Actuator with an electric motor

Abstract

The invention relates to an actuator (1) for automation technology designed to actuate a fitting, such as a valve, wherein the actuator has a force measuring device (70), which force measuring device is designed to measure a mechanical propelling force, causing the movement of an output, from a deflection of a resiliently mounted device from a resting position, wherein the electronic operating circuit is designed to derive a drive efficiency of the actuator from force measurement values relating to the output movement and from measured values of a mechanical motor force derived from motor current and / or motor voltage.

Description

[0001] Actuator with electric motor

[0002] The invention relates to an actuator in automation technology with an electric motor for operating a valve. Such actuators are also used in automation technology to operate valves such as armatures. For example, DE102019134805A1 shows an actuator in which a motor current is used to determine a motor temperature.

[0003] In the case of actuators with electric motors, the drive train of an actuator is subjected to considerable stress over time, so that wear and tear reduces the efficiency of the actuator.

[0004] The object of the invention is to propose an actuator in which the efficiency of the actuator can be measured.

[0005] The problem is solved by an actuator according to independent claim 1.

[0006] An actuator according to the invention in automation technology designed to operate a fitting such as a valve comprises:

[0007] A housing with a housing wall;

[0008] An electric motor;

[0009] An electronic operating circuit for operating the electric motor;

[0010] An output with an output axis or output shaft, which output is designed to actuate a valve by means of an axial movement or a rotary movement of the output axis or output shaft;

[0011] A transmission configured to transmit a force or a torque to the output, wherein the transmission comprises a plurality of toothed parts, such as gears or worms, which are mounted by toothed part bearings, such as transmission axes or transmission shafts; wherein the electric motor, transmission and electronic operating circuit are arranged in the housing, wherein the electric motor is configured to move the output linearly or rotationally by means of the transmission, wherein the actuator comprises a device which is spring-mounted in the housing by means of a spring device, which spring-mounted device is formed by the output or by a toothed part or by a toothed part bearing, wherein the actuator comprises a force-measuring device, which force-measuring device is configured toto measure a mechanical propulsion force causing the movement of the output from a deflection of the spring-mounted device from a rest position, wherein the electronic operating circuit is configured to derive a drive efficiency of the actuator from force measurement values ​​relating to the drive movement as well as from measured values ​​of a mechanical motor force derived from motor current and / or motor voltage. By comparing a propulsion force required for a movement of the output, which is independent of an efficiency of the actuator, and a motor force applied or generated by the electric motor, a conclusion can be drawn about a drive efficiency of the actuator. From the measured drive efficiency,Wear on the actuator can be detected, in particular, from a change in drive efficiency over time. If wear or a long-term change in efficiency is detected, the electronic operating circuit can, for example, be configured to issue a warning message. This allows a plant operator, for example, to replace an affected actuator if maintenance can be arranged without major inconvenience. This can prevent an expensive emergency shutdown or malfunction of the plant.

[0012] In one embodiment, the force measuring device is designed to convert a deflection of the spring-mounted device from the rest position against the spring device into a deflection-dependent measurement signal of an electronic measurement variable such as inductance, capacitance, current or voltage, wherein the force measuring device or the electronic operating circuit is designed to derive or calculate a measurement value for the propulsion force from the measurement signal.

[0013] In one embodiment, the force measuring device has a sensor for generating the measurement signal with, for example, a coil, a capacitor or a capacitor plate or a photodiode, wherein the force measuring device has a pickup which is designed to be moved by an axial or rotational movement of the spring-mounted device and thereby to bring about a change in the measurement signal of the electronic measurement variable.

[0014] In one embodiment, the force measuring device has a lever device with a lever bearing and with respect to the lever bearing a first end and an opposite second end, wherein the gripper forms the first end, wherein the second end is designed to influence a measured value of the electronic measurement variable in a position-dependent manner, wherein a lever length of the first end is in particular smaller than a lever length of the second end.

[0015] By using a smaller lever length at the first end, a small deflection of the spring-loaded device can be translated into a larger change in the measurement signal.

[0016] In one embodiment, the sensor has an end face, the second end being designed to at least partially cover the end face, a coverage proportion being dependent on the propulsive force against the spring device, the sensor having a coil, the second end being permanently magnetic or electrically conductive, the second end being designed to influence an inductance of the coil and the second end, or the sensor having a capacitor plate, the second end being electrically conductive, the second end being designed to influence a capacitance of the capacitor plate and the second end, or the sensor having a photodiode, the second end being designed to attenuate or block an incidence of light, for example from an LED.

[0017] In one embodiment, the second end is disc-shaped.

[0018] In one embodiment, measured values ​​of the measuring signal assume a value range with a maximum value and a minimum value, wherein a measured value of the measuring signal in the force-free state of the output assumes a value which is less than 30%, and in particular less than 25%, and preferably less than 20% of a difference between the maximum value and the minimum value away from a mean value of the value range.

[0019] In this way, a deflection of the spring-mounted device in both directions can be detected with sufficient detection margin.

[0020] In one embodiment, the spring device has at least a first spring element and at least one second spring element, wherein the at least one first spring element is designed to cause a force against a deflection of the output from the rest position in a first direction, wherein the at least one second spring element is designed to cause a force against a deflection of the output from the rest position in a second direction opposite to the first direction.

[0021] In one embodiment, the spring-mounted device is formed by the output, wherein a cross-sectional plane of the first spring element and a cross-sectional plane of the second spring element are at a distance of less than 30%, and in particular less than 25%, and preferably less than 20% of a diameter of the first spring element or the second spring element.

[0022] In this way, the spring-loaded mounting of the spring-loaded device can be made compact.

[0023] In one embodiment, the output axis is designed as a threaded spindle, wherein the threaded spindle is rotationally fixed, wherein the output has a spindle nut, wherein the electric motor is designed to drive the spindle nut rotationally by means of the gear and thereby to move the threaded spindle axially, wherein the output is spring-mounted in the housing in an axial direction of the threaded spindle by means of the spring device.

[0024] In one embodiment, the spindle nut is mounted radially by means of a rolling bearing, which rolling bearing is arranged at least partially in a cylindrical recess in the housing wall, wherein the cylindrical recess provides a stop for the rolling bearing against movement in the direction of a side of the cylindrical recess facing away from the housing, wherein the rolling bearing touches the stop when the output is in the rest position and / or is preloaded against the stop, wherein the at least one first spring element and the at least one second spring element act against the rolling bearing on a side of the rolling bearing facing the housing.

[0025] This contributes to a compact design of the actuator.

[0026] In one embodiment, the actuator has a spring plate fastened in the housing with a central opening through which opening the spindle nut is guided, wherein the spindle nut has a radial formation, in particular a collar, on a side of the spring plate facing away from the housing, which is designed to act directly or indirectly as a stop against the spring plate, wherein the spring plate is designed as one of the at least one first spring element.

[0027] This contributes to a compact design of the actuator.

[0028] In one embodiment, the spring plate is arranged outside the cylindrical recess, wherein the radial formation acts against the spring plate via the rolling bearing.

[0029] In one embodiment , the gear has a first toothed element such as a gear wheel which is rotatably connected to the spindle nut , wherein the spring device has at least one disc spring which surrounds the spindle nut and is designed as at least one of the at least one second spring element , wherein the at least one disc spring is arranged between the first

[0030] The toothing element and the rolling bearing are arranged and clamped. The invention is described below using exemplary embodiments.

[0031] Fig. 1 shows a cross section through an exemplary actuator according to the invention.

[0032] Fig. 2 shows an enlarged detail of the actuator shown in Fig. 1.

[0033] Fig. 3 shows a cross section through an exemplary actuator according to the invention.

[0034] Fig. 4 a) and b) sketch sensors of an actuator according to the invention.

[0035] Fig. 1 shows a cross-section through an exemplary actuator 1 according to the invention comprising a housing 10 with a housing wall 11, wherein an electric motor 20, an electronic operating circuit 30 for operating the electric motor, a gear 50, and an output 40 are arranged in the housing of the actuator. The output has an output axis 41 or output shaft 42, wherein the output is configured to actuate a valve by means of an axial movement or a rotational movement of the output axis or output shaft. The gear 50 is configured to transmit a force or a torque from the electric motor to the output and has toothed parts 51, such as gears 51.1 or worms 51.2, which are mounted on toothed part bearings 52, such as gear axes 52.1 or gear shafts 52.2. The electric motor is configured to move the output axially or rotationally.The actuator has a spring-mounted device 61 which is spring-mounted by means of a spring device 60. The spring-mounted device is formed, as shown here, by the output or alternatively by one of the toothed parts or by one of the toothed part bearings. According to the invention, the actuator has a force-measuring device 70 which is designed to measure a mechanical force causing the movement of the output from a deflection of the spring-mounted device from a rest position, wherein the electronic operating circuit is designed to derive a drive efficiency of the actuator from force measurement values ​​relating to the output movement and from measurement values ​​of a mechanical motor force derived from motor current and / or motor voltage.

[0036] By comparing the propulsion force required to move the output drive, which is independent of the efficiency of the actuator, and the force applied or generated by the electric motor, the drive efficiency of the actuator can be determined. Wear and tear on the actuator can be determined from the measured drive efficiency, and in particular from a change in the drive efficiency over time. If wear and tear or a long-term change in efficiency is detected, the electronic operating circuit can, for example, be set up to issue a warning message. In this way, a plant operator can, for example, replace an affected actuator if maintenance can be arranged without major inconvenience. This can prevent an expensive emergency shutdown or incorrect operation of the plant.

[0037] In one embodiment, the force measuring device 70 of an exemplary actuator according to the invention is configured to convert a deflection of the spring-mounted device 61 from the rest position against the spring device 60 into a deflection-dependent measurement signal of an electronic measurement variable such as inductance, capacitance, current or voltage, wherein the force measuring device or the electronic operating circuit 30 is configured to derive or calculate a measurement value for the force from the measurement signal.

[0038] Fig. 2 shows a section of the cross-section of the actuator 1 shown in Fig. 1. The output 40 of the actuator 1 can, as shown here, comprise a spindle-shaped output shaft 41 with a spindle nut 43. This spindle nut is driven via the transmission by means of a gear 51.1 to move the output shaft axially. The force measuring device can, as shown here, pick up the axial movement of the output shaft, for example via the spindle nut 43, via a lever device 72 with a pick-up arm 72.11.

[0039] The force measuring device as shown here by way of example has the lever device 72 with a lever bearing 72.01 and with respect to the lever bearing a first end 72.1 and a second end 72.2, in particular opposite, wherein the pick-up arm forms the first end, wherein the second end is configured to influence a measured value of the electronic measurement variable in a position-dependent manner, wherein a lever length of the first end is in particular smaller than a lever length of the second end.

[0040] A sensor 70.1 of the force-measuring device is configured to generate a measurement signal corresponding to the propulsion force. A sensor element 71 of the sensor may have an end face 71.1, with the second end 72.2 configured to at least partially cover the end face. The coverage portion depends on the propulsion force against the spring device and influences the measurement signal.

[0041] Measured values ​​of the measurement signal occupy a value range with a maximum value and a minimum value. In one embodiment, a measured value of the measurement signal in the force-free state of the output assumes a value that is less than 30%, and in particular less than 25%, and preferably less than 20% of a difference between the maximum value and the minimum value away from a mean value of the value range. In this way, a deflection of the spring-mounted device in both directions can be detected with sufficient detection margin.

[0042] The spring device 60 can, as shown here, have at least a first spring element 60. 1 and at least a second spring element 60. 2, wherein the at least one first spring element is designed to cause a force against a deflection of the output 40 from the rest position in a first direction, wherein the at least one second spring element is designed to cause a force against a deflection of the output from the rest position in a second direction opposite to the first direction.

[0043] The spindle nut 43 can, as shown here, be mounted radially by means of a rolling bearing 80, which rolling bearing is at least partially arranged in a cylindrical recess 11.1 in the housing wall, wherein the cylindrical recess provides a stop 11.11 for the rolling bearing against movement in the direction of a side of the cylindrical recess facing away from the housing, wherein the rolling bearing touches the stop and / or is preloaded against the stop when the output 40 is in the rest position, wherein the at least one first spring element 60.1 and the at least one second spring element 60.2 act against the rolling bearing on a side of the rolling bearing facing the housing, wherein the rolling bearing 80 is arranged in a cylindrical recess 11.1 in the housing wall 11. The cylindrical recess provides a stop 11.11 for the rolling bearing.A spring plate 90 fastened in the housing has a central opening 91 through which the spindle nut 43 is guided. The spindle nut has a radial formation 43.1, in particular a collar, on a side of the spring plate facing away from the housing, which is designed to act directly or indirectly as a stop against the spring plate. The spring plate is designed as one of the at least one first spring element 60.1. The spring plate 90 is arranged outside the cylindrical recess 11.1, with the radial formation 43.1 acting against the spring plate via the roller bearing 80. One of the toothed elements of the gear 50 is rotationally fixedly connected to the spindle nut 43. The spring device 60 has at least one disc spring, which engages around the spindle nut and serves as at least one of the at least one second spring element 60.2, wherein the at least one disc spring is arranged and clamped between the first toothed element and the rolling bearing. In this way, the spring device 60 can be implemented compactly.

[0044] Fig. 3 shows a cross-section through an exemplary actuator 1, which can be equipped with a force measuring device according to the invention. The electric motor 20 is configured to drive an output 40 with a gear 44 via a gearing 50 with a worm 51.2 as the toothed part 51. The worm is designed as a spring-mounted device 61, which is spring-mounted and clamped by a spring device 60 with a first spring element 60.1 and a second spring element 60.2 opposite the worm. The worm engages the gear 44 and is deflected against the spring device in accordance with the propulsive force imparted by the electric motor. According to the invention, a force measuring device can also be configured for this actuator, which detects the deflection of the worm against the spring device.

[0045] Sensor elements 71 are schematically sketched in Figs. 4 a) and 4 b). As shown in Fig. 4 a), the sensor element may comprise a coil 71.2, the second end being permanently magnetic and / or electrically conductive, the second end being configured to influence an inductance of the coil and the second end.

[0046] The sensor element can comprise a capacitor plate 71.3, as shown in Fig. 4 b), wherein the second end is electrically conductive, wherein the second end is configured to influence a capacitance of the capacitor plate and the second end. Alternatively, the sensor element can comprise a photodiode 71.4, wherein the second end is configured to attenuate or block incident light, for example, generated by an LED.

[0047] The invention is not limited to the embodiments shown in Figs. 1, 3 and 4; features of the embodiments can be interchanged if technically reasonable.

[0048] / List of reference symbols List of reference symbols

[0049] Actuator

[0050] Housing

[0051] Housing wall cylindrical recess stop

[0052] electric motor

[0053] Electronic operating circuit

[0054] downforce

[0055] Output axle

[0056] Output shaft

[0057] Spindle nut radial formation

[0058] gear

[0059] Gearbox

[0060] Gearing parts gear worm

[0061] Gearing part bearing Gear axis Gear shaft

[0062] Spring device first spring element second spring element spring-mounted device

[0063] Force measuring device sensor

[0064] Sensor element End face Coil Capacitor plate Photodiode

[0065] Lever device lever bearing first end gripper farm second end

[0066] Rolling bearings

[0067] Spring plate central opening

[0068] / Patent claims

Claims

Patent claims 1. Actuator (1) of automation technology designed to operate a fitting such as a valve comprising: A housing (10) with a housing wall (11); An electric motor (20); An electronic operating circuit (30) for operating the electric motor; An output (40) with an output shaft (41) or Output shaft (42), which output is designed to actuate a valve by means of an axial movement or a rotary movement of the output axis or output shaft; A transmission (50) configured to transmit a force or a torque from the electric motor to the output, wherein the transmission comprises a plurality of toothed parts (51) such as gears (51.1) or worms (51.2), which are connected by toothed part bearings (52) such as transmission axes (52.1) or gear shafts (52.2) are mounted; wherein the electric motor, gear and electronic operating circuit are arranged in the housing, wherein the electric motor is designed to move the output axially or rotationally by means of the gear, wherein the actuator has a device (61) which is spring-mounted in the housing by means of a spring device (60), which spring-mounted device is formed by the output or by one of the toothed parts or by one of the toothed part bearings, characterized in that the actuator has a force measuring device (70), which force measuring device is designed to measure a mechanical propulsion force causing the movement of the output from a deflection of the spring-mounted device from a rest position, wherein the electronic operating circuit is designed to derive a drive efficiency of the actuator from force measurement values ​​relating to the output movement and from measured values ​​of a mechanical motor force derived from motor current and / or motor voltage.

2. Actuator according to claim 1, wherein the force measuring device (70) is configured to convert a deflection of the spring-mounted device (61) from the rest position against the spring device (60) into a deflection-dependent measurement signal of an electronic measurement variable such as inductance, capacitance, current or voltage, wherein the force measuring device or the electronic operating circuit (30) is configured to derive or calculate a measurement value for the propulsive force from the measurement signal.

3. Actuator according to claim 2, wherein the force measuring device (70) comprises a sensor (70.1) for generating the measuring signal with, for example, a coil, a capacitor or a photodiode, wherein the force measuring device has a pick-off arm (72.11) which is designed to be moved by an axial or rotational movement of the spring-mounted device and thereby to cause a change in the measurement signal of the electronic measurement variable.

4. Actuator according to claim 3, wherein the force measuring device has a lever device (72) with a lever bearing (72.01) and with a first end (72.1) and a second end (72.2) which is in particular opposite the lever bearing, wherein the pick-up arm forms the first end, wherein the second end is designed to influence a measured value of the electronic measurement variable in a position-dependent manner, wherein a lever length of the first end is in particular smaller than a lever length of the second end.

5. Actuator according to claim 4, wherein the sensor (70.1) comprises a sensor element (71) with an end face (71.1), wherein the second end (72.2) is configured to at least partially cover the end face, wherein a coverage proportion is dependent on the propulsive force against the spring device, wherein the sensor element comprises a coil (71.2), wherein the second end is permanently magnetic and / or electrically conductive, wherein the second end is configured to influence an inductance of the coil and the second end, or wherein the sensor element comprises a capacitor plate (71.3), wherein the second end is electrically conductive, wherein the second end is configured to have a capacitance the capacitor plate and the second end, or wherein the sensor element comprises a photodiode (71.4), wherein the second end is configured to attenuate or block an incidence of light, for example by an LED.

6. Actuator according to claim 4 or 5, wherein the second end (72.2) is disc-shaped.

7. Actuator according to one of the preceding claims 2 to 6, wherein measured values ​​of the measuring signal occupy a value range with a maximum value and a minimum value, wherein a measured value of the measuring signal in the force-free state of the output takes a value which is less than 30%, and in particular less than 25%, and preferably less than 20% of a difference between maximum value and minimum value away from a mean value of the value range.

8. Actuator according to one of the preceding claims, wherein the spring device (60) has at least a first spring element (60.1) and at least one second spring element (60.2), wherein the at least one first spring element is designed to cause a force against a deflection of the output (40) from the rest position in a first direction, wherein the at least one second spring element is designed to cause a force against a deflection of the spring-mounted device (61) from the rest position in a second direction opposite to the first direction.

9. Actuator according to claim 8, wherein the at least one first spring element (60.1) and the at least one second spring element (60.2) encompass the output, wherein a cross-sectional plane of the first spring element and a cross-sectional plane of the second spring element are at a distance of less than 30%, and in particular less than 25%, and preferably less than 20% of a diameter of the first spring element or the second spring element.

10. Actuator according to claim 9, wherein the output axis (41) is designed as a threaded spindle, wherein the threaded spindle is rotationally fixed, wherein the output has a spindle nut (43), wherein the electric motor (20) is configured to drive the spindle nut rotationally by means of the gear and thereby to move the threaded spindle axially, wherein the output is spring-mounted in the housing in an axial direction of the threaded spindle by means of the spring device (60).

11. Actuator according to claim 10, wherein the spindle nut (43) is mounted radially by means of a rolling bearing (80), which rolling bearing is arranged at least partially in a cylindrical recess (11.1) of the housing wall, wherein the cylindrical recess has a stop (11.11) for the rolling bearing against a movement in the direction of a side of the cylindrical recess facing away from the housing, wherein the rolling bearing touches the stop and / or is preloaded against the stop when the output (40) is in the rest position, wherein the at least one first spring element (60.1) and the at least one second spring element (60.2) act against the rolling bearing on a side of the rolling bearing facing the housing.

12. Actuator according to claim 11, wherein the actuator has a spring plate (90) fastened in the housing with a central opening (91), through which opening the spindle nut (43) is guided, wherein the spindle nut has a radial formation (43.1) on a side of the spring plate facing away from the housing, in particular a collar, which is designed to act directly or indirectly as a stop against the spring plate, wherein the spring plate is designed as one of the at least one first spring element (60.1).

13. Actuator according to one of claims 11 or 12, wherein the spring plate (90) is arranged outside the cylindrical recess (11.1), wherein the radial formation (43.1) acts against the spring plate via the rolling bearing (80).

14. Actuator according to claim 12 or 13, wherein a first of the toothed elements of the gear (50) is rotationally fixedly connected to the spindle nut (43), wherein the spring device (60) comprises at least one disc spring, which at least one disc spring engages around the spindle nut and serves as at least one of the at least one second spring element (60.2), wherein the at least one disc spring is arranged between the first Gearing element and the rolling bearing are arranged and clamped. / Summary

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