Actuator indicator and actuator

Abstract

The invention relates to an actuator indicator (10) for an actuator (1) of automation technology comprising: an actuator indicator comprising a display gear (11) and a display unit (12), wherein the actuator indicator is configured by means of the display unit to indicate an actuation position of an output (20) of the actuator, wherein the actuator indicator is configured to be used in a potentially explosive atmosphere, wherein the actuator indicator has a display housing (13) with a non-impact-resistant viewing window (13.1) for checking the actuation position of the output, wherein the display gear has a power limiting device (11.1) which is configured to limit a mechanical power that can be transmitted to the display gear by mechanical friction in the display gear to a limit value.

Description

The invention relates to an actuator display and an actuator of automation technology.Actuating drives are used, inter alia, for process automation; an example is found in DE102004048366B4. Actuators often include actuator indicators that indicate an actuation position of the actuator.In explosive environments, actuator displays must meet increased requirements in order to be able to be used safely. For example, no dust must penetrate into an indicator gear because this would lead to a deterioration of the indicator gear, whereby critical temperatures could arise due to increased friction in the indicator gear upon actuation of the actuating drive, which critical temperatures could trigger, for example, an ignition of an ignitable gas.Usually, for this purpose, impact-resistant viewing windows according to the EN IEC 60079-0:2018 standard are used in order to ensure that the viewing window does not break. Such inspection windows are however heavy and expensive.It is therefore the object of the invention to propose an actuator display and an actuator in which requirements of the standard EN IEC 60079-0:2018 are complied with even without an impact-resistant viewing window.The object is achieved by an actuator display according to independent claim 1 and by an actuator according to independent claim 9.An actuator display according to the invention for an actuator of process automation technology comprises:an indicator gear having a plurality of toothed parts such as, for example, gearwheels or screws or nuts and associated supporting elements such as, for example, shafts or axles or spindles;and a display unit, wherein the actuator display is configured to display an operating position of an output of the actuator by means of the display unit,wherein the actuator indicator is configured to be used in an explosive environment,wherein the actuator display has a display housing with a non-impact-resistant viewing window for checking the actuation position of the output drive,wherein the display gear has a power limiting device which is designed to limit a mechanical power that can be transmitted to the display gear by mechanical friction in the display gear to a limit value.The impact strength is evident from the standard EN IEC 60079-0 of 2018.By limiting a mechanical power that can be converted in the display gear, it is possible to dispense with a shock-resistant viewing window of the actuating drive display. In the case of dust or dirt entering through a defective viewing window, the limitation of the power converted in the display transmission cannot reach a temperature which is sufficient for ignition in an ignitable environment. Deterioration of the efficiency of the indicator gear due to contamination can thus cause an only moderately elevated temperature during the actuation of the armature.In one configuration, the power limiting device is configured to limit a temperature increase caused by mechanical power in the display transmission.As a result, starting from a maximum ambient temperature in the region of the actuating drive, it can be ensured even in the event of a breakage of the viewing window that a temperature increase does not reach or exceed an ignition threshold of a gas mixture surrounding the actuating drive.In one embodiment, the temperature increase is limited to a maximum of 40 Kelvin or, in particular, a maximum of 35 Kelvin.As a result, in typical operating conditions of the actuator, a safe distance from an ignition temperature of the gas mixture surrounding the actuator can be maintained.In one configuration, the power limiting device has a torque limiting device such as a clutch. By matching a maximum torque with a maximum rotational speed at an input of the indicator transmission, the one upper limit of the transmittable power can be established.In one configuration, the power limiting device is configured to release a mechanical connection in the display transmission when the power limit value is reached and thus to interrupt a power flow.In one configuration, the display gear has a plurality of toothed parts such as, for example, gearwheels or screws or nuts and associated supporting elements such as, for example, shafts or axles or spindles, wherein a supporting element of the display gear has a predetermined breaking point which is configured to fail in the event of a limit torque, and / or wherein a supporting element of the display gear is formed in multiple parts, wherein two adjacent parts of the supporting element are rotationally fixed by means of a shear bolt, wherein the shear bolt is configured to fail in the event of a limit torque, and / or wherein a toothing of at least one toothed part of the display gear is configured to fail in the event of a limit torque.In one embodiment, the display gear is arranged in the display housing.In this way, a compact configuration of the actuator display can be achieved.In one configuration, the toothed parts and the supporting elements each have a heat capacity and a thermal conductivity, wherein a standard actuation of the output has an actuation duration and brings about an actuation rotational speed in the display transmission, wherein the toothed parts and the supporting elements are configured to limit the temperature rise by means of the heat capacity and thermal conductivity during a standard actuation in the case of a limit torque present in the display transmission as a result of the mechanical friction.By matching the heat capacity and thermal conductivity of the components present in the display transmission, a temperature rise which occurs under standard conditions when the limiting torque or the limiting power is present can be limited.For this purpose, the skilled person can use experiments or simulations or analytical calculations, for example.An actuator according to the invention comprises:an output for actuating a fitting, such as a valve;an electric motor configured to drive the output;an electronic operating circuit for operating the electric motor,an actuator transmission which is configured to transmit a force or a torque of the electric motor to the output and convert it,wherein the actuator has an actuator indicator according to the invention,wherein the actuator display is configured by means of the display gear to be coupled to the actuator gear or the output, wherein the display gear is configured to convert a movement of the actuator gear or the output into a positioning of a display element of the display unit,wherein the actuator is configured to be used in an explosive environment.In one embodiment, the actuator has an actuator housing with an actuator housing chamber, wherein the actuator transmission, the electric motor, the electronic operating circuit and the output are arranged in the housing chamber, wherein the display housing terminates flush with the actuator housing and in particular in a dust-proof manner.In this way, penetration of dust into the actuating drive and into the actuating drive indicator can be avoided.An assembly according to the invention comprises an actuator according to the invention and a fitting such as a valve, wherein the fitting is configured to be actuated by the actuator and to control a flow of medium through a pipeline or a conduit.The invention is described below with reference to exemplary embodiments. FIG. 1 outlines an actuator indicator; FIG. 2 shows a display gear; FIGS. 3 a), 3 b) and 3 c) show exemplary embodiments of a power limiting device of the display transmission according to the invention; FIG. 4 outlines an exemplary actuator according to the invention.FIG. 1 shows a schematic structure of an exemplary actuator display 10, which has a display housing 13 with a viewing window 13.1, a display unit and a display gear 11. The actuator display is configured to be mechanically connected to an actuator gear 50 or an output 20 of an actuator 1 of automation technology in order to translate movements of the actuator gear or the output into an actuation position of a fitting element or to represent this actuation position. This display is accomplished by means of a display unit 12. The display unit may be a mechanical or electronic display unit. As illustrated here, for example, display element 12.1 can display, such as a pointer to a value of a display scale 12.2, which display scale represents an actuation region of a fitting or of an output of the actuating drive.In the event of damage to the viewing window, dirt or dust, for example, can enter the display housing 13 from the environment and deposit on the display gear 11, which can result in a deterioration in efficiency of the display gear. During actuation of the armature by the actuating drive, such a deterioration in efficiency leads to a local increase in the temperature in the region of the indicator transmission.In order that such a display gear can also be used in explosive environments, it must be ensured according to the standard EN IEC 60079-0 of 2018 that under no realistic circumstances temperatures are produced which are sufficient for an ignition of a gas mixture surrounding the actuator display. In particular, the actuator satisfies one of the temperature classes T 1, T 2, T 3, T 4, T 5 or T 6 listed in the standard.In the prior art, the viewing window is typically made of a shock-resistant glass. Such glasses are heavy, bulky and also expensive.FIG. 2 outlines an exemplary schematic display gear 11 of the actuator display 10 comprising toothed parts 11.2 such as toothed wheels here (toothed arrangement is not shown here for illustrative reasons), which however can also be screws or spindle nuts, for example. The toothed parts are connected to supporting elements 11.3, such as shafts, axles or spindles, here shafts in a form-fitting, force-fitting or firmly bonded manner, which support the toothed parts.The display gear is configured to be connected to an actuator gear 50 or an output 20 of an actuator 1. The mechanical power, which drops when the valve is actuated by the actuating drive in the display transmission 11 at a given actuating drive power, increases with decreasing efficiency of the display drive. If, for example, the transmission is contaminated and more friction arises, the proportion of the mechanical power dropped across the display transmission becomes greater than the power provided by the actuating drive.This results in an increase in a temperature in the area of the display gear. With a sufficiently strong, but expensive and awkward viewing window, it can be ruled out that the viewing window breaks and dirt or dust penetrates into the transmission.FIGS. 3 a) to 3 c) show exemplary embodiments of the display gear according to the invention, in which a power limiting device and consequently a temperature rise limitation are set up, so that the setting up of a shock-proof viewing window 13.1 can be dispensed with, wherein the power limiting device 11.1 is set up to release a mechanical connection in the display gear when the power limit value is reached and thus to interrupt a power flow.In particular, the power limiting device is configured to limit a temperature increase arising in the display transmission to a maximum of 40 Kelvin or in particular a maximum of 35 Kelvin.According to the invention, the display transmission has a power limiting device 11.1, which can be designed as a torque limiting device. By limiting the power that can drop in the display gear, a temperature rise in the display gear caused by mechanical friction can be limited. For example, such a power limiting device as shown in FIG. 3 a) can be configured by tapering a supporting element of the display gear. This acts as a predetermined breaking point as soon as a torque limit value is exceeded. Since in actuating drives the electric motor is usually driven at a setpoint rotational speed, a power limit value is linked to the torque limit value.Alternatively, a power limiting device as outlined in FIG. 3 b) can also be formed by means of a shear bolt 11.4, which fixes two adjacent parts of a supporting element 11.32 against one another.Alternatively, the toothing of one of the toothing parts can also be configured to fail in the event of a limiting torque.Alternatively, as shown in FIG. 3 c), a clutch 11.12, such as a slip clutch 11.13, can also be configured in the display transmission, which is configured to release a frictional contact when a limit torque is reached, so that a power transmission is interrupted.The toothing parts 11.2 and the supporting elements 11.3 each have a heat capacity and a thermal conductivity. A standard actuation of the output 20 has a typical actuation duration and causes a typical actuation rotational speed in the display transmission in the display transmission. In one embodiment, the toothed parts and the supporting elements are configured to limit the temperature increase by means of the heat capacity and thermal conductivity when a limiting torque is present in the display transmission as a result of the mechanical friction during a standard actuation. The heat capacities of the toothing parts and of the supporting elements act as heat buffers, and the conductivities act as heat dissipation.In one embodiment, by adjusting the heat capacity and thermal conductivity of the components present in the display transmission, a temperature rise which occurs under standard conditions when the limit torque or the limit power is present is limited to a limit value.For this purpose, the skilled person can use experiments or simulations or analytical calculations, for example, in order to establish heat capacities and conductivities corresponding to the tooth parts and to the supporting elements.FIG. 4 outlines an exemplary actuator 1 with an actuator indicator 10 which terminates flush with an actuator housing 60 and in particular in a dust-proof manner. In this way, dust or dirt can be prevented from penetrating into an actuator housing chamber 61 of the actuator housing and into the display housing 13 of the actuator display 10. The display gear is mechanically coupled to the actuating drive gear 50, as outlined here, but can also be coupled to the output 20. By mechanically coupling to the actuator gear 50 or to the output 20, the actuator indicator may indicate an actuation position as well as changes thereto.The actuation position of the output drive, when combined in a corresponding assembly, correlates with an actuation position of a fitting element to be actuated by the actuating drive.List of reference characters1 Actuating drive 10 Actuating drive display 11 Display gear 11.1 Power limiting device 11.11 Torque limiting device 11.12 Clutch 11.13 Slipping clutch 11.2 Toothed part 11.3 Carrying elements 11.31 Predetermined breaking point 11.32 Parts of the carrying element 11.4 Shear pin 11.5 Input of the display gear 11.6 Output of the display gear 12 Display unit 12.1 Display element 12.2 Display scale 13 Display housing 13.1 Viewing window 20 Output 30 Electric motor 40 Electrical operating circuit 50 Actuating drive gear 60 Actuating drive housing 61 Actuating drive housing chamberReferences included in the specificationThis list of documents cited by the applicant has been produced in an automated manner and is only included for the better information of the reader. The list is not part of the German patent application or utility model application. The DPMA does not take any adhesion for any faults or omissions.Patent Literature citedDE 102004048366B4

[0002] Cited Non-Patent LiteratureStandard EN IEC 60079-0 of 2018

[0008]

Claims

Actuator display (10) for an actuator (1) in automation technology, comprising: a display gear (11) with several toothed parts (11.2), such as for example a gear wheel or worm or spindle nut, and associated support elements (11.3), such as for example shafts or axles or spindles; A display unit (12), wherein the actuator display is configured by means of the display unit to display an actuation position of an output (20) of the actuator, wherein the actuator display is configured to be used in an explosion-hazardous environment, characterized in that the actuator display has a display housing (13) with a viewing window (13.1) which is not impact-resistant according to the standard EN IEC 60079-0 of 2018 for checking the actuation position of the output, wherein the display transmission has a power limiting device (11.1) which is configured to limit a mechanical power which can be transmitted to the display transmission by mechanical friction in the display transmission to a power limit value.Actuator display according to claim 1, wherein the power limiting device (11.1) is configured to limit a temperature increase caused by mechanical power in the display gear (11).Actuator display according to claim 2, wherein the temperature increase is limited to a maximum of 40 Kelvin or in particular a maximum of 35 Kelvin.Actuator indicator according to one of the preceding claims, wherein the power limiting device (11.1) has a torque limiting device (11.11), such as a clutch (11.12).Actuator display according to one of the preceding claims, wherein the power limiting device (11.1) is configured to release a mechanical connection in the display transmission when the power limit value is reached and thus to interrupt a power flow.Actuator display according to one of the preceding claims, wherein a supporting element of the display gear has a predetermined breaking point (11.31) which is configured to fail in the event of a limit torque, and / or wherein a supporting element of the display gear is formed in multiple parts, wherein two adjacent parts (11.32) of the supporting element are rotationally fixed by means of a shear bolt, wherein the shear bolt (11.4) is configured to fail in the event of a limit torque, and / or wherein a toothing of at least one toothing part (11.2) of the display gear (11) is configured to fail in the event of a limit torque.Actuator display according to Claim 6, wherein the toothed parts (11.2) and the supporting elements (11.3) each have a heat capacity and a thermal conductivity, wherein a standard actuation of the output (20) has an actuation duration and brings about an actuation rotational speed in the display transmission, wherein the toothed parts and the supporting elements are configured to limit the temperature increase by means of the heat capacity and thermal conductivity to a limit value by means of the thermal capacity and thermal conductivity when a limit torque is present in the display transmission as a result of the mechanical friction during a standard actuation.Actuator display according to one of the preceding claims, wherein the display gear (11) is arranged in the display housing (13).Actuator (1) for automation technology, comprising: an output drive (20) for actuating a fitting, such as a valve, for example; an electric motor (30) which is configured to drive the output drive; an electronic operating circuit (40) for operating the electric motor, an actuator transmission (50) which is configured to transmit a force or a torque of the electric motor to the output drive and to convert it, characterized in that the actuator (1) has an actuator display (10) according to one of the preceding claims, wherein the actuator display is coupled to the actuator transmission (50) or the output drive (20) by means of the display transmission (11), wherein the display transmission is configured to convert a movement of the actuator transmission or of the output drive into a positioning of a display element of the display unit, wherein the actuator is configured to be used in an explosion-risk environment.Actuator according to Claim 9, wherein the actuator (1) has an actuator housing (60) with at least one actuator housing chamber (61), wherein the actuator transmission (50), the electric motor (30), the electronic operating circuit (40) and the output drive (20) are arranged in the housing chamber, wherein the display housing (13) terminates flush with the actuator housing (60) and in particular in a dust-tight manner.The actuator of claim 9 or 10, wherein the actuator indicator is modular.

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