JPH0312037Y2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to a rotor of a magnet generator, and in particular,
The present invention relates to an improvement in the fixing structure of permanent magnets, and relates to one that is effective for use in the rotor of a magnet generator mounted on a small or special vehicle such as a motorcycle or a buggy.

[Conventional technology]

Generally, small or special vehicles such as motorcycles and buggies sometimes use magnet generators that utilize permanent magnets (hereinafter referred to as magnets) such as ferrite magnets.

This type of magnet generator consists of a rotor consisting of a plurality of magnets arranged and fixed at equal intervals around the inner periphery of a yoke, and a core with coils wound around multiple radial locations. The rotor is driven by the engine and rotates around the generator, thereby inducing an electromotive force in each magnetic pole coil of the generator.

Conventionally, as a rotor used in such a magnet generator, a resin case is formed by connecting a plurality of magnet storage chambers of a shape corresponding to the magnets in a ring shape with an open upper frame, which is fitted into a yoke. In some cases, a plurality of magnets are placed at intervals around the inner circumference of the yoke by inserting them into each housing chamber of the case (for example, see Utility Model Application No. 59-78877). .

In the rotor of such a magnet generator, the magnets are clamped and fixed by partition walls formed in adjacent housing chambers.

It is also conceivable to supplement the mechanical clamping of the magnet in the storage chamber by bonding the magnet to the yoke using an adhesive.

[The problem that the idea aims to solve]

However, when the rotor of such a magnet generator is used in an air-cooled engine that drives a vehicle such as a buggy where the vehicle speed does not increase even at high rotation speeds, the temperature of the oil inside the generator and the inside of the generator may become extremely high. The inventor of the present invention has revealed that there is a problem in that the resin case melts and the strength of the adhesive deteriorates, resulting in a decrease in the fixing force to the magnet.

If the fixing force to the magnet decreases, not only will the magnet move inside the yoke when angular acceleration from the engine is applied, resulting in a decrease in power generation function, but in the worst case, the magnet will crack and the generator will fail. It may scatter into the room and cause unexpected situations such as engine lock-up.

The present invention was developed with a focus on these problems, and its purpose is to provide a rotor for a magnet generator that can maintain a high fixing force to the magnet even under high temperatures. It's about doing.

[Means for Solving the Problems] The rotor of the magnet generator according to the present invention includes a yoke 11 that is formed in a bowl shape and has a winding margin 19 formed at its upper end, and a rotor that is fitted into the yoke 11. A partition wall portion 35 is provided on the top surface of the ring 33 formed in a circular ring shape.
A plurality of partition walls 3 are arranged at intervals in the circumferential direction and protrude at right angles, and the adjacent partition walls 3
A magnet storage chamber 31 is formed between each of the magnets 5 and 35, and has a case 13 integrally formed of a non-magnetic metal material, a height H that is less than the depth of the yoke 11, and a width W. It is integrally molded into a rectangular parallelepiped having an arc shape along the inner circumference of the yoke 11 in the direction, and each inclined part 22, 22 is formed on at least a part of both side surfaces located at both ends of the arc, and the yoke 11 has inclined parts 22, 22 extending outward in the circumferential direction. They are each formed so as to approach the circular arc-shaped outward surface 21 as they go, and are inserted into each of the magnet storage chambers 31, respectively, and both ends in the circumferential direction at the tip of each of the partition walls 35 are pressed by a press mold. Plastically deformed portion 4 that is plastically deformed in the circumferential direction
2 and 42 are pressed by the inclined parts 22 and 22, respectively, and a component force F directed outward in the radial direction is applied to the yoke 11 between the adjacent partition parts 35 and 35. A plurality of magnets 1 are each pressed and fixed to the inner peripheral surface.
2, a cylindrical cover 14 which is press-fitted into the inner circumferential surface of the group of magnets 12 in a state in which it is in close contact with the inner circumferential surface of each magnet 12, and is integrally molded from a non-magnetic metal material; The holding ring 15 is in contact with an upper flange 39 of the cover 14 disposed on the upper end surfaces of the case 13 and the magnet 12 group, and is integrally formed of a non-magnetic metal material. The staking margin 19 of the yoke 11 is radially inwardly rolled and crimped and pressed onto the presser ring 15.

[Effect]

According to the above-described means, the magnet 12 is pressed in the circumferential direction by the plastically deformed portion 42 of the partition wall 35 while being housed in the housing chamber 31 of the case 13 made of a non-magnetic metal material, and is also tilted. Since it is strongly fixed to the yoke 11 by being pressed outward in the radial direction at the portion 42, there is no risk of melting or a decrease in the fixing force. Therefore, unforeseen situations such as a decline in the functionality of the magnet generator due to the magnet 12 drifting due to melting or a decrease in fixing force, or the magnet 12 flying off, can be avoided.

Moreover, the magnet 12 is located in the housing chamber 3 of the case 13.
1, the magnet is pressed against the inner periphery of the yoke 11 and is strongly fixed, and is covered by the cover 14, so that the magnet moves freely due to the inertial force applied by angular acceleration during use. There is no rattling.

Furthermore, since the magnet 12 is surrounded all around by the case 13 and the cover 14 when it is fixed by the yoke 11, even if the magnet is damaged, fragments will not be scattered.

〔Example〕

Fig. 1 is an exploded perspective view showing a rotor of a magnet generator which is an embodiment of the present invention, Fig. 2 is a vertical sectional view showing its assembled state, Figs. 6
7, 8, 9, and 10 are longitudinal sectional views, enlarged partial perspective views, and partially omitted partially cutaway plan views showing the assembly in progress.

In this embodiment, the rotor as a magnetic unit includes a yoke 11 and a plurality of magnets 12.
, a case 13 , a cover 14 , and a holding ring 15 .

The yoke 11 is integrally molded with a magnetic material into a substantially bowl-like shape with an open upper surface and a closed lower surface, and the lower closed wall has a shaft hole 16 in the center for inserting a boss (not shown) that is directly connected to the engine. A plurality of attachment holes 17 for connecting the rotor to the boss are respectively formed at positions outside the shaft hole 16. The case 13 is located outside the mounting hole 17.
A plurality of protrusions 18 for preventing rotation are provided by pushing up the lower closing wall from the outer surface, and the mounting holes 17 and the protrusions 18 are arranged at arbitrary angles in the circumferential direction. A winding margin 19 is formed at the upper end of the yoke 11 by cutting the outer periphery.

The magnet 12 has a height H that is less than the depth of the yoke 11, and is integrally formed into a substantially rectangular parallelepiped having a circular arc shape curved along the inner circumference of the yoke 11 in the width direction. At both ends of the arc-shaped inward surface (hereinafter referred to as the ventral surface) 20 of the magnet 12, inclined portions 22 approach the arc-shaped outward surface (hereinafter referred to as the back surface) 21 as the magnet 12 goes outward in the circumferential direction. The inclined portions 22, 22 at both ends form a fan shape that becomes narrower on the inner diameter side. Rising side surfaces 23 and 23 on both sides where the inclined parts 22 and 22 are adjacent to each other, and an upper surface 24
and the lower surface 25 are formed parallel to each other.

The case 13 is integrally molded by die-casting or the like using a non-magnetic metal material such as aluminum, and has a generally cylindrical shape that fits inside the yoke 11 as a whole. A plurality of storage chambers 31 are formed in the cylindrical wall 30 of the case 13 and arranged in the circumferential direction with substantially equal phase differences. The housing chamber 31 is formed into a hollow chamber having a height h that is less than the height H of the magnet 12 and a width w that is slightly larger than the width W of the magnet 12. Each section is open to the public. Therefore, the case 13 has a shape in which a plurality of frames each having an open top are connected in a ring shape.

The floor walls 32 of each storage chamber 31, i.e. the horizontal pieces of each open upper frame, are adjacent to each other to form a series of rings 33, and the outer edges of the floor walls 32 of each storage chamber 31 are An adhesive receiving portion 34 for receiving adhesive is recessed to form an arc-shaped recess.

Between the adjacent storage chambers 31, 31, there are partition walls 35 corresponding to the vertical pieces of the upper open frame.
are formed to stand up in a columnar shape, and the wall thickness t of each partition wall portion 35 is formed to be slightly thinner than the wall thickness T of the magnet 12.

A plurality of recesses 36 are arranged and recessed in the lower surface of the ring 33 so as to be located directly below the partition wall 35 between the storage chambers 31 and 31, and each recess 36 corresponds to the projection 18 of the yoke 11. shaped to fit together.

The concave portion 36 and the convex portion 18 are formed in a relationship as shown in FIGS. 4 and 5, respectively. That is, the width A of the recess 36 is larger than the width a of the projection 18, and the width A of the recess 36 is larger than the width a of the projection 18.
The depth B of each of the convex portions 18 is set larger than the height b of the convex portion 18. Further, a relatively large radiused portion R is formed at the corner of the recessed portion 36, and a corner portion of the convex portion 18 is formed to have an edge portion E that is as sharp as possible.

The cover 14 is integrally formed by drawing press processing using a magnetic metal material such as a thin iron plate, and has a generally cylindrical shape that fits inside the case 13 as a whole. Before assembly, at the lower end of the cylindrical portion 37 of the cover 14, a lower flange 38 has a circular annular shape that protrudes radially inward, and at its upper end, an upper flange 39 protrudes radially outward. They are each formed in the shape of a circular ring.

The holding ring 15 is integrally formed by punching and pressing using a non-magnetic metal material, and is formed into a substantially annular shape having a notch 41 in a portion.

Next, the structure of the rotor of the magnet generator will be explained by explaining the assembly work of the rotor of the magnet generator using each component according to the above structure.

First, the case 13 is fitted into the yoke 11, and each convex part 18 raised on the bottom wall of the yoke 11 is fitted into each concave part 36 on the lower surface of the case 13, respectively. By fitting the convex portion 18 and the concave portion 36, the case 13 is prevented from rotating integrally with the yoke 11.

At this time, even if a plurality of recesses 36 and a plurality of protrusions 18 are provided, the tolerances are compounded and the positions of the recesses 36 and the depth B are different from each other, even if they are misaligned with each other. and height b are set to A>a, B>a, and this dimensional margin absorbs the positional deviation, so each convex portion 18
can be easily and reliably fitted into each recess 36.

However, with only such dimensional relationship, the recess 36
Since there is a margin in the fitting between the yoke 11 and the convex portion 18, the connection between the yoke 11 and the case 13 may be loose (slopping).
will occur.

However, in this embodiment, as shown in FIG.
When the edge E of the yoke 11 and the case bite into each other, a part of the convex part 18 becomes embedded in a part of the concave part 36, so regardless of the dimensional margin between the concave part 36 and the convex part 18, the yoke 11 and case 13 will be combined without any wobbling.

After or before fitting the case 13 into the yoke 11, as shown in FIG.
Adhesive 43 is supplied and stored in the adhesive receiving portion 34 formed at the bottom of each storage chamber 31 of the case 13. As the adhesive 43, it is preferable to use an adhesive that forms a paste with an appropriate viscosity while it is stored, and that hardens after being fluidized by heating, such as an epoxy resin. Possible materials include thermosetting adhesives.

Subsequently, the magnets 12 are inserted into each housing chamber 31 of the case 13 from above. At this time, since the width w of the storage chamber 31 is formed to be slightly larger than the width W of the magnet 12, each magnet 12 can be easily inserted into each storage chamber 31.

When the magnet 12 is inserted into the storage chamber 31 to the bottom, the adhesive 43 collected in the adhesive receiving portion 34 has a suitable viscosity, so that the magnet 12 is inserted into the storage chamber 31 as shown in FIG. At the same time, the magnet 12 is crushed by the lower surface of the yoke 11 and the storage chamber 31, and is pushed up into the narrow gap between the joint surfaces of the magnet 12, the yoke 11, and the housing chamber 31 due to capillary action.

After the magnets 12 are inserted into all the storage chambers 31 until they come into contact with the adhesive receiving parts 34 on the floor wall part 32, as shown in FIGS. A pair of concave plastic deformation parts 42, 42 are respectively arranged at substantially central positions on both end sides in the circumferential direction, and are simultaneously applied to each partition part 35 using a pressing die (not shown) such as a wedge-shaped punch. Or individually engraved.

With the depression formation of the concave plastic deformation parts 42, 42, the wall at the upper end of the partition wall part 35 expands and plastically deforms outward in the circumferential direction, so that the partition wall parts 35, 35 on both sides of the magnet 12 By pressing the magnet 12 inserted therein from both sides, it is strongly fixed.

At this time, a portion of the plastically deformed portion 42 engages and presses the inclined portion 22 on the side surface 23 of the magnet 12, so that the magnet 12 has a radially outward portion as shown in FIG. A force F will act on it. Due to this radially outward force F, the magnet 12 is strongly pressed and fixed to the inner peripheral surface of the yoke 11.

Thereafter, a cylindrical shape having an outer diameter approximately equal to the diameter of the circular inner circumferential surface of the 12 groups of magnets is formed inside the 12 groups of magnets which are housed and fixed in each housing chamber 31 of the case 13 and arranged in an annular shape. The cover 14 shown in FIG. 10 is press-fitted as shown in FIG. As a result, the outer peripheral surface of the cover 14 comes into close contact with the abdominal surface 20 of each magnet 12, but the wall thickness t of the partition wall 31 of the case 13 is formed to be slightly thinner than the wall thickness T of the magnet 12. Therefore, the outer circumferential surface of the cover 14 does not come into close contact with the abdominal surface of each partition wall 31.

During press-fitting, the flanges 38 and 39 are formed at the lower and upper ends of the cover 14, so even if the cover 14 is made of a thin iron plate, sufficient rigidity is ensured in the cylindrical portion 37. ing. Therefore, the cover 14 can be press-fitted into the case 11 smoothly, and the cylindrical portion 3 of the cover 14 can be press-fitted smoothly.
This is done so that the outer circumferential surface of the case 7 is in close contact with the inner circumferential surface of the case 14 uniformly throughout.

Further, since a jig for applying a pushing force or a reaction force opposing this to the cover 14 can be engaged with both the flanges 38 and 39 during press fitting, the press force is applied to the entire cover 14. This enables uniform biasing and more precise press-fitting.

Note that the lower flange portion 38 is then extended downward, and the cover 14 is formed into a cylindrical shape.

Thereafter, the presser ring 15 is applied to the upper flange 39 of the cover 14 that covers the upper end surface of the case 11, and the staking process is performed to press the staking margin 19 inward at the top end of the yoke 11. administered. As a result, the yoke 11, the magnet 12, the case 13, the cover 14, and the holding ring 15 are caulked and integrated.

The assembly is then heated by suitable heating means such as a furnace or the like. At this time, the assembly is placed so that the adhesive receiving portion 34 is above the magnet 12, that is, the yoke 11 is placed upside down.

The viscosity of the adhesive 43 decreases due to heating, making it extremely easy to flow. Therefore, the adhesive 43 in the adhesive receiving portion 34 located on the magnet 12 is applied by gravity to the gap between the magnet 12, the yoke 11, and the housing chamber 31. It also penetrates quickly and uniformly by capillary action. At this time, since the bottom surface of the yoke 11 faces upward, the fluidized adhesive 43 does not flow into the shaft hole 16 or the attachment hole 17. Further, the adhesive 43 that has flowed down to the terminal end of the magnet 12 is accommodated in the space formed by the cover 14, the holding ring 15, and the crimping margin 19, so that it does not flow out to the outside.

As the heating progresses, the adhesive 43 once fluidized
is now cured, so that the magnet 12 is adhered to the yoke 11 and the housing chamber 31 by the cured adhesive layer 44. At this time, since the adhesive layer 44 is uniformly spread over the joint surfaces of the magnet 12, yoke 11, and housing chamber 31,
Its adhesive strength is extremely high.

In this way, the rotor of the magnet generator shown in FIG. 2 was manufactured, and the magnets 12 were arranged at predetermined intervals on the inner circumference of the yoke 11 and were firmly fixed. It is becoming a state.

That is, in this rotor, each magnet 12 is fitted into the yoke 11 and the uneven portions 36, 18
The plastically deformed portion 42 is accommodated and positioned in each housing chamber 31 in the case 13 which is prevented from rotating by the
The yoke 11 is pressed against the inner circumferential surface of the yoke 11 by being compressed in the circumferential direction by the yoke 11 and is pressed against the inner circumferential surface of the yoke 11 by receiving a component force directed outward in the radial direction from the inclined portion 22 on the side surface. The magnet 12, the yoke 11, and the housing chamber 31 are bonded and fixed by an adhesive layer 44 formed by the adhesive 43 of the portion 34 penetrating between the magnet 12, the yoke 11, and the housing chamber 31 and hardening.

According to this embodiment, an inclined part is provided on the side surface of the magnet so that the inner diameter side becomes narrower, and a plastically deformed part is formed in the partition between the storage chambers so as to press against this inclined part. Since the plastic deformation portion cooperates with the structure to apply a force to the magnet in the direction of pressing it against the inner periphery of the yoke, the magnet can be strongly fixed to the yoke.

By the way, in a magnet generator connected to an air-cooled engine, etc., if the temperature of the oil inside the generator becomes abnormally high and a severe heat shock is applied to the rotor of the magnet generator, the resin may be used to fix the magnet to the yoke. If used, the resin may melt or its strength may decrease. In such a case, there is a risk that the magnet may float inside the yoke, reducing the functionality of the magnet generator, or the magnet may crack and scatter into the generator chamber, causing an unexpected situation such as the engine locking up. be.

However, in this embodiment, the magnet is pressed in the circumferential direction by the plastically deformed part of the partition while being housed in the housing chamber of the case made of non-magnetic metal material, and is also pressed in the radial direction at the inclined part. Since it is strongly fixed to the yoke by being pressed outward, there is no risk of melting or a decrease in the fixing force.

Therefore, unforeseen situations such as a decline in the functionality of the magnet generator due to magnet drift caused by melting or a decrease in fixing force, and magnets being scattered can be avoided.

A magnet is inserted into each accommodation chamber formed in the case, and a concave plastic deformation part is stamped on the partition wall of the case to pinch the magnet from both sides and hold it by pressing it against the inner peripheral surface of the yoke. Because of this structure, the number of parts and assembly man-hours can be reduced, and workability can be improved by eliminating the need for screws or rivets.Since each magnet is independent,
There are no unnecessary parts such as neutral parts,
Economically advantageous.

The magnet is compressed in the housing chamber of the case, is strongly fixed by being pressed against the inner periphery of the yoke, and is closely covered by the cover, so it is free from inertia caused by angular acceleration during use. The magnet does not move (rattle) due to force, and wear, deterioration, and destruction of various parts due to the movement can be suppressed.

When fixed with the yoke, the magnet is surrounded all around by the case and cover, so
Even if the magnet is damaged, the pieces will not fly away, and it is possible to prevent the occurrence of secondary failures due to flying pieces as the rotor rotates.

In the process of fitting the case into the yoke, even if multiple concave portions and convex portions are arranged, and the tolerances are compounded to cause misalignment with each other, the width and depth of the concave portion are It is set larger than the height, and this dimensional margin absorbs the positional deviation, so that the work of fitting each convex part into each concave part can be carried out easily and reliably.

In this way, it is possible to absorb dimensional tolerances and errors and fit the concave and convex portions, making it easy to automate the work of fitting the case into the yoke.

Furthermore, by forming a radius at the corner of the recess and an edge at the corner of the convex part, the edge of the convex part bites into the round part of the concave part, so that a part of the convex part becomes a part of the concave part. Since the yoke and the case are configured so as to be implanted in the yoke, the yoke and the case can be connected without rattling regardless of the dimensional margin between the recess and the protrusion.

Since the magnet is bonded to the yoke and the housing chamber by an adhesive layer that is penetrated and hardened from the adhesive receiver, the case can assist in mechanically fixing the magnet to the yoke. , the fixation of the magnet can be further ensured.

Fitting the case into the yoke, supplying adhesive to the adhesive receiver, inserting the magnet into the housing chamber of the case,
Driving the plastically deformed part into the partition wall, fitting the cover into the inner circumferential surface of the magnet group, and setting the retainer ring are all tasks performed from a single direction, making it extremely easy to work and fully automated. .

It should be noted that the present invention is not limited to the above-mentioned embodiments, and may be modified without departing from the gist thereof.
It goes without saying that various changes are possible.

For example, the inclined portion is not limited to being formed on a part of the side surface of the magnet, but may be formed by sloping the entire side surface into a fan shape.

Since the magnet is pressed against the inner circumferential surface of the yoke and strongly fixed by the cooperative action of the plastically deformed part and the inclined part, fixing with adhesive may be omitted.

The case is not limited to being formed by aluminum die-casting, but may also be formed by forging, sintering, etc. using aluminum or other non-magnetic metal materials.

The anti-rotation structure between the yoke and the case is not limited to a structure in which a convex part raised on the yoke fits into a recessed part recessed in the case. It may also be a structure in which provided protrusions are fitted into each other.

[Effect of idea]

As explained above, according to the present invention, the following effects can be obtained.

The magnet 12 is housed in the housing chamber 31 of the case 13 made of a non-magnetic metal material, and is pressed in the circumferential direction by the plastically deformed part 42 of the partition wall part 35, and is also pushed outward in the radial direction at the inclined part 22. Since it is strongly fixed to the yoke 11 by being pressed against it, there is no risk of melting or a decrease in the fixing force.

Therefore, unforeseen situations such as a decline in the functionality of the magnet generator due to the magnet 12 drifting due to melting or a decrease in fixing force, or the magnet 12 flying off, can be avoided.

The magnet 12 is compressed in the accommodation chamber 31 of the case 13 and is pressed against the inner periphery of the yoke 11 to be strongly fixed.
Because it is coated with
2 does not move (rattle), and wear, deterioration, destruction, etc. of various parts due to the movement can be suppressed.

When the magnet 12 is fixed in the yoke 11, the entire circumference of the magnet 12 is surrounded by the case 13 and the cover 14, so even if the magnet 12 is damaged, the fragments will not be scattered and the magnet 12 will not be damaged as the rotor rotates. It is possible to prevent secondary damage caused by flying debris.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view showing a rotor of a magnet generator which is an embodiment of the present invention, Fig. 2 is a vertical sectional view showing its assembled state, Figs. 6
7, 8, 9, and 10 are longitudinal cross-sectional views, enlarged partial perspective views, and partially omitted partially cutaway plan views showing the assembly in progress. 11...Yoke, 12...Magnet, 13...
... Case, 14 ... Cover, 15 ... Holding ring, 16 ... Shaft hole, 17 ... Mounting hole, 18 ...
...Convex portion, 19...Winning margin, 30...Cylinder wall,
31... Accommodation chamber, 32... Bottom wall, 34... Adhesive receiver, 35... Partition wall, 36... Recess, 37
...Cylindrical portion, 38...Lower flange, 39...Upper flange, 41...Notch, 42...Concave plastic deformation portion, 43...Adhesive, 44...Adhesive layer.

Claims (1)

[Claims for Utility Model Registration] A yoke 11 formed into a bowl shape and having a winding margin 19 formed at its upper end, and a ring 33 fitted into the yoke 11 and formed into a circular ring shape. Partition wall part 35 on the top surface of
A plurality of partition walls 3 are arranged at intervals in the circumferential direction and protrude at right angles, and the adjacent partition walls 3
A magnet storage chamber 31 is formed between each of the magnets 5 and 35, and has a case 13 integrally formed of a non-magnetic metal material, a height H that is less than the depth of the yoke 11, and a width W. It is integrally molded into a rectangular parallelepiped having an arc shape along the inner circumference of the yoke 11 in the direction, and each inclined part 22, 22 is formed on at least a part of both side surfaces located at both ends of the arc, and the yoke 11 has inclined parts 22, 22 extending outward in the circumferential direction. They are each formed so as to approach the circular arc-shaped outward surface 21 as they go, and are inserted into each of the magnet storage chambers 31, respectively, and both ends in the circumferential direction at the tip of each of the partition walls 35 are pressed by a press mold. Plastically deformed portion 4 that is plastically deformed in the circumferential direction
2 and 42 are pressed by the inclined parts 22 and 22, respectively, and a component force F directed outward in the radial direction is applied to the yoke 11 between the adjacent partition parts 35 and 35. A plurality of magnets 1 are each pressed and fixed to the inner peripheral surface.
2, a cylindrical cover 14 which is press-fitted into the inner circumferential surface of the group of magnets 12 in a state in which it is in close contact with the inner circumferential surface of each magnet 12, and is integrally molded from a non-magnetic metal material; The holding ring 15 is in contact with an upper flange 39 of the cover 14 disposed on the upper end surfaces of the case 13 and the magnet 12 group, and is integrally formed of a non-magnetic metal material. A rotor for a magnet generator, characterized in that the staking margin 19 of the yoke 11 is swaged inward in the radial direction and is pressed onto a presser ring 15.