Electrically controlled drive units

Abstract

The invention relates to an electrically controllable drive unit (10) comprising an electric motor (12), the electric motor having a rotor (14) which can be driven for a rotational movement, a motor shaft (16) which is connected to the rotor (14) in a rotationally fixed manner, and a signal transmitter (24) of a sensor device for electronically detecting and evaluating the rotation angle of the motor shaft (16). The signal transmitter (24) is indirectly anchored to the motor shaft (16) via a retaining element (28). The invention proposes a retaining element (28) which is made as a hollow cylinder having an open first end, the retaining element (28) being fixed to the motor shaft (16) with the first end, and the hollow cylinder having a second end facing away from the motor shaft (16), the second end having at least one retaining element region (46) which projects into the open cross section of the retaining element (28).

Description

Technical Field

[0001] The invention relates to an electrically controllable drive unit. Background Art

[0002] Such a drive unit is used, for example, in an electronically slip-controlled brake system of a motor vehicle to drive a pressure generator within the scope of brake pressure control. The drive unit is electrically actuated by an electronic control unit of the brake system. When the drive unit is electrically actuated, the pressure generator actuated thereby delivers pressure medium within the brake circuit from a storage container of the brake system to the connected wheel brakes. A brake pressure then builds up in the wheel brake in proportion to the amount of pressure medium delivered.

[0003] By means of an additional control device that can be controlled by the electronic control unit, this brake pressure can be adapted in a wheel-specific manner to the slip ratio currently present at the respectively assigned wheel of the vehicle. This can prevent wheel slip and thus improve the driving stability of the vehicle. In addition, depending on the current traffic situation, the braking process can be carried out independently of the driver.

[0004] In these control and / or regulating processes, the amount of pressure medium displaced by the pressure generator represents a decisive characteristic variable, which can be determined from the actuation signal of the pressure generator. For this purpose, the existing sensor device detects the rotation angle of the rotor of the drive unit and transmits the measured rotation angle signal to the electronic control device for evaluation.

[0005] Such a sensor device is constructed from a signal transmitter that rotates with the motor shaft and an associated signal receiver that is arranged in a fixed position opposite the signal transmitter.

[0006] The prior art of the present invention is disclosed, for example, in DE 10 2017 218 648 A1.

[0007] Such a drive unit 10 is also described in the present patent application. Figure 1. This drive unit 10 includes an electric motor 12, which has a rotor 14 that can be driven to perform a rotational movement and a motor shaft 16 that is non-rotatably connected to the rotor 14. The rotor 14 is conventionally constructed and has an iron core and a plurality of coils that are wound around the iron core and arranged next to each other in the circumferential direction of the iron core. In a known manner, the coils form magnets in the energized state, which interact with magnets that are fixedly arranged on opposite inner surfaces of a housing 18 of the drive unit 10 in such a way that the rotor 14 and the motor shaft 16 perform a rotational movement. For this purpose, the motor shaft 16 is exemplarily supported in the housing 18 in a rotatable manner by means of a rolling bearing 20. According to Figure 1 Arranged by way of example on the motor shaft 16 are a plurality of eccentric elements 22 in order to actuate a device (not shown) which is arranged transversely to the motor shaft 16 .

[0008] according to Figure 1 Detail X shows a signal transmitter 24 of a sensor device for electronically detecting and analyzing the rotation angle of the rotor 14. This signal transmitter 24 is arranged on the end face of the motor shaft 16 facing away from the rotor 14. The signal transmitter has a magnetic element 26, which is indirectly fixed to the motor shaft 16 via a retaining element 28. The retaining element 28 is cup-shaped and made of a non-magnetic material. From the bottom of the retaining element 28, a mandrel 30 protrudes, and the retaining element 28 is pressed into the assigned central hole 32 of the motor shaft 16 with the mandrel and bonded therein. A blind hole-shaped receiving portion 34 open to the outside is constructed on the side of the retaining element 28 opposite to this, and the magnetic element 26 is installed in the receiving portion in a form-fitting and outwardly flush manner. The fixing of the magnetic element 26 in this receiving portion 34 of the retaining element 28 is also carried out by an adhesive connection.

[0009] Under the operating conditions of this drive unit, the rotor 14 is often greatly accelerated or decelerated. The dynamic, axial and also radial forces that occur here load the adhesive connection described and can cause the magnetic element 26 of the signal transmitter 24 to execute undesired relative movements, in particular axially, relative to the motor shaft 16. These relative movements lead to inaccuracies in the detection of the rotation angle passed by the motor shaft 16 and thus to possible errors in the electrical control of the electric motor 12 of the drive unit 10 or in the regulation of the displaced pressure medium quantity. This ultimately has an undesired influence on the brake pressure regulation that is carried out. Summary of the invention

[0010] The object of the present invention is to improve a drive unit in the prior art. This object is achieved by the following solution of an electrically controllable drive unit: the drive unit has an electric motor, the electric motor has a rotor that can be driven for a rotational movement and a motor shaft that is connected to the rotor in a rotationally fixed manner; and has a signal transmitter of a sensor device arranged on the motor shaft, the sensor device is used to electronically detect and analyze the rotation angle of the motor shaft, the signal transmitter includes a retaining element and a magnetic element arranged on the retaining element, characterized in that the retaining element is made as a hollow cylinder, the magnetic element is retained inside the hollow cylinder, wherein the retaining element has an open first end , the retaining element is fixed to the motor shaft with the first end together with the magnetic element, and wherein the retaining element has a second end facing away from the motor shaft, the second end has at least one retaining element area extending into the open cross section of the retaining element, the magnetic element abuts against the retaining element area, wherein the magnetic element of the signal transmitter is fixed inside the retaining element by means of a clamping element, wherein this clamping element has a base spanning the cross section of the magnetic element and a leg connected to the base, the leg extending at the circumference of the magnetic element in the direction of the longitudinal axis of the motor shaft.

[0011] Compared to the prior art, the electrically controllable drive unit according to the invention has the following advantages: the signal transmitter is fixed to the motor shaft without an adhesive connection. As a result, elasticity is eliminated and the detection of the rotation angle signal is carried out with greater precision. With the increased precision, the electrical controllability of the drive unit is improved and thus the possible deviation between the actually required pressure medium quantity and the desired target value is reduced. In addition, the large-scale production process of the drive unit can be simplified due to the omission of the adhesive connection and the processing time and processing costs can be saved.

[0012] As described above, according to the invention, these advantages are achieved by a retaining element which is designed as a hollow cylinder, inside which the magnetic element of the signal transmitter is received. The hollow cylinder has an open first end, the retaining element including the magnetic element inserted therein is fixed to the motor shaft with the first end, and the hollow cylinder has a second end opposite the first end, which has retaining element sections which extend into the open cross section of the hollow cylinder. The magnetic element of the signal transmitter abuts against these retaining element sections and is thereby fixed to prevent it from falling out of the retaining element.

[0013] The retaining element according to the invention can be manufactured cost-effectively by deep-drawing and accommodates the magnetic element of the signal transmitter very rigidly, so that the magnetic element assumes a constant relative position relative to the associated signal receiver over the service life and independently of the loads occurring during operation of the drive unit.

[0014] Further advantages and advantageous developments of the invention emerge from the following description.

[0015] Advantageously, the motor shaft has a section at its end facing the retaining element, which is set back in its outer diameter relative to the outer diameter of the motor shaft. The hollow cylindrical retaining element is fixed at this section with its open first end. The retaining element can be pushed onto this shoulder of the motor shaft in a simple manner and method and centered relative to the longitudinal axis of the motor shaft at the same time. Subsequently, the retaining element is connected to the motor shaft by means of a first welding connection material lock. The transition zone from the shoulder to the circumference of the motor shaft constitutes a shoulder, which serves as an axial stop for the retaining element when it is installed on the motor shaft. The coaxiality of the retaining element or the signal transmitter relative to the longitudinal axis of the motor shaft and the length tolerance of the motor shaft-retaining element-unit can be maintained within relatively narrow limits by means of the design measures described about the component.

[0016] In another advantageous embodiment of the invention, the magnetic element of the signal transmitter is fixedly held inside the retaining element by means of a clamping element. The retaining element, for its part, is materially connected to the retaining element by means of a second welded connection. The welded connection increases the deformation strength of the unit consisting of the retaining element, the signal transmitter and the motor shaft, and in addition the clamping element together with the second welded connection itself ensures that the magnetic element is fixed in the retaining element in the event of temperature changes. In addition, the clamping element can set a constant air gap between the end face of the motor shaft and the magnetic element. The air gap is used to guide the magnetic flux in the direction of the signal receiver, which is beneficial to the signal strength or to the signal detection. The clamping element can be produced cost-effectively, for example in a non-cutting manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] An exemplary embodiment of the invention is illustrated with reference to the drawings and is explained in more detail in the following description.

[0018] The accompanying drawings include 3 figures in total, among which:

[0019] Figure 1 A drive unit according to the prior art is shown;

[0020] Figure 2 The embodiment of the present invention is shown in accordance with Figure 1 Details of X; and

[0021] Figure 3 The perspective view shows the case where there is no magnetic element installed therein. Figure 2 signal transmitter. DETAILED DESCRIPTION

[0022] Figure 2 The design scheme according to the present invention shows that Figure 1 Detail X. The motor shaft 16 of the drive unit 10 is shown in the region of the end of the motor shaft facing away from the rotor 14 of the electric motor 12 (not shown). Figure 2 This end of the motor shaft 16 is equipped with a signal transmitter 24 of a sensor device.

[0023] As is known per se, the signal transmitter 24 comprises a magnetic element 26, which is fixed to the end face of the motor shaft 16 by means of a retaining element 28 made of a non-magnetic material. According to the invention, the retaining element 28 is designed as a hollow cylinder, inside which the magnetic element 26 is received and fixedly anchored by means of a clamping element 36. The hollow cylinder has an open first end, with which it is pushed onto a shoulder 38 which is set back in its outer diameter relative to the outer diameter of the motor shaft 16. The transition from the circumference of the motor shaft 16 to the circumference of the shoulder 38 is designed as a right-angled shoulder 40, for example. The retaining element 28 rests on this shoulder 40 with a circumferential, radially projecting collar 42, which is formed at the open end of the retaining element 28. The retaining element 28 can be aligned concentrically with the longitudinal axis L of the motor shaft 16 via the shoulder 38 and its shoulder 40 and, after it has been first fixed to the motor shaft 16 in a form-fitting manner by means of a first welded connection 44, can also be connected to the motor shaft 16 in an integrally bonded manner. Figure 2 In the embodiment, the weld is formed by means of an annularly circumferential weld seam, but as an alternative, a plurality of weld points or weld seam sections which follow one another can also be arranged circumferentially.

[0024] The second end of the retaining element 28, which is opposite the open first end of the retaining element 28 and thus faces away from the motor shaft 16, forms a retaining element region 46, which can protrude into the open cross section of the hollow cylindrical retaining element 28 and, for example, extends transversely over the entire open cross section of the retaining element 28. The magnetic element 26 of the signal transmitter 24 rests axially against the retaining element region 46 and is thus mechanically secured against falling out of the interior of the retaining element 28.

[0025] The clamp element 36 serves to fix the magnetic element 26 axially inside the retaining element 28. The clamp element is inserted into the retaining element 28 under radial prestressing and is also connected to the magnetic element 26 in a form-locking manner. The clamp element 36 is preferably made of a right-angled sheet metal strip and is bent in a U-shape. Correspondingly, the clamp element 36 has a base 48 that spans the end face of the magnetic element 26 that is inside the retaining element 28 and also has legs 50 that are formed at both ends of this base 48 and extend from it at right angles in the same direction. A groove-shaped recess 52 is formed on the magnetic element 26 at its circumference, extending in the direction of the longitudinal axis L of the motor shaft 16 from the inner end face of the magnetic element 26 to a short distance in front of the opposite end face of the magnetic element. One of the legs 50 of the clamp element 36 is located in each recess 52.

[0026] The clamp element 36 is connected to the retaining element 28 in a materially bonded manner via a second welded connection 54. The weld seam of this second welded connection 54 is formed in accordance with Figure 2 The magnetic element 26 of the signal transmitter 24 is thus held between the retaining element region 46 and the clamping element 36 , which extends into the open cross section of the hollow cylindrical retaining element 28 .

[0027] Between the end face of the magnetic element 26 located within the retaining element 28 and the facing end face of the motor shaft 16 there is an axial spacing and thus an air gap 56 which at least largely excludes any influencing of the magnetic flux of the magnetic element 26 via the motor shaft 16 .

[0028] Figure 2 The explained holding element 28 is shown again in a perspective view. For the sake of simplicity, the components or component sections corresponding to each other are shown in FIG. Figure 2 and 3 The same reference numerals are provided in Figure 3 The magnetic elements of the signal transmitter 24 are not shown in FIG. 1 , in order to be able to better illustrate the design of the retaining element 28 and the clamping element 36 .

[0029] In the present exemplary embodiment, the holding element region 46 that projects into the open cross section of the holding element 28 is designed as a cross piece that extends over the entire opening cross section of the holding element 28 and divides this opening cross section into two mutually separate partial opening cross sections 58. In principle, it is conceivable to provide a plurality of such cross pieces and to divide the opening cross section of the holding element 28 into further partial opening cross sections.

[0030] Of course, modifications or additions to the described exemplary embodiments are conceivable without departing from the basic idea of ​​the invention explained at the outset.

Claims

1. The drive unit can be electrically controlled, An electric motor (12) has a rotor (14) which can be driven to perform a rotational movement and a motor shaft (16) which is connected to the rotor (14) in a rotationally fixed manner, and a signal transmitter (24) arranged on the motor shaft (16) and having a sensor device for electronically detecting and evaluating the rotation angle of the motor shaft (16), the signal transmitter comprising a retaining element (28) and a magnetic element (26) arranged on the retaining element (28), It is characterized in that The retaining element (28) is made as a hollow cylinder, the magnetic element (26) is retained inside the hollow cylinder, wherein the retaining element (28) has an open first end, the retaining element (28) is fixed to the motor shaft (16) with the first end together with the magnetic element (26), and wherein the retaining element (28) has a second end facing away from the motor shaft (16), the second end having at least one retaining element region (46) protruding into the open cross section of the retaining element (28), the magnetic element (26) abutting against the retaining element region, In which, the magnetic element (26) of the signal transmitter (24) is fixed inside the retaining element (28) by means of a clamping element (36), wherein the clamping element (36) has a base (48) spanning the cross section of the magnetic element (26) and a leg (50) connected to the base (48), and the leg extends at the circumference of the magnetic element (26) in the direction of the longitudinal axis L of the motor shaft (16).

2. The drive unit according to claim 1, It is characterized in that The motor shaft (16) has, at its end facing the retaining element (28), a shoulder (38) in its outer diameter which is set back relative to the outer diameter of the motor shaft (16), to which the signal transmitter (24) is fastened with its open end of the retaining element (28).

3. The drive unit according to claim 1 or 2, It is characterized in that The transition from a shaft shoulder (38) of the motor shaft (16) to the circumference of the motor shaft (16) forms a shoulder (40) against which the retaining element (28) rests.

4. The drive unit according to claim 1 or 2, It is characterized in that The clamping element (36) is connected to the retaining element (28) in a materially bonded manner.

5. The drive unit according to claim 1 or 2, It is characterized in that The clamp element (36) is connected to the retaining element (28) in a materially bonded manner via a first welded connection (44), which extends at least partially in a circumferential direction of the retaining element (28).

6. The drive unit according to claim 1 or 2, It is characterized in that The retaining element (28) is connected to the motor shaft (16) in a materially bonded manner.

7. The drive unit according to claim 1 or 2, It is characterized in that The retaining element (28) is connected to the motor shaft (16) in a materially bonded manner via a second welded connection (54), which extends at least partially in a circumferential direction of the retaining element (28).

8. The driving unit according to claim 1 or 2, It is characterized in that A retaining element region (46) of the retaining element (28) is designed as a cross-piece which divides an open cross section of the retaining element (28) into a plurality of partial opening cross sections (58).

9. The driving unit according to claim 1 or 2, It is characterized in that The magnetic element (26) of the signal transmitter (24) is fixed between a holding element region (46) of the holding element (28) and a base (48) of the clamping element (36).

10. The driving unit according to claim 1 or 2, It is characterized in that The extension of the retaining element (28) in the direction of the longitudinal axis L of the motor shaft (16) and the extension of the magnetic element (26) in the direction of the longitudinal axis L of the motor shaft (16) are coordinated with each other in such a way that, when the signal transmitter (24) is mounted on the motor shaft (16), an air gap (56) exists between the end face of the motor shaft (16) and the end face of the magnetic element (26) facing the motor shaft (16).

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