Spindle motor with fluid dynamic bearing system

Abstract

The invention relates to a spindle motor with a fluid dynamic bearing system, comprising a stationary motor component (12, 14, 22) and a motor component (16, 20, 24, 38) rotatably mounted by means of the fluid dynamic bearing system, and an electromagnetic drive system (42, 44) for driving the rotatable motor component (16, 20, 24, 38), wherein the rotatable motor component (16, 20, 24, 38) has a rotor component (24, 38) which is at least partially designed as a stamped part, a deep-drawn part, or an extrusion part.

Description

[0001] The invention relates to a spindle motor with a fluid dynamic bearing system according to the preamble of claim 1.

[0002] Spindle motors with fluid dynamic bearing systems for driving hard disk drives, fans, laser scanners, and other devices are known in a wide variety of designs.

[0003] Such spindle motors comprise a stationary motor component and a rotating motor component. The rotating motor component includes, for example, a shaft and a rotor component connected to the shaft, which carries the load to be driven. It is known to manufacture the rotor component from solid material, usually steel or aluminum, using machining processes.

[0004] Due to the high material usage and complex machining, the machining of rotor components for spindle motors is time-consuming and costly.

[0005] The purpose of the invention is to reduce the manufacturing costs of a spindle motor mentioned above.

[0006] This problem is solved by a spindle motor with the features of claim 1.

[0007] The spindle motor with a fluid dynamic bearing system comprises a stationary motor component and a motor component rotatably mounted by means of the fluid dynamic bearing system and an electromagnetic drive system for driving the rotatable motor component.

[0008] According to the invention, the rotatable motor component has a rotor component which is at least partially designed as a stamped part, deep-drawn part or extrusion part.

[0009] Preferred embodiments of the invention are disclosed in the dependent claims.

[0010] In a preferred embodiment of the invention, the rotor component comprises a bearing component connected to a shaft and a hub. According to the invention, the hub is manufactured very cost-effectively from sheet steel or aluminum, since it has no surfaces that require high-precision machining. Therefore, after stamping or deep drawing, no complex post-processing of the hub is generally necessary.

[0011] Preferably, the hub is connected to the bearing part by means of a press fit and / or adhesive bond and / or welded connection. Each connection type can be used individually or in combination with one or more other connection types.

[0012] In a preferred embodiment of the invention, the hub has an axially extending inner rim, the inner circumferential surface of which is connected to an outer circumferential surface of the bearing component. Preferably, the hub is pressed onto the bearing component and can additionally or alternatively be secured by means of an adhesive bond.

[0013] In another preferred embodiment, the hub can rest on and be connected to the bearing component by means of a radially extending inner section. Here, a press fit and / or adhesive bond can again be used. Alternatively, a welded connection between the hub and the bearing component is possible.

[0014] In another embodiment of the invention, the bearing component can have an axially extending outer edge, the inner circumferential surface of which, together with an outer circumferential surface of the bearing bushing, defines a sealing gap of the fluid-dynamic bearing system. The sealing gap seals the bearing gap of the bearing system, which is filled with bearing fluid, from the external environment.

[0015] According to a further preferred embodiment of the invention, the hub can have an axially extending inner section, the inner circumferential surface of which, together with an outer circumferential surface of the bearing bushing, defines a sealing gap of the fluid dynamic bearing system. Thus, the bearing component can be designed very simply, since it is not required for forming the sealing gap, which reduces costs.

[0016] In another preferred embodiment of the invention, the entire rotor component can be manufactured as a flow-formed part. This rotor component is directly connected to the shaft, and a separate bearing component is not required.

[0017] The spindle motor can be used in particular to drive a fan, wherein the fan wheel of the fan has an outer rim that rests on an outer flange of the hub, wherein an inner circumferential surface of an outer rim of the fan wheel is connected to an inner circumferential surface of an outer rim of the hub.

[0018] Alternatively, the fan wheel of the fan can have a preferably flat underside that rests on and is connected to a preferably flat top side of the hub.

[0019] In both of the above-mentioned cases, the connection between the fan wheel and the hub can preferably be designed as an adhesive connection.

[0020] The spindle motor according to the invention can also be used to drive laser scanners or hard disk drives.

[0021] Preferred embodiments of the invention are described in more detail below with reference to the drawings, and further features and advantages of the invention are explained. Fig. Figure 1 shows a first preferred embodiment of the spindle motor. Fig. Figure 1A shows an enlarged detail of Fig. 1. Fig. Figure 1B shows a second preferred embodiment of the spindle motor. Fig. Figure 1C shows an enlarged detail of Fig. 1B. Fig. Figure 2 shows a third preferred embodiment of the spindle motor. Fig. 2A shows an enlarged detail of Fig. 2. Fig. Figure 3 shows a fourth preferred embodiment of the spindle motor. Fig. 3A shows an enlarged detail of Fig. 3. Fig. Figure 4 shows a fifth preferred embodiment of the spindle motor. Fig. Figure 4A shows an enlarged detail of Fig. 4. Fig. Figure 5 shows a sixth preferred embodiment of the spindle motor. Fig. 5A shows an enlarged detail of Fig. 5. Fig. Figure 6 shows a seventh preferred embodiment of the spindle motor. Fig. Figure 6A shows an enlarged detail of Fig. 6.

[0022] The construction of the spindle motor will now be described using the following examples: Fig. 1 described in more detail. This basic structure applies to all illustrated designs of the spindle motor.

[0023] The spindle motor comprises a retaining bushing 12, which is mounted in a base plate 10. The retaining bushing 12 is preferably positively connected to the base plate 10 by means of a press-fit method. To increase the strength of the connection, an adhesive can be additionally used, applied either locally or circumferentially to the connection point. The adhesive penetrates the gap between the base plate 10 and the retaining bushing 12 by capillary action, thereby reinforcing the positive fit of the connection. The base plate 10 can be part of a housing of a device driven by the spindle motor, for example, a fan.

[0024] The retaining bushing 12 has a cylindrical opening in which a cylindrical bearing bushing 14 is mounted. The bearing bushing 14 is fixed in the retaining bushing 12, for example, by means of adhesive.

[0025] A shaft 16 is rotatably mounted in a bearing bore of the bearing bushing 14. An axially extending section 18a of a bearing gap 18 is formed between the shaft 16 and the bearing bushing 14, which is filled with a bearing fluid, for example, a bearing oil.

[0026] At one lower end, the shaft 16 has a bearing plate 20, which is received in a corresponding recess in the bearing bushing 14. The recess of the bearing bushing 14 and the bearing bore are hermetically sealed at this end by a cover 22.

[0027] The bearing plate 20 is freely rotatable in the recess of the bearing bushing 14, which is closed by the cover 22. A radially extending section 18b of the bearing gap 18 is formed between the lower end face of the bearing bushing 14 and the upper end face of the bearing plate 20. This section is connected to the axially extending section 18a of the bearing gap 18 and is filled with bearing fluid.

[0028] Between the underside of the bearing plate 20 and the top of the cover 22 there is also a gap 18d, which is filled with bearing fluid and connected to the bearing gap 18.

[0029] A ring-shaped bearing component 24 is attached to a free end of the shaft 16 that protrudes from the bearing bushing 14. This bearing component forms part of the rotor component and rotates together with the shaft 16 during operation of the spindle motor.

[0030] A lower end face of the bearing component 24 borders the upper end face of the bearing bushing 14 and is separated from it by a further radially extending section 18c of the bearing gap 18, which is connected to the axially extending section 18a of the bearing gap 18 and is filled with bearing fluid.

[0031] The upper, radially extending section 18c of the bearing gap 18 is sealed by means of a capillary sealing gap 26, so that no bearing fluid can escape from the bearing gap 18. The sealing gap 26 extends in the axial direction and is bounded by an outer circumferential surface of the bearing bushing 14 and an inner circumferential surface of a circumferential edge 24a of the bearing component 24.

[0032] The fluid dynamic bearing system has at least one fluid dynamic radial bearing, preferably two fluid dynamic radial bearings 28, 30, and preferably two fluid dynamic axial bearings 32, 34.

[0033] The two fluid-dynamic radial bearings 28, 30 are arranged along the axially extending section 18a of the bearing gap at a mutual axial distance between the shaft 16 and the bearing bushing 14. The associated bearing surfaces on the shaft 16 or the bearing surfaces on the bearing bushing 14, or both bearing surfaces, are provided with micrometer-fine bearing groove structures which, when the shaft 16 rotates in the bearing bushing 14, generate a pumping effect on the bearing fluid located in the axial section 18a of the bearing gap 18, so that a hydrodynamic pressure builds up in the section 18a of the bearing gap 18.

[0034] To absorb the axial load, two fluid-dynamic axial bearings 32 and 34 are provided. The first fluid-dynamic axial bearing 32 is arranged along the radially extending section 18c of the bearing gap 18 between associated bearing surfaces of the upper end face of the bearing bushing 14 and the lower end face of the bearing component 24. The second fluid-dynamic axial bearing 34 is arranged along the radially extending section 18b of the bearing gap 18 between associated bearing surfaces of the bearing plate 20 and the lower end face of the bearing bushing 14.

[0035] Both fluid-dynamic axial bearings 32, 34 are provided on one or both bearing surfaces with micrometer-fine bearing groove structures which, when the bearing plate 20 or the bearing component 24 is rotated relative to the bearing bushing 14, generate a pumping effect on the bearing fluid located in the radial sections 18b, 18c of the bearing gap 18, so that a hydrodynamic pressure builds up in the sections 18b and 18c of the bearing gap 18.

[0036] A recirculation channel 36, which runs obliquely in the axial direction through the bearing bushing 14, connects the transition area between the upper radial section 18c of the bearing gap 18 and the sealing gap 26 directly with the gap sections 18b and 19 on the outer circumference of the bearing plate 20 and is completely filled with bearing fluid. The recirculation channel 36 thus ensures good circulation of the bearing fluid and pressure equalization in the bearing gap 18.

[0037] A hub 38 is attached to the bearing component 24, which together with the bearing component 24 forms the complete rotor component and carries the load to be driven. The in Fig. 1 The ring-shaped hub 38 shown is manufactured according to the invention as a stamped or deep-drawn part from sheet steel and has an approximately U-shaped cross-section.

[0038] How to find out, especially in Fig. As can be seen from Figure 1A, an axially extending inner rim 38a of the hub 38 is fitted onto the bearing component 24 and sits on a step of the bearing component 24, such that the upper end face of the hub 38 is flush with the top surface of the bearing component 24. The connection between the hub 38 and the bearing component 24 is preferably designed as a press fit and may additionally or alternatively include an adhesive bond.

[0039] The retaining bushing 12, the bearing bushing 14 and the cover 22 as well as the stator assembly 44 together form the stationary motor component of the spindle motor.

[0040] The shaft 16, the bearing plate 20, the bearing component 24, the hub 38 and the rotor magnet 42 together form the rotatable motor component of the spindle motor.

[0041] The spindle motor can be used to drive a fan wheel 40 mounted on the hub 38. The hub 38 comprises an axially extending outer rim 38b, the lower end of which has a radially outwardly angled flange 38c. The fan wheel 40 is made, for example, of plastic and has a downwardly directed axially extending rim 40a that rests on the radial flange 38c of the hub 38 and determines the mounting position of the fan wheel 40. The fan wheel 40 is preferably attached to the outer circumferential edge 38b of the hub 38 by means of an adhesive, with its axially extending rim 40a.

[0042] The electromagnetic drive system of the spindle motor comprises a rotor magnet 42, which is arranged on an inner circumferential surface of the axially extending outer edge 38b of the hub 38. The hub 38 is preferably made of ferromagnetic steel sheet and simultaneously forms the magnetic yoke and the magnetic return path for the rotor magnet 42. The rotor magnet 42 is radially opposite a stator assembly 44, which is attached to an outer seat of the retaining bushing 12.

[0043] The Fig. Figures 1B to 6A show modified versions of the spindle motor. Fig. 1 and Fig. 1A, whereby the basic structure is the same in each case. Identical components are marked with the same reference numerals. In the following drawings, only the essential differences to the Fig. 1 and Fig. 1A described.

[0044] The Fig. 1B and Fig. 1C shows a spindle motor which, unlike the Fig. 1 and Fig. 1A has no external radial flange 38c on the hub 38. The fan wheel 40 rests with its underside directly on the top side of the hub 38 and is preferably bonded to the hub 38 by means of adhesive.

[0045] The Fig. 2 and Fig. Figure 2A shows a variant of the invention in which the inner, axially extending rim 38a of the hub does not rest on a step of the bearing component 24, but projects axially beyond the underside of the bearing component 24. The rim 38a of the hub projecting beyond the underside of the bearing component 24, together with the outer circumferential surface of the bearing bushing 14, forms the boundary for the capillary sealing gap 26. This design allows for a simpler and more cost-effective design of the bearing component 24, which can be manufactured as a simple cylindrical component.

[0046] Since the edge 38a of the hub 38 comes into contact with bearing fluid in the sealing gap, it must be attached to the outer circumferential surface of the bearing component 24 with a liquid-tight adhesive to prevent bearing fluid from escaping the sealing gap. Additionally, a press fit can be provided between the edge 38a of the hub 38 and the bearing component 24.

[0047] The fan wheel 40 rests with its outer axial edge 40a on the radial flange 38c of the hub 38 and does not touch the upper end face of the hub 38.

[0048] The Fig. 3 and Fig. 3A shows a variant that is essentially the same as the design of Fig. 1 and Fig. 1A corresponds to this. The ring-shaped hub has an approximately L-shaped cross-section. The attachment of the hub 38 to the bearing component 24 is achieved differently, in that the inner edge of the hub 38 is not angled in the axial direction, but rests flat on a step of the bearing component 24 and is fixed there by means of adhesive. In addition, a press fit can be provided between the hub 38 and the bearing component 24.

[0049] The Fig. 4 and Fig. Figure 4A shows an embodiment of the spindle motor in which the inner horizontal edge of the hub 38 is connected to the bearing component 24 by means of a weld. This can be achieved using several weld points distributed around the circumference or a continuous, continuous weld seam. Preferably, a laser welding process is used.

[0050] In the variant of Fig. 5 and Fig. 5A also provides a welded connection which is not located in the impact area between the hub 38 and the bearing component 24, but the hub 38 is placed on the bearing component 24 and connected to the bearing component 24 by a fusion-welded spot weld.

[0051] The Fig. 6 and Fig. Figure 6A shows an embodiment of the invention in which the bearing component is an integral part of the hub 138. The integral hub 138 is manufactured using a flow-forming process.

[0052] In this case, post-processing of the hub 138 may be necessary, at least in the area of ​​the bearing surface of the upper axial bearing 32. However, the creation of a connection between the hub 138 and a bearing component is not required. The hub 138 has a radial flange 138c on which the edge of the fan wheel 40 rests. List of reference symbols 10 Base plate 12 Retaining socket 14 Bearing bushing 16 wave 18 Bearing gap (ad) 18a, b, c, d Sections of the bearing gap 20 bearing plate 22 lids 24 Bearing component 24a Rand 26 capillary sealing gap 28 fluid dynamic radial bearing 30 fluid dynamic radial bearing 32 fluid dynamic axial bearing 34 fluid dynamic axial bearing 36 Recirculation channel 38 hub 38a inner edge 38b outer edge 38c flange 40 fan wheel 40a outer edge 42 Rotor magnet 44 Stator arrangement 138 hub 138c flange

Claims

[1] Spindle motor with a fluid dynamic bearing system comprising a stationary motor component (12, 14, 22) and a motor component rotatably mounted by means of the fluid dynamic bearing system (16, 20, 24, 38, 138), and an electromagnetic drive system (42, 44) for driving the rotatable motor component (16, 20, 24, 38, 138), characterized by , that the rotatable motor component (16, 20, 24, 38, 138) has a rotor component (24, 38, 138) which is at least partially designed as a stamped part, deep-drawn part or extrusion part. [2] Spindle motor according to claim 1, characterized by , that the rotor component has a bearing component (24) connected to a shaft (16) and a hub (38) connected to the bearing component (24), wherein the hub (38) is designed as a stamped part or deep-drawn part. [3] Spindle motor according to one of claims 1 or 2, characterized by, that the hub (38) is connected to the bearing component (24) by means of a press connection and / or adhesive connection and / or weld connection. [4] Spindle motor according to any one of claims 1 to 3, characterized by , that the hub (38) has an axially extending inner edge (38a) whose inner circumferential surface is connected to an outer circumferential surface of the bearing component (24). [5] Spindle motor according to any one of claims 1 to 3, characterized by , that the hub (38) rests on the bearing component (24) with a radially extending inner section and is connected to it. [6] Spindle motor according to any one of claims 1 to 5, characterized by , that the bearing component (24) has an axially extending outer edge (24a) whose inner circumferential surface together with an outer circumferential surface of the bearing bushing (14) defines a sealing gap (26) of the fluid dynamic bearing system. [7] Spindle motor according to any one of claims 1 to 5, characterized by, that the hub (38) has an axially extending inner section (38a) whose inner circumferential surface together with an outer circumferential surface of the bearing bushing (14) defines a sealing gap (26) of the fluid dynamic bearing system. [8] Spindle motor according to claim 1, characterized by , that the entire rotor component (138) is designed as a flow-formed part. [9] Fan with a spindle motor according to any one of claims 1 to 8, characterized by , that it has a fan wheel (40) with an outer rim (40a) which rests on an outer flange (38c, 138c) of the hub (38) or rotor component (138), wherein an inner circumferential surface of an outer rim (40a) of the fan wheel (40) is connected to an inner circumferential surface of the outer rim (38b) of the hub (38) or rotor component (138). [10] Fan with a spindle motor according to any one of claims 1 to 8, characterized by, that the fan wheel (40) has a bottom side which rests on and is connected to a top side of the hub (38) or rotor component (138). [11] Laser scanner with a spindle motor according to any one of claims 1 to 8. [12] Hard disk drive with a spindle motor according to any one of claims 1 to 8.

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