HK1030980B - Self-centering encoder disc hub and method for mounting the same - Google Patents

Description

The invention relates to a self-centering clock face with a clock face (1a) and a tubular hub (1b) which is slit at least in the area of the motor shaft W and the shaft of which is adjustable to a motor shaft, whereby a contact surface is created in the hub between the inner wall of the hub and the motor shaft.

Self-centering clock discs of the type mentioned at the outset are known from the DE 196 41 929 A1 (RUHLATEC Industrieprodukte GmbH).

EP 046 81 47 shows a fixing for the fan wheel of a blower on a drive shaft made of a difficult to work material such as a ceramic material. This is done by using a continuously slit hub in the form of a casing that carries an external wind which is screwed over a tubular mother.

According to GB 1241455, clamping rings are fixed on the end of a shaft using a clamping device with a clamping backing. The clamping backings have protrusions to secure the clamping rings. When a clamping ring is moved, the clamping backings are compressed, thus fixing the rings on the end of the shaft.

When mounting crankshaft shafts on a side of the engine, care must be taken to ensure that there is sufficient clearance for centering on the motor shaft. Therefore, the crankshaft shaft has a catch hole at its end facing the engine to align the vertical axes of shaft and crankshaft. When the shaft is pushed into the crankshaft shaft, a compression occurs because the diameter narrowed shaft is pressed on the finely machined shaft. The axial pressure is applied to the top of the housing surface on the crankshaft surface and brings this and the associated crankshaft shaft into the correct position for a crankcase arrangement.

The use of such clock discs is increasing, so that in the meantime very high quantities are being produced. This is a problem, especially in mass production, due to the high requirements for the surface quality of the motor shaft and clock face, or the manufacturing accuracy to meet the required tolerances.

The present invention is therefore intended to produce a clock face with self-centering properties which can be mounted, adjusted and secured to a motor shaft without pre-tensioning, and which can be assembled under mass production conditions with the precision required for encoders.

The problem is solved by the features given in claims 1 and 8. it has been shown that a shaft shaft shaft designed in accordance with the invention can be pushed up and tensioned on the motor shaft simultaneously with the mounting motion without the mounting motion causing the axis of the shaft shaft to shift to the motor shaft. the forces required for mounting are very small as no press seats are produced but the shaft and shaft are slid on each other during mounting and then fixed together.

The following is a detailed description of the invention using several examples.

It shows: Figure 1 Cross section of a clock face of the invention before installation,Figure 2 Cross section of a clock face of the invention after installation on a motor shaft,Figure 3 Principle sketch to explain the assembly process,Figure 4 View of BB from the side of the motor shaft connection,Figure 5 Enlarged section A from Figure 4,Figure 6 Pre-assembled housing according to DE 196 41 921 A1.

The disc face of the disc, according to the invention, is shown in Figure 1 with a disc face 1a and a tube face 1b in cross-section. The outer wall of the face 1b is conical in shape, the angle of the cone rising from the shaft E to the disc face 1a. In the face 1 slits are formed which extend to the contact area with the motor shaft W (Figure 2).

At the end of the hub 1b, a contact surface 1c is formed to give a clamping element S a secure hold in the resting position before mounting.

The crankshaft shaft is shown in Figure 2 after mounting on the motor shaft W. It is shown that the crankshaft 2 has advanced to its crankshaft position on the conical outer wall of the shaft 1b. It is held in the forward position (crankshaft position) on a resting surface 3 and in this position ensures a slip-free, force-tight connection between shaft and crankshaft shaft.

Figure 3 shows the assembly process schematically. By moving the clock face 1b to a shaft W, the tension ring 2 is pushed from its front position to the cone, so that a tension is applied to the shaft W. Since the shaft is made of plastic, preferably ABS, even small tension forces are sufficient to enable the clock face to be securely held on shaft B. This is shown in Figure 4, viewed from the motor shaft side.

The slit width is preferably larger than the wall thickness of the tubular clock face. At least four slits evenly distributed over the tube circumference of the clock face result in a relatively elastic body that can be brought into close contact with the W shaft by low external pressures. Figure 4 shows how the tension ring is pushed from the rest position (light grey area H) to the tensioned position (dark area D).

At the same time, the clamping ring must be securely held on the crankshaft hub in both positions. In the enlarged section A shown in Figure 5, it is shown that the shaft 1c holds the clamping ring securely on the hub in the resting position.

For comparison with a clock face according to the state of the art and to explain the installation situation, a cross-section of a pre-mounted encoder is shown in Figure 6.

At the top of the hub 9 a centrifugal surface 17 is formed which allows automatic centrifugation in connection with the conductive surface of the housing 16.

The known encoder unit can also be used for the purposes of the present invention, provided that the clock face 9 is replaced by a clock face designed in accordance with the invention.

The test method of the invention has been demonstrated to allow the axis of the clock face to be precisely aligned with the axis of the motor shaft. This has resulted in low mounting forces, so that no bending stresses can be transferred to the clock face. The design of the restraint for the safety ring ensures that the clock face is permanently fixed to the clock face. Furthermore, tests with various materials have shown that clock faces manufactured according to the invention have an excellent fit-to-fit seat even when the motor shaft can only have a reduced surface area.

Claims (8)

1. A self-centring encoder disc hub having an encoder disc supporting face (1a) and a tubular hub shank (1b) which is slotted at least in the region of the motor shaft (W) and whose shank end can be slid on to a motor shaft, wherein, in the hub shank, there is obtained a contact face between the inner wall of the hub shank and the engine shaft, characterised in that the outer wall of the hub shank (1b) is at least partially conical and comprises a cone angle which rises from the shank end (E) to the encoder disc supporting face (1a); that at the shank end (E), on the outer wall, there is displaceably arranged a tensioning element provided in the form of a tensioning ring (2) consisting of an elastic plastic material, that the hub shank (1b), on the outer wall in the region of the open end of the slot, comprises an abutment face (1c) for the resting position of the tensioning element and that in the first third of the hub shank (1 b) - if viewed from the motor shaft end - there is worked in an engagement face (3) on the outer circumference of the hub shank for the tensioning position of the tensioning element.
2. A self-centring encoder disc hub according to claim 1, characterised in that the cone angle ranges between 10 and 15°.
3. A self-centring encode disc hub according to any one of the preceding claims, characterised in that the length of the slot in the hub shank (1b) ranges between 0.5 and 0.8 of the contact face of the hub shank/motor shaft.
4. A self-centring encoder disc hub according to any one of the preceding claims, characterised in that the width of the slot ranges between 1 and 2 mm.
5. A self-centring encoder disc hub according to any one of the preceding claims, characterised in that the engagement face comprises a bead-shaped raised portion (3a) on the outer circumference of the hub shank.
6. A self-centring encoder disc hub according to any one of the preceding claims, characterised in that at the shank end facing the motor shaft, the inner wall of the hub shank (1b) is widened conically.
7. A self-centring encoder disc hub according to any one of the preceding claims, characterised in that the conical widening at the inner wall of the hub shank extends from the end face as a far as a region of 20 % of the hub shank length.
8. A method of mounting a self-centring, slotted encoder disc hub on a shaft, more particularly a motor shaft of a slotted encoder, wherein the encoder disc hub is provided with an encoder supporting face (1a) and with a tubular hub shank (1b) whose shank end points towards the motor shaft, characterised in that the outer wall of the hub shank (1b) is at least partially conical and comprises a cone angle which rises from the shank end (E) to the encoder disc supporting face (1a); that at the shank end (E), on the outer wall, there is displaceably arranged a tensioning element provided in the form of a tensioning ring (2) consisting of an elastic plastic material, that the hub shank (1 b), on the outer wall in the region of the open end of the slot, comprises an abutment face (1c) for the resting position of the tensioning element, wherein in the first third of the hub shank (1b) - if viewed from the motor shaft end - there is worked in an engagement face (3) on the outer circumference of the hub shank for the tensioning position of the tensioning element; and that when pressing the encoder disc hub on to the motor shaft, the tensioning ring is displaced from an untensioned into a tensioned position.