WO2016012013A1

WO2016012013A1 - Non-polar running surface for disengaging systems for reducing stick-slip effects and noise

Info

Publication number: WO2016012013A1
Application number: PCT/DE2015/200375
Authority: WO
Inventors: Jérémy Keller; Kirill PROKHOROV
Original assignee: Schaeffler Technologies AG & Co. KG
Priority date: 2014-07-24
Filing date: 2015-06-17
Publication date: 2016-01-28
Also published as: EP3172448A1; CN106662129A; DE102014214512A1; DE112015003411A5

Abstract

The invention relates to a cylinder arrangement (1) with at least one cylinder (3) and a piston (4) arranged therein, the piston (4) comprising at least one sealing element (2) for sealing the components piston (4) and cylinder (3), which are movable relative to one another, and at least one contact lip (5) with a circumference (6), which is configured to circumferentially bear in the installation in a displaceable manner on a corresponding sealing surface of the cylinder (3) and thus provide a sealing effect; wherein at least the sealing surface is made of a non-polar material (8).

Description

Non-polar tread for release systems to reduce stick-slip effects and noise

The invention relates to a cylinder arrangement, at least comprising a cylinder and a piston arranged therein, wherein the piston has at least one sealing element for sealing the relatively movable components piston and cylinder; and a hydraulic or pneumatic return system for a friction clutch, in particular for a motor vehicle.

In the prior art, various sealing elements are known which are suitable for sealing in a hydraulic system. However, due to the spring force of the contact lip and the frictional contact with the corresponding sealing surface, a so-called stick-slip effect can occur, that is to say the contact lip lifts off due to the friction and the pretension and sinks again, thus producing an audible noise. for example, a rattle or squeak. This effect is reduced with some materials, such as silicone based gaskets. However, such materials are not compatible with all common media, for example brake fluids. For example, EPDM (ethylene-propylene-diene rubber) gaskets can be used over a wide range of media. However, this material tends to squeak due to a pronounced Stick-Sl ip effect. On this basis, the present invention has the object, at least partially overcome the known from the prior art disadvantages. The object is solved by the features of independent claim 1. Advantageous developments are the subject of the dependent claims. The invention relates to a cylinder arrangement having at least one cylinder and a piston arranged therein, wherein the piston has at least one sealing element for sealing the relatively displaceable components piston and cylinder and comprises at least one contact lip with a circumference, which is adapted to abut slidably in installation on a corresponding sealing surface of the cylinder and thus set a sealing effect; wherein at least the sealing surface consists of a non-polar material.

The cylinder arrangement comprises, for example, a sealing element of a piston, for example a master piston or slave piston of a hydraulic or pneumatic return system, which serves to seal a hydraulic fluid or a pneumatic gas with respect to the environment. For this purpose, the sealing element has a contact lip which rests on a corresponding sealing surface and carries out a movement relative to the sealing surface. The contact lip is pressed against the sealing surface in such a way that no or only a negligible amount of the hydraulic fluid or of the pneumatic gas can break through this barrier. The contact lip not only has to apply the force to the contact lip, but it can also be set up so that it is supported by the fluid and the contact lip is additionally pressed against the corresponding sealing surface.

In particular, the material is a polypropylene or polyethylene. These thermoplastics from the group of thermoplastics have low intermolecular forces.

These intermolecular forces are binding forces that combine valently saturated molecules into molecular assemblies. They work over long distances. The term Van der Waals forces is used synonymously.

A comparison of thermoplastics with thermosets makes it clear that the direct linking of polymer chains by atomic bonds has a very large influence on the properties of plastics. But the intermolecular forces (also called minor valences) between the macromolecules play a major role. Since the polymer chains are extremely long, the forces between these chains become very large. Polymer chains possessing polar groups are attracted to each other by dipole-dipole forces. These forces are not as strong as the hydrogen bridges, but much higher than nonpolar plastics such as polyethylene. Nonpolar plastics, such as polyethylene or polypropylene, have much lower softening ranges than other plastics because their polymer chains are held together only by the weak van der Waals forces.

The use of nonpolar material at least for the sealing surface allows the use of sealing elements, which consist of EPDM. The usually occurring Stick-Sl ip effect is reduced here and / or completely suppressed. This is due to the fact that between the sealing element and the sealing surface now lower intermolecular forces act, so that a juxtaposition of sealing element and sealing surface is overcome faster.

According to a preferred embodiment, the cylinder consists of the nonpolar material. In particular, the housing of the cylinder is made entirely of the nonpolar material. In particular, at least the sealing surface

Formed by a coating of a cylinder inner wall, wherein the coating (exclusively) comprises the non-polar material; or

• formed by a sleeve which is arranged on the cylinder inner wall, wherein the sleeve (exclusively) consists of the non-polar material; or

· Produced by a 2K process (2-component process).

In a 2K process, different materials are assembled into a final product in a common manufacturing process. In particular, 2K injection molding processes are meant herewith. This can z. For example, harder plastics can be processed together with nonpolar material, so that, for example, B. a cylinder inner wall at least in the region of the sealing surface of non-polar material and in particular all other areas of the cylinder made of the harder plastic. There- At both materials are materially connected to each other. Cohesive compounds are in particular called all compounds in which the connection partners are held together by atomic or molecular forces. At the same time, they are non-detachable compounds that can only be separated by destroying the connectors.

In particular, the cylinder is a master cylinder, a semi-slave cylinder or a slave cylinder. The distinction between the individual cylinders is familiar to the person skilled in the art.

In particular, the cylinder is a master cylinder with a primary sealing element and a secondary sealing element (ie, two sealing elements), wherein both sealing elements are arranged on the piston and at least the secondary sealing element bears with the contact lip on the sealing surface and is moved along the sealing surface.

The primary seal seals the wake region of the cylinder from the actuation and / or the environment. The trailing edge of a master cylinder is the area between the primary sealing element and the secondary sealing element, which is filled from a reservoir of the fluid (pressureless). The secondary sealing element seals the pressure chamber from the (non-pressurized) wake region. The pressure chamber is fluidly connected in particular with the slave cylinder via a pressure line, so that flows through the actuation of the master cylinder fluid from the pressure chamber of the master cylinder via the pressure line to the slave cylinder and thus the slave cylinder is actuated.

The nonpolar material can be used in particular (also / additionally) for the sealing surface, which cooperates with the primary sealing element of the cylinder arrangement.

According to a further aspect of the invention, a hydraulic or pneumatic return system for a friction clutch is proposed, having at least the following components:

A master cylinder arrangement with a master piston in a master cylinder, A slave cylinder arrangement with a slave piston in a slave cylinder,

wherein the master cylinder arrangement and the slave cylinder arrangement communicate with each other in terms of flow, so that a movement of the master piston can be converted into a movement of the slave piston, wherein at least one of the cylinder arrangements comprises a cylinder arrangement according to the invention, wherein by means of the at least one sealing element the piston can be sealed relative to the associated cylinder such that an overflow of a fluid in the associated cylinder can be prevented in at least one direction.

The hydraulic or pneumatic return system consists of a master piston, which can compress a master volume in a master cylinder and a corresponding slave piston, which is moved in a slave cylinder as a result of an increase in volume in the slave cylinder. Contrary to the naming of the piston and the slave piston, a retrograde transfer of forces is also possible. In addition, a translation can take place by different piston surfaces or other elements. At least one of the cylinder arrangements is carried out according to the invention, wherein due to the design of the sealing surface of a non-polar material only a small stick-slip effect occurs. In the contact between the sealing surface and the contact lip, a stick-slip effect is particularly preferably suppressed to such an extent that noise no longer takes place and achieves a significantly improved sealing effect over all operating states (piston speed, pressure conditions in the pressure space / wake region, type of fluid, temperature of the fluid) becomes.

Furthermore, a friction clutch with an axis of rotation for releasably connecting an output shaft to a drive train is proposed, which has at least the following components:

At least one friction pack, wherein a torque can be transmitted via the friction pack in the pressed-on state;

A return system according to the above description for actuating the friction pack by means of the slave piston. The friction clutch is adapted to releasably transfer torque from an output shaft to a drive train and vice versa. As a rule, this is achieved via the at least one friction pack, as described above, which has an axially displaceable pressure plate which is rotationally fixed, as a rule with the output shaft, which can be pressed against at least one corresponding friction disk and then transmits a torque can. The force is generated by an actuating system which is actuated directly or indirectly by a user. From this actuation system, the force goes out, which leads to an axial compression of the at least one Reibpakets. Particularly preferably, the actuating system is arranged hydraulically or pneumatically, whereby particularly large axial forces can be generated and a transmission ratio is easily adjustable. Here, the use of a cylinder assembly according to the above description is advantageous because noise can disturb the driver.

Furthermore, a motor vehicle is proposed which has a drive unit with an output shaft, a drive train and a friction clutch according to the above description for releasably connecting the output shaft to the drive train.

Most motor vehicles today have a front-wheel drive and therefore preferably arrange the drive unit, for example an internal combustion engine or an electric motor, in front of the driver's cab and transversely to the main drive direction. The space is particularly small in such an arrangement and it is therefore particularly advantageous to use a friction clutch small size.

The installation space situation for passenger cars of the small car class according to European classification is exacerbated. The units used in a passenger car of the small car class are not significantly reduced compared to passenger cars larger car classes. Nevertheless, the available space for small cars is much smaller. The here cylinder arrangement allows noise-free operation of a hydraulic release. This is for the Driver particularly pleasant and for small cars, the hydraulic actuation prevails due to increasing component quantities.

Passenger cars are classified according to vehicle class according to, for example, size, price, weight, power, but this definition is subject to constant change according to the needs of the market. In the US market, vehicles of the class small cars and microcars are classified according to European classification of the class of Subcompact Car and in the British market they correspond to the class Supermini, for example, the class City Car. Examples of the micro car class are a Volkswagen Fox or a Renault Twingo. Examples of the small car class are an Alfa Romeo Mito, Volkswagen Polo, Ford Fiesta or Renault Clio.

The features listed individually in the claims can be combined with one another in any technologically meaningful manner and can be supplemented by explanatory facts from the description and details from the figures, wherein further embodiments of the invention are shown.

The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Like reference numerals designate like objects. Show it:

Fig. 1: a master cylinder arrangement in section;

FIG. 2 shows a detail of the master cylinder arrangement according to FIG. 1; FIG.

Fig. 3: the master cylinder assembly of Figure 1 in the actuated state.

4 shows a detail of the master cylinder arrangement according to FIG. 3;

Fig. 5: a return system with friction clutch; Fig. 6: a motor vehicle.

1 shows a cylinder arrangement 1, wherein here a master cylinder arrangement 15 with a master cylinder 20 is shown. Via an actuation 43, the piston 4 is moved within the cylinder 3. The piston 4 has a primary sealing element 13 and a secondary sealing element 14. The primary seal 13 seals the trailing region 38 of the cylinder 3 with respect to the actuator 43 and / or the environment (outside of the cylinder 3). The trailing region 38 of a master cylinder 20 is the region between the primary sealing element 13 and the secondary sealing element 14, which is filled from a reservoir of the fluid 23 (without pressure) via an inlet 44. The secondary sealing element 14 seals the pressure chamber 37 at least in relation to the (non-pressurized) wake region 38, so that no fluid 23 can escape from the pressure chamber 37 in this direction 45. The pressure chamber 37 is in particular fluidly connected to a slave cylinder 22 (not shown) via a pressure line 35 so that fluid 23 flows from the pressure chamber 37 of the master cylinder 20 via the pressure line 35 to the slave cylinder 22 and thus the slave cylinder through actuation of the master cylinder 20 22 is pressed. The secondary sealing element 14 moves here with the master piston 19 along the sealing surface 7 on the cylinder inner wall 10. The cylinder 3 has on the side of the actuator 43 a stop ring 40 which limits the path of the piston 4 and the actuator 43 in a direction 45. The stop ring 40 cooperates with an O-ring 41 to seal the cylinder. 3

FIG. 2 shows a detail of the master cylinder arrangement 15 according to FIG. 1. The secondary sealing element 14 is arranged on the piston 4 and has a contact lip 5, which rests on a corresponding, formed on the cylinder inner wall 10, sealing surface 7 and relative to the sealing surface 7 performs a movement. The contact lip 5 is pressed against the sealing surface 7 such that no or only a negligible amount of the hydraulic fluid 23 or of a pneumatic gas can break through this barrier. The sealing surface 7 within the housing 39 of the cylinder 3 is formed here by a non-polar material 8. This material 8 can be arranged on the cylinder inner wall 10 as a coating 9, as a sleeve 11 or as a result of a 2K process 12.

FIG. 3 shows the master cylinder arrangement 15 from FIG. 1 in the actuated state. The piston 4 has been moved along the direction 45 toward the pressure line 35, so that fluid 23 exits the pressure chamber 37 and is fed via the pressure line 35 to a slave cylinder 22. In this case, the secondary sealing element 14 was moved along the sealing surface 7 in the direction 45. The return spring 42 in the pressure chamber 37 is tensioned, so that the restoring spring exerts a restoring force on the piston 4.

FIG. 4 shows a detail of the master cylinder arrangement 15 according to FIG. 3. The contact lip 5 of the secondary sealing element 15 is moved along the direction 45 along the sealing surface 7 and furthermore seals the trailing region 38 with respect to the surroundings or with respect to the actuation 43.

5 shows a hydraulic or pneumatic return system 17, wherein in a master cylinder arrangement 15 a master piston 19 can be actuated in a master cylinder 20 via a clutch pedal 33. The master piston 19 is sealed relative to the master cylinder 20 by means of a sealing element 2, as shown for example in FIGS. 2 and 4, and thus a fluid 23 in the master cylinder 20 can be influenced by the master piston 19. Through the pressure line 35, the fluid 23 is pressed upon actuation of the clutch pedal 33 in the slave cylinder 22 of a slave cylinder assembly 16 and by another sealing element 2, as shown for example in Fig. 1, the effect of the flowing fluid 23 to the slave piston 21 transmitted. The latter, in turn, actuates a disc spring 36, which thus disengages the friction pack 27 of a friction clutch 18, so that a torque which is applied to an output shaft 25 is no longer transmitted to the transmission shaft 34. The friction clutch 18 has an axis of rotation 24 about which the elements of the friction clutch 18 rotate. In Fig. 6, a motor vehicle 28 is shown with a drive unit 29, which is arranged with its motor axis 32 transverse to the longitudinal axis 31 in front of the driver's cab 30. The drive unit 29 is shown here as an internal combustion engine, which is connected via an output shaft 25 by means of a friction clutch 18, which has a rotation axis 24 in alignment with the motor axis 32, to a drive train 26 shown purely schematically here.

Cylinder arrangement

sealing element

cylinder

piston

contact lip

scope

sealing surface

material

coating

Cylinder inner wall

shell

2K process

Primary sealing element

Secondary sealing element

Master cylinder arrangement

Slave cylinder arrangement

hydraulic or pneumatic reverse system friction clutch

master piston

Master cylinder

slave piston

slave cylinder

fluid

axis of rotation

output shaft

powertrain

Reibpaket

motor vehicle

drive unit

cab Longitudinal axis Motor shaft Clutch pedal Transmission shaft Pressure line Disc spring Pressure chamber Caster area Housing Stop ring O-ring

Return spring actuation inlet

direction

Claims

claims

Cylinder assembly (1) with at least one cylinder (3) and a piston arranged therein (4), wherein the piston (4) at least one sealing element (2) for sealing the relatively movable components piston (4) and cylinder (3) and at least one contact lip (5) with a circumference (6) encompasses, which is adapted to slidably abut in installation on a corresponding sealing surface (7) of the cylinder (3) and thus set a sealing effect;

characterized in that at least the sealing surface (7) consists of a non-polar material (8).

A cylinder assembly (1) according to claim 1, wherein the material (8) is a polypropylene or polyethylene.

Cylinder arrangement (1) according to one of the preceding claims, wherein the cylinder (3) consists of the material (8) or at least the sealing surface (7).

• is formed by a coating (9) of a cylinder inner wall (10); or

• By a sleeve (1 1) is formed, which is arranged on the cylinder inner wall (10); or

• is made by a 2K process (2-component process) (12).

Cylinder arrangement (1) according to one of the preceding claims, wherein the cylinder (3) is a master cylinder (20), a semi-slave cylinder or a slave cylinder (21).

5. Cylinder arrangement (1) according to one of claims 1 to 3, wherein the cylinder (3) is a master cylinder (20) having a primary sealing element (13) and a secondary sealing element (14), wherein both sealing elements (13, 14) on the piston (4) are ordered and at least the secondary sealing element (14) with the contact lip (6) against the sealing surface (8) and is moved along the sealing surface (8).

6. Hydraulic or pneumatic return system (17) for a friction clutch (18), comprising at least the following components:

A master cylinder arrangement (15) having a master piston (19) in a master cylinder (20),

A slave cylinder arrangement (16) with a slave piston (21) in a slave cylinder (22),

wherein the master cylinder arrangement (15) and the slave cylinder arrangement (16) communicate with one another in terms of flow, so that a movement of the master piston (19) into a movement of the slave piston (21) can be implemented, wherein at least one of the cylinder arrangements (15, 16) at least one cylinder arrangement (1 ) according to one of the preceding claims, wherein by means of the at least one sealing element (2) the piston (7, 19, 21) relative to the associated cylinder (6, 20, 22) is sealable such that an overflow of a fluid (23) in associated cylinder (6, 20, 22) in at least one direction (45) can be prevented.