JP2001264148A - Level and viscosity measuring apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a level and viscosity measuring apparatus by which the level and the viscosity of a liquid can be measured ideally. SOLUTION: The level and viscosity measuring apparatus 1 is provided with a container 3 into which an oil is put. The measuring apparatus is provided with an ultrasonic sensor 7 which is attached to the bottom part 5 of the container 3. The ultrasonic sensor 7 is formed in such a way that a piezoelectric element 11 is bonded to a bottomed cylindrical member 9. The sensor transmits ultrasonic waves to the oil, and it can receive reflected waves of the ultrasonic waves reflected by the level. The bottomed cylindrical member 9 is provided with a cylindrical side part 13 and a diaphragm 15 which covers the oil side of the side part 13. The side part 13 and the diaphragm 15 are bonded and integrated. The piezoelectric element 11 is bonded to the inner side of the diaphragm 15. A temperature sensor 21 is arranged inside the container 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a level and viscosity measuring device capable of measuring the level and viscosity of a liquid such as oil.

[0002]

2. Description of the Related Art Conventionally, as an apparatus for detecting the level and deterioration of a liquid such as oil, for example, an integrated ultrasonic transmission / reception-based ultrasonic deterioration / level sensor (see Japanese Utility Model Application Laid-Open No. 63-122239) has been proposed.

In this technique, an ultrasonic wave is transmitted to a reflector disposed in oil, and the reflected wave is received to detect deterioration of the oil according to the degree of attenuation of the ultrasonic wave. In addition, using a float that moves in accordance with the height (level) of the liquid surface, a structure in which the reflection plate moves from the position where the ultrasonic wave is reflected when the level is lowered, and the state of reflection of the ultrasonic wave greatly changes. For example, it is determined that the level has changed.

[0004]

However, in the above-described technique, a special reflector must be used, and the reflector must be moved using a float, which complicates the structure and the movable part that moves greatly. Therefore, there is a problem that a failure easily occurs. Particularly, it is not preferable to use it by attaching it to an object having a lot of vibration such as an automobile, and further improvement has been demanded.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a level and viscosity measuring device capable of suitably measuring the level and viscosity of a liquid.

[0006]

Means for Solving the Problems and Effects of the Invention (1) According to the first aspect of the present invention, there is provided a vibrator in which at least one of the vibrating plates is formed by joining a vibrating plate and a piezoelectric element. A level and viscosity measuring device for measuring the level and viscosity of a liquid by bringing a surface into contact with a liquid and transmitting an ultrasonic wave and receiving a reflected wave of the ultrasonic wave. A level detecting unit that detects a level of the liquid based on a time from transmitting the ultrasonic wave to receiving a reflected wave thereof, wherein a transmission / reception direction of the sound wave is substantially perpendicular to a surface of the liquid, A viscometer for measuring the resonance characteristics of the diaphragm when a voltage is applied to the piezoelectric element, and measuring the viscosity of the liquid based on a change in the resonance characteristics. Requires a measuring device To.

The present invention is a measuring device capable of detecting, for example, the level (level) of a liquid level of lubricating oil (oil) of an automobile engine and its viscosity (and thus deterioration).
First, in the level detecting means of the present invention, the transmitting and receiving direction of the ultrasonic wave of the vibrator is made substantially perpendicular to the surface of the liquid (hereinafter, also simply referred to as the liquid surface), and the ultrasonic wave is transmitted to the liquid surface. The time until the reflected wave is received (transmission / reception time) is measured.

Since the transmission / reception time varies depending on the height of the liquid surface, measuring the transmission / reception time makes it possible to detect the distance from the vibrator (the surface of the vibrator) to the liquid surface.
Further, in the viscosity measuring means of the present invention, when an alternating current (alternating voltage) is applied to the piezoelectric element, resonance characteristics (for example, resonance point and resonance amplitude) of the diaphragm that can resonate (vibrate) by the electrostrictive action of the piezoelectric element itself are provided. ) Is measured.

That is, for example, a vibrating plate having a piezoelectric element adhered to one surface and having a fixed outer periphery resonates when an alternating voltage is applied to the piezoelectric element. Here, the diaphragm is
Since the surface opposite to the surface on which the piezoelectric element is attached is in contact with the liquid, the resonance characteristics of the diaphragm differ depending on the nature and type of the surrounding liquid. Take a value (frequency). Therefore, the viscosity of the liquid can be measured by detecting the resonance characteristics.

[0010] Particularly in a liquid such as oil, for example,
Since the increase in viscosity directly indicates deterioration, measuring the viscosity of oil or the like will detect deterioration. Further, in the present invention, an ultrasonic sensor is configured using a vibrator formed of a diaphragm and a piezoelectric element, and both the level and the viscosity of the liquid can be measured by the sensor, so that the configuration is simple. In addition, since there is no large movable part like the conventional float, there is an effect that it is difficult to break down. Therefore,
This is preferable for measuring the state of oil in a vehicle having a lot of vibration such as an automobile.

Further, according to the present invention, when detecting a change in the level of the liquid surface, the ultrasonic wave is transmitted substantially perpendicularly to the liquid surface to be measured, and is reflected by the liquid surface to receive the reflected wave. I have to. This has the advantage that the change in the liquid level can be detected precisely and constantly, unlike the case where the change in the liquid level is detected based on whether or not a certain reference (constant value) is satisfied.

(2) A second aspect of the present invention is to provide a cylindrical member which is provided substantially vertically from one surface of the vibrator, which comes into contact with the liquid, toward the surface of the liquid, over the surface of the liquid. Wherein the cylindrical body is arranged so as to surround the liquid positioned in the direction of transmission and reception of the ultrasonic waves, and the liquid inside the cylindrical body and the liquid outside are communicated with each other. The gist is the level and viscosity measuring device according to claim 1.

In the present invention, the liquid positioned in the transmitting / receiving direction of the ultrasonic wave is surrounded by the cylindrical body. Therefore, even if the liquid level fluctuates (waps) under the influence of vibrations or the like from the outside, the fluctuation of the liquid level can be suppressed by the cylindrical body, and therefore, the liquid level is always substantially perpendicular to the liquid level. Ultrasonic waves can be transmitted and reflected. This has the effect that the liquid level can be accurately measured.

(3) According to a third aspect of the present invention, at least one surface of the vibrating plate of the vibrator formed by joining the vibrating plate and the piezoelectric element is brought into contact with a liquid to transmit ultrasonic waves and to transmit the ultrasonic waves. A level and viscosity measuring device for measuring the level and viscosity of a liquid by receiving a reflected wave of a sound wave, wherein a transmitting and receiving direction of ultrasonic waves of the vibrator is substantially parallel to a surface of the liquid, Level detection means for detecting the level of the liquid based on the time from transmitting the ultrasonic wave to receiving the reflected wave, and measuring the resonance characteristics of the diaphragm when a voltage is applied to the piezoelectric element And a viscosity measuring device for measuring the viscosity of the liquid based on a change in the resonance characteristic.

In the present invention, the principle of measuring the level and viscosity of the liquid surface is the same as that of the first aspect of the present invention, so that the same effect is obtained. In particular, in the present invention, for example, an ultrasonic wave is transmitted in parallel to the liquid surface, and it receives a reflected wave reflected by a wall surface or the like on the opposite side, so that when the liquid surface level changes above and below the vibrator, Causes a clear change in the time until the reflected wave is received. Therefore, a change in the liquid level can be reliably detected.

Further, since the ultrasonic wave is transmitted and reflected substantially parallel to the liquid surface, the change in the liquid surface level can be detected without being affected by the fluctuation (wave) of the liquid surface. (4) The invention according to claim 4 is characterized by comprising a temperature sensor for measuring the temperature of the liquid, and correcting the level and viscosity of the liquid according to the temperature of the liquid measured by the temperature sensor. The gist is the level and viscosity measuring device according to any one of claims 1 to 3 described above.

In the present invention, the temperature of the liquid is measured by the temperature sensor, and the level and viscosity of the liquid are corrected based on the temperature data. Can be measured. (5) The invention according to claim 5 is characterized in that the container accommodating the liquid includes:
A bottomed tubular member comprising the diaphragm and a cylindrical side portion is arranged, and one surface of the diaphragm is brought into contact with a liquid, and the piezoelectric element is joined to the other surface. The gist is the level and viscosity measuring device according to any one of the first to fourth aspects.

The present invention exemplifies the configuration of an ultrasonic sensor for transmitting and receiving ultrasonic waves. Therefore, by transmitting and receiving ultrasonic waves using this vibrator, the level and viscosity of the liquid can be measured. (6) According to a sixth aspect of the present invention, in the level and viscosity measurement according to the fifth aspect, wherein the bottomed cylindrical member is formed by integrally forming a diaphragm and a side portion. The device is the gist.

The present invention exemplifies a bottomed cylindrical member constituting the outer portion of the ultrasonic sensor. Here, the bottomed tubular member has an advantage that its manufacture can be simplified since the diaphragm and the side portions are formed by integral molding. (7) The invention according to claim 7 is characterized in that the bottomed tubular member has a diaphragm and a side part formed separately, and these are joined and integrated. The gist is the level and viscosity measurement device described in Item 5.

The present invention exemplifies a bottomed cylindrical member constituting the outer portion of the ultrasonic sensor. Here, since the bottomed tubular member is integrally formed by joining the side plate and the separate diaphragm, there is an advantage that a material suitable for the purpose can be used. For example, a material having good vibration characteristics can be selected and used as the diaphragm.

(8) The invention of claim 8 is characterized in that a rod-shaped portion is erected substantially perpendicularly to one surface of the vibration plate which comes into contact with liquid. The gist is a level and viscosity measuring device described in any of them.

With this rod-shaped portion, when the diaphragm is vibrated, its resonance characteristics are greatly affected by the viscosity of the liquid, and the viscosity of the liquid can be detected more accurately. (9) The invention according to claim 9 is characterized in that a guide extending along the axial direction of the rod portion is arranged close to the outer peripheral side of the rod portion. The gist is a viscosity measurement device.

When such a guide is provided along the rod-shaped portion and in a form having a gap between the guide and the rod-shaped portion, the movement of the rod-shaped portion other than the axial direction is suppressed, so that the sensitivity is improved. There are advantages. The gap between the rod portion and the guide is preferably 0.5 mm or less.

Here, in each of the above-mentioned inventions, substantially vertical (or substantially horizontal) means a range of a predetermined angle θ (tilt angle) centered on the vertical (or horizontal) so that the effects of the invention can be obtained. Although it is technically almost vertical (or almost horizontal), truly vertical (or horizontal) is desirable.

As shown in FIG. 1, the ultrasonic wave has an incident angle θ _in = reflection angle θ _out with respect to a reflection surface (liquid surface).
Therefore, for example, an ultrasonic wave emitted from one end of a circular element (a vibrator having a piezoelectric element; a sensor) has a depth D (distance to a reflecting surface in the case of horizontal), a radius R of the element, Assuming that the inclination angle is θ, when the condition of θ> tan ⁻¹ (R / D) is satisfied, the reflected wave deviates from the element and reception becomes impossible. Therefore, considering the range of the inclination angle θ (= θ _K ), it is important that the above condition is satisfied.

However, with regard to the rod-shaped portion of the eighth aspect,
Since the principle is different from the above condition, a sufficient effect can be obtained within a range of, for example, 5 ° with respect to one plane of the diaphragm.

[0027]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment (embodiment) of a level and viscosity measuring apparatus according to the present invention will be described below with reference to the drawings. (Example 1) Considering the lubricating oil (oil) of an automobile engine, for example, it is considered that a change in the viscosity of the oil indicates the deterioration of the oil. An example will be given in which the oil level (liquid level; depth) is measured together with the measurement.

A) First, the device configuration of the level and viscosity measuring device of the present embodiment will be described. As shown in FIG. 2, a level and viscosity measuring device (hereinafter simply referred to as a measuring device) 1
Has a container 3 containing oil and an ultrasonic sensor 7 attached to the bottom 5 of the container 3.

This ultrasonic sensor 7 has a piezoelectric element 11 joined to the inside of a bottomed cylindrical member 9 which is cylindrical and closed on the oil side, and transmits ultrasonic waves to oil. The sensor is capable of receiving a reflected wave of the ultrasonic wave reflected on the liquid surface. The bottomed tubular member 9 has a cylindrical portion (side portion) 13 made of stainless steel fixed to the container 3 and a disk-shaped lid made of an iron-nickel alloy that covers the oil side of the bottomed tubular member 9. And the periphery of the diaphragm 15 is integrally joined to the side portion 13 by brazing or the like. The diaphragm 15 has a diameter of about 18 m, for example.
It is a disk having a thickness of 0.2 mm and a thickness of 0.2 mm.

The piezoelectric element 11 is provided inside the diaphragm 15.
Are bonded by an adhesive or the like. A first lead 17 is connected to the piezoelectric element 11, and a second lead 19 is connected to the side portion 13. When transmitting an ultrasonic wave, for example, a sine wave or the like is connected to the two leads 17, 19. An alternating current (alternating voltage) is applied. The vibration plate 15 and the piezoelectric element 11 joined to each other are referred to as a vibrator 20, and ultrasonic waves are transmitted when the piezoelectric element 11 vibrates.

In addition to the above-described configuration, a temperature sensor 21 is disposed in the container 3, and the temperature sensor 21 measures the temperature of the oil. The ultrasonic sensor 7 and the temperature sensor 21 are connected to an electronic control unit (ECU) 23 mainly including a microcomputer.

The ECU 23 transmits an ultrasonic wave to the liquid surface by applying an alternating voltage to the piezoelectric element 11 and vibrates the piezoelectric element 11 as described later, and receives the reflected wave. The level and viscosity of the oil can be measured based on the information of the transmission and reception and the resonance characteristics of the diaphragm 15.

In measuring the level and viscosity, the temperature of the oil is measured based on the signal from the temperature sensor 21 and the data for measuring the level and viscosity of the oil based on the temperature information. Can be corrected. In the case of the present embodiment, the allowable range of the displacement (tilt angle θ) of the axis center of the vibrator is within 5 ° from the axis center perpendicular to the horizontal liquid surface.

B) Next, a method of measuring the oil level by the measuring device 1 will be described. As shown in FIG.
3 shows an electrical configuration for measuring a level. In the measuring device 1 of the present embodiment, a voltage is applied to the piezoelectric element 11 from the voltage applying unit (power supply) 25. That is, both leads 1
An alternating voltage having a fixed frequency is applied to the piezoelectric element 11 via the elements 7 and 19, thereby transmitting ultrasonic waves (transmission waves) from the piezoelectric element 11 via the diaphragm 15.

Since the transmitted ultrasonic wave is reflected on the liquid surface, the reflected wave is received by the vibrator 20. That is, since the diaphragm 15 vibrates due to the reflected wave and the piezoelectric element 11 receives the pressure of the vibration, the voltage generated by the vibration is measured. This change in voltage is shown in FIG.
It can be seen that a large voltage is generated during transmission and reception.

Accordingly, this voltage is determined by a certain determination value to obtain a signal indicating the time of transmission and a signal indicating the time of reception as shown in FIG. Specifically, in the comparison circuit, the threshold value is sufficiently smaller than the voltage of the reflected wave, and
A determination pulse is output when the voltage received by the piezoelectric element 11 from the reflected wave exceeds a threshold value in a state where the level is set sufficiently higher than the background noise. And
A time (transmission / reception time) T between the two signals is measured. The transmission / reception time T is a time from transmission of ultrasonic waves to reception of the ultrasonic waves.

Therefore, the level (distance from the surface of the diaphragm 15 to the liquid surface; depth) D can be calculated by the following equation (1). D = (1/2) T · Sp (1) where Sp is the speed of sound in oil.

Since this sound speed is a value determined by the oil temperature, it is corrected by the oil temperature measured by the temperature sensor 21. That is, the higher the oil temperature, the lower the sound speed. Therefore, a map indicating the relationship between the oil temperature and the sound speed is stored in the ECU 23 in advance, and the map is used to calculate the level. The sound speed is corrected according to the temperature of the sound. For example, if the temperature is low,
By correcting the sound speed to be lower, the level D is corrected to be lower.

C) Next, a method for measuring the viscosity of oil by the measuring device 1 will be described. FIG. 4A shows an electrical configuration for measuring the viscosity (viscous resistance) of oil. In the measuring device 1 of the present embodiment, an alternating voltage having a changed frequency is applied to the piezoelectric element 11 from the voltage applying unit 25. For example, the frequency is swept from the frequency f _L to the frequency f _H, and the voltage across the piezoelectric element 11 at this time is measured to determine the impedance.

The piezoelectric element 1 when this frequency is changed
FIG. 4 (b) shows a change in the voltage at both ends of No. 1;
(Resonance frequency). Further, as shown in FIG. 5 described later, the inflection point of the minimum value at which the impedance decreases and turns to increase is the resonance point (resonance frequency) of the diaphragm 15. Further, the width from the inflection point of the minimum value to the inflection point of the maximum value at which the impedance changes from increasing to decreasing is the amplitude (resonance amplitude). Note that characteristics such as the resonance frequency and the resonance amplitude that occur with resonance are referred to as resonance characteristics.

Since the resonance frequency and the resonance amplitude change when the viscosity changes, the resonance frequency and the resonance amplitude decrease when the viscosity increases (the oil deteriorates). By changing the amplitude,
A change in oil viscosity can be detected.

For example, as shown in FIG. 4B, in the case of a new oil, the viscosity is low, so that the resonance frequency f ₀ is high,
For deteriorated oil, the resonance frequency f ₁ is a phenomenon that decreases, it is possible to measure the degree of oil degradation from the resonance frequency. Therefore, when measuring the degree of oil deterioration, the distance between both leads of the piezoelectric element 11 must be one.
The voltages at 7 and 19 are monitored, the inflection point of the minimum value of the impedance is detected, and the frequency at the inflection point is determined as the resonance frequency. Alternatively, the amplitude between the inflection points of the minimum value and the maximum value is obtained. Note that both the resonance frequency and the amplitude may be obtained.

Then, the deterioration of the oil is determined from the map indicating the relationship between the resonance frequency and the viscosity of the oil stored in the ECU 23 and the map indicating the relationship between the resonance amplitude and the viscosity of the oil. Since the viscosity of the oil changes depending on the temperature, in this case as well, the correction based on the temperature is performed as in the measurement of the level. That is, as the temperature decreases, the viscosity of the oil increases. Therefore, a map indicating the relationship between the temperature and the viscosity of the oil is stored in the ECU 23 in advance, and the viscosity of the oil is corrected using this map. For example, when the temperature is low, the measured viscosity of the oil is corrected to be lower.

Experimental Example 1 Next, Experimental Example 1 in which the relationship between the actual resonance frequency and resonance amplitude of the diaphragm 15 and the viscosity of oil is measured will be described. Ultrasonic waves were transmitted to the new oil and the degraded oil using the measuring device 1 under the following conditions, and the voltage (impedance / Ω) and frequency (KHz) at both ends of the piezoelectric element 11 at that time were measured. The same measurement was performed on water as a reference example. The result is shown in FIG.

<Measurement conditions>Oil; SJ class 5W-30 Temperature; Room temperature (approximately 25 ° C) <Oil used>-New oil-Degraded oil (equivalent to 40,000 km running) Engine bench durable Engine: 1UZ-FE, V8, 4L (endurance conditions) Idling; exhaust temperature 350 ° C × 10 minutes 3400 rpm; exhaust temperature 925 ° C. × 30 minutes 2800 rpm; exhaust temperature 890 ° C. × 20 minutes 449 cycles of the above cycle Viscosity of new oil (low viscosity oil) Viscosity) is 76 mPa
・ S and small. Therefore, as shown in FIG. 5, it can be seen that the resonance frequency is as large as 10.30 KHz and the resonance amplitude (of impedance) is as large as 0.31 KΩ.

On the other hand, the viscosity of the deteriorated oil (high-viscosity oil) is as large as 190 mPa · S. Therefore, the resonance frequency is 10.23 KHz and the resonance amplitude is 0.29 KΩ.
It turns out that it is small like In addition, the viscosity of water is 1 mPa
Since s is much smaller than other oils, the resonance frequency is 10.36 KHz and the resonance amplitude is 0.38 KΩ, which is larger than other oils.

As is clear from this experimental example, the resonance frequency and the resonance amplitude are different between the new oil and the deteriorated oil. Therefore, the viscosity of the oil, and hence the degree of deterioration of the oil, can be accurately determined from the resonance frequency and the resonance amplitude of the oil. It can be seen that it can be detected. Experimental Example 2 Next, an experimental example in which the relationship between the tilt angle θ of the ultrasonic sensor and the reception level was measured will be described.

Using the measuring device 1 described above, the depth of a new oil (same temperature) similar to that of the first experimental example was changed, and ultrasonic waves were transmitted to the oil. At this time, as shown in FIG. 6, the inclination angle θ of the ultrasonic sensor (specifically, the vibrator)
Was changed, and the reception level at that time was measured. FIG. 6 shows the result.

As is apparent from FIG. 6, when the reception level changes depending on the inclination angle, and the voltage applied to the piezoelectric element from the reflected wave is set so that the judgment pulse is output with a threshold of 50 mV, the depth and the measurement The relationship between the limits (inclination angles) is as shown in Table 1 below.

[0050]

[Table 1]

As is apparent from Table 1 and FIG. 6,
It can be seen that the reception level decreases as the depth increases and the tilt angle θ increases. Therefore, for example, when the depth to be measured is 50 mm or less, setting the inclination angle θ to be within 6.5 ° is sufficient for practical use because the reception level is 5 mV or more. That is, the tilt angle θ may be determined according to the depth to be measured so that a reception level sufficient for the measurement is obtained.

D) This embodiment has the following effects by the above-described configuration. The measuring device 1 of the present embodiment can accurately detect the oil level based on the transmitted wave transmitted by the ultrasonic sensor 7 and the received wave. In addition, the degree of oil deterioration can be accurately detected based on the resonance frequency and / or resonance amplitude of the diaphragm 15 using the same ultrasonic sensor 7.

Further, since the correction based on the temperature is performed, the level and the deterioration of the oil can be measured more accurately. (Embodiment 2) Next, Embodiment 2 will be described.

The description of the same parts as in the first embodiment will be omitted or simplified. As shown in FIG. 7, the level and viscosity measuring device 31 of the present embodiment includes a container 3 containing oil.
An ultrasonic sensor 37 is attached to the side wall 35 of the third. That is, the bottomed cylindrical member 39 of the ultrasonic sensor 37 is
The center of the axis is arranged in the horizontal direction in the figure, and the vibrator 44 composed of the vibration plate 41 and the piezoelectric element 43 is arranged in the vertical direction in the figure. The temperature sensor is not shown.

Therefore, the ultrasonic wave transmitted from the vibrator 44 is transmitted toward the left side of the figure (accordingly, substantially parallel to the liquid surface), and is reflected by the opposite side wall 35. To the right, and is received by the transducer 44. In the case of the present embodiment, the allowable range of the deviation (tilt angle θ) of the axis center of the vibrator 44 is within 5 ° from the axis center perpendicular to the side wall 35.

In this embodiment, the oil level is
The transmission / reception time T from transmission to reception of an ultrasonic wave differs depending on whether the transmission level is above or below 4 (in other words, whether or not the oil level satisfies a certain value). Oil level can be detected.

Further, the deterioration of the oil can be detected in the same manner as in the first embodiment, and the same effect can be obtained. Third Embodiment Next, a third embodiment will be described.

The description of the same parts as in the first embodiment is omitted or simplified. As shown in FIG. 8, the level and viscosity measuring device 51 of the present embodiment has the same basic configuration as that of the first embodiment, but differs in that a cylindrical body 53 is used. The cylindrical body 53 has a cylindrical shape with an open upper end, and is externally fitted to an upper end of a side portion 57 of the ultrasonic sensor 55.
It is arranged coaxially with the ultrasonic sensor 55.

That is, the cylindrical body 53 is set up substantially perpendicularly to the oil level and the vibration plate 65, and
9 is arranged so as to surround the periphery of the space above, and its upper end protrudes above the oil level. The cylindrical body 53 has a communication hole 61 for communicating oil inside and outside the cylindrical body 53.
Is provided, and the cylindrical body 53 is formed by the communication hole 61.
Inside and outside are the same. Further, a temperature sensor 63 is disposed inside the cylindrical body 53.

In this embodiment, the same effects as those of the first embodiment can be obtained, and the liquid surface on which the ultrasonic wave is reflected can be used as the cylindrical body 53.
, There is an advantage that even when the container is vibrated, there is little change in the liquid level and the level can be detected more accurately.

When the cylindrical body 53 is cut along a plane including its own axis, the cross section of the side peripheral portion 53a may be formed linearly as shown in FIG. ,
It may be formed in an inward curved shape. (Embodiment 4) Next, Embodiment 4 will be described.

The description of the same parts as in the first embodiment will be omitted or simplified. As shown in FIG. 9A, in the present embodiment, the configuration of the ultrasonic sensor 71 is different from that of the first embodiment. In other words, the bottomed cylindrical member 73 constituting the outer portion of the ultrasonic sensor 71 is a disk-shaped diaphragm 75 and a cylindrical side portion 77 in which the same metal block is rolled and integrally formed. is there.

The piezoelectric element 79 is provided inside the diaphragm 75.
And a vibrator 83 is formed in a form in which the piezoelectric element 79 is molded with the resin 81, and a pair of leads 85 and 87 extend from the piezoelectric element 79 through the resin 81. According to this embodiment, the first embodiment is also used.
The same effect as described above is obtained, and in particular, the bottomed cylindrical member 73
Is easy to form. (Fifth Embodiment) Next, a fifth embodiment will be described.

The description of the same parts as in the first embodiment is omitted or simplified. As shown in FIG. 9B, in the present embodiment, the configuration of the ultrasonic sensor 91 is different from that of the first embodiment. That is, the piezoelectric element 95 is provided inside the diaphragm 93.
The diaphragm 93 on the side that comes into contact with oil
A rod-shaped portion (piston) 97 is joined substantially vertically to the surface.

The rod 97 has a length of, for example, about 20 mm.
Is a square prism having a square cross section (for example, 5 mm on a side). In the case where the diaphragm 93 only vibrates, the influence of the weight of the oil increases, but the provision of the rod-shaped portion 97 makes it possible to more accurately detect the viscosity of the oil.

The shape of the rod portion 97 is not particularly limited, but is preferably a shape that is greatly affected by viscosity, such as an elongated column. (Embodiment 6) Next, Embodiment 6 will be described.

The description of the same parts as in the first embodiment is omitted or simplified. a) In the present embodiment, a guide is added to the configuration of the fifth embodiment. As shown in the cross-sectional view of FIG. 10, in the present embodiment, the inside of the diaphragm 103 of the ultrasonic sensor 101 is
A piezoelectric element 105 is joined, and a rod-like portion 107 is joined substantially vertically to the surface of the vibration plate 1033 on the side that comes into contact with the oil.

The rod-like portion 107 has a length of about 20 m, for example.
m and a column having a circular cross section (for example, a diameter of 8 mm). Further, in this embodiment, a guide 109 is provided on the outer peripheral side of the rod-shaped portion 107 so as to extend along the rod-shaped portion 107 in the axial direction.

The guide 109 is a cylindrical member erected on the outer peripheral end of the diaphragm 103. The guide 109 protrudes from the middle of the guide 109 toward the rod 107, so that the distal end of the rod 107 can be formed. It covers around. That is, the guide 109 is about 0.5 m
It is close to the rod 107 so that a ring-shaped gap 111 of m is formed.

According to this configuration, the shaft 107 of the rod-shaped portion 107 is prevented from being displaced in comparison with the example without the guide 109, so that the sensitivity is further improved. b) Next, an experimental example performed to confirm the effect of the present embodiment will be described. First, as the ultrasonic sensors used in the experiment, the ultrasonic sensor of Example 5 having only a rod-shaped portion (piston) and the ultrasonic sensor of Example 6 with a guide were used.

Then, using these ultrasonic sensors,
Oils with different viscosities, specifically, new oils (viscosity:
Viscosity 76 mPa · S) and degraded oil (viscosity: viscosity 2)
(00 mPa · S), the change rate of the resonance frequency was measured. The result is shown in FIG.

As is clear from FIG. 11A, in the ultrasonic sensor of the present embodiment with a guide, the change rate of the change of the resonance frequency with respect to the change of the viscosity is larger than that of the non-guided ultrasonic sensor. It can be seen that the viscosity can be measured accurately. Similarly, using the ultrasonic sensor of the fifth embodiment having only the rod-shaped portion (piston) and the ultrasonic sensor of the sixth embodiment with a guide, the amplitude change rate was evaluated for new oil and deteriorated oil having different viscosities. Was measured. The result is shown in FIG.
(B).

As is clear from FIG. 11B, the ultrasonic sensor of the present embodiment with a guide has a larger change in the amplitude change rate with respect to the change in viscosity than the non-guided example, and It can be seen that the viscosity can be measured well. Incidentally, the present invention is not limited to the above-described embodiment,
Of course, it can be implemented in various ways within the scope of the present invention.

For example, when there is not much temperature change, the temperature sensor may be omitted. In addition, the liquid to be measured is not limited to the lubricating oil of an automobile engine,
Of course, it is also possible to apply to paint and the like.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a relationship between tilt angles.

FIG. 2 is an explanatory diagram illustrating the entire system of the level and viscosity measuring device according to the first embodiment.

3A and 3B show a configuration for measuring the level of the first embodiment, FIG. 3A is an explanatory diagram showing an electrical configuration, FIG. 3B is a graph showing an ultrasonic signal, and FIG. It is an explanatory view showing a time from reception to reception.

FIGS. 4A and 4B show a configuration for measuring viscosity in Example 1, wherein FIG. 4A is an explanatory diagram showing an electrical configuration, and FIG. 4B is a graph showing a resonance frequency.

FIG. 5 is a graph of an experimental example showing a resonance frequency and a resonance amplitude of the first embodiment.

FIG. 6 is an explanatory diagram illustrating a relationship between a reception level, a depth, and a tilt angle.

FIG. 7 is an explanatory diagram illustrating a level and viscosity measuring device according to a second embodiment.

FIG. 8 is an explanatory diagram illustrating a level and viscosity measuring device according to a third embodiment.

9A and 9B are diagrams illustrating another embodiment, in which FIG. 9A is an explanatory diagram illustrating an ultrasonic sensor according to a fourth embodiment, and FIG. 9B is an explanatory diagram illustrating an ultrasonic sensor according to a fifth embodiment.

FIG. 10 is an explanatory diagram illustrating a level and viscosity measuring device according to a sixth embodiment.

11A and 11B show experimental results of Example 6, in which FIG. 11A is a graph showing a relationship between viscosity and a change rate of a resonance frequency, and FIG. 11B is a graph showing a relationship between viscosity and an amplitude change rate.

[Explanation of symbols]

 1, 31, 51: Level and viscosity measuring device 7, 37, 55, 71, 91, 101 ... Ultrasonic sensor 9, 39, 57, 73 ... Bottomed cylindrical member 11, 43, 79, 95, 105 ... Piezoelectric Element 15, 41, 75, 93, 103: Vibrating plate 20, 44, 59, 83, 99: Vibrator 21, 63: Temperature sensor 23: Electronic control unit (ECU) 53: Cylindrical body 97, 107: Rod body

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2F014 AA01 AA04 AB01 AB02 AC04 FB01 2G047 AA01 BC00 BC02 BC04 BC18 CA01

Claims (9)

[Claims] 1. A vibrator formed by joining a vibration plate and a piezoelectric element, wherein at least one surface of the vibration plate is brought into contact with a liquid to transmit an ultrasonic wave and receive a reflected wave of the ultrasonic wave. According to the level and viscosity measuring device for measuring the level and viscosity of the liquid, the transmitting and receiving direction of the ultrasonic wave of the vibrator is substantially perpendicular to the surface of the liquid, and the ultrasonic wave is transmitted Level detection means for detecting the level of the liquid, based on the time until receiving the reflected wave, and measuring the resonance characteristics of the diaphragm when a voltage is applied to the piezoelectric element, to the change in the resonance characteristics And a viscosity measuring means for measuring the viscosity of the liquid based on the viscosity. 2. A vibrator is provided with a tubular body which is erected substantially vertically from one surface of the vibrator, which comes into contact with the liquid, to the surface of the liquid, over the surface of the liquid. 2. The level according to claim 1, wherein the liquid is disposed so as to surround the liquid positioned in the transmission / reception direction of the ultrasonic waves, and the liquid inside the cylindrical body and the liquid outside are communicated with each other. 3. And viscosity measuring device. 3. A vibrator formed by joining a vibration plate and a piezoelectric element, wherein at least one surface of the vibration plate is brought into contact with a liquid to transmit ultrasonic waves and receive reflected waves of the ultrasonic waves. A level and viscosity measuring device for measuring the level and viscosity of the liquid, wherein the transmitting and receiving direction of the ultrasonic waves of the vibrator is substantially parallel to the surface of the liquid, and the ultrasonic waves are transmitted. Level detection means for detecting the level of the liquid, based on the time until receiving the reflected wave, and measuring the resonance characteristics of the diaphragm when a voltage is applied to the piezoelectric element, to the change in the resonance characteristics And a viscosity measuring means for measuring the viscosity of the liquid based on the viscosity. 4. The apparatus according to claim 1, further comprising a temperature sensor for measuring a temperature of the liquid, wherein the level and the viscosity of the liquid are corrected in accordance with the temperature of the liquid measured by the temperature sensor. 4. The level and viscosity measuring device according to any one of claims 3 to 3. 5. A bottomed tubular member comprising said diaphragm and a cylindrical side portion is disposed in a container for containing said liquid, and one surface of said diaphragm is brought into contact with the liquid and said other surface is contacted with said liquid. The level and viscosity measuring device according to claim 1, wherein the piezoelectric element is bonded to a surface. 6. The level and viscosity measuring device according to claim 5, wherein the bottomed cylindrical member is formed by integrally forming a vibration plate and a side portion. 7. The cylinder according to claim 5, wherein the bottomed tubular member has a diaphragm and a side part formed separately, and these are joined and integrated. Level and viscosity measuring device. 8. The level and viscosity according to claim 1, wherein a rod-like portion is erected substantially perpendicularly to one surface of the diaphragm that comes into contact with the liquid. measuring device. 9. The level and viscosity measuring device according to claim 8, wherein a guide extending along an axial direction of the rod portion is disposed close to an outer peripheral side of the rod portion.