JP2874876B2 - Electric drive type preparation drive - Google Patents

Description

Description: The invention relates to an electrically actuated adjustment drive of the type described in the preamble of claim 1.

2. Description of the Prior Art In many technical fields, large translational forces, i.e. with small mechanical powers and with very short adjustment distances, i.e.
There is a need for an adjusting drive (actuator) which must release the adjusting force and in particular the holding force only occasionally in a short time. For this purpose, an electric motor or an electromagnetic lifting magnet, which is usually followed by a reduction transmission, is used.

Suitable lifting magnets having a relatively large volume and a relatively large weight have a non-linear excitation current / force characteristic curve, so that the remarkable fluctuation of the holding force released even when the manufacturing error is relatively small. To produce Therefore, by using such an electromagnetic lifting magnet,
In some cases, the adjusting technical costs are high or the lifting magnets are often unusable for space or weight reasons.

On the other hand, the adjustment or holding force released by the electric motor, which is followed by a reduction gearing, is not significantly related to manufacturing errors. However, such an adjustment drive also requires a relatively large structural volume if the adjustment drive must occupy a defined end position in an uncontrolled manner, as is required in many applications. And
That is, since the magnitude of the total transmission ratio of the reduction transmission is limited based on transmission friction or self-locking action, the electric motor itself must necessarily have a considerable structural volume. Furthermore, in such an adjusting drive, in the case of a large holding force, (if due to its good adjustability) a direct current commutator motor is used, the commutator strips will wear significantly.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electric drive drive which is inexpensive, has good performance and is as compact as possible, that is, which requires as little structural space as possible.

According to the invention, the object is achieved by an electrically driven adjusting and driving device according to the invention as set forth in the characterizing part of claim 1.

Advantageous configurations of the invention are set out in the other claims.

The adjusting drive according to the invention can be operated at a relatively low current and the adjusting or holding force of the adjusting drive can be controlled or adjusted simply and accurately.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The electric drive of the present invention comprises an electric motor 1, a pneumatic pump 2 and a pressure box 3, which are functionally connected to one another and are structurally identical. It is integrated into a compact structural unit with a relatively small structural volume.

The electric motor, the electric motor torque that is released can be proportional to thus easily controlled or adjusted to a controllable motor current I _M are used. The electric motor therefore forms a linear component in terms of regulating technology. Advantageously, a continuously excited DC motor is used, which has a very small construction size and is approximately up to 6 to
It has an output of 60 watts. The low motor current I _M of the DC motor is supplied from the vehicle's power grid.

The electric motor 1 rotates continuously during running operation. The electric motor 1 drives a pneumatic pump, which also has a linear characteristic curve, ie a pneumatic pump whose discharge pressure is proportional to the driving torque. This means that the delivered volume flow of the pneumatic pump is proportional to the drive speed. In this case, one of the known vane pumps is preferably used. FIG. 2 shows a sectional view of such a vane pump, in which the rotor eccentrically mounted in the cylinder chamber of the pump housing 21 of the vane pump is designated by the reference numeral 22 and is movably mounted in this rotor. The indicated vane is indicated by reference numeral 23. The vane pump has a suction connection and a pressure feed connection as in the prior art, and in FIG. 1 only one of the connections is designated by the reference numeral 24.

Depending on the intended use of the adjusting drive, the pneumatic pump can be configured as a low pressure generating unit or an overpressure generating unit. This means that, when using a vane pump, the following is true: the downstream pressure box is connected in one case to the suction connection of the vane pump and in another case to the pressure connection. Means

Preference is given to using a vane pump with an absolute outlet or discharge pressure of approximately 2.5 bar, ie an atmospheric overpressure of 1.5 bar. At such pressure levels, no sealing problem usually arises.

The pressure difference used of approximately 1.5 bar is almost three times greater than the pressure difference of approximately 0.5 bar used in motor vehicles or otherwise commonly used for servo purposes, and this pressure difference of 0.5 bar Are used by intake pipe low pressure in otto engines or by special diesel low pressure pumps in diesel vehicles. The high pressure available is important in downstream components that are designed to be small depending on the structural volume.

The power of the pressure box is transmitted by a pressure box which is replenished by the discharge pressure of the pneumatic pump 2 via the connection 24 and which is configured as an overpressure or low pressure pressure box depending on the intended use and the pneumatic pump. Dovetail stick 32
A relatively large pressing or pulling force (see FIG. 1) can be produced even when the adjustment distance of the pressure box is small, the magnitude of this force being particularly relevant to the design of the pressure-loaded surface of the pressure box diaphragm 31. doing. Advantageously, the pressure box is designed so that the adjustment and holding forces generated by the pressure box are approximately up to 100 to 1000 Newtons.

By appropriately configuring the pneumatic pump / pressure box components, the required "transmission" between the continuously rotating electric motor 1 and the linear regulating or holding force F emitted by the regulating drive is achieved. The "ratio" can be adapted to the respective use requirements.

As As illustrated in Figure 3, between the successive control or adjustable motor current of the electric motor 1 rotates I _M and pneumatic pump 2 the outlet pressure or discharge pressure Delta] p, already mentioned If the components connected to each other have a linear characteristic curve, a substantially linear relationship results. Therefore, between the released regulating or holding force F of the pressure box 3 and the controllable motor current I _M ,
A linear relationship arises, which makes the required control or regulation of the force relatively simple.

The electrically actuated adjusting drive according to the invention has, in addition to a structural form which saves weight and space and good adjustability, a pressure box 3 if the adjusting drive itself controls the mechanical course. Some have the additional advantage of acting as a flexible damping element between the electric motor and the force release.

[Brief description of the drawings]

The drawings show an embodiment of the present invention, and FIG.
Side view an example of an adjusting drive shown partially broken of the present invention, FIG. 2 is a cross-sectional view taken along the first drawing line II-II, FIG. 3, the motor current I _M and the pump discharge FIG. 3 is a diagram illustrating a relationship with a pressure Δp. DESCRIPTION OF SYMBOLS 1 ... Electric motor, 2 ... Pneumatic pump, 3 ... Pressure boss, 21 ... Pump casing, 22 ... Rotor, 23
…… Vane, 24 …… Connection part, 31 …… Pressure box diaphragm, 32 …… Protrusion rod

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-63-135603 (JP, A) JP-A-62-157284 (JP, A) JP-A-61-142377 (JP, A) 32802 (JP, U) JP-A 63-151282 (JP, U) JP-A 50-7414 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) F15B 15/18 B62D 5 / 06 F04C 18/344 351

Claims (2)

(57) [Claims] 1. An electrically actuated adjusting drive, preferably used in a power steering of a motor vehicle, for generating a large mechanical and translational adjusting and holding force with a small mechanical output. A type in which the magnitudes of the adjusting force and the holding force are continuously controllable; (a) releasing a torque proportional to a controllable motor current or rotor current (I _M ); An electric motor (1) rotating continuously, preferably a continuously excited DC motor; (b) an electric motor (1) having a linear relationship between drive torque and discharge pressure (Δp) Pneumatic pump (2), preferably a vane pump, continuously driven by: (c) a pneumatic pump having a linear relationship between the regulating and holding force (F) and the input pressure (Δp) Depending on the discharge pressure of the pump (2) Wherein the continuous pressure box (3) to be replenished or similar is provided Te, electrically driven adjusting drive. 2. An electric motor (1) having a maximum power of approximately 6 watts to 60 watts, and a pneumatic pump (2) comprising approximately 2.
2. The regulating drive according to claim 1, which has an absolute outlet or discharge pressure of 5 bar and the pressure box (3) has a maximum regulating and holding force of approximately 100 to 1000 Newtons.