Pneumatic piston and method for producing said pneumatic piston

Abstract

A pneumatic piston (100) for an electropneumatic modulator is disclosed. The modulator comprises a piston housing (20) having a chamber (25) for receiving the pneumatic piston (100). The pneumatic piston (100) comprises: a sealing element (110) for sealing an intermediate space between the pneumatic piston (100) and the piston housing (20); a piston body (120) having a recess (125) for receiving the sealing element (110); and a locking element (130), which is designed to fix the sealing element (110) in the recess (125) in a form-fitting manner.

Description

Technical Field

[0001] The invention relates to a pneumatic piston, an electro-pneumatic modulator and a method for manufacturing a pneumatic piston of an electro-pneumatic modulator. Background Art

[0002] For example, electropneumatic modulators are used in pneumatic brake systems for commercial vehicles in order to set the air pressure by means of targeted electrical actuation of valves in order to thus provide a desired brake pressure for the pneumatic brake.

[0003] For example, DE 10 2018 121 716 A1 discloses a conventional electro-pneumatic modulator and a pneumatic piston, wherein the piston has a hollow cylindrical shape and can move axially in a chamber of a piston housing. For example, the pressure in the chamber is gradually increased or reduced by a solenoid valve, which causes an axial movement of the piston. The seal between the piston and the housing is provided via a sealing ring, which is held below a cover plate. Here, the cover plate is welded to the piston body or held by hot caulking.

[0004] However, this fastening is disadvantageous because, in particular at the stop of the piston, strong acceleration forces act which can lead to the welded connection breaking and thus no longer reliably ensure the sealing of the piston in the piston housing.

[0005] Therefore, there is a need for an alternative pneumatic piston which ensures a more reliable sealing of the piston relative to the piston housing and withstands higher stresses over the long term. Summary of the invention

[0006] At least some of the above problems are solved by a pneumatic piston according to claim 1, an electropneumatic modulator according to claim 7 and a production method according to claim 8. The dependent claims define further advantageous embodiments of the subject matter of the independent claim.

[0007] The present invention relates to a pneumatic piston for an electronic pneumatic modulator. The modulator comprises a piston housing having a chamber for receiving a pneumatic piston. The pneumatic piston comprises a sealing element, a piston body and a locking element, wherein the sealing element is used to seal an intermediate space between the pneumatic piston and the piston housing, the piston body having a recess for receiving the sealing element, and the locking element is configured to fix the sealing element in the recess in a form-locking manner. It should be understood that the sealing element is configured to seal the intermediate space between the piston body and the housing only after the pneumatic piston is inserted into the piston housing.

[0008] Optionally, the pneumatic piston comprises a locking element which is designed to lock the securing element to the piston body. The locking element is not necessary, since the securing element can also be self-locking. In particular, the locking comprises an axial direction (direction of linear movement of the piston), wherein a movement or bending in a radial direction is possible or is only prevented after insertion into the housing.

[0009] Optionally, the locking element comprises at least one of the following: a groove, at least one undercut, at least one hook-shaped projection. The locking element can be an integral component of the piston body and does not have to be a separate element. For example, the groove can have a geometry such that the locking element can be introduced into the groove and retain the locking element in the axial direction.

[0010] Optionally, the locking element includes one of the following:

[0011] a locking ring, in particular a clamping ring, which can be snapped into the groove,

[0012] - two half-rings which can be locked by means of a groove and / or by means of at least one undercut and / or by means of at least one hook-shaped projection,

[0013] a toothed or non-toothed corrugated washer having a diameter selected such that the corrugated washer locks into the piston body when inserted,

[0014] at least one projection which can be pushed into at least one undercut and / or at least one hook-shaped projection (in order to be held there),

[0015] - At least one cutout, into which a projection on the piston body can engage in radial direction in order to prevent a relative rotation between the securing element and the piston body.

[0016] The locking element only needs to be held by a form-fitting connection. According to an embodiment, the locking element is not held by a hot caulking or welding connection. That is, the connection is releasable. However, the locking element can also be held by a frog-like clicker or frog effect (English: clicker). In this case, the locking element is self-locking because it is directly locked into the piston body (for example in an annular recess) by bending.

[0017] Optionally, the following materials may be used: the sealing element comprises rubber or plastic, the piston body comprises plastic or metal, and the locking element comprises plastic or metal.

[0018] Optionally, the piston body has the shape of a hollow cylinder or a cylinder. The sealing element and the locking element can be formed on the radially inner surface and / or on the radially outer surface.

[0019] Embodiments also relate to an electro-pneumatic modulator for a (pneumatic) brake system of a commercial vehicle. The modulator comprises: a pneumatic piston as described previously and a piston housing having a chamber for receiving the pneumatic piston.

[0020] Embodiments also relate to a method of manufacturing a pneumatic piston, wherein the method comprises the following:

[0021] - forming a piston body having a recess for receiving a sealing element;

[0022] - inserting a sealing element into the recess of the piston body in order to seal the intermediate space between the pneumatic piston and the piston housing; and

[0023] - The sealing element is locked in the recess by means of the locking element.

[0024] It will be appreciated that the recess and sealing element may be annularly formed.

[0025] Optionally, the step of forming the piston body is carried out by means of a folded core.

[0026] The exemplary embodiment overcomes the disadvantages of conventional pneumatic pistons by not requiring a welded connection and hot caulking between the piston body and the locking element. Instead, a material-locked connection is provided which also meets higher requirements over the long term. In this case, a large sealing ring can be supported directly on the cheek in the piston. Thus, a more robust material is available, without requiring welded parts for this purpose. Since no welding process is required, the exemplary embodiment offers the advantage that it can be manufactured more cost-effectively and more quickly and at the same time offers higher reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Embodiments of the present invention will be better understood from the following detailed description of different embodiments and the accompanying drawings, which, however, should not be understood to limit the disclosure to specific implementation forms but are merely for explanation and understanding.

[0028] Figure 1 A pneumatic piston according to one embodiment of the present invention is shown.

[0029] Figure 2 Another embodiment for a pneumatic piston is shown.

[0030] Figure 3 Shown can be used as Figure 2 A possible configuration of the locking element of the gasket in.

[0031] Figure 4A , 4BThe securing element is shown in a plan view and in a cross-sectional view and can be designed as a toothed corrugated washer according to a further embodiment.

[0032] Figure 5 A schematic flow chart of a method for producing a pneumatic piston is shown.

[0033] Figure 6 The use of a folding core during the manufacture of a pneumatic piston is shown. DETAILED DESCRIPTION

[0034] Figure 1 An embodiment of a pneumatic piston 100 is shown, which is inserted into the chamber 25 of the piston housing 20. The pneumatic piston 100 is exemplarily formed as a hollow cylinder, so that the inner through-opening of the pneumatic piston 100 surrounds the journal 22 of the piston housing 20 and adjoins the (cylindrical) outer wall 21. The seal between the piston body 120 and the journal 22 is provided by an annular sealing element 110, which is held on the piston body 120 by means of a securing element 130.

[0035] According to an embodiment, the securing element 130 is designed to hold the sealing element 110 in a positively locked manner in the axial direction in a recess 125 (e.g., an annular depression) of the piston body 120. At least after the pneumatic piston 100 has been inserted into the chamber 25, radial movement is no longer possible because the journal 22 or the piston body 120 prevents movement.

[0036] The securing element 130 can be fixed to the piston body 120 by means of a locking element 140, wherein there are various possibilities for this. Figure 1 In the embodiment, the locking element 140 is designed as a groove 142 in the piston body 120, into which the locking element 130 can be inserted. The fixing can be carried out before the pneumatic piston 100 is inserted into the chamber 25, because generally, after the insertion, the locking element 130 can no longer be released (or only when the pneumatic piston 100 is at least partially destroyed). In other words, for release, the locking element 130 needs to be radially compressed, which is prevented by the centrally arranged housing journal 22.

[0037] The sealing element 110 can be configured as an O-ring (e.g., made of rubber material) for sealing the connection between the piston body 120 and the housing 20, wherein the recess 125 for the O-ring 110 can be configured as a chamber portion. The locking element 130 holds the O-ring 110 in the chamber portion 125, for example, by means of a so-called circlip (locking ring or clamping ring), which engages in the groove 142 of the piston body 120 and is thus firmly fixed to the piston body 120. Therefore, the sealing element 110 cannot move in the axial direction (stroke direction of the piston).

[0038] In such Figure 1 In the assembled state shown, the securing element 130 cannot be lost, since compression of the securing ring 130 is prevented by the inner journal 22 of the housing.

[0039] According to further embodiments, it is also possible to fix a further sealing element 127 between the outer wall 22 and the piston body 120. Figure 1 In the embodiment of the present invention, the optional, additional sealing element 127 is arranged in an additional recess. Here, the additional sealing element 127 can also be realized via an additional locking element (not shown), which in turn establishes a positive connection with the piston body 120. Release can then only be achieved by disassembly, specifically for the same reasons as described for the inner locking ring 130.

[0040] However, the pneumatic piston 100 does not necessarily have to be in the shape of a hollow cylinder, but can also be formed as a conventional cylinder. Then, the housing journal 22 is missing. In this case, the sealing element 127 and the locking element are only present on the cylinder outer wall, but can be constructed there in the same way as in the described cylinder inner wall of the hollow cylinder shown.

[0041] For example, the locking ring 130 may include a plastic material or a metal. The piston body 120 may also include a plastic material, and the sealing element 110 may include a rubber material.

[0042] Figure 2 Another embodiment for a pneumatic piston is shown, in which the locking element 130 is a washer which lies perpendicularly to the axial direction on a shoulder section of the piston body 120. The washer 130 can be moved radially or laterally and is fixed by a locking element 140. The locking element 140 is designed as an undercut 144, behind which the washer 130 (locking element) engages and is thus held in its axial position perpendicular to the drawing plane.

[0043] After the pneumatic piston 100 has been inserted into the piston housing 20, the washer 130 can no longer be pushed out because the inner housing journal 22 (see Figure 1 ) prevents radial movement of the locking element 130. The washer 130 is thus again securely held in the undercut 144. The washer 130 is also not able to rotate (around the axial axis) because the projection 145 of the piston body 120 engages in the cutout of the washer 130 and holds the washer 130 in a rotationally fixed manner.

[0044] Figure 3 Shown in Figure 2 A possible configuration of the locking element 130 shown as a gasket in FIG. The gasket 130 is annularly configured and has a radially outward projection 133 and a radial cutout 135. Figure 2 The locking element 140 in the slot 135 can engage in the projection and the slot. As a result, the securing element 130 is again held in all spatial directions. The engagement of the locking element 140 in the slot 135 prevents (via the undercut 144) the projection 133 from being twisted and encircled, and prevents axial movement. Again, the central journal 22 (see Figure 1 ) prevents radial movement, the central journal engages in the central opening of the washer 130 with only a small amount of play.

[0045] According to a further embodiment, the locking element 130 is formed by two half rings (not shown in the figures), which can be engaged, for example, to the piston body 120 at the Figure 1 The two half rings are again designed to be so thick in the radial direction that the housing journal 22 can be fitted centrally with only a small amount of play and the half rings can then no longer be removed from the groove 142 (or can only be removed after the piston 100 has been removed from the housing).

[0046] Figure 4A A top view of another embodiment is shown, in which the locking element 130 is designed as a toothed corrugated gasket, which can be inserted into the annular recess 123 of the piston body 120. The outer diameter of the corrugated gasket 130 is slightly larger than the inner diameter of the annular recess 123. This makes it possible to press the corrugated gasket 130 into the annular recess 123 by means of a so-called frog effect or as a frog clicker. The outer teeth of the corrugated gasket 130 are locked into the piston body 120 and provide a stable hold for the sealing element 110 located below it by bending in this metastable state.

[0047] Figure 4B The cross-sectional view along the axial direction of the sealing ring 110 and the corrugated gasket 130 located thereon is shown. Figure 4A Embodiment of the present invention. The fixing of the corrugated gasket 130 is achieved by pressing downwards along the arrow F, which, due to the larger diameter of the corrugated gasket 130 compared to the annular recess 123, leads to a bending of the corrugated gasket 130 and thus to pressing into the piston body 120. Due to the bending stress, the corrugated gasket 130 can no longer loosen by itself, and the sealing ring 110 is securely locked. In this case, no separate locking means 140 is provided. Instead, the locking is achieved by a special geometry or size of the locking element 130 and the piston body 120.

[0048] All previous connections between the locking element 130 and the piston body 120 are releasable. However, according to further embodiments, an optional permanent connection (e.g., by welding, heat caulking, laser, ultrasound, etc.) can be formed between the locking element 130 and the piston body 120. The locking element 130 can then also be configured as a simple gasket.

[0049] Figure 5 A flow chart of a method for manufacturing a pneumatic piston 100 is schematically shown. The method comprises the following steps:

[0050] - forming S110 a piston body 120 having a recess 125 for receiving the sealing element 110;

[0051] - inserting S120 the sealing element 110 into the recess 125 of the piston body 120 in order to seal the intermediate space between the pneumatic piston 100 and the piston housing 20; and

[0052] The sealing element 110 is locked S130 in the recess 125 by means of the securing element 130 .

[0053] Figure 6 A possible use of a folding core 150 (or a collapsible core) for producing a piston body 120 with a recess 125 is shown. This is possible in particular if the piston body 120 is produced from a plastic material in an injection molding process. For this purpose, a folding core 150 (or a collapsible core) is provided. Figure 6 Only the inner mold 160 is shown in FIG. 1 ) and the foldable core 10 is unfolded, as in Figure 6 After the exemplary injection molding, the folding core 150 can be shrunk again so that the piston body 120 can be removed together with the recess 125 .

[0054] According to another embodiment, it is also possible to use a folding core for the O-ring groove. In this case, a locking ring is no longer required, but there is a risk that the tightness is impaired by the multiple partings on the folding core.

[0055] It should be understood that all the features of the previously described pneumatic piston 100 can also be constructed by other optional method steps. It should also be understood that the order mentioned is not necessarily the order in which the method steps are implemented. The steps can also be implemented in other orders or only a part of the method steps can be implemented.

[0056] The embodiment mainly provides the following advantages:

[0057] The securing ring or securing element 130 can form an additional guide for the piston, which results in the advantage that the guide length is extended during the internal piston guidance, thereby achieving better guidance.

[0058] The groove 142 in the piston can be produced cost-effectively, for example by means of a folded core.

[0059] The features of the invention disclosed in the description, the claims and the drawings may be essential for the implementation of the invention both individually and in any combination.

[0060] Reference numerals list

[0061] 20 Piston housing

[0062] 25 Chamber in piston housing

[0063] 100 Pneumatic piston

[0064] 110, 127 sealing elements

[0065] 120 Piston body

[0066] 123 Annular depression

[0067] 125 Notch

[0068] 130 Locking element

[0069] 133 Radial protrusion

[0070] 135 Incision

[0071] 140 Locking element

[0072] 142 slots

[0073] 144 Side concave

[0074] 145, 146 (hook-shaped) projection

[0075] 150 Folding core

[0076] 160 internal mold.

Claims

1. A pneumatic piston (100) for an electronic pneumatic modulator, wherein: The modulator has a piston housing (20; 21, 22) having a chamber (25) for receiving the pneumatic piston (100), wherein the pneumatic piston (100) is characterized in that: - a sealing element (110) for sealing the intermediate space between the pneumatic piston (100) and the piston housing (20; 21, 22); - a piston body (120) having a recess (125) for receiving the sealing element (110); and A securing element (130) which is designed to secure the sealing element (110) in the recess (125) in a form-fitting manner.

2. The pneumatic piston according to claim 1, Features: A locking element (140) is configured to lock the securing element (130) on the piston body (120).

3. The pneumatic piston according to claim 2, It is characterized in that The locking element (140) includes at least one of the following: - a groove (142), - at least one undercut (144), - At least one hook-shaped projection.

4. A pneumatic piston according to any one of the preceding claims, It is characterized in that The locking element (130) includes one of the following: a locking ring, in particular a clamping ring, which can be snapped into the groove (142) according to claim 3, - two half-rings which can be locked in the groove according to claim 3 and / or in the at least one undercut (144) and / or in the at least one hook-shaped projection, a toothed or non-toothed corrugated washer having a diameter selected such that it locks into the piston body (120) when inserted, at least one projection (133) which can be inserted into the at least one undercut (144) and / or into the at least one hook-shaped projection, - at least one notch (135) into which a projection (145) on the piston body (120) can engage in radial direction in order to prevent a relative rotation between the locking element (130) and the piston body (120).

5. A pneumatic piston (100) according to any one of the preceding claims, It is characterized in that Use at least one of the following materials: - the sealing element (110) comprises rubber or plastic, - the piston body (120) comprises plastic or metal, - The locking element (130) comprises plastic or metal.

6. A pneumatic piston (100) according to any one of the preceding claims, It is characterized in that The piston body (120) has the shape of a hollow cylinder or a cylinder, and the sealing element (110) and the locking element (130) are on a surface located radially inward.

7. An electro-pneumatic modulator for a braking system of a commercial vehicle, wherein: The modulator includes the following: - a pneumatic piston (100) according to any one of the preceding claims; and - A piston housing (20) having a chamber (25) for receiving the pneumatic piston (100).

8. A method for manufacturing a pneumatic piston (100), Features: - forming (S110) a piston body (20) having a recess (125) for receiving the sealing element (110); - inserting (S120) a sealing element (110) into a recess (125) of the piston body (120) in order to seal the intermediate space between the pneumatic piston (100) and the piston housing (20); and - The sealing element (110) is locked (S130) in the recess (125) by means of a locking element (130).

9. The method according to claim 8, It is characterized in that The step of forming (S110) the piston body (120) is performed by means of a folding core.

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