JPS5917018A - Fluid bearing device utilizing dynamic pressure type lubricating oil - Google Patents

Abstract

PURPOSE:To obtain a bearing, whose rigidity and frictional moment are almost not changed even at low and high temperatures, by providing an oil reservoir groove to a part, where the maximum pressure is generated at rotation of a shaft, of the parts forming grooves. CONSTITUTION:A ring shaped oil reservoir groove 36 is provided in at least either one of the periphery of a shaft 22 or the internal periphery of a sleeve 23 to the central part of a herringbone groove, that is, to a part, where the maximum pressure is generated at rotation of the shaft, and lubricating oil is held by surface tension or the like in said groove 36. At high temperature, though a bearing clearance C3 is increased by thermal expansion of a metallic material such as the shaft 22 and the sleeve 23 or the like, volumetric expansion of lubricating oil larger than the thermal expansion of the metallic material causes the lubricating oil to be filled in an overall width of the grooved part, and sufficient rigidity is obtained. Further, because the viscosity of the lubricating oil is decreased, the frictional momentcan be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dynamic pressure type lubricating oil type hydrodynamic bearing device, and particularly relates to a hydrodynamic bearing device with a high temperature. A conventional hydrodynamic bearing used in the O-Video 79 Ngu, which aims to obtain a hydrodynamic fluid bearing device with excellent 1+J properties and in which the bearing rigidity and bearing If friction moment hardly change even at low or high temperatures. The apparatus is shown in Figures 1-3. Identification / The cylinder 1 is made of iron-based metal / Sleeve 3 is made of copper-based metal, on which two nafts 2 are attached, and the rotating tram and head 6 are attached to the shaft 2.
is taken and turned off at the same time. A thrust bearing 6 is fixed to one end of the shaft 2.
A thrust receiver 8 is screwed to the sleeve 3 so as to cover the sleeve 3. At the center of the end of the thrust bearing 8, there is a single-row spiral group (hereinafter referred to as group) with a depth of 4 to 10 microns in the pattern shown in FIG. A double-row spiral group shown in C9 is provided, respectively, and constitutes a thrust bearing. Similarly, the shaft 2 is provided with a herringbone type group 2a at the upper part and a similar group 2b at the lower part of the motor 11111, forming a radial bearing. Furthermore, the four group portions mentioned in "2" are filled with lubricating oil 9 such as oil or grease. Also sleeve 3
The rotor 10 of the motor 13 is fixed several times, the stator 11 of the motor 13 is attached to the fixing/ring=1, and the motor 13 is energized. The rotating part starts rotating.

However, in conventional hydrodynamic bearings of this type, the 9th to 1st
As shown in diagram A in Figure 9, the viscosity of 6 lubricating oil increases significantly at low temperatures due to poor temperature viscosity characteristics of lubricating oil (oil or grease). The bearing support force becomes larger than necessary, resulting in excessive quality, and the bearing friction moment becomes extremely large as shown in No. 101a#, especially when using a VT for porta-pull.
If a hydrodynamic bearing device is used in R, the VTR must be driven by a battery with a relatively small capacity, so the disadvantage is that the operating time of 1J per battery is shortened.

Previous efforts have been made to solve this problem/ζ1
One method is to improve the temperature viscosity retention of the lubricating oil itself. For example, there is a method-C that uses 1q/recon oil with good temperature viscosity 1m't4+ properties as a lubricating oil.
This I'I cannot completely improve the bearing moment l- at low temperatures, and moreover, the contact angle of the oil itself is small, and therefore the contact angle of the oil itself is small. It has the serious drawback that it oozes out naturally, and it is difficult to completely prevent this. There is a method that makes use of the difference in linear expansion coefficients between the two. 1. Use the shaft 2 and the thrust bearing 6 made of brass, aluminum, plastic, etc. with a linear expansion coefficient, and use the sleeve 3.
By using the monthly coefficient of iron-based linear expansion,
This method improves the temperature characteristics of the bearing friction torque of a hydrodynamic bearing device by setting the bearing clearances - jc1, C2, and C3 of each part shown in Figure 1 to be small at high temperatures and large at low temperatures. In actual design, it is difficult to select a material with high surface hardness and a large elastic modulus for the shaft 2 and thrust bearing 6 from among materials with a large coefficient of linear expansion marked -F. If brass or the like is selected for the shaft bearing 6 or the thrust bearing 6, it tends to be damaged during the assembly process, and the shaft 2 has serious drawbacks such as increased deflection and inferior structural rigidity. .

The present invention is intended to solve the drawbacks of the prior art described in C. and B. Examples thereof will be described below with reference to FIGS. 4 to 10.

FIG. 4 shows the dynamic pressure type lubricant type hydrodynamic bearing device of the present invention for use in a VTR. This is an example used in a 'under. A fixing ll+l 1122 is press-fitted into the center of the lower cylinder 21, and a t'' sleeve 23 is rotatably inserted into the fixed shaft 22 constituting the identification side unibody 20, and a thrust receiver 28, The first part/cylinder 24 and the magnetic head 25 are attached to form the other side unit 27. i, j If, IJ on the F part of the ma/ko sleeve 23
A rotary transformer 32 on the other side is installed, and a fixed flai 10-tally transformer 34 is installed on the T-section norinder 21 opposite to it. In addition, several armature magnets 35 with circumferences χ and J of the same type direct drive element and a cup-shaped magnet case 30 are cut into the sleeve 23 which has been cut out. 30.33.35 constitutes a circumferential direct drive motor 31.

Identification IIqb 22 is etched at two places on the top and F part of the V-V (by which, herringbone-shaped groups 22A and 22B with a depth of 5 to 20 micrometers are processed,
By controlling the radial clearance to the inner diameter of the sleeve 23 to 6 to 10 microns and applying lubricating oil 29 of approximately 20 to 100 centipoise or a slightly higher viscosity grease thereto, the radial fluid bearing can be installed. Configure. Dimension fixing 111+ 220 The tip surface is precisely machined to be flat and at right angles. A flange-shaped thrust bearing 26 is provided on the sleeve 23 and is screwed to the sleeve 23, and the thrust bearing has a single row spiral group as shown in FIG. A double-row spiral group shown in FIG. 8 is etched on the lower surface of the sleeve 23 facing the end surface of the sleeve 23, and by applying an appropriate amount of oil to each group, a thrust direction fluid bearing 4o is formed. The unit 27 is levitated. Note that the shape of the spiral group shown in Figure 7 may be V''1, or it may be a double-row shape as shown in Figure 8, and the spiral group of this type may be machined on the -1-face of the thrust bearing. That's true. 1, either the center of the upper surface of the thrust bearing 26 or the center of the upper surface of the thrust bearing 28 has an oil storage groove 37 on one side.
However, an oil storage groove 38 is provided on either the lower surface of the thrust shaft bearing or the corresponding end of the sleeve 23.

5-6 are detailed views of a herringbone radial bearing. At the center of the helical bone type group, that is, at the part where the force is highest during rotation, a ring-shaped oil reservoir 36 is attached to the outer periphery of the shaft 22 or to at least one of the inner diameters of the sleeve 23. ,3e
Figure 5 (a) shows a state of high temperature (for example, 6o'C), in which the lubricating oil is held by surface tension, etc. In this case, the shaft 22, sleeve 23, etc. metal 4
Although the bearing clearance C3 may be larger than the thermal expansion scale of 1 year old I, the volume expansion of the lubricating oil is much larger than that of the metal monthly rate, so the entire width W of the lubricating oil d group part is When it becomes full and either the sleeve 23 or the gift 22 rotates! Sufficient 111il stiffness due to loop bombing action? () will be
・At high temperatures, the viscosity of the lubricating oil becomes low (As shown in Figure 9B, the friction of the bearing is small, which is essential for the drive motor, and does not result in a large load. , Fig. 6(b) and Fig. 6(b) show the fluid force component IJ.It has an approximately E-angular shape, and lit is l1l.
This corresponds to the supporting force of an r-bearing.

Figure 6 (a) is a state diagram at low temperatures (for example -20'C), and the bearing clearance C3 may become slightly smaller due to contraction of the metal material, but the lubricating oil contracts more than that. However, some groups will not be lubricated with lubricating oil. When rotation starts in this state, the lubricating oil is gradually collected between the line G and σ of the middle heat part of the herringbone type grip as shown in Figure 6 due to the pumping action of the group, forming a hydrodynamic bearing with an effective width WL. Sufficient rigidity is obtained when the specified number of rotations is reached. At low temperatures,
Even if the viscosity of the lubricating oil increases/the effective width WL is small, almost the same rigidity as at high temperatures can be obtained, and the bearing friction moment hardly changes compared to at high temperatures, as shown in the diagrams in Figures 9 and 10. Bearing friction moment as shown in B!・And bearing support force (
A hydrodynamic bearing with excellent temperature characteristics in terms of bearing rigidity and ζ dynamic pressure type lubrication can be obtained.

What is shown in FIG. 6(B) is the pressure distribution of the fluid, and since its substantially king-shaped area is the same as that in FIG. 6(B), it can be seen that both have the same bearing rigidity.

Now, the reason why the lubricating oil storage groove is provided here is that unless the lubricating oil level is increased to a certain level, the volume change of the lubricating oil will not be sufficient. Based on the old calculations, taking into consideration the volume V of the miso, the usage in!1 degree range of the fluid 1111, the volumetric expansion coefficient of the lubricating oil, the difference in the linear expansion coefficient of the shaft 22 and the sleeve 23, the width of the required loop, etc. demand.

lY','When lubricating 1m oil, lubricate by hanging with a reliable old m-meter under constant temperature conditions, but as an alternative method, apply /1: oil in a slight line and -11 , a method in which the temperature is increased by 1-r and the lubricating oil overflows into the wide gap parts E and D shown in Fig. 5 (a) is also possible by forming a convex lubricating oil storage groove which is capable of nJ. The reason why it is provided in the part of the group where the force is highest is that there is a pumping effect in which the lubricating oil is forcibly collected in the part where the pressure/J is the highest during rotation.

In the small group part, as shown by the arrow in Figure 6 (a), the gap is very narrow, 5 to 10 microns, compared to the part marked E, so the lubricant MW oil flows out due to its own surface tension V. It is not stored in the group section.

The above description has been about radial bearings, but the temperature characteristics of thrust bearings can be improved as follows.

As shown in FIG. 7(a), the thrust receiver is a single-row spiral group provided on the lower surface of part 280.

In the center of the group, a blind hole-shaped oil storage groove 37 having an appropriate volume is provided. At high temperatures, the lubricating oil expands and spreads throughout the groove as indicated by arrows H and H', while at low temperatures, the lubricating oil contracts and does not spread over the entire surface. Then, when it rotates, it expands in the area indicated by the dotted line in the figure. In this way, as with the radial direction bearing, the effective diameter of the group becomes smaller at low temperatures, so a hydrodynamic bearing with a bearing friction moment that does not change at low temperatures or high temperatures can be obtained. FIG. 7(b) shows the pressure distribution, which shows that the bearing supporting force is almost the same at both low and high temperatures.

What is shown in FIG. 8(A) is a plurality of spiral groups provided on the lower surface of the thrust bearing 26. A load 38 in the form of a ring is provided at the part where the IL force is highest during rotation, and the load 38 is 4"l. ) j m oil is stored at J'ji ℃ - In this case as well, even though the t, J, and Tsukuda 1 clearances may increase at high temperatures, the lubricating oil 1; extends throughout the groove to H, H”.

On the other hand, at low temperatures, L and L' contract to a point smaller than the dotted circle, so the bearing friction moment hardly changes at low or high temperatures, and there is no excessive load on the low-temperature-C motor. By making improvements to the thrust bearing in this way, the temperature characteristics can be further improved.

Note that, although not shown in Figures 7 and 8, the storage groove is located opposite the group.
In other words, the same applies to the upper surface of the thrust bearing 26 and the opposing surface of the thrust bearing 23 of the sleeve 23.2 According to the present invention, the pressure of the group is highest in the radial and thrust direction hydrodynamic bearings. By providing an oil storage groove in the bearing, a dynamic pressure lubricating oil type fluid bearing with excellent temperature characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional hydrodynamic bearing device, Figs. 2 and 3 are group shape diagrams in the same device, Fig. 4 is a sectional view of a hydrodynamic bearing device according to an embodiment of the present invention, and Fig. 6 (A). is a cross-sectional view of the main part of the same radial bearing, FIG. 5 (rIl is a fluid pressure distribution diagram of the same bearing, FIG. ) is a fluid pressure distribution diagram of the same bearing, FIG. 7(a) is a plan view of the thrust bearing, and FIG.
b) is a fluid pressure distribution diagram of the same bearing part, Fig.
23... Sleeve, 26... Thrust bearing, 28... Thrust bearing part, 29... Feed oil, 36.36', 37.38... ...Oil storage ditch. Name of agent Patent attorney Toshi Nakao ζ1 or 1 person Figure 1 Figure 2 Figure 4 Figure 5 (4λ 3 Figure 6 Figure 7 Figure 9 → Scar (Figure 10) cliff(·..

Claims (3)

[Claims] (1) A rotating part capable of rotating and a fixed part rotatably supporting the rotating part are provided, a group is formed on either side of the rotating part and the fixed part facing each other, and ) 1V2I waste oil is provided between the shaft part and the fixed part to constitute a dynamic pressure type fluid bearing, and an oil storage groove is provided in either the fixed part or the rotating part of the part where the utility is highest during rotation. Dynamic pressure type lubricant type hydrodynamic bearing device. (2) The fixed part and the rotating part are a shaft and a sleeve rotatably provided on the PJ Tsukuda 1 on the outer periphery of this shaft, and a herringbone type group is formed on either the shaft or the sleeve. A dynamic pressure type lubricant type hydrodynamic bearing device according to claim 1. (3) The fixed part and the rotating part have a shaft end face and a thrust bearing, and the shaft end face or the thrust bearing forms a spiral group on either one of the parts.
Dynamic pressure type 45'j〆)1 Hydraulic fluid bearing device jfr according to claim 1