DE102018105477A1 - Piston rod of a hydraulic cylinder and hydraulic cylinder for a clutch or brake system - Google Patents

Abstract

The invention relates to a piston rod (1) of a hydraulic cylinder (5), in particular a master cylinder, for actuating a clutch or brake system, wherein the piston rod (1) has a high performance plastic or a carbon layer to increase the wear resistance of the piston rod (1) and Furthermore, the invention relates to a hydraulic cylinder (5), in particular a master cylinder, for actuating a clutch or brake system with a piston rod (1).

Description

The invention relates to a piston rod of a hydraulic cylinder, in particular a master cylinder, for actuating a clutch or brake system.

Furthermore, the invention relates to a hydraulic cylinder, in particular a master cylinder, for actuating a clutch or brake system with a piston rod.

Known hydraulic cylinders or clutch master cylinder for actuating a clutch system have a housing made of a thermoplastic material, in which a pressure chamber is formed, which is filled with hydraulic fluid, usually a brake fluid.

The pressure chamber is formed between the housing and an axially displaceable in the housing piston member or piston of a thermoplastic material.

Here, the hydraulic cylinder has two seals, a secondary seal and a primary seal, which are each connected to the piston element and are moved with this. For both gaskets, EPDM or a liquid silicone, such as LSR, can be used as the material.

However, hydraulic cylinders of such design have increased wear on the piston rod and on the other side of the housing on a seal, which can lead to the failure of a clutch or brake system.

It is therefore an object of the present invention to provide a piston rod of a hydraulic cylinder and a hydraulic cylinder for actuating a clutch or brake system, which or is formed wear and material can be produced to save material.

This object is achieved by the features of the independent claims. Further advantageous developments are the subject of the dependent claims.

According to the invention, in a first aspect of the present invention, a piston rod of a hydraulic cylinder, in particular a master cylinder, for actuating a clutch or brake system to a high-performance plastic or a carbon layer. As a result, the wear resistance of the piston rod can be increased and the sliding friction with other components of a hydraulic cylinder can be reduced.

Further, it is preferable that the high-performance plastic is a polyamide-imide (PAI) or a polyether-ether-ketone (PEEK).

It is also possible that the high performance plastic is a polyether ketone (PEK), a polyphenylene sulfide (PPS), a polysulfone (PSU), and / or a polyethersulfone (PESU or PES).

Further, it is preferable that the piston rod is coated with a carbon layer.

The piston rod is preferably coated with a plasma polymer layer, a diamond-like carbon (DLC) layer, a CVD diamond layer and / or a graphite layer.

A second aspect of the present invention comprises a hydraulic cylinder, in particular a master cylinder, for actuating a clutch or brake system.

It is expressly understood that the features of the piston rod, as mentioned in the first aspect, can be used individually or in combination with each other in the hydraulic cylinder application.

In other words, the piston rod features mentioned above under the first aspect of the invention can also be combined here with further features in the second aspect of the invention.

Preferably, a hydraulic cylinder, in particular a master cylinder, for actuating a clutch or brake system, a piston rod according to the first aspect of the present invention for applying force to a piston member.

• - ein Gehäuse und
• - ein Kolbenelement, das innerhalb des Gehäuses axial verschiebbar angeordnet ist,
• - wobei zwischen dem Gehäuse und dem Kolbenelement ein mit Fluid gefüllter Druckraum gebildet wird.

It is further preferred that the hydraulic cylinder comprises:

• - a housing and
• a piston element which is arranged axially displaceable within the housing,
• - Wherein between the housing and the piston member, a fluid-filled pressure chamber is formed.

Preferably, the piston rod along the displacement of the piston member, which is inserted into the housing, a high-performance plastic or a carbon layer.

In other words, advantageously, only the part of the piston rod is coated with a carbon layer, which is in the housing movable retracts and / or rubs when entering the housing on a component or touches this.

Furthermore, it is advantageous if the housing has a thermoplastic material.

Preferably, the piston member comprises a thermoplastic resin and desirably a carbon layer.

Furthermore, it is favorable if the piston rod is arranged on the piston element and comprises a stop element for limiting its displacement path.

Conveniently, the stop element cooperates with a retaining element arranged on the housing of the hydraulic cylinder in order to limit the axial extension movement of the piston element out of the housing.

It is also advantageous if the hydraulic cylinder further comprises a holding element for forming a stop for the stop element of the piston rod.

Advantageously, the retaining element is arranged on the housing.

Conveniently, the retaining element steel as a material.

Preferably, the retaining element is designed as a retaining clip with two legs, so that the piston rod is freely executable between the legs, wherein the distance between the two legs is greater than the diameter of the piston rod is formed.

Furthermore, it is advantageous if the holding element is U-shaped.

Preferably, the housing of the hydraulic cylinder comprises recesses for receiving the retaining element.

It is also advantageous if the holding element, in particular its two legs of the U-shape, is inserted into the recesses.

Advantageously, the legs of the retaining element can be inserted transversely to the axial direction of the hydraulic cylinder in the recesses.

Furthermore, it is advantageous if the distance between the two legs of the holding element is smaller than the diameter of a stop element of the piston rod is formed.

It can also be provided that the piston element comprises at least one seal in order to seal the pressure chamber of a housing of the hydraulic cylinder.

Conveniently, the piston element has a primary seal and a secondary seal for sealing the pressure chamber.

Furthermore, it is possible that the hydraulic cylinder comprises a return spring.

Advantageously, the return spring is arranged in the housing of the hydraulic cylinder, that the piston element is displaced axially against the spring force of the return spring upon actuation of the hydraulic cylinder via the associated piston rod to apply a corresponding pressure by fluid displacement in a slave cylinder.

Hereinafter, the inventive idea presented above is expressed in other words in addition.

This idea preferably relates - in simplified terms - to two core ideas, namely to use a wear-resistant plastic as an alternative material for a piston rod of a hydraulic cylinder and / or to provide a piston rod of a hydraulic cylinder with a wear-resistant coating.

In summary, on the one hand the wear can be reduced / prevented on the one hand by a wear-resistant plastic, so that fewer or no particles are produced which originate from the piston rod and increase the friction in the hydraulic cylinder.

On the other hand, there is preferably the possibility of coating components with a carbon layer in order to make them more resistant to wear.

In this case, the previously used material for a piston rod can be maintained, only that the piston rod is provided with a coating that gives the piston rod a more wear-resistant surface.

With both possible solutions, the aim is to prevent / minimize the wear, so that a frictional contact of the piston rod, preferably with a retaining clip, is associated with less / no wear.

In more detail, it is advantageous to use a wear-resistant plastic as an alternative material for a piston rod.

Plastics which have a higher wear resistance than known materials for piston rods are advantageously plastics from the field of high-performance plastics.

Typical representatives here are, for example, polyamide-imides (PAI) or polyether-ether-ketones (PEEK).

Plastics from these groups preferably contain aromatic structures in their polymer chains which, in addition to the increased wear resistance, confer further advantages over other standard technical plastics (eg polyamide, etc.) (eg better temperature resistance, higher chemical resistance, etc.) ,

When using such a plastic as a piston rod material instead of, for example, previously used polyamide 66 wear can be significantly reduced / prevented, so that less / no plastic particles caused by, for example, abrasion.

Furthermore, it is possible, as already mentioned above, to provide the piston rod with a wear-resistant coating.

A wear-resistant coating is, for example, a DLC coating (diamond-like carbon).

These are diamond-like (amorphous) carbon layers which can be firmly adhered to a carbon-containing plasma on almost all metals and metal alloys, hard metals and light metals, but also on non-metals (such as plastic).

Due to the various process parameters of the process, e.g. the duration of treatment may influence the properties of the DLC layers (eg layer thickness).

The DLC coating advantageously causes both a reduction in the sliding friction and a higher wear resistance.

If the piston rod is provided with such a coating, the wear can be significantly reduced / prevented, resulting in less / no plastic particles, for example due to abrasion.

• 1 eine Schnittansicht auf einen erfindungsgemäßen Hydraulikzylinder mit einer Kolbenstange einem ersten Zustand;
• 2 eine Schnittansicht auf einen erfindungsgemäßen Hydraulikzylinder mit einer Kolbenstange einem zweiten Zustand; und
• 3 eine Schnittansicht durch das Gehäuse des erfindungsgemäßen Hydraulikzylinders zur Darstellung eines Halteelements.

The invention will be explained in more detail with reference to an embodiment in conjunction with accompanying drawings. Here are shown schematically:

• 1 a sectional view of a hydraulic cylinder according to the invention with a piston rod a first state;
• 2 a sectional view of a hydraulic cylinder according to the invention with a piston rod a second state; and
• 3 a sectional view through the housing of the hydraulic cylinder according to the invention for illustrating a holding element.

In the following description, like reference characters will be used for like items.

1 shows a sectional view of a hydraulic cylinder according to the invention 5 with a piston rod 1 a first state.

Shown in more detail 1 a piston rod 1 of the hydraulic cylinder 5 , in particular a master cylinder, for actuating a clutch or brake system.

Here, the piston rod 1 a high-performance plastic to the wear resistance of the piston rod 1 increase and the sliding friction with other components of the hydraulic cylinder 5 to reduce.

In the present case is used as a high performance plastic polyetheretherketone.

Alternatively, it is also possible that the piston rod 1 a carbon layer. A carbon layer may be a plasma polymer layer, a diamond-like carbon (DLC) layer, a CVD diamond layer, and / or a graphite layer.

Further shows 1 a hydraulic cylinder 5 , in particular a master cylinder, for actuating a clutch or brake system, wherein the piston rod 1 for applying force to a piston element 9 serves.

Also is in 1 to realize that the hydraulic cylinder 5 a housing 13 includes, in which the piston element 9 is arranged axially displaceable.

Between the case 13 and the piston element 9 is formed with a fluid-filled pressure chamber.

The housing 13 is made of a thermoplastic. In contrast, as already mentioned, the piston element 9 made of a high-performance plastic.

The piston rod 1 is on the piston element 9 arranged and includes to limit the displacement of a stop element 4 ,

Here, the stopper acts 4 with one on the case 13 of the hydraulic cylinder 5 arranged holding element 6 together to the axial extension movement of the piston member 9 out of the case 13 to limit.

Furthermore, the hydraulic cylinder has 5 as previously mentioned, a holding element 6 to form a stop for the stop element 4 the piston rod 9 ,

The holding element 6 is on the case 13 arranged and has steel as a material.

Furthermore, in 1 to realize that the piston element 9 two seals 7 . 8th has the pressure chamber of the housing 13 of the hydraulic cylinder 5 tight.

The piston element has been shown in more detail 9 a primary seal 7 and a secondary seal 8th to the seal of the pressure chamber.

Furthermore, in 1 shown that the hydraulic cylinder 5 a return spring 10 includes that in the housing 13 of the hydraulic cylinder 5 is arranged that the piston element 9 upon actuation of the hydraulic cylinder 5 over the piston rod connected to it 1 axially against the spring force of the return spring 10 is moved. This makes it possible to apply a corresponding pressure by fluid displacement in a slave cylinder.

Regarding the piston rod 1 shows 1 to that on the one hand a pedal connection 3 and on the other hand via an articulated connection 2 with the piston element 9 connected is.

Furthermore is 1 to see that the hydraulic cylinder 5 via a tail pipe 12 as well as a high pressure connection 11 features.

Im after 1 shown state is the piston rod 1 in the maximum extended position, in which the stop element 4 the piston rod 1 on the holding element 6 of the housing 13 is applied.

2 shows a sectional view of a hydraulic cylinder according to the invention 5 with a piston rod 1 a second state, wherein 3 a sectional view through the housing 13 the hydraulic cylinder according to the invention 5 for the representation of a holding element 6 shows.

In the following, for the sake of simplicity, the 2 and 3 described together, with the particular features of the figures is also discussed.

To avoid unnecessary repetition is on the statements concerning 1 referenced, the analogous to the 2 and 3 are applicable.

Therefore, on the one hand on the differences between the figures and on the other hand the hydraulic cylinder according to the invention will be discussed below 5 with a piston rod 1 described further, with the further description also on 1 in a similar way applies.

First, it should be noted that when comparing the 1 and 2 in 2 a force on the piston rod 1 acting, this together with the piston element 9 against the spring force of the return spring 10 pushes or moves.

You can see here, represented by a circle in 2 that the piston rod 1 the stop element 6 touchingly contacted. Responsible in the case of such a contact process is friction, which normally leads to abrasion in a piston rod of the prior art.

In contrast, in the embodiment of the piston rod according to the invention 1 with a high-performance plastic or with a carbon layer on the piston rod 1 no abrasion of material on the piston rod 1 be prevented.

3 however, shows that the retaining element 6 is designed as a retaining clip with two legs, so that the piston rod 1 freely between the legs is feasible, wherein the distance between the two legs greater than the diameter of the piston rod 1 is trained.

Also is 3 to see that the retaining element 6 U-shaped, wherein the housing 13 of the hydraulic cylinder 5 Recesses for receiving the retaining element 6 Has.

With reference to 3 It can also be seen that the retaining element 6 or whose two legs of the U-shape are inserted into the recesses, wherein the legs of the holding element 6 transverse to the axial direction of the hydraulic cylinder 5 are inserted into the recesses.

Also shows 3 in that the distance between the two legs of the retaining element 6 smaller than the diameter of the stop element 4 the piston rod 1 is trained. In this way, it is possible that the stop element 4 at the retaining elements 6 strikes and thus the extract of the piston rod 1 out of the case 13 of the hydraulic cylinder 5 is limited.

Below are the 1 to 3 again described with partially different words.

So has a hydraulic cylinder 5 or a clutch master cylinder for actuating a clutch system (see. 1 and 2 ), via a housing 13 made of a thermoplastic material.

Inside the case 13 there is an axially displaceable piston 9 or a piston element 9 , also made of a thermoplastic material, which has two seals 7 . 8th features that with the piston 9 are connected and with the piston 9 to be moved.

At the seals 7 . 8th it is a primary seal 7 and a secondary seal 8th , In the present embodiment, a liquid silicone (LSR) is used as a material for seals.

Between the piston element 9 and the housing 13 a pressure space is formed, which is filled with hydraulic fluid (brake fluid).

When operating the hydraulic cylinder 5 becomes the piston 9 or the piston element 9 via a piston rod connected to it 1 axially against the spring force of a return spring 10 moved to apply a corresponding pressure in a slave cylinder.

The primary seal allows this 7 the pressure build-up in the direction of slave cylinder, while holding the secondary seal 8th the fluid pressure in the wake area.

The piston 9 is, as already described above, with the piston rod 1 connected to a stop plate 4 or a stop element 4 has (see. 1 and 2 ).

The stop plate 4 or the stop element 4 acts with one on the housing 13 attached retaining clip 6 (steel) or with a holding elements 6 together to the axial extension movement of the piston rod 1 and also the piston element 9 out of the case 13 to limit.

The retaining clip 6 or the holding elements 6 is U-shaped, as in 3 to recognize.

Here, the holding elements comprises 6 - to rest on the retaining plate 4 or on the stop element 4 - Two leg parts, which are transverse to the longitudinal direction of the hydraulic cylinder 5 through the housing 13 extending recesses are inserted.

The retaining clip or the retaining elements 6 thus extends radially through corresponding recesses on the top and bottom of the housing 13 ,

The distance between the two legs of the retaining element 6 is slightly smaller than the diameter of the stop element 4 (see 1 to 3 ).

So that the piston rod 1 free between the legs of the retaining element 6 is feasible, the distance between the two legs of the retaining element 6 slightly larger than the diameter of the piston rod 1 (see 1 to 3 ).

In certain axial positions of the piston or the piston element 9 in combination with certain swivel angles and tilting of the piston rod 1 it can happen that the piston rod 1 in contact with the retaining clip 6 or with the holding element 6 arrives (compare 2 , Highlighting with circular ring).

Due to the relative movement between the piston rod 1 and retaining clip 6 It may be due to the direct friction contact for wear on the piston rod 1 come, which leads to the "production" of the plastic particles.

It should be mentioned that the retaining clip - due to the punching process - has rounded as well as sharp-edged sides, wherein the frictional contact of the piston rod 1 with sharp edges the wear is higher.

The resulting / ablated plastic particles in a piston rod from the prior art can by actuating the master cylinder in the grease in the region of the secondary seal 8th reach. It has been shown that it comes through the plastic particles of a piston rod from the prior art in the secondary chamber during actuation of the master cylinder reinforced to axial grooves on the silicone gaskets and the secondary side leakage is significantly enhanced by the particles in the grease.

On the other hand, with a piston rod according to the invention 1 the wear due to the frictional contact between the piston rod 1 and the retaining clip 6 or the holding element 6 minimizes or prevents, whereby the formation of plastic particles is minimized or prevented at this point. Thus, a negative influence on the secondary leakage can be eliminated.

LIST OF REFERENCE NUMBERS

1

piston rod

2

articulated connection

3

pedal connection

4

stop element

5

hydraulic cylinders

6

retaining element

7

primary seal

8th

secondary seal

9

piston element

10

Return spring

11

High pressure port

12

trailing socket

13

casing

Claims (10)

Piston rod (1) of a hydraulic cylinder (5), in particular a master cylinder, for actuating a clutch or brake system, characterized in that the piston rod (1) has a high performance plastic or a carbon layer to increase the wear resistance of the piston rod (1) and the To reduce sliding friction with other components of a hydraulic cylinder (5). Piston rod after Claim 1 , - wherein the high performance plastic is a polyamide imide or a polyetheretherketone. Piston rod after Claim 1 or 2 wherein the piston rod (1) is coated with a carbon layer, wherein preferably the piston rod (1) is coated with a plasma polymer layer, a diamond-like carbon (DLC) layer, a CVD diamond layer and / or a graphite layer , Hydraulic cylinder (5), in particular master cylinder, for actuating a clutch or brake system comprising: - A piston rod (1) according to one of the preceding claims for applying force to a piston element (9). Hydraulic cylinder after Claim 4 comprising: a housing (13) and a piston element (9) which is arranged axially displaceably within the housing (13), wherein between the housing (13) and the piston element (9) a fluid-filled pressure chamber is formed, - Wherein the piston rod (1) along the displacement of the piston member (9) which is insertable into the housing (13), a high-performance plastic or a carbon layer. Hydraulic cylinder after Claim 5 , - wherein the housing (13) comprises a thermoplastic material, - wherein preferably the piston element (9) comprises a thermoplastic material. Hydraulic cylinder according to one of the preceding claims, - wherein the piston rod (1) is arranged on the piston element (9) and for limiting the displacement of which comprises a stop element (4), - Preferably wherein the stop element (4) with a on the housing (13) of the hydraulic cylinder (5) arranged holding element (6) cooperates to limit the axial extension movement of the piston member (9) from the housing (13). Hydraulic cylinder after Claim 7 - wherein the hydraulic cylinder (5) further comprises a holding element (6) for forming a stop for the stop element (4) of the piston rod (9), - wherein preferably the holding element (6) on the housing (13) is arranged, - preferably the holding element (6) is designed as a retaining clip with two legs, so that the piston rod (1) is free between the legs feasible, wherein the distance between the two legs is greater than the diameter of the piston rod (1), - preferably wherein the holding element (6) is U-shaped, - wherein preferably the housing (13) of the hydraulic cylinder (5) recesses for receiving the holding element (6), - preferably wherein the holding element (6), in particular its two legs of the U-shape, is inserted into the recesses, - preferably wherein the distance between the two legs of the holding element (6) smaller than the diameter of a stop element (4) of the piston rod (1) form t is. Hydraulic cylinder according to one of the preceding claims, - wherein the piston element (9) comprises at least one seal (7, 8) in order to seal the pressure chamber of a housing (13) of the hydraulic cylinder (5), - wherein preferably the piston element (9) has a primary seal (7) and a secondary seal (8) for sealing the pressure chamber. Hydraulic cylinder according to one of the preceding claims, - wherein the hydraulic cylinder (5) comprises a return spring (10), wherein preferably the return spring (10) is arranged in the housing (13) of the hydraulic cylinder (5), that the piston element (9) upon actuation of the hydraulic cylinder (5) via the associated piston rod (1) axially against the spring force of the return spring ( 10) is displaced to apply a corresponding pressure by fluid displacement in a slave cylinder.

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