JP4908335B2 - Liquid state detection sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid state detecting sensor that has a liquid concentration detecting element and can appropriately discharge air bubbles having entered an enclosing region and reduce the influence of the air bubbles on concentration detection or the like. <P>SOLUTION: The sensor 1 includes a concentration sensor element 51, a holder member 55 for holding the tip 511 thereof in a state where the tip 511 is projected from an element holding hole 55H4 of itself, and a protector 58. The protector 58 is provided with a liquid circulation hole 58H1 or the like allowing liquid to circulate inside and outside the enclosing region EH. The holder member 55 has a tip surface 554S that faces the enclosing region EH and is orthogonal to the axis AX, and a tapered outer peripheral surface 554T whose diameter increases toward the base end side. In the circulation holes 58H1-58H4, own base end side ends 58H1K-58H4K are located higher than a hole rim 55H4F of the element holding hole 55H4, and the tip side ends 58H1S-58H4S are located lower than the base end side rim 554K of the outer peripheral surface 554T. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a liquid state detection sensor that detects a liquid state, and more particularly, to a liquid state detection sensor that includes a liquid concentration detection element that detects the concentration of a specific component in a liquid.

In recent years, a NOx selective reduction catalyst (SCR) may be used in an exhaust gas purification device that reduces and renders harmless nitrogen oxide (NOx) discharged from a diesel engine, for example, an automobile equipped with a diesel engine. In this device, an aqueous urea solution is used as the reducing agent. However, in order to effectively reduce nitrogen oxides with this device, the aqueous urea solution must be in an appropriate concentration range (range of urea concentration in the aqueous urea solution). is required.
However, even when a urea aqueous solution having an appropriate concentration is stored in the urea water tank storing the urea aqueous solution, the urea concentration may deviate from the appropriate range due to a change over time or the like. Moreover, liquids other than urea aqueous solution of appropriate urea concentration, such as tap water, may be injected into the urea water tank.
Therefore, a concentration sensor that detects the urea concentration of the urea aqueous solution is attached to the urea water tank, and when the urea concentration of the urea aqueous solution deviates from the appropriate range, a warning is issued in the event of an abnormality, and the reduction of nitrogen oxides in the exhaust gas purification device A system has been proposed that informs the driver that (purification) cannot be performed properly (see Patent Document 1).

JP 2000-371831 A

By the way, in detecting the concentration of a specific component such as urea in a liquid such as an aqueous urea solution using a liquid concentration detecting element, bubbles or a group of bubbles contained in the liquid (hereinafter, these may be collectively referred to as bubbles). May interfere with the measurement. If bubbles are in contact with the liquid concentration sensor to measure the concentration of a characteristic component in the liquid, the influence of the bubbles may interfere with the flow of the liquid around the liquid concentration sensor or measure the characteristics of the liquid. This is because a trouble such as the superimposition of images occurs.
By the way, an enclosing member may be provided around the portion of the liquid concentration detection element disposed in the liquid for the purpose of controlling the liquid flow, protecting the liquid concentration detection element, or the like. In such a configuration, when a large number of bubbles stay in the surrounding region surrounded by the surrounding member, the portion of the liquid concentration detection element that is disposed in the liquid is surrounded by the numerous bubbles. In particular, the influence of bubbles is likely to occur, for example, the density detection becomes difficult.
In some cases, an outer surrounding member is further provided around the surrounding member for the purpose of controlling the liquid flow or protecting the liquid concentration detecting element. When the liquid state detection sensor is configured in this way, it is necessary to consider not only the bubbles that have entered the surrounding region, but also the bubbles that are located between the surrounding member and the outer surrounding member.

The present invention has been made in view of such problems, and in a liquid state detection sensor including a liquid concentration detection element that detects the concentration of a specific component in a liquid, bubbles that have entered the enclosed region are appropriately detected. It is an object of the present invention to provide a liquid state detection sensor that can be discharged at a low rate and can reduce the influence on the concentration detection by bubbles.
Furthermore, in the liquid state detection sensor having the surrounding member and the outer surrounding member, not only the inside of the surrounding region but also the bubbles that have entered between the surrounding member and the outer surrounding member can be appropriately discharged, and the influence of the bubbles on the concentration detection, etc. An object is to provide a liquid state detection sensor that can be reduced.

  The solution is a liquid state detection sensor for detecting the state of the liquid, the liquid concentration detection element for detecting the concentration of the specific component in the liquid, and the tip of the liquid concentration detection element at its own element holding hole. A holder member that holds the liquid concentration detecting element in a state of protruding from the surroundings, and a surrounding member, and the protruding state of the tip portion of the liquid concentration detecting element is the gravitational direction. The surrounding member surrounds at least the periphery of the liquid concentration detecting element in the horizontal direction with a gap from the distal end, and is surrounded by the surrounding member. It is an enclosing member in which one or a plurality of flow holes through which the liquid can circulate is formed inside and outside the enclosing region, and the holder member includes any of the enclosing region surfaces facing the enclosing region. It is configured to be positioned higher than or at the same height as the lowest lowest hole periphery among the peripheral edges of the child holding holes, and at least one of the flow holes has its upper end at the lowest hole periphery. It is a liquid state detection sensor which is a bubble discharge circulation hole which is higher than the lower end and lower than the peripheral edge of the surrounding area surface.

  In the liquid state detection sensor according to the present invention, the upper end has a bubble discharge circulation hole whose upper end is higher than the lowest hole periphery of the element holding hole and whose lower end is lower than the surface periphery of the surrounding area surface. For this reason, even if bubbles in the liquid enter the enclosed region, the bubbles are discharged from the bubble discharge circulation hole to the outside of the surrounding member, and the bubbles accumulate below the height near the upper end of the bubble discharge circulation hole. Absent. Accordingly, a large number of bubbles accumulate in the surrounding area (in the surrounding member), and the bubbles come into contact with the tip of the liquid concentration detection element, or the liquid flow in the surrounding area is hindered. Problems that hinder the detection of the concentration of specific components are prevented.

The liquid state detection sensor may be any sensor that detects at least the concentration of the specific component in the liquid, and includes the liquid temperature and the liquid level in addition to the concentration of the specific component. It is good also as a composite type sensor so that it can detect.
In addition, the liquid concentration detection element may be an element configured to detect the concentration of a specific component in the liquid. However, in addition to the concentration of the specific component, the temperature of the liquid and the liquid level are the lower limit levels. It is good also as a composite type element which detects whether it was less than this.
The surrounding member only needs to surround at least the periphery of the liquid concentration detecting element in the horizontal direction with a gap from the distal end, and further surround the lower portion of the distal end. Anyway.

  Furthermore, the holder member may be configured such that any part of the surrounding area surface facing the surrounding area is positioned higher than the lowest hole periphery or at the same height as the lowest hole periphery. Specifically, a form in which the entire surrounding region surface of the holder member is located at the same height as the lowest hole periphery, that is, a form in which the entire surrounding region surface forms a horizontal plane including the hole periphery of the element holding hole. In addition, a tapered shape such as a conical shape in which the surrounding region surface becomes higher as it goes from the element holding hole toward the surface periphery, or a horizontal surface until the surrounding region surface goes from the element holding hole toward the surface periphery, and from the middle toward the surface periphery. A tapered shape with a base such as a conical shape that becomes higher is also mentioned. Also, of the surrounding area surface, the first horizontal plane until the middle from the element holding hole toward the peripheral edge of the surface, and a two-stage shape that becomes a second horizontal plane higher than the first horizontal plane to the peripheral edge again by providing a step from the middle, A multi-stage form is also mentioned. In addition, the surrounding area surface has a undulation that becomes high, low (however, higher than the lowest hole periphery) and high from the hole periphery of the element holding hole to the surface periphery of the surrounding area surface. You can also.

  Further, in the above-described liquid state detection sensor, when the holder member is compared with any part of the surrounding area surface, the part close to the surface periphery of the surrounding area surface is higher. The bubble discharge circulation hole is preferably a liquid state detection sensor whose upper end is higher than the peripheral edge of the surrounding area surface.

In the liquid state detection sensor according to the present invention, the holder member has a higher or the same height as the portion close to the peripheral edge of the surface of the surrounding region when any portion of the surrounding region surface is compared with each other. It is made into the form which is located in. In other words, regarding the surrounding area surface, when viewed along the path from the peripheral edge of the element holding hole to the peripheral edge of the surrounding area surface, either the horizontal part, the part that gradually becomes higher, or the part that suddenly becomes higher It is a form that appears. Moreover, the upper end of the bubble discharge circulation hole is higher than the peripheral edge of the surrounding area surface. The lower end is lower than the peripheral edge of the surrounding area surface.
Therefore, in this liquid state detection sensor, the bubbles that have entered the surrounding area are smoothly moved toward the peripheral edge of the surrounding area surface along the surrounding area surface of the holder member, and are moved out of the surrounding member through the bubble discharge circulation hole. Can be discharged.

  It should be noted that the holder member may be configured such that any part of the surrounding area surface is located at a high position or at the same height when the respective parts are compared with each other. . Specifically, a form in which the entire surface of the surrounding area of the holder member forms a horizontal plane including the peripheral edge of the element holding hole can be mentioned. In addition, a tapered shape such as a conical shape in which the surrounding region surface becomes higher as it goes from the element holding hole toward the surface periphery, or a horizontal surface until the surrounding region surface goes from the element holding hole toward the surface periphery, and from the middle toward the surface periphery. A tapered shape with a base such as a conical shape that becomes higher is also mentioned. Also, of the surrounding area surface, the first horizontal plane until the middle from the element holding hole toward the peripheral edge of the surface, and a two-stage shape that becomes a second horizontal plane higher than the first horizontal plane to the peripheral edge again by providing a step from the middle, A multi-stage form is also mentioned.

  Further, in the above-described liquid state detection sensor, the holder member includes an element surrounding surface around the element holding hole and a surface peripheral side of the surrounding region surface from the element surrounding surface. It is preferable that the liquid state detection sensor is configured to be positioned and include a peripheral surface of the surrounding area surface and a peripheral side surface that is higher than the peripheral surface of the element.

  In the liquid state detection sensor of the present invention, the holder member is configured to form an element peripheral surface and a peripheral peripheral surface higher than this as the surrounding region surface. In other words, since the peripheral side surface, that is, the place higher than the peripheral surface of the element is formed on the peripheral surface side of the element peripheral surface, once the bubble moves to the peripheral peripheral surface side, Hard to return to. Therefore, the air bubbles that have entered the surrounding area can be reliably moved toward the peripheral edge of the surface of the surrounding area, and can be discharged out of the surrounding member through the bubble discharge circulation hole. Thus, it is possible to further suppress the influence of bubbles in the concentration detection by the liquid concentration detection element due to bubbles.

  Or it is the above-mentioned liquid state detection sensor, Comprising: The said holder member is made into the form from which the said surrounding area surface becomes high as it approaches the surface periphery of the said surrounding area surface from the hole periphery of the said element holding hole. It may be a liquid state detection sensor.

In the liquid state detection sensor of the present invention, the holder member is configured such that the surrounding area surface becomes higher from the peripheral edge of the element holding hole toward the peripheral edge of the surrounding area surface. In other words, when the enveloping region surface is viewed along the path from the peripheral edge of the element holding hole to the peripheral surface of the enclosing region surface, either a gradually increasing portion or a stepwise increasing portion appears. It is said that.
Therefore, in this liquid state detection sensor, it is difficult for the bubbles to return to the element holding hole side once the bubbles move to the peripheral surface side of the surrounding area surface. Accordingly, the air bubbles that have entered the surrounding area can be moved more smoothly along the surface of the surrounding area toward the periphery of the surface of the surrounding area surface, and can be discharged out of the surrounding member through the bubble discharge circulation hole. Thus, it is possible to further suppress the influence of bubbles in the concentration detection in the liquid concentration detection element due to bubbles.

  Furthermore, it is a liquid state detection sensor of any one of the above-mentioned, Comprising: The said front-end | tip part of the said liquid density | concentration detection element is flat form containing a main surface and the back surface located in the back side of the said main surface. The tip portion includes a temperature rising detection portion that raises the temperature by energization, and a portion of the main surface that is included in the temperature rising detection portion is a temperature rising portion main surface. When the portion included in the temperature rise detection unit is the temperature rise unit back surface of the back surface, the surrounding member includes the flow hole including the bubble discharge flow hole, and the liquid concentration detection element. It is preferable that the liquid state detection sensor is arranged at a position not directly facing the temperature riser main surface and the temperature riser rear surface of the tip.

When liquid flows in various directions occur in the liquid, any of the flow holes of the surrounding member is
In the case where the liquid temperature detection unit faces the temperature rising part main surface and the temperature rising part back surface of the temperature rising detection part, the liquid flow that enters from the directly facing flow hole is the temperature rising part main part of the temperature rising detection part. Since the liquid flow proceeds so as to collide with the surface or the temperature raising portion back surface, the liquid flow tends to have a large influence such as hindering the temperature rising of the temperature raising detection portion.
On the other hand, in the sensor of the present invention, each flow hole of the surrounding member is arranged at a position that does not face the temperature riser main surface and the temperature riser rear surface at the tip. For example, each flow hole is disposed outside a virtual main surface projection region or a back surface projection region obtained by projecting the temperature rising portion main surface or the temperature rising portion back surface at the tip in the thickness direction. For this reason, since the generation of a liquid flow that proceeds so as to collide with the main surface or the back surface of the tip portion is prevented, it is possible to reduce the influence of such a liquid flow preventing the temperature increase of the temperature increase detection unit, etc. The liquid concentration can be accurately detected.

  Furthermore, in the liquid state detection sensor according to any one of the above, the surroundings of the tip of the liquid concentration detection element in the horizontal direction and the surroundings of the surrounding member in the horizontal direction are the surrounding member. An outer surrounding member that surrounds with a gap, and an intervening member interposed between the surrounding member and the outer surrounding member, the outer surrounding member being disposed between the outer surrounding member and the surrounding member. There is one or a plurality of outer flow holes through which the liquid can flow between an outer surrounding region and the outside in the horizontal direction of the outer surrounding member, and the interposition member is located above the outer surrounding region. A lower surface of the intervening member facing the outer surrounding region, and at least one of the outer circulation holes is a bubble discharge outer circulation hole whose upper end is higher than the upper end of the bubble discharge circulation hole, The lower surface of the interposition member is At least the discharge hole corresponding part located on the outer side in the horizontal direction of the bubble discharge circulation hole among the inner peripheral edge part thereof is higher than the upper end of the corresponding bubble discharge circulation hole, and at least Of the outer peripheral edge portions, the outer discharge hole corresponding portions located on the inner side in the horizontal direction of the bubble discharge outer circulation hole are all higher than the lower ends of the corresponding bubble discharge outer circulation holes, and are located in the surrounding region. At least a part of the bubble group that has entered and is discharged from the bubble discharge circulation hole is from the discharge hole corresponding part from the upper end of the bubble discharge circulation hole corresponding to the discharge hole corresponding part of the lower surface of the interposed member. The liquid state detection sensor may be configured to be movable along the higher part to the outer discharge hole corresponding part.

In the liquid state detection sensor of the present invention, any one of the discharge hole corresponding portions on the lower surface of the interposition member of the interposition member is higher than the upper end of the bubble discharge circulation hole corresponding to itself. When this sensor is used for detecting the state of the liquid, specifically, in a posture in which the protruding direction of the tip of the liquid concentration detecting element is the direction of gravity, the tip of the liquid detecting element, the surrounding member, the outer surrounding member, and Consider a case where the interposition member is immersed in the liquid. In this case, it is possible to easily discharge the bubbles (bubble groups) from the bubble discharge circulation hole to the outer surrounding region.
Further, at least one of the outer circulation holes is a bubble discharge outer circulation hole whose upper end is higher than the upper end of the bubble discharge circulation hole. Further, any one of the outer discharge hole corresponding portions on the lower surface of the interposed member of the interposed member is also higher than the lower end of the bubble discharge outer circulation hole corresponding to itself. For this reason, without causing the air bubbles that have reached the outer discharge hole corresponding part to flow back to the bubble discharge flow hole side of the surrounding member, from the bubble discharge outer flow hole corresponding to the outer discharge hole corresponding part, Can be discharged.

  In addition, the lower surface of the intervening member of the intervening member is such that at least a part of the bubble group extends from the discharge hole corresponding portion to a position higher than the upper end of the bubble discharge circulation hole corresponding to the discharge hole corresponding portion of the lower surface of the intervening member. Therefore, the bubbles (bubbles) discharged from the surrounding member to the outer surrounding region (the discharging hole corresponding portion on the lower surface of the interposition member) from the surrounding member through the bubble discharging circulation hole, It can be moved to the outer discharge hole corresponding portion on the lower surface of the interposition member without backflowing (reversing) in the surrounding region. After that, as described above, the bubbles (bubble groups) can be discharged through the bubble discharge outer circulation holes.

Thus, in the present invention, even when the outer member is provided in addition to the surrounding member, the bubbles (bubbles) that have entered the surrounding member are moved outside the outer member (outer surrounding region), and further to the outer side. Since it can discharge | emit to the outside of an enclosing member, the influence with respect to the density | concentration detection etc. by a bubble can be reduced.
Similarly, the air bubbles that have directly entered the outer surrounding region can be discharged from the outer discharge hole corresponding portion on the lower surface of the interposition member of the interposition member to the outside of the outer envelopment member through the air bubble discharge outer circulation hole. In addition, it is possible to prevent bubbles from entering the enclosed region through the bubble discharge circulation hole.

The outer surrounding member only needs to surround at least the horizontal direction of the front end portion of the liquid concentration detection element and the surrounding member with a gap from the surrounding member. It is good also as a form which surrounds a front-end | tip part and an enclosure member from the downward direction.
The interposition member is a member interposed between the enclosing member and the outer enclosing member, and may be composed of a plurality of members. Accordingly, the lower surface of the surrounding member may be constituted by a plurality of members.

The interposed member lower surface of the interposed member enters the enclosed region, and at least a part of the bubbles discharged from the bubble discharge circulation hole corresponds to the discharge hole corresponding portion of the lower surface of the interposed member from the discharge hole corresponding portion. It is made into the form which can move to the outside discharge hole corresponding part along the site | part higher than the upper end of the said discharge | circulation through-hole.
As a specific form of such an interposition member lower surface, for example, the form in which the entire interposition member lower surface including the discharge hole corresponding portion and the outer discharge hole corresponding portion are located at the same height, that is, the entire interposition member lower surface, The form which makes a horizontal surface including a discharge hole corresponding part and an outer discharge hole corresponding part is mentioned. In this case, the entire lower surface of the interposed member including the discharge hole corresponding portion is higher than the upper end of the bubble discharge circulation hole, and the entire lower surface of the interposed member including the outer discharge hole corresponding portion is lower than the lower end of the bubble discharge outer circulation hole. And In addition, a tapered shape that forms a conical surface that becomes higher as the bottom surface of the intervening member moves from the inner peripheral edge to the outer peripheral edge, or a horizontal plane until the intermediate member lower surface moves from the inner peripheral edge to the outer peripheral edge, The taper shape with a base which comprises the conical surface etc. which become high as it goes to the periphery is also mentioned. Further, on the lower surface of the intervening member, the first horizontal plane is formed from the inner periphery to the outer peripheral edge, while a step is provided from the middle, and the second horizontal plane higher than the first horizontal plane is formed again from the intermediate edge to the outer periphery. A multi-stage form is also included. In the above three examples, the entire bottom surface of the interposed member is tapered, tapered with a base, and a multistage shape, and the entire outer peripheral edge portion of the lower surface of the interposed member is higher than the inner peripheral edge. However, in addition to this, a part of the outer peripheral edge, for example, each outer discharge hole corresponding part or each outer discharge hole corresponding part and only its peripheral part is tapered (conical surface) or stepped so that it is higher than the others. Also mentioned. In addition, there is also a grooved configuration in which a path (groove) for moving bubbles from the discharge hole corresponding part to the outer discharge hole corresponding part is made higher than both banks along this path.
In addition, as described above, the lower surface of the interposed member corresponds to the outer discharge hole from the discharge hole corresponding portion along the portion higher than the upper end of the bubble discharge circulation hole corresponding to the discharge hole corresponding portion of the lower surface of the interposed member. It can be moved to the part. Therefore, a part of the lower surface of the interposed member may be lower than the upper end of the bubble discharge circulation hole. In addition, when viewed from the discharge hole corresponding part to the outer discharge hole corresponding part, the route along the part higher than the upper end of the bubble discharge circulation hole corresponding to the discharge hole corresponding part, It is also possible to adopt a form in which undulations that are lower (however, higher than the upper end of the bubble discharge circulation hole) and higher are generated.

  Furthermore, in the above-described liquid state detection sensor, it is preferable that the interposed member lower surface of the interposed member is a liquid state detection sensor in which any part is higher than the upper end of the bubble discharge circulation hole.

  In the liquid state detection sensor of the present invention, the entire lower surface of the interposed member is higher than the upper end of the bubble discharge circulation hole. For this reason, the bubble (bubble group) discharged | emitted from the bubble discharge | circulation through-hole can be once hold | maintained to the whole upper part of an outer surrounding area | region so that it may contact the interposition member lower surface. For this reason, it is possible to reliably discharge the bubbles from the bubble discharge circulation hole while preventing the bubbles from flowing back into the surrounding member from the bubble discharge circulation hole.

  Furthermore, in the liquid state detection sensor according to any one of the above, the lower surface of the interposed member of the interposed member includes at least the outer discharge hole corresponding portion of the outer peripheral edge portion of the interposed member from the inner peripheral edge portion. It is preferable to use a liquid state detection sensor that is also high.

  In the liquid state detection sensor of the present invention, at least the outer discharge hole corresponding part of the outer peripheral edge of the lower surface of the interposed member is higher than the inner peripheral edge. The delivered bubbles (bubble group) are unlikely to return to the inner peripheral edge on the lower side and further into the surrounding member. Thus, the bubbles near the outer discharge hole corresponding part can be more reliably discharged through the bubble discharge outer circulation hole to the outside of the outer surrounding member, so that the influence of the bubbles on concentration detection and the like can be reliably prevented.

  In addition, as for the lower surface of the interposition member, at least the outer discharge hole corresponding part among the outer peripheral edges of the intervening member only needs to be higher than the inner peripheral edge. Therefore, among the outer peripheral edge portions, only the outer discharge hole corresponding portions or the respective outer discharge hole corresponding portions and their peripheral portions are tapered or stepped so as to be higher than others. In addition, as described above, the entire lower surface of the interposed member may be made higher than the inner peripheral edge, for example, the entire lower surface of the interposed member may have a tapered shape, a tapered shape with a base, or a multi-stage shape. it can.

(Embodiment 1)
An embodiment of a liquid state detection sensor embodying the present invention will be described with reference to FIGS.

The liquid state detection sensor 1 (hereinafter also referred to as a sensor) according to the first embodiment reduces, for example, nitrogen oxide (NOx) contained in an exhaust gas of an automobile equipped with a diesel engine or the like with a urea aqueous solution NL. In the exhaust gas purifying apparatus to be detoxified, the exhaust gas purifying apparatus is used for an apparatus for detecting the concentration of the urea aqueous solution NL stored in the storage tank and the liquid level NLH of the urea aqueous solution NL.
The liquid state detection sensor 1 includes a base 2 and a sensor unit 3 extending downward from the base 2 in FIG. The liquid state detection sensor 1 has a base 2 attached around an opening of a storage tank (not shown) that stores an aqueous urea solution NL, and the sensor unit 3 is in a posture that extends in the gravity direction G. The sensor unit 3 is used by being immersed in the urea aqueous solution NL.
Therefore, in the present specification, in the description of the sensor 1 and each component, in the direction (axial direction) along the axis AX shown in FIG. 1, the upper side in FIG. To do.
Further, when specifying or describing a part related to the posture of the sensor 1 or the gravity direction G, the direction in which the sensor unit 3 extends with respect to the base 2 (the direction along the axis AX shown in FIG. 1 (axis direction)). The orientation with the gravity direction G as the downward direction) will be described as a basis. Therefore, for example, the sensor unit 3 is on the lower side (lower side) than the base unit 2, and conversely, the base unit 2 is in the direction opposite to the gravity direction G, that is, the higher side (upper side) than the sensor unit 3. ).

  Of the liquid state detection sensor 1, the base portion 2 includes a mounting flange portion 21, a lid body 25, a wiring board 22 surrounded by them, an external connection cable 24, and a bush 23 that holds this. The sensor unit 3 includes a double cylindrical liquid level sensor unit 4 and a liquid concentration sensor unit 5 which is positioned on the distal end side and positioned on the lower level side during use.

  First, the base 2 will be described. The mounting flange 21 is made of metal, and is used as a pedestal for mounting the liquid state detection sensor 1 on the periphery of the opening of a storage tank (not shown). A bolt insertion hole (not shown) is formed in the mounting flange 21 so that the liquid state detection sensor 1 (base 2) can be fixed to the storage tank with a bolt.

On the other hand, the wiring board 22 indicated by a broken line in FIG. 1 is disposed at a position higher than the mounting flange 21. A control circuit including a CPU, an electric circuit, and the like is formed on the wiring board 22, and is electrically connected to the liquid level sensor unit 4 and the liquid concentration sensor unit 5 and via an external connection cable 24. It can be connected to an external electric circuit. Further, the wiring board 22 is covered with a lid body 25 attached to the attachment flange portion 21, and is protected liquid-tightly.
The control circuit formed on the wiring board 22 is based on an output signal corresponding to the resistance value of the internal heater wiring 518 by energizing the concentration sensor element 51 shown in FIG. Specifically, the concentration of the urea aqueous solution NL is detected based on a potential difference (voltage value) generated at both ends of the internal heater wiring 518 by passing a predetermined current through the concentration sensor element 51.

Next, the sensor unit 3 will be described. As described above, the sensor unit 3 includes the liquid level sensor unit 4 and the liquid concentration sensor unit 5. Among these, first, the liquid level sensor unit 4 will be described, and then the liquid concentration sensor unit 5 will be described.
As shown in FIG. 1, the liquid level sensor unit 4 is disposed in a cylindrical outer cylinder 41 extending in a direction (axial direction) along the axis AX, and the outer cylinder 41 is coaxial. An inner cylinder 42 having a relatively small diameter and a cylindrical shape. The inner peripheral surface of the outer cylinder 41 and the outer peripheral surface of the inner cylinder 42 are separated from each other with a predetermined interval.

Of these, the outer cylinder 41 is made of metal and serves as one electrode for detecting the liquid level. The outer cylinder 41 has a narrow and elliptical slit 41S whose longitudinal direction is the direction of the axis AX, and can accommodate the urea aqueous solution NL in a state communicating with the outside between the inner cylinder 42 and the outer cylinder 41. It is like that. Moreover, while the front end 41T (lower end in FIG. 1) of the outer cylinder 41 opens, the base end (upper end in the figure) is fixed to the mounting flange 21 by welding or the like.
In the sensor 1 according to the first embodiment, the outer cylinder 41 is welded to the mounting flange 21. Further, the mounting flange 21 is connected to the ground potential in the control circuit formed on the wiring board 22, thereby setting the outer cylinder 41 to the ground potential.
Further, a rubber bush 56 described later is interposed between a front end portion 411 located on the front end side of the outer cylinder 41 and a front end portion 421 located on the front end side of the inner cylinder 42. The front end portion 411 of the outer cylinder 41 has a plurality of holding holes 41H in the circumferential direction for engaging with the engaging protrusions 562 of the rubber bushing 56 and holding the rubber bushing 56 (liquid concentration sensor unit 5). They are formed at predetermined positions (three places in the first embodiment) (see FIGS. 1 and 3). Further, three flow holes 41R are formed on the front end side of the holding hole 41H so as to allow the urea aqueous solution NL to flow there between.

  The inner cylinder 42 is also made of metal, and is electrically insulated from the outer cylinder 41 as the other electrode for measuring the liquid level. And are electrically connected. The outer peripheral surface 42G of the inner cylinder 42 is covered with an insulating coating 43 made of, for example, fluorine resin such as PTFE, PFA, ETFE, epoxy resin, polyimide resin, or the like. Even if the urea aqueous solution NL (liquid to be measured) is interposed in the outer cylinder 41, the outer cylinder 41 is electrically insulated.

In order to detect the liquid level NLH of the urea aqueous solution NL by the liquid level sensor unit 4, the liquid level sensor unit 4 is immersed in the urea aqueous solution NL, and the urea aqueous solution NL is connected to the outer cylinder 41 through the slit 41S. It flows between the inner cylinder 42 (insulating coating 43).
Then, in this liquid level sensor unit 4, between the outer cylinder 41 and the inner cylinder 42, a portion where the urea aqueous solution NL is present and a portion where the urea aqueous solution NL is present are formed according to the liquid level NLH. The capacitance of the capacitor formed between the cylinder 42 changes according to the liquid level NLH. Therefore, when an AC voltage is applied between the outer cylinder 41 and the inner cylinder 42, a current corresponding to the magnitude of this capacitance flows. Therefore, by knowing the magnitude of the current, the liquid level NLH of the urea aqueous solution NL is changed. Detect.

Next, the liquid concentration sensor unit 5 will be described.
The liquid concentration sensor unit 5 is disposed on the distal end side (downward in FIG. 1) of the liquid level sensor unit 4, and is composed of a concentration sensor element 51, a holder member 55, a protector 58, a rubber bush 56, and the like (FIG. 2 to FIG. 4).
Among these, the density sensor element 51 (see FIG. 6) is held by the holder member 55 in a form in which the tip portion thereof protrudes. The concentration sensor element 51 is electrically connected to a control circuit formed on the wiring board 22 via a connection terminal 52 and a connection cable 53 that are fixed to the density sensor element 51 by soldering. On the other hand, the holder member 55 is fixedly held on the distal end portion 411 of the outer cylinder 41 by a rubber bush 56 interposed between the holder member 55 and the outer cylinder 41 surrounding the holder member 55. Further, the protector 58 is engaged with and held by the distal end portion (small diameter portion 553) of the holder member 55 so as to surround the distal end portion 511 protruding from the holder member 55 of the density sensor element 51.

  First, the concentration sensor element 51 (see FIG. 6) in the liquid concentration sensor unit 5 will be described. This concentration sensor element 51 has a rectangular plate shape in plan view, and has two plate-like ceramic layers 519 (519A, 519B) made of alumina ceramics, and an internal liquid-tightly disposed therebetween. Wiring 516 is provided. The internal wiring 516 includes a pair of wide internal lead wirings 517 and an internal heater wiring 518 disposed between them and folded in a bellows shape.

Further, the concentration sensor element 51 includes a distal end portion 511 protruding from the holder member 55, an insertion portion 512 inserted into the holder member 55 adjacent to the proximal end side (upward in FIG. 6A) of the distal end portion 511, Furthermore, the resin holding part 513 located on the base end side of the insertion part 512 and the pair of connection terminals 52 are divided into base end parts 514 formed by soldering. An internal heater wiring 518 is disposed inside the distal end portion 511. Therefore, in the first embodiment, the tip portion 511 includes a temperature rise detection unit 510 that raises the temperature by energization.
The tip 511 has a main surface 511A composed of the ceramic layer 519A and a back surface 511B composed of the ceramic layer 519B in parallel with the main surface 511A. Further, regarding the temperature increase detection unit 510, the temperature increase detection unit 510 includes a temperature increase unit main surface 511AS included in the main surface 511A and a temperature increase unit back surface 511BS included in the back surface 511B.

  By the way, among the ceramic layers 519, one ceramic layer 519A is thinner than the other ceramic layer 519B. For this reason, the heat generated by the temperature rise detection unit 510 by the energization, specifically, the internal heater wiring 518 is more easily transferred to the ceramic 519A side than the ceramic layer 519B, and the external temperature Also, it is easy to be transmitted from the relatively thin ceramic layer 519A to the internal heater wiring 518.

  The connection terminal 52 is formed by bending a metal plate having a predetermined shape into a U shape. Among the connection terminals 52, the distal end portion 521 has a shape extending toward the distal end side (downward in FIG. 6), and is soldered to a pad (not shown) formed at the proximal end portion 514 of the concentration sensor element 51. The density sensor element 51 is fixedly connected by attaching. Thus, the connection terminal 52 (tip portion 521) is connected to the internal lead wiring 517 via a via conductor (not shown) that penetrates the one ceramic layer 519A. Therefore, when a voltage is applied between the pair of connection terminals 52, the internal heater wiring 518 mainly generates heat through the internal lead wiring 517. The resistance value of the internal heater wiring 518 changes according to its own temperature.

  On the other hand, the core wire 533 of the lead wire 532 of the connection cable 53 is electrically and mechanically connected to the base end portion 522 of the connection terminal 52 by soldering. As shown in FIGS. 1, 3, and 4, the connection cable 53 is inserted into the inner cylinder 42 and extends to the proximal end side, and is connected to the wiring board 22 (control circuit).

Next, the holder member 55 (see FIG. 8) will be described. The holder member 55 is entirely made of an insulating resin material. The outer shape of the holder member 55 is a large-diameter portion 551 having a relatively large cylindrical shape, a small-diameter portion 553 having a cylindrical shape smaller than the large-diameter portion 551, and the large-diameter portion 551 and the small-diameter portion. An intermediate taper portion 552 that is positioned between 553 and the outer peripheral surface is a tapered surface (conical frustum surface), and is positioned on the tip side (downward in FIG. 8A) from the small diameter portion, and the outer peripheral surface 554T is tapered. A tip tapered portion 554 that is a surface (conical frustum surface).
Moreover, this holder member 55 is a hollow member which has the holder through-hole 55H which penetrates self in an axial direction, as shown in FIG.8 (c). The holder through hole 55H is a three-stage circular hole portion of the inner cylinder holding hole 55H1, the second step hole 55H2, and the third step hole 55H3, which gradually becomes smaller in diameter from the base end side (upward in the drawing). And a substantially square hole-shaped element holding hole 55H4 located on the most distal side (downward in the figure).

As shown in FIGS. 3 and 4, the holder member 55 holds the concentration sensor element 51. Specifically, the insertion portion 512 of the concentration sensor element 51 is inserted into the element holding hole 55H4 of the holder member 55, and the resin holding portion 513 of the concentration sensor element 51 arranged in the third step hole 55H3 is the third holding hole 55H4. It is fixed by a sealing resin 59 filled in the step hole 55H3. The gap between the concentration sensor element 51 and the holder member 55 is liquid-tightly sealed by the sealing resin 59.
As a result, in the concentration sensor element 51, the tip end portion 511 in which the internal heater wiring 518 is disposed protrudes from the element holding hole 55H4 of the holder member 55 to the tip end side (downward in FIG. 1). Be placed.

Further, as shown in FIG. 3, the holder member 55 holds the tip 421 of the inner cylinder 42 inside the inner cylinder holding hole 55H1 of the holder through hole 55H. The stepped inner cylinder contact surface 55D located between the two-step hole 55H2 contacts the tip 422 of the inner cylinder 42 to position the inner cylinder 42 and the holder member 55 in the axial direction.
Two O-ring insertion grooves 55G1 and 55G2 are recessed in the inner cylinder holding hole 55H1 of the holder through-hole 55H, and the holder member 55 and the inner cylinder 42 are formed by O-rings 571 and 572 disposed inside these. The space between (insulating coating 43) is sealed in a liquid-tight manner, and the inner cylinder 42 is held.
Furthermore, in the inner cylinder holding hole 55H1 of the holder through hole 55H, the inner cylinder proximity facing surfaces 55H1B and 55H1C located between the two O-ring insertion grooves 55G1 and 55G2 and on the front end side of the O-ring insertion groove 55G2 Compared to the inner diameter, the inner cylinder separation facing surface 55H1A located on the base end side (higher side, upper in the drawing) than the O-ring insertion groove 55G1 is increased, and the inner cylinder 42 (insulating coating 43) The gap is increased. Further, a liquid introduction taper surface 55H1T having a diameter increasing toward the base end side is formed on the base end side (the upper side in the drawing) of the inner cylinder separation facing surface 55H1A. For this reason, when the urea aqueous solution NL is caused to flow between the outer cylinder 41 and the inner cylinder 42, the urea aqueous solution is surely provided between the inner cylinder separation facing surface 55H1A and the inner cylinder 42 (insulating resin 43). NL can be introduced. Accordingly, even though the liquid level is the same NLH, the outer cylinder 41 and the inner cylinder 42 are not held between the inner cylinder separation facing surface 55H1A and the inner cylinder 42 (insulating resin 43). The problem that an error occurs in the magnitude of the capacitance generated between the two can be solved.

  Further, since the holder member 55 holding the concentration sensor element 51 and the inner cylinder 42 are connected as described above, most of the proximal end portion 514 of the concentration sensor element 51 and the entire connection terminal 52 are connected. Is disposed in the inner cylinder 42. The concentration sensor element 51 and the connection terminal 52 are elastically formed in the inner cylinder 42 while insulating the density sensor element 51 and the connection terminal 52 and the inner cylinder 42 in the tip portion 421 of the inner cylinder 42. A separator 54 to be held is disposed.

The separator 54 is a member made of an insulating resin having rubber-like elasticity and having an outer shape and a substantially cylindrical shape. The separator 54 has two through holes 54H1 and 54H2 that extend in the axial direction and parallel to each other and pass through the separator 54, and a wall-shaped terminal that separates the two through holes 54H1 and 54H2. An inter-insulating portion 548 is provided. As shown in FIG. 4, the two through holes 54H1 and 54H2 are through holes for inserting and holding the connection terminal 52 and the lead wire 532, respectively.
In addition, the tip side portions of the two through holes 54H1 and 54H2 are configured to communicate with each other through a hole communication portion 54H3. Of the hole communication portion 54H3 and the through holes 54H1 and 54H2, the hole communication portion The base end portion 514 of the density sensor element 51 is inserted into a portion communicating with each other by 54H3. Therefore, the concentration sensor element 51 is brought into contact with the element contact portion 549 on the most distal side of the inter-terminal insulating portion 548 that separates the two through-holes 54H1 and 54H2. The axial positioning with respect to the separator 54 of 51 can be performed.

  Furthermore, a substantially ring-shaped contact protrusion 547 is formed in a plurality of steps (five steps in the first embodiment) at the tip portion of the outer peripheral surface 541G of the separator 54 (through hole wall portion 541). By inserting the separator 54 into the inner cylinder 42, the contact protrusion 547 contacts the inner peripheral surface 42 </ b> I of the inner cylinder 42, whereby the through-hole wall portion 541 is deformed radially inward, and the concentration sensor element 51 is elastically held by a separator 54. Thereby, even if the liquid state detection sensor 1 is mounted on an automobile or the like and is subjected to vibration or impact, the vibration or impact is prevented from being transmitted to the concentration sensor element 51.

In the first embodiment, the through hole wall portion 541 of the separator 54 is interposed between the inner cylinder 42 and the connection terminal 52 (see FIGS. 3 and 4). Specifically, in the separator 54 (through hole wall portion 541), a terminal-inner cylinder insulating portion 542 located at the central portion in the axial direction is interposed between the inner cylinder 42 and the connection terminal 52. This reliably prevents the connection terminal 52 from contacting the inner cylinder 42 and causing a short circuit. Further, the inter-terminal insulating portion 548 of the separator 54 is interposed between the pair of connection terminals 52. This reliably prevents the connection terminals 52 from coming into contact with each other and causing a short circuit.
Furthermore, since the connection terminal 52 is also elastically held, the connection terminal 52 is suppressed from vibrating even if vibration or impact is applied. In addition, in a connection portion by soldering or the like between the connection terminal 52 and the lead wire 532, a connection portion between the connection terminal 52 and the concentration sensor element 51, or in the vicinity of the connection portion of the connection terminal 52 or the concentration sensor element 51. It is possible to appropriately prevent the occurrence of defects such as cracks.

  Further, the inner cylinder engaging portion 546 located on the most distal end side of the separator 54 protrudes radially outward (in the left and right directions in FIGS. 3 and 4) and engages with the distal end 422 of the inner cylinder 42. The insertion depth of the separator 54 with respect to the inner cylinder 42 is regulated.

Next, the protector 58 in the liquid concentration sensor unit 5 will be described.
As shown in FIGS. 3 to 5 and 7, the protector 58 closes the cylindrical side portion 581 and the distal end side of the side portion 581 to surround the distal end portion 511 of the concentration sensor element 51 from below. It has a bottomed cylindrical shape including a bottom portion 582. As shown in FIGS. 3, 4, and the like, the side portion 581 of the protector 58 has the tip portion 511 when the protruding direction of the tip portion 511 of the density sensor element 51 is the gravity direction G, that is, downward. Is surrounded by an interval around the horizontal direction H. Further, in order to allow the urea aqueous solution NL to flow inside and outside of the protector 58, the side portion 581 extends from the three circular liquid flow holes 58H1, 58H2, 58H3, and the circular hole portion 58H41 to the front end side. Keyhole-shaped liquid circulation holes 58H4 each having a long slit portion 58H42 are uniformly formed in the circumferential direction.

In addition, three circular lower circulation holes 58H6, 58H7, and 58H8 are also formed in the bottom portion 582 so that the urea aqueous solution NL can flow inside and outside the protector 58. The lower flow holes 58H6, 58H7, 58H8 have a diameter smaller than that of the liquid flow hole 58H1 described above. That is, the diameters of the liquid circulation holes 58H1 to 58H3 and the circular hole part 58H41 are made larger than the diameters of the lower circulation hole 58H6 and the like formed in the bottom part 582.
Since the bubbles generated in the liquid generally move upward, it is considered that most of the bubbles entering the protector 58 (in an enclosed area EH described later) enter through the lower flow holes 58H6 to 58H8 of the bottom 582. It is done. On the other hand, it is desired to appropriately discharge the bubbles that have entered the protector 58 and moved further upward from the liquid circulation holes 58H1 to 58H4 to the outside of the protector 58 (enclosed region EH). Thus, in the first embodiment, the size of the lower flow hole 58H6 and the like is made relatively smaller than the liquid flow hole 58H1 and the like, thereby limiting the size of bubbles that enter the protector 58 (enclosed region EH). ing. On the other hand, by making the size of the liquid circulation hole 58H1, etc. larger than that of the lower circulation hole 58H6, the bubbles that have entered through the lower circulation hole 58H6 can be appropriately discharged from the liquid circulation hole 58H1, etc. .

In addition, of the side portions 581 of the protector 58, four locking tongues 583 are formed in the vicinity of the proximal end (near the upper end in the figure) and formed inwardly by folding a U-shaped cut, and are equally distributed around the circumferential direction. Is formed.
As a result, as shown in FIG. 9, the locking tongue portion 583 of the protector 58 is locked to the protector locking recess 55 </ b> G <b> 3 formed on the outer periphery of the small diameter portion 553 of the holder member 55. Accordingly, the protector 58 is disposed so as to surround the small diameter portion 553 and the tip tapered portion 554 of the holder member 55 and the tip portion 511 of the concentration sensor element 51, and includes the surrounding region EH therein. become. Accordingly, in the holder member 55, the tapered outer peripheral surface 554T forming the outer surface of the tip tapered portion 554 and the flat tip surface 554S facing the tip side face the surrounding region EH (see FIG. 5).

At this time, as shown in FIG. 5, in the protector 58, all of the liquid flow holes 58H1 to 58H4 are formed on the main surface 511A and the back surface 511B of the tip portion 511 of the concentration sensor element 51, and more specifically, It is engaged with the holder member 55 so as to be disposed at a position that does not face the temperature raising portion main surface 511AS and the temperature raising portion back surface 511BS.
Here, if liquid flows in various directions occur in the urea aqueous solution NL, any one of the liquid circulation holes 58H1 to 58H4 of the protector 58 is the main temperature rising portion of the tip portion 511 of the concentration sensor element 51. When facing the surface 511AS and the temperature raising portion back surface 511BS, the liquid flow that has entered from the liquid flow hole 58H1 or the like facing the surface 511AS is the temperature rising portion main surface 511AS or the temperature raising portion back surface 511BS of the temperature rising detection portion 510. The liquid flow is likely to cause a large influence such as the temperature rise of the temperature rise detection unit 510 being hindered by the liquid flow.
On the other hand, in the first embodiment, as described above, the liquid circulation holes 58H1 and the like of the protector 58 are arranged at positions that do not face the temperature riser main surface 511AS and the temperature riser rear surface 511BS of the temperature rise detection unit 510. Do it. Specifically, the temperature rising portion main surface 511AS or the temperature rising portion back surface 511BS of the temperature rising detection portion 510 is outside the virtual temperature rising portion main surface projection region or the temperature rising portion back surface projection region projected in the thickness direction. Each flow hole is arranged. For this reason, since the generation of a liquid flow that travels so as to collide with the main surface of the temperature rising portion or the back surface of the temperature rising portion of the temperature rising detection portion 510 is prevented, the temperature increase of the temperature rising detection portion 510 is caused by such a liquid flow. The influence such as obstruction can be reduced, and the concentration of the specific component of the liquid can be detected more accurately.

Further, in this way, the holder member 55 holding the concentration sensor element 51 and the protector 58 is held by an insulating rubber bush 56 having a holder holding hole 56H adapted to the outer peripheral surface thereof.
As shown in FIGS. 2 to 4, the rubber bush 56 is formed with a cylindrical bush main body 561 having the above-mentioned holder holding hole 56 </ b> H formed at the center thereof and having an outer diameter that can be fitted to the outer cylinder 41. The bush body 561 has locking projections 562 that are equally disposed at three locations on the outer periphery of the bush body 561 and project radially outward from the bush body 561. The holder holding hole 56 </ b> H of the bush main body 561 is in close contact with the holder member 55 and the protector 58 and has a shape capable of holding them.

  The rubber bush 56 is held by the outer cylinder 41 by inserting and locking the locking projections 562 into the holding holes 41H of the outer cylinder 41. Thus, the holder member 55 that holds the concentration sensor element 51 and the protector 58 is held by the rubber bushing 56, and the rubber bushing 56 is held by the outer cylinder 41, so that the entire liquid concentration sensor unit 5 is attached to the outer cylinder 41. It is held between the tip 411 and the tip 421 of the inner cylinder 42.

  Further, a number of outer peripheral slits 561G extending in the axial direction (vertical direction in FIG. 2) are formed in the outer peripheral surface of the bush main body 561 between the locking projections 562. As shown in FIGS. 3 and 4, the outer circumferential slit 561G is fitted between the bush body 561 and the outer cylinder 41 in the axial direction (up and down in the figure) by fitting the rubber bush 56 into the outer cylinder 41. Direction) of the urea aqueous solution NL, and a flow passage that allows bubbles to be removed.

Further, a positioning member 60 shown in FIG. 10 is fitted into the distal end portion 411 of the outer cylinder 41 on the distal end side (downward in the drawing) from the rubber bush 56. The positioning member 60 includes a positioning plate portion 601 having an outer diameter substantially equal to the inner diameter of the outer cylinder 41, a flat plate ring shape having an insertion hole 601H at the center, and a direction perpendicular to the periphery of the positioning plate portion 601. And three leg portions 602 extending in the direction. The ends of the leg portions 602 are bent outward in the radial direction to form engagement claw portions 602K.
In the sensor 1 of the first embodiment, as shown in FIGS. 3 and 4, the leg portion 602 of the positioning member 60 is engaged with the engaging claw portion 602 </ b> K in a state where the positioning plate portion 601 is inserted into the outer cylinder 41. Is engaged with the tip 41T of the outer cylinder 41 and welded. On the other hand, the positioning plate portion 601 is in a state in which the protector 58 and the tip end portion 511 of the density sensor element 51 are inserted into the insertion hole 601H and in contact with the flat tip end side surface 56S located at the tip end of the rubber bush 56. . Since the dimension of the leg portion 602 in the axial direction (vertical direction in the drawing) is determined in advance, the positioning of the rubber bush 56 in the axial direction can be accurately performed.

Further, a rectifying member 61 shown in FIG. 11 is fitted into the distal end portion 411 of the outer cylinder 41 on the distal end side of the positioning member 60. The rectifying member 61 extends from the disc-shaped rectifying plate portion 611 having an outer diameter smaller than the inner diameter of the outer cylinder 41 and the peripheral edge of the rectifying plate portion 611 to the oblique base end side (upward) in the drawing. And three leg portions 612 having a substantially V shape extending toward the tip side (downward). The front ends of the leg portions 612 are bent outward in the radial direction to form engagement claw portions 612K.
In the sensor 1 of the first embodiment, as shown in FIGS. 3 and 4, the leg portion 612 of the rectifying member 61 is further in the state where the positioning plate portion 601 is inserted and fixed in the outer cylinder 41. The engaging claw portion 612K is engaged with the tip 41T of the outer cylinder 41 and welded. Note that the engaging claw portion 602K of the positioning member 60 and the engaging claw portion 612K of the rectifying member 61 are welded at positions shifted by 60 degrees around the axis AX.

  Thereby, the baffle plate part 611 of the baffle member 61 will be in the state which block | closes part (center part) opening of the front-end | tip part 411 of the outer cylinder 41. FIG. Specifically, when the sensor 1 (outer cylinder 41) is viewed from the front end side in the axial direction (downward in FIGS. 3 and 4), the bottom portion 582 of the protector 58 is moved by the rectifying plate portion 611 of the rectifying member 61. It is supposed to be invisible. In this way, when the urea aqueous solution NL stored in the tank (not shown) is moved by vibration and a violent liquid flow is generated in the tank, the sensor 1 located above the upper cylinder 41 from the lower side is particularly provided. Even when a liquid flow toward the concentration sensor element 51 occurs, the rectifying plate portion 611 prevents the liquid flow from proceeding. Therefore, such a liquid flow enters the protector 58 (in the enclosed area EH) through holes such as the lower flow hole 58H6 provided in the bottom 582 of the protector 58, and a liquid flow that strongly strikes the concentration sensor element 51 is generated. Thus, the problem that the output of the concentration sensor element 51 fluctuates can be appropriately suppressed.

Furthermore, in the sensor 1 of the first embodiment, as shown in FIGS. 3, 4, and 5, the liquid flow holes 58 </ b> H <b> 1 to 58 </ b> H <b> 4 provided in the side portion 581 of the protector 58 and the concentration sensor element 51 are held. The tip taper portion 554 of the holder member 55 has the following relationship.
That is, the distal end taper portion 554 includes a flat distal end surface 554S orthogonal to the axis AX and a tapered outer peripheral surface 554T whose diameter increases toward the base end side (upward in the drawing). In addition, the base end 58 </ b> H <b> 1 </ b> K, 58 </ b> H <b> 2 </ b> K, 58 </ b> H <b> 3 </ b> K, 58 </ b> H <b> 4 </ b> K is positioned higher than the base end side end 554 </ b> K of the outer peripheral surface 554 </ b> T. Thus, each liquid circulation hole 58H1-58H4 is arrange | positioned. In addition, the tip end 58H1S, 58H2S, 58H3S, 58H4S located at the lowest position among the peripheral edges of the liquid circulation holes 58H1 to 58H4 is positioned at a lower position than the base edge 554K of the outer peripheral surface 554T. Each liquid circulation hole 58H1-58H4 is arrange | positioned.

  With this configuration, even when a bubble enters the surrounding area EH, the bubble rises along the tapered outer peripheral surface 554T without staying around the tip portion 511 of the concentration sensor element 51. And move radially outward. Further, the bubbles that have moved to the outside in the radial direction are unlikely to return to the periphery of the distal end portion 511 on the inside in the radial direction. Further, each of the liquid circulation holes 58H1 to 58H4 has a proximal end (upper end) 58H1K and the like higher than the proximal end edge 554K, and a distal end (lower end) 58H1S and the like from the proximal end edge 554K. Therefore, the bubbles in the vicinity of the proximal end edge 554K are easily discharged out of the protector 58 through the liquid circulation holes 58H1 to 58H4.

Specifically, in the holder member 55, any part of the front end surface 554 </ b> S and the outer peripheral surface 554 </ b> T facing the surrounding area EH surrounded by the protector 58 is the hole peripheral edge 55 </ b> H <b> 4 </ b> F of the element holding hole 55 </ b> H <b> 4 of the holder member 55. It is configured to be located at the same level or higher than (the lowest hole periphery). Also, each of the liquid circulation holes 58H1 to 58H4 has its own base end (upper end) 58H1K to 58H4K higher than the hole peripheral edge 55H4F of the element holding hole 55H4. Further, the distal end (lower end) 58H1S to 58H4S is lower than the proximal end edge (surface peripheral edge) 554K of the outer peripheral surface 554T of the distal tapered portion 554.
For this reason, bubbles that have entered the surrounding area EH can be discharged from the liquid circulation holes 58H1 and the like positioned higher than the periphery of the concentration sensor element 51. In other words, each of the liquid circulation holes 58H1 to 58H4 is not only a liquid circulation, but also a bubble discharge circulation hole that appropriately discharges the bubbles that have entered the surrounding area EH.
In the first embodiment, since the tip end surface 554S of the holder member 55 is a flat surface orthogonal to the axis AX, all the portions of the hole peripheral edge 55H4F of the element holding hole 55H4 have the same height. Therefore, any part of the hole periphery 55H4F is the lowest hole periphery of the hole periphery 55H4F.

Further, in the holder member 55, the front end surface 554S is a flat surface having the same height, and the outer peripheral surface 554T is a tapered surface positioned higher than this. In other words, when comparing the respective portions of the distal end surface 554S and the outer peripheral surface 554T facing the surrounding region EH, the portion closer to the proximal end edge (surface peripheral edge) 554K is higher or the same height. It is made into the form which is located in. Specifically, the distal end surface 554S is positioned at the same height as the hole peripheral edge 55H4F of the element holding hole 55H4 even when approaching the proximal end edge (surface peripheral edge) 554K. Further, in the outer peripheral surface 554T, the portion closer to the base end side edge (surface periphery) 554K is higher.
Moreover, as described above, the liquid flow hole (bubble discharge flow hole) 58H1 and the like have their base end side end (upper end) 58H1K and the like higher than the base end side end edge (surface peripheral edge) 554K of the outer peripheral surface 554T. The distal end (lower end) 581HS and the like are lower than the proximal end edge (surface periphery) 554K of the outer peripheral surface 554T.
Since the front end surface 554S and the outer peripheral surface 554T of the holder member 55 are configured in this way, the bubbles that have reached the front end surface 554S or the outer peripheral surface 554T are moved radially outward along these surfaces, and the protector is removed from the liquid circulation hole 58H1 and the like. 58 can be easily discharged to the outside.

Furthermore, the holder member 55 has a surrounding region surface (a distal end surface 554S and an outer peripheral surface 554T) as well as a distal end surface 554S around the element holding hole 55H4, and a surface peripheral side (base end side edge side) of the surrounding region surface. The outer peripheral surface 554T is located higher than the front end surface 554S, including the base end side surface periphery 554K which is the surface periphery of the surrounding area surface.
By doing so, the outer peripheral surface 554T is positioned higher than the front end surface 554S and forms a “float”, so that once the bubbles move to the outer peripheral surface 554T side, it is difficult to return to the front end surface 554S side. Therefore, the air bubbles that have entered the surrounding area EH can be reliably moved toward the proximal side rim 554K. In addition, even in the relationship with the bubble discharge / circulation hole (liquid circulation hole) 58H1 and the like, the bubbles can be discharged more appropriately because of the above.
In addition, the front end surface 554S and the outer peripheral surface 554T in Embodiment 1 correspond to the surrounding region surface in the present invention. Further, the front end surface 554S corresponds to the element peripheral surface, and the outer peripheral surface 554T corresponds to the peripheral side surface.

  Next, in the sensor 1 of the first embodiment, the liquid flow holes 58H1 to 58H4 of the protector 58, the flow hole 41R of the outer cylinder 41, the front end side surface 56S of the rubber bush 56, and the front end side surface of the positioning plate portion 601 of the positioning member 60. The relationship with 601S will be described with reference to FIG. 12 (see also FIGS. 3, 2, and 10). The liquid flow holes 58H1 to 58H4 of the protector 58 correspond to the flow holes and bubble discharge flow holes of the surrounding member. Further, the flow hole 41R of the outer cylinder 41 corresponds to the outer flow hole and the bubble discharge outer flow hole of the outer surrounding member. Furthermore, the front end side surface 56S of the rubber bush 56 and the front end side surface 601S of the positioning plate portion 601 of the positioning member 60 correspond to the lower surface of the interposed member of the interposed member. The flow hole 41R not only allows the aqueous urea solution NL to flow, but as can be seen from FIG. 12, its own base end 41RK (upper end) is a liquid flow hole 58H1 to 58H4 (bubble discharge flow hole). Higher than the base end 58H1K to 58H4K (upper end).

The tip portion 411 of the cylindrical outer cylinder 41 surrounds the periphery of the tip portion 511 of the density sensor element 51 in the horizontal direction H and the periphery of the protector 58 in the horizontal direction H with a gap from the protector 58. . Therefore, an outer surrounding region FH is formed between the tip 411 of the outer cylinder 41 and the protector 58.
As already described, the front end 411 of the outer cylinder 41 has a flow hole 41R through which the urea aqueous solution NL can flow between the outer surrounding region FH and the outside in the horizontal direction H of the front end 411 of the outer cylinder 41. Three holes are formed at equal intervals in the circumferential direction. These three circulation holes 41R are all the same shape and are arranged at the same position in the axis AX direction (gravity direction G).

  Further, a rubber bush 56 and a positioning member 60 are interposed between the protector 58 and the tip 411 of the outer cylinder 41. The rubber bushing 56 and the positioning plate portion 601 of the positioning member 60 are located on the base end side (upward in the drawing) of the outer surrounding region FH, and the distal end side surface 56S and the distal end side surface 601S face the outer surrounding region FH. is doing. In other words, the rubber bush 56 and the positioning plate portion 601 of the positioning member 60 corresponding to the interposition member constitute the interposition member lower surface KS indicated by a broken line in FIG. 12 by the front end side surface 56S and the front end side surface 601S. Yes.

In the first embodiment, the interposed member lower surface KS has an annular shape between the protector 58 and the distal end portion 411 of the outer cylinder 41, and the distal end side surface 601S occupies most of the entire surface. I am doing. Therefore, in the interposition member lower surface KS, an annular portion located on the protector 58 side (inner side) is referred to as an inner peripheral edge KSI, and an annular portion located on the outer cylinder 41 side (outer side) is referred to as an outer peripheral edge KSO. To do.
Further, a portion of the inner peripheral edge KSI located outside the liquid circulation holes 58H1 to 58H4 (in FIG. 12, the liquid circulation holes 58H3) of the protector 58 in the horizontal direction H (left and right direction in the drawing) The corresponding part KSIC is used. Moreover, the site | part located in the horizontal direction H (left-right direction in the figure) inner side of the circulation hole 41R of the outer cylinder 41 among the outer periphery edge part KSO is made into the discharge hole corresponding | compatible part KSOC.

  Then, in this Embodiment 1, each discharge hole corresponding | compatible part KSIC is made higher than the upper ends 58H1K-58H4K of the corresponding liquid circulation holes 58H1-58H4 among the inner peripheral edge KSI of the interposed member lower surface KS. You can see that As described above, the bubbles that have entered the surrounding area EH (inside the protector 58) do not stay around the tip portion 511 of the concentration sensor element 51, and are along the outer peripheral surface 554T of the tip taper portion 554 of the holder member 55. And then move radially outward. And the bubble which moved to the radial direction outer side is discharged | emitted out of the protector 58 through each liquid circulation hole 58H1-58H4. At this time, as described above, each of the discharge hole corresponding parts KSIC is higher than the upper ends 58H1K to 58H4K of the corresponding liquid circulation holes 58H1 to 58H4. Can do.

  In the first embodiment, among the outer peripheral edge portions KSO of the interposed member lower surface KS, each of the outer discharge hole corresponding portions KSIO is higher than the front end side end 41RS (lower end) of the corresponding flow hole 41R. You can see that Therefore, when a bubble is located in the vicinity of the outer discharge hole corresponding part KSIO, it can be discharged out of the outer cylinder 41 through each flow hole 41R.

Moreover, the interposition member lower surface KS is substantially horizontal as described above. Therefore, when the bubbles (bubble groups) that have entered the surrounding area EH are discharged from the liquid circulation holes 58H1 to 58H4, the bubbles (bubble groups) are formed along the interposed member lower surface KS in the upper part of the outer surrounding area FH. Move to expand. Thereby, a part of the bubble group moves from the discharge hole corresponding part KSIC to the outer discharge hole corresponding part KSOC along the interposed member lower surface KS.
Thus, the bubbles (bubble groups) discharged from the liquid circulation holes 58H1 to 58H4 can be discharged out of the outer cylinder 41 through the respective circulation holes 41R.

  In addition, when there is little liquid flow and vibration, a bubble moves along the interposed member lower surface KS from the discharge hole corresponding part KSIC to the outer discharge hole corresponding part KSOC. As is clear from FIG. 12, the interposition member lower surface KS is higher than the proximal end 58H1K to 58H4K (upper end) of the liquid circulation holes 58H1 to 58H4 corresponding to the discharge hole corresponding part KSIC. is there. Therefore, the bubbles (bubbles) once discharged from the liquid circulation holes 58H1 to 58H4 to the outer surrounding area FH are prevented from flowing back into the surrounding area EH (inside the protector 58) through the liquid circulation holes 58H1 to 58H4. ing.

Next, the operation of the liquid concentration sensor unit 5 of the sensor 1 will be described in detecting the concentration of the urea aqueous solution NL.
In the liquid state detection sensor 1 according to the first embodiment, a current having a predetermined magnitude is supplied from the control circuit configured on the wiring substrate 22 to the concentration sensor element 51 of the liquid concentration sensor unit 5 for a predetermined time (for example, 700 ms). The internal heater wiring 518 generates heat. Then, a detection voltage corresponding to the magnitude of its own resistance value is generated in the internal heater wiring 518. Therefore, the change in the detection voltage is detected by the control circuit to detect the concentration of the urea aqueous solution NL. Specifically, the detection voltage immediately after the start of energization of the concentration sensor element 51 and the detection voltage after the elapse of a predetermined time from the start of energization are measured. Then, using the amount of change in the detected voltage during this period, the concentration of the urea aqueous solution NL corresponding to this amount of change is obtained from the relationship between the concentration of the urea aqueous solution NL and the amount of change obtained in advance.
In the first embodiment, the concentration of the urea aqueous solution NL is detected by using a CPU or the like in the control circuit, and the concentration information signal obtained by the control circuit is transmitted through the external connection cable 24 to the external circuit. (For example, ECU). This external circuit determines whether or not the concentration of the urea aqueous solution NL is within an appropriate range based on the input concentration information signal. If the concentration is not within the appropriate concentration range, the driver is notified accordingly. Processing such as performing is performed as appropriate.

(Deformation)
Next, a modification of the first embodiment will be described with reference to FIG.
The sensor 1001 according to this modified embodiment is different from the first embodiment described above only in the shape of the tip portion of the holder member, and only the different portions will be described. Further, only parts different from those of the first embodiment are given different numbers.
In the first embodiment described above, the holder member 55 has a flat distal end surface 554S perpendicular to the axis AX and a tapered outer peripheral surface 554T located around this and having a diameter increasing toward the proximal end. It had the front-end | tip taper part 554 which has.

On the other hand, as shown in FIG. 13, the holder member 155 according to the sensor 1001 of the present modified embodiment does not have a flat front end surface, and from the hole periphery 155H4F of the element holding hole 155H4, It has a tapered outer peripheral surface 1554T whose diameter increases toward the base end side. That is, the distal end taper portion 1554 surrounded by the protector 58 has an outer peripheral surface 1554T (enclosed region surface) facing the surrounding region EH from the hole peripheral edge 155H4F of the element holding hole 155H4 to the base end side edge (surface peripheral edge). It becomes a form which becomes higher as it approaches.
In other words, with respect to the outer peripheral surface 1554T (enclosed region surface), a portion that gradually becomes higher when viewed along the path from the hole peripheral edge 155H4F of the element holding hole 155H4 to the proximal end edge (surface peripheral edge) of the outer peripheral surface 1554T, Or it is set as the form where either of the site | parts which become high level in a step shape appears.

  Therefore, in the sensor 1001, once the bubble moves to the base end side edge (surface peripheral edge) 1554K side of the outer peripheral surface 1554T, it is difficult to return to the element holding hole 155H4 side. Therefore, the air bubbles that have entered the surrounding area EH are moved more smoothly along the outer peripheral surface 1554T toward the base end side edge (surface peripheral edge) 1554K, and are moved out of the protector 58 through the liquid circulation holes 58H1 to 58H4. Can be discharged. In this way, it is possible to further suppress the influence of bubbles in density detection by the density sensor element 51 due to bubbles.

Also in this modified embodiment, the relationship between the holder member 155 and the liquid circulation holes 58H1 to 58H4 is the same as that in the above-described embodiment. That is, any part of the outer peripheral surface (enclosed region surface) 1554T of the holder member 155 is positioned higher than the hole peripheral edge (lowest hole peripheral edge) 155H4F of the element holding hole 155H4.
The liquid flow hole 58H1 and the like have a base end (upper end) 58H1K and the like higher than the hole peripheral edge 55H4F, and a tip end (lower end) 58H1S and the like are the base of the outer peripheral surface (enclosed area surface) 1554T. It is lower than the end side edge (surface periphery) 1554K.
Further, the liquid flow hole 58H1 and the like have a base end (upper end) 58H1K and the like that are higher than the base end side edge (surface periphery) 1554K of the outer peripheral surface (enclosure region surface) 1554T, The end (lower end) 58H1S or the like is lower than the base end side edge (surface peripheral edge) of the outer peripheral surface (enclosed region surface).

  The relationship between the liquid flow holes 58H1 to 58H4 of the protector 58, the flow hole 41R of the outer cylinder 41, the front end side surface 54S of the rubber bush 56 and the front end side surface 601S of the positioning plate portion 601 of the positioning member 60 is also described above. The same as in the first embodiment. Accordingly, the same is true in that bubbles (bubble groups) discharged from the liquid circulation holes 58H1 to 58H4 can be discharged out of the outer cylinder 41 through the respective circulation holes 41R.

(Embodiment 2)
Next, a second embodiment of the present invention will be described with reference to FIGS. The liquid state detection sensor 2001 according to the second embodiment is different from the first embodiment described above in that the holder member, the rubber bush, the protector, the positioning member, and the rectifying member are only slightly different in shape. Description will be made mainly, and description of similar parts will be omitted or simplified.

The liquid state detection sensor 2001 (see FIG. 14) according to the second embodiment is also used in a device that detects the concentration of the aqueous urea solution NL stored in the storage tank and the liquid level NLH of the aqueous urea solution NL. Similarly to the first embodiment, the liquid state detection sensor 2001 includes a base portion 2 and a sensor portion 3 extending downward in the drawing, and the base portion 2 is attached around an opening of a storage tank (not shown). The sensor unit 3 is used by being immersed in the urea aqueous solution NL, with the sensor unit 3 extending in the gravity direction G.
Therefore, also in the description of the sensor 2001 and each component, in the direction along the axis AX shown in FIG. 14 (axial direction), the upper side is described as the base end side and the lower side is described as the front end side.
Further, when specifying or describing a part related to the posture of the sensor 2001 or the gravity direction G, the direction in which the sensor unit 3 extends with respect to the base 2 (of the direction along the axis AX shown in FIG. 14 (axis direction)). The orientation with the gravity direction G as the downward direction) will be described as a basis.

  Of the liquid state detection sensor 2001, the base 2 is the same as that of the first embodiment. On the other hand, the sensor unit 3 includes a liquid level sensor unit 4 similar to that of the first embodiment, and a liquid concentration sensor unit 2005 that is positioned on the distal end side and positioned on the lower side in use. Therefore, description of the base 2 and the liquid level sensor 4 is omitted.

  Next, the liquid concentration sensor unit 2005 will be described. Similar to the liquid concentration sensor unit 2005 in the first embodiment, the liquid concentration sensor unit 2005 is disposed on the leading end side (downward in FIG. 14) of the liquid level sensor unit 4. The liquid concentration sensor unit 2005 includes the same concentration sensor element 51 and separator 54 as in the first embodiment, a holder member 255, a protector 258, a rubber bushing 256, and the like that are slightly different from those in the first embodiment (FIG. 14). To FIG. 21).

  Further, as in the first embodiment, the concentration sensor element 51 (see FIG. 6) is held by the holder member 255 in a form in which the tip portion thereof protrudes. Further, the density sensor element 51 is electrically connected to a control circuit formed on the wiring board 22 via a connection terminal 52 and a connection cable 53 which are fixed by soldering. On the other hand, the holder member 255 is fixedly held on the distal end portion 411 of the outer cylinder 41 by a rubber bushing 256 interposed between the holder member 255 and the outer cylinder 41 surrounding the holder member 255. Further, the protector 258 is engaged with and held by the distal end portion (small diameter portion 2553) of the holder member 255 so as to surround the distal end portion 511 protruding from the holder member 255 in the density sensor element 51.

  In the liquid concentration sensor unit 2005, the concentration sensor element 51 (see FIG. 6) and the separator 54 are the same as those in the first embodiment, and a description thereof will be omitted. Further, the holder member 255 (see FIGS. 15 and 16) that holds the concentration sensor element 51 is also the same as that of the first embodiment except for the shape of the distal end portion (the outer peripheral surface 2554T of the distal end tapered portion 2554). Is omitted. The outer peripheral surface 2554T of the tip tapered portion 2554 of the holder member 255 is a tapered surface (conical frustum surface). However, the outer peripheral surface 554T in the first embodiment (see FIG. 12) has a gentler taper. The only difference is that

Next, the protector 258 will be described. As shown in FIGS. 15 and 16, the protector 258 has a bottomed cylindrical shape including a cylindrical side portion 2581 and a bottom portion 2582 that closes the distal end side of the side portion 2581. The side portion 2581 surrounds the periphery of the front end portion 511 in the horizontal direction H with a gap when the protruding direction of the front end portion 511 of the density sensor element 51 is the gravity direction G. Further, in this side portion 2581, in order to allow the urea aqueous solution NL to flow inside and outside of the protector 258, there are four circular upper liquid circulation holes 258H1, 258H1,..., And four circles positioned on the tip side. The lower liquid circulation holes 258H2, 258H2,... Have a uniform shape in the circumferential direction.
In addition, in the bottom portion 2582, one circular lower flow hole 258H6 is formed so that the urea aqueous solution NL can flow inside and outside the protector 258.

  In addition, in the same manner as in the first embodiment, among the side portions 2581 of the protector 258, there are four locking tongue portions 2583 that are bent inwardly at the proximal end (near the upper end in the figure), in the circumferential direction. It is evenly formed around. By engaging the locking tongue 2583 with the protector locking recess 55G3 of the holder member 55, the locking tongue 2583 of the protector 258 is locked. Accordingly, the protector 258 is disposed so as to surround the tip tapered portion 2554 of the holder member 255 and the tip portion 511 of the concentration sensor element 51, and the surrounding region EH is included therein. Therefore, in the holder member 255, the tapered outer peripheral surface 2554T of the tip tapered portion 2554 and the flat tip surface 2554S facing the tip side face the surrounding region EH.

In this way, the holder member 255 holding the concentration sensor element 51 and the protector 258 is held by an insulating rubber bushing 256 having a holder holding hole 256H adapted to the outer peripheral surface thereof.
As shown in FIGS. 18 and 19, the rubber bushing 256 has a cylindrical bush main body 2561 having the above-mentioned holder holding hole 256 </ b> H formed at the center thereof and having an outer diameter that can be fitted to the outer cylinder 41. The bushing body portion 2561 is provided with three locking projections 2562 that are evenly disposed at three locations on the outer periphery and project outward from the bushing body portion 2561 in the radial direction. The holder holding hole 256 </ b> H of the bush main body 2561 is in a shape that allows the holder member 255 and the protector 258 to be in close contact with each other and hold them.

The rubber bushing 256 is also held by the outer cylinder 41 by locking the locking projection 2562 in the holding hole 41H of the outer cylinder 41. Thus, the holder member 255 that holds the concentration sensor element 51 and the protector 258 is held by the rubber bushing 256, and the rubber bushing 256 is held by the outer cylinder 41, so that the entire liquid concentration sensor unit 2005 is attached to the outer cylinder 41. It is held between the tip 411 and the tip 421 of the inner cylinder 42.
As a result, an outer surrounding region FH is formed between the protector 258 and the distal end portion 411 of the outer cylinder 41.

  Further, as in the first embodiment, in the bush main body 2561, the outer peripheral surface between the locking projections 2562 is provided with a number of outer peripheral slits 2561G extending in the axial direction (vertical direction in FIG. 18). ing. As shown in FIG. 15, the outer peripheral slit 2561G allows the urea aqueous solution NL to flow and remove bubbles between the bush main body 2561 and the outer cylinder 41 in the axis AX direction (vertical direction in the figure). To form a flow passage.

  However, in the rubber bush 56 of the first embodiment, the front end side surface 56S is a flat surface orthogonal to the axis AX. On the other hand, the rubber bushing 256 according to the second embodiment has notches 2563 constituting the distal side oblique plane 256S2 at three locations in the circumferential direction in the distal end side portion of the bush main body 2561. For this reason, the front end side surface 256S includes a front end side oblique flat surface 256S2 in addition to a flat front end side flat end surface 256S1 orthogonal to the axis AX.

Further, the positioning member 260 and the rectifying member 261 shown in FIGS. 20 and 21 are fitted into the distal end portion 411 of the outer cylinder 41 on the distal end side (downward in the drawing) from the rubber bushing 256 as in the first embodiment. (See FIGS. 14 and 15). However, the positioning member 260 and the rectifying member 261 are different in shape from the positioning member 60 and the rectifying member 61 in the first embodiment.
That is, in the positioning member 60 of the first embodiment, the positioning plate portion 601 is a flat plate ring having an outer diameter substantially equal to the inner diameter of the outer cylinder 41, and has an insertion hole 601H at the center thereof. On the other hand, in the positioning member 260 of the second embodiment, the positioning plate portion 2601 has a flat plate shape, and the outer periphery of the flat plate ring whose outer diameter is substantially equal to the inner diameter of the outer cylinder 41 in the plan view is circumferentially arranged. By forming a cutout portion 2601C by linearly cutting it at three places, a substantially hexagonal shape in which arcs and straight lines appear alternately on the outer periphery is formed. In addition, an insertion hole 2601H is provided at the center thereof. Note that leg portions 2602 extend from a portion of the peripheral edge of the positioning plate portion 2601 that forms a circular arc at three locations in a direction perpendicular to the circular arc (axis AX direction). The ends of the leg portions 2602 are bent outward in the radial direction to form engagement claw portions 2602K.

  Further, a rectifying member 261 is fitted into the positioning member 260. The rectifying member 261 has a substantially disc-shaped rectifying plate portion 2611 (see FIG. 21) having an outer diameter smaller than the inner diameter of the outer cylinder 41 and having a bulging portion in three directions, and a peripheral edge of the rectifying plate portion 2611. In the figure, after extending obliquely to the base end side (upward), it is composed of three leg portions 2612 extending to the base end side (upward). The leg portions 2612 are respectively arranged on and along the leg portions 2602 of the positioning member 260, and the leg portions 2612 are abutted against the positioning plate portion 2601 of the positioning member 260 at the proximal end. . In this state, the leg portion 2612 of the rectifying member 261 is welded to the leg portion 2602 of the positioning member 260 (not shown), and the positioning along the axis line AX (the vertical direction in the figure) and the circumferential direction is performed. And are integrated with each other.

  In the sensor 2001 of the second embodiment, as shown in FIGS. 15 and 16, the positioning member 260 and the rectifying member 261 are almost entirely inserted into the outer cylinder 41. Then, the engaging claw portion 2602K of the leg portion 2602 of the positioning member 260 is engaged with the tip 41T of the outer cylinder 41, and positioning in the direction along the axis AX of the positioning member 260 and the rectifying member 261 is performed. The leg portion 2602 of the positioning member 260 is welded to the outer cylinder 41 (not shown).

Accordingly, the positioning plate portion 2601 inserts the protector 258 and the distal end portion 511 of the density sensor element 51 into the insertion hole 2601H, and comes into contact with the flat distal end side flat surface 256S1 positioned on the distal end side of the rubber bush 256. It is in a state. Thus, the rubber bushing 256 is also positioned in the direction along the axis AX.
The front end side flat surface 256S1 of the rubber bushing 256 and the positioning plate portion 2601 of the positioning member 260 are arranged such that the leg portion 2602 of the positioning member 260 is positioned on the front end side of the engaging protrusion 2562 of the rubber bush 256. Has been. For this reason, the presence of the notch portion 2601C in the positioning plate portion 2601 exposes the notch portion 2563 of the rubber bushing 256 without being covered by the positioning plate portion 2601 (see FIGS. 16 and 17). In addition to the front end side 2601S which is the lower surface of the positioning plate portion 2601 of the positioning member 260, a part of the front end side flat surface 256S1 of the front end side surface 256S of the rubber bush 256 and the front end side oblique plane 256S2 forming the notch 2563 are Facing the outer surrounding area FH.

  Further, as in the first embodiment, the rectifying plate portion 2611 of the rectifying member 261 is in a state of partially closing (opening the central portion) the opening of the distal end portion 411 of the outer cylinder 41. Thereby, the malfunction which the output of the density | concentration sensor element 51 fluctuates with the liquid flow which arose in the urea aqueous solution NL can be suppressed appropriately.

Further, as in the first embodiment, the sensor 2001 of the second embodiment also holds the liquid flow holes 258H1 and 258H2 provided in the side portion 2581 of the protector 258 and the concentration sensor element 51, as shown in FIGS. The tip taper portion 2554 of the holder member 255 is as follows.
As described above, the surface of the distal end taper portion 2554 is constituted by the flat distal end surface 2554S orthogonal to the axis AX and the tapered outer peripheral surface 2554T whose diameter increases toward the base end side (upward in the drawing). In addition, the four upper liquids are arranged such that the base end 258H1K located at the highest position of the peripheral edge of the upper liquid circulation hole 258H1 is positioned higher than the base end edge 2554K of the outer peripheral surface 2554T. The circulation holes 258H1 are respectively arranged. Further, the distal end 58H1S positioned at the lowest position among the peripheral edges of the upper liquid circulation hole 258H1 is positioned at the lower position than the proximal end edge 2554K of the outer peripheral surface 2554T.

By configuring in this way, as in the first embodiment, even when a bubble enters the surrounding area EH, the bubble BB does not stay around the tip portion 511 of the concentration sensor element 51, and is tapered. It rises along the outer peripheral surface 2554T and moves radially outward. Also, the bubbles that have moved to the outside in the radial direction are unlikely to return to the periphery of the distal end portion 2511 on the inside in the radial direction. Further, each upper liquid circulation hole 58H1 has a proximal end (upper end) 258H1K higher than the proximal end edge 2554K and a distal end (lower end) 258H1S lower than the proximal end edge 2554K. Therefore, bubbles near the base end edge 2554K can be easily discharged out of the protector 258 through the upper liquid circulation holes 258H1. That is, each upper liquid circulation hole 258H1 is not only a circulation of the urea aqueous solution NL but also a bubble discharge circulation hole that appropriately discharges the bubbles that have entered the enclosed region EH.
In the second embodiment as well, since the tip end surface 2554S of the holder member 255 is a flat surface orthogonal to the axis AX, any part of the hole peripheral edge 255H4F of the element holding hole 255H4 has the same height. Therefore, any part of the hole periphery 255H4F is the lowest hole periphery of the hole periphery 255H4F.

Further, in the holder member 255, the front end surface 2554S is a flat surface having the same height, and the outer peripheral surface 2554T is a tapered surface positioned higher than this. In other words, when comparing the respective portions of the distal end surface 2554S and the outer peripheral surface 2554T facing the surrounding region EH, the portion closer to the proximal end edge (surface peripheral edge) 2554K is higher or at the same height. It is made into the form which is located in. Specifically, the distal end surface 2554S is positioned at the same height as the hole peripheral edge 255H4F of the element holding hole 255H4 even when approaching the base end side edge (surface peripheral edge) 2554K. Further, in the outer peripheral surface 2554T, the portion closer to the base end side edge (surface periphery) 2554K is higher.
Moreover, as described above, the upper liquid circulation hole (bubble discharge circulation hole) 258H1 has its base end side end (upper end) 258H1K and the like higher than the base end side end edge (surface peripheral edge) 2554K of the outer peripheral surface 2554T. The distal end (lower end) 258H1S and the like are lower than the proximal end edge (surface periphery) 2554K of the outer peripheral surface 2554T.
Since the front end surface 2554S and the outer peripheral surface 2554T of the holder member 255 are configured in this way, also in the second embodiment, the bubbles that have reached the front end surface 2554S or the outer peripheral surface 2554T are moved radially outward along these surfaces, It can be easily discharged to the outside of the protector 258 from the upper liquid circulation hole 258H1 or the like.

Furthermore, the holder member 255 has a surrounding region surface (a distal end surface 2554S and an outer peripheral surface 2554T) in addition to a distal end surface 2554S around the element holding hole 255H4, as well as a surface peripheral side (base end side edge side) of the surrounding region surface. The outer peripheral surface 2554T is located at a position higher than the distal end surface 2554S and includes a base side surface peripheral edge 2554K that is a peripheral surface of the surrounding area surface.
By doing so, the outer peripheral surface 2554T is positioned higher than the front end surface 2554S and forms a “place”, so that once the bubble BB moves to the outer peripheral surface 2554T side, it is difficult to return to the front end surface 2554S side. . Therefore, the bubble BB that has entered the surrounding area EH can be reliably moved toward the base end side surface peripheral edge 2554K. In addition, even in the relationship with the upper liquid circulation hole (bubble discharge circulation hole) 58H1 and the like, the bubbles BB can be discharged more appropriately because of the above.
In addition, the front end surface 2554S and the outer peripheral surface 2554T in the second embodiment also correspond to the surrounding area surface in the present invention. The front end surface 2554S corresponds to the element peripheral surface, and the outer peripheral surface 2554T corresponds to the peripheral side surface.

  Next, in the sensor 2001 of the second embodiment, the upper liquid flow hole 258H1 of the protector 258, the flow hole 41R of the outer cylinder 41, the front end side surface 256S of the rubber bush 256, and the front end side surface 2601S of the positioning plate portion 2601 of the positioning member 620. Will be described with reference to FIGS. 15 and 16. The upper liquid flow hole 258H1 of the protector 258 corresponds to the flow hole and the bubble discharge flow hole of the surrounding member. Further, the flow hole 41R of the outer cylinder 41 corresponds to the outer flow hole and the bubble discharge outer flow hole of the outer surrounding member. Furthermore, the front end side surface 256S of the rubber bush 256 and the front end side surface 2601S of the positioning plate portion 2601 of the positioning member 260 correspond to the lower surface of the interposition member of the interposition member.

Similarly to the first embodiment, in the sensor 2001, the tip portion 411 of the cylindrical outer cylinder 41 is arranged around the horizontal direction H of the tip portion 511 of the density sensor element 51 and around the horizontal direction H of the protector 258. It is surrounded by a gap with H.258. Therefore, an outer surrounding region FH is formed between the tip 411 of the outer cylinder 41 and the protector 258.
The front end portion 411 of the outer cylinder 41 is provided with circulation holes 41R through which the aqueous urea solution NL can flow between the outer surrounding region FH and the outside in the horizontal direction H of the front end portion 411 of the outer cylinder 41 at equal intervals in the circumferential direction. Three are perforated. These three circulation holes 41R are all the same shape and are arranged at the same position in the axis AX direction (gravity direction G). This flow hole 41R not only allows the aqueous urea solution NL to flow, but as can be seen from FIGS. 15 and 16, its base end side end 41RK (upper end) is connected to the upper liquid flow hole 258H1 (bubble discharge). It is higher than the base end 258H1K (upper end) of the (circulation hole).

  Further, a rubber bush 256 and a positioning member 260 are interposed between the protector 258 and the tip 411 of the outer cylinder 41. The rubber bushing 256 and the positioning plate portion 2601 of the positioning member 260 are located on the base end side (upward in the drawing) of the outer surrounding region FH. Therefore, as described above, in addition to the front end side surface 2601S which is the lower surface of the positioning plate portion 2601 of the positioning member 260, a part of the front end side flat surface 256S1 and the notch 2563 of the front end side surface 256S of the rubber bush 256 are formed. The tip side oblique plane 256S2 faces the outer surrounding region FH. That is, the rubber bushing 256 and the positioning plate portion 2601 of the positioning member 260 corresponding to the interposition member have an interposition member lower surface KS2 indicated by a broken line in FIG. 16 by a part of the front end side surface 56S and the front end side surface 2601S. It is composed.

However, unlike the first embodiment, the interposed member lower surface KS2 in the second embodiment has a notch in the front end side surface 256S of the rubber bushing 256 in addition to the front end side 2601S (lower surface) of the positioning plate portion 2601, which is almost entirely horizontal. The front side oblique plane 256S2 forming 2563 is included. FIG. 17 shows a cross-sectional view of the interposed member lower surface KS2, the protector 258, and the like when viewed from the distal end side.
Here, an annular portion located on the protector 258 side (inner side) of the interposed member lower surface KS is defined as an inner peripheral edge KSI2, and among these, the horizontal direction H (in the figure, the upper liquid flow hole 258H1 of the protector 258). Sites (four locations) located on the outside in the direction along the paper surface are defined as discharge hole corresponding portions KSIC2.

  Then, also in the second embodiment, each of the discharge hole corresponding portions KSIC2 in the inner peripheral edge KSI2 of the interposed member lower surface KS2 is higher than the proximal end 258H1K (upper end) of the corresponding upper liquid circulation hole 258H1. It can be seen that The bubble BB that has entered the enclosed area EH (inside the protector 258) is discharged out of the protector 258 through the upper liquid circulation hole 258H1. At this time, as described above, each discharge hole corresponding portion KSIC2 is positioned higher than the proximal end 258H1K (upper end) of the corresponding upper liquid circulation hole 258H1, so that the bubble BB is moved from the upper liquid circulation hole 258H1 to the outer side. It can be reliably discharged to the surrounding area FH.

  On the other hand, an annular portion located on the outer cylinder 41 side (outer side) of the interposition member lower surface KS is defined as an outer peripheral edge portion KSO2, and among these, the horizontal direction H (the left-right direction in the figure) of the flow hole 41R of the outer cylinder 41 Parts (three places) located on the inner side are referred to as an outer discharge hole corresponding part KSOC2. As described above, in the second embodiment, the positioning plate portion 2601 is provided with three notches 2601C, and the rubber bush 256 is provided with three notches 2563. Specifically, the rubber The tip side oblique plane 256S2 formed in the notch 2563 of the bush 256 corresponds to the outer discharge hole corresponding part KSOC2.

  As shown in FIGS. 16 and 17, each of the outer discharge hole corresponding portions KSOC2 (the tip side oblique plane 256S2 of the notch portion 2563) is higher than the tip side end 41RS of the corresponding flow hole 41R. Yes. Therefore, when the bubble BB is located in the vicinity of the outer discharge hole corresponding part KSIO2, it can be discharged out of the outer cylinder 41 through each flow hole 41R.

Moreover, in the second embodiment, of the outer peripheral edge KSO2 of the interposed member lower surface KS2, the outer discharge hole corresponding part KSOC2 (front end oblique plane 256S2) includes the inner peripheral edge KSI2 and the front end side surface 2601S of the positioning plate portion 2601. Etc., and is positioned higher than other parts (in FIG. 17, the back side of the drawing).
In this way, the outer discharge hole corresponding portion KSOC2 (tip-side oblique plane 256S2) is positioned higher than the tip side surface 2601S and the like of the positioning plate portion 2601 to form a “place”, so that the bubble (bubble group) BB However, once it moves to the vicinity of the tip side oblique plane 256S2, it is difficult to return to the inner peripheral edge KSI2 which is lower than that and further into the protector 258. That is, as shown in FIGS. 16 and 17, the bubbles (bubble groups) BB that have entered the surrounding area EH, are discharged from the upper liquid circulation hole 258H1, and have entered the outer surrounding area FH are reliably discharged. It can be moved toward the corresponding part KSOC2 (tip-side oblique plane 256S2).
Thus, the bubbles BB in the vicinity of the outer discharge hole corresponding part KSOC2 can be discharged out of the outer cylinder 41 more reliably through the flow hole 41R, so that the influence of the bubbles on the concentration detection and the like can be reliably prevented.

  In addition, when there is little liquid flow and vibration, a bubble moves along the interposed member lower surface KS2 from the discharge hole corresponding part KSIC2 to the outer discharge hole corresponding part KSOC2. As is clear from FIG. 16, the interposition member lower surface KS is higher than the proximal end 258H1K (upper end) of the upper liquid circulation hole 258H1. Therefore, the bubbles (bubble groups) BB once discharged from the upper liquid circulation hole 258H1 to the outer surrounding area FH are prevented from flowing back into the surrounding area EH (inside the protector 258) through the upper liquid circulation hole 258H1. Yes.

  Next, the operation of the liquid concentration sensor unit 5 of the sensor 2001 in detecting the concentration of the urea aqueous solution NL is the same as that of the sensor 1 of the first embodiment, and thus the description thereof is omitted.

In the above, the present invention has been described according to the first and second embodiments and the modified embodiments. However, the present invention is not limited to the above-described embodiments and the like, and may be appropriately changed without departing from the gist thereof. Needless to say, this is applicable.
For example, in the first and second embodiments described above, the liquid state detection sensors 1, 1001, 2001 exemplify a type of sensor in which the liquid level sensor unit 4 and the liquid concentration sensor unit 5, 2005 are combined. However, the present invention can also be applied to a device that does not have a function as a liquid level sensor and that does not include an outer cylinder. In the first embodiment described above, the method of detecting the concentration of the urea aqueous solution NL in the liquid concentration sensor unit 5 has been described. However, urea concentration is determined based on the resistance value immediately after energization of the concentration sensor element 51 (internal heater wiring 518). The liquid temperature of the aqueous solution NL can also be measured. Therefore, in addition to the concentration of the urea aqueous solution NL, it can also be used as a liquid temperature sensor for measuring the liquid temperature.
Further, in the first embodiment and the like, the liquid state detection sensor 1 is exemplified as having the wiring board 22 on which the control circuit is mounted. However, the liquid state detection sensor of the present invention only needs to include a liquid concentration detection element, a holder member that holds the liquid concentration detection element, a surrounding member, and the like, and includes a liquid state detection sensor that does not include a control circuit.

In the above-described first embodiment, all of the liquid circulation holes 58H1 to 58H4 formed in the side portion 581 of the protector 58 have their proximal end (upper end) 58H1K and the like higher than the distal end surface 554S of the holder 55. Further, the distal end (lower end) 58H1S and the like are arranged so as to be positioned lower than the proximal end edge 554K.
Further, any of the liquid circulation holes 58H1 to 58H4 has a base end (upper end) 58H1K or the like higher than the base end side edge 554K of the outer peripheral surface 554T of the holder 55, and a front end side end (lower end). ) 58H1S and the like are also positioned so as to be positioned lower than the base end side edge 554K. The same applies to the second embodiment.
However, it is sufficient that at least one of the liquid circulation holes satisfies the above relationship. However, the more liquid circulation holes (bubble discharge circulation holes) that satisfy the above-described relationship, the more appropriately the bubbles can be discharged.

  In the first embodiment described above, a tapered outer peripheral surface 554T is provided in addition to the tip surface 554S around the element holding hole 55H4 of the holder member 55, and a triangular cross-section is provided around the tip surface 554S. It was. However, instead of the tapered outer peripheral surface 554T, a stepped outer peripheral surface located on the base end side (upward in the drawing) may be provided with respect to the distal end surface 554S, and a corner having a rectangular cross section may be provided.

In the first embodiment described above, the discharge hole corresponding portions KSIC corresponding to the liquid circulation holes 58H1 and the like formed in the protector 58 are all the proximal end 58H1K of the corresponding liquid circulation holes 58H1 and the like (bubble discharge flow holes). And so on (upper end).
Also, the outer discharge hole corresponding parts KSOC corresponding to the flow holes 41R formed in the outer cylinder 41 are all higher than the base end side end 41RK (upper end) of the corresponding flow hole 41R (bubble discharge outer flow hole). did. The same applies to the second embodiment.
However, it is sufficient that at least one of the bubble discharge circulation holes and the bubble discharge outer circulation holes satisfy the above-described relationship. However, as the number of the bubble discharge circulation holes and the bubble discharge outer circulation holes satisfying the above relationship increases, the bubbles can be discharged appropriately.

2 is a partially broken cross-sectional view of a liquid state detection sensor according to Embodiment 1. FIG. The external appearance of the rubber bush and protector in the liquid concentration sensor part of a liquid state detection sensor is shown. It is a longitudinal cross-sectional view of a liquid concentration sensor part among the liquid state detection sensors concerning Embodiment 1. FIG. It is a longitudinal cross-sectional view of the liquid concentration sensor part in the longitudinal cross section orthogonal to the longitudinal cross-sectional view of FIG. It is explanatory drawing which shows the positional relationship of a density | concentration sensor element, a holder member, and a protector, (a) is the elements on larger scale of the longitudinal cross-sectional view shown in FIG. 3, (b) is the elements on larger scale of the longitudinal cross-sectional view shown in FIG. It is. (A) is explanatory drawing which shows each form and connection form of a density sensor element, a connection terminal, and a lead wire, (b) is a side view of the front-end | tip part of a density sensor element. It is a figure which shows the shape of a protector, (a) is a front view, (b) is a side view, (c) is a bottom view, (d) is a longitudinal cross-sectional view. It is a figure which shows the shape of a holder member, (a) is a front view, (b) is a bottom view, (c) is a longitudinal cross-sectional view. It is explanatory drawing which shows the mode of a coupling | bonding of a holder member and a protector. It is a perspective view which shows the shape of a positioning member. It is a perspective view which shows the shape of a baffle member. It is explanatory drawing which shows the positional relationship of a protector, an outer cylinder, a rubber bush, and a positioning member which expands and shows a part of longitudinal cross-sectional view shown in FIG. It is the elements on larger scale of the longitudinal cross-sectional view which shows the positional relationship of a concentration sensor element, a holder member, and a protector concerning a deformation | transformation form. It is a fragmentary sectional view of the liquid state detection sensor according to the second embodiment. It is a longitudinal cross-sectional view of a liquid concentration sensor part among the liquid state detection sensors concerning Embodiment 2. FIG. It is explanatory drawing which shows the positional relationship of a protector, an outer cylinder, a rubber bush, and a positioning member which expands and shows a part of longitudinal cross-sectional view shown in FIG. FIG. 6 is a transverse sectional view showing a positional relationship among a protector, an outer cylinder, a rubber bush, and a positioning member in a liquid state detection sensor according to a second embodiment, as viewed from the front end side. It is a perspective view of the rubber bush used in Embodiment 2. The shape of a rubber bush is shown, (a) is a front view (side view), (b) is a plan view, (c) is a longitudinal sectional view, and (d) is a bottom view. It is a perspective view in the state where the positioning member and rectification member used in Embodiment 2 were combined. The shape of a positioning member and a rectification | straightening member is shown, (a) is a front view (side view), (b) is a top view, (c) is a longitudinal cross-sectional view, (d) is a bottom view.

Explanation of symbols

1, 1001, 2001 Liquid state detection sensor AX (Liquid state detection sensor) Axis 2, 2002 Base 3, 2003 Sensor unit 4 Liquid level sensor unit 41 Outer cylinder (outer surrounding member)
41R flow hole (outer flow hole, bubble discharge outer flow hole)
41RK Base end (upper end)
41RS End of the distribution hole (lower end)
411 Tip 42 Inner cylinder (holding tube)
421 (Inner cylinder) tip part 5, 2005 Liquid concentration sensor part 51 Concentration sensor element (liquid concentration detection element)
510 Temperature rising detection portion 511 Tip portion 511A (front end) main surface 511B (tip end) back surface 511AS (included in the temperature rising detection portion of the main surface) temperature rising portion main surface 511BS (temperature rising detection out of the back surface) Heater part back surface 518 Internal heater wiring 55, 155, 255 Holder member 55H Holder through hole 55H1 Inner cylinder holding hole 55H1A Inner cylinder separation facing surface 55H1B, 55H1C Inner cylinder proximity facing surface 55H1T Liquid introduction taper surface 55G1, 55G2 O-ring insertion groove 55H4, 155H4, 255H4 Element holding hole 55H4F, 155H4F, 255H4F (element holding hole) hole periphery (lowest hole periphery)
55D Inner cylinder contact surface 554, 1554, 2554 Tip taper portion 554T, 1554T, 2554T (of tip taper portion) outer peripheral surface (enclosed area surface, peripheral side surface)
554K, 1554K, 2554K (outer peripheral surface) proximal end edge (surface peripheral surface of surrounding area surface)
554J Front end side edges 554S and 2554S (outer peripheral surface) Front end surface (enclosed area surface, element peripheral surface)
56,256 Rubber bushing (intervening member)
56H, 256H Holder holding hole 56S, 256S Front side surface (lower surface of interposed member)
256S1 Tip-side flat surface 256S2 Tip-side oblique plane 561, 2561 Bush body 2563 Notch 571, 572 O-ring 58, 258 Protector (enclosure member)
581, 2581 Side portion 582, 2582 Bottom portion 58H1, 58H2, 58H3, 58H4 Liquid circulation hole (bubble discharge circulation hole)
258H1 Upper liquid flow hole (bubble discharge flow hole)
258H2 Lower liquid flow hole 58H41 Circular hole part 58H42 Slit part 58H1K, 58H2K, 58H3K, 58H4K (of liquid flow hole) Base end side end (upper end)
58H1S, 58H2S, 58H3S, 58H4S (of liquid flow hole) tip side end (lower end)
258H1K (upper liquid flow hole) proximal end (upper end)
258H1S (upper liquid flow hole) tip side end (lower end)
58H6, 58H7, 58H8, 258H6 Lower flow hole EH Surrounding region 60, 260 Positioning member (intervening member)
601 and 2601 Positioning plate portions 601H and 2601H Insertion holes 601S and 2601S Front side surface (lower surface of the interposed member)
2601C Notch part 602, 2602 (of positioning plate part) Leg part 602K, 2602K Engagement claw part
61,261 Rectifying member 611,26111 Rectifying plate part 612,2612 Leg part 612K, 2612K Engagement claw part G Gravitational direction H Horizontal direction FH Outer surrounding area KS, KS2 Interposing member bottom surface KSI, KSI2 (on the bottom surface of the interposing member) Part KSIC, KSIC2 (outside member lower surface) discharge hole corresponding part KSO, KSO2 (outside member lower surface) outer peripheral edge KSOC, KSOC2 (outside member lower surface) outer discharge hole corresponding part BB Bubble group NL Urea aqueous solution (liquid)

Claims (8)

A liquid state detection sensor for detecting a liquid state,
A liquid concentration detecting element for detecting the concentration of a specific component in the liquid;
A holder member configured to hold the liquid concentration detection element in a state where the tip of the liquid concentration detection element protrudes from its own element holding hole;
An encircling member,
When the liquid state detection sensor is in a posture in which the protruding direction of the tip of the liquid concentration detection element is the direction of gravity,
The surrounding member is
Of the tip portion of the liquid concentration detection element, at least the periphery in the horizontal direction is surrounded with a gap from the tip portion,
A surrounding member formed with one or a plurality of flow holes through which the liquid can flow inside and outside the surrounding region surrounded by the surrounding member;
The holder member is
Any part of the surrounding area surface facing the surrounding area is configured to be located higher or at the same height as the lowest lowest hole edge among the hole edges of the element holding hole,
At least one of the flow holes is a liquid state detection sensor which is a bubble discharge flow hole whose upper end is higher than the peripheral edge of the lowest hole and whose lower end is lower than the peripheral edge of the surrounding area surface. The liquid state detection sensor according to claim 1,
The holder member is
When any part of the surrounding area surface is compared with each part, the part on the side close to the surface periphery of the surrounding area surface is configured to be located at the same height or higher.
The bubble discharge / circulation hole is a liquid state detection sensor in which an upper end of the bubble discharge / circulation hole is higher than a peripheral edge of the surrounding area surface. The liquid state detection sensor according to claim 2,
The holder member is
The surrounding area surface is located on the element surrounding surface around the element holding hole and on the surface peripheral side of the surrounding area surface with respect to the element surrounding surface, and includes the surface periphery of the surrounding area surface, and the element surrounding surface A liquid state detection sensor configured to form a peripheral side surface that is higher than the peripheral side surface. The liquid state detection sensor according to claim 2,
The holder member is
A liquid state detection sensor in which the surrounding area surface is configured to become higher from the peripheral edge of the element holding hole toward the peripheral edge of the surrounding area surface. The liquid state detection sensor according to any one of claims 1 to 4,
The tip of the liquid concentration detecting element is
Main surface,
Having a flat plate shape including a back surface located on the back side of the main surface, and
The tip portion includes, in part, a temperature rise detection unit that raises temperature by energization,
Of the main surface, the portion included in the temperature rise detection unit is the temperature rise unit main surface,
Among the back surfaces, when the portion included in the temperature rise detection unit and the temperature rise unit back surface,
The surrounding member is
A liquid state detection sensor in which each of the flow holes including the bubble discharge flow hole is disposed at a position not directly facing the temperature rising portion main surface and the temperature rising portion rear surface of the tip portion of the liquid concentration detecting element. . The liquid state detection sensor according to any one of claims 1 to 5,
An outer surrounding member surrounding the horizontal direction of the front end portion of the liquid concentration detection element and surrounding the horizontal direction of the surrounding member with a gap from the surrounding member;
An interposed member interposed between the surrounding member and the outer surrounding member,
The outer surrounding member has one or more outer circulation holes that allow the liquid to flow between an outer surrounding region between the outer surrounding member and the surrounding member and the outside in the horizontal direction of the outer surrounding member. Have
The interposition member is located above the outer surrounding area and has a lower surface of the interposing member facing the outer surrounding area;
At least one of the outer flow holes is a bubble discharge outer flow hole whose upper end is higher than the upper end of the bubble discharge flow hole,
The interposition member lower surface is
At least the discharge hole corresponding part located on the outer side in the horizontal direction of the bubble discharge circulation hole among the inner peripheral edge part thereof is higher than the upper end of the corresponding bubble discharge circulation hole,
At least the outer discharge hole corresponding part located on the inner side in the horizontal direction of the bubble discharge outer circulation hole among the outer peripheral edge of each of them is higher than the lower end of the corresponding bubble discharge outer circulation hole,
At least a part of the bubble group that has entered the surrounding area and is discharged from the bubble discharge circulation hole is discharged from the discharge hole corresponding portion, and the bubble discharge corresponding to the discharge hole corresponding portion of the lower surface of the interposition member is performed. A liquid state detection sensor configured to be movable to a portion corresponding to the outer discharge hole along a portion higher than the upper end of the flow hole. The liquid state detection sensor according to claim 6,
The liquid state detection sensor in which the lower surface of the interposition member of the interposition member is higher than the upper end of the bubble discharge circulation hole in any part. The liquid state detection sensor according to claim 6 or 7,
The intermediate member lower surface of the intermediate member is
A liquid state detection sensor in which at least the outer discharge hole corresponding portion is higher than the inner peripheral edge portion of the outer peripheral edge portion.

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