JP2002131298A - Liquid level deterioration detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a liquid level deterioration detection device for accurately detecting the level of a liquid surface and the degree of deterioration using a simple constitution. SOLUTION: The oil level deterioration detection device 1 has an ultrasonic sensor 7 at a bottom section 5 of a container 3 having oil. A transmission side electrode 17 is provided at the side of a diaphragm 15 of a piezoelectric element 11, and a pair of signal side electrodes 19 (an electrode 19a for detecting deterioration and an electrode 19b for detection a level) is provided on the opposite side. Especially the transmission side electrode 17, that is provide at the side of the diaphragm 15 of the piezoelectric element 11, is formed into a disc shape, but the electrode 19a for detecting deterioration and the electrode 19b for detecting a level being provided at the opposite are in a semi-circular shape, where a circle is cut at the center. Also, a reflection section 27 for reflecting ultrasonic waves is provided at the outside of the diaphragm 15, and has a reflecting plate 27a, a support section 27b, and a region separation plate 27c.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid level deterioration detecting device capable of detecting both the level of a liquid such as oil and the degree of deterioration thereof using ultrasonic waves.

[0002]

2. Description of the Related Art Conventionally, for example, lubricating oil (oil) for automobiles and the like is mixed with minute impurities and the like, and the initial performance of the oil deteriorates (that is, the oil deteriorates). As the amount of oil decreases (that is, the oil level decreases), a technique described in, for example, Japanese Utility Model Laid-Open No. 63-122239 has been proposed as a device for detecting the deterioration and level of oil.

In this technique, an ultrasonic wave is transmitted to a reflector disposed in oil, the reflected wave is received, and deterioration of the oil is detected 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 by using a float. There is a problem that it is easy to break down because there is a part. In particular, it is not preferable to use it by attaching it to violent vibrations such as automobiles,
Further improvement is required.

On the other hand, a technique of arranging a reflector in the transmission direction of the ultrasonic wave and detecting the deterioration of the oil by using the reception level of the reflected wave from the reflector (Japanese Utility Model Application Laid-Open No. 63-122).
No. 261), a hole is made in a part of the reflector, and the ultrasonic waves reach the liquid surface, so that the received waves reflected by the liquid surface and the reflector can be used to deteriorate the oil and reduce the oil deterioration. A method of detecting the level can be considered.

However, in that case, the ultrasonic wave is reflected by the liquid surface and the reflector, and both received waves are detected.
There is a problem that it is not easy to detect oil deterioration and level by analyzing the received wave. The present invention has been made to solve such a problem, and its purpose is to:
It is an object of the present invention to provide a liquid level deterioration detection device that can accurately detect a liquid level and a degree of deterioration with a simple configuration.

[0007]

Means for Solving the Problems and Effects of the Invention (1) According to the first aspect of the present invention, at least one surface of a vibrating plate formed by joining a vibrating plate and a piezoelectric element is brought into contact with a liquid. A liquid level deterioration detection device that transmits ultrasonic waves in the liquid and receives reflected waves of the ultrasonic waves to detect the level of the liquid and the degree of deterioration of the liquid, wherein the piezoelectric element is A transmitting-side electrode provided on the diaphragm side, and a signal-side electrode provided on the side opposite to the transmitting-side electrode, and the signal-side electrode has a voltage when detecting the level of the liquid. And a deterioration detection electrode for applying a voltage when detecting the degree of deterioration of the liquid are provided electrically separated from each other, and further, the level detection electrode and the transmitting side are provided. Applying voltage between electrodes An ultrasonic wave generated by applying a voltage between the deterioration detection electrode and the transmission side electrode and an ultrasonic wave generated by applying a voltage between the deterioration detection electrode and the transmission side electrode are provided with a region separating unit so as not to be transmitted / received to a region other than a target region. The gist is a liquid level deterioration detection device characterized by the following.

According to the present invention, a level detecting electrode used for detecting a level and a level detecting electrode used for detecting deterioration of a liquid are used instead of providing a single signal side electrode on a piezoelectric element as in the prior art. And provided separately from the deterioration detection electrode.
On the liquid side of the diaphragm, so that the ultrasonic waves generated by the use of the deterioration detection electrode and the ultrasonic waves generated by the use of the level detection electrode are not transmitted and received except in the target area,
An area separation unit is provided.

Therefore, when detecting the level of the liquid, a voltage (for generating ultrasonic waves) is applied between the transmitting side electrode and the level detecting electrode, thereby separating the diaphragm from the diaphragm at the region separating section. The transmission and reception of the ultrasonic wave can be performed only to the selected area, and the level of the liquid can be accurately detected by using the ultrasonic wave (for example, the ultrasonic wave reflected from the surface of the liquid: the received wave).

In order to detect the degree of deterioration of the liquid, a voltage (for generating ultrasonic waves) is applied between the transmitting electrode and the deterioration detection electrode, so that the diaphragm is applied to the region separating section. The transmission and reception of ultrasonic waves can be performed only in the region separated by the above-described method, and the reflected wave (for example, the ultrasonic wave reflected by a reflector provided at a predetermined position: the received wave) can be used to accurately degrade the liquid. Can be detected.

That is, in the present invention, the detection of the liquid level and the degree of deterioration can be performed simultaneously using one vibrator. There is an effect that can be made compact. Moreover, unlike the conventional case, there is no large movable part such as a float, so that there is an effect that it is difficult to break down.
Therefore, it is preferable for detecting deterioration and level of oil in a vehicle having a lot of vibration such as an automobile.

Further, by using the apparatus of the present invention, the detection of the level of the liquid and the detection of the degree of deterioration can be carried out at different timings by using different electrodes and the like. Thus, it is possible to more reliably prevent the reception wave for detecting the level and the reception wave for detecting the degree of deterioration from being mixed. Therefore, there is an advantage that the analysis of the received wave is easier and the measurement accuracy is high.

(2) The invention according to claim 2 is characterized in that the level detection electrode and the deterioration detection electrode are semicircular electrodes obtained by dividing a circular electrode into a straight line at the center. The gist of the invention is a liquid level deterioration detection device according to the first aspect.

The present invention exemplifies the shapes of the level detecting electrode and the deterioration detecting electrode. With this shape,
Ultrasonic waves suitable for measurement can be generated independently. (3) In the invention according to claim 3, the level detection electrode and the deterioration detection electrode are obtained by dividing a circular electrode by a concentric circle.
The gist of the liquid level deterioration detecting device according to claim 1, wherein the liquid level deterioration detecting device is a circular electrode and a ring-shaped electrode, respectively.

The present invention exemplifies the shapes of the level detecting electrode and the deterioration detecting electrode. With this shape,
By applying a similar voltage, similar ultrasonic waves can be generated. (4) The invention according to claim 4 is characterized in that, on the liquid side of the diaphragm, a reflecting portion for reflecting ultrasonic waves generated by applying a voltage between the deterioration detection electrode and the transmission side electrode is provided. The liquid level deterioration detecting device according to any one of claims 1 to 3, wherein the device is provided at a position corresponding to the deterioration detecting electrode in a sound wave transmission direction.

Therefore, by receiving the ultrasonic wave reflected by the reflecting section, it is possible to detect the deterioration of the liquid from the state of the received wave. (5) The liquid level deterioration detecting device according to the above (4), wherein the transmitting and receiving direction of the ultrasonic wave by the vibrator is substantially perpendicular to the surface of the liquid. Make a summary.

The present invention exemplifies the transmitting and receiving directions of the ultrasonic wave. Here, since the reflection surface is the surface of the liquid, the ultrasonic wave is reflected on the surface of the liquid in the direction opposite to the transmission direction. In the present invention, in detecting the liquid level,
Transmit ultrasonic waves approximately perpendicular to the liquid surface to be measured,
The light is reflected on the liquid surface to receive the reflected wave. 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.

(6) The liquid level degradation detection according to claim 4, wherein the transmitting and receiving direction of the ultrasonic wave by the vibrator is substantially parallel to the surface of the liquid. The device is the gist. The present invention exemplifies the transmitting and receiving directions of the ultrasonic wave. In the present invention, the reflection surface on which the ultrasonic wave is reflected is substantially perpendicular to the surface of the liquid, such as the wall surface of a container for storing the liquid. Therefore, the ultrasonic wave is reflected on the reflection surface in a direction opposite to the transmission direction.

Thus, a change in the liquid level can be easily detected by judging whether or not a certain standard (constant value) is satisfied. (7) The invention according to claim 7, wherein the region separating section is configured to divide the liquid-side regions of the vibration plate corresponding to between the deterioration detection electrode and the level detection electrode into the vibration plate. The liquid level deterioration detection device according to any one of claims 1 to 6, wherein the liquid level deterioration detection device is a flat plate-shaped separation plate positioned perpendicularly to the separation plate.

The present invention exemplifies the configuration of the area separating section. In the present invention, since each region is divided by the separation plate, the region on the liquid side can be surely separated,
There is an advantage that the configuration is simple. (8) The invention according to claim 8, wherein the piezoelectric element bonded to the vibration plate is an integral element, and the level detection electrode and the deterioration detection electrode are provided on the opposite side of the piezoelectric element from the vibration plate. Characterized in that they are electrically separated from each other.
The gist is the liquid level deterioration detection device according to any one of 7 above.

The present invention exemplifies the configuration of the sensor element. In the present invention, one vibrator is formed by joining one piezoelectric element to one diaphragm, and a level detecting electrode and a deterioration detecting electrode are provided on the piezoelectric element so as to be electrically separated. ing. In this case, there is an advantage that a large piezoelectric element can be used for sensor elements (vibrators) of the same size.

(9) In a ninth aspect of the present invention, the piezoelectric element bonded to the vibration plate is a separate element, and the level detection electrode is provided on a side of one of the piezoelectric elements opposite to the vibration plate. The deterioration detection electrode is provided on the other piezoelectric element on the side opposite to the vibration plate, and the level detection electrode and the deterioration detection electrode are electrically separated from each other.
The gist is the liquid level deterioration detection device according to any one of 7 above.

The present invention exemplifies the configuration of the sensor element. In the present invention, two vibrating elements are joined to one vibrating plate to form one vibrator, one of the piezoelectric elements is provided with a level detecting electrode, and the other piezoelectric element is provided with a deterioration detecting electrode. Is provided.

In this case, there is an advantage that the electrodes can be easily formed because the electrodes need only be formed on the respective piezoelectric elements, that is, it is not necessary to form the electrodes separately on one piezoelectric element. In each of the above-described inventions, the substantially vertical (or substantially horizontal) means a range of a predetermined angle θ (inclination angle) centered on the vertical (or horizontal) at which the effects of the invention can be obtained (technically substantially the same). Although it is a range that can be regarded as vertical (or almost horizontal), truly vertical (or horizontal) is desirable. Also, the inclination angle θ
Is, for example, 5 °, and within this range, the deterioration and level of the liquid can be suitably detected.

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.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment (embodiment) of a liquid level deterioration detecting apparatus according to the present invention will be described below with reference to the drawings. (Embodiment 1) Here, for example, an oil level deterioration detecting device (oil level) capable of detecting (measuring) both the level (height) of the lubricating oil (oil) of an automobile engine and the degree of oil deterioration. Deterioration sensor).

A) First, the device configuration of the oil level deterioration detection device of the present embodiment will be described. As shown in FIG.
The oil level deterioration detecting device 1 includes an ultrasonic sensor 7 at the bottom 5 of the container 3 containing oil as a sensor configuration for transmitting and receiving ultrasonic waves.

This ultrasonic sensor 7 has a single disk-shaped piezoelectric element 11 joined to the inside of a bottomed cylindrical member 9 which is cylindrical and closed on the oil side. It is arranged so that its axial direction is perpendicular to the liquid surface so that ultrasonic waves can be transmitted and received perpendicularly to the reflecting plate 27a.

Thus, the ultrasonic sensor 7 transmits ultrasonic waves into the oil, receives the ultrasonic waves reflected by the liquid surface or the reflection plate 27a, and adjusts the respective reception levels. To detect. 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 a diaphragm 15 which is
The vibrating plate 15 is provided such that its periphery is joined to the side portion 13 by brazing or the like to be integrated, and one surface (upper side in the figure) is in contact with the liquid. Note that this diaphragm 15
Is a disk having a diameter of about 18 mm and a thickness of 0.2 mm, for example.

A piezoelectric element 11 is bonded to the other surface (below the drawing) of the vibrating plate 15 which does not come into contact with the liquid by an adhesive or the like while maintaining conduction with the vibrating plate 15. A transmitting electrode 17 made of platinum is provided on the diaphragm 15 side of the piezoelectric element 11, and a pair of signal-side electrodes 19 (degradation detecting electrodes 19) also made of platinum are provided on the opposite side (the lower part of the figure).
a, a level detection electrode 19b) is provided.

The vibrating plate 15 and the piezoelectric element 11 joined together are called a vibrator 20, and each of the pair of signal-side electrodes 19 (deterioration detecting electrode 19a and level detecting electrode 19b) of the piezoelectric element 11 is connected to each other. When an electric signal (voltage) is input (applied) between the transmitting side electrode 17 and the transmitting side electrode 17, a potential difference is generated between both ends of the piezoelectric element 11, and the piezoelectric element 11 is vibrated (excited). Ultrasonic waves are transmitted through the oil.

In particular, in this embodiment, as shown in FIG. 3, the transmitting electrode 17 provided on the vibration plate 15 side of the piezoelectric element 11 is provided.
Is a disk shape, but the deterioration detection electrode 19a and the level detection electrode 19b provided on the opposite sides are semicircular shapes obtained by cutting a circle at the center. That is, the deterioration detection electrode 1
9a and the level detection electrode 19b are connected to the strip-shaped band 11
It is electrically separated at a and is symmetrical.

Also, as shown in FIG.
The first lead 21 is connected to 9a, the second lead 23 is connected to the level detection electrode 19b,
The third lead 25 is connected to the side portion 13 that is electrically connected to the third lead 25. When transmitting an ultrasonic wave, the transmitting-side electrode 1
An alternating current (alternating voltage) such as a sine wave is applied between the electrode 7 and the deterioration detection electrode 19a or between the transmission side electrode 17 and the level detection electrode 19b.

Further, in this embodiment, a reflector 27 for reflecting ultrasonic waves is provided on the liquid side (upper side in the figure) of the diaphragm 15, and this reflector 27 is composed of a reflector 27a and a support 27b. And an area separating plate 27c. this house,
As shown in FIG. 4, the reflecting plate 27a is located at a distance of 30 mm from the diaphragm 15 to reflect the ultrasonic waves.
5 is a flat plate made of stainless steel arranged in parallel with 5, and has a similar shape corresponding to the deterioration detection electrode 19a, that is, a semicircular shape in which the deterioration detection electrode 19a is translated in the liquid surface direction. is there.

The supporting portion 27b has a semi-cylindrical shape obtained by cutting a cylinder in the axial direction, and connects the end of the reflecting plate 27 on the arc side to the outer peripheral surface of the side portion 13 so as to connect to the diaphragm. Fifteen
Is located perpendicular to. The region separation plate 27c is
The vibration plate 1 is arranged so as to cover the lateral opening side of the support portion 27b.
5, a reflecting plate 27a
And the both ends of the support portion 27b. Oil enters and exits between the end of the region separating plate 27c on the diaphragm 15 side in the axial direction (downward in the figure) and the diaphragm 15, and near the end on the reflective plate 27a side in the axial direction. If possible, slit-like gap 2
9 and 35 are provided.

Therefore, the oil on the diaphragm 15 is divided into two regions by the region separating plate 27c. That is, as shown in FIG. 2, the space above the deterioration detection electrode 19a, that is, the region between the diaphragm 15 and the reflection plate 27 (first region).
The region A) and the other space (the second region B) are separated except for slight slit-like gaps 29 and 35.

Thus, as described later, a predetermined voltage is applied between the deterioration detecting electrode 19a and the transmission side electrode 17 in order to detect the deterioration of the oil, so that the When transmitting and receiving a sound wave, it is possible to prevent the ultrasonic wave from spreading to the second area B, and to apply a predetermined voltage between the level detection electrode 19b and the transmission side electrode 17 for the purpose of detecting the oil level. When ultrasonic waves are transmitted and received in the second region B by applying the voltage, it is possible to prevent the ultrasonic waves from spreading to the first region A.

In addition to the above configuration, as shown in FIG.
A temperature sensor 31 is arranged on the side portion 13 such that a part of the temperature sensor 31 is in contact with the oil, and the temperature sensor 31 measures the temperature of the oil. And the ultrasonic sensor 7
The temperature sensor 31 is connected to an electronic control unit (ECU) 33 mainly including a microcomputer 43e (see FIG. 5).

In the case of the present embodiment, the allowable range of the deviation (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, the electrical configuration of the oil level deterioration detection device 1 will be described. As shown in FIG. 5, the ECU 33 includes a signal generator 41 and a signal processor 43.

The signal generating section 41 receives a measurement start signal for measuring oil deterioration and level and generates a pulse to the ultrasonic sensor 7 and a signal from the pulse generating circuit 41a. , A reset circuit 41b that outputs a reset signal, a first delay circuit 41c that outputs a delay pulse 1, and a second delay circuit 41d that outputs a delay pulse 2.

On the other hand, the signal processing unit 43 applies the predetermined voltage between the deterioration detection electrode 19a and the transmission side electrode 17, thereby transmitting the first reflected wave when transmitting the ultrasonic wave toward the reflection plate 27a. , A first peak hold circuit 43a that holds the peak of the first received wave voltage V1 indicating the reception intensity of the first reflected wave (first received wave), and the second reflected wave (second reflected wave) that is the second reflected wave. Second received wave voltage V indicating the received intensity of received wave)
2nd peak hold circuit 43b which holds the peak of 2
And a threshold voltage section 43c for generating a threshold voltage, and a first voltage after transmitting an ultrasonic wave toward the liquid surface by applying a predetermined voltage between the level detection electrode 19b and the transmission side electrode 17. A comparison circuit 43d for comparing a voltage based on the received wave (first reflected wave) with a threshold voltage, a microcomputer 43e, and an output circuit 43f.

As will be described in detail later, the microcomputer 43e has a function of measuring the reflection time from the transmitted wave to the first received wave, and a function of measuring the peak-held values V1 and V2 of the first and second received wave voltages. In addition to having a function of determining the ratio V2 / V1, it has a function of detecting the oil level from the reflection time and a function of detecting the degree of oil deterioration from the ratio V2 / V1 of the two voltages.

In this case, the detection of the oil level and the deterioration is performed by the microcomputer 43e. Separately, the microcomputer 43e calculates the reflection time and the ratio V2 / V1 of the two voltages V1, V2, The result may be output from the output circuit 43f, and the oil level or deterioration may be detected by another microcomputer or the like.

C) Next, a method of detecting oil deterioration by the oil level deterioration detecting device 1 will be described. First, the principle by which deterioration of oil can be detected will be described. As shown in FIG. 6A, when the oil has not deteriorated,
When an ultrasonic wave is transmitted to the oil, the second reception level B1 (voltage V2) is attenuated by the second reflection wave generated after the first reflection wave with respect to the first reception level A1 (voltage V1) by the first reflection wave. The degree of is small. That is, the extent to which the amplitude of the received signal is small is small.

On the other hand, as shown in FIG. 6B, when the oil is deteriorated, when the ultrasonic wave is transmitted to the oil, compared with the case where the oil is not deteriorated, the first reflected wave is generated. The degree of attenuation of the second reception level B2 due to the second reflection wave generated after the first reflection wave is greater than the first reception level A2. That is, the degree to which the amplitude of the received signal is small is large. Therefore, in this case, B1 / A1>
B2 / A2.

Moreover, the degree of attenuation of the reception level is as follows.
Since the degree of deterioration corresponds to the degree of deterioration of the level, the degree of attenuation of the second reception level with respect to the first reception level is detected, and the detection result is referred to, for example, a map shown in FIG. Can be detected.

FIG. 7 is a graph of the data of Table 2 below, which is an experimental result under the durability test conditions of Table 1 below, that is, a graph showing the relationship between the engine operating time and the degree of attenuation of the reception level. is there. Therefore, from this graph,
The degree of oil degradation (correlated with engine operating time) can be estimated.

[0048]

[Table 1]

[0049]

[Table 2]

Next, a basic operation for detecting deterioration of oil will be described. In the oil level deterioration detection device 1 of the present embodiment, when oil deterioration is detected, a voltage is applied from the pulse generation circuit 41a to the piezoelectric element 11 constituting the ultrasonic sensor 7. That is, between the first lead 21 and the third lead 25 (that is, the deterioration detecting electrode 19).
a between the piezoelectric element 11 and the transmitting electrode 17).
5 transmits (transmits) an ultrasonic wave (transmission wave).

FIG. 8 shows the voltage waveform of the ultrasonic sensor 7 at the time of the transmitted wave, that is, the sensor output voltage, and it can be seen that the voltage waveform has a large amplitude. Also,
The transmitted ultrasonic wave travels through the oil in the first area A and is reflected by the reflection plate 27a, so that the reflected wave is received by the piezoelectric element 11 via the vibration plate 15 (see FIG. 2). 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.

FIG. 8 shows a change in voltage due to the reflected wave. It can be seen that a slightly large voltage is generated at the time of reception. More specifically, the ultrasonic sensor 7 generates a first reception level voltage (A = V1) having a smaller amplitude than the transmission wave due to the first reflection wave (first reception wave) which is the first reflection wave.
Next, the second reflected wave (that is, the first reflected wave is
The second reflected wave (second received wave), which is a reflected wave reflected by the liquid surface (reflected wave reflected by the liquid surface), causes a voltage at the second reception level (B = V2) having a smaller amplitude than the first transmitted wave. Occurs.

Therefore, the degree of oil deterioration can be detected by using both reception levels V1 and V2 as described later. Next, a method for detecting the degree of oil deterioration will be described in detail along a time series.

As shown in FIG. 8, when a pulse is output from the pulse generation circuit 41a in response to the input of the measurement start signal for measuring the deterioration of the oil to the ECU 33, the pulse causes the reset circuit 41b to output the pulse from the reset circuit 41b. A reset signal is output to the first and second peak hold circuits 43a and 43b.

The first and second peak hold circuits 43a,
43b, upon receiving the reset signal, resets the held voltage value. When a pulse is output from the pulse generation circuit 41a, a voltage is applied between the deterioration detection electrode 19a and the transmission side electrode 17, and the ultrasonic sensor 7
Then, the first and second received waves of the ultrasonic wave are sequentially detected. Note that the interval between the transmitted wave, the first received wave, and the second received wave is determined by the distance to the reflector 27a.

Further, when a pulse is output from the pulse generation circuit 41a, the delay pulse 1 is output from the first delay circuit 41c to the first peak hold circuit 41a in synchronization with the output of the reset signal, and the second pulse is output. Delay pulse 2 is output from delay circuit 41d to second peak hold circuit 43b.

Of these, the delay pulse 1 is set so as not to hold the transmitted wave at the peak, so that the first peak hold circuit 43a turns off the delayed pulse 1 after the transmission wave ends and receives the signal thereafter. The peak V1 of the first received wave is held. Further, since the delay pulse 2 is set so as not to peak hold the transmission wave and the first reception wave, the second peak hold circuit 43b turns off the delay pulse 2 after the end of the first reception wave, and thereafter, And hold the peak V2 of the second received wave received.

Thereafter, before the reset signal is output again, the microcomputer 43e calculates V2 / V1. Further, the microcomputer 43e compares the value of V2 / V1 with oil deterioration data stored in advance. In particular,
In the memory of the microcomputer 43e, a map as shown in FIG. 7 indicating the relationship between the degree of attenuation of the reception level (V2 / V1) and the degree of oil deterioration is stored, and the V
The degree of oil deterioration can be determined by referring to the value of 2 / V1 in the map.

Therefore, the value measured this time (V2 / V1)
Is the same as the value (V2 / V1) of the new oil, it is understood that the oil to be measured has not deteriorated. Also, for example, the value (V2 / V1) measured this time is
The value in oil when the car travels 10,000 km (V
2 / V1), it can be understood that the oil to be measured is equivalent to the deteriorated state of the oil that has traveled about 10,000 km.

D) Next, a method for detecting the oil level will be described. The deterioration of the oil and the detection of the level are performed at different timings so that the received waves input to the ultrasonic sensor 7 can be easily distinguished. For example, after the detection of the deterioration of the oil is completed, the level is detected (or in the reverse order).

In the oil level deterioration detecting device 1 of this embodiment, when detecting the oil level, the piezoelectric element 11
The pulse generation circuit 4 for the level detection electrode 19b
A voltage is applied from 1a. That is, an alternating voltage having a fixed frequency is applied between the second lead 23 and the third lead 25 (that is, between the level detection electrode 19b and the transmission side electrode 17). An ultrasonic wave (transmission wave) is transmitted (transmitted) via the plate 15.

The transmitted ultrasonic wave travels through the oil in the second region B and is reflected at the liquid surface. The reflected wave is received by the piezoelectric element 11 via the diaphragm 15 (see FIG. 2). . 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.

FIG. 9 shows this change in voltage. It can be seen that a large voltage is generated during transmission and reception. Accordingly, the voltage of the first reception wave is determined by a certain determination value (threshold voltage), and a signal indicating the time of reception is obtained. Specifically, in the comparison circuit 43d, when the threshold value is set sufficiently smaller than the voltage of the reflected wave and sufficiently larger than the background noise, the piezoelectric element 1
When the voltage received by 1 exceeds the threshold, a determination pulse is output.

Then, the time (transmission / reception time; reflection time) T from the start timing of the transmission wave to the rise of the first determination pulse is measured. The reflection time T is a time from transmission to reception of the ultrasonic wave. Therefore, the level (distance from the surface of the diaphragm 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 based on the oil temperature measured by the temperature sensor 3 (see FIG. 2). 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 39 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.

E) Next, a method of detecting the levels in time series will be described. When a pulse is output from the pulse generation circuit 41a in response to the input of the measurement start signal for measuring the oil level to the ECU 33, the pulse causes the reset circuit 41b to output the first and second peak hold circuits 43a and 43b. , A reset signal is output.

The first and second peak hold circuits 43a,
43b, upon receiving the reset signal, resets the held voltage value. When a pulse is output from the pulse generation circuit 41a, a voltage is applied between the oil detection electrode 19b and the transmission-side electrode 17, and an ultrasonic wave is transmitted from the ultrasonic sensor 7, and thereafter, the ultrasonic wave is transmitted to the liquid surface. The first reception wave and the second reception wave reflected and detected are sequentially detected.

Further, when a pulse is output from the pulse generation circuit 41a, the first delay circuit 41c outputs a pulse from the comparison circuit 43d.
, A delay pulse 1 is output. The comparison circuit 43 receives a sensor output signal and outputs a threshold voltage from a threshold voltage unit 43c. Further, since the delay pulse 1 is set so as to be turned off between the transmitted wave and the first reception wave, the comparator 43d outputs the sensor output voltage and the threshold voltage after the delay pulse 1 is turned off. Compare with

If the result of the comparison indicates that the sensor output voltage is higher, a comparison signal (judgment pulse) is output to the microcomputer 43e. The microcomputer 43e turns off the measurement signal when the reset signal is input and turns on the measurement signal when the comparison signal is input. Therefore, the time from the on to off of the measurement signal is measured as the reflection time.

Then, this reflection time is calculated by using the above-mentioned equation (1).
To find the level. f) The present embodiment has the following effects by the above-described configuration. The oil level deterioration detection device 1 of the present embodiment is a ratio (V2 / V1) of the first reception level V1 of the first reflection wave of the transmission wave transmitted by the ultrasonic sensor 7 and the second reception level V2 of the second reflection wave. Is compared with reference data, the degree of oil deterioration can be accurately detected.

The oil level can be obtained using the reflection time from the transmission of the ultrasonic wave to the reception of the first reception wave. Further, in the present embodiment, the oil level and the deterioration can be detected by using one ultrasonic sensor 7.
There is an advantage that the device configuration can be simplified.

Particularly, in this embodiment, the signal side electrode of the piezoelectric element 11 is separated into two for deterioration detection and level detection, and a voltage is applied between the deterioration detection electrode 19a and the transmission side electrode 17. The region separating plate 27c prevents the ultrasonic wave generated by the operation and the ultrasonic wave generated by applying a voltage between the level detection electrode 19b and the transmission side electrode 17 from being transmitted / received to a region other than the target region. Is provided.

When oil deterioration is detected, an ultrasonic wave is transmitted in the first area A using the deterioration detection electrode 19a, reflected by the reflector 27a, and the reflected wave is used. When detecting deterioration of the oil and detecting the level of the oil, the ultrasonic wave is transmitted in the second region B using the level detection electrode 19b at a timing different from the deterioration of the oil. The oil is reflected on the liquid surface, and the level of oil is detected using the reflected wave.

In other words, a single compact ultrasonic sensor 7 is used for detecting oil deterioration and oil level.
When detecting the deterioration of oil and the case of detecting the oil level, the ultrasonic waves are clearly distinguished and used. Therefore, when the ultrasonic waves are received and the reception level is detected, the reflected wave (the received wave) is also used. ) Can be clearly classified without being mixed.

Therefore, using the received waves clearly separated,
This has a remarkable effect that both the detection of oil deterioration and the detection of oil level can be performed accurately. (Embodiment 2) Next, Embodiment 3 will be described.

The description of the same parts as in the first embodiment is omitted or simplified. In the present embodiment, the shape of the reflector provided on the tip side of the ultrasonic sensor and the shape of the signal side electrode provided on the piezoelectric element are different from those of the first embodiment. a) As shown in FIG. 10, the oil level deterioration detection device 51 of the present embodiment is similar to the first embodiment in that
5 is provided with an ultrasonic sensor 57 attached thereto, and an electronic control unit (ECU) 59 connected to the ultrasonic sensor 57.

The ultrasonic sensor 57 has a vibrator 63 composed of a piezoelectric element 59 and a vibrating plate 61. The vibrator 63 has an axial direction so that ultrasonic waves can be transmitted and received in a direction perpendicular to the liquid surface and the reflecting plate 81a. Are arranged in the vertical direction in the figure. A transmitting-side electrode 65 is provided on the vibration plate 61 side of the piezoelectric element 59, and a pair of signal-side electrodes 67 (a deterioration detecting electrode 67a and a level detecting electrode 67b) are provided on the opposite side (downward in the figure). Is provided.

In particular, in this embodiment, as shown in FIG. 11, the transmitting electrode 65 provided on the vibration plate 61 side of the piezoelectric element 59.
Has a disk shape, and on the opposite side, a deterioration detection electrode 67a and a level detection electrode 67b are provided concentrically. That is, the level detection electrode 67b on the center side is circular, and the periphery thereof is surrounded by the ring-shaped gap 69.
A ring-shaped deterioration detection electrode 67a is formed, and the deterioration detection electrode 67a and the level detection electrode 67b are electrically separated.

As shown in FIG. 10, the first lead 71 is connected to the deterioration detecting electrode 67a, the second lead 73 is connected to the level detecting electrode 67b,
The third lead 77 is connected to the side portion 75 that is electrically connected to the fifth lead 5. Therefore, when transmitting an ultrasonic wave, for example, an alternating current such as a sine wave (alternating current) between the transmitting side electrode 65 and the deterioration detecting electrode 67a or between the transmitting side electrode 65 and the level detecting electrode 67b. Voltage) is applied.

Further, in this embodiment, a reflector 81 for reflecting ultrasonic waves is provided on the liquid side (upper side in the figure) of the diaphragm 61. The reflector 81 is composed of a reflector 81a and a support 81b. And an area separation plate 81c. this house,
As shown in FIG. 12, the reflection plate 81a is a flat plate material arranged in parallel with the vibration plate 61 to reflect ultrasonic waves, and has a similar shape corresponding to the deterioration detection electrode 67a, that is, the deterioration detection electrode 67a. It has a ring shape as if the detection electrode 67a was moved in parallel.

The support portion 81b has a cylindrical shape and is positioned perpendicular to the diaphragm 61 so as to connect the outer peripheral end of the reflector 81a to the outer peripheral surface of the side portion 75. The region separation plate 81c is a cylindrical plate material that is disposed perpendicular to the vibration plate 61 so as to cover the opening side inside the support portion 81b, and is integrally joined to the inner peripheral end of the reflection plate 81a. .
Between the end of the region separating plate 81c on the diaphragm 61 side in the axial direction and the diaphragm 61, and the reflecting plate 8 in the axial direction.
Near the end on the 1a side, slit-like gaps 83 and 87 are provided.
Is provided.

Therefore, the area separating plate 81c provides
The space between the diaphragm 61 and the reflector 81a (corresponding to the deterioration detection electrode 67a) (the first area A) and the other space (the second area B) are separated by a slight slit-like gap 83 and Separated except for 87. In addition to the above configuration,
As shown in FIG. 10, a temperature sensor 85 is disposed on the side portion 75 such that a part of the temperature sensor 85 is in contact with the oil, and the temperature sensor 85 measures the temperature of the oil.

The ultrasonic sensor 57 and the temperature sensor 85 are a microcomputer (microcomputer) (FIG. 5).
) As a main part, and is connected to an electronic control unit (ECU) 59 similar to that of the first embodiment. b) The operation of the oil level deterioration detection device 51 of this embodiment is the same as that of the first embodiment.

Therefore, when detecting the deterioration of the oil, an alternating voltage is applied between the transmission side electrode 65 and the deterioration detecting electrode 67a, so that the oil in the first area A is superposed from the diaphragm 61 on the oil. Transmit sound waves. Then, in the first area A,
The ultrasonic wave is reflected by the reflection plate 81a, and the deterioration of the oil is detected using the reception level of the reflected wave.

When the oil level is detected, an alternating voltage is applied between the transmitting side electrode 65 and the level detecting electrode 67b, and the oil in the second region B Transmit sound waves. Then, in the second area A, the ultrasonic wave is reflected from the oil level, the reflection time of the reflected wave is measured, and the oil level is detected.

In this embodiment, the same effects as in the first embodiment can be obtained. Third Embodiment Next, a third embodiment will be described. The description of the same parts as those in the first embodiment will be omitted or simplified.

This embodiment is different from the first embodiment in that the ultrasonic sensor has two piezoelectric elements. FIG.
As shown in (a), the sensor configuration of the oil level deterioration detection device of this embodiment is the same as that of the first embodiment, except that the ultrasonic sensor 91 attached to the bottom of the oil-filled container is used.
It has.

As in the first embodiment, the ultrasonic sensor 91 includes a bottomed cylindrical member 97 including a diaphragm 93 and a side portion 95, and reflects light so as to cover an upper half of the diaphragm 93. Plate 99a, support part 99b, area separation plate 99c
Is provided.

Particularly, in this embodiment, the pair of piezoelectric elements 10
1 (first piezoelectric element 101a, second piezoelectric element 101b) is joined to the inside of the diaphragm (below the figure). The shape of the two piezoelectric elements 101 is a semicircular shape as shown in FIG. 13B, and is arranged symmetrically.

One of the first piezoelectric elements 101a has a first transmitting electrode 103a on the diaphragm 93 side and a deterioration detecting electrode 105a on the opposite side to the diaphragm 93.
The first lead 107 is connected to the deterioration detection electrode 105a. The other second piezoelectric element 101b has a second transmitting side electrode 103b on the diaphragm 93 side.
And a deterioration detection electrode 105b on the side opposite to the diaphragm 93.
Is connected to the second lead 109.

The side portion 95 of the bottomed tubular member 97 has a third
The lead 111 is connected, and the third lead 111 is connected to the first and second transmitting electrodes 103 via the bottomed tubular member 97.
a and 103b are secured. (Embodiment 4) Next, Embodiment 4 will be described.

The description of the same parts as in the first embodiment is omitted or simplified. This embodiment differs from the first embodiment in the mounting position of the ultrasonic sensor. As shown in FIG. 14, the oil level deterioration detection device 121 of this embodiment
An ultrasonic sensor 129 having one piezoelectric element 127 and the like and having the same configuration as that of the first embodiment is attached to one side wall 125 of a container 123 containing oil.

That is, the ultrasonic sensor 129 is arranged with its axial center oriented in the horizontal direction (the direction parallel to the liquid surface) in FIG. Therefore, when oil deterioration is detected, a predetermined voltage is applied between the transmission-side electrode 131 and the deterioration detection electrode 133a, so that the ultrasonic sensor 1
The ultrasonic wave transmitted from the vibrator 135 is transmitted to the left in FIG. 14 (and thus substantially parallel to the liquid surface),
The light is reflected by the reflector 137a of the reflector 137, and the reflected wave proceeds to the right in the drawing and is received by the diaphragm 135.

When the oil level is detected, a predetermined voltage is applied between the transmitting side electrode 131 and the level detecting electrode 133b, so that the ultrasonic sensor 1 detects the oil level.
The ultrasonic wave transmitted from 29 is transmitted to the left in FIG.
Reflected at 39, the reflected wave proceeds to the right in the figure and is received by the diaphragm 135.

In this embodiment, the allowable range of the deviation (tilt angle θ) of the axial center of the vibrator 141 including the vibrating plate 135 and the piezoelectric element 127 is within 5 ° from the axial center perpendicular to the side wall 125. is there. Also in the case of the present embodiment, similarly to the first embodiment, the first reception level of the first reflected wave and the second reception level of the second reflected wave
Oil deterioration can be detected from the reception level ratio.

Further, in this embodiment, whether the oil level is above or below the ultrasonic sensor 129 (in other words, whether or not the oil level satisfies a certain value) is determined from transmission to reception of the ultrasonic wave. Since the reflection time T is different, the oil level can be detected by calculating the reflection time T.

The present invention is, of course, not limited to the above-described embodiment, but can be implemented in various modes within the scope of the present invention. For example, the liquid to be measured is not limited to the lubricating oil of an automobile engine, but can be applied to paint and the like.

Further, the transmitting side electrode provided on the diaphragm side of the piezoelectric element may be formed in a divided form corresponding to the shape of the level detecting electrode and the deterioration detecting electrode which are divided into two. . Further, in each of the above embodiments, when detecting the oil level, the level D is calculated by the following equation (1).
Is calculated.

D = (１ ／) T · Sp (1) where Sp is the speed of sound in oil. In each of the above embodiments, for the sound speed Sp, a map indicating the relationship between the oil temperature measured by the temperature sensor and the sound speed is provided in advance, and the level D is calculated using the sound speed Sp derived from this map. However, the sound speed Sp can be determined by the following method.

That is, utilizing the fact that the distance of the reflector in the reflector is always set to be constant from the diaphragm, the sound velocity is obtained by measuring the time from transmission of the ultrasonic wave to the reflector to reflection. This is a technique for reflecting this in the above equation (1). In measuring the time from the transmission of the ultrasonic wave to the reflector to the reception of the ultrasonic wave, the deterioration measurement unit of the ECU may be provided with a level measurement unit (measurement circuit) for determining the speed of sound. .

[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 oil level deterioration detection device according to the first embodiment.

FIG. 3 shows the shape of an electrode of the oil level deterioration detection device according to the first embodiment, where (a) is a plan view showing a transmitting electrode;
(B) is a plan view showing a signal side electrode.

FIG. 4 is a perspective view illustrating a reflection unit of the oil level deterioration detection device according to the first embodiment.

FIG. 5 is a block diagram illustrating an electrical configuration of the oil deterioration detection device according to the first embodiment.

FIG. 6 is an explanatory diagram showing the magnitude of the amplitude of the transmitted wave and the reflected wave of the ultrasonic sensor.

FIG. 7 is a graph showing a relationship between a degree of attenuation of a reception level and a degree of deterioration of a liquid.

FIG. 8 is an explanatory diagram illustrating an oil deterioration detection (measurement) method according to the first embodiment.

FIG. 9 is an explanatory diagram illustrating an oil level detection (measurement) method according to the first embodiment.

FIG. 10 is an explanatory diagram illustrating the entire system of the oil level deterioration detection device according to the second embodiment.

FIG. 11 shows the shape of the electrode of the oil level deterioration detection device according to the second embodiment, where (a) is a plan view showing a transmitting electrode;
(B) is a plan view showing a signal side electrode.

FIG. 12 is a perspective view illustrating a reflection unit of the oil level deterioration detection device according to the second embodiment.

13A and 13B show an ultrasonic sensor of the oil level deterioration detection device according to the third embodiment, in which FIG. 13A is an explanatory view showing the ultrasonic sensor in a broken state, and FIG. 13B is a plan view showing a piezoelectric element.

FIG. 14 is an explanatory diagram illustrating the entire system of an oil level deterioration detection device according to a fourth embodiment.

[Explanation of symbols]

1, 51, 121 ... oil level deterioration detection device 7, 57, 91, 129 ... ultrasonic sensor 11, 59, 101, 127 ... piezoelectric element 15, 61, 93, 135 ... diaphragm 17, 65, 103, 131 ... Transmission-side electrodes 19, 67 ... Signal-side electrodes 19a, 67a, 105a, 133a ... Deterioration detection electrodes 19b, 67b, 105b, 133b ... Level detection electrodes 27, 81, 99, 137 ... Reflectors 27a, 81a, 99a, 137a: Reflecting plates 27c, 81c, 99c: Area separating plates 31, 85: Temperature sensors 33, 59: Electronic control unit (ECU)

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) G01N 29/20 G01F 23/28 S (72) Inventor Hisashi Hisashi 14-18 Takatsuji-cho, Mizuho-ku, Nagoya-shi, Aichi Japan F-term (reference) in Special Ceramics Co., Ltd. (reference) 2F014 AC04 FB01 2G047 AA01 BA03 BC02 BC03 CA01 EA10 EA14 GA13 GB03 GG24 GG28 3G015 BL07 CA07 EA29

Claims (9)

[Claims] At least one surface of a vibrator formed by joining a vibrating plate and a piezoelectric element is brought into contact with a liquid to transmit ultrasonic waves in the liquid and to reflect the ultrasonic waves. A liquid level deterioration detection device that detects a level of a liquid and a degree of deterioration of the liquid by receiving a wave, wherein the piezoelectric element includes a transmitting electrode provided on the diaphragm side, and the transmitting electrode. A signal-side electrode provided on the opposite side to
And, as the signal-side electrode, a level detection electrode that applies a voltage when detecting the level of the liquid, a deterioration detection electrode that applies a voltage when detecting the degree of deterioration of the liquid, And an ultrasonic wave generated by applying a voltage between the level detection electrode and the transmission side electrode, and applying a voltage between the deterioration detection electrode and the transmission side electrode. A liquid level deterioration detection device, comprising: an area separation unit so that an ultrasonic wave generated by the operation is not transmitted / received to an area other than a target area. 2. The liquid level according to claim 1, wherein the level detection electrode and the deterioration detection electrode are semicircular electrodes obtained by dividing a circular electrode into a straight line at the center. Deterioration detection device. 3. The electrode according to claim 1, wherein the level detection electrode and the deterioration detection electrode are a circular electrode and a ring-shaped electrode obtained by dividing a circular electrode by a concentric circle. Liquid level deterioration detection device. 4. A reflecting portion for reflecting an ultrasonic wave generated by applying a voltage between the deterioration detection electrode and the transmission side electrode on a liquid side of the diaphragm in a transmission direction of the ultrasonic wave. 4. The liquid level deterioration detecting device according to claim 1, wherein the liquid level deterioration detecting device is provided at a position corresponding to the deterioration detecting electrode. 5. The liquid level deterioration detecting device according to claim 4, wherein the transmitting and receiving direction of the ultrasonic wave by the vibrator is substantially perpendicular to the surface of the liquid. 6. The liquid level deterioration detecting device according to claim 4, wherein a transmitting and receiving direction of the ultrasonic wave by the vibrator is substantially parallel to a surface of the liquid. 7. The area separating section is vertically positioned with respect to the diaphragm so as to divide each liquid-side area of the diaphragm corresponding to between the deterioration detection electrode and the level detection electrode. The liquid level deterioration detecting device according to any one of claims 1 to 6, wherein the separating device is a flat plate-like separating plate. 8. The piezoelectric element bonded to the vibration plate is an integral element, and the level detection electrode and the deterioration detection electrode are electrically separated on the side of the piezoelectric element opposite to the vibration plate. The liquid level deterioration detecting device according to claim 1, wherein the liquid level deterioration detecting device is provided. 9. A piezoelectric element bonded to the vibration plate is a separate element. The level detection electrode is provided on one of the piezoelectric elements on the side opposite to the vibration plate, and the vibration of the other piezoelectric element is provided. The liquid level according to any one of claims 1 to 7, wherein the deterioration detection electrode is provided on a side opposite to a plate, and the level detection electrode and the deterioration detection electrode are electrically separated. Deterioration detection device.