Electromechanical drive brake pressure generator for a hydraulic brake system of a vehicle and vehicle comprising same

Abstract

The present invention relates to an electromechanically driven brake pressure generator for a hydraulic braking system of a vehicle, comprising an electric motor unit (1) operable by an electronic control unit (2) according to the brake pressure to be applied, and a reduction gear unit (3) having a spindle drive unit (4) on the output side converting the rotational motion (a) generated by the electric motor unit into translational motion (b) to manipulate the piston (9) of a hydraulic piston / cylinder unit (5), wherein the hydraulic block (6) of the piston / cylinder unit (5) also at least partially accommodates the electric motor unit (1) such that the motor shaft (7) of the electric motor unit (1), which extends at least primarily in the region of the hydraulic block (6), is axially parallel to the longitudinal axis (8) of the piston (9) of the piston / cylinder unit (5) which is movable in the hydraulic block (6).

Description

Technical Field

[0001] This invention relates to an electromechanically driven brake pressure generator for a vehicle's hydraulic braking system, and a vehicle including the electromechanical brake pressure generator. The electromechanical brake pressure generator is equipped with an electric motor unit that can be operated by an electronic control unit according to the applied brake pressure. A reduction gear transmission unit with an output-side spindle drive unit converts the resulting rotational motion of the electric motor unit into translational motion to manipulate the piston of a hydraulic piston / cylinder unit.

[0002] The future drive concept for motor vehicles requires alternative braking force accumulation devices because low pressure no longer provides the necessary power to drive conventional vacuum brake boosters. Therefore, an electromechanical brake pressure generator of interest is being developed here.

[0003] In the electromechanically driven brake pressure generators of the type of concern here, braking pressure is generated at the piston / cylinder unit by means of an electric motor or other suitable electric actuator. Such brake pressure generators can be used not only to provide auxiliary force but also to generate braking force independently in so-called brake-by-wire systems. Therefore, electromechanical brake pressure generators are particularly advantageous in autonomous driving applications. Background Technology

[0004] According to known prior art for such electromechanical brake pressure generators, when the brake pedal is operated, the input lever moves relative to the piston of the hydraulic brake cylinder unit. This travel difference is measured by an electronic pedal travel sensor and transmitted to an electronic control unit. The control unit calculates the corresponding control signal for the electric drive motor. The motor torque is converted into a supporting force for the driver via a multi-stage gear transmission. The force provided by this amplifier is converted into hydraulic pressure for braking in the hydraulic piston / cylinder unit. Here, the electromechanical brake pressure generator provides a braking feel similar to that of a conventional vacuum brake force generator. Therefore, this braking feel can be adapted to the vehicle's brand-specific characteristics via software through the electronic control unit.

[0005] According to WO 2017 / 045804 A1, there is an electromechanical brake pressure generator of this class. The brake pressure generator includes an electric drive motor connected to a spindle drive unit via a multi-stage spur gear transmission, such that rotation of the electric drive motor causes translational motion of the spindle of the spindle drive unit to operate the master brake cylinder. However, when the reduction ratio is relatively low, the multi-stage spur gear transmission produces a considerable radial gap relative to the spindle drive unit, resulting in a considerably large overall structure for this electromechanical brake pressure generator. Summary of the Invention

[0006] The objective of this invention is to realize an electromechanical braking pressure generator, which is characterized by a space-saving structure with short electrical and mechanical connection strokes.

[0007] The present invention includes the following technical teaching: in the sense of a common housing, the hydraulic block of the piston / cylinder unit also accommodates the electric motor unit at least partially such that the motor shaft of the electric motor unit, which extends at least primarily in the region of the hydraulic block, is arranged axially parallel to the longitudinal axis of the piston of the piston / cylinder unit, which is capable of axial movement in the hydraulic block.

[0008] The advantage of the solution according to the invention lies particularly in the complete elimination of a separate housing for the electric motor unit. This is because the hydraulic block forms not only the housing environment for the piston / cylinder unit but also the housing environment for the electric motor unit. This enables a compact design of the entire electromechanical brake pressure generator, particularly in the axial direction. Compared to the externally located electric motor units of the prior art, the electric motor unit integrated into the hydraulic block according to the invention benefits from an improved thermal attachment structure with the hydraulic block, which has a considerably high thermal mass, thus improving the cooling of the electric motor unit relative to the prior art by increasing heat dissipation.

[0009] According to a preferred embodiment, a functionally integrated hydraulic block according to the invention is manufactured from a light metal alloy, particularly an aluminum alloy, and given a cuboid envelope geometry. The cuboid envelope geometry is understood to be the general basic geometry of the hydraulic block, which can also have radii, grooves, moldings, and the like. The chosen light metal alloy promotes the desired high heat dissipation due to the material's high thermal conductivity.

[0010] According to an improvement to the invention, the dimensions of the hydraulic borehole in the hydraulic block, i.e., the cylinder space and the dimensions of the internal channel guide, are determined in a manner that meets the cooling requirements of the electric motor unit. This means that the channel extends as close as possible to the electric motor unit to optimize heat dissipation.

[0011] According to a preferred embodiment of the invention, the hydraulic block, preferably rectangular in shape, has a first end side, at which the transmission unit is directly disposed. The transmission unit is preferably constructed as a multi-stage spur gear transmission, bridging the wheelbase X between the electric motor unit and a spindle transmission unit arranged coaxially with the piston / cylinder unit. This results in a transmission unit constructed to be fairly flat, which only slightly increases the geometry of the electromechanical brake pressure generator in the axial direction. In principle, this configuration achieves an approximately U-shaped energy flow from the electric motor unit to the piston / cylinder unit, which forms the basic structural scheme for the compact structure according to the invention.

[0012] By improving cooling according to the invention and reducing energy loss through a compact structure, a smaller electric motor unit can be used compared to the prior art. Furthermore, the reduced heating of the electric motor unit, resulting in a lower motor shaft operating temperature, also makes it possible to use gears made of plastic to construct multi-stage spur gear drives. This allows for the more efficient manufacture of lighter drive units compared to the prior art.

[0013] Furthermore, integrating the electric drive motor into a rigid hydraulic block results in a short tolerance chain between the electric drive unit and the transmission unit, thereby enabling optimized gear meshing in a simple manner. In addition, this is accompanied by improved vibration characteristics, especially NVH characteristics (NVH = Noise, Vibration, Harshness), thus avoiding perceptible vibrations in the vehicle through the operation of the electromechanical brake pressure generator according to the invention.

[0014] According to another improvement to the invention, the hydraulic block, preferably rectangular in shape, has a second end side opposite to the first end side, and the electronic control unit is directly disposed at the second end side. This specific arrangement allows the electric motor unit to be directly electrically attached to the electronic control unit, which also forms a prerequisite for the following scheme: the speed sensor and / or rotation direction sensor for the electric motor unit is preferably integrated into the electronic control unit, and the speed sensor and / or rotation direction sensor is disposed in the region of the end of the motor shaft opposite to the transmission unit. The integration of the electric motor unit into the hydraulic block and the direct electrical attachment of the electric motor unit to the electronic control unit allow for direct electrical energy flow between the components, resulting in less electrical circuit loss that generates heat.

[0015] According to a preferred embodiment of the electronic control unit, the electronic control unit is constructed as a structural element arranged on a single electronic circuit board. This electronic structural element not only implements electronic control of the motor unit but also implements hydraulic valve control of the piston / cylinder unit. Thus, the electronic control unit—similar to the transmission unit—can also be constructed in a fairly flat manner to further improve the compactness of the electromechanical brake pressure generator. Attached Figure Description

[0016] Other measures to improve the invention are described in more detail below with reference to the accompanying drawings, in conjunction with a description of preferred embodiments of the invention. Figure 1 A schematic side view of an electromechanical brake pressure generator constructed from the main components described above is shown. Detailed Implementation

[0017] according to Figure 1 The electric motor unit 1 generates a rotary motion a to drive the system according to a pre-defined braking requirement. The electric motor unit 1 essentially consists of a stator 1a fixedly positioned relative to the hydraulic block 6 and a corresponding rotor 1b connected to the shaft 7. The electric motor unit 1 is controlled by an electronic control unit 2. The resulting rotary motion a is converted into a translational motion b by a reduction gear unit 3 with an output spindle drive unit 4, which is then used to piston-operated hydraulic piston / cylinder unit 5.

[0018] In the compactly constructed electromechanical brake pressure generator, the hydraulic block 6, made of light metal, for the piston / cylinder unit 5 also houses the electric motor unit 1 in a functionally integrated sense, thus eliminating the need for a separate housing for it. Here, the motor shaft 7 of the electric motor unit 1 extends axially parallel to the longitudinal axis 8 of the piston 9 of the piston / cylinder unit 5, which is capable of axial movement within the hydraulic block 6.

[0019] At the generally rectangular hydraulic block 6, a transmission unit 3 is directly arranged on the first end side 10. In this embodiment, the transmission unit 3 consists of a multi-stage spur gear transmission 11, which converts the speed output by the electric motor unit 1 into a slower speed, i.e., deceleration, and simultaneously bridges the wheelbase X between the electric motor unit 1 and the spindle transmission unit 4 arranged coaxially with the piston / cylinder unit 5.

[0020] Opposite to the first end side 10, the cuboid hydraulic block 6 has a second end side 12 extending parallel to it, where the electronic control unit 2 is directly arranged. A speed sensor and / or rotation direction sensor 13 for the electric motor unit 1 is integrated into the electronic control unit 2. The speed sensor and / or rotation direction sensor 13 detects the speed and / or rotation direction of the motor shaft 7, and transmits the corresponding measurement signal to the electronic control unit 2 for known control purposes. In this embodiment, the electronic control unit 2 is implemented as a single circuit board 14 on which various electronic structural elements 15 are arranged (exemplarily) for implementing control functions. This controls not only the electric motor unit 1, but also the hydraulic valve control device of the piston / cylinder unit 5—not shown further here.

[0021] This invention is not limited to the preferred embodiments described above. Rather, variations are conceived and are also included within the scope of the following claims. For example, it is also possible to implement the transmission unit 3 in other ways, such as as a traction mechanism transmission or the like. Furthermore, it is also sufficient if the electric motor unit 1 is at least partially housed in the hydraulic block 6 and extends, for example, into the directly adjacent electronic control unit 2 or into the transmission unit 3 via a protruding portion.

Claims

1. An electromechanically driven brake pressure generator for a vehicle hydraulic braking system, comprising an electric motor unit (1) which is controlled by an electronic control unit (2) according to the brake pressure to be applied, and a reduction gear unit (3) having a spindle drive unit (4) on the output side which converts the rotational motion (a) generated by the electric motor unit therein into translational motion (b) to manipulate the piston (9) of a hydraulic piston / cylinder unit (5). Its features are, The piston / cylinder unit (5) is housed in a hydraulic block (6), and the piston (9) of the piston / cylinder unit (5) is able to move within the hydraulic block (6); The stator (1a) and rotor (1b) of the electric motor unit (1) are also housed in the hydraulic block (6), and the motor shaft (7) of the electric motor unit (1) extends at least in the region of the hydraulic block (6). The motor shaft (7) is arranged axially parallel to but not on the longitudinal axis (8) of the piston (9) of the piston / cylinder unit (5). Among them, the hydraulic block (6) made of a light metal alloy has a rectangular envelope geometry. The rectangular hydraulic block (6) has a first end side (10), and the transmission unit (3) is directly arranged at the first end side. The rectangular hydraulic block (6) has a second end side (12) opposite to the first end side (10), and the electronic control unit (2) is directly arranged at the second end side. The first end (10) of the motor shaft extending from the hydraulic block (6) engages with the transmission unit (3), and the second end (12) of the motor shaft extending from the hydraulic block (6) is detected by the electronic control unit (2) for rotational speed and / or rotational direction. The speed sensor and / or rotation direction sensor (13) for the electric motor unit (1) are integrated into the electronic control unit (2), and the speed sensor and / or rotation direction sensor are arranged in the region of the end of the motor shaft (7) opposite to the transmission unit (3).

2. The electromechanically driven brake pressure generator according to claim 1, characterized in that, The size of the hydraulic hole of the hydraulic block (6) is determined in a manner that meets the cooling requirements of the electric motor unit (1).

3. The electromechanically driven brake pressure generator according to claim 1, characterized in that, The transmission unit (3) is constructed as a multi-stage spur gear transmission (11), which is connected to the wheelbase (X) between the electric motor unit (1) and the spindle transmission unit (4) arranged coaxially with the piston / cylinder unit (5).

4. The electromechanically driven brake pressure generator according to claim 3, characterized in that, The gears of the multi-stage spur gear drive (11) are made of plastic.

5. The electromechanically driven brake pressure generator according to claim 1, characterized in that, The electronic control unit (2) is constructed in the form of an electronic structural element (15) arranged on a single circuit board (14), which not only implements electronic control of the motor unit (1) but also implements hydraulic valve control of the piston / cylinder unit (5).

6. A vehicle comprising a brake pressure generator capable of electromechanical drive according to any one of claims 1-5.

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