JP3743558B2 - Oil detection device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an oil detection device that detects the degree of deterioration of oil.
[0002]
[Prior art]
As oil for hydraulic control or lubrication used in vehicles or the like is used, foreign matter is mixed in or changes with time, so that the PH value indicating acidity or alkalinity changes. A change in the PH value indicates that the oil has deteriorated. Therefore, it is important to detect the degree of oil deterioration and know the oil replacement time. An oil detection device that detects the degree of deterioration of oil includes a reference electrode having a substantially constant potential regardless of the PH value of oil and a comparison electrode in which the potential changes depending on the PH value of oil. The oil detection device detects the degree of deterioration of the oil by changing the PH value of the oil and the potential difference between the two electrodes as the oil deteriorates.
As a conventional oil detection device, there is known a device in which thin electrodes are stacked to form electrodes, and a potential difference generated between the electrodes in the oil is output by alternately crossing the thin plates of the electrodes.
[0003]
[Conspiracy to be solved by the invention]
However, since the thin plate of each electrode must be electrically connected by the conductive spacer, there is a problem that the number of parts increases and the number of assembling steps increases.
In general, if current leaks between electrodes, the potential measurement accuracy between the electrodes decreases, so it is desirable to reliably insulate the electrodes. In addition, if the interelectrode resistance of the oil detection device is large, the potential measurement accuracy is lowered. The interelectrode resistance decreases as the facing area where the electrodes face each other is larger. In order to increase the facing area between the electrodes in a conventional oil detection device that constitutes each electrode by laminating thin plates, it is conceivable to increase the area of each thin plate or increase the number of thin plates. However, when the area of the thin plate is increased, there is a problem that the diameter of the oil detection device increases. Further, when the number of thin plates is increased, there is a problem that the number of parts increases and the number of assembling steps increases.
[0004]
An object of the present invention is to provide an oil detection device that can easily reduce the number of parts and can be downsized, and that can detect the degree of deterioration of oil.
[0005]
[Means for Solving the Problems]
According to the oil detection device of the first aspect of the present invention, the first electrode and the second electrode have the first fin and the second fin, respectively, extending in the axial direction and installed substantially evenly in the circumferential direction. The first fin is bent toward the second electrode, and the second fin is bent toward the first electrode so that the original position becomes a communication hole that connects the inside of the cylinder and the outside of the cylinder. Since each fin is bent at an angle of less than 90 ° from the original position, the bending tip of each fin is prevented from coming too close to the counterpart electrode excluding the fin. It is easy to make the distance between the facing surfaces of the fins facing each other and the distance between the bending tip of each fin and the cylindrical wall excluding the fin of the counterpart electrode facing each fin substantially equal. Thereby, the distribution of the current density generated between the electrodes becomes uniform, and the resistance between the electrodes can be reduced. As the interelectrode resistance decreases, the measurement accuracy, which is the ratio of the voltage generated between the electrodes to the measurement voltage actually measured from the electrodes, is improved. Therefore, the degree of oil deterioration can be detected with high accuracy.
[0006]
Furthermore, since the bending angle of the fin is less than 90 ° from the original position and the bending amount is small, cracks are unlikely to occur at the corner of the bent fin.
The original part where the fins are bent is a communication hole that communicates the inside and outside of the cylinder of each electrode, so that the oil communicates between the inside and outside of the cylinder through the communication hole, and the oil stagnates around the electrode. Therefore, the degree of oil deterioration can be detected with high accuracy.
[0007]
According to the oil detection device of the second aspect of the present invention, the fin-corresponding portion of the plate-shaped base material can be bent and formed into a cylindrical shape by cutting and bending, so that the base material is formed in order to form the electrode. It is not necessary to discard the part, and the reduction of the area where the electrodes face each other can be prevented.
[0015]
According to the oil detection device described in the above claims, since each electrode is formed in a cylindrical shape, each electrode can be constituted by a single component. Therefore, the number of parts is reduced, and the assembly man-hour is reduced. Furthermore, if the axial length of the cylindrical electrode is increased, the facing area between the electrodes can be easily increased without increasing the number of parts, and the resistance between the electrodes of the oil detection device can be reduced. Measurement accuracy of the degree of oil degradation can be increased without increasing the size.
[0016]
Further, since the electrode is formed in a cylindrical shape, a space for installing a remaining amount sensor for detecting the remaining amount of oil can be secured inside the innermost electrode. Since the degree of oil deterioration and the remaining amount of oil can be detected by a single oil detection device, the number of mounting steps is reduced compared to when the deterioration sensor and the remaining amount sensor are separately mounted on an oil pan or the like. Further, since the remaining amount sensor can be disposed in the empty space formed inside the cylindrical electrode, the outer diameter of the oil detection device does not increase even if the remaining amount sensor is provided. Therefore, it is possible to reduce the insertion hole when the oil detection device including the deterioration sensor and the remaining amount sensor is inserted into the oil pan from the outside.
[0017]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, a plurality of examples showing embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
FIG. 3 shows an oil detection apparatus according to the first embodiment of the present invention. The oil detection device 10 is attached to an oil pan of a vehicle, for example, and detects the degree of deterioration of oil used for hydraulic control and lubrication.
[0018]
A terminal 12 electrically connected to each electrode is embedded in the support member 11 formed of an insulating resin material. The cover 15 is coupled to the support member and covers the electrode structure 20. A communication hole 15 a is formed in the cover 15 so that oil flows inside and outside the cover 15. The electrode structure 20 is attached to the support member 11 with an adhesive or the like. The electrode structure 20 is immersed in oil such as an oil pan.
[0019]
As shown in FIG. 1, the electrode structure 20 includes an inner electrode pair 30 having a first electrode 31 and a second electrode 35, and is coaxial with the inner electrode pair 30 so as to surround the inner electrode pair 30 on the outer periphery of the inner electrode pair 30. It has an outer electrode pair 40 installed on top. The inner electrode pair 30 and the outer electrode pair 40 are substantially the same in shape and configuration except for the diameters. Hereinafter, the description of the inner electrode pair 30 will be mainly used to serve as the explanation of the outer electrode pair 40.
[0020]
The inner electrode pair 30 includes a first electrode 31 and a second electrode 35 disposed coaxially with the first electrode 31 outside the first electrode 31. Both electrodes are formed in a cylindrical shape. One of the two electrodes is formed of a metal whose potential does not substantially change regardless of the PH value of the oil, and the other electrode is formed of a metal whose potential changes depending on the PH value of the oil.
[0021]
As shown in FIGS. 1 and 2, the first electrode 31 has a first fin 32 that protrudes outward from the cylinder toward the second electrode 35 and extends in the axial direction. A communication hole 33 is formed between the first fin 32 and the first fin 32 adjacent to each other in the circumferential direction so that oil can flow through the cylinder inner side and the cylinder outer side of the first electrode 31. The second electrode 35 has second fins 36 that protrude inward of the cylinder toward the first electrode 31 and extend in the axial direction. A communication hole 37 is formed between the second fin 36 and the second fin 36 adjacent to each other in the circumferential direction so as to allow the oil to flow between the inner side and the outer side of the second electrode 35. Since the oil flows through the communication hole 33 and the communication hole 37, the oil does not stagnate around the electrodes. Therefore, the deterioration state of the whole oil can be detected with high accuracy.
[0022]
The first fin 32 and the second fin 36 are formed by cutting and bending a plate-shaped base material. The base material on which each fin is formed is rounded into a cylindrical shape, and both ends are welded to form each electrode.
[0023]
The number of fins formed on the first electrode 31 and the second electrode 35 is the same, and the bending angle θ1 with respect to the original cylindrical wall position before cutting and bending is the same for both electrodes, and 0 <θ1 <π / 2.
The thickness t of the first electrode 31 and the second electrode 35 may be the same or different. In the present embodiment, description will be made assuming that the thicknesses are the same. The interval δ between the electrodes including the fins is the same, and δ ≦ 1 mm is set. When the outermost diameter of the second electrode 35 is R, the inner diameter r of the first electrode 31 is r = R−2t−2δ. The angle θ2 that one fin formed in each of the first electrode 31 and the second electrode 35 occupies in the circumferential direction is the same. When the number of fins formed on both electrodes is n, θ2 = (2π / n).
[0024]
L = (2πr / n) = 2π (R−2t−2δ) where L is the length of the cylindrical wall corresponding to θ2 before the first fin 32 is formed by bending the cylindrical wall of the first electrode 31. / N. The first fin 32 is formed by bending the cylindrical wall at a half position of L so that 0 <θ1 <π / 2.
[0025]
Since the fins of both electrodes are formed at a bending angle of less than 90 °, the fins do not get too close to the electrodes facing each other. Therefore, it is easy to keep the distance between the first electrode 31 including the fin and the second electrode 35 substantially constant in the circumferential direction. Furthermore, cracks are unlikely to occur at the bent corners.
[0026]
In contrast to the voltage generated between the first electrode 31 and the second electrode 35 due to the deterioration of oil, the measurement voltage actually measured from both electrodes decreases as the interelectrode resistance increases. In order to prevent the measurement voltage from decreasing and to detect the deterioration of the oil with high accuracy, it is desired to increase the measurement accuracy, which is the ratio of the measurement voltage to the voltage generated between the electrodes. For this purpose, it is conceivable to increase the facing area between the electrodes or reduce the interelectrode resistance by reducing the distance between the electrodes. Therefore, in the first embodiment, the distance δ between the electrodes is set to a dimension region where δ ≦ 1 mm in view of both desired output of potential difference and electrode formation. As shown in FIG. 4, the measurement accuracy is set to 90% or more by setting δ ≦ 1 mm. As the distance between the electrodes is closer, the measurement accuracy is improved.
[0027]
Moreover, since each fin is formed by cutting and bending without throwing away a part of the base material, a reduction in the facing area between the electrodes is prevented.
Further, since the communication holes 33 and 37 are formed by forming the fins, the oil flows between the inside and the outside of the first electrode 31 and the second electrode 35. Since oil is prevented from stagnating around the electrode, the degree of oil deterioration can be detected with high accuracy.
[0028]
(Second embodiment)
A second embodiment of the present invention is shown in FIG.
The electrode structure 50 includes an inner electrode pair 60 and an outer electrode pair 70 installed on the outer periphery of the inner electrode pair 60 so as to surround the inner electrode pair 60. The inner electrode pair 60 has a first electrode 61 and a second electrode 65, and the outer electrode pair 70 has a first electrode 71 and a second electrode 75. Each electrode is cylindrical. The first electrode 61, the second electrode 65, the first electrode 71, and the second electrode 75 have a diameter that increases in this order, and are arranged coaxially. Each electrode has slits 62, 66, 72, 76 as communication holes extending in the axial direction and arranged at equal angular intervals in the circumferential direction. The slits 62, 66, 72, 76 are formed at the same circumferential position. Oil flows through the slits 62, 66, 72, and 76 and inside and outside the cylinder of each electrode. Since oil is prevented from stagnating around the electrode, the degree of oil deterioration can be detected with high accuracy.
[0029]
Each electrode of the second embodiment does not have a protruding portion such as a fin protruding toward the inner side or the outer side of the tube, and has the same thickness in the circumferential direction. Therefore, if each electrode is installed on the same axis, even if the rotation position of each electrode deviates from the rotation position shown in the second embodiment as in the electrode structure 80 of the modification shown in FIG. Although the area slightly decreases, the distance between the electrodes is constant in the circumferential direction. Therefore, the assembly of the electrodes is easy.
[0030]
(Third embodiment)
A third embodiment of the present invention is shown in FIG.
The electrode structure 100 includes an inner electrode pair 110 and an outer electrode pair 120 disposed on the outer periphery of the inner electrode pair 110 so as to surround the inner electrode pair 110. The inner electrode pair 110 has a first electrode 111 and a second electrode 112, and the outer electrode pair 120 has a first electrode 121 and a second electrode 122. Each electrode is cylindrical. The first electrode 111, the second electrode 112, the first electrode 121, and the second electrode 122 have a diameter that increases in this order, and are arranged coaxially.
[0031]
Since each electrode is formed in a cylindrical shape and no slit is formed as in the second embodiment, oil is prevented from flowing inside and outside the cylinder of each electrode. However, since no slit is formed, the facing area between the electrodes increases. Further, even if the rotational positions of the electrodes are deviated, the spacing between the electrodes and the opposing area between the electrodes do not change, so that positioning of the electrodes in the rotational direction is not necessary. Therefore, the assembly of the electrodes is easy.
[0032]
(Fourth embodiment)
A fourth embodiment of the present invention is shown in FIG.
The electrode structure 130 is an electrode pair having a first electrode 140 and a second electrode 150. The second electrode 150 is installed coaxially with the first electrode 140 so as to surround the first electrode 140 on the outer periphery of the first electrode 140. Both electrodes are formed by drawing.
[0033]
The first electrode 140 has protrusions 141 that protrude outside the cylinder, that is, toward the second electrode 150, extend in the axial direction, and are installed at equiangular intervals in the circumferential direction. The second electrode 150 has protrusions 151 that protrude in the cylinder, that is, toward the first electrode 140, extend in the axial direction, and are installed at equiangular intervals in the circumferential direction.
[0034]
The interval between the first protrusion 141 and the second protrusion 151 adjacent to both sides in the circumferential direction, and the inner bottom surface 152 between the second protrusion 151 adjacent in the circumferential direction at the tip of the first protrusion 141 are formed. It is equal to the interval. Further, the interval between the second protrusion 151 and the first protrusion 141 adjacent to both sides in the circumferential direction, and the inner bottom surface 142 between the first protrusion 141 where the tip of the second protrusion 151 is adjacent in the circumferential direction, The interval to be formed is equal. Therefore, the distance between the first electrode 140 and the second electrode 150 is substantially constant in the circumferential direction, including the tip of each protrusion.
[0035]
In the space 135 formed between the ends of both electrodes on the side that is not attached to the support member as described in the first embodiment, in FIG. The projection 161 of the contact preventing member 160 is fitted as shown in FIG. The contact preventing member 160 is made of an insulating material such as PPS (polyphenylene sulfide). The protrusion 161 of the contact prevention member 160 is formed in accordance with the shape of the space 135. The contact prevention member 160 prevents the electrodes from being deformed by vibrations transmitted from the vehicle or the like to the electrodes, and prevents the electrodes from being electrically connected due to the deformation. Therefore, the malfunction of the oil detection device can be prevented.
[0036]
Instead of fitting the contact preventing member 160 into the space 135, the ends of both electrodes may be immersed in a molten insulating resin material, and contact between both electrodes may be prevented by the insulating resin material solidified after cooling.
The contact preventing member 160 for preventing the end of the electrode not attached to the support member from contacting due to deformation has been described only in the fourth embodiment, but in the first embodiment, the second embodiment, and the third embodiment. However, if possible, it is desirable to use a contact prevention member to prevent contact between the electrodes.
[0037]
In the above-described embodiments of the present invention described above, since the distance between the electrodes is substantially constant in the circumferential direction, the current density distribution between the electrodes becomes uniform, and the resistance between the electrodes can be reduced. Since the measurement accuracy improves as the interelectrode resistance decreases, the degree of oil degradation can be detected with high accuracy.
[0038]
Further, since each electrode is formed in a cylindrical shape, the electrode can be formed with one component. Since the number of parts is reduced, assembly is facilitated and the oil detection device can be miniaturized. Moreover, the opposing area between electrodes can be easily increased by extending the axial length of each electrode. Furthermore, since each electrode is cylindrical, a space for installing a remaining amount sensor for detecting the remaining amount of oil can be secured inside the innermost electrode. Therefore, detection of the degree of oil deterioration and detection of the remaining amount of oil can be detected by one oil detection device.
[0039]
In the above embodiments, each electrode is formed in a cylindrical shape. On the other hand, the cylindrical shape of each electrode is not limited to a cylindrical shape as long as the cross-sectional shapes excluding the protrusions and fins are substantially the same on the surface orthogonal to the axis.
[Brief description of the drawings]
FIG. 1A is a front view showing an electrode structure of an oil detection device according to a first embodiment of the present invention, and FIG. 1B is a sectional view taken along line BB in FIG.
FIG. 2 is an enlarged view showing an electrode pair according to the first embodiment.
FIG. 3 is a cross-sectional view showing the oil detection device according to the first embodiment.
FIG. 4 is a characteristic diagram showing a relationship between an inter-electrode interval and measurement accuracy.
5A is a front view showing an electrode structure of an oil detection device according to a second embodiment of the present invention, and FIG. 5B is a sectional view taken along line BB in FIG. 5A.
6A is a front view showing an electrode structure of an oil detection device according to a modification of the second embodiment, and FIG. 6B is a sectional view taken along line BB in FIG.
7A is a front view showing an electrode structure of an oil detection device according to a third embodiment of the present invention, and FIG. 7B is a view in the direction of arrow B in FIG.
8A is a front view showing an electrode structure of an oil detection device according to a fourth embodiment of the present invention, and FIG. 8B is a view in the direction of arrow B in FIG. 8A.
9A is a perspective view showing a contact preventing member according to a fourth embodiment of the present invention, and FIG. 9B is a view in the B direction of FIG.
[Explanation of symbols]
10 Oil detection device 31, 41, 61, 71, 111, 121, 140 First electrode 35, 45, 65, 75, 112, 122, 150 Second electrode 32, 42 First fin 36, 46 Second fin 62, 72 1st slit 66, 76 2nd slit 141 1st protrusion 151 2nd protrusion 160 Contact prevention member

Claims (2)

An oil detection device that detects the degree of oil degradation based on a potential difference between electrodes,
A cylindrical first electrode, and a cylindrical second electrode disposed on the outer peripheral side of the first electrode substantially coaxially with the first electrode;
The first electrode and the second electrode each have a first fin and a second fin that extend in the axial direction and are arranged in the circumferential direction, and the first fin faces the second electrode, and the second fin Is bent at an angle of less than 90 ° from the original position so that the original position becomes a communication hole that communicates the inside and the outside of the cylinder toward the first electrode. And an interval between the bending tip of each fin and the cylinder wall excluding the fin of the mating electrode facing each fin are substantially equal.   The oil detection device according to claim 1, wherein the first fin and the second fin are formed by cutting and bending.

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