Method of reducing installation tolerances in the installation of a rotary encoder and installation kit for a rotary encoder

Abstract

Method of reducing installation tolerances in the installation of a rotary encoder in an elevator or escalator, installation kit for a rotary encoder of an elevator or escalator, and elevator or escalator. The method of reducing installation tolerances in the installation of a rotary encoder (2) to an electrical drive of an elevator or escalator, the rotary encoder (2) comprising: the position of the drive side connector (11) is centralized using a centralizing ring (20) that is placed on the drive side connector (11), after which the drive side connector (11) is fixed to shaft coupler (6) and the centralizing ring (20) is preferably removed; the rotary encoder (2) is centralized with regard to the shaft coupler (6) by positioning the rotary encoder (2) such that the rotor side connector (12) gets into contact with the drive side connector (11) -preferably such that the drive part connector (11) and rotor part connector (12) have such a shape that when they are pushed together, they are centralized to each other by the shape.

Description

[0001] METHOD OF REDUCING INSTALLATION TOLERANCES IN THE INSTALLATION OF A ROTARY ENCODER AND INSTALLATION KIT FOR A ROTARY ENCODER

[0002] The invention relates, on one hand, to improving the operation of rotary encoders for electrical drives, and, on the other hand, also to reducing installation tolerances between a rotary encoder and the shaft of a motor, in an elevator or escalator.

[0003] FIG 1 shows a rotary encoder 2 connected to an electrical drive 1. Rotatory encoders on electrical drives are used to precisely measure the angular position of the shaft with respect to the stator, which is required by the motor control system to correctly apply current to the windings and create a torque on the rotating shaft of the machine which is used to move and precisely position the car of an elevator or to control an escalator. FIG 1 also shows an auxiliary motor for an oil pump.

[0004] Rotary encoders 2 are sensitive high precision parts providing a signal of the angular position of the shaft in high resolution. The precise angular position between rotor and stator needs to be identified by electronic means of referencing the encoder after installation.

[0005] Available encoders use different physical principles (optical, magnetic, inductive, etc) to detect the speed / position of the machine’s rotor. Encoders can be realized as absolute encoders or incremental encoders. This invention, however, is independent of the encoder technology.

[0006] FIG 2 shows an example of a rotary encoder 2 that consists of a rotor part 5 which is connected to the shaft of the electrical drive machine via a shaft coupler 6 and a stationary part (housing 4, which is fixed to the non-rotating part of the electrical drive 1. The rotor part 5 preferably comprises a cone (or cut cone) shaped protrusion 3 which may be used for clamp ring mounting.

[0007] The rotary encoder 2 is not supposed to experience any significant radial or axial load, that is why runout and axial mounting tolerances are limited and restricted to small values provided in the datasheet of the encoder. In addition some encoder manufacturers provide elastic installation devices 7 (see FIG 2), which prevent damaging the encoder due to eccentricity. As an undesirable side effect, the elastic installation of the encoder housing can lead to a corrupt encoder signal, if a rotation of the housing is induced by error motion.

[0008] A corrupted encoder signal, not precisely representing the actual rotational movement of the shaft might lead to a false reaction from the inverter controlling the motor currents and finally impacts (ride quality of) the elevator system. A specifically critical case occurs, if the encoder generates an error signal at the frequency of rotation which coincides with a system Eigenfrequency leading to effects of resonance and thus an amplification of the oscillation amplitude.

[0009] For practical reasons and because of the big difference in size, the shaft of the encoder is mounted at the shaft end of the machine, in optimal case on the axis of rotation. Due to manufacturing and mounting tolerances, the geometry of the shaft of the electrical machine deviates from the ideal dimensions. The rigidly connected shaft of the encoder is forced to follow the movements of the shaft (translation and rotation), including all unwanted and parasitic small movements.

[0010] In addition to these effects, bearing play, elastic deformation of bearings and shaft, thermal effects and vibration of any origin lead to relative movements between the rotating parts of the encoder and the encoder housing, which might exceed the limits provided by the manufacturer.

[0011] This might lead to a corrupted encoder signal or mechanically damage the encoder. In both cases safe and smooth operation of the machine and the elevator car is in danger.

[0012] In the system of FIG 1, a motion amplification measurement was performed: Motion amplification measurement results show a harmonic motion with 60 pm amplitude of the drive shaft having a frequency corresponding to the speed of rotation of 3,5 Hz.

[0013] It is an objective of the invention to improve the operation of a rotatory encoder in an elevator or escalator that follows the rotary movement of the shaft of the electric drive via a shaft coupler.

[0014] This objective can be met with the installation kit for a rotary encoder according to claim 6, and with the elevator according to claim 8.

[0015] It is a second objective of the invention to reduce installation tolerances of a rotary encoder.

[0016] This objective can be met with the method according to parallel independent claim 1.

[0017] Dependent claims describe advantageous aspects of the method and of the installation kit.

[0018] According to the invention, to improve the operation of a rotatory encoder in an elevator or escalator, the rotatory encoder comprising i) a rotor part; ii) a stationary part, such as housing; the method in which: a) the stationary part is fixed to a non-rotating part of an electrical drive to provide as a stationary reference; b) the rotor part is connected to a coupling part of a rotor of an electrical drive of the elevator or escalator, using an elastic form-locking connector to transmit any rotational movement but allowing for radial and / or axial displacement of the rotor by elastic deformation of the elastic form-locking connector can be used to significantly mitigate radial or axial loads to the rotary encoder. In this manner, failures and errors resulting from the failure of the rotary encoder may be avoided. Furthermore, the operation time of a rotary encoder before its failure may be prolonged.

[0019] The elastic form-locking connector preferably comprises a rotor side connector which is fixed to the rotor part of the rotary encoder, advantageously in shape-locking or force-locking manner.

[0020] The elastic form-locking connector preferably comprises a drive side connector which is fixed to the coupling part of the rotor of the electrical drive, advantageously in shape-locking or forcelocking manner. Alternatively, it can be combined or integrated with it to save cost.

[0021] The elastic form-locking connector preferably further comprises a sleeve connecting the rotor side connector to the drive side connector such that the sleeve transmits rotational movement but allows for radial and / or axial displacement of the rotor by elastic deformation of the elastic form-locking connector.

[0022] The sleeve preferably shape-locks the drive side connector to the rotor side connector so that rotational movement may be transmitted by the sleeve in shape-locking manner between the rotor side connector and the drive side connector.

[0023] Thus, preferably, there is a gap between the drive side connector and the rotor side connector such that the drive side connector transmits rotatory movement to the rotor side connector solely via the sleeve.

[0024] In the method, a correct adjustment between the rotary encoder and the shaft of the electrical drive is preferably checked with the drive side connector touching the rotor side connector - preferably such that the drive side connector and rotor side connector have such a shape that when they are pushed together, they are centralized to each other by the shape- after which a gap is established after initially assembling the elastic form-locking connector and the rotary encoder. In the method according to first aspect of the invention, the rotary encoder and the elastic formlocking connector may be installed using the method according to the second aspect of the invention.

[0025] According to the second aspect of the invention, to reduce installation tolerances in the installation of a rotary encoder to an electrical drive of an elevator or escalator, preferably to attach a rotary encoder to an electrical drive of the elevator or escalator to be used after the installing in a method according to the first aspect of the invention, the rotary encoder comprising: i) a rotor part; ii) a stationary part, such as a housing; the following method is suggested: c) a drive side connector is connected to a shaft coupler of the elevator or escalator, preferably in a form-locking manner or in a force-locking manner; d) the position of the drive side connector is centralized using a centralizing ring that is placed on the drive side connector, after which the drive side connector is fixed to shaft coupler and the centralizing ring is removed; e) a rotor side connector is connected to the rotor part of a rotary encoder, preferably in a form-locking or force-locking manner; f) the rotary encoder is centralized with regard to the shaft coupler by positioning the rotary encoder such that the rotor side connector gets into contact with the drive side connector - preferably such that the drive part connector and rotor part connector have such a shape that when they are pushed together, they are centralized to each other by the shape; g) after centralizing the rotary encoder, changing the relative position of the rotor side connector to the drive side connector by moving one of these or both such that the rotor side connector is not in direct contact with the drive side connector such that a gap is formed; h) connecting the rotor part of the rotary encoder to follow a rotatory movement of the shaft coupler by attaching a sleeve to connect the drive side connector to rotor side connector such that the sleeve transmits rotational movement while dampening by its elastic deformation radial or axial loads.

[0026] The sleeve may comprise a bracket or a clamp which is suited to carry out the connecting in a shape-locking manner. Preferably, the sleeve is realized as a bellows coupling or comprises the same and preferably is made of steel.

[0027] The sleeve may be made of steel or substantially comprising steel. The drive side connector and rotor side connector may be made of brass or substantially comprising brass.

[0028] The Installation kit for a rotary encoder of an elevator or escalator comprises an elastic formlocking connector comprising a drive side connector, a rotor side connector -which drive side connector (11) and rotor side connector (12) are preferably of brass or substantially comprise brass- and a sleeve, -which sleeve (13) is preferably realized in the form of a bellows seal or comprising the same and preferably is made of steel, the installation kit preferably to be used in the method according to the invention.

[0029] The installation kit may further comprise a centralizing ring suited to centralize the drive side connector with regard to a shaft coupler, the centralizing ring preferably being disposed of after use.

[0030] The elevator or escalator comprises an electrical drive, a rotary encoder and the installation kit. The elastic form-locking connector has been installed to transmit rotational movement from a shaft coupler of the electrical drive to a rotor part of the rotary encoder via the sleeve such that there remains a gap between the drive side connector and rotor side connector, so that the sleeve transmits rotational movement while allowing for radial and / or axial displacement of the rotor by elastic deformation of the elastic form -locking connector (14), preferably the sleeve is realized as a bellows coupling or comprising the same and most preferably is made of steel.

[0031] FIG 1 shows an electrical drive connected to a rotary encoder;

[0032] FIG 2 shows an exemplary rotary encoder;

[0033] FIG 3 a currently used form-locking direct mounting of the rotary encoder on the shaft of the electrical drive;

[0034] FIG 4 mounting of the rotary encoder using the method according to second aspect of the invention with the installation kit;

[0035] FIG 5 illustrates the centralizing of the drive side connector with a centralizing ring; it is preferably removed after centralizing of the drive side connector.

[0036] FIG 6 illustrates the use of the method according to first aspect of the invention to transmit rotational movement of the shaft coupler to rotor part of the rotary encoder but allowing for radial and / or axial displacement of the rotor by elastic deformation of the elastic form-locking connector.

[0037] Same reference numerals refer to same parts in all FIG.

[0038] The rotatory encoder 2 comprises a rotor part 5 and a stationary part 4 (see FIG 1), such as housing. In the method for improving the operation of a rotatory encoder 2 following the operation of an electrical drive of an elevator or escalator, where the stationary part 4 is fixed to a non-rotating part of an electrical drive 1 to provide as a stationary reference. The rotor part 5 is connected to a coupling part 6 of a rotor of an electrical drive 1 of the elevator or escalator, using an elastic form -locking connector 14 to transmit any rotational movement but allowing for radial and / or axial displacement of the rotor by elastic deformation of the elastic form-locking connector 14 (see FIG 4).

[0039] The elastic form -locking connector 14 preferably comprises a rotor side connector 12 which is fixed to the rotor part 5 of the rotary encoder 2 preferably in shape-locking or force-locking manner.

[0040] The elastic form -locking connector 14 may further comprise a drive side connector 11 which is fixed to the coupling part 6 of the rotor of the electrical drive 1 preferably in shape-locking or force-locking manner. Alternatively, the elastic form -locking connector 14 may be combined or integrated with the rotor of the electrical drive.

[0041] The elastic form -locking connector 14 preferably further comprises a sleeve 13 connecting the rotor side connector 12 to the drive side connector 11 such that it transmits rotational movement but allows for radial and / or axial displacement of the rotor by elastic deformation of the elastic form -locking connector 14.

[0042] The sleeve 13 may shape-lock the drive side connector 11 to the rotor side connector 12 so that rotational movement is transmitted by the sleeve 13 in shape-locking manner between the rotor side connector 12 and the drive side connector 11.

[0043] There is preferably a gap d between the drive side connector 11 and the rotor side connector 12 such that the drive side connector 11 transmits rotatory movement to the rotor side connector 12 solely via the sleeve 13.

[0044] The cone (or cut cone) shaped protrusion 3 (see FIG 3) may be integrated in or combined with the rotor side connector 12, in order to save cost.

[0045] The correct adjustment between the rotary encoder 2 and the shaft of the electrical drive 1 may be checked with the drive side connector 11 touching the rotor side connector 12 -preferably such that the drive side connector (11) and rotor side connector (12) have such a shape that when they are pushed together, they are centralized to each other by the shape- after which a gap d is established (see FIG 4) after initially assembling the elastic form -locking connector 14 and the rotary encoder 2. So the centralizing surfaces are not touching each other in the work position of the elastic form -locking connector 14.

[0046] The rotary encoder 2 and the elastic form -locking connector 14 are preferably installed using the method described below.

[0047] In the method of reducing installation tolerances in the installation of a rotary encoder 2 to an electrical drive 1 of an elevator or escalator, preferably to attach a rotary encoder 2 to an electrical drive 1 of the elevator or escalator to be used after the installing in a method according to the first aspect of invention, c) a drive side connector 11 is connected to a shaft coupler 6 of the elevator or escalator, preferably in a form-locking manner or in a force-locking manner; d) the position of the drive side connector 11 is centralized using a centralizing ring 20 that is placed on the drive side connector 11, after which the drive side connector 11 is fixed to shaft coupler 6 (cf. FIG 5) and the centralizing ring 20 is preferably removed; e) a rotor side connector 12 is connected to the rotor part 5 of a rotary encoder 2, preferably in a form-locking or force-locking manner; f) the rotary encoder 2 is centralized with regard to the shaft coupler 6 by positioning the rotary encoder 2 such that the rotor side connector 12 gets into contact with the drive side connector 11 -preferably such that the drive part connector (11) and rotor part connector (12) have such a shape that when they are pushed together, they are centralized to each other by the shape; g) after centralizing the rotary encoder 2, changing the relative position of the rotor side connector 12 to the drive side connector 11 by moving one of these or both such that the rotor side connector 12 is not in direct contact with the drive side connector 11 such that a gap d is formed; h) connecting the rotor part 5 of the rotary encoder 2 to follow a rotatory movement of the shaft coupler 6 by attaching a sleeve 13 to connect the drive side connector 11 to rotor side connector 12 such that the sleeve 13 transmits rotational movement dampening by its elastic deformation radial or axial loads. The sleeve 13 preferably comprises a bracket or a clamp which is suited to carry out the connecting in a shape-locking manner.

[0048] The sleeve 13 may be realized as a bellows seal or comprising the same and preferably is made of steel.

[0049] Preferably, the sleeve 13 is made of steel or substantially comprises steel. The drive side connector 11 and rotor side connector 12 preferably are of brass or substantially comprise brass.

[0050] The installation kit for a rotary encoder 2 comprises elastic form -locking connector 14 comprising a drive side connector 11, a rotor side connector 12 and a sleeve, preferably to be used in the method according to the present invention.

[0051] The installation kit may further comprise a centralizing ring 20 suited to centralize the drive side connector 11 with regard to a shaft coupler 6 that preferably is disposed of after use.

[0052] As can be seen in FIG 6, the drive part connector 11 and rotor part connector 12 have preferably such a shape that when they are pushed together, they are centralized to each other by the shape.

[0053] The elevator or escalator comprises an electrical drive 1, a rotary encoder 2 and the installation kit, wherein the elastic form -locking connector 14 has been installed to transmit rotational movement from a shaft coupler 6 of the electrical drive 1 to a rotor part 5 of the rotary encoder 2 via the sleeve 13 such that there remains a gap d between the drive side connector 11 and rotor side connector 12, so that the sleeve 13 transmits rotational movement but allows for radial and / or axial displacement of the rotor by elastic deformation of the elastic form-locking connector 14.

[0054] In other words, an installation kit for a rotary encoder connection is suggested, which is based on an elastic coupling between the rotating shaft of the machine and the rotor of the encoder, allowing for some relative movements between the parts as well as runout and still provide precise transmission of the angular position of the rotor.

[0055] In addition to the elastic coupling, specifically designed mounting tools are used to precisely position and mount the non-rotating housing of the encoder with respect to the rotor to minimize initial errors increase the performance of the encoder.

[0056] Such an encoder installation allows to relax fabrication tolerances and installation precision to save cost without any disadvantage on function.

[0057] During tests, excessive movements of the encoder on the drive were detected, which disturb the position signal and finally the control loop, leading to heavy vibrations. To avoid the transmission of inevitable movements of the shaft to the encoder, the application of an elastic coupling between encoder and the rotating shaft of the machine is proposed.

[0058] As eccentricity of the encoder flange with respect to the shaft does not change under load, the process of precisely mounting the flange to the shaft can be addressed in the factory using suitable tools.

[0059] In measurements in a laboratory of the applicant it was found out that the stationary part of the rotary encoder is experiencing harmonic translatory movements with the rotating frequency of the electrical drive, which originates from the mounting tolerances and general movements of the shaft.

[0060] This is the reason for a corrupted encoder signal, which leads to a wrong commutation of the drive and to heavy vibrations.

[0061] In practice, in the situation shown in FIG 3, inaccuracies and all movements of the shaft are transmitted to the rotary encoder 2.

[0062] It is obvious to the skilled person that, along with the technical progress, the basic idea of the invention can be implemented in many ways. The invention and its embodiments are thus not limited to the examples described above but they may vary within the contents of patent claims and their legal equivalents.

Claims

Claims1. Method of reducing installation tolerances in the installation of a rotary encoder (2) to an electrical drive of an elevator or escalator, the rotary encoder (2) comprising: i) a rotor part (5); ii) a stationary part (4), such as a housing; and wherein in the method: a) a drive side connector (11) is connected to a shaft coupler (6) of the elevator or escalator, preferably in a form-locking manner or in a force-locking manner; b) the position of the drive side connector (11) is centralized using a centralizing ring (20) that is placed on the drive side connector (11), after which the drive side connector (11) is fixed to shaft coupler (6) and the centralizing ring (20) is preferably removed; c) a rotor side connector (12) is connected to the rotor part (5) of a rotary encoder (2), preferably in a form-locking or force-locking manner; d) the rotary encoder (2) is centralized with regard to the shaft coupler (6) by positioning the rotary encoder (2) such that the rotor side connector (12) gets into contact with the drive side connector (11) -preferably such that the drive part connector (11) and rotor part connector (12) have such a shape that when they are pushed together, they are centralized to each other by the shape; e) after centralizing the rotary encoder (2), changing the relative position of the rotor side connector (12) to the drive side connector (11) by moving one of these or both such that the rotor side connector (12) is not in direct contact with the drive side connector (11) such that a gap (d) is formed; f) connecting the rotor part (5) of the rotary encoder (2) to follow a rotatory movement of the shaft coupler (6) by attaching a sleeve (13) to connect the drive side connector (11) to rotor side connector (12) such that the sleeve (13) transmits rotational movement while dampening by its elastic deformation radial or axial loads.

2. The method of claim 2, wherein: the sleeve (13) comprises a bracket or a clamp which is suited to carry out the connecting in a shape-locking manner.

3. The method according to any one of the preceding claims, wherein: the sleeve (13) is realized as a bellows seal or comprising the same and preferably is made of steel.

4. The method according to any one of the preceding claims, wherein: the sleeve (13) is made ofsteel or substantially comprises steel, and wherein the drive side connector (11) and rotor side connector (12) preferably are of brass or substantially comprise brass.

5. Method of any one of the preceding claims 1 to 4, wherein: a correct adjustment between the rotary encoder (2) and the shaft of the electrical drive (1) is checked with the drive side connector (11) touching the rotor side connector (12) -preferably such that the drive side connector (11) and rotor side connector (12) have such a shape that when they are pushed together, they are centralized to each other by the shape- after which a gap (d) is established after initially assembling the elastic form -locking connector (14) and the rotary encoder (2).

6. Installation kit for a rotary encoder (2) of an elevator or escalator, comprising: elastic formlocking connector (14) comprising a drive side connector (11), a rotor side connector (12) - which drive side connector (11) and rotor side connector (12) are preferably of brass or substantially comprise brass, and a sleeve -which sleeve (13) is preferably realized in the form of a bellows seal or comprising the same and preferably is made of steel, the installation kit preferably to be used in a method according to any one of the preceding claims.

7. The installation kit of claim 6, further comprising: a centralizing ring (20) suited to centralize the drive side connector (11) with regard to a shaft coupler (6) that preferably is disposed of after use.

8. An elevator or escalator comprising: an electrical drive (1), a rotary encoder (2) and an installation kit according to claim 6 or 7, wherein the elastic form -locking connector (14) has been installed to transmit rotational movement from a shaft coupler (6) of the electrical drive (1) to a rotor part (5) of the rotary encoder (2) via the sleeve (13) such that there remains a gap (d) between the drive side connector (11) and rotor side connector (12), so that the sleeve (13) transmits rotational movement while dampening by its elastic deformation radial or axial loads, preferably the sleeve is realized as a as a bellows seal or comprising the same and most preferably is made of steel.

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