RU2761769C1 - Lip seal testing device - Google Patents

Abstract

FIELD: measuring technology.

SUBSTANCE: invention is used in measuring technology, for monitoring the performance of elastomeric seals, such as lip seals. A device for testing a lip seal installed in a housing cavity filled with an electrically conductive liquid, equipped with probing electrodes protruding to the contact surface of the sleeve with a hollow shaft, connected to a power source and limiting resistors, in which for simultaneous measurement of the value of the longitudinal displacement of the contact zone along the shaft and the width of this contact, depending on the angle of rotation of the shaft relative to the cuff, probe electrodes are located in the shaft body, laid in series in a row and brought out to the shaft surface along a line approximately parallel to its axis, while the probe electrodes are connected to a power source and limiting resistors, additionally contains a second auxiliary lip seal, and the probe electrodes connected to the inputs of electronic amplifiers, the outputs of which are connected to a LED display fixed at the end of the hollow shaft to transmit the luminous flux to the receiving unit, while the electric drive is controlled from an electronic computer using a digital-to-analog converter and a power amplifier.

EFFECT: increasing the measurement accuracy by eliminating interference in the measurement information transmission circuits, which makes it possible to measure the instantaneous value of the contact width of the lip seal with the shaft, as well as the displacement of the lip seal contact along the shaft simultaneously and locally at several points around the circumference of the shaft, form graphs of dependences in time of the contact width and displacement of the lip seal at the given points of contact with the shaft.

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Description

The invention relates to the field of measuring technology and can be used to monitor the performance of elastomeric seals, such as lip seals, widely used in various fields of technology (mechanical engineering, automobile and tractor construction, aviation, etc.).

There is a known device for measuring the width of the contact of a lip seal with a shaft (SU No. 504072 A1, G01B 7/02, dated 02.25.1976), which consists of a shaft simulator made of non-conductive material, an electric current conductor attached to the cylindrical part of the shaft simulator , two electrodes, an electrolytic bath and an ohmmeter. The conductor is made in the form of a wire spiral wound with a constant pitch on the shaft simulator and is recessed by half the wire diameter, the protruding part of which is removed flush with the shaft simulator surface. The lip seal divides the electrolytic bath into two independent volumes, and at the point of its contact with the shaft simulator it isolates part of the wire from direct contact with the liquid conductor. The width of the contact between the lip seal and the shaft is judged by the ohmmeter reading, which is proportional to the length of the wire covered by the seal.

The closest in technical essence to the proposed device is a device for testing lip seals (SU No. 702204 A1, F16J 15/32, from 05.12.1979), which is a housing filled with an electrically conductive liquid. The housing contains the test and auxiliary lip seal and the hollow shaft. In the body of the shaft, probing electrodes are laid sequentially in a row, which, with their ends, are brought out to the surface of the shaft along a line parallel to its generatrix. The power supply and the measuring device are located inside the hollow shaft. The investigated lip seal isolates a part of the ends of the probing electrodes from the electrically conductive liquid. The width of the contact between the lip seal and the shaft is determined by the number of probing electrodes in contact with the electrically conductive liquid.

The disadvantages of the described devices are:

- insufficient accuracy due to analog processing of measurement information obtained in discrete form;

- the presence of interference caused by brush contacts in the measurement information transmission circuits,

- the inability to measure the instantaneous value of the contact width of the lip seal with the shaft simultaneously and locally at several points around the circumference of the shaft,

- the impossibility of automatically generating graphs of the dependences of the width or displacement of the lip seal contact along the shaft at the same time at different points of this contact on the time or shaft rotation frequency.

The technical result that can be obtained by implementing the invention consists in increasing the accuracy of measuring the contact width of the lip seal with the shaft, eliminating interference in the measurement information transmission circuits, the ability to measure the instantaneous value of the contact width of the lip seal with the shaft, as well as displacement of the contact zone along the axis shaft, simultaneously and locally at several points around the circumference of the shaft and automatically generate graphs of the dependences of the width or displacement of the contact of the lip seal with the shaft simultaneously at different points of this contact on the time or shaft rotation frequency.

The essence of the invention is achieved in that a device for testing a lip seal installed in a housing cavity filled with an electrically conductive liquid, equipped with probing electrodes protruding to the contact surface of the lip seal with a hollow shaft, connected to a power source and limiting resistors, in which for simultaneous measurement of the longitudinal displacement of the contact zone along the shaft and the width of this contact, depending on the angle of rotation of the shaft relative to the cuff, the probing electrodes are located in the body of the shaft, stacked sequentially in a row and brought out to the surface of the shaft along a line approximately parallel to its axis, while the probing electrodes are connected to a power source and limiting resistors, additionally contains a second auxiliary lip seal, and the probing electrodes are connected to the inputs of electronic amplifiers, the outputs of which are connected to an LED display mounted at the end of the hollow shaft for transmission luminous flux into the receiving unit, while the electric drive is controlled from an electronic computer using a digital-to-analog converter and a power amplifier.

The essence of the invention is illustrated by drawings.

Figure 1 shows a block diagram of the device; Fig. 2 shows the construction of the measuring unit of the device; Fig. 3 shows an LED display panel for two groups of LEDs, FIG. 4 shows the LED display board for four groups of LEDs.

The block diagram of the device contains: 1 - electric drive, 2 - measuring unit, 3 - LED indicator board, 4 - lens, 5 - matrix of charge coupled devices (CCD - matrix), 6 - analog-to-digital converter (ADC), 7 - control circuit, 8 - power amplifier (PA), 9 - digital-to-analog converter (DAC), 10 - electronic computer (PC), 11 - adjustable electric drive, 12 - receiving unit.

FIG. 2 shows the following units and details of the measuring unit of the device: 13, 16 - limiting resistors to limit the current through the probe electrodes 29, 38; 14 - clutch for communication with the electric motor 1; 15 - power supply unit for powering the electronic circuit; 17 - hollow shaft for contact with the investigated lip seal 24 and auxiliary lip seals 21, 27; 18 - sleeve bearing for fixing the hollow shaft 17 in the housing 19; 19 - housing for placement of units and parts of the measuring unit; 20, 22, 25, 28 - locating rings for fixing the investigated lip seal 24 and auxiliary lip seals 21, 27 in the housing 19; 21, 27 - auxiliary lip seals for creating cavities for electrically conductive liquid, 23, 26 - filling holes for filling electrically conductive liquid, 24 - investigated lip seal, 29, 38 - probe electrodes; 30 - housing cover; 31 - sliding bearing for fixing the hollow shaft 17 in the housing cover 30; 32, 33 - blocks of electronic amplifiers for amplifying signals from the probing electrodes 29, 38; 35 - marker LED for fixing the center of the scoreboard 37; 34, 36 - information LEDs for transmitting measurement information to the receiving unit 12; 37 - information board for placing information LEDs; An electrically conductive liquid is poured between the auxiliary lip seals 21, 27 and the test seal 24.

When the device is in operation, the signal from each probe electrode goes through 4 stages:

- conversion of an electrical signal into an optical one,

- transmission of an optical signal from the rotating shaft to the receiving unit,

- conversion of an optical signal into an electrical signal,

- formation of measurement information.

The stage of converting an electrical signal into an optical one is realized by the fact that each probe electrode is connected to the input of the corresponding electronic amplifier, and the amplifier is loaded with an LED placed on a light board attached to the end of the shaft.

The stage of transmitting the optical signal from the rotating shaft to the receiving unit is carried out by transmitting the optical signal from the LEDs located on the light board through the lens to the CCD matrix.

The stage of converting the optical signal into an electrical signal is performed by controlling the operation of the CCD matrix from the computer through the control circuit with further transmission of electrical signals from the CCD matrix to the ADC, and then to the computer for processing.

The stage of formation of measurement information is carried out by forming a database of measurement information in the computer memory with subsequent processing of these data according to a given program, depending on the objectives of the study or control. The measurement information is output to a printer or display.

The operation of the device for testing lip seals is as follows. The adjustable electric drive 11 transmits the torque to the measuring unit 2, where the test lip seal, the hollow shaft and the electronic circuit for measuring the instantaneous value of the width and displacement of the lip seal contact are located simultaneously and locally at several points along the circumference of the shaft. The circuit located inside the hollow shaft also serves to convert the instantaneous value of the width and displacement of the lip seal contact with the shaft into a discrete signal. This signal goes to the LED indicator board 3, attached to the end of the hollow shaft. The optical signal from the LEDs of this display goes through the lens 4 to the CCD matrix 5, which is controlled by the control circuit 7 using the computer 10. In the CCD matrix 5, the optical signal is converted into an electrical signal, which is fed through the ADC 6 to the computer 10 for processing and generating an output signal, depending on the goals and the study program of the lip seal.

The main functional elements of the device are: an adjustable electric drive 11, a measuring unit, an LED indicator board, a receiving unit, an electronic computer.

Variable electric drive 11 consists of a direct current drive motor 1 and a control circuit. The control circuit of the drive motor 1 includes a power amplifier 8, which feeds the armature circuit of the motor 1, as well as a digital-to-analog converter 9, which converts the digital code coming from the computer 10 into an analog signal required to control the drive motor 1. Due to the use in the drive motor 1 independent excitation, it is possible to regulate the frequency of rotation of the motor shaft over a wide range. The rotational speed of the drive motor is determined by the research objectives of the lip seal. The research program is recorded in the computer memory 10.

The design features of the measuring unit are as follows.

The hollow shaft 17 has from one to several longitudinal grooves, each of which contains one row of isolated probing electrodes 29, 38. The end parts of the probing electrodes are cut flush with the outer surface of the hollow shaft and are in contact with the investigated lip seal 24 and the liquid conductor. The number of grooves in the hollow shaft is determined by the lip seal research program. Inside the hollow shaft 17 are electronic amplifier units 32, 33 and a power supply 15. The number of electronic amplifier units is equal to the number of slots in the hollow shaft. The probing conductors are connected to the inputs of the electronic amplifier units, therefore the number of amplifiers in the unit is equal to the number of the probing conductors in one row. An LED display panel 37 is attached to the end of the hollow shaft. LEDs 34, 36 are connected to the outputs of the electronic amplifier units 32, 33.

The work of the measuring unit is as follows. A bias voltage is applied to the probing electrodes 29, 38 through limiting resistors 16, 13, which is equal to a logical unity relative to the housing of the device 19 and the hollow shaft 17. Depending on the contact zone of the lip seal being investigated with the hollow shaft, the ends of the probing electrodes are in contact either with the lip seal material, or with conductive liquid. If the end of the probe electrode is in contact with a conductive liquid, then the voltage becomes equal to the logic zero level, since the bias voltage through the conductive liquid is closed to the body and the hollow shaft. The voltage from one group of probing electrodes is fed to the inputs of the corresponding block of electronic amplifiers and, after power amplification, is fed to the LEDs located in the LED display panel 37. On the LED display panel 37, only those LEDs are illuminated that are connected through the electronic amplifiers to the probing electrodes located in contact zone of the investigated lip seal with the shaft and therefore do not come into contact with an electrically conductive liquid. By the number of luminous LEDs in one group, it is possible to determine the instantaneous value of the contact width of the investigated lip seal 24 with the corresponding groove of the hollow shaft 17.

The LED display panel can be of various designs.

FIG. 3 shows a variant of the LED display panel for two groups of LEDs. FIG. 4 shows a variant of the LED display panel for four groups of LEDs. To indicate the axis of the shaft, a marker LED 35 is installed in the center of the display. The rest of the LEDs have an information function. The number of LED groups is equal to the number of slots in the hollow shaft. The number of LEDs in the group is equal to the number of probing conductors in the corresponding groove of the hollow shaft 17.

The receiving unit 12 serves to convert an optical signal into an electrical one, followed by selection and discrediting of this signal and its further transmission to the computer 10. The receiving unit includes: lens 4, CCD matrix 5, ADC 6 and control circuit 7. The receiving unit is controlled from a computer 10.

Electronic computer 10 operates according to a given program and performs the following functions: receiving and processing information received from the CCD - matrix 5, scanning control of the CCD - matrix 5, control of the rotational speed of the variable electric drive 11, output of measured data.

Preparing the device for operation is as follows. A hollow shaft 17 is placed in the body of the device 19, as well as locating rings 20, 22, 25, 28, auxiliary lip seals 21, 27 and the test seal 24. An electrically conductive liquid is poured into the cavity between the test seal 24 and the auxiliary seals 21, 27. The assembly of the entire device is carried out in such a way that the middle of the width of the contact zone of the lip seal under study with the hollow shaft 17 is located in the middle of the row of probing electrodes.

Thus, the considered device, in contrast to the known ones, makes it possible to increase the measurement accuracy by eliminating interference in the measurement information transmission circuits and allows one to measure the instantaneous value of the contact width of the lip seal with the shaft, as well as the displacement of the lip seal contact along the shaft simultaneously and locally at several points along the circumference of the shaft, form graphs of the dependences in time of the width of the contact and displacement of the lip seal at the given points of contact with the shaft.

Claims (1)

A device for testing a lip seal installed in a body cavity filled with an electrically conductive liquid, equipped with probing electrodes protruding to the contact surface of the sleeve with a hollow shaft, connected to a power source and limiting resistors, in which for simultaneous measurement of the value of the longitudinal displacement of the contact area along the shaft and the width of this contact depending on the angle of rotation of the shaft relative to the cuff, the probing electrodes are located in the shaft body, laid in series in a row and brought out to the surface of the shaft along a line approximately parallel to its axis, while the probing electrodes are connected to a power source and limiting resistors, characterized in that additionally contains a second auxiliary lip seal, and the probing electrodes are connected to the inputs of electronic amplifiers, the outputs of which are connected to an LED display fixed at the end of the hollow shaft to transmit the light flux to the receiving unit, while controlling The electric drive is carried out from an electronic computer using a digital-to-analog converter and a power amplifier.

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