JP2015017857A - Flow rate sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow rate sensor in which positioning accuracy of a sensor chip relative to a flow channel can be enhanced and the influence of heat of a circuit chip on the sensor chip can be reduced.SOLUTION: A sensor assembly 21 has a lead frame 25 on which a circuit chip 23 is mounted, a body 26 partially sealing the circuit chip 23 and the lead frame 25, and a projecting part 27 to which a sensor chip 22 is fixed and which projects from the body 26. The lead frame 25 has an exposure part 40 where a part of the lead frame 25 is exposed from a tip part 39 of the projecting part 27. The exposure part 40 is fixed by being inserted into a groove part 17 formed in an opposing part 16 which, out of a flow channel 11 of a flow channel part 10, opposes the projecting part 27. In this way, not only the position of the projecting part 27 is fixed but also heat of the sensor assembly 21 is transmitted to the opposing part 16.

Description

  The present invention relates to a flow sensor for detecting a flow rate of a fluid.

  Conventionally, for example, Patent Document 1 proposes a flow rate measuring device that detects the flow rate of a fluid flowing through a tubular body. Specifically, the flow measurement device includes a sensor body having a sensor chip that senses a flow rate and a circuit chip that processes a signal of the sensor chip.

  The sensor body has a cantilever structure with a part protruding. The sensor chip is fixed to the protruding portion, and the protruding portion and the sensor chip are positioned in the bypass passage by fixing the sensor body to the bypass passage (flow path) provided in the pipe body. Yes. Thereby, the flow rate of the fluid passing through the bypass passage is detected by the sensor chip.

JP 2003-194599 A

  However, the conventional technology has a problem in that the position of the sensor chip cannot be accurately determined because the protruding portion of the sensor body protrudes from the wall surface of the bypass passage into the flow path. In addition, since heat during operation of the circuit chip is transmitted to the sensor chip through the sensor body, there is no escape path for the heat, so that the sensor chip is affected by the heat. For this reason, there exists a problem of affecting the measurement precision of a sensor chip.

  An object of the present invention is to provide a flow sensor capable of improving the accuracy of positioning of a sensor chip with respect to a flow path and reducing the influence of heat of a circuit chip on the sensor chip.

  In order to achieve the above object, according to the first aspect of the present invention, the sensor has a sensing unit (33) for detecting the flow rate of the fluid, and outputs a flow rate signal corresponding to the flow rate detected by the sensing unit (33). A chip (22) is provided, and a circuit chip (23) for inputting a flow rate signal and performing predetermined signal processing is provided.

  In addition, the main body (26) in which the circuit chip (23) is sealed, and the sensor chip (22) is fixed so that the sensing section (33) is exposed, and the protruding portion (from the main body (26) ( 27) and a sensor assembly (21).

  Moreover, it has the flow path (11) through which the fluid passes, and the protruding part (27) of the sensor assembly (21) protrudes into the flow path (11) and the sensing part (33) of the sensor chip (22). Is provided with a flow path portion (10) for holding the sensor assembly (21) such that the sensor assembly (21) is positioned in the flow path (11).

  Furthermore, fixing means (17, 19, 40, 42) for fixing the tip (39) of the protruding portion (27) to the facing portion (16) of the flow path (11) facing the protruding portion (27). It is characterized by having.

  According to this, the protruding portion (27) of the sensor assembly (21) is fixed at a predetermined position in the flow path (11) by the fixing means (17, 19, 40, 42). The positioning accuracy of the sensing unit (33) can be improved. Further, even if the heat generated in the circuit chip (23) is transferred to the sensor chip (22) side through the sensor assembly (21), the heat flows through the fixing means (17, 19, 40, 42). It is transmitted to the opposing part (16) of (11). Therefore, the influence of the heat of the circuit chip (23) on the sensor chip (22) can be reduced.

  In addition, the code | symbol in the bracket | parenthesis of each means described in this column and the claim shows the correspondence with the specific means as described in embodiment mentioned later.

It is a partial sectional view of a flow sensor concerning a 1st embodiment of the present invention. It is II-II sectional drawing of FIG. It is a top view of a sensor part. It is IV-IV sectional drawing of FIG. It is a top view of the sensor part concerning a 2nd embodiment of the present invention. FIG. 6 is a partial cross-sectional view of a flow rate sensor in which the sensor unit shown in FIG. 5 is fixed to a flow path unit. It is a partial cross section figure of the flow sensor concerning a 3rd embodiment of the present invention. It is VIII-VIII sectional drawing of FIG. It is a partial cross section figure of the flow sensor concerning a 4th embodiment of the present invention. It is XX sectional drawing of FIG. It is a partial cross section figure of the flow sensor concerning a 5th embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals in the drawings.

(First embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1 and FIG. 2, the flow sensor includes a flow path unit 10 and a sensor unit 20.

  The flow path unit 10 is a component having a flow path 11 through which a fluid passes. In the present embodiment, the flow path 11 includes a linear first passage 12 that takes in fluid from the outside and discharges the fluid to the outside, and is branched from the first passage 12 and is circular (spiral or donut-shaped) first. 2 passages 13.

  Moreover, the flow path part 10 has the hole 14 for discharging | emitting the fluid which passed the 2nd channel | path 13 outside. Thereby, the fluid that has passed through the second passage 13 is discharged to the outside of the flow path portion 10 via the first passage 12 or the hole portion 14. The flow path unit 10 is fixed to, for example, an intake manifold of a vehicle.

  As shown in FIGS. 3 and 4, the sensor unit 20 is configured to detect the flow rate of fluid, and includes a sensor assembly 21, a sensor chip 22, a circuit chip 23, and a sealing material 24. And a lead frame 25.

  The sensor assembly 21 is a base body of the sensor unit 20, and includes a main body part 26 and a protruding part 27. The main body 26 is a portion where a part of the lead frame 25 and a part of the circuit chip 23 are sealed. The protruding portion 27 protrudes from the main body portion 26 and has a concave portion 28, and the sensor chip 22 is disposed in the concave portion 28. The sensor assembly 21 is formed by molding, for example, PPS (polyphenylene sulfide) or epoxy resin.

  As shown in FIG. 4, the sensor chip 22 includes a front surface 29, a back surface 30 opposite to the front surface 29, and a membrane 31 that is thinned because a part of the back surface 30 is recessed toward the front surface 29. It is a plate-like semiconductor chip. Further, the sensor chip 22 is fixed to the concave portion 28 of the protruding portion 27 with an adhesive 32 so that the back surface 30 is directed toward the concave portion 28 and the sensing portion 33 is exposed.

  On the membrane 31, a heater resistor (not shown) or a resistor (temperature measuring resistor) different from the heater resistor is formed. The resistance temperature detector includes a resistance for monitoring the heat generation temperature of the heater and a resistance for detecting the temperature upstream and downstream of the heater resistance. The heat generation temperature of the heater resistor is controlled to be a constant heat generation temperature by the monitor resistance. Further, a bridge circuit is configured by temperature measuring resistors respectively arranged upstream and downstream of the heater resistance, and the output of the bridge circuit changes due to the temperature difference between the upstream and downstream of the heater resistance, and the flow rate of the fluid flowing above the membrane 31 Is to be detected. In the sensor chip 22, the part where the bridge circuit is formed corresponds to the sensing unit 33 that detects the flow rate of the fluid. The sensor chip 22 outputs a flow rate signal corresponding to the flow rate detected by the sensing unit 33.

  The circuit chip 23 is formed with a control circuit or the like having a function of outputting a drive signal to the sensor chip 22, inputting a flow rate signal from the sensor chip 22, performing calculation / amplification processing and outputting the same to the outside. It is a thing. Such a circuit chip 23 is a semiconductor chip in which, for example, a CMOS transistor or the like is formed by a semiconductor process on a silicon substrate or the like. The circuit chip 23 is electrically connected to the sensor chip 22 via a wire 34. The wires 34 are bonded to pads (not shown) provided on the circuit chip 23 and the sensor chip 22, respectively.

  The sealing material 24 is a resin member that protects the wire 34 and the connecting portion of the wire 34. The sealing material 24 seals a part of the sensor chip 22, a part of the circuit chip 23, the wire 34, and the like so that the membrane 31 of the sensor chip 22 is exposed. The sealing material 24 is disposed in a region surrounded by a U-shape in the main body portion 26 of the sensor assembly 21 and is provided on the surface 29 of the sensor chip 22 so as not to flow toward the sensing portion 33 side. It is stopped at 35. For example, an epoxy resin is employed as the sealing material 24.

  The lead frame 25 is a metal terminal component for electrically connecting the circuit chip 23 and the outside. Specifically, the lead frame 25 has a plurality of terminal portions 36 and island portions 37.

  The plurality of terminal portions 36 are insert-molded in the main body portion 26 of the sensor assembly 21 so as to be partially exposed. Further, as shown in FIG. 3, the plurality of terminal portions 36 are arranged in a direction perpendicular to the longitudinal direction of the terminal portions 36. The pads of the circuit chip 23 and the corresponding terminal portions 36 are connected by wires 38, respectively. Thereby, the circuit chip 23 and each terminal part 36 are electrically connected.

  The island part 37 is a plate-like part on which the circuit chip 23 is mounted. The island part 37 is sealed by the sensor assembly 21 so that a part of the island part 37 opposite to the terminal part 36 is exposed from the protruding part 27. The “part of the island portion 37” is the exposed portion 40 that protrudes from the tip portion 39 of the protruding portion 27 and is exposed. The exposed portion 40 is a fixing means for fixing the position of the protruding portion 27 of the sensor assembly 21 to the flow path portion 10.

  The sensor unit 20 having the above configuration is fixed to the flow path unit 10. Specifically, as shown in FIG. 1 and FIG. 2, the flow path part 10 has the insertion hole 15 for arranging the sensor part 20 so that the sensing part 33 of the sensor part 20 is located in the second passage 13. have. The sensor assembly 20 is inserted into the insertion hole 15 so that the protruding portion 27 of the sensor assembly 21 protrudes into the second passage 13 and the sensing portion 33 of the sensor chip 22 is positioned in the second passage 13. 21 is held in the flow path section 10.

  Further, the flow path portion 10 has a facing portion 16 that opposes the protruding portion 27 of the sensor assembly 21 in the flow path 11. In the present embodiment, the facing portion 16 constitutes a part of the second passage 13. That is, since the second passage 13 is circular, it can be said that the portion on the center side of the circle is the facing portion 16.

  The facing portion 16 has a slit-like groove portion 17 into which the exposed portion 40 of the lead frame 25 is inserted. Therefore, when the sensor unit 20 is inserted into the insertion hole 15 of the flow path unit 10, the exposed portion 40 of the lead frame 25 is inserted into the groove portion 17 of the facing portion 16. At this time, the exposed portion 40 is inserted into the groove portion 17 until the distal end portion 39 of the protruding portion 27 of the sensor portion 20 contacts the facing portion 16. In this way, the protruding portion 27 of the sensor unit 20 is fixed to the facing portion 16 of the flow path portion 10 by the exposed portion 40.

  The above is the configuration of the flow sensor according to the present embodiment. In the flow rate sensor, the circuit chip 23 energizes the heater resistance of the sensor chip 22 according to a command from the outside and heats it. Then, since the midpoint potential difference of the bridge circuit changes according to the flow rate, the midpoint potential difference (flow rate signal) is signal-processed by the circuit chip 23 and output to the outside. The external device that has acquired the flow signal acquires fluid flow data based on the flow signal.

  Next, the effect of the structure of the flow sensor will be described. In the present embodiment, the protruding portion 27 of the sensor assembly 21 is fixed to the facing portion 16 of the flow path portion 10 by the exposed portion 40. For this reason, since the position of the protruding portion 27 is reliably fixed without being affected by the fluid, the positioning accuracy of the sensing portion 33 with respect to the flow path 11 can be improved. Further, when the fluid passes through the second passage 13, the protruding portion 27 of the sensor unit 20 can be prevented from being shaken by the fluid.

  On the other hand, heat generated by the operation of the circuit chip 23 is transmitted to the sensor chip 22 side via the lead frame 25 and the sensor assembly 21. However, this heat is transmitted to the facing portion 16 of the flow path 11 through the exposed portion 40, and an escape path for the heat transmitted to the sensor chip 22 side is secured. Therefore, the influence of the heat of the circuit chip 23 on the sensor chip 22 can be reduced. Here, the heat transmitted through the lead frame 25 is directly transmitted to the facing portion 16 through the exposed portion 40, so that the heat can be actively released to the facing portion 16. For this reason, the heat dissipation of the sensor assembly 21 can be improved.

  In particular, in the present embodiment, the exposed portion 40 is inserted into the groove portion 17 so that the distal end portion 39 of the protruding portion 27 contacts the facing portion 16. For this reason, since the protrusion part 27 is fixed to the opposing part 16 reliably, the positioning precision of the sensing part 33 with respect to the flow path 11 can be improved. Moreover, since the contact area of the protrusion part 27 with respect to the opposing part 16 can be ensured, the heat dissipation of the sensor assembly 21 can be improved.

  In the structure of the flow sensor shown in FIGS. 1 and 2, a resin forming portion (not shown) may be formed so as to cover the sensor portion 20. As for the correspondence between the description of the present embodiment and the description of the claims, the groove portion 17 and the exposed portion 40 of the facing portion 16 correspond to “fixing means” in the claims.

(Second Embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIG. 5, in the present embodiment, the lead frame 25 has a heat radiating portion 41. The heat dissipating part 41 is provided in a part of the island part 37 of the lead frame 25 located at the protruding part 27 of the sensor assembly 21.

  Further, the heat radiating portion 41 is exposed from the protruding portion 27 in a direction parallel to the surface direction of the surface 29 of the sensor chip 22 and inclined with respect to the protruding direction of the protruding portion 27 with respect to the flow path 11. Yes. In the present embodiment, the “tilted direction” is a direction perpendicular to the protruding direction. Further, the heat radiating portion 41 protrudes and is exposed from the protruding portion 27 in both directions perpendicular to the protruding direction so as to be located on both the upstream side and the downstream side of the fluid.

  As shown in FIG. 6, when the sensor unit 20 is fixed to the flow path unit 10, the heat radiating unit 41 is exposed to the second passage 13. For this reason, when a fluid flows through the second passage 13, the fluid takes away heat from the heat radiating unit 41. Therefore, the heat dissipation of the sensor assembly 21 can be further enhanced. In this embodiment, since the heat radiating part 41 is exposed in both directions perpendicular to the protruding direction, the flow of fluid to the sensing part 33 is not affected.

(Third embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIGS. 7 and 8, in the present embodiment, the facing portion 16 has a fin 18 made of metal such as Al or Cu inside. The fin 18 is insert-molded in the facing portion 16 when the flow path portion 10 is formed.

  Specifically, the fin 18 is not exposed to the second passage 13 as shown in FIG. 7, but a part of the fin 18 is exposed from the wall surface of the flow path unit 10 as shown in FIG. 8. . The fin 18 is also formed with a part of the groove portion 17 into which the exposed portion 40 is inserted.

  When the exposed portion 40 of the lead frame 25 is inserted into the groove portion 17 of the facing portion 16, the exposed portion 40 contacts the fin 18. Accordingly, since the heat of the circuit chip 23 is transmitted to the fins 18 through the lead frame 25, the heat of the circuit chip 23 can be easily released. Further, heat radiation can be enhanced by a portion of the fin 18 exposed from the flow path portion 10.

(Fourth embodiment)
In the present embodiment, parts different from the first embodiment will be described. As shown in FIGS. 9 and 10, in the present embodiment, the facing portion 16 itself is configured as a metal fin such as Al or Cu. In the present embodiment, as shown in FIG. 10, the fins 18 are insert-molded in the flow path portion 10. A part of the facing portion 16 is exposed from the wall surface of the flow path portion 10.

  Further, a groove portion 17 into which the exposed portion 40 is inserted is also formed in the facing portion 16. Therefore, when the exposed portion 40 of the lead frame 25 is inserted into the groove portion 17 of the facing portion 16, the exposed portion 40 contacts the metal facing portion 16.

  As described above, since the facing portion 16 itself is made of metal, the heat of the circuit chip 23 can be easily released to the facing portion 16. Moreover, since the fluid contacts the facing portion 16 and deprives the heat of the facing portion 16, the heat dissipation effect can be further enhanced.

(Fifth embodiment)
In the present embodiment, parts different from the first to fourth embodiments will be described. The present embodiment is characterized in that a fixing means for fixing the protruding portion 27 of the sensor unit 20 is provided in the facing portion 16.

  As shown in FIG. 11, the facing portion 16 has a protruding portion 19 in which a part of the facing portion 16 protrudes toward the protruding portion 27. The protruding portion 19 is a fixing means for fixing the protruding portion 27 to the facing portion 16. On the other hand, the protruding portion 27 has a groove-like insertion portion 42 into which the protruding portion 19 is inserted while being recessed toward the main body portion 26 side of the sensor portion 20 in a portion corresponding to the protruding portion 19 in the distal end portion 39.

  According to the above configuration, the heat of the circuit chip 23 is transmitted to the facing portion 16 via the sensor assembly 21 and the protruding portion 19, so that the heat can be actively released to the facing portion 16. Therefore, the heat dissipation of the sensor assembly 21 can be improved even in the structure in which the fixing means is provided in the facing portion 16.

  As for the correspondence between the description of this embodiment and the description of the claims, the insertion portion 42 and the protrusion 19 of the protrusion 27 correspond to the “fixing means” of the claims.

(Other embodiments)
The configuration of the flow sensor shown in each of the above embodiments is an example, and is not limited to the configuration shown above, and may be another configuration that can realize the present invention. For example, the flow path 11 of the flow path portion 10 has the first passage 12 and the second passage 13, but the flow passage portion 10 may be composed of only the linear first passage 12, It may be configured only by the second passage 13. Moreover, you may be comprised by another path | route. Regardless of the route through which the fluid passes, the portion of the route that faces the protruding portion 27 of the sensor unit 20 becomes the facing portion 16.

  In 1st-4th embodiment, although the case where the planar shape of the exposed part 40 is a square shape is shown, this is an example of the planar shape of the exposed part 40. Therefore, other planar shapes may be used.

  The shape of the heat radiation part 41 shown in the second embodiment is an example. For example, the heat radiating part 41 may be provided only on one of the upstream side and the downstream side of the fluid. Further, the planar shape of the heat radiating portion 41 may be different from the shapes shown in FIGS. 5 and 6.

  In the third embodiment, the fin 18 is insert-molded in the facing portion 16 so as to be exposed on the wall surface of the flow path portion 10, but the fin 18 is not exposed from the wall surface of the flow path portion 10 and is inside the facing portion 16. It may be sealed. Similarly, in the fourth embodiment, the facing portion 16 that is a fin may be insert-molded in the flow channel portion 10 without being exposed from the wall surface of the flow channel portion 10.

  The facing portion 16 according to the fifth embodiment may have the fins 18 as in the third embodiment. Moreover, the opposing part 16 which concerns on 5th Embodiment may comprise the opposing part 16 itself with a metal fin similarly to 4th Embodiment. Of course, the heat radiation part 41 shown in the second embodiment may be employed in the flow sensor according to the fifth embodiment.

  In each of the above embodiments, the tip portion 39 of the protruding portion 27 of the sensor unit 20 is in contact with the facing portion 16, but the tip portion 39 may not be in contact with the facing portion 16. Even in this case, the exposed portion 40 is fixed to the facing portion 16. Further, the protruding portion 19 is fixed to the insertion portion 42.

  And a flow sensor is not restricted to a vehicle, It can fix to the other channel | path through which a fluid passes. Thereby, the flow rate of the fluid can be measured.

10 channel portion 11 channel 16 facing portion 17 groove portion (fixing means)
DESCRIPTION OF SYMBOLS 21 Sensor assembly 22 Sensor chip 23 Circuit chip 26 Main body part 27 Protruding part 33 Sensing part 39 Tip part 40 Exposed part (fixing means)

Claims (7)

A sensor chip (22) having a sensing unit (33) for detecting the flow rate of the fluid, and outputting a flow rate signal corresponding to the flow rate detected by the sensing unit (33);
A circuit chip (23) for inputting the flow rate signal and performing predetermined signal processing;
A main body part (26) encapsulating the circuit chip (23) and a protrusion protruding from the main body part (26) while the sensor chip (22) is fixed so that the sensing part (33) is exposed. A sensor assembly (21) having a portion (27);
A flow path (11) through which the fluid passes, and the protruding portion (27) of the sensor assembly (21) protrudes into the flow path (11) and the sensing portion of the sensor chip (22); A flow path portion (10) for holding the sensor assembly (21) such that (33) is positioned in the flow path (11);
Fixing means (17, 19, 40, 42) for fixing the tip (39) of the protruding portion (27) to the facing portion (16) of the flow path (11) facing the protruding portion (27). When,
A flow sensor comprising: The sensor assembly (21) is covered with the sensor assembly (21) and has a metal lead frame (25) on which the circuit chip (23) is mounted.
The fixing means is an exposed portion (40) in which a part of the lead frame (25) is exposed from a tip portion (39) of the protruding portion (27),
The flow sensor according to claim 1, wherein the facing portion (16) has a groove portion (17) into which the exposed portion (40) of the lead frame (25) is inserted.   The lead frame (25) is parallel to the surface direction of the surface (29) of the sensor chip (22) and is inclined with respect to the protruding direction of the protruding portion (27) with respect to the flow path (11). The flow rate sensor according to claim 2, further comprising a heat dissipating part (41) exposed from the protruding part (27) in a given direction.   The said opposing part (16) has a metal fin (18) which the exposed part (40) of the said lead frame (25) contacts inside, The Claim 2 or 3 characterized by the above-mentioned. Flow sensor.   The flow sensor according to claim 2 or 3, wherein the facing portion (16) is configured as a metal fin that contacts the exposed portion (40) of the lead frame (25). The fixing means is a protruding portion (19) in which a part of the facing portion (16) protrudes from the facing portion (16) toward the protruding portion (27).
The flow rate sensor according to claim 1, wherein the protruding portion (27) has an insertion portion (42) into which the protruding portion (19) is inserted.   The protruding portion (27) is fixed to the facing portion (16) by the fixing means (17, 19, 40, 42) so that the tip portion (39) contacts the facing portion (16). The flow sensor according to any one of claims 1 to 6, wherein the flow sensor is provided.

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