Abstract: The invention relates to a fluid dynamic bearing system particularly for the purpose of rotatably supporting a spindle motor, having a first bearing part that comprises a bearing sleeve, and a second bearing part that comprises a shaft, the two bearing parts being spaced apart from one another by a bearing gap and being rotatable with respect to each other, wherein the bearing sleeve is closed at one end by a counter plate that is accommodated in an annular recess in the bearing sleeve and connected to the bearing sleeve by a welded joint. According to the invention, a bearing system is provided in which the counter plate has a reduced thickness (D2) at its outer edge and is welded in the region of its reduced thickness (D2) to the bearing sleeve. The reduced thickness of the counter plate at the region of its outer edge means that the vertical gap between the bearing sleeve and the counter plate is made very much shorter, or is done away with altogether, so that no unwanted air can remain in the gap.

Abstract: The invention relates to a piezoelectric drive unit and a method for generating a preferably rotating drive movement for such a drive unit. The drive unit comprises a stator (1), a rotor, embodied to rotate about a rotational axis (2), with relation to the stator and drive elements, preferably in the form of several piezoelectric actuators (8). The drive unit further comprises an annular gap (4?), filled with a fluid medium (10), arranged between the facing surfaces of the stator (1) and the rotor (2), several piezoelectric actuators (8a, 8d), arranged adjacent to the gap, which perform an essentially radial length change in the direction of the gap (4?) on electrical activation, such that the mechanical energy, provided by the actuators, is transformed into flow energy of the fluid medium, whereby the flow energy of the fluid medium is transmitted to the rotor (2) and transformed into a rotating drive movement of the rotor.

Abstract: A method for filling the bearing gap of a hydrodynamic bearing with a lubricant, where drops of lubricant are produced in a defined manner and are applied to a defined region of the bearing to be filled.

Abstract: The invention relates to a spindle motor having a hydrodynamic bearing system, particularly to drive platters in a hard disk drive, the platters being disposed on a rotor, and the bearing system being formed by a bearing sleeve arranged on a baseplate and a shaft rotatably supported in an opening in the bearing sleeve and at least one thrust plate connected to the shaft. A liquid lubricant is filled into a bearing gap formed between the shaft, the thrust plate and the bearing sleeve. The invention is characterized in that the thrust plate rests directly against the rotor and is accommodated in an annular recess in the bearing sleeve facing the rotor.

Abstract: The invention relates to a piezoelectric drive unit and a method for generating a preferably rotating drive movement for such a drive unit. The drive unit comprises a stator (1), a rotor, embodied to rotate about a rotational axis (2), with relation to the stator and drive elements, preferably in the form of several piezoelectric actuators (8). The drive unit further comprises an annular gap (4?), filled with a fluid medium (10), arranged between the facing surfaces of the stator (1) and the rotor (2), several piezoelectric actuators (8a, 8d), arranged adjacent to the gap, which perform an essentially radial length change in the direction of the gap (4?) on electrical activation, such that the mechanical energy, provided by the actuators, is transformed into flow energy of the fluid medium, whereby the flow energy of the fluid medium is transmitted to the rotor (2) and transformed into a rotating drive movement of the rotor.

Abstract: A fluid dynamic bearing assembly including a shaft and a bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve and is filled with a lubricating fluid. A capillary seal is formed at one end of the bearing sleeve, and a recess is formed in the shaft immediately above the capillary seal. The surface of the recess forms an acute angle with an axis of the shaft.

Abstract: A device to measure a fluid dynamic bearing system, particularly the inside diameter of the bearing bore of a bearing sleeve or the outside diameter of a shaft using a sensor element. A capacity acting sensor element is used to determine, for example, the inside diameter of the bearing bore, the sensor element being designed as part of the surface of a shaft prepared for measurement purposes. To determine the outside diameter of the shaft, the sensor element is correspondingly designed as part of the surface of the bearing bore of a bearing sleeve prepared for measurement purposes. Means of introducing a measuring fluid, preferably compressed air, into the bearing gap remaining between the bearing sleeve and the shaft are provided so that during the measurement process the shaft is automatically aligned and centered within the bearing bore.

Abstract: A hydrodynamic bearing system, having a bearing sleeve and a shaft inserted into an inner cylindrical bore of the bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve, the bearing gap being filled with a lubricating oil. A shield encloses the bearing sleeve. The shield is secured within a recess formed at the top surface of the bearing sleeve at a position distanced from the bearing gap. The shield is pressed against a sharp edge of the recess by a metal ring placed into the recess.

Abstract: A hydrodynamic bearing system, having a bearing sleeve and a shaft inserted into an inner cylindrical bore of the bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve, the bearing gap being filled with a lubricating oil. A shield encloses the bearing sleeve. The shield is secured at to an end surface of the bearing sleeve at a position on the end surface that is distanced from the bearing gap. The shield does not contact the lubricating oil.

Abstract: The invention relates to a fluid dynamic bearing system particularly for the purpose of rotatably supporting a spindle motor, having a first bearing part that comprises a bearing sleeve, and a second bearing part that comprises a shaft, the two bearing parts being spaced apart from one another by a bearing gap and being rotatable with respect to each other, wherein the bearing sleeve is closed at one end by a counter plate that is accommodated in an annular recess in the bearing sleeve and connected to the bearing sleeve by a welded joint. According to the invention, a bearing system is provided in which the counter plate has a reduced thickness (D2) at its outer edge and is welded in the region of its reduced thickness (D2) to the bearing sleeve. The reduced thickness of the counter plate at the region of its outer edge means that the vertical gap between the bearing sleeve and the counter plate is made very much shorter, or is done away with altogether, so that no unwanted air can remain in the gap.

Abstract: The invention relates to a method to optically measure the filling level of a liquid in a cavity having a sub-mm wide opening with the aid of a measuring sensor based on chromatic coding, the measuring sensor delivering a distance value and an intensity value as its output signal. The method is characterized by the steps: Recording a distance profile and an intensity profile of the surface of the liquid by moving the measuring sensor along the opening of the cavity holding the liquid, the movement being made essentially parallel to the surface of the fluid along a measurement segment x, and determining the filling level by means of a combined analysis of the recorded distance profile and intensity profile.

Abstract: A device to measure a fluid dynamic bearing system, particularly the inside diameter of the bearing bore of a bearing sleeve or the outside diameter of a shaft using a sensor element. A capacity acting sensor element is used to determine, for example, the inside diameter of the bearing bore, the sensor element being designed as part of the surface of a shaft prepared for measurement purposes. To determine the outside diameter of the shaft, the sensor element is correspondingly designed as part of the surface of the bearing bore of a bearing sleeve prepared for measurement purposes. Means of introducing a measuring fluid, preferably compressed air, into the bearing gap remaining between the bearing sleeve and the shaft are provided so that during the measurement process the shaft is automatically aligned and centered within the bearing bore.

Abstract: The invention relates to a spindle motor having a hydrodynamic bearing system, particularly to drive platters in a hard disk drive, the platters being disposed on a rotor, and the bearing system being formed by a bearing sleeve arranged on a baseplate and a shaft rotatably supported in an opening in the bearing sleeve and at least one thrust plate connected to the shaft. A liquid lubricant is filled into a bearing gap formed between the shaft, the thrust plate and the bearing sleeve. The invention is characterized in that the thrust plate rests directly against the rotor and is accommodated in an annular recess in the bearing sleeve facing the rotor.

Abstract: A hydrodynamic bearing system, having a bearing sleeve and a shaft inserted into an inner cylindrical bore of the bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve, the bearing gap being filled with a lubricating oil. A shield encloses the bearing sleeve. The shield is secured within a recess formed at the top surface of the bearing sleeve at a position distanced from the bearing gap. The shield is pressed against a sharp edge of the recess by a metal ring placed into the recess.

Abstract: A method of verifying and inspecting the bearing gap between a shaft and a shaft seat of a hydrodynamic bearing includes positioning the shaft in its functional position in the shaft seat of the test bearing. A measuring fluid is then caused to flow through the bearing gap. One or more parameters characterizing the fluid flow through the bearing gap can then be measured. Because these parameters of the fluid flow are affected by the dimensions of the bearing gap, the bearing gap can thus be reliably verified. A corresponding device for verifying and inspecting the bearing gap is also provided.

Abstract: The invention relates to a method to optically measure the filling level of a liquid in a cavity having a sub-mm wide opening with the aid of a measuring sensor based on chromatic coding, the measuring sensor delivering a distance value and an intensity value as its output signal. The method is characterized by the steps: Recording a distance profile and an intensity profile of the surface of the liquid by moving the measuring sensor along the opening of the cavity holding the liquid, the movement being made essentially parallel to the surface of the fluid along a measurement segment x, and determining the filling level by means of a combined analysis of the recorded distance profile and intensity profile.

Abstract: A hydrodynamic bearing system, having a bearing sleeve and a shaft inserted into an inner cylindrical bore of the bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve, the bearing gap being filled with a lubricating oil. A shield encloses the bearing sleeve. The shield is secured at to an end surface of the bearing sleeve at a position on the end surface that is distanced from the bearing gap. The shield does not contact the lubricating oil.

Abstract: A method for filling the bearing gap of a hydrodynamic bearing with a lubricant, where drops of lubricant are produced in a defined manner and are applied to a defined region of the bearing to be filled.

Abstract: A method of verifying and inspecting the bearing gap between a shaft and a shaft seat of a hydrodynamic bearing includes positioning the shaft in its functional position in the shaft seat of the test bearing. A measuring fluid is then caused to flow through the bearing gap. One or more parameters characterizing the fluid flow through the bearing gap can then be measured. Because these parameters of the fluid flow are affected by the dimensions of the bearing gap, the bearing gap can thus be reliably verified. A corresponding device for verifying and inspecting the bearing gap is also provided.

Abstract: A fluid dynamic bearing assembly including a shaft and a bearing sleeve. A bearing gap is formed between the shaft and the bearing sleeve and is filled with a lubricating fluid. A capillary seal is formed at one end of the bearing sleeve, and a recess is formed in the shaft immediately above the capillary seal. The surface of the recess forms an acute angle with an axis of the shaft.