JPH0621666B2 - Equipment for removing foreign matter from static mechanical seals - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an apparatus for preventing an abnormal occurrence of a mechanical seal due to the accumulation of foreign matter in a static mechanical seal in which a driven ring is non-rotating.

[Conventional technology]

Mechanical seals that seal the shafts of rotating equipment include static mechanical seals and rotary mechanical seals.

Among them, in the static mechanical seal, a driven ring pressed by a spring is supported by a housing on the stationary side, and a seat ring slidingly contacting the driven ring is fixed to a rotary shaft.

However, in the static mechanical seal, when the liquid to be sealed contains foreign matter, when the foreign matter accumulates on the spring or the like pressing the driven ring toward the rotating seat ring and hardens. However, the followability of the driven ring with respect to the displacement of the seat ring is deteriorated, and a large amount of leakage may be induced.

[Problems to be Solved by the Invention]

In most cases, such an abnormality of the mechanical seal is not discovered until a large amount of leakage has occurred, and foreign matter accumulated on the spring etc. is removed before a large amount of leakage accident occurs. A device that eliminates abnormal conditions by
It does not currently exist.

Therefore, the present invention has been made to prevent the occurrence of a leakage accident of a static mechanical seal due to the accumulation of foreign matter in the fluid to be sealed.

[Means for Solving the Problems]

In order to solve the above-mentioned problems, the apparatus for removing accumulated foreign matter of a static mechanical seal according to a first aspect of the present invention is a stationary side of a static mechanical seal, and rotates a non-rotating driven ring of the mechanical seal. A vibrator for performing mutual conversion between mechanical energy and electric energy is provided at a position where a spring pressed against the seat ring is backed up, and a display unit for displaying an output voltage from the vibrator outside the mechanical seal and an AC power supply unit. The display unit and the AC power source unit are selectively connected to the vibrator through a switching circuit, and the foreign matter is removed from the stationary mechanical seal according to the second aspect of the invention. The device includes a control device that issues an operation command when the output voltage from the vibrator becomes a certain value or less, and an AC power supply unit. The current supply unit is selectively connected to the vibrator via a switching circuit, and the switching circuit switches the connection from the control device side to the AC power supply unit side for a predetermined time according to an operation command from the control device. It is configured.

[Action]

When the operating condition of the static mechanical seal is normal, the non-rotating driven ring follows the delicate axial behavior of the seat ring due to rotation, and vibrates slightly. However, when the follow-up operation is hindered by the accumulation of foreign matter on the spring or the like that presses the driven ring against the seat ring, the minute vibration is gradually reduced.

The present invention has been made paying attention to this fact. When mechanical energy (vibration) is applied, electric energy (AC voltage) corresponding to the mechanical energy is generated, and when an electric field is applied, mechanical energy corresponding to the electric energy is generated. The oscillator is used as a sensor, and normally this oscillator is made to function as a sensor, and the presence or absence of abnormality due to the accumulation of foreign matter is determined by electrically detecting the microvibration. It is characterized in that an AC voltage is applied to the vibrator to vibrate and the deposited foreign matter is removed by the vibration.

That is, in the deposited foreign matter removing device according to the first aspect of the present invention, when the output voltage from the vibrator displayed on the display unit becomes equal to or lower than a certain value, the switching circuit is operated to apply an alternating current to the vibrator. Apply AC voltage from the power supply. In addition, the deposited foreign matter removing device according to the second aspect operates the switching circuit as follows.
It is designed to be performed by a control device.

〔Example〕

 Hereinafter, the device of the present invention will be described based on the illustrated embodiment.

First, in the embodiment shown in FIG. 1, (1) is a static mechanical seal attached to a pump, which is a metal case (5) fixed to an opening of a shaft hole of a pump housing (8).
A non-rotating driven ring (2), a spring (3) axially pressing the driven ring (2), and a rubber bellows (sealing between the metal case (5) and the driven ring (2). 4) and the like are incorporated, and on the other hand, the seat ring on the rotating side is inserted into the inner diameter portion of the impeller (10) that is fixed to the shaft end of the rotating shaft (9) and rotates, via the gasket (7) made of a rubber material. (6) is incorporated, the driven ring (2) is pressed against the seat ring (6) by the spring (3), and both rings (2) and (6) slide close to each other to achieve a shaft sealing function. Run.

The driven ring (2) is pressed toward the seat ring (6) side against the inner surface of the rear end wall (5 ') of the metal case (5) which is the stationary side (non-rotating side) of the mechanical seal (1). A piezoelectric vibrator (11) made of piezoelectric ceramics (for example, BaTiO ₃ or the like) is fixed so as to receive a load due to the reaction of the spring (3). Piezoelectric ceramics forming the piezoelectric vibrator (11) is a good piezoelectric material in which a voltage corresponding to the strain is generated when an external force such as a pressure or a tension causes a strain, and conversely a strain occurs when an electric field is applied to polarize the piezoelectric ceramic. It has an effect, which enables mutual exchange of mechanical energy and electric energy. That is, in the piezoelectric vibrator (11), when the pump is driven, a slight vibration generated by the follow-up operation of the driven ring (2) with respect to the axial behavior of the seat ring (6) accompanying the rotation is applied via the spring (3). As a result, a weak AC voltage corresponding to the amplitude and frequency of this input vibration is output, and conversely, when an AC voltage is applied, vibration corresponding to this is generated.

(12) is outside the pump, that is, mechanical seal (1)
Is a display unit provided outside the device, such as a digital display circuit or an AC voltmeter. Further, (13) is an AC power supply portion also provided outside the pump, that is, outside the mechanical seal (1), which is composed of, for example, an oscillation circuit and an amplification circuit, and outputs an alternating current of a predetermined frequency and voltage.

(14) is a switching circuit for selectively connecting the piezoelectric vibrator (11) to either the display unit (12) or the AC power supply unit (13), that is, the display unit (12) is a terminal of the switching circuit (14). In (14a), the AC power supply unit (13) is connected to the terminal (14
In b), the piezoelectric vibrator (11) is connected to the terminal (14c), respectively.

In the above configuration, the piezoelectric vibrator (11) is normally connected to the display section (12) by the switching circuit (14) and functions as a sensor for detecting the operating state of the mechanical seal (1). That is, the microvibration generated by the follow-up operation of the driven ring (2) with respect to the seat ring (6) is input to the piezoelectric vibrator (11) as a subtle load fluctuation of the spring (3), so that the piezoelectric vibrator (11). ) Outputs a weak AC voltage (vibration detection signal) corresponding to the amplitude and frequency of the input vibration, and this output voltage is amplified by an amplifier circuit (not shown), measured, and displayed on the display unit (12).

If foreign matter accumulates on the spring (3) of the mechanical seal (1), the driven ring (2) with respect to the seat ring (6)
If the follow-up operation (fine vibration) of the piezoelectric vibrator (1
Since the output voltage value and the frequency from 1) become small, when the voltage measurement value displayed on the display unit (12) becomes a certain value or less, the switching circuit (14) is changed from the terminal (14a) to the terminal (14a). 14b). By this switching operation, the piezoelectric vibrator (11) is disconnected from the display unit (12) and is connected to the AC power supply unit (13), and the AC power supply unit (13) outputs an AC of a predetermined frequency and voltage. Is applied to the piezoelectric vibrator (11). That is, the piezoelectric vibrator (11) is switched from the function as a sensor to the function as an actuator at this point, vibrates due to the applied voltage, and this vibration is transmitted to the spring (3), so that the spring The foreign matter deposited and fixed on (3) is peeled off and removed. After that, by operating the switching circuit (14), the connection of the piezoelectric vibrator (11) is switched to the display unit (12) again.
It is confirmed whether the follow-up operation of the driven ring (2) has returned to the normal state.

Since the amplitude of the vibration generated in the piezoelectric vibrator (11) by the application of the AC voltage is small, the piezoelectric vibrator (11) has a structure in which a piezoelectric ceramic element and a metal bending plate are bonded together. Means for amplifying the amplitude by matching the frequency of the AC voltage output from the AC power supply unit (13) with the natural frequency of the piezoelectric vibrator (11), or the frequency of the AC voltage of the spring (3). Resonating the spring (3) according to the natural frequency, or setting the frequency of the AC voltage in a high frequency range is extremely effective in enhancing the foreign matter removing effect. However, in this case, there is no possibility that the driven ring (2) vibrates in the axial direction due to the amplitude of the spring (3) increasing more than necessary, and leakage occurs between the driven ring (2) and the seat ring (6). Thus, the applied voltage value is set appropriately.

Next, the embodiment shown in FIG. 2 has the above switching circuit (14).
The switching is controlled by the control device.

That is, (15) compares the measured value of the output voltage from the piezoelectric vibrator (11) with a preset and stored voltage value, and when the measured value becomes less than or equal to the set value, the switching circuit (14) Is a control device for driving a relay (16) for switching from a terminal (14a) to a terminal (14b) for a predetermined time, and is composed of, for example, a microcomputer having an input port, an arithmetic unit, a setting unit, an output port and the like as main elements. The input port of the control device (15) is connected to the terminal (14a) of the switching circuit (14), and the output port is connected to the relay (16). Then, as in the above-described embodiment of FIG. 1, the AC power supply unit (13) is the terminal (14b) of the switching circuit (14), and the piezoelectric vibrator (11) is the terminal of the switching circuit (14) ( 14c).

In the above configuration, the piezoelectric vibrator (11) is normally connected to the control device (15) side by the switching circuit (14), that is, the AC voltage as the detection signal output from the piezoelectric vibrator (11) is , Is input to the input port of the control device (15). Where mechanical seal (1)
Of foreign matter on the spring (3) of the driven ring (2)
When the operation of is inhibited and the measured value of the output voltage from the piezoelectric vibrator (11) becomes less than or equal to the set value, the control device (15) issues an operation command to drive the relay (16) for a predetermined time.
The switching circuit (14) switches the terminal (14a) to the terminal (14b) by driving the relay (16), that is, the connection of the piezoelectric vibrator (11) from the control device (15) side to the AC power supply unit (13). The piezoelectric vibrator (11) vibrates by the voltage applied from the AC power supply unit (13), and removes the foreign matter deposited on the spring (3). Then, after a lapse of a predetermined time, the driving of the relay (16) is stopped, the switching circuit (14) is switched to the terminal (14a) again, the piezoelectric vibrator (11) functions again as a sensor, and the control device (15). To output a detection signal.

In each of the above embodiments, the piezoelectric vibrator is used as the vibrator that also serves as the sensor and the actuator, but this may be replaced with an electromagnetic vibrator that is a combination of an exciting coil and a magnet. The static mechanical seal structure is also
It is not limited to the one shown.

〔The invention's effect〕

As described above, according to the present invention, a vibrator that also serves as a sensor and an actuator is provided on the stationary side of a static mechanical seal, and an AC voltage output from the vibrator is applied to a spring that presses a driven ring. Of detecting abnormalities due to the accumulation of foreign matters, and when abnormalities are detected, reverse current is applied to the vibrator by switching the switching circuit to vibrate to remove accumulated foreign matters. The static mechanical seal can be prevented from malfunctioning and stable sealing performance can be maintained.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram showing a first embodiment of the present invention, and FIG. 2 is a schematic configuration diagram showing a second embodiment. (1) Static mechanical seal (2) Driven ring (3) Spring (5) Stationary metal case (6) Seat ring (11) Piezoelectric vibrator (12) Display section (13) AC power supply section (14) Switching Circuit (15) Control device (16) Relay

Claims (2)

[Claims] 1. A vibration which performs mutual conversion between mechanical energy and electric energy on the stationary side of a static mechanical seal and at a position where a spring for pressing a non-rotating driven ring of the mechanical seal against a rotating seat ring is backed up. A display unit for displaying the output voltage from the vibrator and an AC power supply unit are provided outside the mechanical seal, and the display unit and the AC power supply unit are selected for the vibrator via a switching circuit. Foreign matter removal device for static mechanical seals, characterized in that they are connected electrically. 2. A vibration that performs mutual conversion between mechanical energy and electric energy on the stationary side of the static mechanical seal, at a position where a spring for pressing a non-rotating driven ring of the mechanical seal against a rotating seat ring is backed up. A control device that issues a motion command when the output voltage from the vibrator is below a certain value and an AC power supply unit are provided outside the mechanical seal, and these control devices and AC power supply units are provided. A connection is selectively made to the vibrator via a switching circuit, and the switching circuit switches the connection from the control device side to the AC power supply unit side for a predetermined time according to an operation command from the control device. A stationary foreign matter removal device for mechanical seals.