Laboratory mill, in particular rotor or centrifugal mill

Abstract

The invention relates to a laboratory mill (1) for grinding material, in particular a rotor or centrifugal mill, comprising: a device housing (30) with a housing cover (36) with which a grinding chamber (98) inside the device housing (30) can be sealed off from the environment, an electric drive motor (102), a grinding assembly (74) that can be inserted into the grinding chamber (98), which a shredding rotor (52) which can be rotated by the drive motor (102), a stationary ring-shaped counter element (54) that can be arranged around the shredding rotor (52), a sample collection container (56) and a collection container lid (72) with which the sample collection container (56) inside the grinding chamber (98) can be closed, wherein the grinding assembly (74) defines a central rotor chamber (62) arranged radially inside the stationary annular counter element (54) and a peripheral annular sample collection chamber (64) arranged radially outside the stationary annular counter element (54), a collection container lid sensor device (212) which detects the presence and / or correct seating of the collection container lid (72) on the sample collection container (56) in the grinding chamber (98).

Description

Field of invention

[0001] The invention relates to a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which effectively grinds the material by impact, blow, and / or shear action using a rotating grinding rotor, which is surrounded in an annular sample collection container by a stationary annular counter element, e.g. in the form of an annular sieve, an annular impact bar or an annular counter blade insert. Background and general description of the invention

[0002] Rotor mills, sometimes also called rotor high-speed mills or centrifugal mills, typically operate with a grinding rotor rotating around a vertical axis, surrounded by a stationary, ring-shaped counter element. The shape and design of the rotor can vary depending on the application. The ring-shaped counter element can be, for example, a ring screen, a so-called impact bar, or a ring-shaped counter-blade insert. The shape and size of the screen perforations can be selected according to requirements. The impact or cutting geometry of the rotor is typically located in the radially outer region of the rotor diameter. In a commonly used grinding assembly with an impact rotor and ring screen, the rotor typically consists of a horizontal circular base plate with a plurality of vertical impact teeth extending around its peripheral edge, parallel to the axis of rotation. These impact teeth thus form, for example...A ring-shaped colonnade, coaxial to the axis of rotation, is located in the radial outer area of ​​the rotor. Comminution occurs, for example, through impact, blow, and / or shear action by the impact teeth in the peripheral ring-shaped outer region of the rotor when it rotates at high speed around the vertical axis of rotation. The rotor's impact teeth thus collectively form a coaxial cylindrical shell within which the material to be ground is comminuted. This cylindrical shell of the impact teeth is directly surrounded by the cylindrical ring screen with a relatively small annular gap between them, so that the material to be ground is comminuted directly against the cylindrical inner surface of the ring screen and / or between the impact teeth and the ring screen. Once the material has reached a sufficient fineness, it can exit radially outwards through the perforations of the ring screen.The rotor and the ring sieve are arranged in a collection container, which forms a collection chamber surrounding the ring sieve in a ring shape, in which the crushed material exiting radially outwards through the sieve perforation is collected.

[0003] The collection container is typically sealed with a separate inner lid or collection container lid. The assembly of the collection container and inner lid, possibly together with the ring sieve and / or the rotor, forms an interchangeable grinding unit that can be inserted into the instrument housing and is sometimes also referred to as a cassette or interchangeable cassette. The rotor is mounted axially on the shaft of an electric drive motor. Typically, the drive motor for the rotor is installed vertically in the laboratory mill. This allows the user to feed the sample from above through a hopper and place it directly onto the rotating rotor. The short feed path reduces sample carryover. Furthermore, it keeps the number of components to a minimum and facilitates cleaning after grinding.The grinding unit is inserted into an upper section of the device housing, which is then closed for the grinding process with a housing cover, such as a hinged hood. For user safety reasons, the grinding process can only be started when the hood is locked.

[0004] Such rotor mills are described, for example, in DE 100 22 849 A1, DE 100 66 027 A1, DE 10 2012 010 065 A1, DE 20 2012 013 666 U1 and DE 20 2012 013 667 U1, which are hereby incorporated by reference.

[0005] Examples of rotor (high-speed) mills are the Pulverisette® 14 classic line and the Pulverisette® 14 premium line of the applicant, which are presented on its website www.fritsch.de, cf. www.fritsch.de / probenaufbereitung / mahlen / rotor-schlagmuehlen / details / produkt / pulverisette-14-classic-line / and www.fritsch.de / probenaufbereitung / mahlen / rotorschlagmuehlen / details / produkt / pulverisette-14-premium-line / . The descriptions, brochures, instructions, etc. contained on or downloadable from the applicant's website are hereby incorporated by reference as further background information on rotor and centrifugal mills into the subject matter of this disclosure.

[0006] It is an object of the invention to provide a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which avoids or at least reduces potential operating errors by the user.

[0007] Another aspect of the object of the invention is to provide a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which avoids or at least reduces unnecessary cleaning effort.

[0008] Another aspect of the object of the invention is to provide a laboratory mill for grinding materials, in particular a rotor or centrifugal mill, which is better suited for expensive and / or pollutant-containing samples or avoids or at least reduces environmental risks.

[0009] Another aspect of the object of the invention is to provide a laboratory mill for grinding material, in particular a rotor or centrifugal mill, which on the one hand ensures safe operation and on the other hand can still be operated in the event of selected malfunctions, as long as the malfunctions are not safety-relevant.

[0010] The object of the invention is achieved by the subject matter of the independent claims. Advantageous embodiments of the invention are defined in the dependent claims.

[0011] According to one aspect of the invention, a laboratory mill for crushing or grinding material, in particular a rotor or centrifugal mill, is provided. The laboratory mill comprises a housing with a housing cover, which seals a grinding chamber inside the housing from the environment, an electric drive motor, and a grinding assembly that can be inserted into the grinding chamber. The housing cover can, in particular, be designed as a hinged hood.

[0012] The grinding assembly comprises a grinding rotor, which is driven by the drive motor, a stationary, annular counter-element that can be arranged coaxially directly around the grinding rotor, an annular sample collection container, and a collection container lid that seals the sample collection container when it is located inside the grinding chamber during operation. The collection container lid is preferably a loose, separate inner lid, independent of the housing lid, which can be handled individually by the user, e.g., for thorough cleaning.

[0013] The shredding rotor can, for example, comprise an annular array or colonnade of circumferential vertical impact teeth extending from a base disk, e.g., vertically or parallel to the axis of rotation, in a peripheral edge region. Depending on the shredding rotor, the stationary annular counter-element can be designed, for example, as an annular screen, annular impact bar, or annular counter-blade insert. The material to be ground is shredded, for example, by the impact, collision, and / or shear action of the rotating shredding rotor, e.g., by the high-speed rotating impact teeth in a cylindrical peripheral edge region of the shredding rotor, or between the shredding rotor, or more precisely the impact teeth, and the annular counter-element, e.g., the annular screen, which coaxially surrounds them cylindrically.

[0014] The sample collection container features, in particular, a peripheral circumferential ring wall and an annular base with a central hole. The sample collection container and its lid can form a cassette, closed in the peripheral ring area, which can be inserted into the grinding chamber and may optionally already include an annular counter-element and / or grinding rotor.

[0015] The grinding assembly defines a central rotor chamber arranged radially inside the stationary annular counter element, in which the comminution rotor rotates, and a peripheral annular sample collection chamber arranged radially outside the stationary annular counter element, in which the comminuted material can be collected.

[0016] The stationary, annular counter-element, in particular, separates the central rotor chamber from the peripheral, annular sample collection chamber. In other words, the stationary, annular counter-element forms a circumferential inner boundary, the peripheral circumferential ring wall a circumferential outer boundary, and / or the annular base of the sample collection vessel a lower boundary of the peripheral, annular sample collection chamber.

[0017] During operation of the laboratory mill, the comminution rotor, driven by the electric drive motor, rotates in the central rotor chamber in such a way that the material to be ground, which is introduced into the central rotor chamber, is comminuted by impact, collision and / or shearing or cutting action by the comminution rotor or between the comminution rotor, e.g. impact rotor, collision rotor or cutting rotor, and the stationary annular counter element, and the comminutioned material thus passes radially outwards through the stationary annular counter element, e.g. a ring sieve into the peripheral annular sample collection chamber.

[0018] According to one aspect of the present invention, the laboratory mill comprises a sample container lid sensor device that detects the presence and / or correct seating of the sample container lid on the sample container within the grinding chamber. This ensures that the sample container lid has been correctly placed on the sample container by the user and is correctly seated within the grinding chamber, which is sealed by the housing lid, when the grinding process is started. For example, a protective circuit may be included that prevents the grinding process, i.e., the start of the drive motor, from starting if the sample container lid is not correctly positioned or has even been completely forgotten by the user.

[0019] In practice, it has been observed that users sometimes forget to replace the sample container lid before closing the housing lid. However, operating without the sample container lid does not pose a safety risk, as the housing lid seals and secures the grinding chamber, and therefore safety regulations do not require this. Operating without the sample container lid, however, can lead to extensive contamination of the entire grinding chamber and the outside of the sample container when the laboratory mill is switched on. This is because the ground material can fly out of the sample container and spread throughout almost the entire grinding chamber, resulting in extensive and highly undesirable cleaning. The present invention eliminates this potential for user error, thus preventing unnecessary cleaning efforts due to such errors.

[0020] Furthermore, it may happen that the user grinds environmentally hazardous substances. The user wears protective clothing during this process. If the sample is added to a conventional rotor mill – without a collection container lid – an uncontrolled release of the pollutant into the environment could occur, as the sample collection container is not sealed. The ground sample can then escape from the laboratory mill in all directions, as the device housing or grinding chamber is not airtight. This disadvantage can also be avoided with the present invention.

[0021] Furthermore, it may be necessary to grind up very expensive samples. Such samples are typically used in relatively small quantities. For example, one gram of a sample can potentially cost several thousand euros. If such a valuable sample were carelessly ground up without a collection container lid, significant financial losses could occur. This disadvantage can also be avoided with the present invention.

[0022] The collection container lid features, in particular, a substantially horizontally extending lid plate and a centering ring extending downwards from a peripheral edge of the lid plate, which encircles the outer surface of the sample collection vessel. The sensor device on the lid preferably engages the horizontal lid plate from above, a design that has proven to be simple and reliable.

[0023] Preferably, the collection container lid sensor device is attached or mounted on an inside of the housing lid and automatically comes into close proximity to the collection container lid or the lid plate when the housing lid is closed, in order to detect the presence and / or correct seating of the collection container lid on the sample collection container in the grinding chamber when the housing lid is closed.

[0024] According to a preferred design of the laboratory mill, it additionally features a housing lid sensor device that detects the closed state of the housing lid. This prevents the grinding process from starting if the housing lid is not closed and / or prevents the housing lid from being opened while the laboratory mill is still in operation.

[0025] Preferably, the laboratory mill comprises a control unit with a program controller for controlling the grinding process and a user input device via which the user can enter grinding parameters for the grinding process, e.g., grinding time, rotor speed, pauses, etc. The program controller is specifically designed to control the grinding process in response to the grinding parameters entered by the user. Furthermore, the program controller can be configured to query the collection container lid sensor device and / or the housing lid sensor device and, based on the result of the query from the collection container lid sensor device, to start the grinding process or to prevent the grinding process from starting, particularly despite a user-initiated start command.

[0026] Preferably, the collection container lid sensor device defines a release state, which corresponds to the correct seating of the collection container lid on the sample collection container, and a protection state, which corresponds to the absence and / or incorrect seating of the collection container lid on the sample collection container. The program control is designed to start the grinding process after a user start input for the grinding process if the release state is present, and to prevent the start of the grinding process despite the user start input if the protection state is present.

[0027] According to a preferred embodiment, the program control has a user override function that allows the user to manually override the prevention of the grinding process starting when the protection state is present at the user input device. This allows the user to start the grinding process by activating the user override function, even though the program control has detected the presence of the protection state. This has the advantage that the user can continue to use the laboratory mill even if the collection container lid sensor malfunctions, for example, due to a defect or contamination, and is not necessarily dependent on an immediate service technician. Furthermore, the laboratory mill remains compliant with the Machinery Directive, as the absence of the collection container lid does not pose a safety risk because the housing lid is closed for operation.Moreover, the risk of unwanted contamination can still be reduced, as the conscious activation of the user override function creates a special sensitivity for the user to check that the collection container lid is correctly seated.

[0028] According to a preferred embodiment, the laboratory mill includes a housing lid sensor device that detects the closed state of the housing lid. The collection container lid sensor device defines a release state, which corresponds to the correct seating of the collection container lid on the sample collection container, and a protection state, which corresponds to the absence and / or incorrect seating of the collection container lid on the sample collection container. The housing lid sensor device defines an open state, which corresponds to an open position of the housing lid, and a closed state, which corresponds to a closed position of the housing lid.The program control is designed to start the grinding process after a user start input if a combination of the closed state and the release state is present, and to prevent the start of the grinding process if at least one of the protection state and / or the open state is present.

[0029] The user override function is now designed so that the user can manually override the prevention of the grinding process starting when the protection state is present at the user input device. This allows the user to start the grinding process even though the program control has detected the protection state, but only if the program control detects that the housing cover is closed. This reconciles maximum safety with protection against unwanted contamination on the one hand, and continued operation in compliance with machine directives in the event of a malfunction of non-safety-related functions on the other.

[0030] Preferably, the collection container lid sensor device and / or the housing lid sensor device each comprise at least one contact sensor, one optical sensor, one NFC sensor or one reed contact, which, when the collection container lid is correctly seated on the sample collection container, comes into close proximity to the collection container lid in the grinding chamber when the housing lid is closed.

[0031] In other words, the collection container lid sensor is located in the housing lid. If the housing lid is closed and no collection container lid is detected, the laboratory mill is prevented from starting up by the software control. The sensor function of the collection container lid sensor can be implemented, for example, via contacts such as spring contacts, optical sensors, NFC sensors, reed contacts, or similar devices. By checking the presence of the collection container lid and the subsequent start-up prevention mechanism, incorrect operation can be prevented.

[0032] The collection container lid preferably has an electrically conductive surface; for example, it is made of stainless steel with an electrically conductive surface. The collection container lid sensor device can, for example, comprise one or more spring contacts which, when the collection container lid is correctly seated on the sample collection container, spring-loaded to contact the lid within the grinding chamber and establish an electrical connection to the lid when the housing lid is closed.

[0033] Preferably, the collection container lid sensor device can have two spring contacts which are electrically or galvanically connected to each other via the collection container lid by means of electrical contact, such that the program control can detect a current flow through the two spring contacts and the collection container lid.

[0034] This has proven to be both simple and robust in application under the specific laboratory conditions of a rotor or centrifugal mill.

[0035] In particular, the housing cover has an axial central filling funnel and / or the collection container cover has an axial central opening into which the filling funnel opens, such that the user can feed material to be ground from outside the laboratory mill into the rotor chamber through the filling funnel and / or the central opening in the collection container cover during operation, in order to continuously grind the material. The filling funnel can seal against the collection container cover when the housing cover is closed for the grinding process, so that no material can escape at this interface.

[0036] According to a preferred embodiment, the device housing has a substantially horizontal partition or intermediate floor between the grinding chamber and a lower motor compartment in which the drive motor is installed. The intermediate floor, in turn, has a central opening through which a rotor drive shaft extends vertically into the grinding chamber. The rotor drive shaft can, for example, be the motor shaft itself or an extension of the motor shaft. Preferably, the rotor drive shaft and the grinding rotor have complementary drive elements, such as transverse bolts and a corresponding transverse groove, such that the grinding rotor can be placed onto the rotor drive shaft from above in the grinding chamber and driven by the rotor drive shaft in a rotating manner by means of the drive elements.A ring seal, in particular a labyrinth seal, can be arranged around the rotor drive shaft between the grinding rotor and the drive motor. This seal seals the rotor chamber and / or the peripheral annular sample collection chamber or the interior of the sample collection container against the lower motor chamber to prevent contamination of the motor chamber with ground material. The labyrinth seal can have concentric, complementary labyrinth rings on the underside of the grinding rotor and on the top side of a stationary labyrinth disc, which engage with each other when the grinding rotor is mounted onto the rotor drive shaft.

[0037] Before grinding, the necessary components of the rotor or centrifugal mill are typically assembled as follows: first the labyrinth disc, then the grinding rotor, then the sample collection container for the ground sample, then the ring sieve, and finally the lid of the sample collection container. Of course, a different assembly sequence is also possible. If the user forgets to attach the lid to the sample collection container before grinding, the housing cover can still be closed. With a conventional rotor or centrifugal mill, the mill can be started, and the user adds the sample to the grinding process through the sample feed hopper. Since the sample collection container is not closed at this point, the ground sample is distributed throughout the entire upper chamber of the mill. This results in a lengthy and time-consuming cleaning process.The present invention advantageously avoids such incorrect operation.

[0038] Preferably, the housing cover has a motorized interlock or a motorized locking mechanism that is controlled and / or monitored by the program control, thereby increasing safety and / or ease of use for the user.

[0039] The invention will now be explained in more detail with reference to exemplary embodiments and the figures, whereby identical and similar elements are partially provided with the same reference numerals and the features of the different exemplary embodiments can be combined with one another. Brief description of the characters

[0040] They show: Fig. 1 a front view of an exemplary embodiment of a laboratory mill, Fig. 2 A side view from the right of the laboratory mill Fig. 1 Fig. 3 a three-dimensional representation of the laboratory mill made of Fig. 1 with exploded view of the grinding assembly, Fig. 4 an excerpt from Fig. 3, Fig. 5 a three-dimensional representation of an exemplary interior of a laboratory mill, Fig. 6 a cross-sectional view along line 6-6 in Fig. 1, Fig. 7 a cross-sectional view along line 7-7 in Fig. 2, Fig. 8 a horizontal cut along the line 8-8 in Fig. 1, Fig. 9 a cross-sectional view along line 9-9 in Fig. 8, Fig. 10 a view of the underside of the laboratory mill Fig. 1 with partially hidden floor grid, Fig. 11 A side view from the left of the laboratory mill Fig. 1, Fig. 12 a sectional view along line 12-12 in Fig. 11, Fig. 13 an enlarged sectional view of the grinding assembly made of Fig. 12, Fig. 14 a top view of the laboratory mill Fig. 1 with hidden case cover, Fig. 15 a top view of the laboratory mill Fig. 1 with partially hidden case cover, Fig. 16 a cross-sectional view along line 16-16 in Fig. 15, Fig. 17a a section enlargement from Fig. 16, Fig. 17b a section enlargement with exploded view of the collection container lid sensor device, Fig. 18 a cross-sectional view along line 18-18 in Fig. 15, Fig. 19a a section enlargement from Fig. 18, Fig. 19b a close-up with exploded view of the housing cover sensor assembly, Fig. 20 a cross-sectional view of a section of the laboratory mill made of Fig. 1, Fig. 21 a partially cut-away three-dimensional representation of the laboratory mill made of Fig. 1, Fig. 22 a close-up from Fig. 21, Fig. 23 a close-up similar to Fig. 22, seen from the front, Fig. 24 a cutaway view of the laboratory mill from Fig. 1 with the case cover slightly open, Fig. 25 a close-up from Fig. 24, Fig. 26 a schematic functional sequence of a grinding process. Detailed description of the invention

[0041] The Fig. Figures 1 to 4 show a laboratory mill 1, which in the present embodiment is designed as a rotor mill or so-called high-speed rotor mill. The rotor mill 1 has a housing 30, which includes a lower base housing 32 that can be placed on a laboratory table by means of feet 34. The housing 30, or the base housing 32, can be closed with a pivoting lid 36 on the top of the base housing 32. The lid 36 has a feed hopper 38 into which material to be ground can be fed into the rotor grinding mechanism during operation of the rotor mill 1. A user input device 40, e.g., in the form of a touch display 42 and a rotary knob 44, is located on the top of the base housing 32, via which the user can program and control the rotor mill 1.For example, the user can enter the grinding duration, speed, grinding pauses or other process parameters dependent on the material being ground or the grinding task via the 42-inch touch display and start the grinding process.

[0042] The rotor mill 50 comprises a comminution rotor 52 rotating about a vertical axis of rotation A, which is, for example, designed as a percussion rotor, and a stationary annular counter element in the form of an annular screen 54 in which the comminution rotor 52 rotates coaxially. The comminution rotor 52 and the annular screen 54 are positioned in a sample collection container 56 and divide the interior of the sample collection container 56 into a central rotor chamber 62, in which the comminution rotor 52 rotates and comminsulates the material to be ground, and a peripheral annular sample collection chamber 64, in which the comminuted material is collected. For the grinding process, the user feeds the sample or material to be ground axially into the central area of ​​the comminution rotor 52 via the material feed hopper 38. The material to be ground is accelerated radially outwards in the comminution rotor 52 by centrifugal force.In a peripheral ring region of the comminution rotor 52, there is an annular colonnade arrangement 58 consisting of a plurality of impact teeth 66, which comminute the material to be ground at high speed by means of impact, collision, and / or shear action. The material can also be partially comminuted between the impact teeth 66 and the annular screen 54. The comminuted material can then pass radially outwards through the openings (not shown) of the annular screen 54 and enter the annular sample collection chamber 64. Optionally, the comminuted material can also be extracted by a suction device (not shown) which can be connected to a suction port 70. The suction port 70 is clearly optional, and other grinding assemblies or sample collection containers 56 do not have a suction port; instead, the annular shell 56a of the sample collection container 56 is completely closed.

[0043] The annular sample collection container 56 is closed at the top with a collection container lid 72. The grinding assembly 74 is thus formed from the sample collection container 56, the collection container lid 72, and the impact rotor 52 and ring screen 54 arranged in the closed sample collection container 56. The sample collection container 56 can be removed from the rotor mill 1 with or without the attached collection container lid 72, for example, to handle the ground material outside the rotor mill 1 or to clean the grinding assembly. The collection container lid 72 has a central sample filling opening 78 into which the filling funnel 38 opens axially when the housing lid 36 is closed, in order to feed the ground material into the grinding rotor 52 during operation.

[0044] The grinding chamber 98 is bounded on the underside by an intermediate floor 96 as a partition to the lower motor chamber 134 and on the upper side by the hood-shaped housing cover 36. The grinding rotor 52 has concentric labyrinth rings 82 on its underside, which together with corresponding concentric labyrinth rings 84 of the labyrinth disc 80 form a disc-shaped labyrinth seal 86 (cf. Fig. 13, Fig. 14) When inserting the grinding assembly 74 into the rotor mill 1, the user can first place the labyrinth disc 80 onto an annular mantle 92, which projects coaxially from the intermediate floor 96 of the grinding chamber into the grinding chamber 98. The annular mantle 92 and the attached labyrinth disc 80 together form a central hat-shaped or truncated cone-shaped dome structure 94 on the intermediate floor 96 of the grinding chamber 98. The parts of the grinding assembly 74 can be placed onto the dome structure 94 in the grinding chamber 98, and then the grinding chamber is closed by folding and locking the housing cover 36 to start the grinding process.

[0045] Referring to the Fig. Figure 6-14 shows that the rotor mill 1 has a drive motor 102, the motor shaft 104 of which runs vertically and forms the central axis A of the rotor mill 1. The shredding rotor 52 can be axially mounted onto a rotor drive shaft 106, which in the present embodiment can be the motor shaft 104 itself, and can be driven in a rotating manner by a transverse bolt 108, which is attached to a lower drive extension 112 of the shredding rotor 52 by means of a transverse groove 110.

[0046] An electric cooling fan 114 is positioned below the drive motor 102, preferably coaxially with the drive motor 102. The cooling fan 114 draws in fresh cooling air through a base plate 116 of the device housing 30 and generates a cooling airflow, schematically symbolized by arrows 138, which is directed vertically upwards towards the drive motor 102 and flows axially upwards along the drive motor 102. For this purpose, the base plate 116 has a bottom grille 118 below the cooling fan 114. The bottom grille 118 is spaced from the laboratory table on which the rotor mill 1 stands by the feet 34, in order to draw in fresh cooling air from the side under the base plate 116 and from there through the bottom grille 118 into the interior of the device housing 30, more precisely into the lower motor compartment 134, and blow it axially upwards towards the drive motor 102.

[0047] To generate a directed cooling airflow 138 axially along the drive motor 102, the drive motor 102 in this example has a motor housing 122, which defines vertical or axial first cooling air channels 124 in the exterior of the motor housing 122 or in a motor housing jacket 123. In this example, the motor housing 122 is essentially square in horizontal section and has a total of four vertical first cooling air channels 124 at its corners. These channels are aerodynamically aligned with the electric cooling fan 114 and directly receive the cooling airflow 138 directed vertically upwards by the cooling fan 114. Within the first cooling air channels 124, they direct the airflow upwards around the motor, thus effectively cooling the drive motor 102. In other words, the cooling fan 114 blows the cooling air into the first cooling air channels 124.In the present example, the volume flow rate of the cooling airflow is approximately 255 m³ / h. 3 / h.

[0048] In the present embodiment, the drive motor 102 with its motor housing 122 is installed in a vertically extending axial cooling air guide tube 126. The cooling air guide tube 126 surrounds the motor housing 122 at a radial distance, so that an annular space or gap 128 is formed between the drive motor 102 or the motor housing 122 and the cooling air guide tube 126. In the present example, the cooling air guide tube 126 has a rectangular cross-section. It is evident, however, that the cooling air guide tube can also have a different cross-sectional shape, e.g., round. Cooling air in the form of a directed cooling airflow 138 can also be guided axially upwards along the drive motor 102 through the annular space 128. In the present example, the annular space 128 surrounds the entire drive motor 102 in a ring shape, so that a relatively large cooling airflow 138 can be guided within it.the flow resistance in the space 128 is relatively small.

[0049] At the upper end of the drive motor 102, the cooling airflow 138 can exit the first cooling air channels 124 and / or the annular space 128 and enter second cooling air channels 132. The second cooling air channels 132 extend through the intermediate floor 96 from the lower motor compartment 134 into the upper grinding chamber 98. Otherwise, the upper grinding chamber and the lower motor compartment 134 are preferably largely separated by the intermediate floor 96, which forms a horizontal partition between the upper grinding chamber 98 and the lower motor compartment 134, in order to prevent contamination in the lower motor compartment 134. Accordingly, the first cooling air channels 124 and / or the annular space 128 surrounding the motor housing 122 together with the second cooling air channels 132 form a common cooling air channel system or cooling air flow system, which extends from the cooling fan 114 on the base plate 116 of the device housing 30 up into the upper grinding chamber 98.The cooling fan 114 draws in cooling air through the base plate 116 from outside the device housing 30 and blows it into the cooling air duct system, which directs the cooling airflow 138 vertically and axially upwards along the drive motor 102 and from there through the horizontal intermediate floor 96 between the upper grinding chamber 98 and the lower motor compartment 134 into the upper grinding chamber 98. From the upper grinding chamber 98, the cooling air can escape to the outside into the environment through an outlet grille 120, e.g., in the housing cover 36. Fig. 20).

[0050] In other words, the total cooling airflow 138 in the lower engine compartment 134 comprises a first cooling airflow 138a in the axial first cooling air channels 124 in the engine housing 123 and a parallel second cooling airflow 138b in the space or annular space 128 between the engine housing 122 and the cooling air guide tube 126. The cooling airflows 138a and 138b are guided axially upwards along the drive motor 102 separately from each other by the cooling air channel system. In this example, both cooling airflows 138a and 138b are recombined in the upper region of the drive motor 102 and then flow together into the second cooling air channels 132, which are connected in series with it.

[0051] In particular, the cooling airflow 138 is directed from the second cooling air ducts 132 between the lower motor compartment 134 and the upper grinding chamber 98 under the sample collection vessel 56, specifically under its annular base 60. When the grinding assembly 74 is installed, the annular base 60 extends in a ring around the dome structure 94, on which the comminution rotor 52 rotates and is sealed by means of the labyrinth seal 86. For this purpose, the dome structure 94, or the annular shell 92 rising from the intermediate base 56, has, for example, elongated milled cooling air passage openings 136, which lead radially outwards from the interior of the dome structure 94 under the base 60 of the sample collection vessel 56. In other words, the cooling air flows from the second cooling air channels 132 under the labyrinth disc 80 into the interior of the dome structure 94 under the labyrinth disc 80 and from there through the radial cooling air openings 136 ( Fig. 3, Fig. 4) under the bottom 60 of the sample collection container 56. This allows for efficient cooling of both the drive motor 102 and the grinding assembly 74, and thus of the material being ground, during and, if necessary, after grinding.

[0052] The rotor mill 1 is controlled by a control unit 142 with a program controller. The control unit 142 is connected to the user input device 40, and the program controller receives and processes the grinding parameters entered by the user. The program controller of the control unit 142 controls, for example, the rotational speed of the rotor mill and the start and stop of the grinding process, monitors safety devices such as the locking mechanism of the housing cover 36, and, if necessary, monitors or controls a variety of other functions of the rotor mill 1. The program controller also controls the electric cooling fan 114, in particular its switching on and off. For example, the program controller can be configured to allow the electric cooling fan 114 to continue running with a run-on control after the grinding process has already ended, i.e., after the drive motor 102 has already stopped.The overrun control can be predefined as part of a standard operating procedure (SOP) and / or requested by the user as a parameter via the user input device 40, if required for the specific grinding task. This means that the user can, for example, enter the overrun command into the program control via the user input device 40, particularly before the start command for the grinding process, and, if necessary, also define the overrun time quantitatively. The rotor mill 1 then starts the drive motor 102, allowing the user to grind their sample. After the drive motor 102 stops, the program control automatically allows the cooling fan 114 to continue running for a predetermined overrun time to further cool the drive motor 102 and the sample collection container 56 after the grinding process has ended. This can be advantageous, among other things, for the subsequent handling of the grinding assembly 74. For example,Immediately after the drive motor 102 stops, the grinding assembly 74 may still be too hot to be removed from the device housing 30 by the user. Due to the run-on time and the associated post-cooling, which is automatically performed by the program control after the drive motor 102 stops, the user can, if necessary, attend to other tasks while the drive motor 102 and the sample collection container 56 continue to cool down, and this occurs more quickly than if only the housing cover 36 were opened. Furthermore, if necessary, the drive motor 102 can also be cooled further after the user has already removed the grinding assembly 74. This increases the efficiency of using the rotor mill 1.

[0053] In summary, the control unit 142 contains a program control which can control the electric cooling fan 114 independently of the grinding process or independently of the drive motor 102.

[0054] A first temperature sensor 144 can be arranged below the sample collection container 56, which determines the temperature of the sample collection container 56 and thus indirectly the temperature of the material being ground. A second temperature sensor (not shown) can measure the temperature of the drive motor 102. In this example, the drive motor 102 has three second temperature sensors, which are located directly in the windings U, V, and W. In this example, the second temperature sensors can only switch in binary mode, I / O. This means that if the temperature exceeds 135°C, the drive motor 102 is switched off. The program control can be configured to read the first and / or second temperature sensor and control the grinding process in response to the temperature readings from the first and / or second temperature sensor. For example, the program control can be configured to control an interval grinding process using the measured temperature values.The program control can be configured to automatically switch off the drive motor 102 when the temperature reading at the first and / or second temperature sensor exceeds a predefined temperature threshold value T1max or T2max, respectively, which is stored in a memory of the control unit. The program control then continues to operate the electric cooling fan 114, at least until the predefined threshold values ​​for the first and / or second temperature reading are no longer exceeded. This also increases the efficiency of mill operation, as it reduces the time required for the sample collection vessel 56, and thus the material being ground and / or the drive motor 102, to cool down sufficiently, for example, for handling the grinding container and / or for the next grinding process.

[0055] To further improve post-cooling, the housing cover 36 can be equipped with a pop-up mechanism 150 which, after the drive motor 102 stops, causes the housing cover 36 to pop open slightly, as shown in the Fig. 24, Fig. 25 is shown.

[0056] The housing cover 36 is held closed or locked, for example, by a motorized interlock 152. The motorized interlock 152 is controlled and monitored by the program control, so that the grinding process can only be released when the motorized interlock 152 of the housing cover 36 is in the closed safety position (see figure). Fig. 21-23).

[0057] After the drive motor 102 stops, the program control can automatically open the interlock 152. The housing cover 30 can include an actuator 154 that partially, but preferably not completely, opens the housing cover 36. This allows the laboratory mill 1 to automatically open the housing cover 36 partially, or to a gap, after the grinding process has finished, allowing the warmed cooling air to escape even more effectively from the upper grinding chamber 98. For this purpose, one or more actuators 154 are preferably provided in the area of ​​the cover hinges 158, e.g., one actuator 154 on each side of the housing cover 36. In the illustrated embodiment, the actuators 154 are designed as spring-loaded snap locks, which may not retract deeply enough to engage when the housing cover 36 is closed. As a result, the spring-loaded snap locks constantly press their roller 156 downwards, generating an opening force on the housing cover 36.To close the housing cover 36, the user pushes the cover downwards against the preload of the actuators 154. The motorized locking mechanism 152 then pulls the cover further and locks it in place, ensuring the grinding process can be started safely. Additionally, torsion springs (not shown) can be provided in the cover hinges 158 to assist in lifting the housing cover 36 with the feed hopper 38. Furthermore, spring-loaded rotor locking pins 162 can be provided in the housing cover 36 to mechanically block the grinding rotor 52 from starting if the user forgets to put the collection container cover 72 on. When the collection container cover 72 is placed on the sample receiving container 56, the spring-loaded rotor locking pins 162 bear against the cover and thus assist in lifting the housing cover 36.

[0058] The grinding process can therefore proceed as follows: With the housing cover 36 open, the user inserts the grinding assembly 74 into the upper grinding chamber of the rotor mill 1. First, the labyrinth disc 80 can be placed on top, and then the grinding rotor 52 can be mounted onto the rotor drive shaft 106, whereby the labyrinth rings 82 of the grinding rotor 52 engage axially with the labyrinth rings 84 of the labyrinth disc 80 to form the labyrinth seal 86. The ring-shaped counter-element, e.g., ring sieve 54, can then be placed around the comminution rotor 52, e.g., on an outer edge of the labyrinth disc 80. The sample collection container 56, with its central opening 57 in the base 60, can then be placed over the comminution rotor 52 and, if applicable, the ring sieve 54, whereby the sample collection container 56 is also placed over the dome structure 94 on the intermediate floor 96 of the inner grinding chamber 98.Finally, the collection container lid 72 can be placed on the sample collection container 56 and, if necessary, sealed with a ring seal 73 and an annular peripheral ring rim 75. For some grinding assemblies 74, a different insertion sequence may be required; for example, in some grinding assemblies, the grinding rotor 52 and / or the ring sieve 54 can be completely removed from the upper grinding chamber 98 and reinserted. The housing lid 36 is then closed or pivoted shut, with the lower end 39 of the filling hopper 38 engaging with the central sample filling opening 78 of the collection container lid 72. Furthermore, the housing lid 36 is, if necessary, tightened and locked by the retaining clip 152.

[0059] The user can either pre-program the grinding parameters for several grinding tasks or do so individually before or after closing the housing cover 36. Parameters such as speed, grinding duration, grinding pauses, and the overrun itself, as well as any overrun time, can be programmed. The user then starts the grinding process and feeds the material to be ground through the feed hopper 38 into the interior of the grinding unit 74 towards the grinding rotor 52. When the grinding process is complete, the program control first stops the drive motor 102, but allows the cooling fan 114 to continue running for the programmed overrun time. Furthermore, after the drive motor 102 stops, the program control can automatically open the locking mechanism 152, allowing the cooling fan 114 to continue running even longer.By opening the locking mechanism 152, the actuators 154 can open the housing cover 56 slightly, thus further improving the efficiency of the post-cooling. When the post-cooling time has elapsed, the program control automatically stops the cooling fan 114.

[0060] Referring to the Fig. In the laboratory mill 1, a housing cover sensor device 202 is located between the base housing 32 and the housing cover 36. This device monitors the closed state of the housing cover 36. A collection container cover sensor device 212 is provided between the housing cover 36 and the collection container cover 72. This device detects the presence and / or correct seating of the collection container cover 72 on the sample collection vessel 56 within the upper grinding chamber 98 when the housing cover 36 is closed. In this example, both sensor devices 202 and 212 are designed as double spring contacts, which allow current flow by contacting a conductive surface. The first spring contacts 204 of the housing cover sensor device 202 are preferably arranged on a lower edge 36a, for example, in the front region of the housing cover 36 opposite the cover hinges 158 of the housing cover 30.When the housing cover 36 is swung shut, the spring contacts 204 come into contact with an electrically conductive counter plate 206, spring back slightly, and the circuit between the two spring contacts 204 is automatically closed via the counter plate 206 when the user closes the housing cover 36.

[0061] The sample container lid sensor device 212, or its second spring contacts 214, is preferably arranged on an inner surface 36b of the housing lid, specifically in the area of ​​the sample container lid 72. When the user closes the housing lid 36, the sample container lid sensor device 212 detects the presence or correct seating of the sample container lid 72 on the sample container 56, as the sensor device 212 comes within close proximity to the sample container lid 72. In this example, the spring contacts 214 automatically come into contact with a top surface 72a of the sample container lid 72 when the housing lid 36 is closed. The sample container 56, and in particular the sample container lid 72, preferably have an electrically conductive surface, for example, made of bare stainless steel sheet.This establishes a galvanic contact between the two spring contacts 214 of the collection container lid sensor device 212 and the upper surface 72a of the collection container lid 72. The program control monitors the current flow through the sensor devices 202 and / or 212 and detects whether the housing lid 36 is closed and / or whether the collection container lid 72 is present in the upper grinding chamber 98 and correctly positioned on the sample collection container 56. The program control is designed to enable the start of the grinding process or the drive motor 102 only when the housing lid sensor devices 202 signal the closed state and the collection container lid sensor device signals the enabled state. In this example, both sensor devices 202 and 212 are designed with spring contacts that allow current flow via galvanic contact.However, the sensor devices 202 and / or 212 may also include other sensor devices, such as optical sensors, an NFC sensor or reed contacts.

[0062] The collection container lid 72 preferably consists of an annular lid plate 72b surrounding the central filling opening 78 and a peripheral ring rim 72c that runs annularly around the lid plate 72b to center the collection container lid 72 on the sample collection container 56 and in which the ring seal 73, preferably in the form of an O-ring, is attached to seal against the upper ring rim 56a of the sample collection container 56. The collection container lid sensor device 212 is preferably arranged above the lid plate 72b, so that in the present embodiment the second spring contacts 214 automatically come into contact with the lid plate 72b when the housing lid 36 is closed.

[0063] If the housing cover sensor 202 signals neither a closed nor an open state, this constitutes safety-relevant information, so the program control prevents the drive motor 102 from starting, and the user cannot override this. The presence or absence of the collection container lid 72, however, does not represent a safety-relevant function, so the collection container lid sensor 212 does not represent any safety functions. Therefore, the program control can have an override function that allows the user to manually override the prevention of the drive motor 102 starting or the grinding process, for example, by entering an override command at the user input device 40.The advantage lies in the fact that the user can still operate the laboratory mill 1 if the collection container lid sensor device 212 malfunctions, and is not immediately dependent on a service technician. Since an incorrectly seated or missing collection container lid 72 serves only to detect an operating error, which is intended to prevent contamination of the grinding chamber 98, but cannot endanger the user because the safety-relevant housing cover 36 remains closed (and no override function is available for it), deactivating the detection of the collection container lid 72 by manual override by the user complies with the Machinery Directive.

[0064] Fig. Figure 26 shows a simplified example of the functional sequence of a grinding process.

[0065] In step 302, the program control waits for the insertion of the complete grinding assembly 74. An animation on the touch display 42 can show the sequence in which the grinding rotor 52, the ring sieve 54, the sample collection container 56, and / or the collection container lid 72 should be inserted. These animations can be dynamically adjusted if necessary.

[0066] In step 304, the program control prompts the user via the touch display 42 to close the housing cover 36.

[0067] In step 306, the program control uses the collection container lid sensor device 212 to check whether the collection container lid 72 has been inserted correctly.

[0068] When the program control has determined that the collection container lid 72 has been correctly inserted, the program control in step 308 controls the safety interlock, closing the locking hook of the tether 152.

[0069] When the program control receives the feedback from the safety interlock or the locking mechanism that it is "closed", the program control waits in step 310 for the user to enter the start command.

[0070] After the user has entered the start command on the touch display 42, the program control in step 312 activates the cooling fan 114 and releases safety circuits.

[0071] After the program control receives the signal “safety ok” from the frequency converter, the program control starts the drive motor 102 in step 314.

[0072] After the user-programmed grinding time has elapsed or after the user has entered a stop command for the grinding process, the program control stops the drive motor 102 in step 316.

[0073] After the program control receives the feedback speed “-0” from the frequency converter, the program control checks in step 318 whether an automatic unlocking should take place or whether there is an unlocking command from the user.

[0074] If the result in step 318 is positive, the program control sends an unlock command to the locking mechanism in step 320 and the interlock 152 opens.

[0075] After the safety interlock has reported "open" to the program control, the program control checks in step 322 whether a run-on time is programmed, e.g., as a SOP or through individual user programming. If not, the cooling fan 114 stops and the program control jumps back to the initial step 102 in step 324; if so, the cooling fan 114 continues to operate in step 326 (run-on time).

[0076] In step 328, the program control monitors whether the overrun time has elapsed. If so, the cooling fan 114 is stopped in step 330 and the program control jumps back to the initial step 102.

[0077] It is evident to the person skilled in the art that the embodiments described above are to be understood as examples and that the invention is not limited to them, but can be varied in many ways without departing from the scope of protection of the claims. Furthermore, it is evident that the features, regardless of whether they are disclosed in the description, the claims, the figures, or otherwise, also individually define essential components of the invention, even if they are described together with other features. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 100 22 849 A1

[0004] DE 100 66 027 A1

[0004] DE 10 2012 010 065 A1

[0004] DE 20 2012 013 666 U1

[0004] DE 20 2012 013 667 U1

[0004]

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