PRIMARY PISTON FOR A MASTER BRAKE CYLINDER OR A GEARBOX

Description

[0001] The present invention relates to a primary piston for a master brake cylinder or a transmission device. The invention also relates to a master brake cylinder for a brake-by-wire braking system, a transmission device for a brake-by-wire braking system, and a brake pressure generator for a brake-by-wire braking system. State of the art

[0002] From the prior art, such as DE 10 2017 203 559 A1, a primary piston for a master brake cylinder is known which can interact with an electromechanical brake booster located upstream of the master brake cylinder. On its first side, the primary piston is supported by a primary spring projecting into a recess in the primary piston, while a force can be transmitted to a second side of the primary piston, directed away from the first side, by means of a spindle and nut of the electromechanical brake booster. Disclosure of the invention

[0003] The present invention provides a primary piston for a master brake cylinder or a transmission device with the features of claim 1, a master brake cylinder for a brake-by-wire braking system with the features of claim 5, a transmission device for a brake-by-wire braking system with the features of claim 7 and a brake pressure generator for a brake-by-wire braking system with the features of claim 10. Advantages of the invention

[0004] The present invention provides a primary piston whose advantageous shape enables a reduction in the overall length of a brake pressure generator equipped with the primary piston and combining the functions of a master brake cylinder and a transmission device. Since at least the section of the brake pressure generator's spindle oriented towards the primary piston and simultaneously at least the section of the brake pressure generator's nut oriented towards the brake piston can be inserted into and / or is inserted into the second recess of the primary piston, the compactness of the brake pressure generator equipped with the primary piston according to the invention is also increased. The reduction in the overall length of the brake pressure generator, or the increased compactness of its design, achieved by the present invention allows for a saving of installation space in a vehicle / motor vehicle constructed with it.

[0005] In an advantageous embodiment of the primary piston, at least the section of the spindle oriented towards the primary piston can be attached or secured in the second recess, while simultaneously at least the section of the nut, which is set into a rotational movement around the spindle and is oriented towards the primary piston, can be inserted into the second recess. Thus, a space created in the primary piston can be used for the spindle and nut that interact with it.

[0006] In a further advantageous embodiment of the primary piston, at least the portion of the nut oriented towards the primary piston can be secured or fastened in the second recess, while simultaneously at least the portion of the spindle, which is set in a rotational motion and oriented towards the primary piston, can be inserted into the second recess. As will become clear from the following description, in the embodiment of the primary piston described here, the cooperating nut can be (almost) completely "countersunk" into the second recess, resulting in a significant reduction in the overall length of the brake pressure generator equipped with it.

[0007] Provided that at least the portion of the nut oriented towards the primary piston is secured in the second recess, the nut can be a ball screw nut or a threaded nut. Thus, advantageous types of nuts can be used for interaction with the primary piston according to the invention.

[0008] The advantages described above are also guaranteed in a master brake cylinder for a brake-by-wire braking system with such a primary piston and the primary spring cooperating with the primary piston, wherein at least the section of the primary spring oriented towards the primary piston is fixed in the first recess of the primary piston.

[0009] Preferably, the housing of the master brake cylinder is a die casting. In this case, the housing of the master brake cylinder can be manufactured relatively inexpensively.

[0010] The advantages described above are also realized in a gearbox device for a brake-by-wire braking system with a corresponding primary piston, the spindle and the nut arranged on the spindle, which interact with the primary piston, wherein at least the section of the spindle oriented towards the primary piston or at least the section of the nut oriented towards the primary piston is fixed in the second recess of the primary piston.

[0011] As an advantageous further development, if at least the section of the spindle oriented towards the primary piston is fixed in the second recess of the primary piston, at least one torque support component can be attached to or formed on the primary piston, by means of which the primary piston is supported against an inner wall of a gearbox housing of the gearbox device. Alternatively, if at least the section of the nut oriented towards the primary piston is fixed in the second recess of the primary piston, at least one torque support component can be attached to or formed on the nut, by means of which the nut is supported against the inner wall of the gearbox housing of the gearbox device. In both cases, an undesired rotational movement of the primary piston can be prevented by means of the at least one torque support component.

[0012] Furthermore, a brake pressure generator for a brake-by-wire braking system also has the advantages explained above, which is equipped with such a primary piston, the master brake cylinder cooperating with the primary piston and its primary spring, wherein at least the portion of the primary spring oriented towards the primary piston is fixed in the first recess of the primary piston, and the gear device cooperating with the primary piston with its spindle and its nut arranged on the spindle, wherein at least the portion of the spindle oriented towards the primary piston or at least the portion of the nut oriented towards the primary piston is fixed in the second recess of the primary piston.

[0013] In an advantageous embodiment of the brake pressure generator, the housing of the master brake cylinder is a die-cast part. In this case, the housing of the master brake cylinder can be manufactured cost-effectively.

[0014] Alternatively or additionally, the master brake cylinder housing can be bolted to the gearbox housing of the transmission unit. This facilitates repair or replacement of the master brake cylinder. Brief description of the drawings

[0015] Further features and advantages of the present invention are explained below with reference to the figures. They show: Fig. 1 a schematic representation of a first embodiment of the primary piston, or of the brake pressure generator equipped therewith; and Fig. 2 a schematic representation of a second embodiment of the primary piston, or of the brake pressure generator equipped therewith. Embodiments of the invention

[0016] Fig. 1 shows a schematic representation of a first embodiment of the primary piston, or of the brake pressure generator equipped with it.

[0017] The in Fig. 1 The primary piston 10, shown schematically, is shaped on a first side 10a such that a primary spring 12 of a master brake cylinder 14 equipped with or cooperating with the primary piston 10 can mechanically contact / make contact with the primary piston 10 on the first side 10a. The primary piston 10 is shown by way of example in the embodiment of Fig. 1 The primary piston 10 is supported by a secondary piston 16 of the master cylinder 14 by means of the primary spring 12, wherein the secondary piston 16 is supported by an inner wall of the master cylinder 14 by means of a secondary spring 18. Alternatively, the primary piston 10 can also be supported by the primary spring 12 by means of an inner wall of the master cylinder 14. A first recess 20 is formed on the first side 10a of the primary piston 10, in which at least a section of the primary spring 12, aligned with the primary piston 10, can be inserted / fastened. The first side 10a of the primary piston 10 can thus be referred to as a stepped side or stepped inner contour side. The first recess 20 on the first side 10a of the primary piston 10 is preferably annular.An inner diameter of the annular first recess 20 can be less than or equal to an inner diameter of the primary spring 12, while an outer diameter of the annular first recess 20 is preferably greater than or equal to an outer diameter of the primary spring.

[0018] The primary piston 10 is also shaped on a second side 10b, facing away from the first side 10a, such that a force can be transmitted to the primary piston 10 via a spindle 22 and a nut 24 arranged on the spindle 22 of a gear unit 26 equipped with or interacting with the primary piston 10. The force can, for example, be transmitted from a motor (not shown) to the spindle 22 and the nut 24 interacting with it, and then further transmitted via the spindle 22 and the nut 24 to the primary piston 10. The motor can be a motor of the gear unit 26 or a motor externally connected to the gear unit 26. The spindle 22 and the nut 24 together form a rotary and translational gear stage of the gear unit 26.The rotary and translational gear stage formed from the spindle 22 and the nut 24 can, in particular, be the last gear stage of a power transmission chain of the gear device 26. The gear device 26 can be at least part of an electromechanical brake booster.

[0019] As in Fig. 1 As shown in the illustration, a second recess 28 is formed on the second side 10b of the primary piston 10, in which at least a section of the spindle 22 oriented towards the primary piston 10 and simultaneously at least a section of the nut 24 oriented towards the primary piston 10 can be inserted and / or fastened. The second side 10b of the primary piston 10 can therefore also be described as a stepped side or stepped inner contour side of the primary piston 10. The second recess 28 is designed to be so large that the first recess 20 formed on the first side 10a of the primary piston 10 frames at least a section of the second recess 28 oriented towards the first side 10a. This can also be described as follows: the second recess 28 of the primary piston 10 extends from the second side 10b into a piston partial volume 10c of the primary piston 10 framed by the first recess 20.By means of a cover section / piston base 10d formed on the first side 10a of the primary piston 10, the ingress of brake fluid from the master cylinder 14 into the second recess 28 of the primary piston 10 can be prevented. Preferably, the second recess 28 of the primary piston 10 extends from its second side 10b into the primary piston 10 to such an extent that the portion of the second recess 28 oriented towards the first side 10a of the primary piston 10 is separated from the first side 10a of the primary piston 10 only by means of the cover section 10d. The thickness of the cover section 10d along a maximum extension of the primary piston 10 can, for example, be less than or equal to one-tenth of the maximum extension of the primary piston 10, and in particular less than or equal to one-fifteenth of the maximum extension of the primary piston 10.

[0020] The possibility, created by the shape of the primary piston 10, of immersing at least the section of the spindle 22 oriented towards the primary piston 10 and at least the section of the nut 24 oriented towards the primary piston 10, allows the installation space of the primary piston 10 to be used for at least the sections of the spindle 22 and the nut 24. As shown in Fig. 1 As can be seen, the installation space length of the brake pressure generator, which has the functions of the brake booster 14 and the transmission device 26, can therefore be significantly reduced by means of the advantageous shape of the primary piston 10 described above.

[0021] Optionally, a rim region 10e can be formed on the first side 10a of the primary piston 10, which frames the first recess 20 of the primary piston 10. The second recess 28 on the second side 10b of the primary piston 10 can comprise an outer section 28a adjacent to the second side 10b and an inner section 28b located on a side of the outer section 28a facing away from the second side 10b. The inner section 28b of the second recess 28 can extend into the piston volume 10c framed by the first recess 20. Preferably, the maximum diameter of the inner section 28b is smaller than the minimum diameter of the outer section 28a of the second recess 28. This facilitates the formation of the inner section 28b of the second recess 28 even within the piston volume 10c of the primary piston 10 framed by the first recess 20.

[0022] In the embodiment of the Fig. 1 At least the section of the spindle 22 aligned with the primary piston 10 can be fastened / is fastened in the second recess 28. For this purpose, the maximum diameter of the inner section 28b of the second recess 28 can be (almost) equal to the maximum diameter of the section of the spindle 22 fastened in the inner section 28b. While the spindle 22 is fixed to the primary piston 10, the nut 24 can be set into rotation around the spindle 22 by operating the motor. In particular, in the embodiment of the Fig. 1 The nut 24 is mounted on a bearing 30. The spindle 22 and the primary piston attached to it are linearly adjusted by the rotational movement of the nut 24, whereby the second recess 28 / its outer section 28a of the adjusted primary piston 10 receives or releases the portion of the rotating nut 24 aligned with the primary piston 10. Therefore, preferably the minimum diameter of the outer section 28a of the second recess 28 is larger than the maximum diameter of the portion of the nut 24 that can be inserted into the outer section 28a.

[0023] As an advantageous further development, in the embodiment of the Fig. 1 At least one torque support component 32 is attached to or formed on the primary piston 10. By means of the at least one torque support component 32, the primary piston 10 can be supported on an inner wall of a gearbox housing 34 of the gearbox device 26 in such a way that an undesired co-rotational movement of the primary piston 10 together with the nut 24 set in its rotational movement is prevented.

[0024] Regarding further features of the brake pressure generator of the Fig. 1 and their advantages are described below.

[0025] Fig. 2 shows a schematic representation of a second embodiment of the primary piston, or of the brake pressure generator equipped with it.

[0026] In contrast to the embodiment described above, in the primary piston 10 the Fig. 2 At least the portion of the nut 24 oriented towards the primary piston 10 can be fastened / is fastened in the second recess 28 / its outer section 28a. Preferably, the maximum diameter of the outer section 28a of the second recess 28 is (essentially) equal to the maximum diameter of the portion of the nut 24 fastened in the second recess 28 / its outer section 28a. While the nut 24 is fixed to the primary piston 10, the spindle 22 can be set into rotation about a longitudinal axis of the spindle 22 relative to the primary piston 10 by operating the motor. At least the portion of the spindle 22 oriented towards the primary piston 10, set into rotation, rotates into or out of the second recess 28 / its inner section 28b during the rotation.Preferably, therefore, the minimum diameter of the inner section 28b of the second recess 28 is larger than the maximum diameter of the section of the spindle 22 that can be inserted into the inner section 28b. To support the axial force, the spindle 22 can be supported by a bearing 36.

[0027] As a comparison of the Fig. 1 and 2 as can be seen, in the embodiment of the Fig. 1 The spindle 22 extends into the second recess 28 up to the cover section 10d. A maximum stroke of spindle 22 and nut 24 can therefore be completely accommodated within the installation space of the primary piston 10. Therefore, the brake pressure generator of the Fig. 2 a shorter overall length than the embodiment of Fig. 1 on. At the brake pressure generator of the Fig. 2 The compactness of its design is thus further optimized.

[0028] As an advantageous further development, the following is attached to the mother 24 of the brake pressure generator. Fig. 2 At least one torque support component 38 is attached / formed, by means of which the nut 24 and thus also the primary piston 10 are supported on the inner wall of the gearbox housing 34 of the gearbox device 26. An undesired co-rotation of the primary piston 10 together with the spindle 22 set in its rotational movement is therefore also prevented in the brake pressure generator of the Fig. 2 prevented.

[0029] Regarding further features and characteristics of the brake pressure generator of the Fig. 2 Reference is made to the description of the embodiment of the Fig. 1 and the following explanations are referred to.

[0030] All the brake pressure generators described above can be used for a brake-by-wire braking system, a servo brake, or a power brake. However, the applicability of the brake pressure generators described above is not limited to the applications listed here.

[0031] In each of the brake pressure generators described above, its nut 24 can also be referred to as a spindle nut. The nut 24 can be, for example, a ball screw nut or a threaded nut. The spindle 22 can be a threaded spindle, a ball screw, or a rack.

[0032] A housing 40 of the master brake cylinder 14 can be screwed to the gearbox housing 34 of the gearbox assembly 26 by means of at least one screw 42. This facilitates the mounting of the master brake cylinder 14 to the gearbox assembly 26 and allows for quick and easy replacement of the master brake cylinder 14 in the event of servicing. Furthermore, in this case, the master brake cylinder 14 can be manufactured as a separate assembly, independent of the gearbox assembly 26. Preferably, the housing 40 of the master brake cylinder 14 is a die casting, in particular a die casting made of aluminum. In this case, the master brake cylinder 14 can be manufactured relatively inexpensively.

[0033] All brake pressure generators described above can be used to implement a dual-circuit brake system. However, it should be noted that the master brake cylinder 14 of the brake pressure generators described above is only designed as an example of a tandem master brake cylinder. Alternatively, the master brake cylinder 14 can also be configured for the hydraulic connection of only a single brake circuit.

[0034] It is reiterated that all the brake pressure generators described above have a compact design and are cost-effective to manufacture. Due to the advantageous use of the installation space of their primary piston 10, the unwanted protrusion of their spindle 22 into the passenger compartment of the vehicle equipped with them is not a problem.

Claims

1. Primary piston (10) for a master brake cylinder (14) or a transmission device (26), which has on a first side (10a) a first depression (20) into which at least one sub-portion, oriented towards the primary piston (10), of a primary spring (12) of a master brake cylinder (14) equipped with or interacting with the primary piston (10) is able to be introduced or is fastened, wherein, on a second side (10b), directed away from the first side (10a), of the primary piston (10), there is formed a second depression (28) into which at least one sub-portion, oriented towards the primary piston (10), of a spindle (22) of a transmission device (26) equipped with or interacting with the primary piston (10), and at the same time at least one sub-portion, oriented towards the primary piston (10), of a nut (24) of the transmission device (26) arranged on the spindle (22), is able to be introduced and / or is fastened, characterized in that the first depression (20) formed on the first side (10a) of the primary piston (10) surrounds at least one sub-portion, oriented towards the first side (10a), of the second depression (28).

2. Primary piston (10) according to Claim 1, wherein at least that sub-portion of the spindle (22) which is oriented towards the primary piston (10) is able to be or is fastened in the second depression (28), while at the same time at least that sub-portion of the nut (24) which is oriented towards the primary piston (10), said nut being set in rotational motion around the spindle (22), is able to be introduced into the second depression (28).

3. Primary piston (10) according to Claim 1, wherein at least that sub-portion of the nut (24) which is oriented towards the primary piston (10) is able to be or is fastened in the second depression (28), while at the same time at least that sub-portion of the spindle (22) which is oriented towards the primary piston (10), said spindle being set in rotational motion, is able to be introduced into the second depression (28).

4. Primary piston (10) according to Claim 3, wherein at least that sub-portion of the nut (24) which is oriented towards the primary piston (10) is fastened in the second depression (28), and the nut (24) is a recirculating ball nut or a threaded nut.

5. Master brake cylinder (14) for a brake-by-wire brake system, having: a primary piston (10) according to one of the preceding claims, and the primary spring (12) that interacts with the primary piston (10), wherein at least that sub-portion of the primary spring (12) which is oriented towards the primary piston (10) is fastened in the first depression (20) of the primary piston (10).

6. Master brake cylinder (14) according to Claim 5, wherein a housing (40) of the master brake cylinder (14) is a permanent mould casting.

7. Transmission device (26) for a brake-by-wire brake system, having: a primary piston (10) according to one of Claims 1 to 4, and the spindle (22) and the nut (24) arranged on the spindle (22) that interact with the primary piston (10), wherein at least that sub-portion of the spindle (22) which is oriented towards the primary piston (10) or at least that sub-portion of the nut (24) which is oriented towards the primary piston (10) is fastened in the second depression (28) of the primary piston (10).

8. Transmission device (26) according to Claim 7, wherein at least that sub-portion of the spindle (22) which is oriented towards the primary piston (10) is fastened in the second depression (28) of the primary piston (10), and wherein at least one torque support component (32) is fastened to or formed on the primary piston (10), by means of which at least one torque support component the primary piston (10) is supported against an inner wall of a transmission housing (34) of the transmission device (26).

9. Transmission device (26) according to Claim 7, wherein at least that sub-portion of the nut (24) which is oriented towards the primary piston (10) is fastened in the second depression (28) of the primary piston (10), and wherein at least one torque support component (38) is fastened to or formed on the nut (24), by means of which at least one torque support component the nut (24) is supported against the inner wall of the transmission housing (34) of the transmission device (26).

10. Brake pressure generator for a brake-by-wire brake system, having: a primary piston (10) according to one of Claims 1 to 4, the master brake cylinder (14) interacting with the primary piston (10) and its primary spring (12), wherein at least that sub-portion of the primary spring (12) which is oriented towards the primary piston (10) is fastened in the first depression (20) of the primary piston (10), and the transmission device (26) interacting with the primary piston (10), with its spindle (22) and its nut (24) arranged on the spindle (22), wherein at least that sub-portion of the spindle (22) which is oriented towards the primary piston (10) or at least that sub-portion of the nut (24) which is oriented towards the primary piston (10) is fastened in the second depression (28) of the primary piston (10).

11. Brake pressure generator according to Claim 10, wherein a housing (40) of the master brake cylinder (14) is a permanent mould casting.

12. Brake pressure generator according to Claim 10 or 11, wherein the housing (40) of the master brake cylinder (14) is fixedly screwed to the transmission housing (34) of the transmission device (26).