JPH11132234A - Slide bearing for shaft - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the corresponding life of a bearing bush. SOLUTION: A fastening member 27, for making an annular collar 241 abut on a supporting shoulder in a frictional force securing state, is inserted between an abutting plate 32 and a bearing bush 24, and is fixedly fastened to a bearing shield 25 in a condition where an annular gap 29 to a shaft 16 remains.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sliding bearing for a shaft such as a rotor shaft or a rotor shaft of an electric motor, provided with a bearing shield, the bearing shield being made of sintered metal. The bearing bush is accommodated coaxially, and the bearing bush has an annular collar for being axially supported by a support shoulder formed on the bearing shield. The present invention relates to a type in which a contact plate is mounted.

[0002]

2. Description of the Related Art A rotor shaft or a rotor shaft of an electric motor is supported by a two-position bearing device based on the principle of a fixed / movable bearing in a motor casing. In this case, a sliding bearing made of sintered metal (sintered iron or bronze) is preferably used. Such a sliding bearing has a good sliding action by impregnating a large number of fine holes provided in the sliding bearing with oil.

[0003] Known sliding bearings of this kind ("Construktions Elemente der Feichmeichnik")
(Konstruktionselemente der Feinmechanik) Werner Krause, publisher Carl Hanser V
erlag, München, Vienna, 1989, 3rd
In the case of page 62), direct axial contact takes place in a bearing bush made of sintered metal. However,
Since the bearing bush made of sintered metal has only a low strength against impacts, there is not enough strength under vibration loading and the bearing bush wears relatively quickly.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to extend the service life of a bearing bush.

[0005]

In order to solve this problem, according to the structure of the present invention, the contact between the contact plate and the bearing bush is provided.
A tensioning member (Spannbrille) for frictionally coupling the annular collar to the supporting shoulder is inserted, and the tensioning member is fixedly secured to the bearing shield while leaving an annular gap to the shaft. I was there.

[0006]

The sliding bearing according to the present invention has a structure in which the bearing bush is structurally fixed to the bearing shield by a tension member fixed to the bearing shield.
The axial abutment is no longer performed directly on the bearing bush, but on the tensioning element. This avoids penetration of relatively soft sintered metal, that is, wear. At the same time, a kind of labyrinth seal is provided by the tensioning member. This labyrinth seal prevents the carbon dust generated by the abrasion of the brushes from penetrating into the sliding bearing when the electric motor is formed as a commutator motor or a collector motor, and thus prevents premature failure of the sliding bearing. . The tension member is
Absorb the axial force given by the contact plate directly,
This axial force is introduced into the bearing shield via the annular collar of the bearing bush and directly into the bearing shield. In this case, the force component guided via the annular collar is related to the inherent rigidity of the tension member.

When the sliding bearing is configured as the fixed bearing as described in claim 6, the axial force generated from the direction of the stopper is further guided to the tension plate via the bearing bush, and the bearing is transmitted via the tension plate. Introduced inside the shield. Since only a small component of such an axial force is guided via the annular collar, the transition between the cylindrical part of the bearing bush and the annular collar is based on the notch effect occurring at this location. The potential weak points of the bearing bush that exist are only slightly loaded.

[0008] The features set forth in the further claims enable advantageous further developments of the sliding bearing according to the first claim.

According to an advantageous embodiment of the invention, the width of the annular gap present between the shaft and the inner edge of the tensioning member is dimensioned as small as possible, ie, taking into account the manufacturing errors that occur. However, the dimensions are set so small that the shaft and the tension member do not come into contact with each other. Due to such a construction, the inherent rigidity of the tensioning member remains largely unaffected and the axial direction acting on the tensioning member, which must be bypassed to the bearing shield via the annular collar of the bearing bush. The force component remains relatively small.

According to an advantageous embodiment of the invention, the bearing bush is inserted into a stepped hole formed in the bearing shield. In this case, having a larger hole diameter,
The axial depth of the bore section containing the annular collar is slightly less than the axial height of the annular collar. Thus, when the tensioning member is fixed in position on the bearing shield, a preload force acting on the bearing bush is generated. This preload force ensures that the bearing bush is securely axially positioned within the bearing shield.

The fixed mounting of the equipped shaft in the sliding bearing in the axial direction is, according to an advantageous embodiment of the invention,
On the one hand, the contact plate is fixed to the shaft so that it cannot rotate,
On the other hand, on the opposite side of the bearing bush from the contact plate, a stopper is arranged so as to be axially immovable on the shaft, and the bearing bush is supported by the stopper via the second contact plate. Is realized by: The contact plate and stopper
The arrangement is such that the axial play in the fixed bearing is very small, preferably about 0.1 mm. By means of such axial play, on the one hand, unacceptably high axial frictional forces on the sliding bearings are avoided, on the other hand extremely high axial forces are generated due to vibration loads,
This axial force is transmitted directly to the tensioning element via the bearing bush, so that an unacceptably high load is not applied to the annular collar of the bearing bush.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention shown in the drawings will be described.

The electric motor, partially shown in longitudinal section in FIG. 1, is formed as a commutator motor and has a casing 10. This casing has a stator 1
1 is accommodated therein, and a rotor 12 rotating in the stator 11 is supported. The stator 11 supports an excitation pole 13 formed as a permanent magnet, while the rotor 12 receives a rotor winding 14. The rotor winding is fitted in a groove of the thin plate package, and the coil end of the rotor winding is connected to the commutator piece 151 of the collector or commutator 15. Collector 1
The current extraction from 5 is effected in a known manner by a spring-preloaded carbon brush 19.
These carbon brushes are radial in the casing 10
It is housed in a brush holder 20 fixedly secured therein.

The rotor shaft 16 is fixed to the casing 10 by a two-position bearing device based on the principle of fixed and movable bearings.
It is supported within. In FIG. 1, the left bearing of the rotor shaft 16 is a movable bearing 21, and the right bearing is a fixed bearing 22. Both bearings 21 and 22 are formed as sliding bearings with bearing bushes 23 and 24 made of sintered metal fixed in the casing. In this case, the movable bearing 21 is a cylindrical bearing, and the fixed bearing 22 is a color bearing.

The fixed bearing 22 is housed in a bearing shield 25. This bearing shield is a casing 10
Is fixedly fixed within. This bearing shield 25
Has a coaxial stepped hole 26. The bearing bush 24 having the annular collar 241 is accommodated in the stepped hole. The stepped hole 26 and the bearing bush 24
The axial depth of the larger diameter section 261 of the stepped hole that houses the annular collar 241 is
1 are slightly less than the axial height of each other (FIG. 5). Thereby, the bearing bush 24
Is an end face adjacent to the annular collar 241 and slightly protrudes beyond the bearing shield 25. Bearing shield 2
On such a side of 5, a tensioning member 27 is fixed. This tensioning member is formed by the annular collar 2 of the bearing bush 24.
The bearing bush 24 is fixed in the stepped hole 26 of the bearing shield 25 so as to be axially immovable.

The tension member 27 having a high inherent rigidity is shown in FIG.
3 and the cross-sectional view shown in FIG. The tensioning member 27 has a central hole 28 coaxial with the rotor shaft 16. The diameter of this hole leaves an annular gap 29 as small as possible between the rotor shaft 16 and the edge of the hole. Are selected such that they do not touch at any point (FIG. 1). The tensioning member 27 is a bearing bush 2
4 which completely covers the annular collar 241 and extends beyond this annular collar. In this overhanging region, the tensioning member 27 has a plurality of, in this embodiment a total of four, through holes 30. The tightening members 27 are fitted over the rivet projections 31 through these insertion holes. These rivet projections are stamped integrally on the end face of the bearing shield 25. The tension member 27 is fixed to the bearing shield 25 by centering and riveting the rivet projection 31. In this case, the tensioning member generates an axial crimping force on the bearing bush 24 by projecting the bearing bush 24 beyond the end face of the bearing shield 25 by the dimension a (FIG. 5). This crimping force causes the annular collar 241 of the bearing bush 24 to move the shoulder 26 of the stepped hole 26 between the two hole sections 261 and 262.
Tightly fixed at 3. The preload force (preload force) of the tension member 27 is set to be larger than the axial force generated by the vibration load on the rotor shaft 16.

To form the fixed bearing 22, a contact plate 32 is arranged on one side of the bearing shield 25, and a stopper is arranged on the other side of the bearing shield 25. The abutment plate 32 and the stopper are both connected to the rotor shaft 16 so as not to move in the axial direction and to rotate. The stopper is formed by a drive pinion in the form of a spur gear 33. Spur gear 33 and bearing bush 2
4, a second contact plate 34 is further mounted. This abutment plate may be loosely mounted on the rotor shaft 16 or non-rotatably connected to the rotor shaft. The contact shoulder of the spur gear 33 is the bearing bush 24
If the outer diameter of the second contact plate is larger than the outer diameter of the second contact plate, the second contact plate 34 may be omitted. When assembling the fixed bearing 22, first, the contact plate 32 is connected to the rotor shaft 16 by, for example, press connection or welding. Then, the spur gear 33 is fixed to the rotor shaft 16 again by press connection or welding. In this case, the fixed bearing 22 has a maximum of 0.3 mm.
The spur gear 33 is mounted so that there is an axial play of 1 mm, that is, the rotor shaft 16 can move axially by 0.1 mm relative to the bearing shield 25. Such axial play is necessary to avoid unacceptably high axial friction.

Such axial play produces, based on the vibration load, an axial force which is related to the magnitude of the play.
Such axial forces of such a magnitude that they cannot be absorbed without damage by the annular collar 241 of the bearing bush 24 are received by the tension members 27. An axial contact is made between the contact plate 32 and the tension member 27. The axial force from the direction of the contact plate 32 is directly absorbed by the tension member 27 and
Through the bearing shield 25. Contact plate 3
Due to the outer diameter of 2, only a smaller component of the axial force needs to be diverted to the annular collar 241. How high such a component is related to the inherent rigidity of the tension member 27. This rigidity is set relatively high. The axial force generated from the direction of the spur gear 33 is further guided directly to the tension member 27 via the bearing bush 24, and the tension member 27
Through the bearing shield 25. Due to the small size of the hole 28 in the tensioning member 27, the force is guided consistently without diverting and, consequently, a cut-off based on the bypass edge at the transition from the annular collar 241 to the cylindrical part of the bearing bush 24. It is ensured that the chipping effect is almost inconspicuous.

[Brief description of the drawings]

FIG. 1 is a partial longitudinal sectional view of an electric motor formed as a commutator motor.

FIG. 2 shows the bearing shield of the electric motor as indicated by arrow II in FIG.
It is a figure shown in the state seen by.

FIG. 3 shows the bearing shield of the electric motor as indicated by arrow II in FIG.
It is a figure shown in the state seen by I.

FIG. 4 is a sectional view taken along the line IV-IV in FIG. 2;

FIG. 5 is an enlarged view of a portion indicated by reference numeral v in FIG.

[Explanation of symbols]

Reference Signs List 10 casing, 11 stator, 12 rotor, 13 excitation pole, 14 rotor winding, 15 commutator, 16 rotor shaft, 19 carbon brush, 20 brush holder, 21 and 22 bearing,
23, 24 bearing bush, 25 bearing shield,
26 stepped holes, 27 tension members, 28 holes, 2
9 annular gap, 30 insertion hole, 31 rivet projection, 32, 34 contact plate, 33 spur gear (stopper), 151 commutator piece, 241 annular collar, 2
61,262 hole section, 263 shoulder

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Uwe Hammer German Mark Groningen Pappelweg 1

Claims (9)

[Claims] A sliding bearing for a shaft, such as a rotor shaft or a rotor shaft of an electric motor, provided with a bearing shield (25), said bearing shield (25).
A bearing bush (24) made of sintered metal is coaxially accommodated in the bearing shield (2).
5) has an annular collar (241) for being supported in the axial direction by the support shoulder (263) formed in the support shoulder (263).
2), the annular collar (241) is frictionally connected between the abutment plate (32) and the bearing bush (24) in a frictional manner.
A tensioning member (27) to be applied to 3) is inserted,
The tension member has an annular gap (2) with respect to the axis (16).
A sliding bearing for a shaft, characterized in that it is fixedly fastened to a bearing shield (25) while leaving 9). 2. The sliding bearing according to claim 1, wherein the width of the annular gap is made as small as possible. 3. A bearing bush (24) is inserted into a stepped hole (26) machined into a bearing shield (25) and accommodates an annular collar (241) with a larger hole diameter. 3. The sliding bearing according to claim 1, wherein the axial depth of the bore section (261) is slightly smaller than the axial height of the annular collar (241). 4. The tensioning member (27) includes a bearing shield (2).
5), the rivet projection (31) integrally stamped on the end face of the bearing shield (25) is immovably tightened, and the rivet projection is formed in the fastening member (27). 2. The projection of claim 1, wherein said projection projects through said hole.
The sliding bearing according to any one of claims 1 to 3. 5. The method according to claim 1, wherein a preload force applied to the bearing bush by the tensioning member is greater than an axial force generated due to a vibration load on the shaft. A sliding bearing according to any one of the preceding claims. 6. In order to form the bearing as a fixed bearing (22), the abutment plate (32) is fixed to the shaft (16) so as to be axially immovable, and the bearing bush (24)
On the end face opposite to the annular collar (241), a stopper (33) is arranged so as to be axially immovable on the shaft (16), and between the stopper (33) and the end face of the bearing bush (24). The second contact plate (34) is inserted, and the two contact plates (32, 34) and the stopper (33) are formed such that the axial play in the fixed bearing (22) is extremely small. The sliding bearing according to claim 1, wherein the sliding bearing is arranged on the sliding bearing. 7. The sliding bearing according to claim 6, wherein the first abutment plate (32) is connected to the shaft (16) by press-fitting or welding. 8. The stop according to claim 6, wherein the stop is formed by an end face of the drive pinion and is non-rotatably mounted on the shaft by press-fitting or welding.
The slide bearing as described. 9. The sliding bearing according to claim 1, wherein the tension member has a high intrinsic stiffness.