CN106523710B

CN106523710B - Lip seal and method of determining the condition of a lip seal or a unit sealed thereby

Info

Publication number: CN106523710B
Application number: CN201610657510.5A
Authority: CN
Inventors: 安德烈亚斯·卡尔森
Original assignee: SKF AB
Current assignee: SKF AB
Priority date: 2015-08-11
Filing date: 2016-08-11
Publication date: 2021-05-25
Anticipated expiration: 2036-08-11
Also published as: CN106523710A; DE102016214942A1

Abstract

The invention provides a lip seal and a method of determining the condition of a lip seal or a unit to which it is sealed. Embodiments relate to a lip seal (100). The lip seal (100) comprises: a seal lip portion (105), a main body portion (115), and a magnet (110), wherein the magnet (110) is connected to one of the seal lip portion (105) and the main body portion (115). The other of the sealing lip portion (105) and the body portion (115) comprises a magnetic field sensor (120), the magnetic field sensor (120) being for detecting a distance between the magnet (100) and the magnetic field sensor (120) during operation of the lip seal (100).

Description

Lip seal and method of determining the condition of a lip seal or a unit sealed thereby

Technical Field

Embodiments relate to a lip seal and a method for determining the state of a lip seal or a unit sealed by a lip seal.

Background

Seals or sealing systems are widely used in many technical fields and come in many different forms. An example of an application for a common seal is a rotary application where a shaft rotates relative to a counterpart component (counter part) and attempts to protect components (e.g., mechanical or electrical components) from leakage, dust, or other potentially harmful substances. In such applications, the seal may be subjected to frictional forces that may result in an abrasive effect (abrasive effect), which may ultimately result in a failure of the seal. Conventional monitoring systems notify the user that a leak has occurred. However, this may require a backup for the failed seal, otherwise the user may risk causing other components to fail in use. Subsequently, the maintenance process may not be performed until damage has occurred. These problems may be further relevant in other applications where the seal is subjected to dynamic forces.

Disclosure of Invention

It is therefore desirable to provide an improved concept for monitoring the operational state of a seal.

According to a first aspect, embodiments relate to a lip seal. The lip seal includes a seal lip portion, a main body portion, and a magnet connected to one of the seal lip portion and the main body portion. The other of the sealing lip and the body portion includes a magnetic field sensor for detecting a distance between the magnet and the magnetic field sensor during operation of the lip seal. In other words, if the magnet is attached to the lip in one embodiment, the magnetic field sensor is then attached to the body portion. Vice versa, if the magnetic field sensor is attached to the lip in a different embodiment, the magnet is then attached to the body portion. It is thus possible to monitor the wear of the lip seal and even the operating state of the movable member providing the setting surface of the lip seal.

In some embodiments, the sealing lip mouth has an axis of symmetry, in other words, the sealing lip mouth is annular. The seal lip portion is capable of changing a distance between the magnet and the magnetic field sensor during operation by moving the seal lip portion relative to the main body portion in a radial direction perpendicular to the axis of symmetry. Furthermore, the rotational speed of the shaft may be measured.

In some embodiments, the lip seal further comprises a resilient element capable of partially blocking movement of the seal lip portion, the action of the seal lip portion being radially outward movement. In other words, the resilient element may exert a radially inward reaction force which is smaller than the force moving the sealing lip portion radially outward. The magnet is fixed to the elastic member. This may provide a way to increase the force used to seal the application and its components, thus making the lip seal more reliable.

In some embodiments, the elastic element has a first portion or branch (limb) in contact with the main body and a second portion or branch in contact with the sealing lip. The second part is moved in a radial direction relative to the first part. The magnet is mounted on the second portion and the magnetic field sensor is mounted on the first portion. Embodiments of the monitoring device using a lip seal of an elastic element can thus be simplified by pre-mounting the magnet and the magnetic field sensor on the elastic element before mounting the elastic element on the lip seal.

In certain embodiments, the resilient element is a hoop spring disposed in a circumferential direction and at least partially contains the annular space. The magnet is located within the annular space. This may result in better protection of the magnet from damage.

In some embodiments, the magnet is connected to a resilient element provided with a stem in the radial direction. The shaft may be a wedge (peg), a needle (pin) or a nail (stud). The end of the shaft facing the magnetic field sensor carries a magnet. This may provide an option to place the magnet closer to the sensor, which may result in a more accurate measurement.

In certain embodiments, the body portion is provided with a blind hole. The magnetic field sensor is attached to a closed end of a blind bore configured to at least partially receive an end of the bearing-mounted magnet. This way of embodiment where the magnet is mounted on the shaft may achieve a more stable.

In certain embodiments, the magnetic field sensor comprises a hall sensor. The magnetic field sensor may typically be an absolute magnetometer (absolute magnetometer) which measures the absolute strength of the magnetic field or a relative magnetometer (relative magnetometer) which measures the change in the magnetic field. Alternatively, the magnetic field sensor may comprise, for example, a magnetic field-dependent resistor (e.g., an XMR sensor), a superconducting quantum interference device (superconducting quantum interference device), an inductive pick-up coil (inductive pick-up coil), a vibrating sample magnetometer (vibrating sample magnetometer), or a Bose-Einstein glass-Einstein condensation magnetometer (Bose-Einstein condensation magnetometer). This may allow to provide a signal even if the magnetic field measured by the sensor is constant (in other words, the absolute strength of the measured magnetic field is constant).

In certain embodiments, the magnetic field sensor comprises an interface that provides a signal to the data storage device, the signal comprising information about a distance between the magnet and the magnetic field sensor. Thus, the time course of the wear of the lip seal or the time change of the operating state can be evaluated.

In certain embodiments, the magnetic field sensor comprises a transmitter module for providing a signal comprising information about the distance between the magnet and the magnetic field sensor. Thus, installation of the cable and complications with the cable can be avoided.

According to another aspect, embodiments relate to a method for determining the state of a unit or lip seal sealed by the lip seal. The condition or operating condition may include dynamic run-out (DRO), angular shaft eccentricity (angular draft misalignment), or shaft hole static eccentricity (STBM) of the shaft sealed by the lip seal. Furthermore, the rotational speed, the position of the shaft or wear can be determined and thus the life span of the lip seal estimated. The method includes measuring, by a magnetic field sensor of one of the body portion and the seal lip of the lip seal, a magnetic field originating from a magnet connected to the other of the body portion and the seal lip of the lip seal. This method of providing this may allow for continuous monitoring of wear or operating conditions.

Drawings

Certain embodiments of the apparatus and/or methods are described below by way of example only and with reference to the accompanying drawings in which:

FIG. 1a shows a lip seal according to an embodiment;

fig. 1b shows an arrangement of a magnet and a magnetic field sensor of a lip seal according to an embodiment;

fig. 2a to 2e show various measurements of different operating states of a unit or lip seal sealed by a lip seal using a magnet and a magnetic field sensor according to an embodiment; and

fig. 3a to 3d show various embodiments of a lip seal with a magnet and a magnetic field sensor.

Detailed Description

Various example embodiments will now be described more fully with reference to the accompanying drawings, in which some example embodiments have been shown. In the drawings, the thickness of lines, layers and/or regions are exaggerated for clarity.

Accordingly, while other embodiments of the invention are capable of various modifications and alternative forms, certain exemplary embodiments of the invention are shown by way of example in the drawings and will herein be described in detail. It should be understood that: it is not intended to limit the example embodiments to the particular forms disclosed, but on the contrary, the example embodiments are to cover all modifications, equivalents, and alternatives falling within the scope of the disclosure. The same reference numbers will be used throughout the description of the drawings to refer to the same or like elements.

It will be understood that when an element is referred to as being "connected to" another element, it can be directly connected or directly connected to the other element or intervening elements may be provided. In contrast, when an element is referred to as being "directly connected to" another element, there are no intervening elements present. Other words used to describe the relationship between elements should be interpreted in a similar manner (e.g., "in the middle of …" and "directly in the middle of …", "adjacent" and "directly adjacent", etc.).

The terminology used herein is for the purpose of describing particular example embodiments only and is not intended to be further limiting of example embodiments. As used herein, the singular is intended to include the plural unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and/or "comprising," when used herein, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which example embodiments belong. It will be further understood that: unless otherwise explicitly defined herein, terms (e.g., those defined in general dictionaries) should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art.

The first embodiment shown in fig. 1a relates to a lip seal 100. The lip seal 100 comprises a sealing lip portion 105, a magnet 110 connected to the sealing lip portion 105, and a body portion 115 comprising a magnetic field sensor 120, wherein the magnetic field sensor 120 is used to detect the distance between the magnet 110 and the magnetic field sensor 120 during operation of the lip seal. The lip seal may comprise a synthetic material such as a polymer (e.g., an elastomer). Body portion 115 may be attached to a locally fixed component. The lip 105 may be in dynamic or sliding contact with a movable component that provides a setting surface for the lip seal that forces the lip 105 to deform so that the lip 105 is urged towards the body portion 115. This then causes a restoring force (reset force) within the lip seal 100, thereby creating a sealing effect. The movable component may move along a linear path or may be a rotating component, such as a shaft. Furthermore, in other embodiments, the magnet 110 and the magnetic field sensor 120 may exchange their positions. The magnet 110 or sensor 120 may be adhesively bonded (e.g., glued) to the lip 105 or body portion 115, respectively. The magnet 110 may be attached to or embedded in the sealing lip portion 105. The magnetic field sensor 120 may be attached to or embedded in the body portion 115. Vice versa, the magnet 110 may be attached to or embedded in the body portion 115, or in another embodiment, the magnetic field sensor 120 may be attached to or embedded in the sealing lip portion 105.

In certain embodiments, the magnetic field sensor 120 comprises a hall sensor. This may allow measurements to be made where the magnetic field measured by the sensor is constant. The magnetic field sensor 120 may be selectively connected to a cable 125 or wire, which cable 125 or wire may provide a measurement signal to an electronic device (e.g., processor, display, data storage device, etc.). Optionally, the lip seal 100 may include a housing 130 partially embedded in the body portion 115. The housing 130 may be used for reinforcement or may be used to mount the lip seal 100 to a locally fixed assembly.

This may make it possible to monitor the wear of the lip seal 100 or the operating state of the movable components. Turning now to fig. 1b, the sealing lip 105 is shown in certain embodiments having an axis of symmetry 140, in other words, the lip seal 100 may seal media against the axis of rotational symmetry. The lip portion 105 may vary the distance 135 during operation by moving the lip portion 105 relative to the body portion 115 in a radial direction perpendicular to the axis of symmetry 140. Fig. 1b shows an arrangement of the magnet 110 and the magnetic field sensor 120 of the lip seal 100 according to an embodiment, wherein the lip seal 100 may seal the medium with respect to a rotating component (such as a shaft). The axis of symmetry 140 is perpendicular to the radial plane or image plane of fig. 1 b. The magnets 110 may be circular, for example, magnetic strips disposed along the outer circumference of the lip 105.

Thus, operating conditions such as dynamic run-out (DRO), angular shaft eccentricity (or shaft-to-body eccentricity, STBM) of the shaft sealed by the lip seal can be detected. Further, the rotational speed (e.g., Revolutions Per Minute (RPM)), the location of wear of the shaft or lip seal 100 may be measured (thus determining the estimated life span). These operating states will be explained in more detail below. The sensor 120 may measure the magnetic force of the magnet 110. This value is used to determine its distance 135 to the magnet 110 mounted in the sealing lip portion 105. The measurements may give information about DRO, RPM, STBM or lip wear. By the lip wear detection an indication of the remaining proportion of the lip 105 can be given.

Each of fig. 2a, 2b, 2c, 2d and 2e shows the measurement of the distance 135 over time for different operating states of the lip seal 100 or a unit sealed by the lip seal 100. Figure 2a shows that if a DRO occurs, a change in distance measurement over time may occur. DRO can be caused by shaft bending, vibration, jerking, and other errors. For example, a DRO may be described as the radial distance that a shaft cannot rotate around its true center. The effects that a DRO may have on the seal may include uneven wear and shorter seal life. The distance curve 210 may show a sinusoidal shape near the zero axis in the case of a DRO. The zero axis represents the ideal state (theoretically) where the DRO is 0, where the axis (shown by the solid circle on the right hand side of FIG. 2 a) is concentrically aligned with the hole (dashed circle) that receives it. In practical applications, slight DRO (e.g., up to 1%, 2%, or 5% of the shaft radius) may be unavoidable due to production tolerances of the unit including the shaft and the locally fixed assembly having the bore for receiving the shaft. The DRO may be proportional to and determined by the amplitude a of the measured distance curve 210. If the DRO exceeds a tolerance threshold, e.g., greater than 5% or 10% of the shaft radius, the magnetic field sensor may provide a signal with information about the change in distance over time and thus generate a warning signal. A warning signal may be provided to the user, for example by means of a monitoring connected to the magnetic field sensor.

Figure 2b shows the change in distance over time in the case where lip wear has occurred. Such as byAs explained above, in a practical application a slight DRO will be provided, and for better understanding the sinusoidally shaped distance curve is shown in an enlarged form in fig. 2 b. From the point of time t₀The first measurement started results in a sinusoidal first distance function 221(f (t) oscillating around the zero axis₀)). From the point of time t₁The initial second measurement results in a sinusoidal second distance function 222(f (t) that oscillates below the zero axis and about an axis parallel to the zero axis₁)). Compared with the time interval t₁-t₀The cycle time of the sinusoids here is negligible. Or, for example, the cycle time of the sinusoid may be at most one second or one minute, with a time interval t₁-t₀A minimum may be one hour or one day. In (f (t)₀) Are a and (f (t)₁) The offset w) may represent the amount of wear that has occurred during the time interval with respect to the lip.

Fig. 2c shows how the rotational speed of the shaft is measured. The rotation speed curve 230 exhibits the above-mentioned sinusoidal shape, the time (fr) of one full rotation can be obtained by measuring the time interval between two adjacent peaks of the sinusoidal function. The number of revolutions per minute is given by the time (fr) divided by 60. The rotational speed of a point on the surface of the shaft in meters per second can be obtained by the following equation:

where d is the diameter in millimeters as the unit axis.

In some embodiments, more than one magnetic field sensor may be attached to the lip seal. In one embodiment, four sensors S1, S2, S3, and S4 are installed at positions of 0 °, 90 °, 180 °, and 270 °, respectively. FIG. 2d shows the use of four sensors to measure DRO, wherein sensor S1 produces a first sinusoid 241, sensor S2 produces a second sinusoid 242, sensor S3 produces a third sinusoid 243, and sensor S4 produces a fourth sinusoid 244. Due to the position of the sensors, the curves of two adjacent sensors exhibit a phase difference of 90 ° between each other. The DRO causes the amplitude a of the curve to be equal and from this the DRO is determined.

Fig. 2e is similar to the case where STBM occurs. The deviation between the axis (shown as a solid circle at the lower left of fig. 2 e) and the hole (dashed circle) may be a static state caused by the offset of their centre lines. Evidence of this condition can be seen by the wider wear pattern on the lip on one side of the seal. FIG. 2e shows the measurement of STBM using four sensors as shown in FIG. 2d, wherein sensor S1 produces a first sinusoid 251, sensor S2 produces a second sinusoid 252, sensor S3 produces a third sinusoid 253, and sensor S4 produces a fourth sinusoid 254. In this embodiment, sensor S1 and sensor S3 are aligned on a vertical axis that is perpendicular to the axis of rotation, and sensor S2 and sensor S4 are aligned on a horizontal axis that is perpendicular to the axis of rotation and the longitudinal axis. Thus, the vertical deviation may be determined by the offset between the first sinusoid 251 and the third sinusoid 253, and the horizontal deviation may be determined by the offset between the second sinusoid 252 and the fourth sinusoid 254. The offset between the two curves can be calculated, for example, by using the difference between the minima of the respective curves.

Such embodiments may also be provided: the two lip seals are mounted at different axial locations of the shaft (e.g., on opposite sides of the bearing). This may be provided with an eccentric shaft of the shaft, wherein the axis of rotation of the shaft is inclined with respect to the bore. Similar to the STBM, skew shaft eccentricity also results in a wider wear pattern on the lip on one side of the seal.

Various embodiments of lip seals 100 that may be used are shown in fig. 3a, 3b, 3c and 3d, which are alternative embodiments to the embodiment shown in fig. 1 a. In fig. 3a to 3d, the assembly with the corresponding counterpart member in fig. 1a will not be explained again, only the differences between them being mentioned in the following. In some embodiments, the lip seal 100 further includes resilient members 305-1, 305-2 capable of partially blocking the action of the lip portion 105, the action of the lip portion 105 being radially outward movement. The magnet 110 is fixed to the elastic members 305-1, 305-2. This may provide a way to increase the force sealing against the application or its components, which may make the lip seal more reliable. In fig. 3a, 3b, 3c, the spring element 305-1 is a garter spring located in a circumferential groove, which is arranged on the surface of the sealing lip portion 105 facing radially outward.

In some embodiments, as shown in fig. 3a, the magnet 110 is connected to a resilient element 305-1 provided with a stem 315 radially. The end of the lever 315 facing the magnetic field sensor 120 carries the magnet 110. This brings the magnet 110 closer to the sensor 120, which can result in more accurate measurements. The handle 315 may be fixed to the elastic element 305-1, however, this is optional. In another embodiment, the stem 315 may be secured directly to the lip 105.

In certain embodiments, body portion 115 is provided with a blind bore 320. The magnetic field sensor 120 is attached to the closed end of a blind bore 320, the blind bore 320 being configured to be at least partially received in the end of the stem 315 carrying the magnet 110. This manner of embodiment in which magnet 110 is mounted on handle 315 may achieve greater stability. The magnetic field sensor 120 may, for example, be secured within a blind bore 320 having a cylindrical tube 325, the cylindrical tube 325 sandwiching the blind bore 320 and configured to at least partially receive the stem 315.

In some embodiments, as shown in fig. 3b and 3c, the elastic element 305-1 is a hoop spring disposed in a circumferential direction and at least partially comprises an annular space. In fig. 3b, the magnet 110 is located within the annular space. This may result in better protection of the magnet from damage. Fig. 3c shows an alternative embodiment, where the magnet 110 is mounted outside the annular space, but may be directly above the resilient element 305-1.

In some embodiments, the resilient element may take on a different shape than the cinch spring described above. As shown in fig. 3d, the resilient element 305-2 has a first portion 330 in contact with the body portion 115 and a second portion 335 in contact with the sealing lip portion 105. The second portion 335 moves radially relative to the first portion 330. The resilient element 305-2 may comprise, for example, a metallic material or a plastic. The magnet 110 is mounted on the second portion 335 and the magnetic field sensor 120 is mounted on the first portion 330. This may simplify the implementation of the monitoring device for a lip seal 100 using an elastic element, since the magnet 110 and the magnetic field sensor 120 may be mounted on the elastic element 305-2 in a previous step before assembly with the lip seal 100. As can be further seen in fig. 3d, the body portion 115 and the sealing lip portion 105 may be formed of different materials. For example, the seal lip portion 105 may be formed of an elastomer, and the main body portion may be formed of a metal material.

In certain embodiments, the magnetic field sensor comprises an interface that provides a signal to the data storage device, wherein the signal comprises information about the distance between the magnet and the magnetic field sensor. Thus, the wear course or the change in operating state over time on the lip seal can be assessed. The memory device may be embodied, for example, by a microprocessor that operates for a predetermined time and receives signals including sensor measurements. The microprocessor may then be connected to a computer, which may be used to evaluate the sensor measurements.

In certain embodiments, the magnetic field sensor comprises a transmitter module, wherein the transmitter module is configured to provide a signal comprising information about the distance between the magnet and the magnetic field sensor. Thus, installation of the cable and complications with the cable can be avoided.

According to another aspect, embodiments relate to a method for determining the state of a unit or lip seal sealed by the lip seal. The state or operating state may include dynamic eccentricity of the shaft sealed by the lip seal (DRO), skew shaft eccentricity, or shaft hole static eccentricity (STBM). Furthermore, the rotational speed, the position of the shaft or wear and thus the estimated life time of the lip seal can be determined. The method includes measuring, by a magnetic field sensor of a body portion of the lip seal, a magnetic field from a magnet coupled to a sealing lip portion of the lip seal to the sealing lip portion of the lip seal. This method of providing this may allow for continuous monitoring of wear or operating conditions.

Certain embodiments relate to a seal sensor for a radial shaft seal. In certain further embodiments, a hall sensor may be employed to measure the magnetic force of the magnet. This value can be used to know the distance to the magnet mounted on the main seal lip. This approach may provide information about dynamic eccentricity (DRO), RPM, shaft hole static eccentricity (STBM), and lip wear. By the lip wear detection, an indication of the remaining percentage of the lip 105 can be given.

Embodiments may provide information on the wear of the lip, as this may give an indication of how much of the seal lip remains before leaking. This information may give an indication to the customer when the seal must be replaced. In addition to lip wear, customers may also monitor operating conditions such as dynamic eccentricity (DRO), shaft hole static eccentricity (STBM), or RPM. Even if the seal has been erroneously installed (also referred to as a "skewed installation") with skew shaft eccentricity, the shaft bore static eccentricity can be detected.

In an embodiment, four hall effect sensors are mounted at 0 °, 90 °, 180 ° and 270 ° to measure the magnetic force from the magnet mounted on the seal main lip. The values from the sensors may be used to detect different operating states. In the case of dynamic eccentricity, the values may have a sinusoidal shape. The maximum and minimum values may determine the dynamic eccentricity of the shaft. Static eccentricity of the shaft bore can be detected using the difference between the sinusoidal peaks of the four sensors. Seal major lip wear may be measured at t₀And at a customized interval t₁t₂…t_nThe sinusoidal peak in time (e.g., only with the seal installed as a reference value) is monitored. The interval may include, for example, an hour, day, or month. The rpm may be measured by the frequency of the peak (minimum or maximum) of one of the sensors over a known period of time. Embodiments may provide a way for a user to monitor radial preload and wear of the seal lip mouth, as well as operating conditions (DRO, STBM, and RPM).

Certain further embodiments of the embodiments may be used, for example, in a slewing bearing (sliding bearing), a roller bearing, a ball bearing, a bushing or a sliding bearing. The magnet and sensor may measure the distance between the two bearing rings and the operating state of the bearing may be measured as described. The lip seal may for example be mounted on the outer bearing ring and the lip of the lip seal may be in sliding contact with the inner bearing ring.

The specification and drawings merely illustrate the principles of the disclosure. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the disclosure and are included within its spirit and scope. Moreover, all examples set forth herein are principally intended to be presented only for pedagogical purposes to aid the reader in understanding the principles of the disclosure and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting embodiments, aspects, and principles of the disclosure, as well as specific examples thereof, are intended to encompass equivalents thereof.

It will be appreciated by those skilled in the art that any block diagrams herein represent conceptual views of illustrative circuitry embodying the principles of the disclosure. Similarly, it will be appreciated that any flow charts, flow diagrams, state transition diagrams, pseudocode, and the like represent various processes which may be substantially represented in computer readable media and so executed by a computer or processor, whether or not such computer or processor is explicitly shown.

Furthermore, the claims are hereby incorporated into the detailed description, with each claim standing on its own as a separate example embodiment. While each claim is individually presented as a separate example embodiment, it will be noted that while the dependent claims in the claims refer to a particular combination of one or more claims, other example embodiments may also include combinations of dependent claims with the body portion of each other dependent claim or independent claim. Such combinations are presented herein unless the statement does not include a particular combination. Furthermore, it is intended to include features of a claim that are dependent on any other independent claim, even if that claim is not directly dependent on that independent claim.

It should also be noted that the methods disclosed in the specification or claims may be implemented by an apparatus having means for performing each of the individual acts in the methods.

Further, it should be understood that the disclosure of multiple acts or functions disclosed in the specification or claims are not to be interpreted in a particular order. Accordingly, the disclosure of multiple acts or functions does not limit the acts or functions to a particular order unless these acts or functions are not interchangeable for technical reasons. Further, in some embodiments, a single action may include or be broken down into multiple sub-actions. These sub-actions may be included and part of the disclosure of the single action unless explicitly excluded.

List of labels

100 lip seal

105 lip part

110 magnet

115 main body part

120 magnetic field sensor

125 cable

130 outer casing

Distance of 135

140 axis of symmetry

145 inner circumference

210 distance curve

221 first distance function

222 second distance function

230 curve of rotational speed

241 first sinusoid

242 second sinusoid

243 third sinusoid

244 fourth sinusoid

251 first sinusoid

252 second sinusoid

253 third sinusoid

254 fourth sinusoid

305-1, 305-2 spring element

310 recess

315 axle

320 blind hole

325 column pipe

330 first part

335 second part

Claims

1. A lip seal (100) comprising:

a seal lip portion (105) and a main body portion (115);

a magnet (110) connected to one of the seal lip portion (105) and the main body portion (115);

characterized in that the other of the sealing lip portion (105) and the main body portion (115) comprises a magnetic field sensor (120) for detecting a distance between the magnet (110) and the magnetic field sensor (120) during operation of the lip seal (100);

the lip seal (100) further comprises: an elastic element capable of partially blocking the action of the sealing lip portion (105), the action being radially outward movement, the magnet (110) being fixed on the elastic element;

the elastic element has a first portion (330) in contact with the main body portion (115) and a second portion (335) in contact with the sealing lip portion (105), wherein the second portion (335) is moved in a radial direction with respect to the first portion (330), wherein the magnet (110) is mounted on the second portion (335) and the magnetic field sensor (120) is mounted on the first portion (330).

2. A lip seal (100) comprising:

a seal lip portion (105) and a main body portion (115);

the magnet (110) is connected to an elastic element provided with a stem (315) in the radial direction, the end of the stem (315) facing the magnetic field sensor (120) carrying the magnet (110).

3. The lip seal (100) according to claim 1 or 2, wherein the sealing lip portion (105) has an axis of symmetry (140), the distance being variable during operation by a movement of the sealing lip portion (105) relative to the main body portion (115) in a radial direction perpendicular to the axis of symmetry (140).

4. The lip seal (100) of claim 2, wherein the body portion (115) is provided with a blind hole (320), wherein the magnetic field sensor (120) is attached to a closed end of the blind hole (320), wherein the blind hole (320) is configured to at least partially receive an end of the stem (315) carrying the magnet (110).

5. The lip seal (100) according to claim 1 or 2, wherein the magnetic field sensor (120) comprises a hall sensor.

6. The lip seal (100) according to claim 1 or 2, characterized in that the magnetic field sensor (120) comprises an interface providing a signal to a data storage device, the signal comprising information of the distance between the magnet (110) and the magnetic field sensor (120).

7. A method for determining the condition of a unit or lip seal sealed by the lip seal, the method comprising:

measuring a magnetic field originating from a magnet of one of the body portion and the seal lip portion of the lip seal by a magnetic field sensor of the other of the body portion and the seal lip portion of the lip seal according to any one of claims 1 to 6.