JP2016211953A - Sensor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that suppresses detection errors possible to occur due to absorption of liquids by a holder to be arranged between electrodes.SOLUTION: A sensor device 60 comprises: electrodes 104 and 106 that oppose each other; and a holder 61 that supports the electrodes 104 and 106. The electrode 104 includes: a holding part 104S that is held by the holder 61; and an opposing part 104L that protrudes from the holder 61. The electrode 106 is held by the holder 61, and includes: a holding part 106S that is arranged across the holding part 104S and holder; and an opposing part 106L that protrudes from the holder 61, and opposes the opposing part 104L with a gap. The gap between the holding part 104S and the holding part 106S is greater than that between the opposing part 104L and the opposing part 104S.SELECTED DRAWING: Figure 2

Description

  In this specification, the sensor apparatus for detecting the property of a liquid is disclosed.

  Patent Document 1 discloses a fuel sensor. The fuel sensor includes an outer electrode and an inner electrode. Both the outer electrode and the inner electrode have a cylindrical shape. In the fuel sensor, fuel is caused to flow into the gap between the outer electrode and the inner electrode, and the ethanol concentration of the fuel is detected using the capacitance between the outer electrode and the inner electrode. That is, the ethanol concentration is detected using the dielectric constant of the fuel flowing into the gap between the outer electrode and the inner electrode. A part of the gap between the outer electrode and the inner electrode is filled with a resin holder that supports the outer electrode and the inner electrode. For this reason, the holder and the fuel exist in the gap between the outer electrode and the inner electrode.

JP 2012-108030 A

  The resin material absorbs the fuel. When the amount of fuel absorbed by the intervening portion of the holder located between the outer electrode and the inner electrode varies, the dielectric constant of the intervening portion varies. As a result, the capacitance between the outer electrode and the inner electrode varies depending on the amount of fuel absorbed by the intervening portion. Accordingly, an error occurs in the detection result of the ethanol concentration using the electrode.

  In this specification, the technique which can suppress the detection error which may arise when the holder arrange | positioned between electrodes absorbs a liquid is provided.

  In this specification, the sensor apparatus which detects the property of a liquid is disclosed. The sensor device includes a sensor having a first electrode and a second electrode facing each other, and a holder that supports the first electrode and the second electrode. The first electrode has a first grip portion gripped by the holder and a first facing portion protruding from the holder. The second electrode is gripped by the holder, protrudes from the holder with the first gripping portion and the second gripping portion disposed across the holder, and is opposed to the first facing portion with a gap therebetween. And an opposing portion. The distance between the first grip portion and the second grip portion is greater than the distance between the first facing portion and the second facing portion.

  In the above configuration, in the situation where the liquid exists between the first facing portion and the second facing portion, the property of the liquid is detected using the capacitance of the first electrode and the second electrode. The capacitances of the first electrode and the second electrode are determined by the capacitances of the first facing portion and the second facing portion and the capacitances of the first gripping portion and the second gripping portion. In said structure, the space | interval of a 1st holding part and a 2nd holding part is comparatively wide. According to this configuration, the capacitance of the first grip portion and the second grip portion can be made smaller than the capacitance of the first facing portion and the second facing portion. As a result, even if the relative permittivity of the holder fluctuates due to absorption of the liquid by the holder located between the first gripping portion and the second gripping portion, the electrostatic capacitance between the first electrode and the second electrode due to the variation. Capacitance fluctuation can be kept low. Thereby, the detection error by the liquid absorption of the holder arrange | positioned between electrodes can be suppressed.

  In the present specification, another sensor device for detecting the property of a liquid is disclosed. The sensor device includes a holder and a sensor having a first electrode and a second electrode facing each other. The first electrode has a first grip portion gripped by the holder and a first facing portion protruding from the holder. The second electrode is grasped by the holder and arranged between the first grasping portion and the intervening portion of the holder, and the second opposing portion that protrudes from the holder and faces the first facing portion with a gap And a portion. The interposition part is made of a material that does not absorb liquid.

  According to said structure, it can prevent that an interposition part absorbs a liquid. Thereby, it is possible to prevent the relative dielectric constant of the intervening portion from fluctuating. As a result, it is possible to control a detection error due to liquid absorption of the holder disposed between the electrodes.

The structure around the fuel tank of the first embodiment is shown. The structure of the liquid quality sensor of 1st Example is shown. The electrode of the III-III cross section of FIG. 2 is shown. The electrode of the IV-IV cross section of FIG. 2 is shown. The structure of the liquid quality sensor of 2nd Example is shown. Fig. 6 shows a VI-VI cross section of Fig. 5. The structure of the liquid quality sensor of 3rd Example is shown. The structure of the liquid quality sensor of 4th Example is shown.

  The main features of the embodiments described below are listed. The technical elements described below are independent technical elements and exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. Absent.

(Feature 1) In the sensor device, the first electrode may have a cylindrical shape. The second electrode may be disposed on the inner peripheral side of the first electrode. The outer peripheral surface of the second facing portion may have a cylindrical shape with a first radius that goes around the central axis of the first electrode. The outer peripheral surface of the second grip portion makes a round around the central axis of the first electrode, and may have a cylindrical shape with a second radius smaller than the first radius. According to this configuration, in a sensor device having a cylindrical electrode, a detection error due to liquid absorption of the holder can be suppressed.

(Feature 2) In the sensor device, the third radius of the inner peripheral surface of the first grip portion may be smaller than the fourth radius of the inner peripheral surface of the first opposing portion. The difference between the fourth radius and the third radius may be smaller than the difference between the first radius and the second radius. According to this structure, the 1st holding part of the 1st electrode located outside can be made small. As a result, the sensor device can be reduced in size.

(Feature 3) In the sensor device, the interposition part may be made of glass. According to this configuration, the intervening portion can be made of glass that hardly absorbs fuel.

(Feature 4) In the sensor device, the holder may have an outer peripheral wall that covers the entire outer peripheral surface of the first gripping portion. The holder may include an O-ring that goes around the outer periphery of the outer peripheral wall. Alternatively, the O-ring may be in contact with the outer peripheral surface of the first electrode. In the former configuration, the O-ring can be arranged at a position away from the electrode. According to this structure, it can suppress that an O-ring contacts the liquid which flows near the electrode.

(First embodiment)
The fuel supply unit 1 of this embodiment is mounted on an automobile and supplies fuel to an internal combustion engine (not shown). The fuel supply unit 1 includes a fuel tank 10, a fuel pump unit 30, and a sensor unit 2. The fuel tank 10 stores gasoline or a mixed fuel of gasoline and alcohol (for example, ethanol).

  The fuel pump unit 30 includes a low pressure filter 32, a pump main body 34, a high pressure filter 36, a reserve cup 20, a pressure regulator 42, and a discharge port 12. The low pressure filter 32, the pump main body 34, the high pressure filter 36, the reserve cup 20, and the pressure regulator 42 are disposed in the fuel tank 10. The pump main body 34 sucks the fuel in the reserve cup 20 from the suction port 34a of the pump main body 34 and raises the pressure. The pump body 34 discharges the pressurized fuel into the case 36a of the high-pressure filter 36 from the discharge port 34b.

  The low-pressure filter 32 is made into a bag shape with a nonwoven fabric. The inside of the low pressure filter 32 communicates with the suction port 34 a of the pump body 34. The high pressure filter 36 includes a case 36a and a filter member (not shown). Although simplified in FIG. 1, the case 36 a is disposed in the circumferential direction of the pump body 34. The fuel flowing into the case 36 a is filtered by the filter member of the high pressure filter 36 and sent out to the pipe 94. The fuel passes through the pipe 94 and is sent from the discharge port 12 to the internal combustion engine. The pipe 94 branches to the pipe 52 at an intermediate position. The pipe 52 extends to the sensor unit 2. A pressure regulator 42 is disposed at an intermediate position of the pipe 52. When the pressure of the fuel in the upstream portion 52a of the pipe 52 on the upstream side of the pressure regulator 42 becomes equal to or higher than the predetermined pressure, the pressure regulator 42 Release into the downstream portion 52b. Thereby, the pressure of the fuel in the upstream portion 52a, that is, the pressure of the fuel in the pipe 94 is adjusted to a constant pressure. The fuel in the fuel tank 10 is adjusted to a constant pressure by the pump body 34 and the pressure regulator 42 and is sent to the internal combustion engine.

  The pump main body 34, the high-pressure filter 36, and the low-pressure filter 32 are disposed in the reserve cup 20. The reserve cup 20 is fixed to the set plate 14 of the fuel tank 10 by a column 22. Fuel outside the reserve cup 20 is fed into the reserve cup 20 by a jet pump (not shown).

  The sensor unit 2 includes a control device 80 and a sensor device 60. The sensor unit 2 is fitted in the opening 14 a of the set plate 14. FIG. 2 is a longitudinal sectional view of the sensor device 60, that is, a sectional view of a cross section including a central axis of an electrode 104 described later. The same applies to FIGS. 5, 7 and 8. As shown in FIG. 2, the sensor device 60 includes a holder 61, an electrode pair 100, and a thermistor 108.

  The electrode pair 100 includes electrodes 104 and 106. Each of the electrodes 104 and 106 is made of a conductive material. The electrode 104 has a grip portion 104S and a facing portion 104L. The grip portion 104S has a cylindrical shape. The grip portion 104S is gripped by the holder 61. Both the inner peripheral surface and the outer peripheral surface of the grip portion 104S are covered with the holder 61 over the entire periphery. At the lower end of the grip portion 104S, a facing portion 104L is disposed continuously to the grip portion 104S in the depth direction (hereinafter referred to as “vertical direction”) of the fuel tank 10. The facing portion 104L has a cylindrical shape with the same inner diameter and outer diameter as the grip portion 104S. The central axes of the facing portion 104L and the gripping portion 104S are located on the same axis and are parallel to the vertical direction. The facing portion 104L extends downward from the lower end of the interposition portion 62 of the holder 61 described later. A communication port 104b that communicates the inside and the outside of the electrode 104 is disposed at the upper end of the facing portion 104L.

  The electrode 106 is disposed inside the electrode 104. The electrode 106 has a gripping portion 106S and a facing portion 106L. The grip portion 106S has a cylindrical shape having the same central axis X as the central axis of the grip portion 104S. The grip portion 106 </ b> S is gripped by the holder 61. Both the inner peripheral surface and the outer peripheral surface of the gripping portion 106S are covered with the holder 61 over the entire periphery. As shown in FIG. 4, the outer peripheral surface of the gripping portion 106S is opposed to the inner peripheral surface of the gripping portion 104S over the entire periphery. In FIG. 4, only the cross sections of the electrodes 104 and 106 are shown. The same applies to FIG.

  At the lower end of the gripping portion 106S, an opposing portion 106L is arranged continuously with the gripping portion 106S in the vertical direction. The facing portion 106L has a cylindrical shape having the same central axis as the central axis of the facing portion 104L. The facing portion 106L has the same plate thickness as the gripping portion 106S, and the inner diameter and the outer diameter of the facing portion 106L are larger than the inner diameter and the outer diameter of the gripping portion 106S, respectively. As shown in FIG. 3, the outer peripheral surface of the facing portion 106L is opposed to the inner peripheral surface of the facing portion 104L with a gap over the entire circumference.

  As shown in FIG. 3, the facing portion 106L has an outer peripheral surface with an outer diameter r1, and the facing portion 104L has an outer peripheral surface with an inner diameter r2. On the other hand, as shown in FIG. 4, the gripping portion 106S has an outer peripheral surface with an outer diameter r3 smaller than the outer diameter r1, and the gripping portion 104S has an outer peripheral surface with an inner diameter r4 equal to the inner diameter r2. As is apparent from comparison between FIGS. 3 and 4, the distance CS between the outer peripheral surface of the gripping portion 106S and the inner peripheral surface of the gripping portion 104S is between the outer peripheral surface of the facing portion 106L and the inner peripheral surface of the facing portion 104L. It is larger than the interval CL.

  As shown in FIG. 2, the electrode 106 is filled with a resin embedding portion 69 so that fuel does not enter inside. A thermistor 108 is disposed inside the electrode 106. The thermistor 108 is covered with resin. The thermistor 108 is disposed at the lower end of the electrode 106.

  The holder 61 includes an interposition part 62, a peripheral wall 64, a bottom wall 66, and a case 81. The holder 61 is made of a resin (for example, polyphenylene sulfide resin (that is, PPS)). The outer side of the electrode 104 is covered with a peripheral wall 64. The peripheral wall 64 has a cylindrical shape having the same central axis X as the central axis X of the electrode 104. The peripheral wall 64 extends upward from the same height as the lower end of the electrode 104. The upper end of the peripheral wall 64 is located above the upper end of the electrode 104. The peripheral wall 64 has a fuel flow path 115 extending parallel to the central axis X. The fuel flow path 115 is formed by denting a part of the inner peripheral side of the peripheral wall 64 to the outer peripheral side. The upper end of the fuel flow path 115 communicates with the communication port 104b. The lower end of the fuel flow path 115 reaches the lower end of the peripheral wall 64.

  An interposition part 62 is accommodated in the upper end part of the peripheral wall 64. The interposition part 62 is fitted to the inner periphery of the peripheral wall 64. The interposition part 62 has a cylindrical shape. A part of the lower end of the interposition part 62 is inserted between the electrodes 104 and 106. The electrode 104 is supported by gripping the grip portion 104 </ b> S between the peripheral wall 64 and the interposition portion 62. The electrode 106 is supported by inserting the gripping portion 106 </ b> S into the inner periphery of the interposition part 62. An embedded portion 69 is fixed on the inner peripheral side of the interposition portion 62.

  A bottom wall 66 is disposed at the lower end of the peripheral wall 64. The upper surface of the bottom wall 66 is in contact with the lower end of the electrode 104. The bottom wall 66 has a communication port 67 that penetrates the lower surface and the upper surface of the bottom wall 66 at the center. The communication port 67 is arranged coaxially with the electrode 106 and faces the lower end of the electrode 106. The communication port 67 communicates with the downstream portion 52b. Further, the bottom wall 66 has a communication port 68 passing through the lower surface and the upper surface of the bottom wall 66 between the electrode 104 and the electrode 106. The communication port 68 communicates with the fuel flow path 115.

  The storage space 110 is defined by the inner circumferential surface 104a of the facing portion 104L, the outer circumferential surface 106a of the facing portion 106L, the lower surface of the interposition portion 62, and the upper surface of the bottom wall 66. The lower end of the storage space 110 communicates with the pipe 52 through the communication port 67. The upper end of the storage space 110 communicates with the fuel flow path 115 through the communication port 104b. The lower end of the fuel flow path 115 communicates with the inside of the fuel tank 10 through the communication port 68.

  A case 81 is disposed at the upper end of the holder 61. The case 81 covers the outer peripheral surface of the peripheral wall 64 at the upper end of the peripheral wall 64. The case 81 is fitted into the opening 14 a of the set plate 14 via the O-ring 8. Above the O-ring 8, the set plate 14 and the case 81 are in direct contact over the entire circumference of the opening 14a.

  A control device 80 is disposed in the case 81. The control device 80 includes a control circuit 82 and an external terminal 84. The external terminal 84 supplies power to the control circuit 82. The control circuit 82 is mounted with a CPU, a memory, and the like. The control circuit 82 is a circuit for detecting the temperature of the fuel and the alcohol concentration using the sensor device 60.

(Operation of fuel supply unit 1)
When the driver starts the automobile, the fuel supply unit 1 is driven. As shown in FIG. 1, when the fuel supply unit 1 is driven, the fuel in the reserve cup 20 passes through the low pressure filter 32 and is sucked into the pump body 34. According to this configuration, the low pressure filter 32 can prevent foreign matter from entering the pump body 34. The fuel in the pump main body 34 is pressurized by the impeller in the pump main body 34 and discharged to the high-pressure filter 36 from the discharge port 34b. The fuel is filtered by the filter member of the high pressure filter 36 and sent out to the pipe 94. Fuel is supplied from the discharge port 12 to the internal combustion engine.

  The pressure regulator 42 releases the fuel released by the pressure regulation to the downstream portion 52b. As shown by the broken line arrow in FIG. 2, the fuel in the downstream portion 52 b flows into the storage space 110. The fuel that has flowed into the storage space 110 passes between the electrode 104 and the electrode 106 along the outer periphery of the electrode 106. The fuel flows from the lower side to the upper side in the storage space 110, passes through the communication port 104 b, and is discharged from the storage space 110 through the fuel flow path 115 into the fuel tank 10 from the communication port 68.

  While the fuel supply unit 1 is being driven, the control circuit 82 uses the sensor device 60 to detect the concentration of alcohol contained in the fuel. The control circuit 82 repeatedly detects the alcohol concentration until the automobile engine is stopped.

  Specifically, the control circuit 82 converts electric power supplied from a battery (not shown) into a signal or the like (eg, AC current) having a predetermined frequency (eg, 10 Hz to 3 MHz) and supplies the signal to the electrode 106. To do. The control circuit 82 is also connected to the electrode 104. The signal supplied to the electrode 106 returns from the electrode 104 to the control circuit 82. As a result, charges are accumulated in the electrode pair 100, and capacitance is generated. The control circuit 82 calculates the capacitance of the electrode pair 100 using the signal returned from the electrode 104 to the control circuit 82. Next, the control circuit 82 supplies DC power to the thermistor 108 via the conductor 86, and detects the temperature of the thermistor 108 from the resistance value of the thermistor 108. The temperature of the thermistor 108 is approximately equal to the temperature of the fuel in the storage space 110. For this reason, the control circuit 82 can detect the temperature of the fuel in the storage space 110 by detecting the temperature of the thermistor 108.

  In the electrode pair 100, the fuel is filled between the facing portions 104L and 106L. For this reason, the electrostatic capacitance of the electrode pair 100 varies in correlation with the dielectric constant of the fuel. Since the dielectric constant of gasoline and the dielectric constant of alcohol differ greatly, the dielectric constant of fuel changes with the alcohol concentration. Further, the dielectric constant of the fuel varies in correlation with the temperature of the fuel. The control circuit 82 uses a signal supplied to the electrode 106 to specify a circuit for specifying the capacitance of the electrode pair 100, and for converting the specified capacitance into a fuel dielectric constant. The circuit is implemented. The control circuit 82 stores a database for calculating the alcohol concentration in the fuel from the dielectric constant of the fuel and the temperature of the fuel. The database is specified in advance by experiment or analysis. When the control circuit 82 acquires the signal returned from the electrode 104 to the control circuit 82, the control circuit 82 refers to the database and detects the alcohol concentration in the fuel from the dielectric constant of the fuel. The control circuit 82 outputs the detected alcohol concentration to an ECU (abbreviation of Engine Control Unit). The ECU adjusts the amount of fuel supplied to the engine according to the alcohol concentration in the fuel.

(Effect of this embodiment)
In the above configuration, the alcohol concentration is detected using the capacitance of the electrode pair 100. The capacitance of the electrode pair 100 is the sum of the capacitance of the facing portions 104L and 106L and the capacitance of the grip portions 104S and 106S. The electrostatic capacitances of the facing portions 104L and 106L vary depending on the relative dielectric constant of the fuel. On the other hand, the electrostatic capacitances of the grip portions 104S and 106S vary depending on the relative dielectric constant of the interposition portion 62 disposed between the grip portions 104S and 106S.

  The relative dielectric constant of the interposition part 62 varies depending on the amount of fuel absorbed by the interposition part 62 and the relative dielectric constant of the fuel. Since the storage space 110 is filled with fuel, the fuel contacts the interposition part 62 that defines the storage space 110. Since the interposition part 62 is made of resin, the interposition part 62 absorbs fuel. As a result, the relative dielectric constant of the interposition part 62 varies according to the amount of fuel absorbed by the interposition part 62 and the relative dielectric constant of the fuel.

  The capacitance of the electrode pair is proportional to S / d, where d is the distance between the electrodes and S is the opposing area of the electrodes. That is, the capacitance is reduced by increasing the distance between the electrodes. In the above configuration, the interval CS between the gripping portions 104S and 106S is larger than the interval CL between the opposing portions 104L and 106L. For this reason, the electrostatic capacitances of the gripping portions 104S and 106S can be made smaller than the electrostatic capacitances of the opposing portions 104L and 106L. Thereby, the influence of the fluctuation | variation of the electrostatic capacitance of the holding parts 104S and 106S which acts on the electrostatic capacitance of the electrode pair 100 can be suppressed. It is possible to control a detection error of the sensor device 60 due to a change in dielectric constant due to fuel absorption of the interposition part 62.

  Further, the vertical lengths of the gripping portions 104S and 106S are shorter than the lengths of the opposing portions 104L and 106L in the central axis direction. Thereby, the facing area of the gripping portions 104S and 106S can be made smaller than the facing area of the facing portions 104L and 106L. Thereby, the electrostatic capacitance of the gripping portions 104S and 106S can be made smaller than the electrostatic capacitance of the facing portions 104L and 106L.

(Second embodiment)
Differences from the first embodiment will be described with reference to FIGS. The sensor device 60 of the second embodiment has an electrode 204 instead of the electrode 104. The electrode 204 has a gripping portion 204S and a facing portion 204L. The facing portion 204L has the same configuration as the facing portion 104L. The gripping portion 204S has a cylindrical shape having the same central axis as the central axis of the facing portion 204L. Both the inner peripheral surface and the outer peripheral surface of the gripping portion 204S are covered with the holder 61 over the entire periphery. An opposing portion 204L is continuously arranged at the lower end of the grip portion 204S. The gripping portion 204S has the same thickness as that of the facing portion 204L, and the inner diameter and the outer diameter of the gripping portion 204S are smaller than the inner diameter and the outer diameter of the facing portion 204L, respectively. As apparent from comparison between FIG. 3 and FIG. 6, the difference between the inner diameter r2 of the facing portion 204L and the inner diameter r5 of the gripping portion 204S is greater than the difference between the outer diameter r1 of the facing portion 106L and the outer diameter r3 of the gripping portion 106S. Is also small. For this reason, the distance CS2 between the gripping part 106S and the gripping part 204S is larger than the distance CL between the facing part 106L and the facing part 104L.

  According to this configuration, as in the first embodiment, the electrostatic capacities of the gripping portions 204S and 106S can be made smaller than the electrostatic capacities of the facing portions 204L and 106L. Thereby, the influence of the fluctuation | variation of the electrostatic capacitance of the holding parts 204S and 106S which acts on the electrostatic capacitance of the electrode pair 100 can be suppressed. Thereby, it is possible to control the detection error of the sensor device 60 due to the variation of the dielectric constant due to the fuel absorption of the interposition part 62.

  The peripheral wall 64 has a shape that follows the outer shape of the electrode 204. For this reason, the outer diameter of the peripheral wall 64 and the case 81 that cover the outer peripheral surface of the grip portion 204S can be reduced. Thereby, the contact area of the set plate 14 and the holder 61 can be reduced. As a result, fuel can be prevented from leaking from between the set plate 14 and the holder 61. Moreover, the force by the pressure which the holder 61 receives from the fuel in the fuel tank 10 can be suppressed.

(Third embodiment)
Differences from the first embodiment will be described with reference to FIG. The sensor device 60 according to the present embodiment includes an electrode 306 instead of the electrode 106. Further, the sensor device 60 of the present embodiment includes a holder 361 instead of the holder 61. Further, the sensor device 60 according to the present embodiment includes an accommodation wall 364 instead of the peripheral wall 64 and the bottom wall 66.

  The housing wall 364 is formed integrally with the set plate 14. The housing wall 364 covers the outer peripheral surface of the electrode 104. The housing wall 364 is made of the same material as the set plate 14 (for example, a non-conductive material such as resin). The housing wall 364 has a bottomed cylindrical shape having the same central axis as the central axis of the electrode 104. The lower end of the storage wall 364 is positioned at the same height as the lower end of the electrode 104, and the upper end of the storage wall 364 is positioned below the upper end of the electrode 104.

  The holder 361 is located above the accommodation wall 364. The holder 361 includes an interposition part 362a and a case 381. The case 381 is in contact with the upper end of the accommodation wall 364. The case 381 is fitted over the opening 14 a of the set plate 14 via the O-ring 8 above the accommodation wall 364. A control device 80 is disposed in the case 381. The case 381 covers the outer periphery of the grip portion 104S of the electrode 104.

  The electrode 306 has a gripping portion 306S and a facing portion 306L. The grip portion 306S has a cylindrical shape. An opposing portion 306L is continuously arranged at the lower end of the grip portion 306S. The facing portion 306L has a cylindrical shape having the same inner diameter and outer diameter as the grip portion 306S. The central axes of the facing portion 306L and the gripping portion 306S are located on the same axis and are parallel to the depth direction of the fuel tank 10.

  The outer peripheral surface of the gripping portion 306S is covered with the interposition part 362a. The interposition part 362a is made of glass. The interposition part 362a is formed by pouring molten glass between the electrodes 306 and 104 and solidifying it. The interposition part 362a is located between the inner peripheral surface of the grip portion 104S and the outer peripheral surface of the grip portion 306S. The interposition part 362a is made of glass that does not absorb fuel. For this reason, the dielectric constant of the interposition part 362a does not fluctuate by fuel absorption. For this reason, the electrostatic capacitance between the gripping portion 306S and the gripping portion 104S does not vary greatly. Thereby, the detection error of the sensor device 60 due to the variation of the dielectric constant due to the fuel absorption of the interposition part 362a can be controlled.

  The O-ring 8 is disposed on the outer peripheral side of the case 381. According to this configuration, the fuel in the storage space 110 can be prevented from coming into contact with the O-ring 8. Thereby, it can suppress that O-ring 8 deteriorates by contacting a fuel.

(Fourth embodiment)
Differences from the third embodiment will be described with reference to FIG. In the sensor device 60 of the present embodiment, the case 381 is located above the O-ring 8. That is, the O-ring 8 is in direct contact with the outer peripheral surface of the grip portion 104S of the electrode 104.

  As mentioned above, although embodiment of this invention was described in detail, these are only illustrations and do not limit a claim. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.

(Modification)
(1) In the above embodiment, the sensor device 60 detects the alcohol concentration in the fuel. However, the sensor device 60 may detect the degree of fuel deterioration (for example, the degree of fuel oxidation), the liquid level of the fuel, and the like.

(2) The “sensor device” may be used to detect liquids other than fuel, for example, properties of cooling water (for example, the degree of deterioration, the type of cooling water, and the liquid level).

(3) In each of the above embodiments, the pipe 52 is connected to the pressure regulator 42. However, the pipe 52 may be branched from the pipe 94 or connected to the vapor jet of the pump body 34.

(4) In each of the above embodiments, the number of electrodes of the sensor device 60 and the like is not limited to two. However, the sensor device 60 may include three or more electrodes.

(5) In each of the above embodiments, the control circuit 82 detects the alcohol concentration or the like using the capacitance of each electrode pair, that is, the dielectric constant of the fuel. However, the control circuit 82 may detect the alcohol concentration by using a value obtained by using an electrode pair other than the capacitance of the electrode pair, for example, the conductivity of the fuel obtained by using the electrode pair. .

(6) In each of the above embodiments, the electrode 104 or the like has a cylindrical shape. However, the shape of the electrode 104 or the like is not limited to a cylindrical shape. For example, the electrode 104 may be a polygonal cylinder such as an ellipse or a rectangle, or may be a plate shape such as a flat plate. Further, for example, the electrode 106 may have a cylindrical shape, a cylindrical shape having a hollow inside, a cylindrical shape such as an ellipse or a quadrangle, or a column shape. Note that, regardless of whether the electrode 106 is cylindrical, columnar, or partially hollow, the outer peripheral surface of the electrode 106 can be said to be cylindrical.

  The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology illustrated in the present specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

1: fuel supply unit, 2: sensor unit, 10: fuel tank, 20: reserve cup, 30: fuel pump unit, 42: pressure regulator, 52: pipe, 60: sensor device, 61: holder, 62: interposition part, 81: case, 100: electrode pair, 104: electrode, 104L: facing portion, 104S: gripping portion, 104a: inner peripheral surface, 104b: communication port, 106: electrode, 106L: facing portion, 106S: gripping portion, 106a: Outer peripheral surface, 108: thermistor, 110: storage space

Claims (6)

A sensor device for detecting the properties of a liquid,
A sensor having a first electrode and a second electrode facing each other;
A holder for supporting the first electrode and the second electrode,
The first electrode is
A first gripping part gripped by the holder;
A first opposing portion protruding from the holder,
The second electrode is
A second gripping part which is gripped by the holder, and is arranged with the first gripping part sandwiched between the holders;
Projecting from the holder, and having a second opposing portion facing the first opposing portion with an interval,
The sensor device, wherein an interval between the first grip portion and the second grip portion is larger than an interval between the first opposing portion and the second opposing portion. The first electrode has a cylindrical shape,
The second electrode is disposed on the inner peripheral side of the first electrode,
The outer peripheral surface of the second facing portion has a cylindrical shape with a first radius that goes around the central axis of the first electrode,
2. The sensor device according to claim 1, wherein an outer peripheral surface of the second gripping portion makes a round around the central axis of the first electrode and has a cylindrical shape with a second radius smaller than the first radius. The third radius of the inner peripheral surface of the first grip portion is smaller than the fourth radius of the inner peripheral surface of the first opposing portion,
The sensor device according to claim 2, wherein a difference between the fourth radius and the third radius is smaller than a difference between the first radius and the second radius. A sensor device for detecting the properties of a liquid,
A holder,
A sensor having a first electrode and a second electrode facing each other,
The first electrode is
A first gripping part gripped by the holder;
A first opposing portion protruding from the holder,
The second electrode is
A second gripping part which is gripped by the holder and is disposed with the first gripping part and the interposition part of the holder interposed therebetween;
A second opposing portion that protrudes from the holder and faces the first opposing portion with an interval,
The said interposition part is a sensor apparatus produced with the material which does not absorb the said liquid.   The sensor device according to claim 4, wherein the interposition part is made of glass. The holder has an outer peripheral wall covering the outer peripheral surface of the first grip portion over the entire circumference,
The sensor device according to claim 4, wherein the holder includes an O-ring that makes a round of the outer periphery of the outer peripheral wall.

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