Piston and piston-equipped assembly for a hydraulic power unit or a piston-cylinder device of a vehicle braking system

Abstract

Piston (52) for a piston-cylinder device of a vehicle brake system, characterized by the fact that a sealing sleeve (54) is attached to at least one attachment point of the piston (52); and a contact surface (56) for the sealing sleeve (54) is formed on the piston (52), which has a shape curved away from the sealing sleeve (54); so that the sealing sleeve (54) can be pressed at least partially into a displacement volume (58) spanned by the contact surface (56) of the piston (52) by means of a pressure present on a side of the sealing sleeve (54) directed away from the piston (52), wherein the piston (52) with the sealing sleeve (54) attached thereto can be arranged adjustably within an internal volume (60) of the hydraulic unit or the piston-cylinder device such that a partial volume (62) of the internal volume (60) can be limited as a pressure chamber (62) by means of the sealing sleeve (54) and the piston (52), wherein the sealing sleeve (54) and the piston (52) can be adjusted against at least one spring force of at least one spring (64, 66) so that a filling volume of the pressure chamber (62) that can be filled with brake fluid can be increased.

Description

[0001] The invention relates to a piston and a piston-equipped assembly for a hydraulic power unit or a piston-cylinder device of a vehicle braking system. The invention also relates to a hydraulic power unit for a vehicle braking system, a piston-cylinder device for a vehicle braking system, and a vehicle braking system. Furthermore, the invention relates to a manufacturing method for a piston for a hydraulic power unit or a piston-cylinder device of a vehicle braking system and a manufacturing method for a piston-equipped assembly for a hydraulic power unit or a piston-cylinder device of a vehicle braking system. State of the art

[0002] Fig. Figure 1 shows a cross-section through a state-of-the-art pedal stroke simulator.

[0003] The in Fig. A schematic representation of a conventional pedal stroke simulator is installed in the Toyota Prius III. The conventional pedal stroke simulator has a housing consisting of a cast part 10 and a cover 12 inserted into the cast part 10. The housing contains a first hydraulic chamber 14 and a second hydraulic chamber 16. An adjustable piston 18 is inserted between the first hydraulic chamber 14 and the second hydraulic chamber 16. This piston carries an O-ring 20 and is supported by two simulator springs 22 and 24 located in the second hydraulic chamber 16. The first simulator spring 22 of the two simulator springs 22 and 24 has a significantly lower spring stiffness than the second simulator spring 24 of the two simulator springs 22 and 24. The second simulator spring 24, which contacts the cover 12, pushes a spring plate 26 away from the cover 12.The piston 18 is pushed away from the inner base surface of the spring plate 26 by means of the first simulator spring 22, which contacts an inner base surface of the spring plate 26.

[0004] Brake fluid, which is forced out of a master cylinder connected to the conventional pedal stroke simulator by the driver's braking force, can be transferred into the first hydraulic chamber 14 via a connecting bore 28 formed in the casting 10. A volume compensation opening 30 is also formed in the casting 10, through which brake fluid from the second hydraulic chamber 16 can be transferred into an attached reservoir. When a driver applies the brakes (via the master cylinder) in the conventional pedal stroke simulator, the piston 18 first moves from the first hydraulic chamber 14 into the second hydraulic chamber 16, deforming the first simulator spring 22 until the piston 18 abuts the inner surface of the spring plate 26.If, after the piston 18 has struck the inner surface of the spring plate 26, the driver continues to brake in the conventional pedal stroke simulator, piston 18 and spring plate 26 are pressed towards the sealing piston 12, deforming the second simulator spring 24. The driver can use the driver's braking force to push piston 18 into the second hydraulic chamber 16 far enough to deform an elastomer component 32 attached to the sealing cap 12. In this way, a pressure-volume characteristic curve with a large pressure rise at the end of the volume uptake should be achievable for the conventional pedal stroke simulator.

[0005] Document US 5735314 A discloses a hydraulic damper for a vehicle braking system, with a damping diaphragm on an end wall of a piston of the damper. Disclosure of the invention

[0006] The invention provides a piston for a hydraulic unit or a piston-cylinder device of a vehicle braking system with the features of claim 1, a piston-equipped assembly for a hydraulic unit or a piston-cylinder device of a vehicle braking system with the features of claim 4, a piston-cylinder device for a vehicle braking system with the features of claim 10, a hydraulic unit for a vehicle braking system with the features of claim 12, a vehicle braking system with the features of claim 13, a manufacturing method for a piston for a hydraulic unit or a piston-cylinder device of a vehicle braking system with the features of claim 14, and a manufacturing method for a piston-equipped assembly for a hydraulic unit or a piston-cylinder device of a vehicle braking system with the features of claim 15. Advantages of the invention

[0007] The present invention achieves a multifunctionality of the sealing sleeve: The sealing sleeve can be used to seal a pressure chamber volume jointly defined by the piston and the sealing sleeve. However, the sealing sleeve can also be used as a "spring element" that counteracts an increase in the pressure chamber volume. This multifunctionality of the sealing sleeve eliminates the need for, for example, an additional spring with a spring constant corresponding to the counterforce of the sealing sleeve. This reduces the manufacturing costs for a device equipped with at least the piston and the sealing sleeve. Furthermore, the multifunctionality of the sealing sleeve facilitates the miniaturization of such a device.

[0008] In an advantageous embodiment of the piston / piston-equipped assembly, the piston comprises a base section and a cylindrical section, with the contact surface being formed on the base section. The contact surface is thus relatively easy to form, for example by appropriately bending a base section stamped from sheet metal.

[0009] According to the invention, the piston with the sealing sleeve attached to it is arranged adjustably within an internal volume of the hydraulic unit or the piston-cylinder device in such a way that a partial volume of the internal volume can be limited as a pressure chamber by means of the sealing sleeve and the piston, wherein the sealing sleeve and the piston are adjustable against at least one spring force in such a way that a filling volume of the pressure chamber that can be filled with brake fluid can be increased.Accordingly, in the case of the piston-equipped assembly, the cover element can also be attached to the hydraulic unit or to the at least one housing part of the piston-cylinder device in such a way that a partial volume of the inner volume sealed on the outside by the cover element can be limited as a pressure chamber by means of the sealing sleeve and the piston, wherein the sealing sleeve and the piston are adjustable against at least one spring force of the at least one spring in such a way that a filling volume of the pressure chamber that can be filled with brake fluid can be increased.

[0010] Preferably, the at least one spring is pre-tensioned by means of the stop element pressed onto the pin. In this case, the piston-equipped assembly can not only be used as a compact insert part, but can also be tested and / or configured with respect to a desired compression characteristic before its installation in the piston-cylinder device / hydraulic unit.

[0011] Furthermore, a spring plate mounted on the pin can be supported by the piston by means of a first spring (at least one spring), and the spring plate is supported by the cover element by means of a second spring (at least one spring). As explained in more detail below, a jump-in working range can also be formed on the piston-cylinder device / hydraulic unit in this case.

[0012] In an advantageous further development, a first elastically compressible element is attached to the inside of the cover element and / or a second elastically compressible element is attached to an outer base surface of the spring plate oriented towards the piston. The first elastically compressible element buffers the transition from the jump-in working area to a subsequent working area. The second elastically compressible element ensures a high force / pressure increase at one end of a volume intake.

[0013] The advantages described above are also realized in a piston-cylinder device for a vehicle brake system with a corresponding piston or with such a piston-equipped assembly.

[0014] Preferably, the piston-cylinder device is designed as a simulator. However, the suitability of the piston-cylinder device for training purposes is not limited to simulators.

[0015] A hydraulic unit for a vehicle braking system with a corresponding piston or with such a piston-equipped assembly also has the advantages described above.

[0016] Likewise, a vehicle braking system with a corresponding piston, such a piston-equipped assembly, a corresponding piston-cylinder device or a hydraulic unit exhibits the advantages described above.

[0017] Furthermore, implementing a corresponding manufacturing process for a piston for a hydraulic unit or a piston-cylinder assembly of a vehicle brake system realizes the described advantages. Further development of the manufacturing process according to the piston embodiments described above is possible.

[0018] Furthermore, implementing a corresponding manufacturing process for a piston-equipped assembly for a hydraulic power unit or a piston-cylinder device for a vehicle brake system also yields the desired advantages. The manufacturing process can be further developed according to the embodiments of the piston-equipped assembly described above. For example, the at least one spring can be pre-tensioned by means of the stop element pressed onto the pin. Brief description of the drawings

[0019] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1. A cross-section through a state-of-the-art pedal stroke simulator; Fig. 2 a schematic representation of an embodiment of the piston-cylinder device; Fig. 3. A flowchart to explain an embodiment of the manufacturing process for a piston for a hydraulic power unit or a piston-cylinder assembly of a vehicle braking system; and Fig. 4 a flowchart to explain an embodiment of the manufacturing process for a piston-equipped assembly for a hydraulic power unit or a piston-cylinder device of a vehicle braking system. Embodiments of the invention

[0020] Fig. Figure 2 shows a schematic representation of an embodiment of the piston-cylinder device.

[0021] The in Fig. The two schematically depicted piston-cylinder devices can be used in a vehicle braking system. In particular, the piston-cylinder device can be used as a simulator / simulator device, such as a pedal simulator, pedal travel simulator, or pedal stroke simulator, within the vehicle braking system. However, it should be noted that the piston-cylinder device can also be used to perform other functions within the braking system. Furthermore, the usability of the piston-cylinder device is not limited to a specific type of braking system.

[0022] The piston-cylinder device of the Fig. 2 is designed with its own housing (consisting of at least one housing part 50). However, it should be noted that, with the exception of the at least one housing part 50, all other features of the piston-cylinder device can also be implemented in a hydraulic unit for a vehicle braking system. Likewise, at least the part equipped with these features can be used as a simulator / simulator device, such as a pedal simulator, pedal travel simulator, or pedal stroke simulator, in a variety of different vehicle braking systems. Furthermore, the usability of the hydraulic unit designed according to the piston-cylinder device is neither limited to performing a simulator function nor to a specific type of braking system.

[0023] The piston-cylinder device comprises at least one piston 52 and a sealing sleeve 54 that interacts with it. As detailed below, the sealing sleeve 54 can, for example, be attached to the (sleeve-equipped) piston 52. Likewise, the piston 52 and sealing sleeve 54 can be parts of a piston-equipped assembly. The piston 52 and sealing sleeve 54 are arranged adjacent to each other in the piston-cylinder device. Preferably, there is always physical contact between the piston 52 and the sealing sleeve 54.

[0024] Furthermore, a contact surface 56 for the sealing sleeve 54 is formed on the piston 52, which has a shape that curves away from the sealing sleeve 54. For example, a depression or a concave shape can be formed on the contact surface 56 of the piston 52 (oriented towards the sealing sleeve 54). However, the shape of the contact surface 56 that curves away from the sealing sleeve 54 can also be understood as an uneven design of the contact surface 56, e.g., the formation of at least one edge and / or at least one step on the contact surface 56. Provided that the sealing sleeve 54 exists in its initial form without any force / pressure acting upon it, the sealing sleeve 54 in its initial form and the contact surface 56 preferably surround a displacement volume 58. The displacement volume 58 can also be described as a displacement volume 58 enclosed by the contact surface 56 of the piston 52.

[0025] By means of the contact surface 56 described above, it can be ensured that the sealing sleeve 54 can be pressed at least partially into the displacement volume 58 by means of pressure (present on a side of the sealing sleeve 54 facing away from the piston 52). In particular, axially extending grooves can be formed on a side of the sealing sleeve 54 facing the piston 52, through which fluid / brake fluid can flow (almost force-free) out of the displacement volume 58. Optionally, a protruding buffer area 53 can also be formed on a piston side of the piston 52 facing the sealing sleeve 54.

[0026] The sealing sleeve 54 is therefore not only suitable for sealing a pressure chamber volume jointly limited by the piston 52 and the sealing sleeve 54, but can also be used as a "spring element" that opposes an increase in the pressure chamber volume (jointly limited by the piston 52 and the sealing sleeve 54) with a (definable) counterforce. In particular, the counterforce of the sealing sleeve 54 used as a "spring element" prevents brake fluid from being forced into the pressure chamber volume even before the piston 52 moves from its initial position. (The initial position can be defined as a position of the piston 52 in which the piston 52 is in a position without any force or pressure acting upon it.) As explained in more detail below, this multifunctionality of the sealing sleeve 54 contributes to improving the characteristic curve of the piston-cylinder device (or...a part of the hydraulic unit equipped with piston 52 and sealing sleeve 54).

[0027] In the embodiment of the Fig. 2. The piston 52 comprises a base region 52a and a cylindrical region 52b, wherein the contact surface 56 is formed on the base region 52a of the piston 52. Alternatively, however, a compact (cylindrical) piston 52 with the contact surface 56 can also be formed.

[0028] In an alternative embodiment, the sealing sleeve 54 can be attached to at least one mounting point of the piston 52. In this case, the piston 52 with the attached sealing sleeve 54 (as a single component) can be arbitrarily positioned within an internal volume 60 of the piston-cylinder assembly. Again, a partial volume 62 of the internal volume 60 can be defined as a pressure chamber 62 by means of the sealing sleeve 54 and the piston 52. For example, the sealing sleeve 54 and the bottom region 52a of the piston 52 define the pressure chamber 62, while the cylindrical region 52b of the piston 52 faces away from the pressure chamber 62. The sealing sleeve 54 also prevents brake fluid from leaking out of the pressure chamber 62 along an outer surface of the piston 52.The piston 52 and the sealing sleeve 54 can be supported in the piston-cylinder device by means of at least one spring 64 and 66 in such a way that the sealing sleeve 54 and the piston 52 can be adjusted against at least one spring force of the at least one spring 64 and 66 in such a way that the filling volume of the pressure chamber 62 that can be filled with brake fluid can be increased.

[0029] In the embodiment of the Fig. However, the piston 52 and the sealing sleeve 54 are elements of a piston-equipped assembly. The piston-equipped assembly comprises a cover element 68, a pin 70 arranged on an inner surface of the cover element 68, on which at least the sealing sleeve 54 and a piston 52 are mounted, and a stop element 72, which is attached to the pin 70 in such a way that the piston 52 or the sealing sleeve 54 is prevented from sliding off the pin 70 (by means of the stop element 72). The stop element 72 can, for example, be a stop disc 72. The piston-equipped assembly also includes at least one spring 64 and 66, by means of which the piston 52 is supported by the cover element 68. The use of such a piston-equipped assembly facilitates the manufacture of the piston-cylinder device, and thus reduces the requirements for a manufacturing system suitable for producing the piston-cylinder device.

[0030] Normally, the fill volume of the pressure chamber 62 that can be filled with brake fluid is minimal when the piston 52 is in its initial position. The piston 52 can be adjusted against the force of at least one spring 64 and 66 such that the fill volume of the pressure chamber 62 that can be filled with brake fluid can be increased. This is also frequently referred to as increasing the volume in the pressure chamber 62.

[0031] The cover element 68 can be used as a closure cover and / or as part of the housing of the piston-cylinder device. For this purpose, the cover element 68 is designed so that it can be attached to the housing part 50 of the piston-cylinder device (or to the corresponding hydraulic unit).

[0032] The internal volume 60 within the piston-cylinder assembly (or the corresponding hydraulic unit) can thus be sealed (liquid-tight) by means of the cover element 68 on an outer surface of the housing part 50 (or the hydraulic unit). The cover element 68 can be attached (liquid-tight) to the housing part 50 (or the hydraulic unit), for example, by pressing or crimping. If desired, the cover element 68, together with the housing part 50, can form the housing of the piston-cylinder assembly. (Such a cover element 68 can also be advantageously used when the piston-cylinder assembly is equipped with the (sleeve-mounted) piston 52.)

[0033] In particular, the cover element 68 can be attached to the housing part 50 of the piston-cylinder device (or the corresponding hydraulic unit) in such a way that the partial volume 62 of the inner volume 60 sealed on the outside by the cover element 68 can be limited as a pressure chamber 62 by means of the sealing sleeve 54 and the piston 52. In this case, the sealing sleeve 54 and the piston 52 are adjustable against the at least one spring force of the at least one spring 64 and 66 so that the filling volume of the pressure chamber 62 that can be filled with brake fluid can be increased.

[0034] The piston-equipped assembly of the Fig. Figure 2 shows, by way of example, a first spring 64 and a second spring 66 as the at least one spring 64 and 66. Furthermore, the piston-equipped assembly has a spring plate 74 mounted on the pin 70. (Optionally, the at least two springs 64 and 66 and the spring plate 74 can also be added when the piston-cylinder device is equipped with the (sleeve-equipped) piston 52.)

[0035] The spring plate 74 is supported by the cover element 68 by means of the first spring 64. The first spring 64 bears against the cover element 68 on one side and against an inner base surface of the spring plate 74 on a second side facing away from the cover element 68. The piston 52 is supported by the spring plate 74 by means of the second spring 66. While one side of the second spring 66 rests against the base area 52a of the piston 52, a second side of the second spring 66, facing away from the base area 52a, bears against a surface of a flange of the spring plate 74 facing away from the cover element 68. The second spring 66 extends partially through the piston interior volume of the piston 52, which is defined by the base region 52a and the cylindrical region 52b. The arrangement of the second spring 66, at least partially, within the piston interior volume allows for a reduction in the installation space required for the piston-equipped assembly.In this case, the piston-equipped assembly is also easy to install.

[0036] The first spring 64 has a lower spring stiffness than the second spring 66. Therefore, an initial movement of the piston 52 from its initial position first leads to a deformation of the first spring 64, thus simulating a jump-in operating range of the piston-cylinder assembly. The first spring 64 can therefore also be referred to as the jump-in spring. Once the spring plate 74 contacts the cover element 68, the piston 52 moves further, resulting in a deformation of the second spring 66. From this point onward, further movement of brake fluid into the pressure chamber 62 requires a greater force compared to the jump-in operating range. However, it should be noted that the design of the piston-equipped assembly is not limited to its use with exactly two springs 64 and 66.

[0037] Furthermore, the at least one spring 64 and 66 of the piston-equipped assembly, specifically the first spring 64 with the lower spring stiffness, can be pre-tensioned by means of the stop element 72 pressed onto the pin 70. In particular, a distance x1 between an end of the pin 70 pointing away from the cover element 68 and the stop element 72 can be varied to adjust a desired pre-tension of the at least one spring 64 and 66 of the piston-equipped assembly. Alternatively or additionally, a penetration depth x2 of the pin 70 into the cover element 68 can also be varied to determine the desired pre-tension of the at least one spring 64 and 66 of the piston-equipped assembly. The in Fig. The piston-equipped assembly shown in Figure 2 can thus be easily tested and / or configured with respect to a preferred characteristic curve before being installed in the piston-cylinder device. In particular, tolerances can be compensated for by varying the distance x1 and / or the penetration depth x2.

[0038] As an advantageous further development of the piston-equipped assembly, a first elastically compressible element 76 can be attached to the inside of the cover element 68, specifically to a projection formed on the inside of the cover element 68. Furthermore, the spring plate 74 can have a central indentation on its base, which projects into a volume enclosed by the spring plate 74. In this case, a protruding portion of the inner base surface of the spring plate 74 contacts the first elastically compressible element 76 when the first spring 64 is compressed.Thus, the initial movement of the piston 52 from its starting position until the spring plate 74 contacts the cover element 68 (under the deformation of the first spring 64) is counteracted by an additional "spring force" of the first elastically compressible element 76 (in addition to the first spring force of the first spring 64) from the point at which the spring plate 74 contacts the first elastically compressible element 76. This additional "spring force" of the first elastically compressible element 76 causes a "smoothing" between the jump-in working range of the piston-cylinder device (characterized by the first spring force of the first spring 64) and a subsequent working range of the piston-cylinder device (characterized by a second spring force of the second spring 66). This can also be described as a force-volume characteristic curve (or...The pressure-volume characteristic curve of the piston-cylinder device comprises an intermediate section between a jump-in section with a low slope and a further section with a higher slope, which has at least one slope between a maximum slope of the jump-in section and a minimum slope of the further section, which results from both the first spring force of the first spring 64 and the additional "spring force" of the first elastically compressible element 76.

[0039] As an alternative or supplement to the first elastically compressible element 76, a second elastically compressible element 78 can also be attached to an outer surface of the spring plate 74, particularly in the central indentation, which is oriented towards the piston 52 / its base region 52a. This ensures that (after the spring plate 74 abuts the cover element 68) the piston 52 / its base region 52a contacts the second elastically compressible element 78 when the second spring 66 is compressed. Once the piston 52 abuts the second elastically compressible element 78, an additional "spring force" of the second elastically compressible element 78 counteracts further movement of the piston 52 (in addition to the second spring force of the second spring 66). The second elastically compressible element 78 therefore creates a force-volume characteristic (or...).The pressure-volume characteristic curve of the piston-cylinder device exhibits large force values ​​(or pressure values) for a large volume in the pressure chamber 62 of the piston-cylinder device. This can also be described as the force-volume characteristic curve (or pressure-volume characteristic curve) of the piston-cylinder device having a relatively large force increase (or pressure increase) at one end of its volume intake in the pressure chamber 62.

[0040] Optionally, the first elastically compressible element 76 and the second elastically compressible element 78 can also be added when the piston-cylinder device is equipped with the (cuff-equipped) piston 52.

[0041] During operation of the piston-cylinder device, a master brake cylinder (e.g., via at least one line not shown) can be connected to the piston-cylinder device in such a way that brake fluid from the master brake cylinder can be transferred into the pressure chamber 62 via at least one connection bore 80. Likewise, a reservoir (with atmospheric pressure present therein) can be connected to the piston-cylinder device (via at least one line not shown) in such a way that brake fluid from a residual volume of the internal volume 60, separated from the pressure chamber 62 by the piston 52 and the seal 54, can be transferred into the reservoir via at least one volume exchange bore 82.(By forming several through holes / cutouts 84 at different heights of the cylindrical area 52b, an undesirable complete covering of the at least one volume exchange bore 82 can be prevented even during adjustment of the piston 52.) A driver of the vehicle equipped with the piston-cylinder device can thus, by means of his driver braking force exerted on a brake actuation element connected to the master brake cylinder, brake via the master brake cylinder and the at least one connecting bore 80 into the piston-cylinder device and cause a volume intake into the pressure chamber 62 / enlargement of the pressure chamber 62.

[0042] The functionality of the piston-cylinder device (as a simulator) will be discussed again below: Before the brake actuation element is engaged, the piston 52 is in its initial position, with the sealing sleeve 54 in its initial shape. At the beginning of the driver's braking action, the slight pressure build-up in the pressure chamber 62 causes the sealing sleeve 54 to be at least partially pressed into the displacement volume 58. The driver thus feels the slight counterforce of the sealing sleeve 54, which acts as a "spring element," but this force is still less than the initial spring force of the first spring 64. The piston-cylinder device therefore has a force-volume characteristic (or a pressure-volume characteristic) with a relatively small increase in force (pressure) at the beginning of the volume uptake in the pressure chamber 62 / the piston-cylinder device. Furthermore, since the displacement volume 58 can be moved almost without force, a force jump (pressure jump) in the force-volume characteristic curve (or the pressure-volume characteristic curve) is avoided.

[0043] Further braking by the driver into the piston-cylinder device causes the piston 52 to move, initially compressing only the first spring 64. During this process, the second spring 66 preferably remains in its (pre-tensioned) initial state. Therefore, the driver applying the brakes needs to exert comparatively little braking force to initially move the piston 52 from its starting position. The force-volume characteristic (or pressure-volume characteristic) thus exhibits a jump-in operating range.

[0044] Towards the end of the jump-in working range, the spring plate 74 contacts the first elastically compressible element 76. The further movement of the piston 52 is then counteracted by both the initial spring force of the first spring 64 and the spring force of the first elastically compressible element 76. This results in a smooth transition between the jump-in working range and the subsequent working range. The driver therefore does not perceive an abrupt change between the jump-in working range and the subsequent working range.

[0045] Only when the spring plate 74 contacts the cover element 68 does the piston 52 move further, deforming the second spring 66. Due to the second spring force of the second spring 66, which opposes the further movement of the piston 52, the driver must apply significantly more braking force to decelerate after overcoming the jump-in operating range. The driver thus experiences a standard brake feel (pedal feel) in this braking situation.

[0046] As soon as the base area 52a / piston 52 contacts the second elastically compressible element 78, further expansion of the pressure chamber 62 requires not only the deformation of the second spring 66 but also an (elastic) deformation of the second elastically compressible element 78. Therefore, to increase the volume of brake fluid that can be filled into the pressure chamber 72, the driver must overcome not only the second spring force of the second spring 66 but also the "spring force" opposing the elastic deformation of the second elastically compressible element 78 by applying their braking force. Thus, a progressive force-volume characteristic (or a progressive pressure-volume characteristic) is ensured as the pressure chamber 72 is further expanded. In particular, the piston-cylinder device has a (multi-stage progressive) force-volume characteristic (or pressure-volume characteristic) which results in a large increase in force (or pressure) for a large volume intake into the pressure chamber 62.exhibits a large pressure increase).

[0047] During the adjustment of the piston 52, the pin 70 and the stop element 72 remain stationary. Pin 70 and stop element 72 thus provide an additional sealing point for the sealing sleeve 54.

[0048] The advantages described above are also achieved in a vehicle braking system using a piston-cylinder device (or the corresponding hydraulic unit).

[0049] Fig. Figure 3 shows a flowchart to explain one embodiment of the manufacturing process for a piston for a hydraulic power unit or a piston-cylinder device of a vehicle braking system.

[0050] In process step S1, a sealing sleeve is attached to at least one mounting point of the piston. The piston can therefore be described as a sleeve-equipped piston.

[0051] In a process step S2, performed before, simultaneously, or subsequently, a contact surface for the sealing sleeve is formed on the piston with a shape that curves away from the sealing sleeve attached to the piston before or after. This ensures that, during subsequent operation of the hydraulic unit or the piston-cylinder device, the sealing sleeve is at least partially pressed into a displacement volume defined by the piston's contact surface by means of pressure (present on a side of the sealing sleeve facing away from the piston).

[0052] Fig. Figure 4 shows a flowchart to explain an embodiment of the manufacturing process for a piston-equipped assembly for a hydraulic power unit or a piston-cylinder device of a vehicle braking system.

[0053] In process step S10, a pin is positioned on the inside of a cover element. The pin can, for example, be pressed into the cover element. The cover element is suitable for attachment to the hydraulic power unit or to at least one housing part of the piston-cylinder device and for sealing an internal volume located in the hydraulic power unit or the piston-cylinder device on an outside surface of the hydraulic power unit or the piston-cylinder device (by means of the cover element). In particular, the cover element can be designed / shaped accordingly in an (optional) process step performed prior to process step S10.

[0054] In a process step S11, at least one sealing sleeve and a piston with a contact surface for the sealing sleeve having a shape curved away from the sealing sleeve are arranged on the pin, wherein the piston is supported by the cover element by means of at least one spring.

[0055] In this way, it can be ensured that during subsequent operation of the hydraulic unit or the piston-cylinder device, the sealing sleeve is at least partially pressed into a displacement volume defined by the piston's contact surface by means of pressure (present on a side of the sealing sleeve facing away from the piston). Optionally, a process step S12 can be carried out before process step S11, in which the piston is formed with the desired contact surface for the sealing sleeve.

[0056] Next, process step S13 is performed, in which a stop element is attached to the pin in such a way that the piston or sealing sleeve is prevented from sliding off the pin. For example, a retaining washer (as a stop element) can be pressed onto the pin to prevent the piston or sealing sleeve from sliding off the pin.

[0057] Optionally, the method can also include a process step S14 in which the at least one spring is pre-tensioned by means of the stop element pressed onto the pin. Alternatively or additionally, the penetration depth of the pin into the cover element can be varied to determine a desired pre-tension of the at least one spring.

Claims

[1] Piston (52) for a piston-cylinder device of a vehicle brake system, characterized by , that a sealing sleeve (54) is attached to at least one attachment point of the piston (52); and a contact surface (56) for the sealing sleeve (54) is formed on the piston (52), which has a shape curved away from the sealing sleeve (54); so that the sealing sleeve (54) can be pressed at least partially into a displacement volume (58) spanned by the contact surface (56) of the piston (52) by means of a pressure present on a side of the sealing sleeve (54) directed away from the piston (52), wherein the piston (52) with the sealing sleeve (54) attached thereto can be arranged adjustably within an internal volume (60) of the hydraulic unit or the piston-cylinder device such that a partial volume (62) of the internal volume (60) can be limited as a pressure chamber (62) by means of the sealing sleeve (54) and the piston (52), wherein the sealing sleeve (54) and the piston (52) can be adjusted against at least one spring force of at least one spring (64, 66) so that a filling volume of the pressure chamber (62) that can be filled with brake fluid can be increased. [2] Piston (52) according to claim 1, wherein the piston (52) comprises a bottom region (52a) and a cylindrical region (52b), and wherein the contact surface (56) is formed on the bottom region (52a). [3] Piston-equipped assembly for a piston-cylinder device of a vehicle brake system with a cover element (68) which can be attached to the hydraulic unit or to at least one housing part (50) of the piston-cylinder device in such a way that an internal volume (60) located in the hydraulic unit or the piston-cylinder device can be sealed on an outside of the hydraulic unit or the piston-cylinder device by means of the cover element (68); a pin (70) arranged on an inside of the lid element (68), on which at least one sealing sleeve (54) and a piston (52) are arranged, wherein a contact surface (56) for the sealing sleeve (54) is formed on the piston (52), which has a shape curved away from the sealing sleeve (54), so that the sealing sleeve (54) can be pressed at least partially into a displacement volume (58) spanned by the contact surface (56) of the piston (52) by means of a pressure present on a side of the sealing sleeve (54) directed away from the piston (52); a stop element (72) which is attached to the pin (70) in such a way that the piston (52) or the sealing sleeve (54) is prevented from sliding off the pin (70); and at least one spring (64,66) by means of which the piston (52) is supported by the cover element (68). [4] Piston-equipped assembly according to claim 3, wherein the piston (52) comprises a bottom region (52a) and a cylindrical region (52b), and wherein the contact surface (56) is formed on the bottom region (52a). [5] Piston-equipped assembly according to claim 3 or 4, wherein the cover element (68) can be attached to the hydraulic unit or to the at least one housing part (50) of the piston-cylinder device in such a way that a partial volume (62) of the inner volume (60) sealed on the outside by the cover element (68) can be limited as a pressure chamber (62) by means of the sealing sleeve (54) and the piston (52), wherein the sealing sleeve (54) and the piston (52) are adjustable against at least one spring force of the at least one spring (64, 66) so that a filling volume of the pressure chamber (62) that can be filled with brake fluid can be increased. [6] Piston-equipped assembly according to one of claims 3 to 5, wherein the at least one spring (64, 66) is pre-tensioned by means of the stop element (72) pressed onto the pin (70). [7] Piston-equipped assembly according to one of claims 3 to 6, wherein a spring plate (74) mounted on the pin (70) is supported by the piston (52) by means of a first spring (64) as the at least one spring (64, 66), and wherein the spring plate (74) is supported by the cover element (68) by means of a second spring (66) as the at least one spring (64, 66). [8] Piston-equipped assembly according to claim 7, wherein a first elastically compressible element (76) is attached to the inside of the cover element (68) and / or a second elastically compressible element (78) is attached to an outer bottom surface of the spring plate (74) oriented towards the piston (52). [9] Piston-cylinder device for a vehicle brake system comprising a piston (52) according to one of claims 1 to 2 or a piston-equipped assembly according to one of claims 3 to 8. [10] Piston-cylinder device according to claim 9, wherein the piston-cylinder device is designed as a simulator. [11] Hydraulic unit for a vehicle brake system comprising a piston (52) according to one of claims 1 to 2 or a piston-equipped assembly according to one of claims 3 to 8. [12] Vehicle brake system comprising a piston (52) according to one of claims 1 to 2, a piston-equipped assembly according to one of claims 3 to 8, a piston-cylinder device according to claim 9 or 10 or a hydraulic unit according to claim 11. [13] Manufacturing method for a piston (52) for a piston-cylinder device of a vehicle brake system according to claim 1 or 2, characterized by the steps: Attaching a sealing sleeve (54) to at least one attachment point of the piston (52) (S1); and Forming a contact surface (56) for the sealing sleeve (54) on the piston (52) with a shape (S2) curved away from the sealing sleeve (54) attached to the piston (52) before or after; so that, during subsequent operation of the hydraulic unit or the piston-cylinder device, the sealing sleeve (54) is at least partially pressed into a displacement volume (58) spanned by the contact surface (56) of the piston (52) by means of a pressure present on a side of the sealing sleeve (54) facing away from the piston (52), wherein the piston (52) with the sealing sleeve (54) attached to it is adjustably arranged within an internal volume (60) of the hydraulic unit or the piston-cylinder device such that a partial volume (62) of the internal volume (60) is limited as a pressure chamber (62) by means of the sealing sleeve (54) and the piston (52), wherein the sealing sleeve (54) and the piston (52) are adjustable against at least one spring force of at least one spring (64, 66) so that a filling volume of the pressure chamber (62) that can be filled with brake fluid can be increased is. [14] Manufacturing method for a piston-equipped assembly for a piston-cylinder device according to one of claims 3 to 8 of a vehicle brake system comprising the steps: Arranging a pin (70) on an inside of a cover element (68) for attaching to the hydraulic power unit or to at least one housing part (50) of the piston-cylinder device and for sealing an internal volume (60) located in the hydraulic power unit or the piston-cylinder device on an outside of the hydraulic power unit or the piston-cylinder device (S10); Arranging at least one sealing sleeve (54) and one piston (52) with a contact surface (56) for the sealing sleeve (54) having a shape convex away from the sealing sleeve (56) on the pin (70), wherein the piston (52) is supported by the cover element (68) by means of at least one spring (64, 66) (S11), so that the sealing sleeve (54) is pressed at least partially into a displacement volume (58) spanned by the contact surface (56) of the piston (52) by means of a pressure present on a side of the sealing sleeve (54) facing away from the piston (52); and Attaching a stop element (72) to the pin (70) in such a way as to prevent the piston (52) or the sealing sleeve (54) from sliding off the pin (70) (S13). [15] Manufacturing method according to claim 14, wherein the at least one spring (64, 66) is pre-tensioned by means of the stop element (72) pressed onto the pin (70) (S14).

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