JPS6027938Y2 - Liquid level detection device - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to a liquid level detection device for detecting a liquid to be measured, such as engine oil or torque converter oil, in an automobile at two or more force points.

Conventional technology This type of device for automobiles uses multiple floats that move according to changes in the level of the liquid to be measured in order to prevent false detection due to changes in the level of the liquid to be measured due to slopes, vibrations, etc. In addition, a variable resistor is installed to respond to each float, and the level of the liquid to be measured is detected based on the threat resistance value in which the variable resistors are electrically connected in series. No. 49-155824 (see Utility Model Application Publication No. 51-80158)).

Problems that the invention aims to solve In the conventional device described above, mechanical components such as a float and a variable resistor are complex and bulky, making it difficult to reduce the size and weight of the device, and When installing the float, there were problems such as the need to consider the direction of the float so that it could move.

Furthermore, in the conventional device, in order to detect the threat resistance values of the two variable resistors, an electric circuit is connected to the one corresponding to the position of the detection liquid level.
Two operating points had to be preset, and adjustments were required on the electrical circuit to detect the desired liquid level.

The present invention solves the above-mentioned problems of the conventional device and provides a liquid level detection device that can be made smaller and lighter, does not require consideration of the direction of installation, and does not require adjustment on the electric circuit. The purpose is to

Means for Solving the Problems Therefore, the present invention disposes a plurality of oscillators connected in series at a predetermined detection liquid surface position in the liquid to be measured so as to constitute a part of an oscillation circuit. The electric circuit detects that the generation and stop of the oscillation output change in response to the immersion state of the vibrator.
a smoothing circuit that converts the oscillation output of the oscillation circuit into a voltage signal;
A switching circuit that performs a switching operation based on a preset value of the smoothing circuit is configured.

Effects of the Invention Since the present invention is configured as described above, only the necessary number of vibrators are required to be attached to the liquid container to be measured, and therefore there is no need to consider the direction when attaching, and the device can be made smaller and smaller. It has the advantage of being lightweight, and in electrical circuits, it is necessary to set a set value corresponding to the liquid level in order to detect changes in the generation and stop of the oscillation output of the oscillation circuit in response to the immersion state of the vibrator. There is no need to set it in the circuit configuration, and adjustment is easy.

In the detection device of the present invention, since adjustment is determined by the attachment of the vibrator to the liquid container to be measured, no means for adjusting the liquid level position is required in the electric circuit.

Furthermore, since a smoothing circuit is provided in the electric circuit, even if the output of the oscillation circuit has undesirable minute fluctuations,
This can be absorbed to prevent the device from making false detections.

Example The present invention will be described below with reference to the illustrated embodiments.

FIG. 1 shows the overall configuration of the device of the present invention.
Reference numeral 102 denotes a vibrator for detecting the liquid level. In this embodiment, two vibrators whose natural vibration frequency ranges are approximately the same are connected in series, and in addition to the vibrating side 101 and 102, a capacitor 11 is connected.
1 and 113, resistors 112 and 115, transistor 114
The oscillation circuit 100 is configured by:

The oscillation signal of this oscillation circuit 100 is generated by capacitors 116 and 1.
19, the voltage signal is converted into a voltage signal by the smoothing circuit 200 from the diodes 117 and 119 and the diodes 117 and 118, and drives the transistor 121 forming the switching circuit 300.

120 and 122 are resistors, a and C are power supply terminals, and b is an output terminal that outputs a detection signal.

FIGS. 2A and 2B are a front view and a cross-sectional view showing the structure of the specific installation of the vibrators 101 and 102 forming the sensor section in FIG. 1 showing the device of the present invention. In this case, only one vibrator is arranged via a lead wire, and the circuit elements of the subsequent circuit are arranged at a position apart from the main body of the sensor.

In this figure, reference numeral 10 denotes a housing, which is provided with a threaded portion 10a and a liquid communication hole 10b for attachment to the detection portion (position) of the liquid container to be measured.

The vibrator 101 is made of, for example, barium titanate or crystal.

Lead wires 11 and 12 are connected to lead wires 13 and 14, respectively, and connect the electrodes of the vibrator 101 to the circuit section 2 to be detected.
It is connected to the oscillation circuit 100 in 0 as one oscillation element.

15 and 16 are the lead wires 13 and 14 and the housing 10.
These insulators 15 and 16 also act as a seal to prevent liquid from entering the cavity 10c.

17 is a rubber cap.

3 and 4 show a state in which the sensor body of the device of the present invention shown in FIG. 2 is attached to two opposing locations on the side wall of the liquid to be measured container 30 in a container containing the liquid to be measured. In particular, FIG. 3 shows the state when the container is horizontal, and FIG. 4 shows the state when the container is tilted.

In the above configuration, as shown in FIG.
When the sensor main bodies 10-1 and 10-2 are insufficient, both vibrators 101 and 102 of the sensor bodies 10-1 and 10-2 are exposed to the air.

Therefore, the oscillation circuit 100 in the detection circuit section 20
An oscillation signal corresponding to the natural frequency of 01 and 102 is generated.

This oscillation signal is converted into a voltage signal by a smoothing circuit 200,
When this voltage reaches a predetermined value, transistor 121 is turned on.

Therefore, a voltage Q (Volt) appears at the output terminal, indicating a state where the liquid amount is insufficient.

Next, if there is enough liquid 40 to be measured, such as level 2,
Both vibrators 101 and 102 are immersed in the liquid.

As a result, the surface condition of the two members used for the oscillation operation of the oscillation circuit changes, and the Q values of these oscillators also change, causing the oscillation circuit 100 to stop oscillating.

Therefore, since the output voltage of the smoothing circuit disappears at the base potential of the transistor 121, the transistor 121 enters a cut-off state.

Therefore, a voltage equal to the power supply voltage appears at the output terminal, indicating that there is a sufficient amount of liquid.

Next, as shown in FIG. 4, for example, when the container 30 is tilted by an angle θ with respect to the horizontal plane while the car is driving on a slope, the vibrator 101 of one sensor body is exposed to the air. On the other hand, 102 is in the liquid.

Here, if the oscillation circuit 100 is set to perform oscillation operation in response to a change in Q only when the two vibrators of the two sensors are both in the air, false detection due to chattering of the liquid 40 can be avoided. It can be prevented.

Of course, the oscillation circuit can be adjusted so that oscillation occurs when one of the oscillators is exposed to air.

The liquid level detection result can be displayed by driving a display circuit (not shown) using the signal from the above-mentioned output terminal, or it can be input to another control circuit to display the result according to the liquid level state. It is also possible to control other devices.

In the above embodiment, the configuration of the oscillation circuit 100 is not limited to the embodiment, and the resistor 115 of the oscillation circuit 100
If a series circuit of a resistor and a coil is connected instead, the amplitude of the oscillation signal can be made larger.

Further, as shown in FIG. 5, the sensor main body 1G-1°10-2 is preferably disposed diagonally at 45° with respect to the traveling direction of the vehicle in the case of detecting the liquid level in a vehicle loading container.

[Brief explanation of the drawing]

Figure 1 is an electrical wiring diagram showing an embodiment of the present invention, Figure 2A
, B is a front view and a cross-sectional view of the sensor body used to detect the amount of liquid to be measured, FIGS. 3 and 4 are cross-sectional views to explain the operation, and FIG. 5 is an explanation showing the mounting position of the sensor body. It is a diagram. 101.102... Vibrator, 100...
・Oscillation circuit, 200...Smoothing circuit, 300...
...Switching circuit.

Claims (1)

[Claims for Utility Model Registration] A detecting body in which a plurality of vibrators are arranged at a predetermined detection liquid surface position in a liquid to be measured and the plurality of vibrators are connected in series, and the plurality of vibrators of the detecting body. an oscillation circuit that generates or stops oscillation output depending on the immersion state of the vibrator, a smoothing circuit that converts the oscillation output between the oscillations into a voltage signal, and a switching operation based on a preset value of the smoothing circuit. A liquid level detection device comprising: a switching circuit for detecting