DE29710762U1 - Device for determining the speed and / or direction of rotation of an electric motor - Google Patents

Description

TER MEER STEINMEISTER & PARTNER GBR

PATENT ATTORNEYS - EUROPEAN PATENT ATTORNEYS

Dr. Nicolaus ter Meer, Dipl.-Chem. Helmut Steinmeister, Dipl.-Ing,

Peter Urner, Dipl.-Phys, Manfred Wiebusch

Gebhard Merkie, Dipl.-Ing. (FH)

Mauerkircherstrasse 45 Artur-Ladebeck-Strasse

D-81679 MUNICH D-33617 BIELEFELD

St/bf. 14.5.1997

HANNING ELECTRICAL WORKS

GmbH & Co.

Holter Str. 90

33813 Oerlinghausen

DEVICE FOR DETERMINING THE SPEED AND/OR DIRECTION OF ROTATION OF AN ELECTRIC MOTOR

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DEVICE FOR DETERMINING THE SPEED AND/OR DIRECTION OF ROTATION OF AN ELECTRIC MOTOR

The invention relates to a device for determining the speed and/or direction of rotation of an electric motor enclosed by a housing, with a magnet attached to an end region of the shaft of the electric motor and a Hall sensor attached opposite the magnet outside or next to the orbit of the magnet.

The use of a Hall sensor or Hall generator to determine the speed and direction of rotation of the rotor of an electric motor is well known. A magnet that rotates with the rotation of the shaft is attached to the shaft of the electric motor and generates a Hall voltage in a Hall sensor opposite the magnet's orbit. The Hall voltage can be evaluated to determine the speed and direction of rotation using a downstream peripheral.

Since the voltage generated in the Hall sensor depends, among other things, on the strength of the magnetic field of the magnet penetrating it, but the magnet used generally has only a weak magnetic field, the magnet and the Hall sensor are arranged only a short distance from each other. The Hall sensor must therefore be positioned relatively precisely within the motor housing. A suitable holder is therefore necessary that fixes the Hall sensor very precisely in a predetermined position and does not allow the Hall sensor to move in any way, even after prolonged use, at high temperatures and when subjected to vibrations.

The object of the invention is therefore to create a device of the type mentioned at the outset, in which the assembly of the Hall sensor is simplified.

This object is achieved according to the invention in a device of the above type in that a window penetrating the front wall of the housing is provided and that the Hall sensor is held in a pocket which can be inserted into the window and locked into place therein.

By accommodating the Hall sensor in a pocket that can be inserted into a window in the engine’s bulkhead, the Hall sensor is not only securely

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held, but also protected, and the window and the pocket can be adjusted in relation to each other in such a way that the pocket can be easily snapped into place and is located exactly in the specified position. The window can also be used to lead the connection cables of the Hall sensor out of the motor housing.

It is naturally particularly useful to design the pocket in such a way that it can be inserted into the window from the outside of the housing. In this case, the Hall sensor can be installed when the rest of the motor assembly is finished, so that there is no longer any risk of the Hall sensor being damaged or displaced by the assembly work. The Hall sensor also remains accessible from the outside, making it easier to eliminate malfunctions and carry out repairs. By choosing the right position of the sensor in the pocket and the corresponding dimensions of the pocket and window, it is easy to ensure that the Hall sensor automatically reaches the specified position in relation to the magnet inside the housing.

The bag is preferably made of a flexible plastic. The bag is made of a lower part and an upper part that is connected to the lower part in a hinged manner, for example with the help of a film hinge, and can be locked into place. The bag can have the shape of an elongated, flat cuboid, and the cross-section of the window is adapted to the cross-section of the bag.
25

The pocket is preferably secured in the window using spring-loaded tongues on the opposite long sides of the pocket, which extend from a connecting area parallel to and at a distance from the long sides of the pocket and have projecting hooks at both ends which grip the front wall of the housing, usually a bearing plate, from the inner surface and the outer surface. To remove the pocket from the window, the spring-loaded tongues can be pressed together by hand.

To accommodate the Hall sensor, a recessed chamber is preferably provided at the long end of the lower part, opposite which, when the pocket is closed, is a protruding pressure surface at the free end of the upper part.

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through which the Hall sensor is reliably held and positioned in the chamber. A cable passage is preferably formed in the connection area between the lower part and the upper part, i.e. the film hinge.

On the inner surfaces of the upper and lower parts there are transverse ribs, which are opposite each other when the bag is closed, to form a strain relief for the cable connected to the Hall sensor and leading out of the bag.

On the long sides of the lower part there are preferably upright side walls. The width of the springy tongues can take up the entire height of the closed bag. On the inner surfaces of the side walls and on the outer side surfaces of the upper part there are corresponding, longitudinal ribs or grooves which are arranged in such a way that when the bag is closed the ribs can be locked together. In this way the upper and lower parts can be connected to each other. This purpose is also served by a locking hook on the free end of the upper part which can be locked behind the free end of the lower part when the bag is closed.

A longitudinal, protruding support rib is preferably formed on the outside of the upper part, by which the pocket and thus the Hall sensor are supported in a defined position within the window.

The magnet can preferably be ring-shaped and attached to a silicone ring that is pushed onto the shaft. If the silicone ring is slightly undersized in relation to the shaft diameter and slightly oversized in relation to the inner diameter of the ring-shaped magnet, additional fastening means for determining the arrangement of the silicone ring and magnet on the shaft are not required. The assembly can therefore be carried out easily and reliably.

In the following, preferred embodiments of the invention are explained in more detail with reference to the accompanying drawings:

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Fig. 1 is a vertical section through an electric motor

with the features of the present invention;

Fig. 2 is a left view of Fig. 1;

Fig. 3 is a side view of a pocket for receiving a

nes Hall sensor;

Fig. 4 is a corresponding, partially sectioned illustration

position;

Fig. 5 is a plan view of the opened bag,

Fig. 6 corresponds to Fig. 5, but shows an alternative embodiment.

shape of the bag.

Fig. 1 shows a vertical section through an electric motor to which the present invention can be applied. The electric motor has a housing 10 which essentially consists of a front bearing plate 12, a rear bearing plate 14 and an intermediate piece (not shown). The bearing plates are connected by means of tie rods 16. Four arms 18 extend from the rear bearing plate in a star-shaped arrangement (Fig. 2), which serve to fasten the electric motor to a base (not shown). The shaft 24 of the motor is mounted in the two bearing plates 12, 14 by means of ball bearings 20, 22. On the section 26 of the shaft 24 protruding to the right in Fig. 1 from the front bearing plate 12, a fan wheel 28 is indicated in dash-dotted lines as an example of a driven part. The power supply and control cables of the motor are designated by 30. Immediately adjacent to the front bearing plate 12, on the shaft 24 there is a motor-specific fan wheel 32 for cooling the motor.

Further details of the electric motor as a whole will not be discussed here, as it is a conventional design. The special feature of the invention lies in the arrangement of a device for determining the direction of rotation and/or speed of the motor with the aid of a Hall sensor. This arrangement essentially comprises an annular magnet 34 mounted on the shaft 24 and a

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Hall sensor 36 arranged opposite the circumference of the magnet. The Hall sensor 36 is located in a plastic pocket 38 which is inserted into a window of the bearing plate 14.

This window, designated 40, can be seen in particular in the view of the bearing plate 14 in Fig. 2. Like the pocket 38, it has a flat rectangular cross-section. Fig. 2 also shows a connecting cable 42 extending from the Hall sensor, which transmits the sensor signals for evaluation. In Fig. 1 it can be seen that the pocket 38 can be positioned in the window 40 in such a way that the Hall sensor 36 is opposite the circumference or orbit of the ring-shaped magnet 34. For this purpose, the pocket 38 on the one hand and the window 40 on the other hand are shaped in such a way that the pocket 38 automatically locks into the predetermined position when pushed into the window from the outside. Locking elements are formed on the pocket 38, which enable locking, as will be explained in more detail below with reference to Figs. 3 to 6.

According to Fig. 3 to 6, the bag consists of a lower part 44 and an upper part 46, which in the example shown are made of plastic and are connected via a film hinge 48.

At the free end of the lower part 44 of the pocket 38, which is on the right-hand side in Fig. 3 to 6, a recessed chamber 50 is formed, which serves to accommodate the Hall sensor (not shown). When the upper part 46 is folded onto the lower part 44, there is a raised pressure surface 52 above the chamber 50, which lies above the chamber 50 and additionally holds the Hall sensor in place. Three branched cable ducts 54, 56, 58 extend from the chamber 50 to accommodate the connecting wires of the Hall sensor (not shown). At the end of the cable ducts 54, 56, 58, there are transverse ribs 60 and 62 on the surface of the lower part 44 and on the corresponding surface of the upper part 46, which clamp the connecting cable or cables when the pocket is closed and thus serve as strain relief. In the area of the film hinge 48 there is a cable passage 64 which partially enters the upper part 46, through which the connecting cable 42 can exit from the pocket 38 and thus at the same time from the bearing plate 14 of the motor, as shown in Fig. 2.

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On some of the long sides of the lower part 44 there are upstanding side walls 66, 68, between which the upper part 46 enters when the pocket is closed. On the long sides of the upper part 46 there are protruding ribs 70, 72, which engage in grooves 74 on the inner surfaces of the side walls 66, 68 when the pocket is closed. A hook 76 protruding from the free end of the upper part 46 is also used to close the pocket. The hook engages over the free end of the lower part 44 and has a bead-shaped projection 78 at its end, which enters a bevel 80 on the lower edge of the free end of the lower part 44 (Fig. 3). The interaction of these locking parts closes the pocket tightly, and the interaction of the chamber 50 and the pressure surface 52 on the lower and upper parts ensures that the Hall sensor is precisely positioned and held within the pocket.

Spring tongues 82,84, which are formed on both long sides of the lower part, serve to lock the pocket 38 in the window 40. These spring tongues extend from a connecting area 86,88, which connects the spring tongues 82,84 to the side walls 66,68. From this connecting area 86,88, the spring tongues 82,84 extend essentially parallel and at a distance along the side walls 66,68. The spring tongues 82,84 are higher or, in relation to their longitudinal extent, wider than the side walls 66,68, so that their height essentially corresponds to the height of the closed pocket. They have hooks 90, 92 and 94, 96 at both ends that protrude outwards and are bevelled from the ends and rest against the inner and outer surfaces of the bearing plate 14 on both sides of the window 40. Since the spring tongues are elastically deformable when a suitable plastic is selected, the pocket can be reliably held in the window 40 with the help of the spreading forces of the spring tongues 82, 84.

In the case of the pocket shown in Fig. 5, the spring tongues 82, 84 point to the left, i.e. from the chamber 50 of the Hall sensor in the direction of the cable passage 64. This means that the embodiment according to Fig. 5 is intended for the installation of the Hall sensor from the inside of the housing. During installation, the connecting cable (not shown in Fig. 5) is first guided out through the window in the front wall of the housing, in particular a bearing plate, and then the spring tongues 82, 84 are pulled out with the fingers.

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pressed together until they can enter the window opening. After the pocket has been pushed in, the spreading forces of the spring tongues 82,84 ensure that it is securely fastened, even when the engine is running for a long time and when vibrations occur.

In the embodiment according to Fig. 6, the spring tongues marked 102, 104 are directed in opposite directions, i.e. from left to right in the drawing. Therefore, the embodiment according to Fig. 6 is suitable for mounting the pocket and thus the Hall sensor from the outside of the housing.

Here too, the spring tongues 102, 104 are first pressed together with the fingers so that they can enter the window. The area of the pocket in which the Hall sensor is located enters the interior of the motor housing through the front wall. The connecting cable extends outwards through the cable opening 64, as shown in Fig. 2.

It is obvious that the embodiment according to Fig. 6 is to be regarded as particularly preferred, although the embodiment according to Fig. 5 also offers considerable advantages when mounting the Hall sensor.

In Fig. 3 and 4 it can be seen that the upper part 46 has a longitudinally directed, projecting support rib 98 on the outside. This support rib 98 serves to support the upper part 46 and thus the pocket and the Hall sensor 36 in the window 40, as can be seen in Fig. 1. The support rib 98 thus prevents the Hall sensor 36 from deviating from the orbit of the magnet 34, since too great a distance of the Hall sensor 36 from the magnetic field of the magnet 34 would impair the intended function or even make it impossible.

The ring-shaped magnet is attached to the shaft 24 by means of an elastic ring 100, in particular made of silicone. The ring has in particular an inner diameter that is slightly smaller than the outer diameter of the shaft and an outer diameter that is slightly smaller than the inner diameter of the ring-shaped magnet 34. In this way, the magnet 34 can be attached to the shaft 24 very easily and yet securely.

Claims (16)

TERMEER STEINMEISTER & PARTNER QhFi I * I I V I flanhUg telektro-Werke PROTECTION CLAIMS 1. Device for determining the speed and/or direction of rotation of an electric motor enclosed in a housing, with a magnet (34) attached to an end region of the shaft (24) of the electric motor and a Hall sensor (34) attached outside or next to the orbit of the magnet opposite the latter, characterized in that a window (40) penetrating the end wall of the housing is provided, and that the Hall sensor (36) is held in a pocket (38) which can be inserted into the window (40) and locked in the window. 2. Device according to claim 1, characterized in that the pocket (38) consists of a flexible plastic. 3. Device according to claim 2, characterized in that the pocket (38) consists of a lower part (44) and an upper part (46) which is connected to the lower part in a hinge-like manner and can be locked to the lower part. 4. Device according to one of the preceding claims , characterized in that the pocket (38) has the overall shape of an elongated, flat cuboid and that the window (40) has a cross section corresponding to the cross section of the cuboid. 5. Device according to claim 4, characterized in that spring tongues (82, 84) are formed on the opposite longitudinal sides of the pocket (38), which extend from a connecting region (86, 88) essentially parallel to and at a distance from the longitudinal sides and have outwardly projecting hooks (90, 92, 94, 96) at both ends. 6. Device according to one of claims 2 to 5, characterized in that the lower part (44) and the upper part (46) are connected by a film hinge (48). 7. Device according to one of claims 3 to 6, characterized in that a chamber (50) for receiving the Hall sensor (36) is provided at the free end of the lower part (44). TERMEER STEINMEISTER & PARTNER ®kFi &idigr;*&iacgr;&iacgr;&idigr;&idigr; rfaimlsg felektro-Werke 8. Device according to claim 7, characterized in that a projecting pressure surface (52) is formed at the free end of the upper part (46) in the position corresponding to the chamber (50). 9. Device according to one of claims 6 to 8, characterized in that a cable (64) is formed in the film hinge (48). 10. Device according to claim 9, characterized in that transverse ribs (60, 62) are formed on the inner surfaces of the upper part (46) and lower part (44) and lie opposite one another when the pocket (38) is closed. 11. Device according to one of claims 5 to 10, characterized in that upstanding side walls (66, 68) are formed on the longitudinal sides of the lower part (44). 12. Device according to claim 11, characterized in that corresponding, longitudinally directed ribs and/or grooves 70, 72, 74 are formed on the inner surfaces of the side walls (66, 68) and on the side surfaces of the upper part (46), which are arranged in such a way that they engage with one another when the pocket is closed. 13. Device according to one of claims 3 to 12, characterized in that a locking hook (76) is formed on the free end of the upper part (46), which can be locked behind the free end of the lower part (44) when the bag is closed. 14. Device according to one of claims 3 to 13, characterized in that a projecting, longitudinally directed support rib (90) is formed on the outer surface of the upper part (46). 15. Device according to one of claims 5 to 14, characterized in that the width of the spring tongues (82,84) corresponds substantially to the height of the closed pocket. TERMEER STEINMEISTER & PARTNER .©ßri.. ^: * ·,,' ^: . _# ^: Haiming fclektro-Werke 16. Device according to one of the preceding claims, characterized in that the magnet (34) is ring-shaped and that the magnet is mounted on the shaft (24) via a silicone ring (92), the inner and outer diameter of which is slightly undersized or oversized in relation to the shaft and the magnet.