abutment with the retainer contact face75a of the bezel7in the bumper-mounted state. Each of the bezel contact faces87includes the plane surface87a and the slant surface87b. The plane surface87a is located closer to the connecting portion83than the bend86a of the bezel contact face87is. The plane surface87a is smooth or flat and shaped to have a normal line extending parallel to the center axis line CL in the bumper- mounted state. The plane surface87a is placed in abutment with the retainer contact face75a in the bumper-mounted state. The slant surface87b is located closer to the opening82than the bend86a of the bezel contact face87is. The slant surface87b is shaped to have a normal line crossing the center axis line CL at a given small angle (e.g.,15° to)30° in the bumper-mounted state.

The retainer8has the elastic portions88each of which works as a leaf spring and extends from the retainer body81in the form of a cantilever. The elastic portions88, as can be seen inFIG.8D, extend from a middle portion of a length of each of the extensions84to be oblique to the positive Y-axis direction. Specifically, each of the extensions84has the two elastic portions88arranged in a gull-wing shape. The elastic portions88are placed in abutment with the inner bumper surface V32to be elastically deformable in the bumper-mounted state where the retainer8is held between the retainer contact face75a and the inner bumper surface V32.

Beneficial Advantages

How to attach the ultrasonic sensors1to the front bumper V3and the bumper-mounted state will be described below along with beneficial advantages offered by the structure in this embodiment with reference to the drawings. For the sake of simplicity, the following attachment method or attachment steps for the ultrasonic sensors1will be discussed using a right-handed Cartesian coordinate (X, Y, Z) system defined based on the illustrated vehicle-mounted state. The mounting or demounting of the ultrasonic sensors1in or from the front bumper V3or the rear bumper V4is, as described above, usually achieved after the front bumper V3or the rear bumper V4is removed from the vehicle body V1, so that the positive Z-axis direction may be different from the upward direction when the ultrasonic sensors1are actually attached to or removed from the front bumper V3or the rear bumper V4.

First, the sensor body2illustrated inFIG.3is produced. The anti-vibration spacer6illustrated inFIG.4Ais attached to the bezel7illustrated inFIG.6A. Subsequently, the cushion4and the ultrasonic microphone5of the sensor body2are inserted into the bezel7on which the anti-vibration spacer6is fit. This causes joints, not shown, of the cylinder72to engage the microphone support33, thereby securing the bezel7to the sensor body2. The bezel7with the anti-vibration spacer6is attached to the sensor body2in the above manner, thereby fabricating the sub-assembly illustrated inFIG.5. In the sub-assembly, the cushion4surrounds the ultrasonic microphone5in the cylinder72of the bezel7.

The sub-assembly illustrated inFIG.5is inserted at the connector32into each of the mounting holes V5from the bumper- outside space SG. Subsequently, the sub-assembly is placed in a temporary assembly state where the anti-vibration spacer6faces in direct abutment with or in close proximity to the outer bumper surface V31of the front bumper V3with the connector32extending in the negative X-axis direction, as viewed facing the reverse surface of the sub-assembly inFIG.2B. Simultaneously, the retainer8is placed in a mountable/demountable state in the bumper-inside space SN. The mountable/demountable state is a state of the retainer8where the opening82faces in the negative X-axis direction, and the elastic portions88face the inner bumper surface V32.

The bezel7of the sub-assembly in the temporary assembly state is inserted into the opening of the retainer8placed in the mountable/demountable state. Subsequently, the extensions84of the retainer8are thrust in the negative X-axis direction and then inserted into the retainer fit grooves76of the bezel7of the sub-assembly. In such insertion of the extensions84, portions of the guides86around the opening82are fitted into the retainer fit grooves76completely or almost without the elastic portions88of the retainer8being elastically deformed in the negative Y-axis direction. Afterwards, the slant surface78b of the bezel contact face87of each of the guides86is then placed in abutment with the retainer contact face75a. An additional thrust of the retainer8in the negative X-axis direction results in a gradual increase in elastic deformation of the elastic portions88in the negative Y- axis direction.

When the retainer8is thrust in the negative X-axis direction until the bezel7and the connecting portion83of the retainer8contact with each other, it causes the plane surface87a of the bezel contact face87of each of the guides86to contact with the retainer contact face75a. This causes the retainer8to be held by spring pressure produced by the elastic portions88firmly between the base end protrusions75of the bezel7and the inner bumper surface V32. In this way, the retainer8is fitted in the sub-assembly in the temporary assembly state, thereby achieving the bumper-mounted state where the ultrasonic sensor1is, as illustrated inFIGS.2A to2C, mounted in the front bumper V3or the vehicle-mounted state.

In the bumper-mounted state or the vehicle-mounted state, the cushion4, the anti-vibration spacer6, and the bezel7, as clearly illustrated inFIG.7, lie between the ultrasonic microphone5and the front bumper V3. Specifically, the cushion7is held between the ultrasonic microphone5and the bezel7. The anti- vibration spacer6is held between the flange71of the bezel7and the front bumper V3.

Mechanical vibration between the ultrasonic microphone5and the front bumper V3which are opposed to each other through the bezel7are thought of as being transmitted through two transmission paths: a first one being a path extending between the flange71and the front bumper V3, and the second being a path extending between the front end protrusions77of the cylinder72and the front bumper V3. Th first transmission path has disposed thereon the anti-vibration spacer6made from a synthetic resin elastic material, thereby minimizing the transmission of vibration to the ultrasonic microphone5.

The second transmission path is, as described above, a path extending between the front end protrusions77of the cylinder72which face in the axial direction and the front bumper V3and does not have a vibration absorber, such as the anti- vibration spacer6. An increase in area of contact between each of the front end protrusions77and the inner surface V51of the mounting hole V5will accelerate the transmission of vibration to the ultrasonic microphone5. Particularly, in a case where the front bumper V3is made of a metallic plate in which the transmissibility of vibration is high, there is a risk that an error in detection by the ultrasonic microphone5may arise from the vibration.

The through-hole facing portion78of each of the front end protrusions77which faces the inner surface V51of the mounting hole V5is, as described above, designed to have the contact surface-decreasing structure which creates a decreased area contacting the inner surface V51. Specifically, the through-hole facing portion78of each of the front end portions77which occupies the surface of the end portion77c and faces the inner surface V51in close proximity to the inner surface V51, as described above, has the protrusions78a projecting in the radial direction. The protrusions78a decreases the area of contact between each of the front end protrusions77and the inner surface V51of the mounting hole V5, thereby reducing the transmission of vibration through the second transmission path.

The structure in this embodiment is capable of reducing or minimizing the transmission of mechanical vibration between each of the ultrasonic sensors1and an attachment object, i.e., the front bumper V3, thereby minimizing a risk of errors in object detection by the ultrasonic sensors1which may arise from the vibration between the ultrasonic sensors1and the front bumper V3.

Second Embodiment

The second embodiment will be described below with reference toFIGS.9and10. The following discussion will refer only to parts different from those in the first embodiment. The same parts as those in the first embodiment or equivalents thereof will be referred to using the same reference numbers or symbols as those in the first embodiment. In the following discussion, the same explanation as in the first embodiment, therefore, holds true for the parts in the second embodiment indicated by the same reference numbers or symbols as those in the first embodiment unless otherwise specified. The same is true for the third embodiment which will be described later.

The front end protrusions77in the above-described first embodiment do not occupy the entire circumference of the bezel7. In other words, the circumference of the bezel7partially has an omission(s) of the front end protrusions77. Each of the front end protrusions77in the first embodiment is designed to have protrusions78a arranged over the circumference thereof.

In contrast to the above structure, the bezel7in the second embodiment, as illustrated inFIG.9, has the front end protrusion77shaped to occupy the entire circumference of the bezel7. The front end protrusion77has the contact surface-decreasing structure which includes the protrusions78a which may be designed, as illustrated inFIG.10, to have the protrusions78a arranged over the entire circumference of the front end protrusion77(i.e., the bezel7). This reduces the transmission of mechanical vibration between the ultrasonic sensor1and the front bumper V3.

Third Embodiment The third embodiment will be described below with reference to FIG.11. The third embodiment is a modification of the second embodiment.

The protrusions78a having the contact surface-decreasing structure in this embodiment are designed in the form of an embossed pattern, in other words, shaped by raised and recessed portions of the front end protrusion77which are finer in size than in the second embodiment. Such configuration of the protrusions78a offers substantially the same beneficial advantages as in the second embodiment.

Fourth Embodiment

The fourth embodiment will be described below with reference toFIGS.12and13. The fourth embodiment is a modification of the third embodiment.

The directivity of each ultrasonic sensor1is sometimes required to be regulated to reduce reception of unwanted reflections from a road surface. Typically, such requirements are made to decrease the directivity angle in the vertical direction to be smaller than that in the horizontal direction. In order to achieve such regulation of the directivity, the diaphragm53is, as illustrated inFIG.12, designed to have the in-plane shape with a long dimension and a short dimension perpendicular to the long dimension. Specifically, the diaphragm53is of an ellipse or oval shape to have the long dimension oriented in the vertical direction in the vehicle-mounted state.

The side plate54of the microphone case52includes the thin-walled portions541and the thick-walled portions542. The thin-walled portions541lie at opposed ends of the length of the diaphragm53. The thick-walled portions542are opposed to each other in the width-wise direction of the diaphragm53. The diaphragm53is oriented to have the length extending in the vertical direction. The width (i.e., the short dimension) of the diaphragm53which is perpendicular to the length thereof extend in the horizontal direction.

The thin-walled portions541usually vibrate at a higher frequency than the thick-walled portions542. This leads to a concern about transmission of vibration between the front bumper V3and an upper or a lower end portion of the microphone case52aligning the thin-walled portions541in the vehicle-mounted state.

In order to alleviate the above problem, the protrusions78a serving as the contact surface-decreasing structure are, as can be seen inFIG.13, arranged at least in alignment with the end portions of the diaphragm53which are opposed to each other in the length-wise direction of the diaphragm53. Specifically, the front end protrusion77is designed to have the protrusions78a arranged at two discrete locations on the circumference thereof in alignment with the thin-walled portions541. With these arrangements, portions of the front end protrusion77where there are no protrusions78a works to minimize undesirable play of the bezel7in the vehicle-mounted state, while the protrusions78a function to reduce the transmission of vibration through the above-described second transmission path in the vehicle-mounted state.

Fifth Embodiment

The fifth embodiment will be described below with reference toFIG.14. The fifth embodiment is a modification of the first to fourth embodiments. Specifically, the fifth embodiment is designed to have a contact-surface-deceasing structure different from those in the first to fourth embodiments.

The contact surface-decreasing structure in this embodiment is, as clearly illustrated inFIG.14, configured in the form of a tapered structure. Specifically, the front end protrusion(s)77tapers in the radial direction so that the thickness (i.e., dimension in the axial direction) of the end portion77c is smaller than the thickness of the front bumper V3. More specifically, the front end protrusion(s)77is shaped to have the dimension, as measured in the axial direction, which decreases linearly from the base portion77a to the end portion77c.

The front end protrusion(s)77is also shaped to have the dimension, as measured in the axial direction, which is smaller than the thickness of the front bumper V3between the base portion77a and the end portion77c. In other words, the tapered structure of the front end protrusion(s)77is shaped to be disposed fully inside the mounting hole V5in the bumper- mounted state.

The front end protrusion(s)77, therefore, has a decreased area of contact with the inner surface V51of the mounting hole

V5, thereby reducing the transmission of vibration through the second transmission path. The structure of the ultrasonic sensors1in this embodiment is, therefore, capable of minimizing the transmission of mechanical vibration from the front bumper

V3to the ultrasonic sensors1and a risk of errors in object detection by the ultrasonic sensors1which may arise from the vibration.

The front end protrusion(s)77may be designed to have the above-described tapered surface which occupies a portion(s) or the whole of circumference thereof. The tapered surface may alternatively be aligned with the end portions of the diaphragm53which are opposed to each other in the lengthwise direction thereof.

Sixth Embodiment

The sixth embodiment will be described below with reference toFIG.15. The fourth embodiment is a modification of the fifth embodiment.

The end portion77c of the front end protrusion(s)77in this embodiment is, as can be seen inFIG.15, round in a convex shape facing in the radial direction. Specifically, the tapered structure of the front end protrusion(s)77, as shown inFIG.15, includes the convex curved end surface781.

The above configuration of the front end protrusion(s)77decreases an area of contact with the inner surface V51of the mounting hole V5, which minimizes the transmission of vibration through the second transmission path. The structure of the ultrasonic sensors1in this embodiment is, therefore, capable of minimizing the transmission of mechanical vibration from the front bumper V3to the ultrasonic sensors1and a risk of errors in object detection by the ultrasonic sensors1which may arise from the vibration.

Seventh Embodiment

The seventh embodiment will be described below with reference toFIGS.16and17. The seventh embodiment is a modification of the first to sixth embodiments.

In the adjustment of the directivity of the ultrasonic sensors1, an angular position of the ultrasonic sensor1around the center axis line CL in the circumferential direction may be set to a given position in the bumper-mounted state or the vehicle- mounted state. The ultrasonic sensors1may also be regulated in position thereof to orient the connector32in a selected direction in order to achieve wiring to the ultrasonic sensor1.

In order to facilitate the above operation, the front end protrusion(s)77of the bezel7in this embodiment is, as illustrated inFIG.16, designed to have the bezel joint782which will also be referred to as an attachment joint. The bezel joint782is configured to achieve firm engagement with the bumper joint V52illustrated inFIG.17which will also be referred to as a vehicle body part joint. The bumper joint V52includes a portion of the front bumper V3which occupies a portion of the circumference of the mounting hole V5and is shaped to create a change in inner diameter of the mounting hole V5which is substantially circular and extends through the thickness of the front bumper V3. The inner diameter of the mounting hole V5, as referred to herein, is a distance between the center CP of the mounting hole V5and the inner surface V51.

Specifically, the bezel joint782in this embodiment includes the bezel recess783and a pair of bezel protrusions784. The bezel recess783is defined by a recessed portion of the front end protrusion77which has an opening facing in the radial direction and is located in a portion of the circumference of the front end protrusion77. The bezel protrusions784are created by portions of the front end protrusion77which are located on opposite sides of the bezel recess783in the circumferential direction and viewed as being relatively raised by forming the bezel recess783in the front end protrusion77.

The bumper joint V52is contoured to achieve fit in the bezel joint782. Specifically, the bumper joint V52includes the bumper protrusion V53and a pair of bumper recesses54. The bumper protrusion53is defined by a portion of the inner surface V51of the mounting hole V5which is raised to face toward the center CP of the mounting hole V5. The bumper protrusion53is contoured to achieve fit in the bezel recess783. The bumper recesses V54are defined by portions of the inner surface V51of the mounting hole V5which are located on opposite sides of the bumper protrusion V53in the circumferential direction and viewed as being relatively recessed by raising a portion of the inner surface V51to create the bumper protrusion V53. The bumper recesses V54are contoured to achieve the fit with the bezel protrusions784.

The ultrasonic sensor1is kept in a selected angular position around the center axis line CL in the bumper-mounted state by achieving firm engagement between the bezel joint782and the bumper joint V52. The selected angular position of the ultrasonic sensor1, as referred to herein, is set to lie in a range of a reference position ±0around the center axis line CL where0is an allowable angle, e.g.,0.5° to1° . The reference position is a position of the ultrasonic sensor1where the circumferential center of the bezel joint782coincides with that of the bumper joint V52in the radial direction.

When the ultrasonic sensor1is in the reference position, an area of contact between the bezel joint782and the bumper joint V52is minimized. However, when the sub-assembly is rotated by the allowable angle0from the reference position around the center axis line CL while keeping the engagement between the bezel joint782and the bumper joint V52, it will cause an area of contact between the bezel joint782and the bumper joint V52to be maximized because one of circumferentially opposed ends of the bumper protrusion V53contacts one of circumferentially opposed ends of the bezel recess783, and one of circumferentially opposed ends of the bumper recess V54contacts one of circumferentially opposed ends of the bezel protrusions784. This leads to an increased risk of the transmission of vibration from the front bumper V3to the ultrasonic sensor1as compared with when the ultrasonic sensor1is in the reference position.

In order to alleviate the above drawback, the contact surface-decreasing structure of the front end protrusion(s)77is designed to have the protrusions78a arranged at least on the bezel joint782. This structure of the ultrasonic sensor1is, therefore, capable of restricting the angular position of the ultrasonic sensor1within a desired range and minimizing the transmission of mechanical vibration from the front bumper V3to the ultrasonic sensors1and a risk of errors in object detection by the ultrasonic sensors1which may arise from the vibration.

The front end protrusion(s)77may have the contact surface-decreasing structure disposed on a portion(s) thereof other than the bezel joint782. For instance, the front end protrusion(s)77may have the contact surface-decreasing structure over the entire circumference thereof.

Modifications

This disclosure is not limited to the above embodiments. The above embodiment may, therefore, be modified in various ways. The following discussion will refer major modifications. The same parts as those in the above embodiments or equivalents thereof will be referred to using the same reference numbers or symbols as those in the above embodiments. In the following discussion, the same explanation as in the above embodiments, therefore, holds true for the parts in the following modifications indicated by the same reference numbers or symbols as those in the above embodiments unless otherwise specified.

For the sake of simplicity of disclosure, the above discussion has referred only to the ultrasonic sensors1mounted in the front bumper V3, but however, this disclosure is not limited to such a mode. The above embodiments may be used with the ultrasonic sensors1mounted in the rear bumper V4.

The ultrasonic sensors1may be attached to an object other than the front bumper V3or the rear bumper V4. For instance, the ultrasonic sensors1may be mounted in the body panel V2. In this case, the mounting holes V5are formed in the body panel V2.

The ultrasonic sensors1are not limited to sensors which emit or receive ultrasound. For instance, the ultrasonic sensors1may be designed only to emit ultrasound or alternatively only to receive returns of ultrasound, as emitted from another ultrasonic sensor, from an object(s) existing around the other ultrasonic sensor.

The parts of the ultrasonic sensors1may have structures different from those in the above embodiments or be made from materials different from those in the above embodiments. Two or more parts of the ultrasonic sensors1which are made from the same material in the above embodiments may also be made from materials different in kind from each other. Alternatively, two or more parts of the ultrasonic sensors1which are made from materials different from each other in the above embodiments may be made from the same material.

Two or more parts of the ultrasonic sensors1which are made of a seamless one-piece member in the above embodiments may be made of two or more discrete members adhered to joined to each other. Alternatively, two or more parts of the ultrasonic sensors1which are made of discrete members adhered or joined together in the above embodiments may be made of a seamless one-piece member.

The sensor case3or the cushion4may also be designed to have a structure different from that in the above embodiments. For instance, the mechanical structure or orientation of the connector32may be modified. The microphone support33or the cushion4may alternatively be made in the form of an oval cylindrical, elongated cylindrical, or polygonal cylindrical shape.

For instance, the ultrasonic microphone5may be retained by the microphone support33of the sensor case3without use of the cushion4. In this case, the cushion4may be shaped to be cylindrical and have a dimension substantially identical with that of the ultrasonic microphone5, i.e., the microphone case52in the axial direction.

The outer shape of the ultrasonic microphone5or the microphone case52needs not to be cylindrical, but may be oval cylindrical or polygonal cylindrical. The ultrasonic device51may alternatively be made of an electrical energy-to-mechanical energy transducer other than a piezoelectric device.

The bezel7or the retainer8which is an attachment member for use in attaching each of the ultrasonic sensors1to a plate-like member (e.g., the front bumper V3) of the vehicle body may also be designed to have a structure different from those in the above embodiments. For instance, the bezel7and/or the retainer8may be made of several parts different from those in the above embodiments.

The bezel7may alternatively be designed to have a retainer or a fastener to achieve fitting or attachment of itself to the part of the vehicle body instead of the retainer8.

The front end protrusion(s)77illustrated inFIG.14may be designed to have a plurality of protrusions78a arranged on the tip of the tapered end portion77c. In other words, the convex curved end surface781illustrated inFIG.15may include the protrusions78a arranged adjacent each other in the circumferential direction.

The concave-convex structures of the bezel joint782and the bumper joint V52illustrated inFIGS.16and17may be inverse of each other. Specifically, the bezel joint782may have protrusions extending in the radial direction outside the remaining portion of the front end protrusion77, while the bumper joint V52may have recesses whose depths are defined by increased inner diameters of corresponding portions of the mounting hole V5.

The component parts described in the above embodiments are not necessarily essential unless otherwise specified or viewed to be essential in principle. When the number of the component parts, a numerical number, a volume, or a range is referred to in the above discussion, this disclosure is not limited to it unless otherwise specified or viewed to be essential in principle. Similarly, when the shape of, the orientation of, or the positional relation among the component parts is referred to in the above discussion, this disclosure is not limited to it unless otherwise specified or viewed to be essential in principle.

The modifications are also not limited to the above- described examples. A portion or whole of the embodiment may be combined with one or some of the modifications.