JPS63266209A - Dynamic pressure type fluid bearing device - Google Patents

Abstract

PURPOSE:To obtain a high bearing support load by connecting narrowed parts of the groove parts for boosting each other by means of groove parts for accumulating pressure, so as to keep boosted fluid. CONSTITUTION:A group of grooves 16 is composed of two groove parts 16A, 16B gradually narrowed as they go backward and groove parts 16C parallel to the direction of a shaft 4 (not shown). The rotation of a bearing housing 6 causes fluid to flow in along the groove parts 16A, 16B, for generating dynamic pressure, so that the fluid can be kept by means of the groove arts 16C. Consequently, the group of grooves 16 possesses boosting and pressure accumulating functions for keeping a support load, and realize the increase thereof.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a hydrodynamic bearing device.

[Conventional technology]

As a hydrodynamic bearing device, there is a herringbone groove bearing in which a groove called a herringbone is formed in a hydrodynamic bearing.
grooved bearings) are known.

The hydrodynamic bearing shape in this type of bearing device is 1, for example, '
Philips Research Report Subliment (P
HILIPS RESEARCH REPORTS SU
PPLEMENTS) “1975, P of Na’l
88 to P91 and P2O3 to P2O3. Herringbone groove bearings are either v” shaped or “
Fluid is collected inside along grooves formed in the shape of \/'' to generate dynamic pressure, and this dynamic pressure supports the rotating body.

A bearing device in which the above-mentioned groove is formed in the bearing portion has a larger bearing support load and can realize stable support compared to a bearing device in which the groove is not formed in the bearing portion.

[Problem that the invention seeks to solve]

However, it is expected that the conventional hydrodynamic bearing device as described above will be further improved in the following points.

First, in a bearing having a ``v'' shaped groove (hereinafter referred to as ``groove''), the lubricating fluid supplied between the opposing surfaces of the stationary side member and the rotating side member flows into the V groove. Dynamic pressure is generated by gathering in the center of the ■, so the allowable bearing support load is higher than a grooveless bearing, but compared to a "\/" shaped groove (hereinafter referred to as a partial groove), the allowable bearing load is higher. Bearing support load is quite small.

Next, as mentioned above, a bearing device having a partial groove has a higher bearing support load than a bearing device having a partial groove.

However, this bearing device has a poor ability to retain lubricating fluid, and when the relative rotational motion between the shaft and the bearing section decreases, the contact area between the opposing surfaces of the shaft and the bearing section becomes large. Therefore, insufficient lubricating fluid enters between the opposing surfaces, causing the shaft and bearing to come into contact and causing damage to the bearing surface, vibration and abnormal noise, especially during startup. When starting or stopping, the lubricating fluid enters the gap between the shaft and the bearing.The above-mentioned problems are likely to occur in applications where startup and stopping are frequently performed.1 For example, the head of a magnetic tape type image recording device (VTR) When a partial groove type hydrodynamic bearing device is adopted for the rotation mechanism, the above-mentioned problems are difficult to ignore.

SUMMARY OF THE INVENTION An object of the present invention is to provide a hydrodynamic bearing device that can support a large bearing load and achieve stable support.

[Means for solving problems]

According to the present invention, a groove for generating dynamic pressure is formed in either a rotating member or a stationary member disposed opposite to the rotating member, and a fluid is interposed between opposing surfaces of the rotating member and the stationary member. In a hydrodynamic bearing device that generates dynamic pressure through the rotation of a rotating member and supports the rotating member, the groove for generating the dynamic pressure described above advances in the direction of relative movement between the rotating member and the stationary member. It is characterized by being composed of pressure increasing grooves that are open on the sides and narrowing towards the rear, and pressure accumulating grooves that communicate between the narrower parts between the pressure increasing grooves.

In addition, one aspect of the present invention is to fit the shaft member and the housing member,
Fluid is interposed between the surface of the shaft member and the opposing surface of the housing member, and a groove for generating dynamic pressure is formed on either the shaft member or the housing member. This is a hydrodynamic bearing device that supports a rotating member through a rotational movement, and the groove for generating dynamic pressure has an upstream side with respect to the direction of fluid flow due to a relative rotational movement between the shaft member and the housing member. It is characterized by being composed of two slanted grooves that are open and gradually narrow on the downstream side, and a groove that communicates between the narrowest parts of the two slanted grooves in a direction orthogonal to the relative rotational motion.

[Effect]

The grooves or protrusions of the bearing device generate dynamic pressure as fluid pressure increases along the grooves or protrusions due to the rotational movement of the rotating member. Then, the pressurized fluid is held by the groove or the protrusion that communicates between the two inclined grooves. As a result, a high bearing support load can be obtained, and even when starting and stopping, fluid can easily enter between the opposing surfaces of the rotating member and the stationary member, eliminating problems caused by contact.

〔Example〕

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 shows an embodiment of the present invention, and is an embodiment in which the present invention is applied to a rotating recording mechanism section of a VTR.

The rotary recording mechanism in FIG. 1 includes a rotary cylinder 1 and a head 2 installed at the outer peripheral end of the rotary cylinder 1 and used for writing signals or reading signals recorded on a tape (not shown). ), a fixed cylinder 3 , a shaft 4 that stands up from the fixed cylinder 3 and fits into the rotating cylinder 1 , a motor (stator 13 and rotor 12 ) that generates rotational driving force, and a head 1 . One end of the shaft 4 includes a non-contact signal transmission unit (corresponding to the stator 15 and rotor 14) for transmitting and receiving signals between the signal processing unit and a signal processing unit (not shown). It is fixed in the hole provided in the center of 3 by press fit, shrink fit, etc. The other end of the shaft 4 is inserted into a hole in a bearing housing 6°, which is a bearing provided at the center of the one-rotation cylinder 1, with a small gap therebetween. As a result, the rotary cylinder 1 becomes rotatable around the shaft 4, and a radial bearing is formed between the rotary cylinder 1 and the shaft 4. A thrust bearing plate 5 for forming a thrust bearing with the end surface 7 of the shaft 4 is attached to one end (top in the figure) of the bearing housing 6 by screws. As a result, the vertical position of the rotating cylinder is regulated.A head 2 is attached to the zero-rotation cylinder 1 via a head base 9, and this head 2 slightly protrudes from the outer circumferential surface 10 of the rotating cylinder 1. It will be equipped to do so. In addition, a head 2 is attached to the cylinder 1 for one rotation.
In order to transmit the signal read by to the stationary member side,
Alternatively, a rotating side transmitting/receiving coil 14 is provided for transmitting signals sent from the stationary member side to the head 2.

A stationary side transmitting/receiving coil 15 is provided in the fixed cylinder 3 so as to face this coil 14 . Further, a rotor 12 and a stator 13 of the motor are installed facing each other in the one-rotation cylinder 1 and the fixed cylinder 3, respectively.

The apparatus shown in FIG. 1 rotates a rotary cylinder 1 by a motor (12, 13), and a magnetic tape (not shown) is helically wound around the outer circumferential surface 10 of the rotary cylinder 1 and the outer circumferential surface 11 of the fixed cylinder 3. ) with the head 2, and has a function of reading signals recorded on a magnetic tape.

When recording with the head 2, the track width of the magnetic tape is very narrow (usually on the order of several tens of micrometers) in order to achieve high-density recording.
is required to make the swing as small as possible. Experiments have shown that good recording and reproduction cannot be obtained unless the amount of wobbling is generally controlled to %10 μm or less.

In order to suppress whirling of the rotating part to a small extent, it is effective to have a sufficiently large bearing support force with respect to the weight of one rotating part and the unbalanced weight. Therefore, in the device shown in FIG.
16' is provided.

FIG. 2 shows the bearing housing 6 in detail. Each of the grooves forming the groove group 16 (or 16') opens vertically on the movement direction side (advancement side) with respect to the movement direction of the bearing housing 6 (direction of arrow X in the figure), and extends rearward. Two grooves 16A that gradually become narrower as the
, 16B, and a groove portion 16C parallel to the axis 4 direction that connects the narrowest portions of these two groove portions 16A and 16B.
It is made up of. A plurality of grooves constituted by 16A, 16B, and 16C are arranged in parallel in the movement direction X, in other words, in the circumferential direction of the inner peripheral surface of the housing 6, forming a groove group 16 (or 16').

When using a groove for generating dynamic pressure as shown in FIG. In the case of the example, air is used, but other gases or liquids such as lubricating oil may be used) to flow along the grooves 16A and 16B to generate dynamic pressure, and this flowing fluid is held by the groove 16C. be able to. That is, the groove group 16 includes inclined groove portions 16A and 16B.
It has a pressure increasing function of increasing the bearing support load by increasing the bearing support load, and a pressure accumulating function of holding the increased support load by the groove portion 16C, thereby realizing an increase in the support load. This "υ"-shaped groove realizes a higher allowable bearing support profile than the conventional V-groove. As a result, the whirling of the rotary cylinder 1 becomes extremely small, which plays a major role in achieving good recording and reproduction. Furthermore, when the groove shown in Figure 2 is used, the contact area between the shaft and the inner peripheral surface of the bearing housing is small, and the fluid retention performance is extremely high. There will be no problems caused by contact with.

In the embodiment shown in FIG. 1 and FIG.
Although the present invention is not limited to this, the present invention should not be limited to this.

Of course, a group of grooves for generating dynamic pressure may be formed on the shaft. In addition, in the above embodiment, the shaft is a stationary member and the bearing part is a rotating member, but the present invention is not limited to this, and the shaft may be a rotating member and the bearing part is a stationary member. Of course. Also, even when the shaft is a rotating member.

The grooves for generating dynamic pressure may be formed on either the shaft surface or the bearing surface, and these should be considered to be within the scope of the present invention.

Next, another embodiment of the present invention will be explained with reference to FIGS. 3 and 4. FIG. 3 shows the overall configuration of the embodiment device, and FIG. 4 shows a partially enlarged view of the shaft 4 in FIG. 3. In FIG. 3, the rotating cylinder 1 has the shaft 4 in its center. There is. Therefore, the shaft 4 undergoes a rotational movement together with the cylinder 1 for one revolution. The fixed cylinder 3 has a bearing housing 60 in its center, and the shaft 4 is inserted into a hole in the bearing housing 60 with a slight gap in which the shaft 4 can rotate. The head 2 is installed on a rotating cylinder via the helad base 9.1 The motor is composed of a rotor 12 and a stator 13.A magnetic tape (not shown) is helically wound around the outer peripheral surfaces 10 and 11. The recording and reproduction of signals by the head 2 is the same as in the embodiment shown in FIG. In addition, in FIG. 3, the non-contact type signal transmission section is omitted from the drawing.

The shaft 4 in FIG. 3 has groove groups 16 on the top and bottom for generating dynamic pressure.
0.160' is formed. That is, as shown in FIG. 4, the groove has two inclined groove parts 160A and 160B (
160A' and 160B'), and a pressure accumulating groove 160C that connects the narrowest part thereof.
(160G'), and a groove group is formed by arranging a plurality of these grooves in parallel at a roughly equal pitch in the direction of rotational movement X.

As the shaft 4 rotates due to the rotation of the rotary cylinder 1, the fluid supplied from the outside or existing between the shaft 4 and the inner peripheral surface of the bearing housing 60 is pumped into the pressure increasing grooves 160A and 160B of the dynamic pressure generating groove. , and this pressurized fluid is held by the pressure accumulating groove 160C.

Thereby, the whirling of the rotary cylinder 1 can be kept very small. The fluid used in this example is air, but other gases or liquids such as lubricating oil may also be used. However, when using liquids such as lubricating oil, in order to prevent liquid leakage, Consideration should be given to the following: as well as the creation of a passage for replenishing liquid from the outside to the bearing. Therefore, if lubricating oil is used, for example, the structure becomes somewhat complicated.

Next, using FIG. 3, we will compare the allowable bearing support load W between the groove-shaped hydrodynamic bearing device used in the embodiment of the present invention described above and the conventional hydrodynamic pressure bearing device using a V-groove. explain. In FIG. 3, the vertical axis is W, and the horizontal axis is the eccentricity Ex between the shaft and the bearing housing, which is the result of analyzing these relationships using the finite element method. The characteristics shown in Figure 3 are:
The comparison was made under the same conditions such as bearing size for each groove shape. Table 1 shows typical values of the parameters used in the calculations in FIG.

As is clear from Table 1 and Figure 3, as the eccentricity Ex increases, the allowable bearing support load W increases. The value of the supporting load W is always larger than that of a conventional bearing having a V-groove.

This is extremely useful in reducing the whirling of the rotating part as described above.

Figure 6 shows the connecting groove 16G with a length of 2Ω1) and the inclined groove 16.
The horizontal axis is the ratio to the maximum axial distance (2l2) between A and 16G (this ratio is referred to as the groove length ratio), and the bearing of the present invention is determined for the groove length ratio (Q 1 / Q 2). The value of the ratio of the allowable support load Wu by the V-groove shaft amount to the allowable support load Wv by the V-groove shaft amount (this ratio is referred to as the support load ratio) is shown on the vertical axis. When the supported load ratio Q1/Qz=O, it is a so-called V groove, and the supported load ratio Wυ/Wv at this time is 1.0.As can be seen from the diagram, the groove length ratio Qx/Ω is 0. .1
The supporting load ratio Wu/Wv increases rapidly from the vicinity of exceeding 10%), and (At/Qx=
It has an inflection point around 0.25. And a1/fl
When x=0.6, Wu/Wv becomes about 1.23,
When it reaches its maximum value, i.e. near fix/nz=o, 6, the allowable bearing support load Wυ reaches its maximum, and the groove shaft amount Wv
This is an increase of approximately 23% compared to the previous year. Moreover, when jlt/At becomes larger than about 0.81, the value of W u /W v becomes smaller than 1.1 and rapidly decreases.

This is considered to be because the effect of the inclined grooves 16A, 16B is reduced. From FIG. 6, by setting the value of the groove length ratio at/Qt to 0.25<Qt/at<0.81, it is possible to realize an increase in the allowable bearing support load W by at least 10%. Therefore, Ωh
The value of /Qx is preferably 0.25<Qz/Qt<0.81, and more preferably the value of as/n* is 0.3.
<jlz/fix<0.8, Luno is good, Ωx/Fi
If the value of m is selected from 0.4 to 0.7, it is expected that the allowable bearing support load will increase by about 20%.

Next, regarding the pressure accumulating groove 16C, the angle 2 at the center thereof is
The state of the supporting load ratio when θ is changed as shown in FIG. 7 is shown in FIG. 9 by solid line A. When θ=30°, the shape is the same as that of the V groove. As can be seen from Figure 9, θ=451
When this happens, an allowable bearing support load that is about 10% higher than that of a V-groove can be obtained. It can be seen that the allowable support load increases in proportion to the increase in θ until the angle θ becomes 90°, that is, until the groove portion 16C becomes parallel to the axial direction. From this result, it can be considered that the groove shapes for generating dynamic pressure in the embodiments shown in FIGS. 1 to 4 described above are the best. Further, as shown in FIG. 8, an experiment was conducted by changing the pressure accumulating groove 16C in two stages. In this case, the inclination angle O
The relationship between this and the supporting load ratio is shown by the curve shown by the broken line B in FIG.

In addition, as shown in FIG. 8, the angle at the intersection of the part parallel to the axial direction and the inclined part in the groove part 16G is -90°.
is defined as θ, and θ was increased along a straight line where the angle between the intersection point and the axis rotational movement direction was 15°. The dashed line B curve in FIG. 9 shows the results. As shown by broken NIAB in Figure 9, the allowable support load increases as θ increases, and θ=90°
(the shape in which the groove portion 16C is parallel to the axial direction) is the maximum. According to the broken line B, when θ=39@, the allowable bearing support load increases by about 10% compared to the V-groove shaft amount.

The shape of the groove for generating dynamic pressure in the present invention is as follows.

For example, as shown in FIG. 10 and FIG. 11, the two inclined groove portions 16A are not limited to those described above.

16B and the connecting groove 16C in the center may be somewhat rounded, or 16A.

Either 16B or 16G may be somewhat curved; providing such a roundness improves workability when forming a groove by machining, and also improves machining accuracy. The entire groove is semicircular or oval.

Even with other curved shapes, if the inclination angle of the groove increases toward the center, a higher allowable bearing support load can be obtained than in the case of the groove.

Above, we have mainly described the formation of the groove portion 16G, but next, we will discuss the two inclined groove portions 16A.

The change in allowable bearing support load depending on the inclination angle of 16B will be explained. FIG. 12 shows this relationship. In this figure, the horizontal axis represents the angle β with respect to the rotational movement direction of the inclined groove portion 16A or 16B, and the vertical axis represents the maximum support load of 1.
Support load when set to 0 (support load/maximum support load)
As can be seen from Figure 1 showing the inclination angle β, there is an optimum value for the inclination angle β, and if it is in the range of approximately 8” to 42°, it will be 90% or more of the maximum support load.

Regarding the groove for generating dynamic pressure, the inclined groove 16A.

The groove width of 16B and the groove width of the pressure accumulating groove part 16G may be the same or different, 16A or 16B.
The performance can be controlled by making a difference between the groove width of 16G and the groove width of 16G, thereby making it possible to optimize the device to which it is applied. Also.

The grooves may be formed by a method such as etching.
For example, portions other than those corresponding to the grooves may be built up by welding, vapor deposition, etc. to form grooves as a result.

Next, in the above-described embodiments, the case of a radial bearing was mainly explained, but the present invention can also be applied to a thrust bearing. For example, in a thrust bearing such as the one formed by the end surface 7 of the shaft 4 and the thrust bearing plate 5 in FIG. It is good to form it on plate 5,
In this case, a specific example of the groove shape provided for one rotational movement direction is shown in FIG. 13. In Figure 13, axis 4
An example is shown in which a groove 16 for generating dynamic pressure is provided on the end surface 7 of the cylinder. Each groove is composed of two inclined groove portions 16A and 16B for increasing pressure, and a groove portion 16G for accumulating pressure orthogonal to the rotation direction. Even in such thrust bearings, compared to conventional ■groove bearings.

The allowable bearing support load increases and stable support can be achieved.

In the above explanation, a groove is used as a means for generating dynamic pressure, but the present invention is not limited to this. As shown in FIG. In this case, the protrusion may be formed by any processing method.The protrusion is also composed of two inclined parts and a communication protrusion that connects them. Ru. As the member rotates once, the pressure of the fluid increases along the two inclined parts, and the pressure is maintained at the connecting protrusion. Therefore, in the case of the protrusion, the same effect as in the case of the groove can be achieved, and the same effect can be achieved.

〔Effect of the invention〕

As described in detail above, according to the present invention.

A bearing device with a large bearing support load and stable support can be realized.

[Brief explanation of drawings]

FIG. 1 and FIG. 2 are diagrams showing one embodiment of the present invention. 3 and 4 are views showing another embodiment of the present invention, and FIG.
9 to 9 are diagrams for explaining the performance of the bearing according to the present invention, and FIGS. 10 and 11 are diagrams showing other examples of the groove shape for generating dynamic pressure according to the present invention, FIG. 12 is a diagram showing changes in performance due to changes in the shape of the groove for generating dynamic pressure, and FIGS. 13 and 14 are diagrams showing other embodiments of the present invention. DESCRIPTION OF SYMBOLS 1... Rotating cylinder, 2... Head, 3... Fixed cylinder, 4... Shaft, 5... Thrust bearing plate, 6...
・・Bearing housing song, 7・・Shaft end face, 16, 16'
...Groove group for dynamic pressure generation, 16A, 16B, 16C--
・Groove, 16o. 160'...Groove group for dynamic pressure generation, 160A, 160B
.

Claims (1)

[Claims] 1. A groove for generating dynamic pressure is formed in at least one of a rotating member or a stationary member disposed opposite to the rotating member, and a surface facing the rotating member and the stationary member is formed. In a hydrodynamic bearing device that supports a rotating member by generating dynamic pressure by rotating the rotating member with a fluid interposed therebetween, the groove is arranged in a direction of relative movement between the rotating member and the stationary member. In contrast, it is composed of a pressure increasing groove that is open on the advancing side and becomes narrower toward the rear, and a pressure accumulating groove that connects the narrower part of the pressure increasing grooves. Features of dynamic pressure type fluid bearing device. 2. In the hydrodynamic bearing device according to claim 1, a plurality of grooves for generating dynamic pressure are formed in at least one of the rotating member or the stationary member in the direction of relative movement. , a hydrodynamic bearing device characterized in that the grooves are formed at substantially equal pitches. 3. In the hydrodynamic bearing device according to claim 1 or 2, the groove for generating dynamic pressure is formed in at least one of the rotating member or the stationary member at right angles to the relative movement direction. A hydrodynamic bearing device characterized in that a plurality of sets are formed in a direction in which the bearings are aligned. 4. The hydrodynamic bearing device according to claim 1, wherein the pressure accumulating groove is formed as a groove parallel to the rotation axis. 5. In the hydrodynamic bearing device according to claim 1, the ratio between the minimum pitch (2l_1) and the maximum pitch (2l_2) in the rotation axis direction between the pressure increasing grooves is 0.
A hydrodynamic bearing device characterized in that the pressure is between 3 and 0.8. 6. A hydrodynamic bearing device according to claim 1, wherein the fluid is a liquid. 7. A hydrodynamic bearing device according to claim 1, wherein the fluid is a gas. 8. Fitting the shaft member and the housing member, interposing a fluid between the facing surfaces of the shaft member and the receiving surface of the housing member, and at least either the shaft member or the receiving surface of the housing member. A groove for generating dynamic pressure is formed on one side.
In a hydrodynamic bearing device that supports a rotating member through relative rotational movement between the shaft member and the housing member, the groove for generating dynamic pressure is configured to control the relative rotation between the shaft member and the housing member. The relative rotation is carried out between two inclined groove parts which are open on the upstream side with respect to the direction of the fluid flow due to the movement and gradually narrows toward the downstream side, and a position where the two inclined grooves are at their narrowest parts. 1. A hydrodynamic bearing device comprising a groove communicating in a direction perpendicular to motion. 9. The hydrodynamic bearing device according to claim 8, characterized in that the shaft member is a member on the rotation side, and the groove for generating the dynamic pressure is formed on the surface of the shaft member. Dynamic pressure type hydrodynamic bearing device. 10. The hydrodynamic bearing device according to claim 8, wherein the shaft member is the rotating member, and the groove for generating dynamic pressure is formed on the receiving surface of the housing member. Dynamic pressure type hydrodynamic bearing device. 11. The hydrodynamic bearing device according to claim 8, characterized in that the housing member is a member on the rotating side, and the groove for generating the dynamic pressure is formed on the receiving surface of the housing member. Dynamic pressure type hydrodynamic bearing device. 12. The hydrodynamic bearing device according to claim 8, wherein the housing member is the rotating member, and the groove for generating the dynamic pressure is formed in the shaft member. Device. 13. In the hydrodynamic bearing device according to any one of claims 8 to 12, a plurality of the grooves for generating dynamic pressure are formed in the direction of the relative rotational movement, and A hydrodynamic bearing device characterized in that pitches between the two are substantially equal. 14. A hydrodynamic bearing device according to any one of claims 8 to 13, characterized in that a plurality of sets of the grooves for generating dynamic pressure are formed in the direction of the rotation axis. Hydrodynamic bearing device. 15. In the hydrodynamic bearing device according to claim 8, the ratio of the minimum value to the maximum value of the distance between the two inclined groove portions is between 0.3 and 0.8. A hydrodynamic bearing device characterized by: 16. The hydrodynamic bearing device according to claim 8, wherein the fluid is a gas. 17. The hydrodynamic bearing device according to claim 8, wherein the fluid is a liquid. 18. In the hydrodynamic bearing device according to claim 8, the groove for generating dynamic pressure is opposite to a surface of the longitudinal end of the shaft member or a surface of the longitudinal end of the shaft member. A hydrodynamic bearing device characterized in that the hydrodynamic bearing device is formed on a receiving surface of the housing member. 19. It has at least two opposing surfaces, these surfaces are arranged close to each other, a lubricating body is filled between these surfaces, and the lubricating body enters the gap between these surfaces due to relative movement of these surfaces, In a hydrodynamic bearing device that generates pressure and uses this pressure to support opposing surfaces that move relative to each other in a non-contact state, at least one of the opposing surfaces that move relative to each other is provided with a A series of grooves or protrusions are provided, which are open on the advancing side and closed on the rear side, and whose angle from the direction of relative motion increases toward the rear, and these are arranged in plural on the surface facing the relative motion. A hydrodynamic bearing device characterized by: 20. The hydrodynamic bearing device according to claim 19, wherein the series of grooves or protrusions are formed in a plurality at approximately equal intervals in the direction of relative movement. Hydrodynamic bearing device. 21. The hydrodynamic bearing device according to claim 19 or 20, characterized in that the series of grooves or protrusions are formed in a plurality of sets in a direction perpendicular to the direction of relative motion. Dynamic pressure type hydrodynamic bearing device. 22. The hydrodynamic bearing device according to claim 19, wherein a portion of the series of grooves or protrusions where the angle increases is orthogonal to the direction of relative motion. Dynamic pressure type hydrodynamic bearing device. 23. In the hydrodynamic bearing device according to claim 19, the length of the portion of the series of grooves or protrusions where the angle increases and the distance between the portions closest to the advancing side with respect to the direction of relative motion. The ratio is from 0.3 to 0.8
What is claimed is: 1. A dynamic pressure type fluid bearing device characterized by being between. 24. The hydrodynamic bearing device according to claim 19, wherein the lubricant is a liquid lubricant. 25. The hydrodynamic bearing device according to claim 19, wherein the lubricant is a gaseous lubricant. 26. In the hydrodynamic bearing device according to claim 19, the portion where the angle of the series of grooves or protrusions increases includes a linear or curved portion substantially perpendicular to the direction of relative motion. A hydrodynamic bearing device characterized by: 27. In a hydrodynamic bearing device having a rotating part and a fixed part supporting the rotating part, the rotating part with respect to the fixed part is inclined with respect to the rotation direction, and the upstream side with respect to the direction of fluid flow is Two inclined grooves or protrusions that are open and gradually narrow toward the downstream side are connected to a straight groove or protrusion perpendicular to the direction of rotation, and a plurality of these are arranged side by side on surfaces facing relative movement. What is claimed is: 1. A hydrodynamic bearing device comprising a bearing section. 28. A hydrodynamic bearing device according to claim 27, wherein the bearing portion is provided on a radial surface of the rotating portion. 29. The hydrodynamic bearing device according to claim 27, wherein the bearing portion is provided on a thrust surface of the rotating portion. 30. In the hydrodynamic bearing device according to claim 27, the ratio of the minimum value to the maximum value of the distance between the two inclined grooves or the protrusions is 0.3 to 0.8. A hydrodynamic bearing device characterized by: 31. A hydrodynamic bearing device according to claim 27, wherein the fluid is a liquid or gaseous lubricant. 32. A hydrodynamic bearing device having a rotating part having a magnetic head and a fixed part supporting the rotating part, and used in a device that performs magnetic recording and reproducing by winding a magnetic tape around the rotating part, wherein the rotating part Alternatively, a groove for generating dynamic pressure may be formed in the surface of the fixed part facing the rotating part, and a fluid may be interposed between the facing surfaces of the rotating part and the fixed part, so that the movement is caused by the rotation of the rotating part. generating pressure to support the rotating part;
The dynamic pressure generating groove includes two grooves that are open on the advancing side and narrow toward the rear with respect to the direction of relative movement between the rotating part and the fixed part due to the rotation of the rotating part; 1. A hydrodynamic bearing device comprising: a groove portion that communicates between narrowed portions of the groove portion.