DE102019124150A1 - Mechanical position indicator and electric actuator - Google Patents

Abstract

Mechanical setting display, in particular for displaying a travel range of an electric actuator, with a drive shaft, a display element adjustable by means of the drive shaft, and a housing, the setting display having a threaded spindle for adjusting the display element and wherein the threaded spindle can be driven by the drive shaft via a slip clutch , in particular so that a relative position between the drive shaft and the threaded spindle is automatically adjustable as soon as the display element is in a first display end position

Description

Field of the invention

The invention relates to a mechanical positioning indicator, in particular for displaying a positioning path of an electric positioning drive, with a drive shaft and a display element that can be adjusted by means of the drive shaft.

The invention further relates to an electric actuator comprising an output shaft and a driven shaft aligned coaxially to the output shaft, as well as a sleeve which engages around opposite respective end sections of the output shaft and the driven shaft in a coupling area.

background

Mechanical position indicators and electric actuators are known in many ways. Among other things, however, such actuators and position indicators are used under extreme environmental conditions. For example, actuators and position indicators that are used in the oil industry must remain operational under extreme temperatures or as a result of extreme temperature fluctuations. Such environmental influences usually have a wear-promoting effect and affect, among other things, the positioning accuracy of actuators and the display accuracy of position indicators. However, incorrect operation may occur due to inaccuracies in the position indicator. For example, a position indicator that falsely indicates an “open position” of a valve in an oil pipeline can cause an operator to want to close the valve manually with a disproportionate application of force. The valve can be damaged as a result of excessive torques.

It is an object of the invention to improve the display accuracy of mechanical position displays. Furthermore, it is an object of the invention to provide an actuator with which the transmission of damaging torques to downstream components can be avoided.

Brief description of the invention

These objects are achieved by the aspects of the invention specified in the independent claims. Advantageous refinements can be found in the subclaims.

According to a first aspect of the invention, a mechanical setting display of the type mentioned is created, the setting display having a threaded spindle for adjusting the display element and the threaded spindle being drivable from the drive shaft by a slip clutch.

A movement of the display element, e.g. a pointer, can be decoupled from the movement of the drive shaft or a drive element by the slip clutch once a defined release force of the slip clutch is exceeded. The release force of the slip clutch can be adjustable. As a result, the slip clutch can also be adapted to different display elements. If the display element starts running against resistance, for example, the slip clutch can decouple it from a movement of the drive shaft. In this way, damage caused by too much force acting on the display element can be avoided. Furthermore, a position of the display element in relation to the drive shaft can be adjusted by the slip clutch. As a result, the display accuracy of the position indicator can be improved.

In particular, the slip clutch slips as soon as the display element reaches a first display end position. When the display element runs against a limitation in a first display end position, e.g. against a pointer support, a force (a torque) is exerted on the slip clutch. If this force exceeds a release force of the slip clutch, it slips through. As a result, a relative position between the drive shaft and the threaded spindle can be automatically adjusted as soon as the display element is in the first display end position. The approach of the display element against the boundary thus only leads to the release of the slip clutch and not to damage to the display element. The first display end position can indicate that a first end position of a travel of the actuator has been reached. The approach of the display element against the limitation therefore also leads to an automatic adjustment of the setting display to a changed end position. An automatic improvement in the display accuracy of the position indicator is thus achieved.

In one embodiment of the invention, the slip clutch also slips as soon as the display element reaches a second display end position which, together with the first display end position, defines a display area of the display element, the slip clutch being triggered in two drive directions with respect to the threaded spindle.

In addition to the first display end position, the display element can also run against a further limitation in a second display end position and thereby trigger the slip clutch. The second display end position can indicate that a second end position of a travel of the actuator has been reached. If the display element runs against the further limitation, i.e. a limitation in experiences opposite direction of movement in relation to a start against the first limitation in the first display end position, the triggering force acts in the opposite direction. The slip clutch can therefore be designed to release the relative movement between the display element and the drive shaft in both drive directions (directions of rotation of the drive shaft). This ensures that damage as a result of disproportionate expenditure of force in both directions of movement of the display element can be avoided. The approach of the display element against the limitation in the second display end position also leads to an automatic adjustment of the display to a changed second end position. A further automatic improvement in the display accuracy of the position indicator is thus achieved.

In one embodiment of the invention, the display element comprises a traveling nut which can be driven by the threaded spindle, so that a spindle drive is designed for linear adjustment of the display element, and wherein the threaded spindle blocks and thus triggers a slipping of the slip clutch as soon as the traveling nut and / or the display element a first end position is reached.

Both the display element and the traveling nut can run against a limitation and trigger the slip clutch. The traveling nut can encompass or carry the display element. An adjustment path of the actuator can be displayed on a linear scale with the display element. The linear scale can be arranged on a housing of the position indicator.

In one embodiment of the invention, the display element is arranged to be pivotable about a longitudinal axis of the threaded spindle, so that a swivel drive is designed for rotational adjustment of the display element, wherein the threaded spindle is connected to the display element in a rotationally fixed manner, or the threaded spindle drives the display element through a gear, whereby the threaded spindle blocks and thus triggers the slip clutch to slip as soon as the display element reaches the first end position.

The position indicator can be designed as a pivot indicator. An adjustment path of the actuator can be displayed on an angle scale with the display element. The angle scale can be arranged on a housing of the position indicator.

In one embodiment of the invention, the drive shaft drives the threaded spindle via a drive wheel when the slip clutch engages, in particular wherein the slip clutch is formed between the drive wheel and an end section of the threaded spindle.

The slipping clutch happens at a location with high torque. Because the drive wheel can have a relatively large diameter, the torque at the point of power transmission, i.e. where the slip clutch acts, is high. This enables "gentle" slipping. Snapping back, in particular the stick-slip effect, is avoided or at least mitigated. Therefore, the fatigue strength is further increased.

According to a second aspect of the invention, an electric actuator with a mechanical position indicator according to the first aspect of the invention is created, the actuator having an output shaft for adjusting an adjusting element, the output shaft being the drive shaft of the mechanical position indicator.

The actuator can be coupled to the mechanical position indicator and drive it. The output shaft can be driven by an electric motor of the actuator via a planetary gear.

According to a third aspect of the invention, an electric actuator of the type mentioned is created, wherein the output shaft and the driven shaft in the coupling area abut on axially aligned contact surfaces so that a drive torque can be transmitted from the output shaft to the driven shaft via the contact surfaces.

The drive torque transmitted via the contact surfaces can have a threshold value at which no or only a limited torque transmission is possible between the contact surfaces. As a result, a rotary movement of the driven shaft can be decoupled from a rotary movement of the output shaft. In this way, the transmission of damaging torques from the output shaft to the driven shaft (or vice versa) can be avoided.

In one embodiment of the third aspect of the invention, an inner diameter of the cuff is undersized in relation to a maximum outer diameter of the output shaft and the driven shaft, the cuff pressing the two contact surfaces against each other and / or a frictional connection between the cuff and the output shaft and between the sleeve and the driven shaft.

The sleeve can be used to establish the frictional connection between the two shafts. The undersize, or the interference fit between the sleeve and the shafts, can define a release force from which torque can no longer be transmitted between the shafts. The The cuff can therefore form a slip clutch. This can be produced simply and inexpensively.

In one embodiment of the third aspect of the invention, the contact surfaces are designed to be axially displaceable relative to one another.

This enables axial length compensation between the output shaft and the driven shaft. This can be particularly advantageous during production, namely if length compensation should be required before the sleeve is pulled onto the output shaft and the driven shaft.

In one embodiment of the third aspect of the invention, the contact surfaces are designed to be radially rotatable relative to one another, so that a tolerance-related inclined position of the output shaft and / or the driven shaft can be compensated for by means of the collar.

Damage to the coupling or the shafts due to tilting can thus be avoided.

In one embodiment of the third aspect of the invention, the cuff is arranged in the power flow between an output shaft of the actuator on the one hand and a position indicator and / or angle detection for the output shaft on the other.

The driven shaft can be a shaft of a position indicator. The sleeve can be used to form a slip clutch between an actuator and an indicator. It can thereby be achieved that no damaging torques can be transmitted from the actuator to the position indicator. This creates a safeguard through which damage to the position indicator can be avoided.

Figure list

• Die 1 eine beispielhafte Stellanzeige gemäß der Erfindung;
• Die 2 die Stellanzeige gemäß 1 in Draufsicht;
• Die 3 die Stellanzeige gemäß den 1 und 2 in einer Schnittdarstellung;
• Die 4 eine weitere beispielhafte Stellanzeige gemäß der Erfindung;
• Die 5 die weitere Stellanzeige gemäß 4 in einer Schnittdarstellung;
• Die 6 ein Funktionsschema der Stellanzeige gemäß den 1 bis 3;
• Die 7 ein Funktionsschema der Stellanzeige gemäß den 4 und 5;
• Die 8 eine schematische Darstellung eines elektrischen Stellantriebs gemäß der Erfindung;
• Die 9 eine schematische Darstellung des elektrischen Stellantriebs gemäß 8, der mit einer schematisch dargestellten erfindungsgemäßen Stellanzeige gekoppelt ist. Figurenbeschreibung

Exemplary embodiments of the invention are described in more detail below with reference to the accompanying drawings. It shows:

• The 1 an exemplary position indicator according to the invention;
• The 2 the position indicator according to 1 in plan view;
• The 3 the position indicator according to the 1 and 2 in a sectional view;
• The 4th a further exemplary position indicator according to the invention;
• The 5 the further position indicator according to 4th in a sectional view;
• The 6th a functional diagram of the position indicator according to the 1 to 3 ;
• The 7th a functional diagram of the position indicator according to the 4th and 5 ;
• The 8th a schematic representation of an electric actuator according to the invention;
• The 9 a schematic representation of the electric actuator according to 8th , which is coupled to a position indicator according to the invention shown schematically. Figure description

1 shows a vacancy 1 according to the invention. The position indicator comprises a housing 2 . On the case 2 is a transparent lid 3 put on. The transparent lid 3 forms an upper part of the housing 2 . A locking screw 4th fixes the transparent lid 3 on the housing 2 . The transparent cover allows a view of a display element 5 that are in an interior of the upper part of the housing 2 is arranged. The display element 5 is designed as a color-coded, barrel-shaped body of revolution. A lead screw 6th is central in the housing 2 arranged. An end section 7th the threaded spindle 6th protrudes from the housing. A drive wheel 8th is with the end section 7th the threaded spindle 6th connected. Between the drive wheel 8th and the case 2 is a slip clutch 9 arranged. The drive wheel is via a drive shaft 21 (not shown) driven. The slip clutch 9 includes a compression spring 10 . The compression spring 10 presses complementary coupling rings 11 between a surface of the drive wheel 8th and the case 2 against each other and creates a frictional connection between the drive wheel 8th and the lead screw 6th here.

2 shows the position indicator 1 according to 1 in plan view. The locking screw 4th is arranged in the center and holds the transparent cover on the housing 2 . The display element 5 is two-tone. In the case 2 is in relation to the display element 5 in the radial direction, but concentrically, a diaphragm 12th arranged. The aperture 12th has transparent and black, non-transparent sections. When the barrel-shaped colored sections of the display element are rotated 5 are through the non-transparent sections of the bezel 12th Parts of the colored areas of the display element 5 covered. The degree of obscuration is a measure of the degree of coverage by the display element 5 position to be displayed.

3 shows the position indicator 1 according to the 1 and 2 in a sectional view. The display element 5 is with the lead screw 6th non-rotatably connected and is moved over this. The display element 5 is formed by a barrel-shaped base body, which in relation to the aperture 12th is rotationally movable. Through the slip clutch 9 are the threaded spindle and the drive wheel 8th frictionally connected to each other. The compression spring 10 exerts a force on the clutch rings 11 and thus defines a release force or a critical torque from which the frictional engagement gives way and no more torque from the drive wheel 8th on the threaded spindle 6th can be transmitted and vice versa. If the indicator 5 against a limitation inside the housing 2 (not shown) starts up and is prevented from further movement by this, there is a torque between the threaded spindle and the driving drive wheel. The limitation can be a first display end position. If the torque exceeds the critical torque, the frictional connection gives way and the drive wheel 8th and threaded spindle 6th twist against each other until the torque falls below the critical torque again and the frictional connection is re-established.

4th shows a further exemplary embodiment of the position indicator 1 . In the case 2 , behind the transparent cover 3 , is the display element 5 . The position indicator 1 comprises an annular, colored display body 13th . The display element 5 is along the lead screw 6th axially movable. The axial position of the display element 5 in terms of the housing 2 is the measure of one through the display element 5 position to be displayed.

5 shows the position indicator 1 according to 4th in a sectional view. The display element 5 is in one piece with a traveling nut (spindle nut) 14th educated. The traveling nut 14th is along the lead screw 6th axially movable. A guide pin 15th runs parallel to the threaded spindle 6th and prevents the display element from rotating 5 . The display element 5 located in relation to the housing 2 in a lowest position and signals a "closed position". If the indicator 5 or the traveling nut 14th along the threaded spindle 6th are moved to an outermost upper position, an "open position" is signaled. It is possible that the display element 5 or the traveling nut 14th against the display body 13th or an upper limit (not shown), which in particular defines a first display end position, and a torque is applied to the threaded spindle 6th produce. Will be a critical torque like too 3 Reached as described, the slip clutch releases 9 and allows a rotation between the drive wheel 8th and threaded spindle 6th . Likewise, if the display element 5 in the "closed position" shown against a lower limit (for example the housing 2 ) starts, which defines a second display end position, in the same way a torque on the threaded spindle 6th be generated. If the critical torque is exceeded, this torque causes the slip clutch to slip, as described above 9 , but in the opposite direction of rotation.

6th shows a functional diagram of the position indicator 1 according to the 1 to 3 . The display element 5 is inside the case 2 pivotable. Its rotation around the longitudinal axis of the threaded spindle 6th forms the dimension for a setting position to be displayed. Its display area is therefore determined and limited by a rotation option. Therefore, the boundaries can be designed as stops, which upon contact with the display element 5 the slip clutch 9 trigger as described.

7th shows a functional diagram of the position indicator 1 according to the 4th and 5 . The display element 5 is inside the case 2 axially movable. Its displacement along the longitudinal axis of the threaded spindle 6th forms the dimension for a setting position to be displayed. Its display range is therefore determined and limited by an axial position. Therefore, the boundaries can be designed as stops, which upon contact with the display element 5 the slip clutch 9 trigger as described.

8th shows an electric actuator 16 according to a further aspect of the invention. The actuator 16 has an output shaft 17th and a driven shaft 18th on. The driven shaft 18th is through the output shaft 17th driven. The actuator 16 has a cuff 19th on. The cuff 19th engages around end sections of the output shaft 17th and the driven shaft 18th . The output shaft 17th and the driven shaft 18th have mutually complementary contact surfaces 20th on. The contact areas 20th can be axially aligned with one another. The contact areas 20th are from the cuff 19th enclosed and protected against external influences. A torque to drive the driven shaft 18th through the output shaft 17th is over the contact surfaces 20th from the output shaft 17th on the driven shaft 18th transfer. The cuff 19th is by means of an interference fit with both the output shaft 17th as well as with the driven shaft 18th connected. The cuff 19th presses the contact surfaces against each other and contributes to the frictional connection. Alternatively, there is frictional engagement only between the cuff 19th and the driven shaft 18th or the output shaft 17th .

9 shows a schematic representation of the electric actuator 16 according to 8th , the one with a position indicator according to the invention 1 is coupled. An output shaft 17th for adjusting the adjusting element 5 (not shown) the position indicator 1 is also the drive shaft of the position indicator 21 . The drive shaft of the position indicator 21 can with the driven shaft 18th how to 8th be identical.

List of reference symbols

1

Position indicator

2

casing

3

Transparent lid

4th

Screw

5

Display element

6th

Threaded spindle

7th

End section of the threaded spindle

8th

drive wheel

9

Slip clutch

10

Compression spring

11

Coupling rings

12th

cover

13th

Annular display body

14th

Running nut

15th

Guide pin

16

Actuator

17th

Output shaft

18th

Driven shaft

19th

cuff

20th

Contact surfaces

21

Drive shaft of the position indicator

Claims (12)

Mechanical position indicator (1), in particular for displaying a travel range of an electric actuator (16), with a drive shaft (21); a display element (5) adjustable by means of the drive shaft (21); characterized in that the position indicator (1) has a threaded spindle (6) for adjusting the display element (5); and the threaded spindle (5) can be driven from the drive shaft (21) by a slip clutch (9). Mechanical position indicator (1) according to Claim 1 , the slip clutch (9) slipping as soon as the display element (5) reaches a first display end position. Mechanical position indicator (1) according to Claim 2 , the slip clutch (9) also slipping as soon as the display element (5) reaches a second display end position which, together with the first display end position, defines a display area of the display element (5), the slip clutch (9) related in two drive directions can be triggered on the threaded spindle (6). Mechanical position indicator (1) according to one of the preceding claims, wherein: the display element (5) comprises a traveling nut (14) which can be driven by the threaded spindle (6) so that a spindle drive is designed for linear adjustment of the display element (5); and the threaded spindle (6) blocks and thus triggers the slip clutch (9) to slip as soon as the traveling nut (14) and / or the display element (5) reaches a first end position. Mechanical position indicator (1) according to one of the preceding claims, wherein: the display element (5) is arranged to be pivotable about a longitudinal axis of the threaded spindle (6), so that a pivot drive is formed for the rotational adjustment of the display element (5); the threaded spindle (6) is non-rotatably connected to the display element (5); or wherein the threaded spindle (6) drives the display element (5) through a gearbox; the threaded spindle (6) blocks and thus causes the slip clutch (9) to slip as soon as the display element (5) reaches the first end position. Mechanical position indicator (1) according to one of the preceding claims, wherein the drive shaft (21) drives the threaded spindle (6) via a drive wheel (8) when the slip clutch (9) engages, in particular with the slip clutch (9) between the drive wheel (8 ) and an end section (7) of the threaded spindle (7) is formed. Electric actuator (16) with a mechanical setting indicator (1) according to one of the preceding claims, characterized in that the actuator (16) has an output shaft (17) for adjusting an actuator (5); wherein the output shaft (17) is the drive shaft (21) of the mechanical position indicator (1). Electric actuator (16), in particular for a mechanical position indicator according to one of the preceding claims, comprising: an output shaft (17) and a driven shaft (18) aligned coaxially with the output shaft (17); as well as a sleeve (19) which engages around opposite respective end sections of the output shaft (17) and the driven shaft (18) in a coupling area; characterized in that the output shaft (17) and the driven shaft (18) bear against one another in the coupling area at axially aligned contact surfaces (20); so that a drive torque can be transmitted from the output shaft (17) to the driven shaft (18) via the contact surfaces (20). Actuator (16) according to Claim 8 , an inner diameter of the sleeve (19) being undersized in relation to a maximum outer diameter of the output shaft (17) and the driven shaft (18), the sleeve (19) pressing the two contact surfaces (20) against one another and / or a frictional connection exists between the collar (19) and the output shaft (17) and between the collar (19) and the driven shaft (18). Actuator (16) according to Claim 8 or 9 , the contact surfaces (20) being axially displaceable relative to one another. Actuator (16) according to one of the Claims 8 to 10 , wherein the contact surfaces (20) can be rotated radially with respect to one another, so that a tolerance-related inclination of the output shaft (17) and / or the driven shaft (18) can be compensated for by means of the sleeve (19). Actuator (16) according to one of the Claims 8 - 11 , wherein the sleeve is arranged in the power flow between the output shaft (17) of the actuator (16) on the one hand and a position indicator (1) and / or an angle detection for the output shaft (17) on the other hand.

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