WO2019139083A1

WO2019139083A1 - Liquid level detecting device

Info

Publication number: WO2019139083A1
Application number: PCT/JP2019/000542
Authority: WO
Inventors: 宮川　功
Original assignee: 株式会社デンソー
Priority date: 2018-01-15
Filing date: 2019-01-10
Publication date: 2019-07-18
Also published as: JP2020027097A

Abstract

A liquid level detecting device (100) is provided with an ultrasonic oscillating element (11) and a housing (2). The ultrasonic oscillating element is capable of transmitting and receiving ultrasonic waves. The housing has in the interior thereof a propagation pathway along which the ultrasonic waves propagate. The propagation pathway includes a first pathway (4) and a second pathway (5). The first pathway extends horizontally from a position at which the ultrasonic oscillating element is provided. The second pathway extends upward from the end of the first pathway on the opposite side to the position at which the ultrasonic oscillating element is provided. The first pathway includes a contracting portion (41) and a stepped portion (43). The cross-sectional area of the contracting portion contracts gradually with increasing distance from the ultrasonic oscillating element. The cross-sectional area of the stepped portion contracts in a stepwise manner at the end of the contracting portion. The housing includes a pathway air vent hole (6) providing communication between the inside and the outside of the housing, in a portion vertically above the step portion or vertically above a region in the vicinity of the step portion.

Description

Liquid level detection device

Cross-reference to related applications

This international application corresponds to Japanese Patent Application No. 2018-4294 filed with the Japanese Patent Office on January 15, 2018, and Japanese Patent Application No. filed from the Japanese Patent Office on August 13, 2018. It claims the priority based on 2018-152406, and the entire contents of Japanese Patent Application No. 2018-4294 and Japanese Patent Application No. 2018-152406 are incorporated by reference into this international application.

The present disclosure relates to a liquid level detection device.

There is known a liquid level detection device that detects the position of a liquid surface by transmitting ultrasonic waves by an ultrasonic oscillation element at the bottom of a tank storing liquid and receiving a reflected wave reflected by the liquid surface. . Generally, this type of liquid level detection device includes a housing having an internal space that functions as a propagation path of ultrasonic waves.

By the way, when air is accumulated in the internal space of the housing, the ultrasonic wave transmitted from the ultrasonic wave oscillation element may hit air and be reflected, and may be erroneously detected as a reflected wave reflected by the liquid surface. Patent Document 1 discloses a liquid level detection device in which an air vent is provided at the top of a propagation path.

JP 2004-340911 A Unexamined-Japanese-Patent No. 2006-145403

However, as a result of the inventor's detailed study, the location where air tends to stay in the internal space of the housing is not limited to the highest place in the vertical direction in the internal space, and the problem of being different according to the shape of the internal space It was issued.

For example, in the liquid level detection device described in Patent Document 2, the horizontal path for propagating the ultrasonic wave emitted from the ultrasonic oscillation element is tapered, and a stepped portion is formed on the tip side. Although there is a location higher in the vertical direction than the step in the horizontal path, the air accumulated in the step has a large contact area with the step, so that a problem arises that it is difficult to leave the step. In particular, since the reflected wave reflected by the step portion is used as a reference wave for calculating the position of the liquid level, the retention of air in the step portion can greatly affect the detection accuracy.

One aspect of the present disclosure is to provide a liquid level detection device capable of making it difficult for air to stay in a place where air tends to stay.

One aspect of the present disclosure is a liquid level detection device that detects the position of a liquid level, and includes an ultrasonic oscillation element and a housing. The ultrasonic oscillation element can transmit and receive ultrasonic waves. The housing internally has a propagation path through which ultrasonic waves propagate. The propagation path has a first path and a second path. The first path extends horizontally from the position where the ultrasonic oscillation element is provided. The second path extends upward from the end of the first path opposite to the position at which the ultrasonic oscillation element is provided. The first path has a reduction portion and a step portion. In the reduction section, the cross-sectional area gradually reduces as the distance from the ultrasonic oscillation element is increased. The stepped portion reduces the cross-sectional area in a step-like manner at the end of the reduction portion. The housing has a passage air vent hole communicating with the inside and outside of the housing at the vertical portion in the vicinity of the step portion or in the vertical direction.

According to such a configuration, the passage air vent hole is provided in the vicinity of the step portion or the step portion where air tends to stagnate, so that the air, which would otherwise be retained in the step portion, is outside the housing from the passage air vent hole. It is easy to go through. For this reason, it is possible to make the air difficult to stay in the step portion.

Another aspect of the present disclosure is a liquid level detection device that detects the position of a liquid level, and includes an ultrasonic oscillation element, a housing, and a case. The ultrasonic oscillation element can transmit and receive ultrasonic waves. The housing internally has a propagation path through which ultrasonic waves propagate. The case accommodates the ultrasonic oscillation element. The propagation path has a first path and a second path. The first path extends horizontally from the position where the ultrasonic oscillation element is provided. The second path extends upward from the end of the first path opposite to the position at which the ultrasonic oscillation element is provided. The case is disposed inside the housing with a gap between the case and the inner surface of the housing. The housing has a housing air vent hole communicating the inside and the outside of the housing at or near a portion located vertically above the gap.

According to such a configuration, the housing air venting hole is provided at or near the portion located vertically above the gap, which is a place where air tends to stagnate, so that the air that would otherwise be retained in the gap is the housing It is easy to escape from the air vent hole to the outside of the housing. For this reason, it is possible to make the air difficult to stay in the gap.

It is a sectional side view of the liquid level detection device of a 1st embodiment. It is a top view of the liquid level detection device of a 1st embodiment. It is an expanded side sectional view of the passage air vent hole located near the step of a 1st embodiment. It is an expanded side sectional view of the passage air vent hole located in the step of a 1st embodiment. It is an expanded side sectional view of a housing air vent hole of a 1st embodiment. It is a sectional side view of the liquid level detection device of a 2nd embodiment. It is a top view of the liquid level detection device of a 2nd embodiment. It is an enlarged plan view of a passage air vent hole and a passage hole cover of a liquid level detection device of a 2nd embodiment. It is an expanded sectional view of a passage air vent hole and a passage hole cover of a fluid level detection device of a 2nd embodiment. It is IX-IX sectional drawing of FIG. 8B. It is an enlarged plan view of a housing air vent hole and a housing hole cover of a liquid level detection device of a 2nd embodiment. It is an expanded sectional view of a housing air vent hole and a housing hole cover of a fluid level detection apparatus of a 2nd embodiment. It is a top view of a liquid level detection apparatus which has a slit hole. It is an enlarged plan view of a passage hole cover having plate portions arranged in a comb-like shape. It is an enlarged side view of a course hole cover which has a board part arranged in a comb-tooth shape. FIG. 7 is an enlarged plan view of a channel hole cover having a mesh ceiling. FIG. 5 is an enlarged side view of a channel hole cover having a mesh ceiling. It is an enlarged plan view of a U-shaped passage hole cover. It is an enlarged side view of a U-shaped passage hole cover. It is an enlarged plan view of a triangular path hole cover. FIG. 5 is an enlarged side view of a triangular shaped passage hole cover.

Hereinafter, exemplary embodiments of the present disclosure will be described with reference to the drawings.

[1. First embodiment]
[1-1. Constitution]
The liquid level detection device 100 shown in FIG. 1 is mounted on a vehicle and transmits ultrasonic waves at the bottom of a tank 200 that stores liquid fuel, and receives a reflected wave reflected by the liquid surface to obtain the liquid level. Is a device for detecting the position of In addition, about a part of liquid level detection apparatus 100 shown in FIG. 1, in order to show an internal structure intelligibly, it has shown not the cross section but the side. The liquid level detection apparatus 100 roughly includes two functional units, specifically, a sensor unit 1 and a housing unit 2 from the functional viewpoint.

The sensor unit 1 is an assembly that functions as a transmitter and receiver of ultrasonic waves as a whole. The sensor unit 1 includes an ultrasonic oscillation element 11, two internal terminals 13, an elastic body 14, a case 15, a lid 16, and two external terminals 17.

The ultrasonic wave oscillation element 11 is an element that transmits and receives an ultrasonic wave. The ultrasonic oscillation element 11 is formed in a disk shape by a substance having a piezoelectric effect such as PZT (zirconate titanate). The piezo effect is a characteristic in which a volume changes when a voltage is applied, and a voltage is generated when an external force is applied. Electrodes printed on substantially the entire surface of the ultrasonic oscillation element 11 are provided on both sides. The ultrasonic oscillation element 11 vibrates in the direction of the central axis A, which is the thickness direction, by the above-described piezo effect, when a voltage is applied between the electrodes on both surfaces from an external electric circuit through the lead wire 3. It emits ultrasonic waves. The ultrasonic oscillation element 11 is accommodated in the case 15 together with the insulating member.

The internal terminal 13 is a terminal for electrically connecting the ultrasonic oscillation element 11 and the external terminal 17. The internal terminal 13 is formed of a metal plate. The ultrasonic oscillation element 11 and the internal terminal 13 are electrically connected by soldering. In the present embodiment, two internal terminals 13 are provided on both sides of the ultrasonic oscillation element 11 and the elastic body 14.

The elastic body 14 is a substantially cylindrical member disposed coaxially with the central axis A of the ultrasonic oscillation element 11, and of the two end faces on both sides in the axial direction, the first surface is the ultrasonic oscillation element 11. The second surface is in contact with the lid 16. The elastic body 14 is formed of, for example, an elastic material such as a flexible resin and rubber.

The case 15 is a bottomed cylindrical case having a receiving chamber for receiving the ultrasonic oscillation element 11, the two internal terminals 13 and the elastic body 14.

The lid 16 is a member for closing the storage chamber of the case 15. In the state where the lid 16 is locked to the case 15, the elastic body 14 has a large dimension in the direction of the central axis A so that the elastic body 14 is compressed by the lid 16 and accommodated in the storage chamber of the case 15 in an elastically deformed state. It is designed. For this reason, the ultrasonic oscillation element 11 is fixed in a state of being pressed against the bottom surface of the case 15 by the elastic force of the elastic body 14. The internal terminal 13 is inserted through the hole provided in the lid 16, and the tip of the internal terminal 13 protrudes outside the accommodation chamber of the case 15.

The external terminal 17 is a terminal for electrically connecting the internal terminal 13 and the lead wire 3. The external terminal 17 is formed of a metal plate. One end of the external terminal 17 is joined to the tip of the internal terminal 13 by welding. The other end of the external terminal 17 is connected to the lead wire 3 by crimping or the like. The external terminal 17 is fixed to the lid 16 outside the accommodation chamber of the case 15.

Next, the housing portion 2 will be described. The housing part 2 is an assembly which functions as a propagation path of an ultrasonic wave as a whole by having a propagation path which propagates an ultrasonic wave inside. As shown in FIG. 1, the housing portion 2 has a body 21, a guide pipe 22, a guide pipe 23 and a reflection plate 24.

The body 21 is a resin member that holds and fixes the sensor unit 1, the guide pipe 22, the guide pipe 23, and the reflection plate 24. The guide pipe 22, the guide pipe 23 and the reflecting plate 24 are attached to the body 21. The body 21 is fixed to the bottom of the tank 200. In the sensor unit 1, a gap 8 is provided between the case 15 and the inner surface of the body 21 such that the central axis A of the ultrasonic oscillation element 11 is coaxial with the central axis of the guide pipe 22. It is attached to the body 21 so as to be arranged.

The guide pipe 22 is a metal cylinder made of a substantially truncated cone. One end side of the guide pipe 22 corresponding to the right side in FIG. 1 is provided at a position facing the sensor unit 1. The guide pipe 22 has a circular cross section in the direction orthogonal to the central axis A of the guide pipe 22. The guide pipe 22 forms a first path 4 which is a part of a propagation path, which extends horizontally from the position where the ultrasonic oscillation element 11 is provided. The first path 4 has a conical portion 41, a straight portion 42 and a step 43. The conical portion 41 is a frusto-conical portion whose cross-sectional area gradually reduces as it is separated from the ultrasonic oscillation element 11. In other words, the diameter of the cross section of the conical portion 41 in the direction orthogonal to the central axis A decreases as the distance from the ultrasonic oscillation element 11 increases. The straight portion 42 is a portion having a constant cross-sectional area, that is, a straight tube. The stepped portion 43 is a portion connecting the conical portion 41 and the linear portion 42, and the cross-sectional area of the conical portion 41 is reduced in a step-like manner at the end opposite to the end where the ultrasonic wave oscillation element 11 is provided. It is a part. An annular reference surface 221 coaxial with the central axis A is formed on the guide pipe 22 by the presence of the step 43.

The guide pipe 23 is a straight tubular metal cylinder. The guide pipe 23 is provided such that the central axis B of the guide pipe 23 is orthogonal to the central axis A, and is continuous with the end of the guide pipe 22 on the linear portion 42 side via the body 21. The guide pipe 23 has a circular cross section in the direction orthogonal to the central axis B. The upper end portion of the guide pipe 23 is positioned so as to protrude upward by a predetermined length than the liquid level at the maximum time of the fuel storage amount of the tank 200. The guide pipe 23 forms a second path 5 which is a part of the propagation path. The second path 5 extends from the bottom of the tank 200 upward, in the vertical direction in the present embodiment. The diameter of the second path 5 in the present embodiment is equal to the diameter of the straight portion 42.

The reflecting plate 24 is a metal plate. The reflection plate 24 is disposed so that the central axis A of the guide pipe 22 and the central axis B of the guide pipe 23 intersect at the reflection surface 241 of the reflection plate 24 in a state of being held and fixed to the body 21 There is. The reflection plate 24 reflects the ultrasonic wave transmitted from the ultrasonic oscillation element 11 toward the liquid surface of the fuel. Specifically, the reflection plate 24 reflects the ultrasonic wave traveling along the central axis A of the guide pipe 22 in the direction in which the incident angle to the liquid surface is 0 °, that is, in the direction orthogonal to the liquid surface. As installed. In the present embodiment, the reflection plate 24 is provided to be inclined 45 ° with respect to the liquid surface.

With the above configuration, when a pulse voltage is applied to the ultrasonic oscillation element 11 through the lead wire 3, the external terminal 17 and the internal terminal 13, the ultrasonic oscillation element 11 vibrates, and the bottom surface of the case 15 is Ultrasonic waves are transmitted to the first path 4 via the first path 4. When the sensor unit 1 receives a reflected wave reflected on the liquid surface through the reflection plate 24 or a reflected wave reflected on the reference surface 221, the pressure action causes the bottom of the case 15 to vibrate, and the ultrasonic oscillation element 11 also accordingly Vibrate. Thereby, the ultrasonic oscillation element 11 generates a voltage, and the voltage is input as an output signal to an external electric circuit through the internal terminal 13, the external terminal 17 and the lead wire 3. Since the distance from the ultrasonic oscillation element 11 to the reference surface 221 is predetermined, the fuel is based on the time from the transmission of the ultrasonic wave by the ultrasonic oscillation element 11 to the reception of the reflected wave reflected by the reference surface 221. The propagation velocity of the ultrasonic wave in the inside can be measured. Therefore, by using the reflected wave reflected by the reference surface 221 as a reference wave for calculating the position of the liquid level, the position of the liquid level can be highly accurate regardless of the change in the propagation velocity of the ultrasonic wave due to the temperature change of the liquid. Can be detected.

Here, as shown in FIGS. 1 to 3, the housing portion 2 has a passage air vent hole 6 in the vicinity of the step portion 43 and in the upper part in the vertical direction, which is the uppermost part in the vertical direction in this embodiment. Here, the vertically uppermost portion is the highest position in the vertical direction in a cross section perpendicular to the central axis A of the first path 4, in other words, right above the central axis A of the first path 4. It is a position. However, the passage air vent may not necessarily be provided at the uppermost in the vertical direction, and may be provided, for example, at a position slightly offset from the uppermost in the vertical direction. The passage air vent hole 6 is a circular through hole communicating the inside and the outside of the housing portion 2. The size of the passage air vent hole 6 is preferably at least 1 mm in diameter so that the air accumulated in the inside of the housing part 2 can escape to the outside of the housing part 2. However, the size of the passage air vent hole 6 is 5% or less of the inner circumferential area of the portion forming the first passage 4 in the housing portion 2 in consideration of securing a predetermined strength in the housing portion 2, the present embodiment In the configuration of the form, for example, the diameter is preferably 8 mm or less. In the present embodiment, the diameter of the passage air vent 6 is designed to be 3 mm. The vicinity of the step portion 43 means that the shortest distance from the reference surface 221 along the inner surface of the housing portion 2 is in the range within a predetermined value. The predetermined value referred to here is the maximum value that can exert the effect that the air accumulated in the step portion 43 escapes from the passage air vent hole 6 to the outside of the housing portion 2. In the present embodiment, the passage air vent hole 6 is provided at a position higher in the vertical direction than the step 43 in the conical portion 41, and the reference surface 221 along the inner surface of the housing portion 2 and the end of the passage air vent hole 6 The shortest distance with is designed to be 3 mm. For example, as shown in FIG. 4, the housing portion 2 may have the passage air vent hole 6 a not in the vicinity of the step 43 but in the step 43. The configuration in which the passage air vent hole 6 a is provided in the step portion 43 means a configuration in which at least a part of the passage air vent hole 6 a is provided in the reference surface 221 on the inner surface of the housing portion 2.

Further, as shown in FIGS. 1, 2 and 5, the housing portion 2 is provided with a housing air vent hole in the upper portion 9, which is a portion located vertically above the gap 8 between the inner surface of the housing portion 2 and the case 15. Have seven. That is, the upper portion 9 is a portion of the housing portion 2 in which the gap 8 is projected in the vertical direction. The housing air vent hole 7 is a circular through hole communicating the inside and the outside of the housing portion 2. The size of the housing air vent hole 7 is preferably 1 mm or more in diameter so that the air accumulated in the inside of the housing part 2 can escape to the outside of the housing part 2. In the present embodiment, the diameter of the housing air vent 7 is designed to be 3 mm. The configuration in which the housing air vent hole 7 is provided in the upper portion 9 means that at least a part of the housing air vent hole 7 is provided in the upper portion 9 on the inner surface of the housing portion 2. The housing portion 2 may have a housing air vent 7 in the vicinity of the upper portion 9 instead of the upper portion 9. The vicinity of the upper portion 9 means that the shortest distance from the upper portion 9 along the inner surface of the housing portion 2 is within a predetermined value. The predetermined value referred to here is the maximum value that can exert the effect that the air staying in the gap 8 escapes from the housing air vent 7 to the outside of the housing part 2 and is, for example, 3 mm as a standard.

[1-2. effect]
According to the first embodiment described above, the following effects can be obtained.

(1a) The passage air vent hole 6 is provided in the vicinity of the step 43 which is a place where air tends to stagnate. Therefore, the air stagnating in the step 43 is likely to escape from the passage air vent hole 6 to the outside of the housing 2 if it is. For this reason, it is possible to make the air difficult to stay in the step 43. As a result, it is possible to make it difficult to cause a decrease in the detection accuracy of the position of the liquid surface due to the stagnation of air in the step 43.

(1b) The passage air vent hole 6 is provided in the vicinity of the step 43 at the conical portion 41. According to such a configuration, for example, as shown in FIG. 4, the processability at the time of manufacture can be improved as compared with the configuration having the passage air vent hole 6 a in the step 43.

(1c) A housing air vent hole 7 is provided in an upper portion 9 located vertically above the gap 8 where air tends to stay. Therefore, air which would otherwise be retained in the gap 8 would easily escape from the housing air vent 7 to the outside of the housing part 2. For this reason, it is possible to make the air difficult to stay in the gap 8. Further, since the gap 8 is a narrow space, when the liquid adheres to the gap 8, the liquid closes the gap 8, and air tends to be retained in the space below the gap 8 in the housing portion 2. However, according to the configuration of the present embodiment, air that is originally retained in the space below the gap 8 is likely to escape from the housing air vent hole 7 to the outside of the housing portion 2, like air that is retained in the gap 8. As a result, it is possible to prevent anomalous reflection caused by the reflected wave that is reflected inside the housing portion 2 from the gap 8 and air staying in the space below the gap 8.

In the present embodiment, the housing portion 2 corresponds to a housing, and the upper portion 9 corresponds to a portion positioned vertically above the gap.

[2. Second embodiment]
[2-1. Constitution]
As shown in FIGS. 6 to 10B, the second embodiment is different from the liquid level detection device 100 of the first embodiment in that the liquid level detection device 100c includes the path hole cover 25 and the housing hole cover 26. In addition, since the basic configuration of the liquid level detection apparatus 100c is the same as that of the first embodiment, the same reference numerals are used for configurations common to the first embodiment, and the description thereof is omitted, and is different from the first embodiment. Description will be made focusing on the configuration.

As shown in FIGS. 6 to 9, the housing portion 2c has a passage air vent hole 6c and a groove 61c.

The passage air vent hole 6 c is a hole provided in the guide pipe 22. The passage air vent hole 6c is circular when viewed from above in the vertical direction.

The groove 61 c is a groove provided on the upper surface of the body 21 along the width direction of the housing portion 2 c which is perpendicular to the central axis A and parallel to the horizontal direction. The groove 61c has a trapezoidal shape as viewed from above in the vertical direction, and is recessed in a U shape as viewed from the side. The height of the bottom surface of the groove 61c is constant in the width direction of the housing portion 2c. The groove 61 c is open at the central portion in the bottom surface in the width direction of the housing portion 2 c so as to communicate with the first path 4. The groove 61c is formed at a position where a portion of the guide pipe 22 where the passage air vent 6c is provided is exposed, and communication between the passage air vent 6c and the groove 61c allows communication between the inside and outside of the housing portion 2c. The groove 61 c is formed larger than the diameter of the passage air vent 6 c in the direction along the central axis A. In addition, about the position in which the path | pass air vent hole 6c is provided, a magnitude | size, etc., it is the same as that of the path air vent hole 6 of 1st Embodiment.

The liquid level detection device 100c includes a passage hole cover 25 covering the passage air removal hole 6c above the passage air removal hole 6c in the vertical direction. The passage hole cover 25 has such a size that the passage air vent hole 6c is accommodated when viewed from above in the vertical direction. The passage hole cover 25 is provided so as to have a space 251 for releasing the air from the passage air vent hole 6c between the housing portion 2c and the portion of the housing portion 2c where the passage air vent hole 6c is formed. In the present embodiment, the passage hole cover 25 is integrally formed with the body 21 of the housing portion 2c, and has a ceiling portion 252 and two

support portions

253 and 254.

The ceiling portion 252 is a rectangular flat portion when viewed from above in the vertical direction. The ceiling portion 252 has a size in which the passage air vent hole 6c is accommodated when viewed from above in the vertical direction, that is, the passage air vent hole 6c does not protrude.

The two

support portions

253 and 254 are plate-like portions extending from the two sides of the ceiling portion 252 parallel to the width direction of the housing portion 2 c to the upper surface of the body 21.

The space 251 is a space formed between the ceiling 252 and a portion of the body 21 in which the groove 61 c is formed by providing two supporting

parts

253 and 254.

Further, as shown in FIGS. 6, 7, 10A and 10B, the housing air vent hole 7c, which is a through hole communicating the inside and outside of the housing portion 2c, is the same as the housing portion 2 of the first embodiment. Have. The housing air vent hole 7 c is a hole provided in the body 21. The housing air vent hole 7c has a rectangular shape as viewed from above in the vertical direction. The position, size, etc. of the housing air vent holes 7c are the same as those of the housing air vent holes 7 of the first embodiment.

The liquid level detection device 100c is provided with a housing hole cover 26 covering the housing air removal hole 7c above the housing air removal hole 7c in the vertical direction. The housing hole cover 26 has a size in which the housing air vent hole 7c is accommodated when viewed from above in the vertical direction. The housing hole cover 26 is provided so as to have a space 261 for allowing air from the housing air vent hole 7c to escape between the housing portion 2c and the portion of the housing portion 2c where the housing air vent hole 7c is formed. In the present embodiment, the housing hole cover 26 is formed integrally with the body 21 of the housing portion 2c, similarly to the passage hole cover 25, and has a ceiling portion 262 and two

support portions

263 and 264.

The ceiling portion 262 is a rectangular flat portion when viewed from above in the vertical direction. The ceiling portion 262 has a size in which the housing air vent hole 7c is accommodated when viewed from above in the vertical direction, that is, the housing air vent hole 7c does not protrude.

The two

support portions

263 and 264 are plate-like portions extending from the two sides of the ceiling portion 262 parallel to the width direction of the housing portion 2 c to the upper surface of the body 21.

The space 261 is a space formed between the ceiling portion 262 and a portion of the body 21 in which the housing air vent hole 7 c is formed by providing the two

support portions

263 and 264.

[2-2. effect]
According to the second embodiment described above, the following effects can be obtained in addition to the effects (1a) to (1c) of the first embodiment described above.

(2a) The liquid level detection device 100c includes the passage hole cover 25 covering the passage air vent hole 6c and the housing hole cover 26 covering the housing air vent hole 7c. Thereby, it is possible to suppress foreign matter mixed in the fuel from entering through the passage air vent hole 6c and the housing air vent hole 7c. That is, foreign matter such as metal and resin is often mixed in the fuel, and the foreign matter is suspended in the fuel due to the fluctuation of the liquid level when the vehicle is traveling, but naturally sinks when the vehicle is stopped. come. For this reason, there has been a possibility that foreign matter naturally sinking from the passage air vent hole 6c and the housing air vent hole 7c may intrude. According to this point and the second embodiment, since the passage air vent 6c and the housing air vent 7c are covered by the passage hole cover 25 and the housing hole cover 26, respectively, it is possible to suppress the entry of foreign matter. For this reason, the ultrasonic wave propagated in the first path 4 is diffused, and the intensity of the liquid level detection wave is reduced, and the occurrence of abnormal reflection due to foreign matter is suppressed. Therefore, false detection can be suppressed.

[3. Other embodiments]
As mentioned above, although embodiment of this indication was described, it can not be overemphasized that this indication can take various forms, without being limited to each above-mentioned embodiment.

(3a) In the above embodiments, the configuration in which the passage air vent holes 6, 6c are provided in the conical portion 41 is exemplified. However, the position where the passage air vent is provided is not limited to this. For example, the passage air vent may be provided in the straight portion 42.

(3b) In the above embodiments, the circular path air vent holes 6, 6c, the housing air vent holes 7, and the square housing air vent holes 7c are illustrated. However, the shapes of the passage air vent hole and the housing air vent hole are not limited to this, and may be, for example, a semicircular shape, an elliptical shape, or a polygonal shape such as a triangular shape. Also for example, the path venting holes and the housing venting holes are so-called rounded rectangular shapes in which each vertex of the polygon is a round shape instead of a corner or two parallel lines of equal length and two semicircular shapes. May be Also, for example, a plurality of passage air vent holes and a plurality of housing air vent holes may be provided.

(3c) In the above embodiments, in order to facilitate the removal of the air remaining in the step 43 and the gap 8, the configuration in which the passage air removal holes 6, 6c and the housing air removal holes 7, 7c are provided in the housing 2 is illustrated. did. However, for example, only the passage air vent may be provided in the housing portion, or, for example, only the housing air vent may be provided.

Further, for example, the liquid level detection device 100b in the modification shown in FIG. 11 has slit holes 67b instead of the passage air vent hole 6 and the housing air vent hole 7 in comparison with the liquid level detector 100 of the first embodiment. The point is different. The other configuration of the liquid level detection apparatus 100b is the same as that of the liquid level detection apparatus 100 according to the first embodiment, and thus the description thereof is omitted.

The slit hole 67 b is provided at the vertically uppermost portion of the housing portion 2. The slit hole 67 b is a rectangular hole provided in a straight line from the position where the passage air vent hole 6 of the first embodiment is provided to the position where the housing air vent hole 7 is provided in the housing portion 2 b. Here, the width of the slit hole 67b is set to a predetermined length in consideration of securing a predetermined strength in the housing portion 2b. Specifically, for example, the width of the slit hole 67b is set to 5% or less of the total length of the inner circumference at the position where the cross-sectional area is the smallest among the portions forming the first path 4 in the housing portion 2b.

According to such a liquid level detection device 100b, air that would otherwise be retained inside the housing portion 2b is likely to escape from the slit hole 67b to the outside of the housing portion 2b. For this reason, it is possible to make the air less likely to stay inside the housing portion 2b.

(3d) In the second embodiment, the path hole cover 25 exemplifies the configuration having the ceiling portion 252 and the two

support portions

253 and 254, but the configuration of the path hole cover is limited to this. is not. For example, the passage hole cover 25 may not have the two

support portions

253 and 254. Specifically, the passage hole cover corresponding to the ceiling 252 has a space similar to the space 251 for escaping the air from the passage air vent hole 6c between the housing portion and the portion where the passage air vent hole 6c is formed. Provided without having That is, the passage hole cover is provided to abut on the upper surface of the body 21. In this example, the air from the passage air vent 6c escapes through a U-shaped recessed portion as viewed from the side surface of the groove 61c communicating with the passage air vent 6c.

Also, for example, as shown in FIGS. 12A and 12B, even if the path hole cover 25d has a ceiling portion 252d, two

support portions

253d and 254d, and three plate portions 255d to 257d. Good. Specifically, the passage hole cover 25d is provided so as to have a space 251d for escaping the air from the passage air vent hole 6d between the housing portion 2d and the portion of the housing portion 2d where the passage air vent hole 6d is formed. The space 251 d is divided by three plate portions 255 d to 257 d. The three plate portions 255d to 257d are formed between the two

support portions

253d and 254d at intervals so as to be arranged in a comb shape when viewed from the side. In this example, the passage air vent hole 6d has a rounded rectangular shape. In addition, the ceiling portion 252d has a size in which the passage air removal hole 6d and the groove 61d are accommodated when viewed from above in the vertical direction, that is, the passage air removal hole 6d and the groove 61d do not protrude.

Also, for example, as shown in FIGS. 13A and 13B, the path hole cover 25e may have a mesh ceiling portion 252e. The ceiling 252 e has a net shape of such a degree that the foreign matter can not pass through. In this example, the air from the passage air vent hole 6c escapes from the ceiling 252e, so a plate-like portion extending to the upper surface of the body 21 also at two sides of the ceiling 252e where the two supporting

portions

253 and 254 are not provided. May be included. That is, the route hole cover 25e may be configured such that the ceiling portion 252e is supported on all four sides of the ceiling portion 252e. In addition, the support portion may also be in the form of a net.

(3e) In the second embodiment, the path hole cover 25 has a flat plate-like ceiling portion 252, but the shape of the path hole cover 25 is not limited to this.

For example, as shown in FIGS. 14A and 14B, the path hole cover 25f may have a plate-like configuration curved so as to be convex upward in the vertical direction. The passage hole cover 25f is U-shaped as viewed from the side. The passage hole cover 25f is provided so as to have a space 251f for releasing the air from the passage air vent hole 6c between the housing portion 2f and the portion of the housing portion 2f where the passage air vent hole 6c is formed. The passage hole cover 25 f is integrally formed with the body 21 at both ends along the central axis A. In such a configuration, foreign matter that naturally sinks down more easily than in a configuration where the ceiling portion is flat, it is possible to suppress accumulation of foreign matter in the passage hole cover.

Also, for example, as shown in FIGS. 15A and 15B, the path hole cover 25g may have a triangular plate shape that is convex upward in the vertical direction. The passage hole cover 25g is provided so as to have a space 251g for releasing the air from the passage air vent hole 6c between the housing portion 2g and the portion of the housing portion 2g where the passage air vent hole 6c is formed. Even with such a configuration, the foreign matter that naturally sinks is more likely to fall as compared with the flat configuration of the ceiling portion, so that the foreign matter can be prevented from collecting in the passage hole cover.

(3f) In the second embodiment, the passage hole cover 25 integrally formed with the body 21 in the housing portion 2c is illustrated. However, the passage hole cover may be configured separately from the housing portion. For example, the passage hole cover may be a dedicated part that is retrofitted to the housing part. Also, for example, the passage hole cover may be configured to be provided to an accessory different from the liquid level detection device 100c. Specifically, for example, the passage hole cover is attachable or integrally formed to a fuel pump module or a bracket or the like for mounting the fuel pump module (not shown). When the fluid level detection device 100c is mounted in the tank 200, the passage hole cover, which can be attached to or integrally formed with the fuel pump module or the bracket, is disposed vertically above the passage air vent hole.

In the above (3d) to (3f), although the modification of the passage hole cover has been described, the same configuration may be applied to the housing hole cover.

(3g) In the above embodiments, the liquid

level detection devices

100 and 100c used for detecting the liquid level of the fuel in the tank 200 are illustrated. However, the application of the liquid level detection device is not particularly limited. The liquid level detection device may be used to detect the level of other liquids mounted on a vehicle, such as engine oil, brake fluid, and window washer liquid. Further, for example, the liquid level detection device may be used for liquid level detection in a liquid transport tank provided in a liquid transport vehicle or in a liquid container of various consumer devices other than the vehicle.

(3h) The function of one component in each of the above embodiments may be distributed as a plurality of components, or the function of a plurality of components may be integrated into one component. In addition, part of the configuration of the above embodiment may be omitted. In addition, at least a part of the configuration of the above-described embodiment may be added to or replaced with the configuration of the other above-described embodiment.

Claims

A liquid level detection device (100, 100b, 100c) for detecting the position of the liquid level, comprising
An ultrasonic oscillator (11) capable of transmitting and receiving ultrasonic waves;
A housing (2, 2b to 2d, 2f, 2g) internally having a propagation path through which ultrasonic waves propagate;
Equipped with
The propagation path is
A first path (4) extending horizontally from the position where the ultrasonic oscillation element is provided;
And a second path (5) extending upward from the end opposite to the position where the ultrasonic oscillation element is provided in the first path,
The first path is
A reduction section (41) whose cross-sectional area gradually reduces as it is separated from the ultrasonic wave oscillation element;
And a step (43) in which the cross-sectional area is reduced in a step-like manner at the end of the reduction portion;
The liquid level detection device, wherein the housing has a passage air vent hole (6, 6a, 6c, 6d) communicating the inside and the outside of the housing at an upper end in the vicinity of the step or the step.
The liquid level detection device according to claim 1, wherein
The passage air vent hole is a circle having a diameter of 1 mm or more.
The liquid level detection device according to claim 1 or 2, wherein
The liquid level detection device according to claim 1, wherein the vicinity of the step portion is a range within 3 mm from the step portion.
The liquid level detection device according to any one of claims 1 to 3, wherein
The liquid level detection device according to claim 1, further comprising a passage hole cover (25, 25d to 25g) covering the passage air removal hole vertically above the passage air removal hole.
The liquid level detection device according to claim 4, wherein
The fluid level detection device according to claim 1, wherein the passage hole cover has a size in which the passage air vent hole is accommodated when viewed from above in the vertical direction.
The liquid level detection device according to claim 4 or 5, wherein
The passage hole cover is provided so as to have a space (251, 251d, 251f, 251g) for escaping air from the passage air vent hole between a portion of the housing where the passage air vent hole is formed. , Liquid level detection device.
The liquid level detection device according to any one of claims 1 to 6, wherein
It further comprises a case (15) for housing the ultrasonic oscillation element,
The case is disposed inside the housing with a gap (8) between the case and the inner surface of the housing.
A liquid level detection device, wherein the housing has a housing air vent hole (7, 7c) communicating the inside and the outside of the housing in a portion (9) located vertically above the gap or in the vicinity of the portion.
A liquid level detection device (100, 100b, 100c) for detecting the position of the liquid level, comprising
An ultrasonic oscillator (11) capable of transmitting and receiving ultrasonic waves;
A housing (2, 2b to 2d, 2f, 2g) internally having a propagation path through which ultrasonic waves propagate;
A case (15) for housing the ultrasonic oscillation element;
Equipped with
The propagation path is
A first path (4) extending horizontally from the position where the ultrasonic oscillation element is provided;
And a second path (5) extending upward from the end opposite to the position where the ultrasonic oscillation element is provided in the first path,
The case is disposed inside the housing with a gap (8) between the case and the inner surface of the housing.
The liquid level detection device, wherein the housing has a housing air vent hole (7) communicating the inside and the outside of the housing in a portion (9) located vertically above the gap or in the vicinity of the portion.
A liquid level detection device according to claim 7 or 8, wherein
The liquid level detection device according to claim 1, further comprising: a housing hole cover (26) covering the housing air vent hole vertically above the housing air vent hole.
The liquid level detection device according to claim 9, wherein
The liquid level detection device according to claim 1, wherein the housing hole cover has a size in which the housing air vent hole is accommodated when viewed from above in the vertical direction.
The liquid level detection device according to claim 9 or 10, wherein
The housing level cover is provided so as to have a space (261) for escaping air from the housing venting hole between the housing and a portion of the housing where the housing venting hole is formed.