DE102019214410A1 - Electromechanical safety brake - Google Patents

Abstract

An electromechanical safety brake is disclosed, the closing spring of which provides a contact force for a closed state of the safety brake, the contact force being many times higher than a restoring force which the closing spring has in an electrically operated open state of the safety brake.

Description

The invention relates to an electromechanical safety brake according to the preamble of claim 1.

Electromechanical safety brakes are actively released or released when an affected safety-relevant device is in operation with electrical current so that the device can be operated. If the control or the power supply fails, the safety brake is closed by a tensioned spring.

The invention is an improvement of the known safety brakes with regard to the continuous power consumption when such safety brakes are kept open.

Such a safety brake is disclosed from the prior art at the Internet address www.mayr.com/synchronisation/documentations/k_891_v17_de_26_03_2018.pdf. In the de-energized state, coil springs press against the armature disk. The rotor is held between the armature disk and the respective screw-on surface of the machine. The shaft is braked by the toothed hub. When the power is turned on, a magnetic field builds up. The armature disk is pulled against a coil carrier against the spring pressure. The rotor is free and the shaft can run freely. After switching off the power, in the event of a power failure or an emergency stop, the safety brake brakes reliably and safely.

Also the WO 2011/023728 A1 discloses such a spring pressure brake with coil springs which apply the necessary braking force in the closed state. A supplementary damping element is provided, the spring characteristic of which can be adjusted.

The disadvantage of these safety brakes is the high current required when the safety brake is open (released). In this state, the magnetic field of the coil works against the spring force of the coil spring (s). This magnetic field must be maintained continuously and must at least compensate for the force of the helical spring (s). The braking torque of the safety brake depends on the spring force in the closed / de-energized state. When the safety brake is opened, a strong magnetic field is required for a short time in order to achieve the force effect despite the large air gap and to attract the armature disk against the spring force. This strong magnetic field is actually no longer needed as soon as the armature plate is in contact with the coil side and there is no longer an air gap. In the safety brakes of the prior art, the strong magnetic field is maintained in this open state. This means that a strong current flows continuously, which represents a disadvantageous energy consumption, and heat is generated which is undesirable in the system.

From the available literature it can be seen that the required current could be reduced after the end position of the safety brake has been reached without the safety brake being applied unintentionally and unnoticed, e.g. due to vibrations. However, this reduced current also still leads to a considerable amount of heat being generated.

In contrast, the invention is based on the object of creating an electromechanical safety brake, the continuous power consumption of which is reduced in the open state.

This object is achieved by an electromechanical safety brake with the features of claim 1.

Further advantageous embodiments of the invention are described in the dependent claims.

The claimed electromechanical safety brake can be activated, ie closed, by a spring force of a spring arrangement. For this purpose, the spring arrangement has a relaxed closed position. The safety brake can be deactivated via an electromagnet, so the safety brake can be opened via the electromagnet. For this purpose, the spring arrangement has a tensioned opening position. According to the invention, a spring characteristic of the spring arrangement, which shows the spring force as a function of spring travel, has a falling working range between the closed position and the open position, whereby the spring arrangement has a higher spring force in its closed position than in its open position. After a certain initial force of the electromagnet, the necessary magnetic force in the open state of the safety brake is therefore reduced, whereby the power consumption in the open state of the safety brake is also reduced.

It is particularly preferred if the working range of the spring characteristic curve falls monotonically between the closed position and the open position. This means that the initially required magnetic force is no longer achieved and always decreases when the safety brake is opened. This means that the initially required current is no longer achieved and always decreases when the safety brake is opened.

If the opening position is close to a bistable position at a force zero point of the spring characteristic, the power consumption is in the open The state of the safety brake is minimal. The closer the opening position is to the zero point of force, the lower the power consumption.

In a preferred embodiment, the spring arrangement is formed by at least one plate spring.

The plate spring has a flat position in which the plate spring has a minimal thickness. This flatness is particularly preferred in the working range of the spring characteristic. In other words, the working area preferably extends on both sides of the flatness, so that the open position and the closed position of the plate spring are reached on different sides of the flatness.

In a specific embodiment of the safety brake according to the invention, a circumferential recess is formed on a coil carrier, into which the plate spring is inserted in at least sections. In a specific embodiment, the circumferential depression is frustoconical.

An inner edge or even an inner area of the plate spring is preferably received in the circumferential recess.

In the open position of the plate spring, an outer edge or even an outer area of the plate spring is preferably pressed into the circumferential recess.

In the closed position of the plate spring, an outer edge or even an outer area of the plate spring is preferably arranged outside the circumferential recess.

The spring arrangement or the disc spring can be formed as a conventional discrete component or, alternatively, integrally or in one piece on a larger component and thus as a functional sub-area of the component. This means that the component can be produced together with the spring arrangement in an additive process or in 3D printing.

In a specific embodiment, the component is the coil carrier.

The safety brake according to the invention is preferably used in a drive unit for robotics. Robotics can be mobile or stationary. In the latter case, the safety brake according to the invention can be arranged in a joint of a robot arm, for example.

An embodiment of the electromechanical safety brake according to the invention is shown in the figures.

• 1 in einem Längsschnitt die erfindungsgemäße elektromechanische Sicherheitsbremse gemäß dem Ausführungsbeispiel in einer geschlossenen Lage,
• 2 in einem Längsschnitt einen Teil der erfindungsgemäßen elektromechanischen Sicherheitsbremse in ihrer geöffneten Endlage und
• 3 eine Federkennlinie einer Tellerfeder aus den beiden vorhergehenden Figuren.

Show it

• 1 in a longitudinal section the electromechanical safety brake according to the invention according to the exemplary embodiment in a closed position,
• 2 in a longitudinal section part of the electromechanical safety brake according to the invention in its open end position and
• 3rd a spring characteristic of a disc spring from the two previous figures.

In the 1 The safety brake shown has a rotor 3rd on, which in the illustrated embodiment is rigid with a shaft to be released or braked 9 connected is. The spring arrangement is a non-linear disc spring 4th provided, over which the safety brake is tensioned in the closed position shown, in which the shaft 9 is fixed. Here is the disc spring 4th in their closed position 9 .

An electromagnet has a coil 1 and one with it (in 1 to the right) tightenable armature disk 2 and a bobbin 5 , which can also be part of a housing of the safety brake at the same time.

The design of the safety brake according to the invention relates in particular to the use of the plate spring 4th and the construction of their junctions. The scope of the changes according to the invention is in 1 and 2 shown in detail.

According to the exemplary embodiment of the invention, a helical spring with an approximately linear spring characteristic (spring force / spring deflection characteristic) is provided by the bistable disc spring 4th or snap disk with a non-linear spring characteristic 6th according to 3rd replaced. In 3rd is the work area 7th the disc spring 4th or their spring characteristic 6th arranged or shown between the two dashed lines.

In the braked (de-energized) state, the disc spring presses 4th with their maximum force against the armature disk 2 to build up the braking torque.

In order to open (release) the safety brake, the coil 1 a strong magnetic field built up for a short time. This creates the armature disk 2 against the spring force F acting on the coil carrier, which decreases over the spring travel s 5 drawn. A flat position 8th the disc spring 4th is exceeded.

The end position of the safety brake or the opening position 10 the disc spring 4th according to 2 is achieved when there is contact between coil 1 or bobbin 5 and armature disk 2 is reached. The disc spring 4th reaches when the safety brake is in its open position 10 almost the bistable position at the force zero point y.

In the applied end position of the safety brake or in the open position of the disc spring 4th the spring force F has been reduced to a small fraction of less than 10 percent of the force required for the braking torque. The magnetic field required to hold the safety brake in this end position can be reduced in the same way as the spring force F. This significantly reduces power consumption.

To the disc spring 4th in this open position 10 after reaching the end position of the safety brake, the magnetic field can be reduced very significantly due to the very low counterforce there and thus the continuously required current with the safety brake open can be reduced to a very small part of the current compared to the current at the beginning of the opening movement. This is particularly advantageous in mobile applications, since it extends the battery life and, in the case of highly integrated assemblies, can significantly reduce the development of heat.

The interaction between the armature disk 2 , the disc spring 4th and the bobbin 5 must be designed in such a way that deformation of the disc spring 4th about their flatness 8th addition is made possible by the disc spring 4th however, it is limited by reaching the force zero point y (cf. 3rd ) to prevent. To do this is the disc spring 4th in a circumferential recess 11 of the bobbin 5 used, which is frustoconical or conical in shape. The surrounding depression 11 is basically similar to the disc spring 4th in their open position 10 shaped.

In the in 2 shown opening position 10 is the disc spring 4th completely in this recess 11 recorded. In the in 1 shown closed position 11 is the disc spring 4th only with their inner area in this recess 11 recorded.

A differently shaped spring element which is essentially bistable or which is provided with a similar spring force curve can also be used. Several individual spring elements can also be used, all of which individually show such behavior, or at least generate such behavior in combination, e.g. a disc spring package.

An electromechanical safety brake is disclosed, the closing spring of which provides a contact force for a closed state of the safety brake, the contact force being many times higher than a restoring force which the closing spring has in an electrically operated open state of the safety brake.

QUOTES INCLUDED IN THE DESCRIPTION

This list of the documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent literature cited

• WO 2011/023728 A1 [0005]

Claims (11)

Electromechanical safety brake which can be activated via a spring force (F) of a spring arrangement, the spring arrangement having a closed position (9), and wherein the safety brake can be deactivated via an electromagnet, the spring arrangement having an open position (10), and the spring arrangement having a Has spring characteristic curve (6) which maps the spring force (F) as a function of a spring travel (s), characterized in that the spring characteristic curve (6) between the closed position (9) and the open position (10) has a falling working range (7), whereby the spring arrangement in its closed position (9) has a higher spring force (F) than in its open position (10). Electromechanical safety brake according to Claim 1 , the working range (7) of the spring characteristic (6) falling monotonically. Electromechanical safety brake according to one of the preceding claims, wherein the opening position (10) is close to a force zero point (y) of the spring characteristic (6). Electromechanical safety brake according to one of the preceding claims, wherein the spring arrangement is formed by at least one plate spring (4). Electromechanical safety brake according to Claim 4 wherein the plate spring (4) has a flat position (8) with minimal thickness, the flat position (8) being achieved in the working area (7) of the spring characteristic (6). Electromechanical safety brake according to Claim 4 or 5 , wherein a circumferential recess (11) is formed on a coil carrier (5), into which the plate spring (4) is inserted at least in sections. Electromechanical safety brake according to Claim 6 , wherein an inner edge of the plate spring (4) is received in the circumferential recess (11). Electromechanical safety brake according to Claim 6 or 7th , wherein in the open position (10) of the plate spring (4) an outer edge of the plate spring (4) is received in the circumferential recess (11). Electromechanical safety brake according to Claim 6 or 7th , wherein in the closed position (9) of the plate spring (4) an outer edge of the plate spring (4) is arranged in the circumferential recess (11). Electromechanical safety brake according to one of the preceding claims, wherein the spring arrangement is formed integrally or in one piece on a component of the safety brake. Electromechanical safety brake according to Claim 10 , wherein the component is a coil carrier (5).

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