Primary piston for master brake cylinder or transmission

Abstract

The invention relates to a main piston (10) for a master brake cylinder (14) or a transmission (26), which has, on a first side (10a), a first recess (20) into which at least a sub-section of a main spring (12) of the master brake cylinder (14), which is provided with the main piston (10) or interacts with the main piston (10), which sub-section is oriented towards the main piston (10), is fixed or can be introduced, a second recess (28) is formed on a second side (10b) of the main piston (10) facing away from the first side (10a), at least a sub-section of the main shaft (22), which is provided with the main piston (10) or a transmission (26) interacting with the main piston (10), which is oriented towards the main piston (10), and at the same time at least a sub-section of a nut (24) of the transmission (26), which is arranged on the main shaft (22), which is oriented towards the main piston (10), are fixed / insertable into the second recess, and wherein the nut (24) is inserted into the second recess, a first recess (20) formed on the first side (10a) of the main piston (10) surrounds at least a sub-section of the second recess (28) oriented towards the first side (10a).

Description

Technical Field

[0001] The invention relates to a master 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. Background Art

[0002] According to the prior art, for example, patent document DE 10 2017 203 559 A1, a master piston for a master brake cylinder is known, which can interact with an electromechanical brake booster located upstream of the master brake cylinder. The master piston is supported on its first side by a main spring protruding into a recess of the master piston, while the force should be transferable via the spindle and nut of the electromechanical brake booster to a second side of the master piston pointing away from the first side. Summary of the invention

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

[0004] Advantages of the present invention

[0005] The 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. Since at least a subsection of the main shaft of the brake pressure generator oriented toward the primary piston and at the same time at least a subsection of the nut of the brake pressure generator oriented toward the primary piston are introduced and / or can be introduced 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. Due to the reduction in the overall length of the brake pressure generator brought about by the invention, or the increase in its compactness, the overall space of the vehicle / motor vehicle equipped with the brake pressure generator can be saved.

[0006] In an advantageous embodiment of the main piston, at least the subsection of the spindle oriented toward the main piston is fixed or can be fixed in the second recess, while at the same time at least the subsection of the nut which is in a rotational movement about the spindle oriented toward the main piston can be introduced into the second recess. Thus, the structural space provided in the main piston can be used for the spindle and the nut which interact therewith.

[0007] In another advantageous embodiment of the primary piston, at least the subsection of the nut oriented toward the primary piston is fixed or can be fixed in the second recess, while at the same time, at least the subsection of the main shaft in rotational motion oriented toward the primary piston can be introduced into the second recess. As is clear from the following description, in the embodiment of the primary piston described here, the nut interacting with the primary piston can be (almost) completely "sunk" into the second recess, which leads to a significant reduction in the overall length of the brake pressure generator equipped with the primary piston.

[0008] If at least the subsection of the nut oriented toward the primary piston is fixed in the second recess, the nut can be a recirculating ball nut or a threaded nut. Thus, an advantageous type of nut can be used to interact with the primary piston according to the invention.

[0009] The above advantages are also ensured in a master brake cylinder for a brake-by-wire brake system, which has such a master piston and a main spring interacting with the master piston, wherein at least a subsection of the main spring oriented toward the master piston is fixed in a first recess of the master piston.

[0010] Preferably, the housing of the master brake cylinder is a metal die casting (Kokillenguss, ie permanent die casting). In this case, the housing of the master brake cylinder can be manufactured relatively cost-effectively.

[0011] The above advantages can also be achieved in a transmission device for a wire-controlled brake system, which has a corresponding main piston, a main shaft and a nut arranged on the main shaft, which interacts with the main piston, wherein at least a subsection of the main shaft oriented toward the main piston or at least a subsection of the nut oriented toward the main piston is fixed in a second recess of the main piston.

[0012] As an advantageous improvement, if at least the subsection of the main shaft oriented toward the main piston is fixed in the second recess of the main piston, at least one torque support component is fixed or formed on the main piston, by which the main piston is supported on the inner wall of the transmission housing of the transmission. Alternatively, if at least the subsection of the nut oriented toward the main piston is fixed in the second recess of the main piston, at least one torque support component is fixed or formed on the nut, by which the nut is supported on the inner wall of the transmission housing of the transmission. In both cases, undesired co-rotational movements of the main piston can be prevented by means of at least one torque support component.

[0013] In addition, a brake pressure generator for a brake-by-wire brake system also has the above-mentioned advantages, and is equipped with: such a main piston; a main brake cylinder interacting with the main piston and a main spring of the main brake cylinder, wherein at least a subsection of the main spring oriented toward the main piston is fixed in a first recess of the main piston; and a transmission device interacting with the main piston, the transmission device having a main shaft and a nut arranged on the main shaft, wherein at least a subsection of the main shaft oriented toward the main piston or at least a subsection of the nut oriented toward the main piston is fixed in a second recess of the main piston.

[0014] In an advantageous embodiment of the brake pressure generator, the housing of the master brake cylinder is a metal die casting. In this case, the housing of the master brake cylinder can be manufactured cost-effectively.

[0015] Alternatively or additionally, the housing of the master brake cylinder can be fixed to the transmission housing of the transmission with a screw. This makes it easy to repair or replace the master brake cylinder. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Other features and advantages of the present invention are explained below with reference to the accompanying drawings, wherein:

[0017] Figure 1 A schematic diagram showing a first embodiment of a primary piston or a brake pressure generator equipped with the primary piston; and

[0018] Figure 2 A schematic diagram of a second specific embodiment of a primary piston or a brake pressure generator equipped with the primary piston is shown. DETAILED DESCRIPTION

[0019] Figure 1 A schematic diagram of a first specific embodiment of a primary piston or a brake pressure generator equipped with the primary piston is shown.

[0020] Figure 1 The primary piston 10 schematically shown in FIG. 1 is shaped on a first side 10 a so that a primary spring 12 of a master brake cylinder 14 equipped with the primary piston 10 or interacting with the primary piston 10 mechanically contacts / can contact the primary piston 10 on a first side 10 a. For example, Figure 1In the embodiment of the present invention, the primary piston 10 is supported / can be supported by the secondary piston 16 of the master brake cylinder 14 through the primary spring 12, wherein the secondary piston 16 is supported / can be supported by the inner wall of the master brake cylinder 14 through the secondary spring 18. However, alternatively, the primary piston 10 can also be supported / can be supported by the inner wall of the master brake cylinder 14 through the primary spring 12. A first recess 20 is formed on the first side 10a of the primary piston 10, in which at least a subsection of the main spring 12 oriented toward the primary piston 10 is fixed / can be introduced. The first side 10a of the primary piston 10 can therefore be referred to as a stepped side or a stepped inner contour side. The first recess 20 on the first side 10a of the primary piston 10 is preferably configured in an annular shape. The inner diameter of the first recess 20 of the annular structure can be less than or equal to the inner diameter of the main spring 12, and the outer diameter of the first recess 20 of the annular structure is preferably greater than or equal to the outer diameter of the main spring 12.

[0021] The primary piston 10 is also formed on a second side 10b pointing away from the first side 10a so that via a spindle 22 equipped with the primary piston 10 or a transmission 26 interacting with the primary piston 10 and a nut 24 arranged at the spindle 22, forces are transmitted / transmittable to the primary piston 10. For example, forces can be transmitted from a motor (not shown) to the spindle 22 and the nut 24 interacting with the spindle and then further transmitted to the primary piston 10 via the spindle 22 and the nut 24. The motor can be a motor of the transmission 26 or an external motor connected to the transmission 26. The spindle 22 and the nut 24 together form a rotational and translational transmission stage of the transmission 26. The rotational and translational transmission stage formed by the spindle 22 and the nut 24 can in particular be the last transmission stage of the force transmission chain of the transmission 26. The transmission 26 can at least be part of an electromechanical brake booster.

[0022] like Figure 1As shown, a second recess 28 is formed on the second side 10b of the primary piston 10, in which at least a subsection of the spindle 22 oriented toward the primary piston 10 and at the same time at least a subsection of the nut 24 oriented toward the primary piston 10 is fixed / can be introduced. Therefore, the second side 10b of the primary piston 10 can also be described as a stepped side or stepped inner contour side of the primary piston 10. The volume size of the second recess 28 is configured so that the first recess 20 formed on the first side 10a of the primary piston 10 at least surrounds the subsection of the second recess 28 oriented toward the first side 10a. This can also be described as the second recess 28 of the primary piston 10 extending from the second side 10b to the piston subvolume 10c of the primary piston 10 surrounded by the first recess 20. By the cover section / piston top 10d of the piston subvolume 10c formed on the first side 10a of the primary piston 10, the brake fluid can be prevented from penetrating from the master brake cylinder 14 into the second recess 28 of the primary piston 10. Preferably, the second recess 28 of the primary piston 10 extends from its second side 10b so far into the primary piston 10 that a subsection of the second recess 28 oriented toward the first side 10a of the primary piston 10 is separated from the first side 10a of the primary piston 10 only by the cover section 10d. The thickness of the cover section 10d along the maximum extension of the primary piston 10 can be, for example, less than or equal to one tenth of the maximum extension of the primary piston 10, in particular less than or equal to one fifteenth of the maximum extension of the primary piston 10.

[0023] By the possibility of sinking at least the subsection of the spindle 22 oriented toward the main piston 10 and at least the subsection of the nut 24 oriented toward the main piston 10 due to the shape of the main piston 10, the structural space of the main piston 10 can be used at least for the subsections of the spindle 22 and the nut 24. Figure 1 It can be seen in FIG. 1 that the installation space length of the brake pressure generator having the functions of brake booster 14 and transmission 26 can thus be significantly reduced by the above-described advantageous shape of primary piston 10 .

[0024] Optionally, an edge region 10e may also be formed on the first side 10a of the primary piston 10, which surrounds the first recess 20 of the primary piston 10. The second recess 28 on the second side 10b of the primary piston 10 may include an outer section 28a adjacent to the second side 10b and an inner section 28b located on the side of the outer section 28a pointing away from the second side 10b. The inner section 28b of the second recess 28 may extend into the piston subvolume 10c surrounded by the first recess 20. Preferably, the maximum diameter of the inner section 28b of the second recess 28 is smaller than the minimum diameter of the outer section 28a. This makes it easy to construct the inner section 28b of the second recess 28 in the piston subvolume 10c of the primary piston 10 surrounded by the first recess 20.

[0025] exist Figure 1In the embodiment, at least the subsection of the main shaft 22 oriented toward the main piston 10 is fixed / can be fixed 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 subsection of the main shaft 22 fixed in the inner section 28b. When the main shaft 22 is fixed to the main piston 10, the nut 24 can be driven to perform a rotational movement around the main shaft 22 by the operation of the motor. Specifically, in Figure 1 In the embodiment of the present invention, the nut 24 is supported by the bearing 30. By the rotational movement of the nut 24, the main shaft 22 and the main piston fixed thereto are linearly adjusted, wherein the second recess 28 / the outer section 28a of the adjusted main piston 10 receives or releases the subsection of the rotating nut 24 oriented toward the main piston 10. Preferably, the smallest diameter of the outer section 28a of the second recess 28 is therefore greater than the maximum diameter of the subsection of the nut 24 that can be introduced into the outer section 28a.

[0026] As a favorable improvement, Figure 1 In the embodiment of the present invention, at least one torque support component 32 is also fixed or formed on the main piston 10. By means of the at least one torque support component 32, the main piston 10 can be supported on the inner wall of the transmission housing 34 of the transmission 26, thereby preventing an undesired common rotational movement of the main piston 10 with the nut 24 during its rotational movement.

[0027] about Figure 1 For other features and advantages of the brake pressure generator, refer to the following description.

[0028] Figure 2 A schematic diagram of a second specific embodiment of a primary piston or a brake pressure generator equipped with the primary piston is shown.

[0029] Unlike the previously described embodiments, Figure 2In the main piston 10 of the present invention, at least the subsection of the nut 24 oriented toward the main piston 10 is fixed / can be fixed in the second recess 28 / its outer section 28a. For this purpose, preferably, the maximum diameter of the outer section 28a of the second recess 28 is (substantially) equal to the maximum diameter of the subsection of the nut 24 fixed in the second recess 28 / its outer section 28a. When the nut 24 is fixed to the main piston 10, the main shaft 22 can be stimulated by the operation of the motor to perform a rotational movement about the longitudinal axis of the main shaft 22 relative to the main piston 10. During the rotational movement, at least the subsection of the main shaft 22 oriented toward the main piston 10 in the rotational movement rotates into the second recess 28 / its inner section 28b or rotates out of the second recess 28 / its inner section 28b. Preferably, the minimum diameter of the inner section 28b of the second recess 28 is therefore greater than the maximum diameter of the subsection of the main shaft 22 that can be introduced into the inner section 28b. In order to support axial forces, the main shaft 22 can be supported by the support 36.

[0030] from Figure 1 and Figure 2 The comparison shows that in Figure 1 In the embodiment of the present invention, the spindle 22 can be sunk into the second recess 28 up to the cover section 10d. Therefore, the maximum stroke of the spindle 22 and the nut 24 can be completely accommodated in the structural space of the main piston 10. Therefore, Figure 2 The brake pressure generator has a ratio Figure 1 The embodiment with a shorter overall length. Figure 2 The compactness of the brake pressure generator is thus further optimized.

[0031] As a favorable improvement, Figure 2 At least one torque support component 38 is also fixed / formed at the nut 24 of the brake pressure generator, by which the nut and thus the primary piston 10 are supported at the inner wall of the transmission housing 34 of the transmission 26. Figure 2 In the case of a brake pressure generator, an undesired joint rotational movement of the primary piston 10 together with the main shaft 22 which is in its rotational movement is also prevented.

[0032] about Figure 2 For other features and characteristics of the brake pressure generator, refer to Figure 1 Description and following explanation of embodiments of the present invention.

[0033] All of the above brake pressure generators can be used in brake-by-wire braking systems, servo brakes or power brakes. However, the usability of the above brake pressure generators is not limited to the uses listed here.

[0034] For each of the above-mentioned brake pressure generators, its nut 24 can also be referred to as a spindle nut. The nut 24 can be, for example, a recirculating ball nut or a threaded nut. The spindle 22 can be understood as a threaded spindle, a recirculating ball spindle or a rack.

[0035] The housing 40 of the master brake cylinder 14 can be screwed to the transmission housing 34 of the transmission 26 by means of at least one screw 42. This makes it easier to assemble the master brake cylinder 14 on the transmission 26 and enables the master brake cylinder 14 to be replaced quickly and easily in the event of maintenance. In this case, the master brake cylinder 14 can also be manufactured as a separate component from the transmission 26. Preferably, the housing 40 of the master brake cylinder 14 is a metal die casting, for example, in particular made of aluminum. In this case, the master brake cylinder 14 can be manufactured relatively cost-effectively.

[0036] All of the above-mentioned brake pressure generators can be used to implement a dual-circuit brake system. However, it should be noted that the master brake cylinder 14 of the above-mentioned brake pressure generator is only exemplarily configured as a tandem master brake cylinder. Alternatively, the master brake cylinder 14 can also be configured as a hydraulic connection for only a single brake circuit.

[0037] It should be noted again that all of the above-described brake pressure generators have a compact structure and can be manufactured cost-effectively. Due to the advantageous use of the structural space of their primary piston 10, it is not necessary to tolerate undesirable protrusion of their main shaft 22 into the passenger compartment of the vehicle equipped with the brake pressure generator.

Claims

1. A master piston (10) for a master brake cylinder (14) or a transmission (26), The master piston has a first recess (20) on a first side (10a), into which at least a subsection of a main spring (12) of a master brake cylinder (14) equipped with the master piston (10) or interacting with the master piston (10) and oriented toward the master piston (10) is fixed / can be introduced, It is characterized in that A second recess (28) is formed on a second side (10b) of the main piston (10) pointing away from the first side (10a), in which at least a subsection of a main shaft (22) of a transmission device (26) that is equipped with the main piston (10) or that interacts with the main piston (10) and that is oriented toward the main piston (10) and at the same time at least a subsection of a nut (24) of the transmission device (26) that is arranged on the main shaft (22) and that is oriented toward the main piston (10) is fixed / can be introduced into the second recess (28), A first recess (20) formed on a first side (10a) of the main piston (10) surrounds at least a subsection of the second recess (28) oriented toward the first side (10a).

2. The main piston (10) according to claim 1, wherein: At least a subsection of the spindle (22) oriented toward the main piston (10) is fixed / can be fixed in the second recess (28), while at the same time at least a subsection of the nut (24) oriented toward the main piston (10) which is in rotational motion about the spindle (22) can be introduced into the second recess (28).

3. The main piston (10) according to claim 1, wherein: At least a subsection of the nut (24) oriented toward the main piston (10) is fixed or can be fixed in the second recess (28), while at the same time at least a subsection of the main shaft (22) in rotational motion oriented toward the main piston (10) can be introduced into the second recess (28).

4. The main piston (10) according to claim 3, characterized in that At least a subsection of the nut (24) oriented toward the main piston (10) is fixed in the second recess (28), and the nut (24) is a recirculating ball nut or a threaded nut.

5. A master brake cylinder (14) for a brake-by-wire braking system, the master brake cylinder comprising: A primary piston (10) according to any one of the preceding claims; and a main spring (12) interacting with the main piston (10), in, At least a subsection of the main spring (12) oriented toward the main piston (10) is fixed in a first recess (20) of the main piston (10).

6. The master brake cylinder (14) according to claim 5, wherein: The housing (40) of the master brake cylinder (14) is a metal die casting.

7. A transmission device (26) for a brake-by-wire braking system, the transmission device comprising: A main piston (10) according to any one of claims 1 to 4; and a main shaft (22) and a nut (24) arranged on the main shaft (22), the nut interacting with the main piston (10), in, At least a subsection of the spindle (22) oriented toward the primary piston (10) or at least a subsection of the nut (24) oriented toward the primary piston (10) is fixed in a second recess (28) of the primary piston (10).

8. The transmission device (26) according to claim 7, wherein: At least a subsection of the main shaft (22) oriented toward the main piston (10) is fixed in a second recess (28) of the main piston (10), and at least one torque support component (32) is fixed or formed on the main piston (10), by which the main piston (10) is supported on the inner wall of a transmission housing (34) of the transmission (26).

9. The transmission device (26) according to claim 7, wherein: At least a subsection of the nut (24) oriented toward the primary piston (10) is fixed in a second recess (28) of the primary piston (10), and at least one torque support component (38) is fixed or formed on the nut (24), by which the nut (24) is supported on an inner wall of a transmission housing (34) of the transmission (26).

10. A brake pressure generator for a brake-by-wire braking system, the brake pressure generator comprising: A main piston (10) according to any one of claims 1 to 4; A master brake cylinder (14) interacting with the master piston (10) and a master spring (12) of the master brake cylinder, wherein: At least a subsection of the main spring (12) oriented toward the main piston (10) is fixed in a first recess (20) of the main piston (10); and A transmission device (26) interacting with the main piston (10), the transmission device having a main shaft (22) and a nut (24) arranged on the main shaft (22), wherein at least a subsection of the main shaft (22) oriented toward the main piston (10) or at least a subsection of the nut (24) oriented toward the main piston (10) is fixed in a second recess (28) of the main piston (10).

11. The brake pressure generator according to claim 10, wherein: The housing (40) of the master brake cylinder (14) is a metal die casting.

12. The brake pressure generator according to claim 10 or 11, wherein: The housing (40) of the master brake cylinder (14) is fastened to the transmission housing (34) of the transmission (26) by means of screws.

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