阅读说明：本技术 将第一部件固定在第二部件中的方法以及由此制造的单元、特别是致动器 (Method for fixing a first component in a second component and unit, in particular actuator, produced thereby ) 是由 E-M·艾伯特 M·德里诺夫斯基 于 2019-09-27 设计创作，主要内容包括：本发明涉及一种用于将第一部件固定在第二部件中的方法。包覆第二部件的内侧的至少一部分以形成塑料衬套,通过压配合将第一部件在第二部件的塑料衬套内居中定位并固定。以此方式实现了第一部件在第二部件中的可靠固定。本发明还涉及一种通过这种方法形成的单元。(The invention relates to a method for fastening a first component in a second component. Over-wrapping at least a portion of the inside of the second component to form a plastic bushing, and centering and securing the first component within the plastic bushing of the second component by press-fitting. In this way, a secure fixing of the first component in the second component is achieved. The invention also relates to a cell formed by such a method.)

1. A method for fastening a first component (2) in a second component (1), wherein the first component (2) is centered and fastened in the second component (1) by means of a press fit, having the following steps:

-wrapping at least a part of the inside of the second component (1) to form a plastic bushing (8); and

-centering and fixing the first component (2) within the plastic bushing (8) of the second component (1) by means of a press fit.

2. Method according to claim 1, characterized in that the cladding is carried out with a plastic bushing (8) having a coefficient of thermal expansion matched to the coefficient of thermal expansion of the first component (2) and/or the second component (1) in such a way that critical stresses are not exceeded in the components (1, 2) during/after the press-fit process in the operating temperature range and there is no loss of contact between the components (1, 2).

3. Method according to claim 2, characterized in that the coating is performed with a plastic bushing (8) having a coefficient of thermal expansion as follows: the coefficient of thermal expansion satisfies the above conditions in the operating temperature range of-40 ℃ to 200 ℃.

4. Method according to one of the preceding claims, characterized in that a direct current motor is used as the first component (2) and an actuator housing is used as the second component (1).

5. Method according to one of the preceding claims, characterized in that the first component (2) used has a central elevation (3) on the bottom side, which engages in a recess of the second component (1), and the inside of the recess is covered.

6. Method according to one of the preceding claims, characterized in that the second component (1) is clad in its bottom region with a plastic bush (8) having an H-shaped cross-section, into which the boss (3) of the first component (2) engages.

7. Method according to one of the preceding claims, characterized in that the centering of the first component (2) is always performed in one of the two functional phases: an inner press fit (7) between the second component (1) and the coated plastic bushing (8), and an outer press fit (6) between the second component (1) and the coated plastic bushing (8).

8. A cell formed by the method of any one of claims 1 to 7.

9. Unit according to claim 8, characterized in that the unit is an actuator, in that an electric motor, in particular a DC motor, is fixed in the actuator housing by press fit.

Technical Field

The invention relates to a method for fixing a first component in a second component, wherein the first component is centered and fixed in the second component by means of a press fit.

Background

Such a method is known and is used, for example, for fastening an electric motor, in particular a dc motor, in a housing of an actuator. Such actuators can be used, for example, for controlling certain components, wherein an electric machine is connected to a transmission that provides a corresponding movement variable.

The first component, for example a direct current motor, is fixed in the second component, for example an actuator housing, by means of a press fit, and this press fit must be suitable for both arbitrary components, since the tolerance ranges in the respective components must be taken into account. Furthermore, there is the problem that the press fit must be suitable for all temperatures within the respective operating temperature range (for example between-40 ℃ and +200 ℃). However, since the first and second components are usually made of different materials having different coefficients of thermal expansion, and since both materials have a certain range of dimensional tolerances at different temperatures and there is some dimensional difference, it may happen that the press-fit force between the first and second components becomes too large and in this way creates corresponding stresses in the components, or that the press-fit force between the first and second components becomes too small, so that there is no longer any contact between the components and a gap is formed between the components.

Disclosure of Invention

The invention is based on the object of providing a method of the type mentioned at the outset, with which a particularly reliable fastening of the components to one another can be achieved.

According to the invention, this object is achieved by a method of the type specified, comprising the steps of:

wrapping at least a portion of the inside of the second component to form a plastic bushing; and

centering and fixing the first component within the plastic bushing of the second component by means of a press fit.

Without affecting the respective tolerance ranges of the components, the invention proposes to arrange an additional element in the system, which additional element is produced by the inside cladding of the second component. The first component is then centered and secured in the plastic sleeve that is wrapped over the second component.

By providing an intermediate element between the two components, the transition between the first component and the second component can be compensated or balanced, so that the corresponding differences in the press-fit forces can be greatly reduced or normalized. Thus, despite differences in materials, differences in thermal expansion coefficients, differences in temperature, etc., the occurrence of excessively high press-fit forces and excessively low press-fit forces, which would lead to the above-mentioned disadvantages, is avoided.

In the method according to the invention, the coating is preferably carried out with a plastic liner: the coefficient of thermal expansion of the plastic bushing is matched to the coefficient of thermal expansion of the first and/or second component in such a way that critical stresses are not exceeded in the components during/after the press-fit process in the operating temperature range and there is no loss of contact between the components. In particular with a plastic bushing having a coefficient of thermal expansion which satisfies the above conditions in the operating temperature range of-40 ℃ to 200 ℃.

The material for the sheathed plastic bushing is therefore selected such that the coefficient of thermal expansion of the plastic bushing, in combination with the respective coefficients of thermal expansion of the first and second component, does not cause damage to the system in the temperature range mentioned and, furthermore, does not cause gaps between the components which could lead to a loosening of the press fit.

The method according to the invention is preferably used in applications in which a direct current motor is used as the first component and an actuator housing is used as the second component. The actuator housing is substantially cylindrical. As mentioned above, it is at least partially coated on its inner side with a plastic lining. Whereby either the bottom or the cylindrical inner wall of the actuator housing can be covered by a plastic bushing. It is also possible to coat only the portion of the cylindrical inner wall that is used to provide the press fit.

In a particularly preferred embodiment, a first component is used which has a central projection on the underside, which engages in a recess of a second component, and the inside of the recess is clad to form a plastic bush or a part thereof there. For example, a support bushing (bronze bushing) for a rotor of a direct current motor may be arranged in the above-described manner. The boss of the first component is then arranged by press-fitting in the recess of the second component, which is covered by the plastic bush.

In particular, in the method according to the invention, the second component is sheathed in its base region with a plastic sleeve having an H-shaped cross section, in which the projection of the first component engages. The centering of the first component is always achieved in one of the two functional phases: an inner press fit between the first component and the covered plastic bushing, and an outer press fit between the first component and the covered plastic bushing, because the covered plastic bushing contacts the second component from both the inside and the outside.

The invention is not limited to the above-described application in any way. The invention can be used in any case where assembly by means of press fitting is required and in particular where the corresponding system has to be operated over a large temperature range.

In any case, in the method according to the invention, the magnitude of the axial force of the press fit should also be such that the respective components, such as the direct current motor and the actuator housing, are not damaged during the assembly process.

According to the invention, the stresses generated in the system by press fitting are reduced below critical limits, since the different coefficients of thermal expansion of the materials used for the motor housing, the coated plastic bushing and the actuator housing are matched. In particular, for any temperature within the respective temperature range required for the system function (for example-40 ℃ to 200 ℃), the contact between the components does not disappear, since the centering process is always in the following two phases:

stage 1: an internal press fit between the second component (actuator housing) and the coated plastic bushing;

stage 2: an external press fit between the second component (actuator housing) and the coated plastic bushing.

Depending on the actual dimensional values and the actual temperature, the centering position is switched between phase 1 and phase 2 and vice versa, so that a press-fit force is always present during this transfer.

The invention also relates to a cell formed by a method of the above type. The unit is preferably an actuator in which a motor, in particular a direct current motor, is fixed by press fit.

Drawings

The invention is explained in detail below with the aid of embodiments with reference to the drawings. The figures show:

fig. 1 shows a prior art fastening of a first component embodied as a direct current motor in a second component embodied as an actuator housing by means of a press fit;

FIG. 2 is a view similar to FIG. 1, with press-fit areas identified; and

fig. 3 shows the fixation of a first part in a second part in the invention.

Detailed Description

In the method shown in fig. 1, a first, approximately cylindrical component 2, here a direct current motor with a corresponding housing, is fixed in a second component 1, here an actuator housing. Here, the approximately cylindrical first member 2 is inserted into the approximately cylindrical inner space of the second member 1, i.e., is centrally positioned, and is fixed by press fitting.

The first part 2 has on its underside a boss 3 which may contain, for example, a bronze bushing for supporting a rotor 10 of a direct current motor.

Fig. 2 shows a press-fit region 5 between the two components, which ensures the fixation of the direct current motor in the actuator housing.

Since the first component 2, i.e. the motor housing, and the second component 1, i.e. the actuator housing, are each made of different materials with different coefficients of thermal expansion, and both the first component and the second component have a given range of dimensional tolerances and a certain dimensional deviation at different temperatures, the press-fit force between the first component and the second component may become too large or too small. The problems caused by this have already been mentioned at the outset.

These problems are overcome by the method according to the invention. Here, at least a part of the inner side of the second component 1 is first sheathed to form the plastic bushing 8. The cross-section of such an H-shaped plastic bushing is indicated with reference numeral 8. In this embodiment, the bottom of the interior space of the second component 1 has a central depression for receiving the bearing boss 3 of the motor housing and is coated in the region of this depression such that a plastic bushing 8 with an H-shaped cross section is obtained, as shown in fig. 3. The cladding should preferably be achieved using a plastics material having a coefficient of thermal expansion between that of the first and second parts.

The bearing boss 3 of the first component 2 is then centrally located and fixed within the formed plastic bush 8 by press-fitting. This results in an internal press fit between the plastic bush 8 and the second component 1, as shown at 7, and an external press fit between the plastic bush 8 and the second component 1, as shown at 6, since the overmolded plastic bush 8 contacts the second component 1 both with its radial outside and with its radial inside due to its H-shape. Depending on the actual dimensional values and temperature, the transition from stage/phase 1 (internal press fit 7 between the second component 1 and the coated plastic bushing 8) to stage 2 (external press fit 6 between the second component 1 and the coated plastic bushing 8) and vice versa from stage 2 to stage 1 takes place in the centered position, so that a press fit force is always present during this transition.

The coated plastic bushing 8 thus achieves a secure fixation even at high temperature differences and in the case of different materials of the first part and the second part.