JP2010223687A - Liquid density detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid density detector for detecting the density of a liquid to be detected with high precision. <P>SOLUTION: A spherical float 20 is housed in the internal space 13 of the holding number 10 attached to a fuel pipe 60 storing fuel. The buoyancy of the float 20 is detected by a pressure sensor 30, and an tilt angle detection means 40 detects the tilt angle tilted with respect to a vertical direction of the pressure sensor 30. An electrical circuit 50 corrects the buoyancy detection value P detected by the pressure sensor 30 on the basis of the output of the tilt angle detected by the tilt angle detection means to detect the value corresponding to the density of the liquid to be detected. The friction force between the float 20 and the inner wall of the holding member 10 becomes small enough to neglect by the tumbling motion of the float 20 on the inner wall of the holding member 10. By this constitution, the pressure sensor 30 accurately detects the pressing force of the float. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a liquid density detection device that detects the density of a liquid.

  2. Description of the Related Art Conventionally, a liquid density detection device that detects the density of a liquid by detecting buoyancy received by a float immersed in the liquid is known (see Patent Document 1). In this liquid density detection device, a float is accommodated inside a cylindrical holding member, and the buoyancy of the float is detected by a pressure sensor. Then, the liquid density detection device calculates the density of the liquid in which the float is immersed based on the buoyancy detection value detected by the pressure sensor and the volume and density of the float stored in advance.

Japanese Patent No. 3946301

However, in this type of liquid density detection device, when the holding member is tilted, the pressure sensor cannot accurately detect the buoyancy of the float due to the frictional force between the inner wall of the holding member and the float, and the detection error increases. There was a problem.
The present invention has been made in view of the above-described problems, and an object thereof is to provide a liquid density detection device that detects the density of a liquid to be detected with high accuracy.

  According to the first aspect of the invention, the spherical float is accommodated in the internal space of the holding member that is filled with the liquid to be detected. The inclination angle detection means detects an inclination angle at which the pressure sensor for detecting the buoyancy of the float is inclined with respect to the vertical direction. The calculation unit detects the density equivalent value of the liquid to be detected by correcting the buoyancy detection value detected by the pressure sensor based on the tilt angle output detected by the tilt angle detection means. When the spherical float rolls on the inner wall of the holding member, the frictional force between the float and the inner wall of the holding member is reduced to a negligible level, and the pressure sensor can accurately detect the float buoyancy detection value. it can. If this liquid density detector is attached to the fuel system piping of the engine, the volatility of the fuel for automobiles and the fuel density have a correlation, so the volatility of the fuel is determined by the fuel density equivalent value detected by the liquid density detector. It is possible to accurately detect and perform optimal engine control according to the volatility of the fuel.

  In this specification, the pipe to which the cylindrical holding member is attached includes a flow pipe that fills the liquid to be detected, a pipe that holds the liquid to be detected, a container, and the like, and the holding member is configured integrally with the pipe. Also good. In addition, the spherical float includes not only a circular shape in cross section but also an elliptical shape.

  According to the second aspect of the present invention, the holding member includes the cylindrical portion whose inner wall is formed in a cylindrical shape, and a lid portion that closes one end of the cylindrical portion on the outside air side and to which the pressure sensor is attached. For this reason, the outer wall of the float contacts the inner wall of the cylindrical portion and the pressure sensor at only one point. Thereby, the pressure sensor can accurately detect the buoyancy of the float.

  According to the invention which concerns on Claim 3, the cylindrical part and the cover part are integrally formed. For this reason, while improving the sealing performance of the connection part of a cylindrical part and a cover part, the manufacturing cost of a holding member can be reduced.

  According to the invention of claim 4, the float is hollow inside. Thereby, the buoyancy of the float can be adapted to the detection capability of the pressure sensor, and the detection accuracy of the pressure sensor can be improved.

  According to the invention which concerns on Claim 5, a holding member has a through-hole through which the to-be-detected liquid distribute | circulates to the radial direction of a cylindrical part. For this reason, for example, when a liquid density detection device is attached to a fuel pipe of an automobile and the density of the fuel is detected as the liquid to be detected, the liquid density detection device can quickly detect a change in the density of the fuel in the fuel pipe. .

  According to the invention of claim 6, the inclination angle detecting means is formed in a bottomed cylindrical shape, and the outer wall has a spherical first bottom portion and a cylindrical first cylindrical portion connected to the first bottom portion. An electrode, an inner electrode provided on the inner side of the outer electrode without contact with the inner wall of the outer electrode, a liquid dielectric that contacts the inner wall of the outer electrode and the outer wall of the inner electrode, and the outer electrode and the inner electrode. A detecting unit that electrically connects and calculates an inclination angle of the pressure sensor by detecting a capacitance between the outer electrode and the inner electrode; With this configuration, the tilt angle detecting means can detect tilts in all directions. For this reason, if this liquid density detection device is applied to a fuel system or the like of an automobile that may tilt in all directions, the fuel density is accurately detected and optimal engine control according to the volatility of the fuel is performed. be able to.

  According to the invention of claim 7, the inner electrode is formed in a bottomed cylindrical shape, and has an outer wall having a spherical second bottom portion and a cylindrical second tube portion connected to the second bottom portion. For this reason, the contact area between the outer electrode and the dielectric changes according to the tilt angle, and the contact area between the inner electrode and the dielectric changes. Thereby, the electrostatic capacitance which a detection part detects changes a lot according to an inclination angle. Therefore, the calculation unit can calculate the inclination angle of the holding member with high accuracy.

  According to the eighth aspect of the invention, the inner wall of the first tube portion of the outer electrode is connected in the tangential direction of the spherical surface of the inner wall of the first bottom portion. According to the invention described in claim 9, the outer wall of the second tube portion of the inner electrode is connected in the tangential direction of the spherical surface of the outer wall of the second bottom portion. As a result, the dielectric moves smoothly along the inner wall of the outer electrode or the outer wall of the inner electrode. Therefore, the inclination angle detection means can improve the response of the capacitance change detected by the detection unit.

  According to the invention of claim 10, when the axial direction of the outer electrode is the vertical direction, the position where the dielectric and the inner wall of the outer electrode are in contact is the connection position between the first bottom portion and the first tube portion. According to the invention of claim 11, when the axial direction of the inner electrode is a vertical direction, the position where the dielectric and the outer wall of the inner electrode are in contact is the connection position between the second bottom portion and the second tube portion. is there. For this reason, even when the axial direction of the outer electrode or the inner electrode is slightly inclined from the vertical direction, the area where the outer electrode or the inner electrode contacts the dielectric changes. Thereby, the detection part can calculate the inclination-angle of a holding member with high precision.

  In the invention according to claim 6 described above, the tilt angle detecting means can be grasped as an invention of a tilt angle detecting device for detecting the tilt angle with high accuracy. That is, “an outer electrode having a bottomed cylindrical shape with an inner wall having a spherical bottom surface and a cylindrical first tube portion connected to the first bottom portion; An inner electrode provided in non-contact with the inner wall, a liquid dielectric in contact with the inner wall of the outer electrode and the outer wall of the inner electrode, and electrically connected to the outer electrode and the inner electrode, the outer electrode and the inner electrode, An inclination angle detection apparatus comprising: a detection unit that calculates an inclination angle of at least one of the outer electrode and the inner electrode by detecting a capacitance between the electrodes. " With this configuration, it is possible to detect an inclination in any direction of 360 ° on a plane perpendicular to the axial direction of the outer electrode or the inner electrode. You may apply the invention of Claim 7-11 to this inclination-angle detection apparatus.

The block diagram which shows the liquid density detection apparatus of 1st Embodiment of this invention. The block diagram which shows the inclination-angle detection means of the liquid density detection apparatus of 1st Embodiment of this invention. The block diagram which shows the liquid density detection apparatus of 2nd Embodiment of this invention. The block diagram which shows the liquid density detection apparatus of 3rd Embodiment of this invention.

Hereinafter, a plurality of embodiments according to the present invention will be described with reference to the drawings. The first embodiment embodies the features of the inventions of claims 1, 2 and 6-11, and the second embodiment embodies the features of the inventions of claims 3-5. .
(First Embodiment)
The liquid density detection apparatus according to the first embodiment of the present invention is applied to an engine fuel system, and detects the density of fuel as a liquid to be detected. The fuel density detected by the liquid density detection device is transmitted to an on-vehicle ECU (engine control unit). The ECU calculates the volatility of the fuel from the density of the fuel, and performs engine control according to the volatility of the fuel.

As shown in FIG. 1, the liquid density detection device 1 includes a holding member 10 fixed to a fuel pipe 60, a float 20, a pressure sensor 30, an inclination angle detection unit 40, and the like.
The holding member 10 is formed in a cylindrical shape from a material having a small coefficient of friction, such as resin or metal, and has a cylindrical portion 11 whose inner wall is cylindrical, and a disc-shaped lid portion that closes one end of the cylindrical portion 11 on the outside air side. 12. The holding member 10 is provided on the outer wall of the fuel pipe 60 connecting the engine and the fuel tank so as to go straight in the fuel flow direction. The holding member 10 is attached at least partially in the fuel pipe 60 so that the fuel flowing through the fuel pipe 60 flows into the holding member 10, and the other end of the cylindrical portion 11 is opened in the fuel pipe 60. Yes.
The outer wall in the radially outward direction of the lid portion 12 and the inner wall of the cylindrical portion 11 are sealed in a liquid-tight manner. For this reason, leakage of fuel from the connecting portion between the lid portion 12 and the cylindrical portion 11 to the outside is prevented, and outside air is prevented from entering the holding member 10.

  The float 20 is formed in a solid or spherical shape from a material having a density lower than that of the fuel, such as a synthetic resin or a foamed resin. The float 20 has rigidity that is not deformed by the fuel pressure, and comes into contact with the inner wall of the cylindrical portion 11 at only one point. The diameter of the float 20 is formed smaller than the inner diameter of the cylindrical portion 11, and when the axial direction of the cylindrical portion 11 is inclined with respect to the vertical direction, the inner space 13 is rotated and moved upward in the vertical direction.

  The pressure sensor 30 is, for example, an electronic pressure sensor, and is provided on the inner space 13 side of the lid portion 12. The pressure sensor 30 is attached perpendicular to the axial direction of the cylindrical portion 11. Since the pressure sensor 30 detects buoyancy in the plate thickness direction, the direction in which the pressure sensor 30 detects buoyancy is the axial direction of the holding member 10. Therefore, when the holding member 10 is inclined, the detected buoyancy value of the float 20 detected by the pressure sensor 30 is a component force in the axial direction of the holding member 10 out of the buoyancy that the float 20 receives from the fuel.

As shown in FIGS. 1 and 2, the tilt angle detection means 40 is composed of an outer electrode 41, an inner electrode 44, and a dielectric 47, and one end in the axial direction is inserted into the fuel pipe 60 in the vicinity of the holding member 10. Yes.
The outer electrode 41 is formed in a bottomed cylindrical shape, and includes a first bottom portion 42 having an inner wall formed in a hemispherical shape, and a cylindrical first tube portion 43. The inner diameter of the first cylinder portion 43 and the inner diameter of the first bottom portion 42 are formed to have the same size. The inner wall of the first cylindrical portion 43 is connected to the tangential direction of the spherical inner wall of the first bottom portion 42, and the first cylindrical portion 43 and the first bottom portion 42 are integrally formed.
The outer electrode 41 is attached to the fuel pipe 60 so that the axial direction of the first cylinder portion 43 and the axial direction of the cylindrical portion 11 of the holding member 10 are the same direction. For this reason, the inclination angle at which the axial direction of the first cylindrical portion 43 is inclined with respect to the vertical direction is an inclination angle at which the pressure sensor 30 is inclined with respect to the vertical direction. Therefore, the tilt angle detection means 40 can detect the tilt angle of the pressure sensor 30 by detecting the tilt angle of the first tube portion 43.

The inner electrode 44 is formed in a bottomed cylindrical shape, and has a second bottom portion 45 having an inner wall formed in a hemispherical shape, and a cylindrical second cylindrical portion 46. The outer diameter of the second cylindrical portion 46 and the outer diameter of the second bottom portion are formed to have the same size. The outer wall of the second cylindrical portion 46 is connected to the tangential direction of the spherical outer wall of the second bottom portion 42, and the second bottom portion 45 and the second cylindrical portion 46 are integrally formed.
The inner electrode 44 is provided on the inner side of the outer electrode 41 in a non-contact manner with the inner wall of the outer electrode 41. The distance between the inner wall of the outer electrode 41 and the outer wall of the inner electrode 44 is the same in all directions. A broken line 48 shown in FIG. 1 conceptually shows a connection surface between the first bottom portion 42 and the first tube portion 43 and a connection surface between the second bottom portion 45 and the second tube portion 46. The outer electrode 41 and the inner electrode 44 are assembled so that the connection surface between the first bottom portion 42 and the first tube portion 43 and the connection surface between the second bottom portion 45 and the second tube portion 46 are in the same plane. ing.

The dielectric 47 is a liquid nonconductor having a large relative dielectric constant and a small change in viscosity due to a temperature change, and is placed between the inner wall of the outer electrode 41 and the outer wall of the inner electrode 44. When the axial direction of the outer electrode 41 and the inner electrode 44 is in the vertical direction, the dielectric 47 and the inner wall of the outer electrode 41 and the outer wall of the inner electrode 44 are in contact at a position indicated by a broken line 48.
The dielectric 47 changes the area in contact with the inner wall of the outer electrode 41 and the area in contact with the outer wall of the inner electrode 44 according to the inclination angle of the outer electrode 41 and the inner electrode 44. Thereby, the inclination angle detection means 40 can detect the inclination angles in all directions.

  The electric circuit 50 is composed of electric elements such as a microcomputer, an IC, and a resistor. The electric circuit 50 is electrically connected to the pressure sensor 30 by wirings 51 and 52, and is electrically connected to the outer electrode 41 and inner electrode 44 by wirings 53 and 54. The electric circuit 50 is electrically connected to an ECU (not shown) or the like.

The electric circuit 50 detects the fuel density in the internal space of the holding member 10 from the buoyancy detection value of the float 20 detected by the pressure sensor 30, the tilt angle output detected by the tilt angle detection means 40, and the volume and density of the float 20.
Here, the buoyancy F received by the float 20 from the fuel in the internal space 13 of the holding member 10, the float buoyancy detection value P detected by the pressure sensor 30, the tilt angle θ that the pressure sensor 30 tilts with respect to the vertical direction, and the float 20. The relationship between the volume V, the fuel density md of the internal space 13 of the holding member 10, and the density mf of the float 20 is
P = Fcosθ
Since F = V (md−mf),
P = V (md−mf) cos θ... Formula (1)
It becomes. The electric circuit 50 detects a value corresponding to the fuel density mf from the equation (1).

The electric circuit 50 transmits the fuel density equivalent value to the ECU. Here, a fuel with a high fuel density has a high volatility because it has many heavy components, and a fuel with a low fuel density has a high volatility because there are many light components. For this reason, the ECU can control the engine such as the injection amount and the ignition timing according to the volatility of the fuel by detecting the volatility of the fuel from the fuel density equivalent value.
The electric circuit 50 functions as a “detection unit” described in the claims by detecting the inclination angle θ from the capacitance detected by the inclination angle detection means 40, and the inclination angle θ and the pressure sensor 30 By detecting a value corresponding to the fuel density mf from the detected buoyancy detection value P and the volume V and density md of the float 20, it functions as an “arithmetic unit” described in the claims.

  In the present embodiment, the float 20 is formed in a spherical shape. For this reason, the frictional force between the float 20 and the inner wall of the holding member 10 becomes small enough to be ignored, and the pressure sensor 30 can accurately detect the buoyancy detection value of the float 20. Further, since the inclination angle detection means 40 detects the inclination angle θ with respect to the vertical direction of the pressure sensor 30, the electric circuit 50 detects the buoyancy detection value P of the float 20 detected by the pressure sensor 30, the inclination angle θ, and the volume of the float 20. The value corresponding to the fuel density mf in the fuel pipe 60 can be accurately detected based on V and the density md.

  Furthermore, in the present embodiment, the inner wall of the first bottom portion 42 of the outer electrode 41 and the outer wall of the second bottom portion 45 of the inner electrode 44 are formed in a hemispherical shape. The inner wall of the first cylindrical portion 43 is connected in the tangential direction of the inner wall of the first bottom portion 42, and the outer wall of the second cylindrical portion 46 is connected in the tangential direction of the outer wall of the second bottom portion 45. For this reason, the inclination angle detection means 40 can detect any inclination in any direction of 360 ° on a plane perpendicular to the axial direction of the outer electrode and the inner electrode, and is capable of detecting a change in the attitude of the vehicle. Since the body 47 moves smoothly, the response of detecting the tilt angle can be improved. Thus, the liquid density detection device 1 accurately detects the density of the fuel in the fuel pipe 60 and transmits it to the ECU, so that the ECU can perform optimal engine control according to the volatility of the fuel. . Therefore, the vehicle to which the liquid density detection device 1 is applied can obtain the optimum driving performance according to the fuel.

(Second Embodiment)
Next, a liquid density detection apparatus according to the second embodiment will be described with reference to FIG. Hereinafter, in the plurality of embodiments, the same reference numerals are given to substantially the same configurations as those in the first embodiment, and the description thereof is omitted. In the liquid density detection device 2 of the present embodiment, the cylindrical portion 71 and the lid portion 72 of the holding member 70 are integrally formed. Thereby, the sealing performance of the connecting portion between the cylindrical portion 71 and the lid portion 72 is improved, and the manufacturing cost is reduced.
Further, through holes 73 and 74 are formed in the radially outward direction of the cylindrical portion 71, and the fuel in the fuel pipe 60 flows into the internal space of the holding member 70 through the through holes 73 and 74.

  The float 80 is formed in a spherical shape from a hard material such as ceramic or metal. The float 80 has an inside 81 that is hollow. Inside the float 80, air of a predetermined atmospheric pressure is enclosed so that the buoyancy received by the float from the fuel matches the detection pressure range of the pressure sensor 30.

In this embodiment, the density of the float 80 can be relatively reduced by using the float 80 in which the inside 81 is formed hollow. As a result, the amount of change in the buoyancy detection value of the float 80 detected by the pressure sensor 30 increases corresponding to the inclination angle of the holding member 70. For this reason, the pressure sensor 30 can accurately detect the buoyancy of the float 80. Therefore, the liquid density detection device 2 can accurately detect the fuel density.
Further, in the present embodiment, through holes 73 and 74 are formed in the radially outward direction of the cylindrical portion 71. Accordingly, since the fuel in the internal space 13 of the holding member 70 is quickly replaced in response to the change in the fuel density in the fuel pipe 60, the liquid density detection device 2 promptly changes the density of the fuel in the fuel pipe 60. Can be detected.

(Third embodiment)
Next, a liquid density detection device according to a third embodiment will be described with reference to FIG. In the liquid density detection device 3 of this embodiment, the cross section of the float 90 is formed in an elliptical shape. Even in such a configuration, when the axial direction of the cylindrical portion 11 is inclined with respect to the vertical direction, the float 90 is made small enough to ignore the frictional force between the inner wall of the holding member 10 and the outer wall of the float 90. The internal space 13 is moved upward in the vertical direction. For this reason, the liquid density detection device 3 can accurately detect the fuel density.

(Other embodiments)
In the above-described embodiments, the liquid density device applied to the fuel pipe of the engine has been described. On the other hand, the liquid density detection device of the present invention is not limited to engine fuel, and may be applied to a device that detects the density of various liquids to be detected.
In the plurality of embodiments described above, the holding member and the inclination angle detecting means are provided in the vicinity of the fuel pipe. On the other hand, in the liquid density detection device of the present invention, the holding member and the inclination angle detection means may be provided integrally.
In the plurality of embodiments described above, the electric circuit is provided separately from the holding member and the inclination angle detecting means. On the other hand, in the liquid density detection device of the present invention, the electric circuit may be provided integrally with the holding member and the inclination angle detection means.
In the plurality of embodiments described above, the first bottom portion and the second bottom portion of the tilt angle detecting means are formed in a hemispherical shape. On the other hand, the first bottom portion and the second bottom portion of the tilt angle detecting means of the present invention are not limited to a hemispherical shape, and may have a shape having an opening in a part of a sphere.
Furthermore, the present invention can be used as an inclination angle detection device that detects the inclination angle of various articles with high accuracy by using only the inclination angle detection means of the present invention. Further, the density of the liquid to be detected may be detected only by removing the tilt angle detection means from the liquid density detection device.
Thus, the liquid density detection apparatus of the present invention is not limited to the above-described embodiment, and can be applied as various embodiments.

  1: liquid density detection device, 10: holding member, 13: internal space, 20: float, 30: pressure sensor, 40: inclination angle detection means, 50: electric circuit (calculation unit, detection unit), 60: fuel piping ( Piping)

Claims (11)

Piping for storing the liquid to be detected in the internal space;
A cylindrical holding member disposed in the pipe;
A spherical float that is housed in the internal space of the holding member and has a lower density than the liquid to be detected;
A pressure sensor for detecting the buoyancy of the float;
An inclination angle detecting means for detecting an inclination angle at which the pressure sensor is inclined with respect to a vertical direction;
A liquid comprising: an arithmetic unit that detects a density equivalent value of a liquid to be detected by correcting a buoyancy detection value detected by the pressure sensor based on an inclination angle output detected by the inclination angle detection unit. Density detector.   The said holding member is provided with the cylindrical part in which an inner wall is formed in a cylindrical shape, and the cover part which obstruct | occludes the one end by the side of the outside air of this cylindrical part, and attaches the said pressure sensor. Liquid density detector.   The liquid density detection device according to claim 2, wherein the cylindrical portion and the lid portion are integrally formed.   The liquid density detecting device according to claim 1, wherein the float has a hollow inside.   5. The liquid density detection device according to claim 2, wherein the holding member has a through hole through which a liquid to be detected flows in a radial direction of the cylindrical portion. The inclination angle detecting means includes
An outer electrode having a cylindrical shape with a bottom and an inner wall having a spherical first bottom and a cylindrical first cylindrical portion connected to the first bottom;
An inner electrode provided in non-contact with the inner wall of the outer electrode on the inner diameter side of the outer electrode;
A liquid dielectric in contact with the inner wall of the outer electrode and the outer wall of the inner electrode;
A detection unit that is electrically connected to the outer electrode and the inner electrode and detects an inclination angle of the pressure sensor by detecting a capacitance between the outer electrode and the inner electrode. The liquid density detection apparatus according to claim 1, wherein the liquid density detection apparatus is a liquid density detection apparatus.   The liquid according to claim 6, wherein the inner electrode is formed in a bottomed cylindrical shape, and the outer wall includes a spherical second bottom portion and a cylindrical second cylindrical portion connected to the second bottom portion. Density detector.   8. The liquid density detection device according to claim 6, wherein an inner wall of the first cylindrical portion of the outer electrode is connected in a tangential direction of a spherical surface of the inner wall of the first bottom portion.   9. The liquid density detection according to claim 6, wherein an outer wall of the second cylindrical portion of the inner electrode is connected in a tangential direction of a spherical surface of the outer wall of the second bottom portion. apparatus.   When the axial direction of the outer electrode is a vertical direction, a position where the dielectric and the inner wall of the outer electrode are in contact is a connection position between the first bottom portion and the first tube portion. The liquid density detection apparatus as described in any one of Claims 6-9.   When the axial direction of the inner electrode is a vertical direction, a position where the dielectric and the outer wall of the inner electrode are in contact is a connection position between the second bottom portion and the second tube portion. The liquid density detection apparatus as described in any one of Claims 6 to 10.

Images