DE19800989A1 - Short design powerful axial cylinder motor - Google Patents

Abstract

For motor speed reduction single stage eccentric gears with involute teeth are used so thin that the individual discs forming the inner gear can be stampings. The external teeth on that gear can be formed on the discs by injection molding. The bearing surfaces of the teeth are convex on concave with the same curvature.

Description

Drum motors are usually gearboxes with multi-stage spur gear or Planetary gears or eccentric gears with cycloids (499227) or Involute toothing (DE 196 18 248) applied.

The application of the underlying structure (Fig. 1 and Fig. 2) shows an eccentric gear with a high reduction ratio.

The weak point of all these gears is the line of contact of the gearing.

All previously known transmissions have the disadvantage that the power transmission takes place only by line contact. In spur gear z. B. carries only one tooth in the output stage with a maximum tooth width of approx. 10 times the module. The line contact is a maximum of approximately 0.1 mm wide (Hertzian pressure), so that a transfer area of approximately 0.1 mm × 10 mm = 1 mm ² is present.

The same applies to planetary gears, except that 3 or 4 planets are used, so that approx. 0.1 mm × 10 mm × 4 teeth = 4 mm ² .

In cyclo gearboxes, there are approx. 4 to 8 teeth so that 0.1 mm × 8 teeth × 10 mm = 8 mm ² applies.

Acbar and eccentric gears with involute teeth have up to 10 teeth with line contact. Here, 0.1 mm × 10 mm × 10 teeth = 10 mm ² applies.

A dimensioning has been found in the eccentric gear with involute toothing, which has the advantage over other types of toothing that several teeth are flat, as can be seen from FIGS. 3 and 4.

With involute teeth, there are flat, convex on concave teeth with the same curvature. This assumes elastic stretch and a lubricant film of a few hundredths of a millimeter. This can be seen from FIGS . 3a and 4a, from the dimensions of the tooth head and tooth base. This allows significantly higher loads and less wear on the teeth.

A transmission area of 1.5 mm tooth height × 10 mm tooth width × 10 teeth = 150 mm ^{2 is} load-bearing. This enables the gears to be made narrower, e.g. B. 6 mm wide. Then the toothing with an area of 1.5 mm tooth height × 6 mm tooth width × 10 teeth = 90 mm ² . The toothing now bears with a strength of the polyamide of approx. 40 N / mm ² (at maximum operating temperature) × 90 mm ² = 3600 N, so that the maximum drum motor torque can be transmitted (see technical data supplement).

The teeth are designed so that no change in the pressure angle is required. The externally toothed wheel receives a profile shift factor of X = 0.2 × module. The internal toothing is carried out with a profile shift factor of x = -1 × module. This selection of the profile shift factors creates a flexurally stable tooth and a large overlap of the tooth flanks (without shortening the head) is achieved. There is also an interference-free toothing (see Fig. 1 + 2 + 3 + 4), even with tooth number differences of one, z. E.g. 90-89. Depending on the direction of rotation, the meshing area of the gearing is divided into a right-hand or a left-hand one.

The internal gear consisting of a disc ( Fig. 1 + 2) is designed so narrow that it can be finely punched.

Since the pin holes in the gearwheel in the externally toothed gear ( Fig. 5, items 3 + 4) are to be made with only small web widths, they cannot be made from a stamped part (6 mm thick). Therefore, this part is composed of several disks (1.5 mm thick) ( Fig. 10). Since the steel toothing generates a relatively high noise level, a toothing made of polyamide 6 is injection molded in a suitable plastic injection mold with interchangeable toothing inserts.

The two inner steel disks of the external gear are larger and with holes protruding from the outer steel discs. Here the plastic teeth claw when spraying. The plastic toothing wraps itself around the steel discs like an articulated chain. Leave the steel washers is very precise and extremely inexpensive with a functional design Manufacture follow-up cutting tool with interchangeable inserts (see variations of the disks).

By using the support washers ( Fig. 5 + 6, items 2 + 5), the pins on both sides of the toothed washers. Edge binding of the pins or rollers and one-sided bending is avoided by this connection. Another advantage of this connection is that all 10 or 14 pins have a supporting effect.

The stub axle with flange ( Fig. 5 + 6, item 1) is designed with the disc from an investment casting. The disc is so thin (∅ of the pin is the same wall thickness) that the holes can be made in one stroke with the same appropriately designed punching tool as the discs of the external gear. Furthermore, the same punching tool can be used to make the holes in the disks ( Fig. 5 + 6, items 2 + 5) and in the flange ( Fig. 5 + 6, item 8).

In conventional drum motors, the stator of the electric motor is shrunk into a tube. The tube is heated. The tube consists of either semi-finished products or an aluminum die-cast blank. Since the outside of the stator can only be manufactured with imprecision, the result is either eccentric positions (grinding of the rotor) or loose or badly inserted stator with assembly problems (reheating). Both solutions require expensive and problematic, accurate mechanical manufacturing. A solution has been found in the application, in which the tube receiving the stator is designed from a continuous cast profile ( FIG. 9). In the relaxed, extruded state, the cams of the profile are smaller than the outer diameter of the stator. The profile can be compressed by a device ( FIG. 8). Here, the inside diameter of the cams becomes larger, so that the stator can be inserted. If the device is relaxed, the profile springs back together and centers the stator of the electric motor ( FIG. 7). The profile is then screwed to the flanges ( Fig. 5 + 6, items 8 + 11). A large motor torque can be transmitted because a bead of the profile snaps into a groove in the stator.

A particularly easy cable assembly is possible if the cable is first led through the flange ( Fig. 5 + 6, item 11) and then the rotor with the ball bearing is mounted.

Since the bearing is placed inside the winding head of the electric motor and the cable between the flange and the bearing is also routed to the outside, a short version of 150 mm drum length ( Fig. 5) with large drum torques is possible. When extending the electric motor while maintaining all other dimensions, the same performances are achieved with a drum length of 200 mm as with current motors with a 300 mm drum length ( FIG. 6). The enclosed table for the lengths 150 mm and 200 mm shows the technical data of the drum motors. The enclosed brochures show a comparison with the technical data of the leading drum motor manufacturers. Here it becomes clear that the same maximum speeds and much lower minimum speeds are possible.

Reference list

1

Axle stub with flange

2nd

Support disc

3rd

Plastic teeth

4th

Perforated discs

5

Support disc

6

Eccentric disc

7

Stator sleeve

8th

Intermediate flange

9

Rotor ball bearing

10th

electric wire

11

Axle stub with flange

Claims (7)

1. Short design, characterized in that a coaxial, single-stage eccentric gear coupling gear ( Fig. 1) with a flat, convex on concave, with the same curvature involute toothing is used to reduce the engine speed. 2. Particularly inexpensive and accurate manufacture, characterized in that the gear ( Fig. 5 + 6, items 3 + 4) and the support discs ( Fig. 5 + 6, items 2 + 5) of the wheel coupling gear are composed of discs that can be produced with a stamping tool using the fine stamping process. 3. Particularly inexpensive and accurate manufacture of the flanges ( Fig. 5 + 6, items 1 + 8), characterized in that the flanges are designed so thin (hole ∅ = thickness) that the holes with the same punching tool as under claim 2 listed, can be introduced. 4. Short design, characterized in that the cable between the flange ( Fig. 5 + 6, item 11) and the rotor bearing is guided to the outside. 5. Short design, characterized in that the flange and stub ( Fig. 5 + 6, item 11) are designed in one piece as a precision casting to save space. 6. Inexpensive and low-noise design, thereby characterized in that the plastic teeth on the punched Slices of the core is injected and this on the holes the larger, inner discs clawed. 7. Inexpensive, without complex mechanical processing producible, easy to assemble stator receptacle, thereby characterized in that the stator receiving sleeve as Elastic extruded profile with cams to accommodate the Screws is running.