DE102011009554B4 - Writing instrument for dispensing a liquid medium - Google Patents

Abstract

Writing instrument for dispensing a liquid medium (17), comprising a housing shaft (11), a tank space (18) for the liquid medium (17) provided in the housing shaft (11), an applicator (14) for the liquid medium (17), an intermediate piece (16) which is arranged at a front end (12) of the housing shaft (11) between the applicator (14) and the tank space (18) and the supply of the liquid medium (17) to the applicator (14), a piston (21) arranged displaceably in the tank space (18) for filling the tank space (18) with liquid medium (17) by suction, and a compensating chamber (39) with variable extension which extends into the tank space (18) and an interior space (42), characterized in that the interior space (42) communicates with the ambient air (43) at least during writing.

Description

The present invention relates to a writing instrument for dispensing a liquid medium, comprising a housing shaft, a tank space for the liquid medium provided in the housing shaft, an applicator for the liquid medium, an intermediate piece, which at a front end of the housing shaft between the applicator and the tank space is arranged and the supply of the liquid medium to the applicator is used, a piston arranged displaceably in the tank space for filling the tank space with liquid medium by suction, and a variable expansion chamber, which extends into the tank space and having an interior space.

Such a writing instrument is from the US 2 403 039 A known.

Further, the present invention also relates to a tank unit for a writing instrument for dispensing a liquid medium, the writing instrument having a liquid medium applicator and an intermediate piece disposed at a front end of a housing shaft between the applicator and the tank unit, and a piercing pin for the connection of the tank unit and the supply of the liquid medium from the tank unit to the applicator, and wherein the tank unit provided in a pen-like housing tank space for the liquid medium, a connection for the piercing, and a piston arranged displaceably in the tank space for Filling the tank space with liquid medium by suction has.

Such a tank unit is from the DE 22 18 949 A known.

One from the DE 93 05 608 U1 Known writing instrument is a fountain pen with a rigid ink tank, which is connected via an air exchange membrane with a pressure compensation chamber, which is formed as a kind of balloon on the side remote from the ink tank side of the piston. The balloon is surrounded by a closed pressure control chamber in the piston, which communicates via throttle bores with the ambient air.

The ink tank is internally vented through ventilation ducts in the intermediate piece, so that the used ink is replaced by bubbling air. In the air space of the ink tank, a small negative pressure is maintained to allow air to bubble into the ink tank and in turn drain ink to the nib.

It is known that in such fountain pens or similar writing instruments with internally vented ink tank, changes in temperature or ambient air pressure can cause the air in the ink tank to expand and push ink out of the nib.

This can even lead to decreasing ambient air pressure, so for example in the airplane, or with increasing temperatures, for example by solar radiation or the body temperature at a worn in the shirt pocket writing instrument that ejects after removing the front cap ink from the fountain pen.

The DE 93 05 608 U1 tries to solve this problem by the pressure compensation chamber, which is in air exchange with the tank interior. The balloon is housed in another pressure control chamber to maintain in the ink tank the slight negative pressure relative to the environment can. If the air pressure inside the ink tank increases in relation to the environment, air flows through the membrane into the pressure compensation chamber, which causes the pressure in the ink tank to drop.

When retracting the piston into the ink tank of the fountain pen is usually held vertically, since he was previously immersed in an inkwell, from which he is to be filled. The air which has previously accumulated in the ink tank during the consumption of the ink is then above the remaining ink. This air can not escape, so that it is compressed and escapes due to the pressure through the membrane in the pressure compensation chamber. It also pushes ink from the ink tank forward into the inkwell.

When the piston is moved all the way forward, which the user recognizes by the resistance when actuating the piston mechanism, there is thus air under overpressure in the pressure equalization chamber, which can not escape because the tip of the fountain pen is now immersed in the inkwell. When moving back the piston, this air escapes only very gradually back into the ink tank because of the intermediate membrane and thus counteracts a complete filling. In addition, it is not ensured that an excess pressure does not occur in the air space remaining in the ink tank.

During repeated filling, more and more air accumulates in the system of ink tank and pressure equalization chamber because of the air exchange retarding membrane.

A reliable and durable function of the known fountain pen is thus not guaranteed.

From the prior art further approaches are known to prevent the unwanted escape of ink during pressure and / or temperature changes.

That's how it shows DE 30 11 419 A1 in the 3 a writing instrument with a rigid ink tank whose rear wall is flexible, so that it inverts when emptying the ink tank inside. The ink tank itself must not be ventilated inside so that no air can collect there, which could lead to unwanted escape of the ink in the event of pressure and / or temperature fluctuations.

The bubbling of air over the ink channel, which connects the ink tank with the nib, but can not be completely avoided. As a result, air still accumulates in the ink tank, so that pressure and / or temperature fluctuations nevertheless lead to unwanted escape of the ink.

Furthermore, the undisturbed discharge of the ink during writing is not ensured here,

To fill the ink tank, the flexible rear wall should be pulled up over a drawstring. This type of filling is not practical and not reliable.

The DE 321 278 A shows a writing instrument, in which the front cap when plugged onto an ink supply channel final valve acts such that when plugged cap, the valve is closed and opened again with the cap removed. If the cap is not attached, ink may leak due to pressure changes.

The DE 43 28 312 A1 shows a fountain pen with variable ink tank, which consists of a bellows, which contains the reservoir as the ink. The outside of the ink tank is ventilated, internal ventilation is not provided. Again, there are problems with the flow of ink when writing and reliable filling.

These systems have not prevailed because of the disadvantages described in the market.

In the from the US 2 403 039 A known writing device, the interior of the compensation chamber is connected only during the filling of the tank space with the ambient air. The compensation chamber is formed by a flexible hose in which the piston is mounted longitudinally displaceable. By retracting the piston, the compensation chamber contracts, with the space at the back of the piston now communicating with the ambient air. By contraction of the compensation chamber ink is sucked into the tank space by the writing tip.

After filling, the piston is in its forward position, in which the expansion chamber has its maximum extent. The compensation chamber is no longer connected to the ambient air, so that the known writing instrument has the disadvantages described above.

The from the above-mentioned DE 22 18 949 A known tank unit is designed for a writing instrument in the form of a piston converter. The known tank unit has no compensation chamber extending into the tank space.

Against this background, the present invention has the object, the above-mentioned writing instrument and the aforementioned tank unit to continue to form such that it is permanently reliable and easy to fill in space-saving design.

In the case of the above-mentioned writing instrument, this object is achieved according to the invention in that the interior communicates with the ambient air at least during writing.

In the aforementioned tank unit, this object is achieved in that the tank unit has a compensation chamber with variable extent, which extends into the tank space inside and the interior of which communicates at least when writing with the ambient air.

The object underlying the invention is thus completely solved in this way.

The advantage here is in particular that due to the combination of piston mechanism and vented compensation chamber outside a secure filling of the tank space is possible. The medium flowing out during writing is replaced by the compensation chamber which continues to expand or project into the tank space, so that reliable drainage of the liquid medium is ensured even without internal ventilation of the tank space.

If the tank space is to be refilled, the piston in the tank space is moved forward in the direction of the applicator in a manner known per se. The variable in their volume, ie their expansion compensation chamber is compressed between the intermediate piece and the piston.

The air in the interior of the compensation chamber escapes into the environment. Air, the accumulates because of a deliberately intended internal ventilation or inadvertently in the tank space is expressed by the intermediate piece. Air can not accumulate in the tank room.

When retracting the piston to fill the tank space by suction with new liquid medium, the compensation chamber is also not pushed back into the tank space, because in the interior of the compensation chamber there is no pressure because it is in communication with the environment. Even if the compensation chamber would be attracted by the suction of the medium again something in the tank space, while it gets air into the tank space.

In the event of fluctuations in the temperature or the ambient pressure, the compensation chamber now ensures that there is always a pressure inside the tank space that corresponds to the ambient pressure. If the tank room is not ventilated inside, pressure and / or temperature fluctuations anyway have little or no effect.

If, on the other hand, the tank space is internally ventilated, significantly less air collects there than in the case of known internally ventilated tank spaces because of the expansion chamber which expands variably into the tank space when the medium flows out. The lower air supernatant already causes pressure and / or temperature fluctuations to have only a slight effect. But even the change in volume of possibly accumulating in the tank space air does not lead to an unwanted outflow of the medium, but is compensated by a change in the expansion of the compensation chamber.

Changes in the pressure of the ambient air have a disadvantageous effect anyway only if there is also air inside the tank space. This can be present in the writing instrument according to the invention only if medium has already drained from the tank space and replaced by bubbling air. But this is also accompanied by an expansion of the compensation chamber into the tank space.

Pressure changes can now be compensated by a further expansion of the compensation chamber into the tank space than by a return or compression of the compensation chamber.

The new design also saves space, because the compensation chamber does not need to be provided with extra volume in the writing instrument as it can be completely located in the tank space.

It is preferred if the interior of the compensation chamber communicates via a valve arrangement with the ambient air.

Here it is advantageous that the expansion of the compensation chamber can be influenced by closing or opening the valve arrangement. If, for example, the valve assembly is closed during retraction of the piston, ie during the suction of medium, the previously compressed compensation chamber can not expand again into the tank space, which thus can be completely filled.

Furthermore, it is preferred if a transfer space is arranged between the interior of the compensation chamber and the ambient air.

This transfer space serves as a kind of intermediate storage, which is closer to the compensation chamber than the ambient air and thus allows an even faster exchange of air with the interior of the compensation chamber. The resulting in a change in volume of the compensation chamber in the interior of the overpressure or negative pressure is thus reduced immediately over the transfer room and then completely compensated through the connection of the transfer room to the ambient air.

This ensures safe drainage of the medium and quick compensation for pressure and / or temperature changes.

In general, it is preferred if the interior of the compensation chamber is sealed in a gastight manner with respect to the tank space.

The advantage here is that no air is exchanged between the tank space and the interior of the compensation chamber.

It is preferred if the compensation chamber arranged on the piston, preferably designed as a bellows, which is further preferably attached to the tank side of the piston.

These measures are constructive advantage. For example, a bellows has a defined shape with respect to a balloon so that it can expand and collapse in a defined manner. If the compensation chamber is seconded directly to the piston, then it can fill in its expansion almost the entire volume of the tank space, which can therefore be used almost completely for outflowing medium.

This arrangement is also particularly space-saving.

Further, it is preferred if the valve arrangement is arranged on the piston and is further preferably biased by a spring into its open position.

Here it is advantageous that the valve assembly is seated close to the compensation chamber, so that the interior space can be shut off without greater air gaps between the ambient air. Structurally, it is also advantageous that the valve arrangement is arranged where the appropriate space is available, because the piston must anyway fill the entire cross-sectional area of the tank space.

The spring ensures that the valve assembly is kept open at rest.

In general, it is preferred if the valve arrangement is designed such that it seals the interior of the compensation chamber when filling the tank space with respect to the ambient air, preferably seals the interior of the compensation chamber relative to the ambient air at a taking place for filling the tank space movement of the piston from the tank space out ,

In this case, it is further preferred if the valve arrangement is designed such that it connects the interior of the compensation chamber with the ambient air during a movement of the piston preceding the filling of the tank space into the tank space.

Here is in each case of advantage that the air balance between the interior of the compensation chamber and the environment is interrupted only when you feel.

Further, it is preferred if a piston mechanism is provided for displacing the piston in the tank space, and the valve arrangement is actuated via the piston mechanism.

This measure is structurally advantageous because the anyway provided piston mechanism also actuates the valve assembly at the same time.

For the valve assembly itself various constructions are conceivable, two concrete examples are described in more detail below. Alternatively, a control tube in the manner of a coaxial valve is conceivable, which is displaced via stops on the intermediate piece and in the rear rest position of the piston between the open and closed positions.

The new writing instrument may provide for ventilation of the tank space via the intermediate piece, although this is not required. Thus, the system of compensation chamber, piston and piston mechanism can also be used for piston converter. Piston converters are self-sufficient, refillable tank units. In the case of existing fountain pens, they are plugged onto the puncture pins provided on the intermediate piece instead of the ink cartridges designed as disposable items. These new piston converters are then universally applicable, regardless of whether the fountain pen provides ventilation of the tank space on the piercing or not.

The new tank unit can be manufactured as an independent intermediate and supplied to the manufacturers of writing instruments, which then build their own housing shops and other components with the tank unit.

The tank unit preferably has the features discussed above in connection with the writing instrument according to the invention.

The tank unit may be an installation unit permanently mounted in the writing instrument or a piston converter removably disposed in the writing instrument.

Preferably, the writing instrument is designed as a piston fountain pen, in which case the applicator is a nib and the liquid medium is writing ink or ink.

However, the invention can also be used with other writing instruments that are used for applying liquid media. In particular, ink pens, ballpoint pens or devices for applying correction agents or colors should be mentioned here.

Finally, it should be mentioned that in the context of the present invention "lower end" or "front end" means the area at the front tip of the writing instrument, where the applicator protrudes from the housing and the writing instrument is detected by the user.

Accordingly, "upper end" or "rear end" means the area of the writing instrument remote from the lower end.

Thus, "from below" means the direction pointing from the lower to the upper end and "from above" means the direction pointing from the upper to the lower end. "Above" or "below" meaning "towards the rear end toward" or "toward the front end toward".

Accordingly, "axial direction" means the longitudinal direction of the writing instrument of hers front to its rear end, so the direction of the longitudinal central axis.

"In connection with the ambient air" in the context of the present invention means that the space in question can deliver air to the environment or receive it.

Further advantages will become apparent from the description of the accompanying drawings.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

An embodiment of the invention is illustrated in the drawing and will be explained in more detail in the following description. Show it:

1 in a schematic side view of a longitudinal section through a known writing instrument, which is designed as a piston fountain pen;

2 a representation like 1 , wherein the known writing instrument is designed as a filling penholder with piston converter;

3 a very schematic and enlarged view of the piston fountain pen from 1 in its rearward area;

4 a schematic, enlarged and fragmentary view of the piston and compensation chamber, as in the Kolbenfüllfederhalter 3 and the piston converter off 2 are usable, with the valve assembly open;

5 a representation like 4 , but with closed valve assembly; and

6 in a presentation like 4 or 5 an alternative construction for the valve assembly 3 ,

In 1 is not to scale in a schematic longitudinal section and in side view a writing instrument 10 shown, which serves for discharging liquid media. The writing instrument 10 in 1 has a housing shaft in the usual way 11 has, on which the writing instrument 10 is detected by the user.

In the housing shaft 11 is at its front end 12 an applicator 14 , for example in the form of a quill pen 15 arranged. The applicator 14 stands with an intermediate piece 16 in operative connection, via the liquid medium 17 from a tank room 18 to the applicator 14 is directed.

In the tank room 18 is at its rear end in the longitudinal direction 19 of the writing instrument 10 slidably arranged piston 21 intended. The piston 21 is about a known per se piston mechanism 22 longitudinal 19 displaceable.

The housing shaft 11 is at its rear end 23 with a knob 24 provided, over which the piston mechanism 22 is pressed.

The writing instrument 10 can be used to apply any liquid media, for example, for applying paints or correction agents. The applicator 14 is then designed as a brush, wick or Kugelapplikator.

However, preferred is the design of the writing instrument 10 as a piston fountain pen 25 , In this case, it is the liquid medium 17 in the tank room 18 usual writing ink or ink.

The construction of the writing instrument 10 or the piston fountain pen 25 is known per se. To fill the tank room 18 with medium 17 becomes the piston 21 about the piston mechanics 22 in 1 to the left to the front end 12 of the housing shaft 11 hazards. Before or at least immediately afterwards becomes the pen 15 dipped in an inkwell and then over the knob 24 The piston 21 again 1 move to the right. At this movement of the piston 21 in the tank room 18 becomes medium 17 in the tank room 18 sucked into it.

While writing becomes medium 17 from the tank room 18 over the intermediate piece 16 to the applicator 14 directed. The media flow is via capillary channels and possibly ventilation channels in the intermediate piece 16 regulated, as is well known.

About the intermediate piece 16 Air bubbles penetrate into the tank room 18 one that replace the spent medium, leaving itself in the tank room 18 over time less and less medium and more and more air is.

When in the tank room 18 If a certain amount of air is now present, a change in temperature or pressure, for example when flying or when exposed to sunlight, causes the air in the tank space 18 expands. This can lead to medium 17 uncontrolled from the applicator 14 is delivered.

This problem with known writing instruments 10 as they are in 1 are shown at the new writing instrument 10 avoided in a structurally simple way.

With this new design, it is no longer necessary in the intermediate piece 16 Provide ventilation ducts, the invention also with existing writing instruments 10 cooperates, in which this "internal ventilation" of the tank room 18 over the intermediate piece 16 is provided.

While in 1 a writing instrument 10 according to the principle of operation of a piston fountain pen 25 shown shows 2 in a presentation like 1 a writing instrument 10 ' suitable for use with cartridges or so-called piston converters 26 is trained. For this purpose is at the intermediate piece 16 a piercing pin 27 trained, on which the cartridge or the piston converter 26 with her connection 27 ' be plugged.

The housing shaft 11 indicates at its rear end 23 now a cap 28 on, in a known manner the writing instrument 10 ' Close up or back.

The piston converter 26 is with its own pen-like housing 29 provided, in which in a manner known per se, a tank space and a piston and a piston mechanism are, as in connection with 1 have already been described and for reasons of clarity in 2 not shown. The operation of this piston mechanism via a at the rear end of the piston converter 26 provided knurled nut 31 that are not radially beyond the contour of the pen-like housing 29 protrudes and thus completely inside the housing shaft 11 to come to rest.

The piston converter 26 is thus an independent tank unit 32 for filling with liquid medium from the housing shaft 11 is taken out.

To the piston converter 26 to fill with ink, he will be at its front end with the connector 27 ' dipped in an inkwell and then over the knurled nut 31 the previously pushed forward piston in the tank space 18 withdrawn. So far corresponds to the function of the piston converter 26 in the writing instrument 10 out 1 installed tank unit 32 However, there as a built-in unit 33 is trained.

Under a mounting unit 33 is in the context of the present invention, a tank unit 32 understood that permanently in a writing instrument 10 is installed. The installation unit 33 supplies the tank space 18 , the piston 21 as well as the piston mechanics 22 while applicator 14 , Intermediate piece 16 , Housing shaft 11 and knob 24 depending on the quality and design of the writing instrument 10 can be designed differently.

The constructive improvement of such known writing instruments 10 . 10 ' , Piston converter 26 or installation units 33 now concerns each of the pistons 21 as well as the tank room 18 ,

In connection with the 3 This innovation is now on the hand of a piston fountain pen 25 described in 3 is shown in a very schematic, greatly enlarged representation and only in its rückwertigen range.

Left in 3 is partially still the intermediate piece 16 to recognize in which an ink capillary 34 is hinted at the tank room 18 with the in 3 not shown nib 15 combines.

The piston 21 is with a spindle 35 connected with external thread, which is in a sleeve 36 screwed with internal thread. The sleeve 36 is rotatable with the knob 24 connected.

Between the spindle 35 and the sleeve 36 So it's a thread 37 provided so that when turning the sleeve 36 the spindle 35 in 3 is moved to the left or right. So that the sleeve 36 not from the housing shaft 11 pushes out, this is rotatable but axially immovable stored in a suitable and known manner.

In this way form spindle 35 and sleeve 36 a spindle screw, as is commonly used in piston mechanisms of Kolbenfüllfederhaltern or piston converters.

By turning the knob 24 in one or the other direction can thus the piston 21 in the tank room 18 be moved to the tank room 18 with liquid medium 17 So here with writing ink to fill.

This is the piston 21 first in 3 driven all the way to the left, and then moved back to the right after immersing the writing tip in an inkwell. While writing, the piston is located 21 in its very right position, giving the volume of the tank space 18 is immutable.

On the piston 21 is on his tank side wall 38 now a compensation chamber 39 in the form of one of segments 40 constructed bellows 41 intended. The segments 40 are in a known manner for bellows against each other in the longitudinal direction 19 movable. The bellows 41 consists of a material that matches the particular medium 17 is compatible, so even after many years of contact not is attacked. Furthermore, the material is flexible enough that the segments 40 can be compressed and expanded.

The bellows 41 can be different distances in the tank space 18 extend into it, which by its dashed outline at 41 ' is indicated.

In this way, the bellows can 41 almost the whole inner volume of the tank room 18 fill in, if it is extended accordingly far. In the schematic representation of 3 was omitted for reasons of clarity, the bellows 41 to show in its full radial extent.

The bellows 41 serves as a compensation chamber with variable expansion to the consumption of liquid medium 17 compensate, leaving in the tank room 18 no air accumulates when the medium 17 is gradually consumed.

This is made possible by the bellows 41 on the one hand gas-tight against the tank space 18 is complete and on the other hand about its interior 42 communicates with the ambient air in 3 between the piston 21 and the sleeve 36 through a gap 43 is indicated.

This gap 43 communicates via different, design-related and / or deliberately provided openings with the environment of the fountain pen 25 so in the gap 43 the ambient air at the same pressure and temperature as the ambient air outside the fountain pen 25 is.

In the flask 21 is also at 44 indicated valve assembly provided, which is the interior 42 with the ambient air in the gap 43 combines.

In still to be described manner, the valve assembly 44 always open when the piston 21 himself in his in 3 shown, located at the rear, or when he is from the rest position of the 3 out in the tank room 18 is driven to the left to the piston 21 into the position, out of the tank space 18 can be filled by sucking up with new ink.

As long as the valve assembly 44 open, the bellows will be 41 at outflow of medium 17 from the tank room 18 further into the tank room 18 expand into so the loss of medium 17 compensate.

In the event that due to pressure or temperature change, the volume of the medium 17 in the tank room 18 enlarged, or that air in the tank room 18 into it, which expands significantly when the temperature changes, this overpressure is absorbed by the compensation chamber 39 reduced, the bellows 41 So from the tank room 18 withdraws.

That way, in the tank room 18 no overpressure arise, so the piston fountain pen 25 even with strong changes in the ambient air or in the temperature does not unintentionally emit or spray ink.

Because the ventilation of the interior 42 of the bellows 41 even with the movement of the piston 21 in 3 is maintained to the left, the bellows 41 completely collapsed, keeping it close to the tank side wall 38 of the piston 21 is present, if this in 3 was driven to the left.

Now the valve assembly 44 closed, so no additional ambient air in the interior 42 can arrive when the piston 21 for absorbing medium 17 in the tank room 18 into 3 is driven back to the right.

When the piston 21 has reached its rear rest position again, opens the valve assembly 44 again, so now at the outflow of medium 17 from the tank room 18 the bellows 41 back to the tank room 18 can expand into it.

It should be noted that the bellows is formed such that the interior 22 gas-tight against the tank space 18 is complete, so no air from the interior 42 in the tank room 18 or in the opposite direction. Of course, this gas-tight separation also means that no medium 17 in the interior 42 can get.

It should also be mentioned that the valve assembly 44 via an air duct 45 with the interior 42 and over air ducts 46 with the gap 43 is in air exchange.

Finally, in 3 to realize that the piston 21 radially outside with seals 47 is attached to the inner wall 48 the tank room 18 lie so tightly that between the space 43 and the tank room 18 neither air nor medium 17 can be exchanged.

In 4 is now shown on the basis of a concrete embodiment, as the valve assembly 44 is trained and controlled.

4 shows in an enlarged, fragmentary illustration of the piston 21 from the 1 to 3 as well as the left of the piston 21 subsequent bellows 41 , the part here in the tank room 18 is extended.

It can be seen that the piston 21 an outer bulb 48 as well as an inner piston 49 which is in the outer bulb 48 slidably arranged.

The inner piston 49 points inside the outer bulb 48 lying a head 51 on, on which a compression spring 52 rests against an annular extension 53 of the outer bulb 48 supported.

In this way, the inner piston 49 over the compression spring 52 forward into the outer bulb 48 pushed.

The inner piston 49 is at his in 4 right end with the spindle 35 the usual piston mechanism connected in 4 for the sake of clarity is not shown.

In the inner bulb 49 is a transfer room 54 provided, in which a pin 55 protrudes, on the tank side wall 38 of the outer bulb 48 is provided.

In the cone 55 it runs out 3 known air duct 45 that the interior 42 of the bellows 41 connects with the ambient air.

At his in 4 right end is at the pin 55 a thickening 56 with a sloping sealing surface 57 intended. In a corresponding way, the gap 54 at his in 4 left end a radially inward-facing projection 58 on, on which a sloping sealing surface 59 is provided.

In 4 is the valve assembly formed in this way 44 shown in their open position, in which they by the compression spring 52 is biased.

The interior 42 communicates via the air duct 45 , the transfer room 54 , one around the thickening 56 around forming annulus 61 , the space between the two sealing surfaces 57 and 59 , one between the pin 55 and the lead 58 forming annulus 62 and a gap 63 between the head 51 of the inner piston 49 as well as the tank side wall 38 of the outer bulb 49 with the room 64 in which the compression spring 52 is arranged.

The space 64 communicates about drilling 65 in the annular extension 53 with the gap 43 ,

In this way, there is an undisturbed exchange of air between the interior 42 as well as the gap 43 as long as the two sealing surfaces 57 and 59 are not in contact with each other.

The between the interior 42 as well as the gap 43 provided transfer room 54 serves to buffer short-term pressure peaks.

If now the piston 21 from the in 4 moved position shown to the left, this is done by the fact that the spindle 35 Pressure on the inner piston 49 is exercised, with her ring shoulder 66 in contact with the annular extension 53 of the outer bulb 48 arrives.

This way is via the spindle 35 the outer bulb 48 in 4 move to the left, without the valve assembly 44 is closed.

When the piston 21 now is driven to the left, so it is the bellows 41 squeezed as it is in 5 is shown. When compressing the bellows 41 the air escapes from its interior 42 over the connection described in the space 43 ,

If now to fill the tank room 18 The piston 21 in 5 is pulled to the right, then the inner piston 49 against the force of the compression spring 52 in the outer bulb 48 proceed until the two sealing surfaces 57 and 59 get in touch with each other. In the further process of the piston 21 in 5 to the right takes the inner piston 49 then the outer bulb 48 With.

Because the air connection between the interior 42 and the gap 43 now by the juxtaposition of the two sealing surfaces 57 . 59 closed, no air in the interior 42 arrive so that the bellows 41 in the compressed position together with the piston 21 is moved to the right. In this way arises in the tank room 18 a negative pressure caused by liquid medium 17 is filled when the tip of the writing instrument 10 or the piston fountain pen 25 immersed in an inkwell.

Once enough medium in the tank room 18 sucked in, the pulling movement over the spindle 35 to be ended. Then the outer bulb pushes 48 under the force of the compression spring 52 in 5 on the inner piston 49 so far to the right until the ring shoulder 66 again at the annular extension 53 is present and the position of 4 is achieved again, reducing the ventilation of the interior 42 is guaranteed again.

Due to the described functions so the interior 42 when filling the tank room 18 sealed against the ambient air. When ancestor of the piston 21 or in its rest position, however, is the interior 42 permanently in the air exchange with the gap 43 and therefore with the ambient air.

In 6 is in a comparable representation as 5 fragmentary and purely schematic of the piston 21 represented, in which now another variant of the valve assembly 44 is trained.

In the flask 21 is a longitudinal direction 19 extending through-hole 67 provided, in the longitudinally displaceable a control tube 68 is arranged.

The head tube 68 has a tank-side, disc-shaped head 69 and at the other end a disk-shaped head 71 on.

The length of the head tube 68 longitudinal 19 is one in 72 indicated amount greater than the length of the piston 21 and thus the through hole 67 longitudinal 19 , In this way, the head tube can be 68 in the piston 21 between the two stops that move through the heads 69 . 71 be formed.

In the head 69 is an air duct 73 provided, extending from the interior 42 of the bellows 41 into the interior of the head tube 68 extends and there radially outward in an opening 74 empties. This opening 74 is a transfer room 75 in the piston 21 assigned. From the transfer room 75 extends another air duct 76 to the gap 43 and thus is in communication with the ambient air.

The head 71 is with the spindle 35 connected, so that by a movement of the spindle in the direction of the longitudinal direction 19 the head tube 68 either with his head 69 or his head 71 in contact with the piston 21 is brought.

Between the piston 21 and the head 71 is still one in a blind hole 77 provided tension spring 78 provided the head 71 in contact with the piston 21 draws.

When the piston 71 in contact with the piston 21 is, the opening gets 74 in the area of the transfer room 75 so that the interior 42 now in exchange of air with the gap 43 stands. This is the valve position when the piston is at rest 21 , or then, if over the spindle 35 The piston 21 in the tank room 18 is moved in to then absorb the medium.

Will the piston 21 over the spindle 35 from the tank room 18 withdrawn, the head arrives 69 in contact with the piston 21 , which causes the opening 74 from the area of the transfer room 75 moved out and the air connection between the interior 42 and the gap 43 is interrupted.

As soon as the piston 21 is at rest, pulls the tension spring 78 the piston 21 back to the head 71 close and the valve assembly 44 opens again.

Merely for the sake of good order, it should be mentioned that the constructions are shown schematically in the figures. On the representation of the items, for example, the outer bulb 48 and the inner bulb 49 was omitted for reasons of clarity. The way in which these items are mounted and connected together is not the subject of the present application. Individual parts can for example be screwed, glued or clamped.

Claims (17)

Writing instrument for dispensing a liquid medium ( 17 ), with a housing shaft ( 11 ), one in the housing shaft ( 11 ) provided tank space ( 18 ) for the liquid medium ( 17 ), an applicator ( 14 ) for the liquid medium ( 17 ), an intermediate piece ( 16 ) at a front end ( 12 ) of the housing shaft ( 11 ) between the applicator ( 14 ) and the tank room ( 18 ) and the supply of the liquid medium ( 17 ) to the applicator ( 14 ), one slidable in the tank space ( 18 ) arranged piston ( 21 ) for filling the tank space ( 18 ) with liquid medium ( 17 ) by suction, and a compensation chamber ( 39 ) of variable extent, which is located in the tank space ( 18 ) and an interior space ( 42 ), characterized in that the interior ( 42 ) at least when writing with the ambient air ( 43 ). Writing implement according to claim 1, characterized in that the interior ( 42 ) of the compensation chamber ( 39 ) via a valve arrangement ( 44 ) with the ambient air ( 43 ). Writing implement according to claim 1 or 2, characterized in that a transfer room ( 54 ) between the interior ( 42 ) of the compensation chamber ( 39 ) and the ambient air ( 43 ) is arranged. Writing implement according to one of claims 1 to 3, characterized in that the interior ( 42 ) of the compensation chamber ( 39 ) opposite the tank room ( 18 ) is gas-tight. Writing implement according to one of claims 1 to 4, characterized in that the compensation chamber ( 39 ) on the piston ( 21 ) is arranged. Writing implement according to claim 5, characterized in that the compensation chamber ( 39 ) as a bellows ( 41 ) is formed, preferably the tank side ( 38 ) on the piston ( 21 ) is attached. Writing implement according to one of claims 2 to 6, characterized in that the valve arrangement ( 44 ) on the piston ( 21 ) is arranged. Writing implement according to one of claims 2 to 7, characterized in that the valve arrangement ( 44 ) via a spring ( 52 . 78 ) is biased in its open position. Writing implement according to one of claims 2 to 8, characterized in that the valve arrangement ( 44 ) is formed such that it the interior ( 42 ) of the compensation chamber ( 39 ) when filling the tank space ( 18 ) relative to the ambient air ( 43 ) seals. Writing implement according to claim 9, characterized in that the valve arrangement ( 44 ) is designed such that it is at a for filling the tank space ( 18 ) movement of the piston ( 21 ) from the tank room ( 18 ) out the interior ( 42 ) of the compensation chamber ( 39 ) relative to the ambient air ( 43 ) seals. Writing implement according to one of claims 2 to 10, characterized in that the valve arrangement ( 44 ) is designed such that it is at a filling of the tank space ( 18 ) preceding movement of the piston ( 21 ) into the tank room ( 18 ) into the interior ( 42 ) of the compensation chamber ( 39 ) with the ambient air ( 43 ) connects. Writing implement according to one of claims 1 to 11, characterized in that a piston mechanism ( 22 ) for moving the piston ( 21 ) in the tank room ( 18 ) is provided, and the valve assembly ( 44 ) via the piston mechanism ( 22 ) is pressed. Writing implement according to one of claims 1 to 12, characterized in that the writing instrument ( 10 . 10 ' ) as piston fountain pen ( 25 ), the applicator ( 14 ) a pen ( 15 ), and the liquid medium ( 17 ) Writing Ink ( 20 ) or ink is. Tank unit for a writing instrument ( 10 . 10 ' ) for dispensing a liquid medium ( 17 ), the writing instrument ( 10 . 10 ' ) an applicator ( 14 ) for the liquid medium ( 17 ) and an intermediate piece ( 16 ), which at a front end ( 12 ) of a housing shaft ( 11 ) between the applicator ( 16 ) and the tank unit ( 32 ) is arranged, and a tapping ( 27 ) for connecting the tank unit ( 32 ) and the supply of the liquid medium ( 17 ) from the tank unit ( 32 ) to the applicator ( 14 ), and wherein the tank unit ( 32 ) one in a pen-like housing (( 29 ) provided tank space ( 18 ) for the liquid medium ( 17 ), a connection ( 27 ' ) for the tapping ( 27 ), and one displaceable in the tank space ( 18 ) arranged piston ( 21 ) for filling the tank space ( 18 ) with liquid medium ( 17 ) by suction, characterized in that the tank unit ( 32 ) a compensation chamber ( 39 ) has a variable extent extending into the tank space ( 18 ) and its interior ( 42 ) at least when writing with the ambient air ( 43 ). Tank unit according to claim 14 having the features of one of claims 2 to 13. Tank unit according to claim 14 or 15, comprising a mounting unit ( 33 ) that is permanently in the writing instrument ( 10 ) is mounted. Tank unit according to claim 14, or 15, which is a piston converter ( 26 ) which is removable in the writing instrument ( 10 ' ) is arranged.

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