JPH0215533Y2 - - Google Patents

Description

[Detailed explanation of the invention] <<Industrial application>> This invention detects when a large negative pressure is generated on the secondary side due to excessive clogging of the fluid filter element, and This invention relates to a negative pressure detector for a fluid filter.

<<Prior Art>> A well-known electric negative pressure detector for a fluid filter is disclosed in detail in, for example, Japanese Patent Publication No. 57-22610.

This conventional negative pressure detector includes a casing, a diaphragm that partitions the inside of the casing into a negative pressure chamber that communicates with the negative pressure side of a fluid filter, and an atmospheric chamber that communicates with the atmosphere, and that is attached to the diaphragm. It includes a light-shielding body that is displaced along with a diaphragm that bends in response to negative pressure in the negative pressure chamber, and a pair of a light-emitting element and a light-receiving element arranged to sandwich the light-shielding body. A photo interrupter is provided in which an optical path is formed, and the optical path is interrupted by displacement of the light shield when the negative pressure in the negative pressure chamber becomes equal to or higher than a predetermined pressure.

The configuration of the electric circuit of this negative pressure detector is shown in FIG.

In FIG. 1, 10 is a photointerrupter including a light emitting diode LED as a light emitting element and a phototransistor PT as a light receiving element, 12 is the above-mentioned light shield, and 14 and 16 are power supply/output terminals.
A DC power supply 18, a reset switch 20, and a warning lamp 22 are externally connected in series between the terminals 14 and 16. The light emitting diode LED is connected in series with the resistor R1 between terminals 14 and 16, and constantly emits light. The phototransistor PT is connected in series with the collector resistor R3 between terminals 14 and 16, and the photodetection output is taken out from its collector. Thyristor SCR is used as an output element to transmit the output of phototransistor PT to the outside.
It is connected between terminals 14 and 16. thyristor
The gate of the SCR is connected to the terminal 16 via a resistor R2, and is connected to a Zener diode.
Connected to the collector of phototransistor PT via ZD.

In the above circuit, when the negative pressure of the fluid filter is not so large and the light from the light emitting diode LED is received by the phototransistor PT and it is turned on, the collector of the phototransistor PT is at a low level, and therefore the Zener diode
ZD and SCR are cut off. In this state, the light emitting diode LED and phototransistor PT
Although a current flows through, this current is not so large that the warning lamp 22 does not substantially light up.

When the negative pressure on the secondary side of the fluid filter becomes equal to or higher than a predetermined pressure, the light shielding body 12 is displaced in the direction of the arrow, and the optical path from the light emitting diode LED to the phototransistor PT is blocked. Then, the phototransistor
PT turns off and its collector voltage goes high, which turns on the Zener diode ZD and triggers the thyristor SCR. This trigger turns on the thyristor SCR, making the terminals 14 and 16 almost short-circuited. Therefore,
A large current flows through the warning lamp 22, which lights up to notify that the filter element is clogged.

<<Problems to be solved by the invention>> As described above, in the conventional negative pressure detector, the photo interrupter 10 is used to detect the amount of deflection of the diaphragm.
and a light shield 12 are used, but if the light path is blocked by the light shield 12, and if even a small amount of light leaks, the above-mentioned warning lamp 22 will not be able to notify, so the positional relationship between these must be maintained with high precision. Not only that, but the configuration of the detection section becomes complicated, which inevitably increases the cost of the device.

≪Purpose of the invention≫ The purpose of this invention is to reduce costs by using a simpler device to detect the amount of deflection of the diaphragm, and to create a negative pressure detector for fluid filters that is almost permanently reliable. This is what we provide.

≪Means for solving the problem≫ In order to achieve the above object, the present invention uses a permanent magnet that detects negative pressure on a diaphragm, and a Hall element that is provided opposite to the moving direction of the permanent magnet. The present invention is characterized in that the warning means is activated by using an on/off voltage generated in the Hall element depending on the displacement position of the permanent magnet.

<<Embodiment>> FIG. 2 shows the structure of a negative pressure detector for a fluid filter according to an embodiment of this invention, and FIG. 3 shows its electric circuit.

In FIG. 2, the casing 30 includes a cylindrical body 32,
34 and a lid 34, this casing 3
There is a bellows-shaped diaphragm 38 in the center of the interior of 0.
is attached, and a negative pressure chamber 40 and an atmospheric chamber 42 are separated by a diaphragm 38. Negative pressure chamber 4
0 is connected to the secondary side (negative pressure side) of a fluid filter (not shown) through a port 44. Atmospheric chamber 4
2 is communicated with the atmosphere through a breathable member 46 such as felt and holes 48 in the cylinder 34.

A movable guide tube 50 is attached to the outside of the diaphragm 38, and a compression spring 52 is attached between the guide tube 50 and the bottom of the tube body 2. This compression spring 52 always urges the guide tube 50 and the diaphragm 38 upward.

A rod-shaped body 58 is attached to the center of the diaphragm 38 via a screw member 56, and a permanent magnet 60 is attached to the tip of this rod-shaped body 58. A circuit board 54 is attached to the upper end of the cylindrical body 34, and a Hall element 62 is attached to the circuit board 54 so as to face the moving direction of the permanent magnet 60. This Hall element 62 is an element that has the function of converting a magnetic signal into an electric signal.

When the negative pressure in the negative pressure chamber 40 becomes equal to or higher than the set pressure, the diaphragm 38 and the guide tube 50 are compressed by the compression spring 52.
, and along with this, the permanent magnet 6
0 is also arranged to fall downward away from the Hall element 62.

A circuit described below is configured on the circuit board 54, and also includes a pair of power terminals 24,
26 are provided, and these terminals 24, 2 are connected from the lid 36.
6 stands out.

As shown in FIG. 3, a DC power supply 18, a normally closed reset switch 20, and a warning lamp 22 as a warning means are connected in series between the power supply terminals 24 and 26. These are the external connection circuits of the detector.

Inside the detector, the VCC terminal 1 of the Hall element 62 is connected to one power supply terminal 24 via a high-voltage resistor R4, and the GND terminal 2 of the Hall element 62 is directly connected to the other power supply terminal 26. has been done. Moreover, between both power terminals 24 and 26,
Thyristor SCR is connected. The gate G of this thyristor SCR is connected to the output terminal 3 of the Hall element 62, and is also connected to the anode A via a collector resistor R5, and is further connected to the GND terminal 2 via a gate resistor R6.
It is connected to the.

In the above circuit, when the permanent magnet 60 is sufficiently close to the Hall element 62, the Hall element 62
Since a large magnetic flux density is applied, the voltage generated at the output terminal 3 of the device becomes almost equal to zero, as shown in FIG. (VCE about 0.4V) That is, in this state, the thyristor SCR is turned off and the potential of the gate G becomes 0. At this time, a spike-like voltage from an external source enters the gate G of the thyristor SCR due to the gate resistor R6.
This thyristor SCR is designed to prevent it from turning on and malfunctioning. Therefore, the warning lamp 22 is not lit in this state.

Then, when a negative pressure higher than the set pressure is detected and the permanent magnet 60 moves downward and away from the Hall element 62, the magnetic flux density acting on the Hall element 62 gradually decreases, and when it reaches a certain point, the As shown in FIG. 4, the voltage generated in the Hall element 62 increases on and off. Then, the thyristor
A current flows into the gate G of SCR via the collector resistor R5, and the thyristor SCR is turned on and fired, and the anode A of the thyristor SCR,
The potential across the cathode K becomes almost 0V, and the warning lamp 22 is lit.

Once ignited, the SCR will not be extinguished even if the permanent magnet 60 separates from the Hall element 62, but will remain ignited, and the warning lamp 22 will continue to light up.

Note that if the reset switch 20 is pressed while the permanent magnet 60 is separated from the Hall element 62, the lamp 22 goes out and is reset.

FIG. 5 shows another embodiment of this invention, in which the same components as in the previous embodiment are given the same reference numerals, and their explanation will be omitted.

That is, in this embodiment, in addition to the terminals 24 and 26, an output-only terminal 28 is further provided, and the light emitting diode 7
0 as a warning means, the anode A of the thyristor SCR is connected to a newly provided output terminal 28 without connecting the power supply terminal 24, and this output terminal 28 is connected to a light emitting diode via a current supply resistor R7. The light emitting diode 70 is further connected to the reset switch 20.

Therefore, in this embodiment, the output terminal 28
Since it is possible to create an output change completely unrelated to the power supply operation, the degree of freedom of the detection output notification load circuit connected to the output terminal is increased.

Incidentally, since the Hall element 62 can exhibit sufficient performance in a considerable voltage range, it can be used satisfactorily even if the DC power source 18 is constantly fluctuating, such as an automobile battery.

<<Effects of the invention>> As explained above, the negative pressure detector for a fluid filter according to this invention can detect changes in the deflection of the diaphragm,
In other words, since negative pressure changes in the filter are detected by a Hall element via a permanent magnet, these permanent magnets and Hall elements constitute a non-contact circuit, which, together with the lifespan of the Hall element, significantly increases the reliability of the device. will be improved.

In addition, by using a Hall element and a permanent magnet, the positional relationship between these can be determined as long as the Hall element is within the range of the magnetic force of the permanent magnet, and there is no need to set the positional relationship as strictly as in an optical type. This has various excellent effects such as simplifying the configuration and reducing costs.

[Brief explanation of drawings]

Figure 1 is a circuit diagram of a conventional negative pressure detector for a fluid filter, Figure 2 is a structural diagram of a negative pressure detector for a fluid filter according to an embodiment of the present invention, and Figure 3 is a diagram according to an embodiment of the present invention. Circuit diagram of negative pressure detector for fluid filter, Figure 4 is output voltage characteristic diagram of Hall element, Figure 5
The figure is a circuit diagram showing another embodiment of the present invention. 22...Warning lamp (warning means), 30...Casing, 38...Diaphragm, 40...Negative pressure chamber, 42...Atmospheric chamber, 60...Permanent magnet, 62...
...Hall element, 70...Light emitting diode (warning means), SCR...Thyristor.

Claims (1)

[Scope of utility model registration request] a casing; a diaphragm that partitions the inside of the casing into a negative pressure chamber communicating with the negative pressure side of the fluid filter and an atmospheric chamber communicating with the atmosphere; a permanent magnet that is displaced as the diaphragm bends; a Hall element that is mounted on the casing side facing the direction of movement of the permanent magnet; and a change in the distance between the permanent magnet and the Hall element that occurs in the Hall element. 1. A negative pressure detector for a fluid filter, comprising: a circuit for detecting a voltage change; and a warning means for sensing a voltage change of a Hall element detected by the circuit and operating to issue a warning.