KR102483383B1 - Urea concentration measuring device and urea water sender and urea water tank including the same - Google Patents

Abstract

The urea concentration measuring device includes a concentration measuring device configured to measure urea concentration by detecting a wave propagating through urea water in a concentration measurement region between a transmitter and a receiver, and a shielding member disposed to surround the concentration measurement region. The shielding member has a plurality of through-holes capable of preventing air bubbles in the urea solution from entering the concentration measurement region and at least one air discharge hole through which air bubbles inside the concentration measurement region are discharged to the outside.

Description

Urea concentration measuring device and urea water sender and urea water tank having the same

The present invention relates to a urea concentration measuring device for measuring the urea concentration of urea water used in a selective catalytic reduction system. In addition, the present invention relates to a urea water sender and a urea water tank having a urea concentration measuring device.

As an example of an exhaust gas purification system for post-processing and purifying harmful substances contained in exhaust gas of an internal combustion engine such as a diesel engine, a Selective Catalytic Reduction (SCR) system is known in the art.

A selective catalytic reduction system (hereinafter simply referred to as 'SCR system') reduces nitrogen oxides (NOx) in the exhaust gas of an internal combustion engine to nitrogen and water through a catalytic reaction using urea as a reducing agent. The SCR system is supplied with an aqueous solution containing urea as a reducing agent (hereinafter simply referred to as 'urea water'). For this purpose, a urea water tank for storing urea water is employed in the SCR system. The urea water tank is equipped with a urea water sender that is connected to the urea water supply module of the SCR system and sends the urea water stored in the urea water tank to the SCR system and guides the urea water returned from the SCR system to the urea water tank. Korean Patent Publication No. 10-2013-0066834 discloses an example of such a urea water sender.

The urea concentration of urea water injected into the catalytic converter of the SCR system needs to be maintained at about 32.5 wt% to maintain an appropriate reduction reaction. When the urea concentration is lower than 32.5 wt%, smooth catalytic action is difficult to occur. In order to measure the urea concentration of urea water, a urea concentration sensor (in the art, such a urea concentration sensor is also referred to as a 'quality sensor') is disposed inside the urea water tank. The SCR system controls the amount of urea water injected into the catalytic converter based on the measured signal from the urea concentration sensor. For the ideal reduction of nitrogen oxides (NOx) contained in the exhaust gas of an internal combustion engine, reliable and precise measurement of an urea concentration sensor is required. As an example of such a urea concentration sensor, Korean Patent Publication No. 10-2012-0135207 discloses a sensor for measuring the urea concentration of urea water using ultrasonic waves. The urea concentration sensor using ultrasonic waves measures the urea concentration of the urea solution by measuring the speed and intensity of the ultrasonic waves propagating through the urea solution.

Republic of Korea Patent Publication No. 10-2013-0066834 Republic of Korea Patent Publication No. 10-2012-0135207

Among vehicles or machines using an internal combustion engine such as a diesel engine, vehicles or machines that must meet exhaust gas emission standards, an SCR system is installed together with a urea solution tank storing urea solution. When a urea water tank equipped with a urea concentration sensor using ultrasonic waves is used in these vehicles and machines, the urea concentration is at a predetermined level (about 32.5wt) in the absence of internal factors such as quality change of urea water and change in urea level. %), urea concentration sensors using ultrasonic waves may erroneously measure urea concentration. As a cause of this, it has been found that fine bubbles generated in the urea water in the urea water tank invade the measurement area of the urea concentration sensor and irregularly fluctuate the speed and intensity of ultrasonic waves passing through the measurement area.

Vibration and shaking of the vehicle or machine during operation or driving of the vehicle or machine cause the urea solution in the urea solution tank to fluctuate, whereby bubbles may be generated in the urea solution in the urea solution tank. In addition, the urea water returned from the SCR system into the urea water tank pours onto the surface of the urea water in the urea water tank, and even at this time, bubbles may be generated in the urea water. Considering the operating conditions of vehicles and machines equipped with diesel engines, air bubbles generated in the urea water in the urea water tank cannot be avoided. However, the urea concentration sensor using ultrasonic waves is very likely to cause erroneous measurement due to bubbles in the urea solution.

Further, in order to more strictly comply with emission standards of exhaust gas, in some vehicles or machines, an SCR system is connected with an engine control unit of an internal combustion engine. In this case, when the reduced amount of nitrogen oxide does not reach a predetermined exhaust gas emission standard due to a decrease in the concentration of urea water, the output of the internal combustion engine is forcibly reduced. As described above, when the urea concentration sensor incorrectly measures the urea concentration even though the urea concentration in the urea solution is maintained at a predetermined level due to the minute bubbles in the urea solution, an undesirable forcible decrease in output of the internal combustion engine may occur.

The present invention has been devised to solve the above-mentioned problems of the prior art, and provides a urea concentration measuring device that achieves reliable and precise measurement without causing erroneous measurement due to bubbles.

In addition, the present invention provides a urea water sender and a urea water tank having a urea concentration measuring device achieving reliable and precise measurement.

One aspect of the present invention provides a urea concentration measuring device for measuring urea concentration by being immersed in urea water. The urea concentration measuring device according to the embodiment is directly disposed inside the urea water tank for storing the urea water used in the selective catalytic reduction system, or is attached to a urea water sender mounted on the urea water tank and disposed inside the urea water tank. do. The urea concentration measuring device according to the embodiment measures the urea concentration of the urea solution by measuring the speed and intensity of ultrasonic waves propagating through the urea solution.

An urea concentration measuring device according to exemplary embodiments includes a concentration measuring device configured to measure urea concentration by detecting a wave propagating through the number of urea in a concentration measurement region between a transmitter and a receiver, and arranged to surround the concentration measurement region. It includes a shielding member to be. The shielding member has a plurality of through-holes capable of preventing air bubbles in the urea solution from entering the concentration measurement region and at least one air discharge hole through which air bubbles inside the concentration measurement region are discharged to the outside.

In example embodiments, the concentration measuring device may include an ultrasonic concentration measuring device that measures the urea concentration by detecting ultrasonic waves propagating through the urea concentration measurement region. The ultrasonic concentration meter is spaced apart from the ultrasonic transceiver that transmits and receives the ultrasonic wave and the reflector that is spaced apart from the ultrasonic transceiver and reflects the ultrasonic wave to the ultrasonic transceiver, or the ultrasonic transmitter that transmits the ultrasonic wave and the ultrasonic transmitter that transmits the ultrasonic wave It may include an ultrasonic receiver for receiving.

In exemplary embodiments, the urea concentration measuring device further includes a frame member coupled to the concentration measuring device and disposed in the concentration measuring region. The frame member has at least one opening, and the shield member is coupled to the frame member so that at least a portion thereof is located in the opening. Further, the frame member includes a first contact portion and a second contact portion positioned at both ends in the longitudinal direction, and a holding portion positioned between the first contact portion and the second contact portion and having the opening. In addition, the side shape of the frame member has any one of a triangle, a rectangle, a circle, and a semicircle, or a combination of two or more of the triangle, a rectangle, a circle, and a semicircle.

In exemplary embodiments, the urea concentration measuring device further includes a spacer coupled to the ultrasonic transceiver and the reflector or the ultrasonic transmitter and the ultrasonic receiver of the concentration meter and spaced them apart from each other. In embodiments including the frame member, the spacer extends inside the frame member.

In exemplary embodiments, the urea concentration measuring device further includes a support member supporting the concentration measuring device. The support member is coupled to a urea water sender or a urea water tank where the urea concentration measuring device is located. In addition, the support member may include a first bracket supporting the ultrasonic transceiver or ultrasonic transmitter of the density measuring device and a second bracket supporting the reflector or ultrasonic receiver of the concentration measuring device.

In example embodiments, the shielding member includes any one of a mesh structure having the through hole, a thin film structure having the through hole, and a porous structure having the through hole. The through hole may be formed to pass through the shielding member in a thickness direction of the shielding member. The size of the through hole may be in the range of about 20 μm to about 200 μm.

In example embodiments, the air discharge hole may be formed to penetrate the shielding member in a thickness direction of the shielding member. The air discharge hole may have a size ranging from about 1.7 mm to about 4 mm. The air discharge hole may include an upper air discharge hole positioned above the shielding member. The air discharge hole may further include a lower air discharge hole positioned below the shielding member.

In example embodiments, the shielding member includes a bubble collection region connected to the concentration measurement region and disposed in a direction of gravity from the concentration measurement region, and bubbles generated in the concentration measurement region are directed to the bubble collection region. can move The air discharge hole may communicate with the bubble collection area.

Another aspect of the present invention provides a urea water sender mounted on a urea water tank for a selective catalytic reduction system. The urea water sender of the embodiment includes a suction pipe through which urea water is sucked from the urea water tank, a return pipe through which the urea water is returned to the urea water tank, a heating pipe for heating the urea water, and a holder coupled to the heating pipe. provide In addition, the urea number sender of the embodiment includes the urea concentration measuring device according to the above-described embodiment.

Another aspect of the present invention provides a urea water tank for storing urea water used in a selective catalytic reduction system. The urea water tank of one embodiment includes the urea concentration measuring device according to the above-described embodiment coupled to the inner bottom wall. Another embodiment of the urea water tank includes the above-described urea water sender equipped with the above-described urea concentration measuring device.

According to the urea concentration measuring device according to exemplary embodiments, by a shielding member that prevents bubbles in the urea solution from penetrating into a concentration measurement region where ultrasonic waves propagate and discharges the bubbles in the concentration measurement region to the outside, the urea concentration is introduced into the concentration measurement region, but bubbles in the urea solution do not penetrate into the concentration measurement region, and internal bubbles can be easily discharged to the outside. Therefore, the urea concentration measuring device according to the exemplary embodiments does not cause erroneous measurement due to air bubbles and realizes highly reliable and precise urea concentration measurement.

1 is a block diagram illustrating a selective catalytic reduction system according to exemplary embodiments.
Figure 2 is a perspective view showing a urea number sender having a urea concentration measuring device according to an exemplary embodiment.
Fig. 3 is a front view of the urea water sender shown in Fig. 2;
Fig. 4 is a perspective view illustrating a urea concentration measuring device according to exemplary embodiments.
Fig. 5 is a perspective view showing the urea concentration measuring device shown in Fig. 4 from which the shielding member and the frame member are removed.
Fig. 6 is a front view showing the urea concentration measuring device shown in Fig. 4 with the shield member and frame member removed.
7 is a perspective view showing a shield member and a frame member.
8 is a plan view showing a frame member.
9 is an enlarged view illustrating an example of a shielding member.
10 is an enlarged view showing another example of a shielding member.
11 is an enlarged view showing still another example of a shielding member.
12 is a perspective view showing another example of a frame member.
Fig. 13 is a perspective view showing still another example of a frame member.
Fig. 14 is a perspective view showing still another example of a frame member.
Fig. 15 is a perspective view showing still another example of a frame member.
16 is a front view schematically illustrating a urea concentration measuring device according to exemplary embodiments.
17 is an exploded perspective view illustrating a urea water sender coupled to a urea water tank according to exemplary embodiments.
FIG. 18 is a perspective view of the urea water tank shown in FIG. 17, showing that a urea water sender is mounted on the urea water tank by taking a longitudinal section of the urea water tank.
19 is a graph showing measured values of the concentration of urea water measured using the urea concentration measuring device of Comparative Example.
Figure 20 is a graph showing the measured value of the concentration of the number of urea measured using the urea concentration measuring device of one embodiment.
21 is a perspective view illustrating a urea water sender having a urea concentration measuring device according to exemplary embodiments.
22 is a view showing the urea concentration measuring device of FIG. 21;
23 is a perspective view illustrating a shield member and a frame member of the urea concentration measuring device of FIG. 21;
24 is a side view illustrating the shield member and the frame member of FIG. 23;
25 is a bottom perspective view illustrating the shield member and the frame member of FIG. 23;
FIG. 26 is a graph showing the air distribution in the urea concentration measuring device according to the size of the air discharge hole measured using the urea concentration measuring device of FIG. 21 .
FIG. 27 is a graph showing air distribution in the urea concentration measuring device according to the presence or absence of a lower air discharge hole in the urea concentration measuring device of FIG. 21 .
FIG. 28 is a graph showing the concentration measurement deviation according to the size of the air discharge hole measured using the urea concentration measuring device of FIG. 21 .
FIG. 29 is a graph showing a concentration measurement deviation according to a size of a through hole measured using the urea concentration measuring device of FIG. 21 .
FIG. 30 is a graph showing the stabilization time of the concentration change according to the size of the through hole measured using the urea concentration measuring device of FIG. 21 .

An embodiment of the urea concentration measuring device according to the present invention and an embodiment of a urea water sender and a urea water tank having the same will be described with reference to the accompanying drawings. Like reference numerals in the drawings indicate identical or corresponding components or parts.

First, with reference to FIGS. 1 to 18 , a urea concentration measuring device according to exemplary embodiments will be comprehensively described.

The urea concentration measuring device (100 in FIGS. 1 and 2, 100A in FIG. 16) according to exemplary embodiments is immersed in urea water used in a selective catalytic reduction system to measure the urea concentration of the urea water (FIG. 1). The urea concentration measuring devices 100 and 100A according to exemplary embodiments use ultrasonic waves and measure the velocity and intensity of ultrasonic waves propagating through a medium (the number of elements). The urea concentration measuring apparatus 100 or 100A according to exemplary embodiments includes a transmitter for transmitting ultrasonic waves and an ultrasonic receiver for receiving ultrasonic waves transmitted from the transmitter and propagating through a medium (urea water). Accordingly, a space in which ultrasonic waves propagate through the urea water is limited between the ultrasonic transmitter and the ultrasonic receiver. That is, the urea concentration measuring apparatus 100, 100A according to exemplary embodiments measure the urea concentration by measuring the speed and intensity of ultrasonic waves propagating through the number of urea located in the space between the ultrasonic transmitter and the ultrasonic receiver do. In the present specification, a space in which ultrasonic waves propagate through the number of elements between the ultrasonic transmitter and the ultrasonic receiver is referred to as a concentration measurement region.

The urea concentration measuring device may include an ultrasonic concentration meter, but is not limited thereto. The urea concentration measuring device may measure the concentration of the urea by measuring the properties of a wave propagating through a medium (the number of urea) using electromagnetic waves or lasers having a specific wavelength. In this case, the urea concentration measuring device may include a transmitter and a receiver, and a concentration measuring device for measuring the urea concentration by detecting a wave propagating through the number of urea in a concentration measurement area between the transmitter and the receiver. can

In an exemplary embodiment, the urea concentration measuring apparatus 100 may include an ultrasonic transceiver ( 111 in FIG. 4 ) in which the ultrasonic transmitter and the ultrasonic receiver are integrated. In this embodiment, the urea concentration measuring device 100 may include a reflector ( 112 in FIG. 5 ) that reflects ultrasonic waves transmitted by the ultrasonic transceiver 111 back to the ultrasonic transceiver. The concentration measurement region in this embodiment is located between the ultrasonic transceiver 111 and the reflector 112 and includes a space in which ultrasonic waves propagate through the urea water. In another embodiment, the urea concentration measuring device 100A does not include a reflector 112, and an ultrasonic transmitter (111T in FIG. 16) and an ultrasonic receiver (111R in FIG. 16) are spaced apart from each other in the traveling direction of ultrasonic waves. ) can be provided. The concentration measurement region in this embodiment is located between the ultrasonic transmitter 111T and the ultrasonic receiver 111R and includes a space in which ultrasonic waves propagate through the urea water.

The urea concentration measuring devices 100 and 100A according to exemplary embodiments may include a shielding member (140 in FIG. 4, 140A in FIG. 10, and 11 in FIG. 140B) in The shielding members 140, 140A, and 140B block the urea solution located within the concentration measurement region from air bubbles generated in the urea solution located outside the concentration measurement region. In addition, the shielding members 140, 140A, and 140B block the concentration measuring region from foreign substances included in the urea solution positioned outside the concentration measuring region. The shielding members 140, 140A, and 140B may be disposed to surround at least a portion or the entirety of the concentration measurement region. The shielding members 140, 140A, and 140B have a plurality of through holes (141 in FIG. 9, 141A in FIG. 10, and 141B in FIG. 11) sized to prevent air bubbles from entering the concentration measurement region. . Accordingly, the shielding members 140, 140A, and 140B screen or filter the air bubbles through the through holes 141, 141A, and 141B to prevent the air bubbles from entering the concentration measurement region. The through holes 141, 141A, 141B of the shielding members 140, 140A, 140B may be regularly or irregularly arranged, and some or all of them cover the shielding members 140, 140A, 140B in the thickness direction of the shielding member. It may be formed in the shield member (140, 140A, 140B) to pass through.

The shielding members 140, 140A, 140B are coupled to the ultrasonic transceiver 111 at one end and coupled to the reflector 112 at the other end, or coupled to the ultrasonic transmitter 111T at one end and coupled to the ultrasonic receiver at the other end. (111R) may be arranged to surround the concentration measurement region in such a way. Alternatively, the shielding members 140, 140A, and 140B may be frame members (150 in FIG. 4, 150A in FIG. 12, 150B in FIG. 13, and 150C in FIG. 14) configured to hold the shielding member in the concentration measurement region. , 150D in FIG. 15 and 150E in FIG. 16) may be arranged in the concentration measurement region. In the embodiment including the frame member, the frame member is coupled to the ultrasonic transceiver 111 and the reflector 112 at each end in the longitudinal direction, or coupled to the ultrasonic transmitter 111T and the ultrasonic receiver 111R. . The frame member may be coupled to the ultrasonic transceiver 111 and the reflector 112 or to the ultrasonic transmitter 111T and the ultrasonic receiver 111R through a sealant or a sealing member. That is, the frame member enters the concentration measurement area only through the shielding members 140, 140A, and 140B in the ultrasonic transceiver 111 and the reflector 112 or in the ultrasonic transmitter 111T and the ultrasonic receiver 111R. can be tightly coupled to The frame member has at least one opening (156 in FIG. 8, 156A in FIG. 12, 156B in FIG. 13, 156C in FIG. 14, 156D in FIG. 15), and the shield member is It may be attached to the outer or inner surface of the frame member so as to be positioned in the opening, or integrally molded with the frame member. Further, one shield member may be coupled to the frame member so as to be positioned in the opening in part or all thereof, and the shield member may be coupled to the frame member such that the same number of shield members as the opening in the frame member is positioned in each opening. It could be. The frame member coupled with the shield member functions as a modular component and can be easily attached to the ultrasonic transceiver 111 and the reflector 112 or to the ultrasonic transmitter 111T and the ultrasonic receiver 111R.

The urea concentration measuring device 100, 100A according to the embodiment is a support member for fixing to a urea water sender (200 in FIGS. 1 and 2) or a urea water tank (300 in FIGS. 1 and 17) (FIG. 4 130 in , 130A in FIG. 16). The support member may consist of one part or two or more parts. In one embodiment, the support member supports the ultrasonic transceiver 111 and the reflector 112, and a part of the support member and the reflector 112 may be integrated. In another embodiment, the support member supports the ultrasonic transmitter 111T and the ultrasonic receiver 111R. The urea concentration measuring device having the support member and the frame member is composed of one measuring device, and can be easily installed in the urea water sender and the urea water tank.

The urea concentration measuring apparatus 100, 100A according to the embodiment is a distance that can be measured by ultrasonic waves in the ultrasonic propagation direction between the ultrasonic transceiver 111T and the reflector 112 or the ultrasonic transmitter 111T and the ultrasonic receiver 111R. A spacer spaced apart from each other is provided. In an embodiment with the spacer, the spacer may be arranged to extend inside the frame member. In another embodiment, the frame member may function as the spacer. Accordingly, in this embodiment, the ultrasonic transceiver 111 and the reflector 112 or the ultrasonic transmitter 111T and the ultrasonic receiver 111R may be separated by the frame member so that the density measurement is performed in the ultrasonic propagation direction.

Hereinafter, with reference again to FIGS. 1 to 18, specific embodiments of the urea concentration measuring device will be described in more detail.

1 schematically illustrates a selective catalytic reduction system to which a urea concentration measuring device, a urea water sender, and a urea water tank are applied according to an embodiment. Referring to FIG. 1 , a selective catalytic reduction system 400 (hereinafter simply referred to as 'SCR system 400') post-treats the exhaust gas of the internal combustion engine 10. The internal combustion engine 10 targeted by the SCR system 400 to which the embodiment of the present invention is applied includes, but is not limited to, diesel engines mounted on passenger cars, trucks, construction machines, agricultural machines, and ships.

The SCR system 400 reduces nitrogen oxides (NOx) in the exhaust gas of the internal combustion engine 10 to nitrogen and water through a catalytic reaction using urea contained in the urea solution as a reducing agent. The urea water used in the SCR system 400 is stored in the urea water tank 300 according to the embodiment. The urea water stored in the urea water tank 300 is supplied to the SCR system 400 through the urea water sender 200 according to the embodiment mounted in the urea water tank 300 . In addition, urea water not used in the SCR system 400 is returned to the urea water tank 300 through the urea water sender 200 . In one embodiment, the urea concentration measuring device 100 is attached to the urea water sender 200 and is located in the urea water tank 300.

The SCR system 400 includes a catalytic converter 410 in which urea and nitrogen oxides (NOx) are reduced through a catalytic reaction, a urea water supply module 420 for supplying urea water to the catalytic converter 410, A urea water injection module 430 for injecting urea water into the catalytic converter 410 and a dosing control unit 440 for controlling supply and injection of urea water are provided.

The catalytic converter 410 is connected to the exhaust pipe of the internal combustion engine 10 along the flow direction of the exhaust gas. Nitrogen oxides (NOx) in the exhaust gas from the internal combustion engine 10 are reduced to nitrogen and water in the catalytic converter 410 using urea of the urea water injected from the urea water injection module 430 as a reducing agent. The urea water injection module 430 is attached to the catalytic converter 410 and is connected to the urea water supply module 420 through a urea water supply pipe 461 . The urea water injection module 430 injects urea water into the catalytic converter 410 under the control of the dosing control unit 440 .

The urea water supply module 420 is connected to the urea water sender 200 through a urea water supply pipe 462 and a urea water return pipe 463. The urea water supply module 420 has a pump device for sucking urea water from the urea water tank 300 and returning the urea water to the urea water tank 300 therein. The urea water supply module 420 supplies an appropriate amount of urea water to the urea water injection module 430 under the control of the dosing control unit 440 . In addition, the urea water supply module 420 transfers the remaining urea water supplied to the urea water injection module 430 among the urea water sucked from the urea water tank 300 through the urea water return pipe 463 to the urea water tank ( 300).

The dosing control unit 440 is a measurement signal from the urea concentration measuring device 100 located in the urea water tank 300, an exhaust gas temperature sensor 451 and a NOx sensor 452 installed in the catalytic converter 410 ) Controls the operation of the urea water supply module 420 and the urea water injection module 430 based on the measurement signal from. That is, the dosing control unit 440 determines the amount of urea water supplied by the urea water supply module 420 to the urea water injection module 430 and the catalytic converter 410 by the urea water injection module 430 based on the measurement signal. ) to control the amount of urea water injected into In addition, the dosing control unit 440 includes a measurement signal from a sensor disposed in the urea water tank 300 and measuring the level of the water surface of the urea water, and a sensor disposed in the urea water tank 300 and measuring the temperature of the urea water. is input. In addition, the dosing control unit 440 is connected to the engine control unit 11 of the internal combustion engine 10, and the quality of the urea water (eg, the urea concentration of the urea water), the level of the urea water, the temperature of the urea water, etc. If it is out of this predetermined range, a signal related thereto is transmitted to the engine control unit 11 of the internal combustion engine 10.

If the vehicle or machine equipped with the internal combustion engine 10 is operated at a temperature below the freezing point of urea water (eg, minus 11° C.) and the urea water freezes, the SCR system 400 cannot operate. To thaw the frozen urea water and to prevent freezing of the urea water, the SCR system 400 includes a heating means for heating the urea water. In the application example shown in FIG. 1, the heating means includes cooling water of the internal combustion engine 10 as a heating heat source and a conduit for circulating the cooling water through the urea water tank 300 and the urea water injection module 430. do. In detail, the cooling water of the internal combustion engine 10 is supplied from the internal combustion engine 10 to the urea water sender 200 through the cooling water supply pipe 471 and is supplied from the urea water sender 200 through the cooling water return pipe 472. returned to the engine (10). In addition, the cooling water of the internal combustion engine 10 is supplied from the internal combustion engine 10 to the urea water injection module 430 through the cooling water supply pipe 473 and from the urea water injection module 430 through the cooling water return pipe 474. returned to the engine (10).

1 to 3, the urea concentration measuring device 100 of one embodiment is mounted on the urea water sender 200 of one embodiment, and the urea water tank 300 of one embodiment is installed even at a low level of urea water. It is arranged to be immersed in water. 4 to 10, the urea concentration measuring apparatus 100 according to an embodiment is positioned to face the ultrasonic transceiver 111 and the ultrasonic transceiver 111 in the propagation direction of ultrasonic waves, and the ultrasonic transceiver 111 A reflector 112 that reflects ultrasonic waves to the ultrasonic transceiver 111, a spacer 120 that separates the ultrasonic transceiver 111 and the reflector 112 in the propagation direction of the ultrasonic wave, and the ultrasonic transceiver 111 and the reflector 112 ) and a support member 130 for fixing them to a suitable place (eg, a suitable place inside the urea water tank 300 or the urea water sender 200) for measuring the urea concentration.

The ultrasonic transceiver 111 integrally includes a transmitter for transmitting ultrasonic waves and a receiver for receiving ultrasonic waves. The transmitter and receiver constituting the ultrasonic transceiver 111 may include a plurality of transducers having piezoelectric elements, but are not limited thereto. The reflector 112 is spaced apart from the ultrasonic transceiver 111 by a spacer 130 a distance at which good measurements of urea concentration are made by ultrasonic waves. The ultrasonic transceiver 111 faces the reflector 112 and has a transceiver 114 in the shape of a truncated cone, and a flat surface of the transceiver 114 facing the reflector 112 may be the transmit/receive surface 115. . The ultrasonic transceiver 111 transmits ultrasonic waves from the transmitting/receiving surface 115 toward the reflector 112 in the form of multiple pulse waves. Therefore, in this embodiment, the ultrasonic propagation direction of the urea concentration measuring device 100 includes a direction from the ultrasonic transceiver 111 toward the reflector 112 and a direction from the reflector 112 toward the ultrasonic transceiver 111. . In addition, the ultrasonic transceiver 111 has a wire 116 extending from the ultrasonic transceiver 111 . The wire 116 is connected to the above-described dosing control unit 440 or connected to the circuit board of the urea water sender 200. The measurement signal from the ultrasonic transceiver 111 is transmitted to the circuit board of the dosing control unit 440 or the urea water sender 200 through the wire 116.

In this embodiment, the support member 130 includes a first bracket 131 and a second bracket 132 made of a flat metal plate or a metal plate partially bent. The first bracket 131 may be coupled to the ultrasonic transceiver 111 and the second bracket 132 may be integrated with the reflector 112 . Thus, in this embodiment, the reflector 112 includes a surface facing the ultrasonic transceiver 111 of the second bracket 132 .

Also, in this embodiment, the spacer 120 includes three spacer bars 121, 122, and 123 having a bar shape of the same length. The spacer bars 121, 122, and 123 are arranged at equal intervals, one end of which is screwed to the ultrasonic transceiver 111 through the first bracket 131, and the other end of the reflector 112 and the second bracket ( 132) is screwed. In another embodiment, the spacer 120 may include a plate-shaped member.

Ultrasonic waves from the ultrasonic transceiver 111 propagate to the reflector 112 through the number of elements introduced into the space extending along the spacer bars 121, 122, and 123 between the ultrasonic transceiver 111 and the reflector 112, and Ultrasound from (112) propagates to the ultrasonic transceiver (111). In this embodiment, the space in which ultrasonic waves propagate through the elemental water includes at least a space located between the ultrasonic transceiver 111 and the reflector 112 . Therefore, in this embodiment, the concentration measuring region 113 of the urea concentration measuring device 100 is located between the ultrasonic transceiver 111 and the reflector 112, as schematically shown in FIG. It includes a space propagating between the transceiver 111 and the reflector 112.

2 to 4 and 7 to 10, the urea concentration measuring device 100 includes a shielding member 140 that blocks the concentration measurement region 113 from bubbles in the urea solution and the shielding member 140. A frame member 150 is provided to position the shielding member 140 so as to surround the concentration measurement region 113 between the ultrasound transceiver 111 and the reflector 112 by fixing it. The shielding member 140 is interposed between the ultrasonic transceiver 111 and the reflector 112 by the frame member 150 and surrounds part or all of the concentration measurement region 113 .

The shielding members 140 , 140A, and 140B are configured to block the concentration measurement region 113 from bubbles in the urea solution located outside the concentration measurement region 113 . The shielding member 140 has a plurality of fine through holes 141, 141A, and 141B. The through holes 141, 141A, and 141B have a size that allows urea water to flow into the concentration measurement region 113 and prevents bubbles generated in the urea solution from entering the concentration measurement region 113.

In one embodiment, the shield member 140 includes a mesh structure, and in this case, the through hole 141 may be one eye of the mesh structure. In one embodiment, the shielding member 140A includes a thin film structure having a plurality of fine through holes 141A. In one embodiment, the shield member includes a porous structure having a plurality of fine through holes (141B). That is, the shielding member of the urea concentration measuring device 100 according to the embodiment has a size that allows the inflow of urea water into the concentration measuring region 113 and prevents air bubbles in the urea solution from entering the concentration measuring region 113. It includes a mesh structure, a thin film structure or a porous structure having a plurality of through holes (141, 141A, 141B) made of. The mesh structure, thin film structure, or porous structure may be formed of a corrosion-resistant metal material or a synthetic resin material.

Considering the driving environment of a vehicle or machine employing the internal combustion engine 10, the size of bubbles generated in urea water varies. Therefore, the minimum size of the through holes 141, 141A, and 141B formed in the shielding members 140, 140A, and 140B is determined to a degree that allows passage of urea water into the concentration measurement region 113 while blocking air bubbles. . In addition, the maximum size of the through holes 141, 141A, and 141B is determined to a degree that can reliably block bubbles or foreign substances in the urea solution. As an example, the size of the through holes 141, 141A, and 141B ranges from 0.01 mm to 0.4 mm. When the size of the through hole is less than 0.01 mm, urea water may not smoothly flow into the concentration measurement region 113 through the shielding members 140, 140A, and 140B. In addition, when the size of the through hole is larger than 0.4 mm, the performance of the shielding members 140, 140A, and 140B to prevent intrusion of air bubbles or other foreign substances in the urea solution into the concentration measurement region 113 may deteriorate. As another example, when considering more effective blocking of air bubbles or foreign matter in urea solution, the range of sizes of the through holes 141, 141A, and 141B may be 0.02 mm to 0.2 mm. In one embodiment, the through hole may have a triangular, quadrangular, rhombic, circular, or elliptical shape, but is not limited thereto. Regarding the shape of the through hole, the size of the through hole is the length of one side when the through hole is triangular, the length of the diagonal when the through hole is square, rectangular or rhombic, the length of the diameter when the through hole is approximately circular, and the through hole If it is approximately elliptical, it can be defined as the length of its major axis.

9 shows an example of a shielding member including a mesh structure. The shielding member 140 of the mesh structure shown in FIG. 9 is a plain weave, twill weave, dutch weave, It may be formed by weaving in a manner such as twilled dutch weave. The thickness of the steel wire 142 is approximately 0.04 mm. The through hole 141 provided in the shielding member 140 includes one eye defined by the steel wire 142 as a warp yarn and the steel wire 143 as a weft yarn. The shape of the through hole 141 is square or rectangular, and the length in the diagonal direction is approximately 0.044 mm. Since the shielding member 140 is made of the steel wires 142 and 143 of stainless steel, heat transfer for preventing freezing of the urea water can be performed well through the shielding member 140 . As another example, the shielding member 140 of the aforementioned mesh structure may be formed by weaving synthetic resin yarns. 10 shows an example of a shielding member including a thin film structure. A shielding member 140A shown in FIG. 10 includes a thin film 144 made of a corrosion-resistant metal and a plurality of through holes 141A formed by penetrating the thin film 144 in the thickness direction. 11 shows another example of a shielding member. The shielding member 140B shown in FIG. 11 includes a porous structure 145 having a plurality of through holes 141B having different sizes.

4, 7, and 8, the frame member 150 fixes the shield members 140, 140A, and 140B so that the shield members 140, 140A, and 140B are connected to the ultrasonic transceiver 111 and the reflector 112. It is positioned so as to surround the concentration measurement region 113 between them. The frame member 150 may be formed of a synthetic resin material or a metal material.

In this embodiment, the frame member 150 is clamped by the first and second brackets 131 and 132, and is coupled to the ultrasonic transceiver 111 at one end and coupled to the reflector 112 at the other end. . The frame member 150 has the shape of a hollow triangular cylinder. The frame member 150 includes first and second contact portions 151 and 152 located at both ends in the longitudinal direction and contacting the first and second brackets 131 and 132, respectively, and the first and second contact portions 151. , 152 and has a retaining portion 153 having at least one opening 156. The first contact portion 151 contacts the first bracket 131 at an outer end surface in the longitudinal direction, and the second contact portion 152 contacts the second bracket 132 at an outer end surface in the longitudinal direction. The outer end surface in the longitudinal direction of the first contact portion 151 and the outer end surface in the longitudinal direction of the second contact portion 152 have flat surfaces, so that the frame member 150 is attached to the ultrasonic transceiver 111 and the reflector 112 or It can be airtightly coupled to the first bracket 131 and the second bracket 132. The shielding members 140 , 140A and 140B are fixed to the holding part 153 . The holding part 153 includes three horizontal bars 154 extending in the longitudinal direction of the frame member 150 and three vertical bars 155 extending between the horizontal bars 154 adjacent to each other in the middle of the horizontal bars 154. ). Thus, six openings 156 are formed between the horizontal bar 154 and the vertical bar 155, and the number of urea is measured in the concentration measurement area 113 through the shielding members 140, 140A, and 140B and the opening 156. It can flow into or out of. The outer surface of the transverse bar 154 includes a curved surface in the circumferential direction of the frame member 150 . The frame member 150 has a bubble discharge port 157 through which the inside and outside of the concentration measurement region 113 are communicated. Bubbles that may infiltrate into the concentration measurement region 113 may be discharged to the outside of the concentration measurement region 113 through the bubble outlet 157 . In the example shown in FIG. 7 , the bubble outlet 157 is formed in the shape of a groove on the upper side of the outer end surface of the second contact portion 152 in the longitudinal direction. The number and position of the bubble outlets 157 are not limited to the illustrated example.

The shield members 140 , 140A and 140B are coupled to the holding portion 153 of the frame member 150 such that a portion thereof is located in the opening 156 . In this embodiment, the shield members 140, 140A, and 140B are attached to the curved outer surface of the horizontal bar 154 and the outer surface of the vertical bar 155 in an adhesive manner. As another example of fixing between the shield members 140, 140A, and 140B and the frame member 150, when the frame member 150 is made of synthetic resin, the shield members 140, 140A, and 140B are placed in a molding mold and then injected. The shield members 140, 140A, and 140B and the frame member 150 may be integrally formed by molding. In the example shown in FIG. 7 , the shielding members 140, 140A, and 140B are attached to the entire holding portion 153, but as another example, the same number of shielding members 140, 140A, and 140B as the opening 156 may be located in each opening.

The frame member 150 to which the shield members 140, 140A, and 140B are attached is between the first and second brackets 131, 132 so that the spacer bars 121, 122, and 123 are located therein and extend therein. are interposed in When the frame member 150 to which the shield members 140, 140A, and 140B are attached is interposed between the first and second brackets 131 and 132, the truncated cone-shaped transceiver 114 of the ultrasonic transceiver 111 Being fitted into the first contact portion 151, the frame member 150 is positioned between the first and second brackets 131 and 132 without fluctuation. For example, in a state in which the spacer bars 121, 122, and 123 are coupled to the ultrasonic transceiver 111, the frame member 150 is inserted so that the spacer bars 121, 122, and 123 are inserted into the frame member 150. position, and the reflector 112 and the second bracket 132 are screwed to the other ends of the spacer bars 121, 122, and 123, so that the frame member 150 may be located in the concentration measurement area 113. Accordingly, the frame member 150 is airtightly coupled to the ultrasonic transceiver 111 through the first bracket 131 at one end and airtightly coupled to the reflector 112 through the second bracket 132 at the other end. In another embodiment, the frame member 150 is formed between the ultrasonic transceiver 111 and the reflector ( 112) can be hermetically coupled.

12 to 15 show several examples of frame members employed in the urea concentration measuring device of the embodiment. The frame member 150A shown in FIG. 12 has a hollow rectangular cylinder shape. The frame member 150A includes quadrangular first and second contact portions 151A and 152A, four horizontal bars 154A extending between the first and second contact portions 151A and 152A, and a horizontal bar 154A. ) has four vertical bars 155A extending between neighboring horizontal bars 154A in the middle. Six openings 156A are formed between the horizontal bar 154A and the vertical bar 155A, and the shield members 140, 140A, and 140B are formed on the frame member 150A so that at least some of them are located in the opening 156A. are combined A bubble outlet 157A is formed on the upper side of the outer end surface of the second contact portion 152A in the longitudinal direction.

The frame member 150B shown in FIG. 13 has a hollow cylindrical shape. The frame member 150B has ring-shaped first and second contact portions 151B and 152B and four horizontal bars 154B extending between the first and second contact portions 151B and 152B. Four openings 156B are formed between the first and second contact portions 151B and 152B and the horizontal bar 154B, and at least a portion of the shielding members 140, 140A, and 140B is positioned in the opening 156B. It is coupled to the frame member (150B) so as to. A bubble outlet 157B is formed on the upper side of the outer end surface of the second contact portion 152B in the longitudinal direction.

The frame member 150C shown in FIG. 14 has a lower half of a hollow square cylinder shape and an upper half of a hollow semicylinder shape. The first and second contact portions 151C and 152C of the frame member 150C have a semicircular upper part and a rectangular lower part. The frame member 150C has five horizontal bars 154C extending between the first and second contact portions 151C and 152C, and between the first and second contact portions 151C and 152C and the horizontal bar 154C. Five openings 156C are formed therein. The shielding members 140, 140A, and 140B are coupled to the frame member 150C such that at least a portion thereof is located in the opening 156C. A bubble outlet 157C is formed on the upper side of the outer end face of the second contact portion 152C in the longitudinal direction.

A frame member 150D shown in FIG. 15 has a shape similar to that of the frame member 150C shown in FIG. 14 . That is, the lower half of the frame member 150D has a hollow rectangular cylinder shape and the upper half has a hollow semi-cylindrical shape. The frame member 150D has one opening 156D at the bottom of the lower half, and the shielding members 140, 140A, and 140B are positioned in the opening 156D. Further, the frame member 150D has a protrusion 158D protruding upward from the upper end of the upper half, and a bubble outlet 157D is formed through the protrusion 158D.

As shown in FIGS. 7 and 12 to 15, the side shapes of the frame members 150, 150A, 150B, 150C, and 150D for fixing the shield members 140, 140A, and 140B are triangular, square, circular, and semicircular. Any one of them, or a combination of two or more of a triangular, quadrangular, circular, and semicircular shape may be formed. The support member 130, the ultrasonic transceiver 111, and the reflector 112 may be formed to complementarily correspond to the side shapes of the frame members 150, 150A, 150B, 150C, and 150D. In addition, the frame members 150, 150A, 150B, 150C, and 150D have at least one opening 156, 156A, 156B, 156C, and 156D in the holding portion 153 to which the shield members 140, 140A, and 140B are fixed. have In addition, the shielding members 140, 140A, and 140B may be attached to the outer or inner surface of the frame member, or integrally formed with the frame member.

16 schematically shows a urea concentration measuring device of another embodiment not provided with a reflector. The urea concentration measuring device 100A shown in FIG. 16 includes an ultrasonic transmitter 111T that transmits ultrasonic waves, an ultrasonic receiver 111R that receives ultrasonic waves transmitted from the ultrasonic transmitter 111T and propagated through urea water, A supporting member 130A supporting the ultrasonic transmitter 111T and the ultrasonic receiver 111R is provided. The support member 130A is coupled to the inner bottom wall of the urea water sender 200 or the urea water tank 300. The support member 130A includes a first bracket 131A supporting the ultrasonic transmitter 111T and a second bracket 132A supporting the ultrasonic receiver 111R.

The ultrasonic waves transmitted by the ultrasonic transmitter 111T propagate to the ultrasonic receiver 111R through the urea water flowing into the space between the ultrasonic transmitter 111T and the ultrasonic receiver 111R. Therefore, the concentration measuring region 113A of the urea concentration measuring device 100A includes the space between the ultrasonic transmitter 111T and the ultrasonic receiver 111R in which ultrasonic waves propagate through the urea water.

The urea concentration measuring device 100A includes the above-described shielding members 140, 140A, and 140B disposed in the concentration measuring region 113A to prevent air bubbles from entering the concentration measuring region 113A. The shielding members 140, 140A, and 140B may be attached to the ultrasonic transmitter 111T and the ultrasonic receiver 111R to surround the concentration measurement region 113A. The urea concentration measuring device 100A of this embodiment is coupled to the ultrasonic transmitter 111T and the ultrasonic receiver 111R, and is disposed in the concentration measuring region 113A, and the frame member 150E holding the shield members 140, 140A, and 140B. ) is provided. The frame member 150E may be formed similarly to the frame member 150 described above, and has at least one opening. The shielding members 140, 140A, and 140B are fixed to the frame member 150E so as to be positioned in the opening of the frame member 150E. Instead of the frame member 150E, one of the aforementioned frame members 150, 150A, 150B, 150C, and 150D may be used in the urea concentration measuring device 100A. Further, as shown in FIG. 16 , the urea concentration measuring device 100A may include a spacer 121A that separates the ultrasonic transmitter 111T and the ultrasonic receiver 111R in the propagation direction of ultrasonic waves.

The urea concentration measuring devices 100 and 100A of the above-described embodiment include frame members 150, 150A, 150B, 150C, 150D, and 150E for fixing the shield members 140, 140A, and 140B. An apparatus for measuring urea concentration of another embodiment may have a structure in which the frame members 150, 150A, 150B, 150C, 150D, and 150E and the spacer 120 are integrated. For example, the structure may have at least one opening passing through the concentration measurement regions 113 and 113A, and the shielding members 140, 140A and 140B may be positioned in the opening, and ultrasound waves may be provided at both ends of the structure, respectively. The transceiver 111 and the reflector 112 may be combined, or the ultrasonic transmitter 111T and the ultrasonic receiver 111R may be coupled.

In the urea concentration measuring apparatus 100 or 100A according to the embodiment, the shielding member 140 , 140A or 140B at least partially encloses the concentration measuring regions 113 or 113A, so that the urea water in the urea water tank 300 is measured. Bubbles cannot penetrate into the concentration measurement regions 113 and 113A. Therefore, the urea concentration measuring device 100 or 100A according to the embodiment eliminates the possibility of erroneous measurement caused by bubbles. In addition, when the shielding members 140, 140A, and 140B are made of a metal material, heat is easily transferred to the urea water located in the concentration measuring regions 113 and 113A, and the frozen urea water in the concentration measuring regions 113 and 113A It can be readily thawed or can be prevented from freezing.

The urea concentration measuring devices 100 and 100A of the above-described embodiment are attached to the urea water sender 200 according to the embodiment by the support members 130 and 130A and are arranged to be immersed in urea water in the urea water tank 300 do. Referring to FIGS. 2, 3, 17 and 18, the urea number sender 200 according to the embodiment including the above-described urea concentration measuring device 100 will be described.

The urea water sender 200 is removably mounted on the tank body 310 of the urea water tank 300. In one embodiment, the urea water sender 200 includes a suction pipe through which urea water in the tank body 310 is sucked, and a return pipe through which urea water not supplied to the urea water injection module 430 is returned to the tank body 310. to provide In addition, the urea water sender 200 is provided with a heating tube for heating the urea water to thaw the frozen urea water or to prevent freezing of the urea water. In addition, the urea water sender 200 includes a sensor for measuring the level of the urea water in the tank body 310 (eg, the urea water level sensor 260 shown in FIG. 3) and a sensor for measuring the temperature of the urea water. (not shown), a sensor for measuring the urea concentration of the urea water (eg, the urea concentration measuring device 100 or 100A of the above-described embodiment) is provided. The urea water sender 200 includes a support that is removably attached to the tank body 310 and holds the suction pipe, the return pipe, the heating pipe, and the like. The suction pipe, the return pipe, the heating pipe, etc. are provided on the support to extend into the inside of the tank body 310 through the support.

The urea water sender 200 functions as the support and has a sender head 210 removably mounted on the tank body 310. The sender head 210 includes a housing 211 in which a fluid passage communicating with the suction pipe, the return pipe, and the heating pipe is formed and a circuit board is mounted. The housing 211 has a disc portion forming a base and a protrusion protruding upward in a semi-cylindrical shape toward the disc portion. The urea water sender 200 has a flange 212 and a packing 213 formed in the mounting hole 315 formed in the tank body 310 of the urea water tank 300 in the disk portion of the housing 211 of the sender head 210. ) and is mounted using screw fastening. Inside the protruding portion, a circuit board to which wires from the aforementioned sensors are connected is mounted, and the protruding portion is closed by a cap 214. This circuit board is electrically connected to the connector 215 provided on the side of the protrusion of the housing 211 . The connector 215 is electrically connected to a corresponding connector provided on a wire extending from the dosing control unit 440 of the SCR system 400. Therefore, the measurement signal from the sensor disposed in the urea water sender 200 is transferred to the dosing control unit 440 of the SCR system 400.

The sender head 210 includes the cooling water supply pipe 471 of the internal combustion engine 10, the cooling water return pipe 472 of the internal combustion engine 10, the urea water supply pipe 462 of the urea water supply module 420, and the urea water supply module. First to fourth pipe connectors 221, 222, 223, and 224 for connection with the urea water return pipe 463 of the 420 are provided. In addition, an air vent pipe 225 communicating the inside and outside of the tank body 310 is provided in the sender head 210 .

The urea water sender 200 includes a suction pipe 231 through which urea water inside the tank body 310 is sucked and a return pipe 232 through which urea water returned from the urea water supply module 420 is returned to the inside of the tank body 310. provide The urea water inside the tank body 310 is transferred to the urea water supply module 420 through the suction pipe 231 by the pump device inside the urea water supply module 420 . The upper end of the suction pipe 231 is connected to the lower surface of the housing 211 of the sender head 210 and communicates with the third pipe connector 223 through a fluid passage passing through the housing 211. The suction pipe 231 extends downward from the housing 211 . The return pipe 232 is connected to the lower surface of the housing 211 at its upper end and communicates with the fourth pipe connector 224 through a fluid passage passing through the housing 211 . The lower end of the return tube 232 is located slightly lower than the lower surface of the housing 211 . The urea water from the urea water supply module 420 is returned to the inside of the tank body 310 through the return pipe 232 by the pump device inside the urea water supply module 420 .

The urea water sender 200 includes a heating tube 240 as a part of a heating means for thawing the frozen urea water and preventing freezing of the urea water. The heating tube 240 is made of one tube, and is connected to the lower surface of the housing 211 at one end and the other end. One end of the heating pipe 240 communicates with the first pipe connector 221 through a fluid passage passing through the housing 211, and the other end of the heating pipe 240 communicates with the second fluid passage passing through the housing 211. It communicates with the pipe fitting 222. The heating tube 240 includes a pair of vertical portions 241 extending substantially vertically from the lower surface of the housing 211, and a vertical portion extending from one end of the vertical portion 241 to the end of the other vertical portion 241. 241 extends perpendicularly or parallel to the lower surface of the sender head 210 and includes a curved portion 242 curved in a C-shape or a U-shape. Cooling water from the internal combustion engine 10 flows into the heating pipe 240 from the cooling water supply pipe 471 through the first pipe connector 221 and then flows out again through the second pipe connector 222 . Freezing of the urea water in the tank body 310 may be prevented or the frozen urea water may be thawed by the cooling water of the internal combustion engine 10 passing through the inside of the heating pipe 240 . As another example of the heating tube 240, the heating tube 240 may include a coiled portion.

The urea count sender 200 has holders 251 and 252 for attaching the aforementioned sensors. The holders 251 and 252 are composed of an upper plate 251 and a lower plate 252 corresponding to the shape of the curved portion 242 of the heating pipe 240, and the upper plate 251 and the lower plate 252 are mutually connected by screw fastening. are combined The curved portion 242 of the heating tube 240 extends between the upper plate 251 and the lower plate 252 along their outer circumferences. The suction port located at the lower end of the suction pipe 231 is located between the upper plate 251 and the lower plate 252.

The urea water sender 200 includes a urea water level sensor 260 for measuring the level of the surface of the urea water stored in the tank body 310 . The urea level sensor 260 includes a guide tube 261 in which a plurality of reed switches are disposed therein along the longitudinal direction, and a float in which the guide tube 261 is inserted and includes a magnetic material and can float on the surface of the urea water (262). The guide tube 261 has one end attached to the lower surface of the housing 211, and the other end of the guide tube 261 is coupled to the holders 261 and 262. A signal from the reed switch inside the guide tube 261 is transmitted to the dosing control unit 440 via a circuit board in the housing 211 . The float 262 is movable up and down along the guide tube 261 . As the float 262 moves according to the change in the level of the urea water along the guide pipe 261, the level of the water surface of the urea water may be measured.

The urea water sender 200 includes a urea water temperature sensor (not shown) for measuring the temperature of the urea water in the tank body 310 . The urea water temperature sensor may be disposed at a height corresponding to the height of the suction port of the suction pipe 231 at the lower end of the guide pipe 261 of the urea water level sensor 260. The measurement signal of the urea water temperature sensor is transmitted to the dosing control unit 440 via the circuit board of the housing 211 . The dosing control unit 440 sends a signal to the engine control unit 11 of the internal combustion engine 10 when the temperature of the urea water drops below a predetermined value based on the measurement signal of the urea water temperature sensor, and the internal combustion engine 10 The engine control unit 11 of ) controls the internal combustion engine 10 to circulate the cooling water of the internal combustion engine 10 through the heating pipe 240 in response to a signal from the dosing control unit 440 .

The urea water sender 200 includes the urea concentration measuring device 100 according to the above-described embodiment to measure the urea concentration of the urea water in the tank body 310 . 2, 3, 17 and 18, the first and second brackets 131 and 132 of the urea concentration measuring device 100 are bolted to the lower plate 252 of the holder. Attached by fastening or screwing, the urea concentration measuring device 100 is positioned adjacent to the curved portion 242 of the heating tube 240 . An electric wire 116 extending from the ultrasonic transceiver 111 of the urea concentration measuring device 100 is connected to a circuit board inside the housing 211 . The measurement signal of the urea concentration measuring device 100 is transmitted to the dosing control unit 440 via the circuit board, and the dosing control unit 440 is a urea water supply module based on the measurement signal of the urea concentration measuring device 100. The urea water supply amount of the 420 and the urea water injection amount of the urea water injection module 430 are controlled.

The urea water sender 200 of the above-described embodiment includes the heating tube 240 for heating the urea water, but the urea water sender of another embodiment may not include the heating tube 240. In the urea number sender of this embodiment, the urea concentration measuring device 100 according to the embodiment may be attached using a support member to the suction pipe 231 or the like or attached to a holding member extending downward from the housing 211. In addition, the number of urea sender of another embodiment may not include the number of urea level sensor 260 or the number of urea temperature sensor.

The urea water tank 300 according to the embodiment shown in FIGS. 17 and 18 is equipped with the urea water sender 200 to which the urea concentration measuring device 100 of the above-described embodiment is attached. As another example, in the urea concentration measuring device 100 of the embodiment, the first bracket 131 and the second bracket 132 are coupled to the bottom wall 313 of the tank body 310 of the urea water tank 300. It can be mounted on the water tank 300.

The urea water tank 300 includes a tank body 310 for storing urea water. The upper wall 311 of the tank body 310 is formed with a mounting hole 315 in which the sender head 210 of the urea water sender 200 is mounted. The urea water sender 200 having the urea concentration measuring device 100 according to the embodiment is detachably fixed to the tank body 310 by combining the sender head 210 and the upper wall 311 of the tank body 310. do.

In addition, an inclined wall 314 is formed between the upper wall 311 and the side wall 312 of the tank body 310, and the inclined wall 314 has a mounting hole in which a plug 320 for urea water injection is mounted ( 316) is formed. The plug 320 is removably mounted in the mounting hole 316 . The inlet of the plug 320 can be opened and closed by the cap 321 . In addition, in the urea water tank 300, an indicator 330 for visually checking the level of the urea water in the tank body 310 is provided on the inclined wall 314 close to the upper wall 311 of the tank body 310. there is. The indicator 330 includes a transparent tube and a float disposed therein. The transparent tube of the indicator 330 communicates with the inside of the tank body 310 at its upper and lower ends. Accordingly, when the urea water is injected into the tank body 310 to a substantially full water level, the water level of the urea water may be visually confirmed through the float in the transparent tube.

In the urea concentration measuring apparatus 100 according to the above-described embodiment, the concentration measuring regions 113 and 113A, where ultrasonic waves propagate, are isolated from bubbles in the urea solution by the shielding members 140 , 140A and 140B. Therefore, the urea concentration measuring device 100 according to the embodiment can precisely measure the concentration of the urea solution without being affected by bubbles in the urea solution. In order to confirm the error measurement caused by bubbles in the urea solution and to check the performance of the urea concentration measuring device 100 according to the embodiment, the urea concentration measuring device of the comparative example and the urea concentration measuring device 100 of the embodiment were used. A number of densitometric tests were conducted. As the urea concentration measuring device of the comparative example used in the test, as shown in FIGS. 5 and 6, the shielding member 140 and the frame member 150 are removed from the urea concentration measuring device 100 according to the embodiment. has been used In the test, urea solution having a concentration of about 32.5 wt% was placed in a water tank, and the urea in the water tank was stirred to generate bubbles in the urea solution. The urea concentration measurement device of the Comparative Example was immersed in the bubble-containing urea solution, and the urea concentration was measured for about 20 minutes. In addition, the urea concentration measurement device 100 of the embodiment was immersed in the bubbled urea water, and the urea concentration was measured for about 20 minutes.

19 is a graph showing measured urea concentration values of the number of ureas measured by the urea concentration measuring device of the comparative example through the test. From FIG. 19 , the urea concentration measuring device of the comparative example without the shielding member 140 outputs a measured urea concentration ranging from about 22wt% to about 34wt%, even though the urea concentration of the urea water in the tank is unchanged. can know This is because bubbles in the urea solution invade the concentration measurement region 113 where the ultrasonic wave propagates, refracts or scatters the ultrasonic wave, and irregularly fluctuates the velocity and intensity of the ultrasonic wave. Figure 20 is a graph showing the measured value of the concentration of the number of urea measured by the urea concentration measuring device 100 of the embodiment through the test. From FIG. 20 , it can be seen that the urea concentration measuring device 100 of the embodiment continuously outputs a concentration measurement of about 32.5 wt% of urea. This is because the penetration of bubbles in the urea solution into the ultrasonic concentration measuring region is blocked by the shielding member 140 .

Hereinafter, an apparatus for measuring urea concentration including a shielding member having an air discharge hole as well as a plurality of through holes will be described.

21 is a perspective view illustrating a urea water sender having a urea concentration measuring device according to exemplary embodiments. 22 is a view showing the urea concentration measuring device of FIG. 21; 23 is a perspective view illustrating a shield member and a frame member of the urea concentration measuring device of FIG. 21; 24 is a side view illustrating the shield member and the frame member of FIG. 23; 25 is a bottom perspective view showing the shield member and the frame member of FIG. 23;

21 to 25, the urea concentration measuring device 100 is a concentration measuring device for measuring the urea concentration by detecting a wave propagating through the number of urea in the concentration measurement area (113, see FIG. 6), and the concentration measurement A shielding member 140 disposed to surround the area may be included. The concentration meter may include a transmitter for generating and transmitting the wave and a receiver for receiving the wave propagating through the number of elements in the concentration measurement area.

In exemplary embodiments, the concentration measuring device may be an ultrasonic concentration measuring device using ultrasonic waves. The ultrasonic concentration meter includes an ultrasonic transceiver (111, see FIG. 4) in which an ultrasonic transmitter and an ultrasonic receiver are integrated, and a reflector (112, see FIG. 5) that reflects ultrasonic waves transmitted by the ultrasonic transceiver 111 back to the ultrasonic transceiver. can include Alternatively, the ultrasound density meter may include an ultrasound transmitter 111T (see FIG. 16) and an ultrasound receiver 111R (see FIG. 16) spaced apart from each other in the traveling direction of the ultrasound waves.

The ultrasonic concentration meter may measure the urea concentration by detecting the velocity and intensity of ultrasonic wave propagating through the number of urea in the concentration measurement region between the ultrasonic transmitter and the ultrasonic receiver. Here, the concentration measurement region may be referred to as a space in which ultrasonic waves propagate through urea water between the ultrasonic transmitter and the ultrasonic receiver.

In example embodiments, the shielding member 140 may be disposed to surround part or all of the concentration measurement region. Since the shielding member 140 is coupled to the frame member 150, the concentration measurement area may be defined by the shielding member 140 between the ultrasound transceiver and the reflector. One shielding member may be coupled to surround a side surface of the frame member 150 . Alternatively, a plurality of shielding members may be combined to cover the plurality of openings 156 (see FIG. 8 ) of the frame member 150 .

The shielding member 140 may block air bubbles in the urea solution located outside the concentration measurement region from entering the concentration measurement region. The shielding member 140 may have a plurality of fine through holes 141 (see FIG. 9 ). The through hole 141 of the shielding member 140 may have a first size sufficient to block air bubbles.

For example, the first size of the through hole may be within a range of about 20 μm to about 200 μm. As shown in the graph of FIG. 29, when the size of the through hole is larger than 200 μm, the deviation of the measured value of urea concentration is 4% or more, and thus the measurement accuracy may be lowered. In addition, as shown in the graph of FIG. 30, when the size of the through hole is smaller than 20 μm, when the urea concentration is changed from 20% to 30%, for example, it takes to stabilize the measured value according to the concentration change. As the time increases, the responsiveness of the urea concentration measuring device may decrease.

In addition, the shielding member 140 may have at least one air discharge hole 146 or 148 for discharging air such as bubbles inside the concentration measurement region to the outside. The shielding member 140 may have an upper air discharge hole 146 and a lower air discharge hole 148 . The lower air discharge hole 148 facilitates the flow of urea water in the shielding member 140 so that air bubbles inside the concentration measurement area can be easily discharged through the upper air discharge hole 146 . Alternatively, the shielding member 140 may have only the upper air discharge hole 146 .

As shown in FIGS. 23 and 24 , two upper air discharge holes 146 and one lower air discharge hole 148 may be formed through the shield member 140 . The urea concentration measuring device 100 may have an overall height H from the bottom surfaces 158 and 159 of the first and second contact portions 151 and 152 . The position of the upper air discharge hole 146 may be disposed above the shield member 140 and the position of the lower air discharge hole 148 may be disposed below the shield member 140 . For example, the upper air discharge hole 146 may have a first height H1 from the bottom surface, and the lower air discharge hole 148 may have a second height H2 smaller than the first height from the bottom surface. there is. It will be understood that the number and location of the air discharge holes are not limited thereto.

As shown in FIGS. 23 to 25 , when the frame member has a triangular cylinder shape, the shield member 140 has a first side surface 145a facing upward, a second side surface 145b facing downward, and a side facing sideward. It may have a third aspect. The upper air discharge hole 146 may be formed through the first side surface 145a of the shield member 140, and the lower air discharge hole 148 may be formed through the second side surface 146b of the shield member 140. there is. An air discharge hole may not be formed on the third side surface of the shielding member 140 . The third side surface extends in a direction perpendicular to the installation surface of the urea concentration measuring device 100, the first side surface 145a extends upward at a predetermined angle with respect to the second side surface, and the second side surface 145b ) may extend downward at a predetermined angle toward the upper side with respect to the second side surface.

The air discharge holes 146 and 148 of the shielding member 140 may discharge air bubbles in the urea solution located inside the concentration measurement region to the outside of the concentration measurement region. The air discharge holes 146 and 148 may have a second size sufficient to discharge air bubbles. The second size of the air discharge hole may be greater than the first size of the through hole.

For example, the second size of the air discharge hole may be within a range of about 1.7 mm to about 4 mm. The second size of the air discharge hole may be determined in consideration of the size of air bubbles that may be generated inside the concentration measuring region. A minimum size of air bubbles that may be generated inside the concentration measurement region may be about 1.7 mm. As shown in the graph of FIG. 26 , when the size of the air discharge hole is smaller than 1.7 mm, the distribution of air in the concentration measuring area becomes 20% or more, and measurement accuracy may deteriorate. In addition, as shown in the graph of FIG. 28, when the size of the air discharge hole is larger than 4 mm, the deviation of the urea concentration measurement value is 4% or more, so measurement accuracy may be lowered.

The air discharge hole may have a triangular, quadrangular, rhombic, circular, or elliptical shape, but is not limited thereto. Regarding the shape of the air discharge hole, the size of the air discharge hole is the length of one side when the air discharge hole is triangular, the length of the diagonal when the air discharge hole is a square, rectangle or rhombus, and the air discharge hole. It may be defined as the length of the diameter when the air discharge hole is approximately circular, and the length of its major axis when the air discharge hole is approximately oval.

In example embodiments, the shielding member 140 may have an inner space extending in a vertical direction (gravity direction). The inner space may include the concentration measurement region and a bubble collection region connected to the concentration measurement region. The bubble collection area may be disposed in the direction of gravity from the concentration measurement area. Bubbles generated in the concentration measurement area may move to the bubble collecting area in the direction of gravity. The bubble collecting area may communicate with the upper air discharge hole. Accordingly, bubbles collected in the bubble collection area may be discharged to the outside of the shielding member 140 through the upper air discharge hole.

FIG. 26 is a graph showing the air distribution in the urea concentration measuring device according to the size of the air discharge hole measured using the urea concentration measuring device of FIG. 21 .

Referring to FIG. 26, according to the size of the air discharge hole, a distribution amount of air remaining without being discharged inside the concentration measuring area of the urea concentration measuring device of FIG. 21 was measured. It can be seen that as the size of the air discharge hole increases, the distribution amount of the non-exhausted air decreases. When the size of the air discharge hole is smaller than 1.7 mm, the distribution of air in the concentration measuring area becomes 20% or more, and thus measurement accuracy may deteriorate.

FIG. 27 is a graph showing air distribution in the urea concentration measuring device according to the presence or absence of a lower air discharge hole in the urea concentration measuring device of FIG. 21 .

Referring to FIG. 27, the distribution amount of air inside the concentration measuring region of the urea concentration measuring device of FIG. 21 was measured according to the presence or absence of the lower air discharge hole. It can be seen that when the lower air discharge hole is present, the distribution amount of the unexhausted air is reduced with respect to the same air discharge hole.

FIG. 28 is a graph showing the concentration measurement deviation according to the size of the air discharge hole measured using the urea concentration measuring device of FIG. 21 .

Referring to FIG. 28, the deviation of the measured urea concentration was measured according to the size of the air discharge hole. It can be seen that as the size of the air discharge hole increases, the deviation of the measured urea concentration increases. When the size of the air discharge hole is greater than 4 mm, the deviation of the measured value of the urea concentration may be 4% or more, and thus the measurement accuracy may be deteriorated.

FIG. 29 is a graph showing a concentration measurement deviation according to a size of a through hole measured using the urea concentration measuring device of FIG. 21 .

Referring to FIG. 29, the deviation of the measured urea concentration was measured according to the size of the through hole. It can be seen that the deviation of the urea concentration measurement value increases as the size of the through hole increases. When the size of the through hole is greater than 200 μm, the deviation of the measured value of the number of urea concentration may be 4% or more, and thus the measurement accuracy may be deteriorated.

FIG. 30 is a graph showing the stabilization time of the concentration change according to the size of the through hole measured using the urea concentration measuring device of FIG. 21 .

Referring to FIG. 30, the concentration change stabilization time was measured according to the size of the through hole. It can be seen that as the size of the through hole increases, the time required for stabilization according to the concentration change increases with the deviation of the urea concentration measurement value. When the size of the through hole is greater than 200 μm, the deviation of the measured value of the number of urea concentration may be 4% or more, and thus the measurement accuracy may be deteriorated.

The present invention described above is not limited by the above-described embodiments and accompanying drawings. It will be clear to those skilled in the art that various substitutions, modifications and changes are possible within the scope of the technical spirit of the present invention.

1010: internal combustion engine
100, 100A: urea concentration measuring device
111: ultrasonic transceiver
111T: ultrasonic transmitter
111R: ultrasonic receiver
112: reflector
113, 113A: concentration measurement area
120: spacer
130, 130A: support member
140, 140A, 140B: shielding member
141, 141A, 141B: through holes
146, 148: air discharge hole
150, 150A, 150B, 150C, 150D, 150E: frame member
200: Urea sender
210: sender head
211 housing
231: urea water suction pipe
232: urea water return pipe
240: heating tube
260: urea level sensor
300: urea water tank
310: tank body
400: selective catalytic reduction system
410: catalytic converter
420: urea solution supply module
430: urea solution injection module
440: dosing control unit

Claims (23)

A concentration meter immersed in urea water to measure urea concentration, and measuring the urea concentration by detecting a wave propagating through the urea water in a concentration measurement area between a transmitter and a receiver; and
A plurality of through holes disposed to surround the concentration measurement region and capable of preventing air bubbles in the urea solution from entering the concentration measurement region and at least one air exhaust for discharging bubbles inside the concentration measurement region to the outside. Urea concentration measuring device comprising a shielding member having a hole. The urea concentration measuring device according to claim 1, wherein the concentration measuring device comprises an ultrasonic concentration measuring device configured to measure the urea concentration by detecting ultrasonic waves propagating in the urea concentration measuring region. The ultrasonic concentration meter according to claim 2, wherein the ultrasonic concentration meter is an ultrasonic transceiver that transmits and receives the ultrasonic waves and a reflector that is spaced apart from the ultrasonic transceiver and reflects the ultrasonic waves to the ultrasonic transceiver, or an ultrasonic transmitter that transmits and receives the ultrasonic waves and the ultrasonic transmitter Urea concentration measuring device comprising an ultrasonic receiver spaced apart from and receiving the ultrasonic waves. The method of claim 1, further comprising a frame member coupled to the concentration meter and disposed in the concentration measurement region and having at least one opening,
The shielding member is coupled to the frame member so that at least a portion of the shielding member is positioned in the opening. The method of claim 4, wherein the frame member includes first contact portions and second contact portions positioned at both ends in a longitudinal direction, and holding portions disposed between the first contact portion and the second contact portion and having the openings for measuring urea concentration. Device. The urea concentration measuring device according to claim 4, wherein the side shape of the frame member has any one of a triangular shape, a rectangular shape, a circular shape, and a semicircular shape, or a combination of two or more of the triangular, rectangular, circular, and semicircular shapes. The method of claim 4, further comprising a spacer coupled to the ultrasonic transceiver and the reflector or the ultrasonic transmitter and the ultrasonic receiver of the concentration meter to separate them from each other,
The spacer is a urea concentration measuring device extending from the inside of the frame member. The method of claim 1, further comprising a support member for supporting the concentration meter,
The support member is a urea concentration measuring device coupled to a urea water sender or a urea water tank in which the urea concentration measuring device is located. The method of claim 8, wherein the support member
A first bracket for supporting the ultrasonic transceiver or ultrasonic transmitter of the concentration meter, and
Urea concentration measuring device comprising a second bracket for supporting the reflector or ultrasonic receiver of the concentration measuring device. The urea concentration measuring device according to claim 1, wherein the shield member includes any one of a mesh structure having the through hole, a thin film structure having the through hole, and a porous structure having the through hole. The urea concentration measuring device according to claim 10, wherein the size of the through hole is in the range of 20 μm to 200 μm. The urea concentration measuring device according to claim 1, wherein the air discharge hole has a size ranging from 1.7 mm to 4 mm. The urea concentration measuring device according to claim 1, wherein the air discharge hole includes an upper air discharge hole positioned above the shielding member. The urea concentration measuring device according to claim 13, wherein the air discharge hole further comprises a lower air discharge hole positioned below the shielding member. The method of claim 1, wherein the shielding member comprises a bubble collecting region connected to the concentration measuring region and disposed in a direction of gravity from the concentration measuring region, and bubbles generated in the concentration measuring region move to the bubble collecting region. Urea concentration measuring device. The urea concentration measuring device according to claim 15, wherein the air discharge hole communicates with the bubble collection area. A urea water sender mounted on a urea water tank for a selective catalytic reduction system,
A suction pipe through which urea water is sucked;
a return pipe through which the urea water is returned;
a heating tube for heating the urea water;
a holder coupled to the heating pipe; and
A urea concentration measuring device attached to the holder and measuring the urea concentration of the urea water,
The urea concentration measuring device,
An ultrasonic concentration meter immersed in the urea solution to measure the urea concentration, and measuring the urea concentration by detecting ultrasonic waves propagating through the urea solution in a concentration measurement area between an ultrasonic transmitter and an ultrasonic receiver; and
A plurality of through holes disposed to surround the concentration measuring region and preventing air bubbles in the urea solution from entering the concentration measuring region and at least one air discharge hole for discharging air bubbles inside the concentration measuring region to the outside Elemental water sender comprising a shielding member having. According to claim 17,
Further comprising a frame member coupled to the ultrasonic concentration meter by first and second brackets attached to the holder, disposed in the concentration measurement region, and having at least one opening;
The shielding member is coupled to the frame member so that at least a portion of the shielding member is positioned in the opening. According to claim 17, The size of the air discharge hole is urea water sender in the range of 1.7mm to 4mm. The urea concentration measuring device according to claim 17, wherein the size of the through hole is in the range of 20 μm to 200 μm. The urea water sender of claim 17, wherein the air discharge hole includes an upper air discharge hole positioned above the shielding member. The urea water sender of claim 21, wherein the air discharge hole further comprises a lower air discharge hole positioned under the shielding member. A urea water tank for storing urea water used in a selective catalytic reduction system, comprising the urea water sender according to claim 17.

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