Electric Blender

The invention relates to an electric household blender having a removable container, in which motor-driven winged blades rotate and having a motor base with an electric operating switch.

In known apparatus of this type it often occurs, particularly when a low-density material is to be processed in the container, that the rotor of the motor continues to rotate for several seconds after being turned off. If the user is not careful there is a danger of severe injury if the user places his hand into the container before the blades have completely stopped rotating.

In order to protect the user of a household blender from this type of injury, it has already been proposed in German Pat. No. 2,228,189 to close the control circuit of a brake device of the motor as soon as the lid is removed from the container. For this purpose the electrical circuit of the drive motor includes one or more switches connected in series, whose movable switch element can assume either an operating position in which the electrical circuit is closed, or a rest position in which this electrical circuit is open. The movable switch element of at least one switch has at least one contact, which, when in the rest position, closes the control circuit of the brake device of the motor. Turning the blender on by moving the switch out of the brake position is effected by pressing the lid against the container. This known household blender has the disadvantage that the user must continually press downward on the lid of the device and can thus not leave the device while it is in operation. Furthermore, the known household blender cannot be combined with auxiliary units, such as a mixing unit, citrus press or meat grinder, because these auxiliary units require a firm anchor to the motor base.

The objective of the present invention is to create an electric household blender, in which after the motor is turned off all danger of injury from still-rotating blades is eliminated and which allows the addition of auxiliary units. The apparatus is to be formed in such a manner that the user of the blender need not remain next to the apparatus during its operation.

This objective is achieved according to the invention in that the container is held by a container holder with lock bolt supports which can be placed on the motor base and which can be locked with lock bolts by means of a locking ring. For this purpose the locking ring--which is held and guided in the motor base, is rotatable about the longitudinal axis of the motor base and can be moved by a lock bolt cooperating with a lock rod which can be moved longitudinally in the motor base, and which in turn releases or locks the operating switch for turning the motor on and off, depending on the position of the locking ring.

The motor base and container holder are advantageously provided with guide surfaces, whereby the container holder has lock openings or slots in the vicinity of the guide surfaces as lock bolt supports, in which lock bolts or studs engage. These lock bolts or studs are arranged on the movable lock ring and are supported and guided in openings in the housing of the motor base.

The container holder is advantageously provided with guide surfaces, at least two of which are arranged so as to be distributed about the circumferential surface, whereby each locking pocket is provided with a locking groove or locking slot and the locking pockets are enclosed in corresponding depressions equipped with guide surfaces, which are provided on the motor base.

The measures according to the invention assure that the apparatus can be turned on only when the container for the material to be blended or an auxiliary unit is placed on the motor base and is rigidly locked thereto. The unlocking procedure and subsequent removal of the container holder requires sufficient time to ensure that the motor will have stopped before contact with the tools or blades is possible.

The invention allows a wide variety of possible embodiments. One of these is schematically illustrated in the attached drawings, wherein:

FIGS. 1 and 2 show an electric household blender in perspective view, with the holder for the container for receiving the material to be blended being separated from the motor base,

FIG. 3 shows a partial section through the blender, whereby the device for locking the container holder, part of the container and the container locked by the container holder are shown in section. The motor and wing blades are not depicted for better visibility,

FIG. 4 shows a perspective partial illustration of the container holder with interlocking pocket,

FIG. 5 shows a perspective partial illustration of the motor base, and

FIGS. 6 and 7 show a schematic and perspective illustration of the basic parts of the device for locking the container holder to the motor base.

The container 1, together with the lid 10, is held by a holder 2 between the edge 20 of the holder 2 on one side and the motor base 4 on the other side. In order to lock the container to the motor base 4, the holder 2 has three interlocking pockets 5 with guide surfaces 35, 36, 37 uniformly distributed about its circumference. These guide surfaces are provided with respective perpendicular projections 7 and a lock bolt support 12 (FIG. 4). When the holder 2 is placed on the motor base 4 the projections 7 move in the direction of arrow A (FIG. 4) and press against the lock bolts 8, three of which are distributed about the circumference of a lock ring 9 arranged on the inside of the motor base, and thus make the interlocking mechanism (shown in FIGS. 6 and 7) capable of operation.

After mounting the holder 2 and moving it in the direction of arrow A, the lock ring 9, which is movably mounted in the motor base (FIG. 6) is pushed by the projections 7 against the force of springs. If the lock ring 9 is then rotated in the direction of arrow C by the lock bar 11 via the external projection of the latter on the outside of the motor housing, the lock bolt 8 moves into the lock bolt support 12 (FIG. 7). The horizontally arranged lock bolts 8 are held and guided for this purpose in long L-shaped openings 13 cut in the housing wall of the motor base 4. The lock ring 9 also has three longitudinal holes 17 distributed about its circumference, and screws 14 with springs 16 pass through each of these longitudinal holes, the screws being attached at 15 to the motor base 4. The springs 16 press the lock ring 9 upward opposite the direction of arrow A.

On the outside wall of the motor base 4 in the area of the L-shaped longitudinal holes 13, downwardly open guide brackets 30 (FIG. 5) with bores 28 are provided for the projections 7, so that the projections of the interlocking pockets 5 exactly meet the lock bolts 8 of the lock ring 9 when the holder 2 is placed on the motor base. As shown in FIGS. 6 and 7, the lock ring 9 can be moved in the direction of arrows C or D with the aid of the lock bar 11, which is guided in a longitudinal hole, not shown in detail, in the housing wall of the motor base.

In addition to a carrier 24, which is enclosed in a fork 43 of the lock ring 9, the lock bar 11 also has a lock fork 25, which acts together with the lock rod 26, which can be moved perpendicularly thereto in the motor base 4, and which, in turn, is engaged by the stud 38 of the operating switch. When the lock ring is in the position shown in FIG. 7, i.e., when the holder 2 is locked by the bolts 8 and the lock bolt supports 12 after the lock bar 11 is moved in arrow direction C, the lock rod 26 can be moved vertically upward in the direction of arrow E by rotating the operating switch 27 in the direction of arrow G, so that the lock rod 26 enters into the recess 29 of the lock fork 25. Only in this position (FIG. 7) can the operating switch 27 be rotated and the motor be turned on to drive the blades. If the operating switch 27 is rotated opposite the direction of arrow G, the lock rod 26 moves vertically downward opposite the direction of arrow E, so that the lock bar 11 can be moved in the direction of arrow D. After the lock bar is moved in the direction of arrow D (FIG. 6) the lock rod 26 is blocked, because one end thereof abuts the sides of the lock fork 25, which renders the operating switch 27 incapable of rotation.

The exemplary embodiment of the holder 2 shown in FIG. 3 is not only suited to hold a lid on a container and lock both parts (10 and 1) to the motor base 4, but rather the container 1 with lid 10 can be exchanged for a mixing unit, a meat grinder or a citrus press. These types of auxiliary units require only a base portion which corresponds in diameter d and height h (FIG. 3) to the illustrated container 1 and lid 10. Because the container holder 2 is provided on its upper side with an opening o, parts of the auxiliary units can be formed in such a manner that they project far beyond the holder 2. Finally, holders can be provided whose dimensions h and o are such that--for example with a mixing unit--it is impossible for the user to reach the rotating blades with the hand or fingers through the top opening. The inner surfaces of the container holder are effectively provided with ribs, cams of the like (not shown), which reliably prevent the container holder or the auxiliary unit from rotating about the blade axis when the motor is turned on. The electrical control portion in the motor base is also provided with a known braking device; thus when the motor is turned off the control circuit of a braking device is closed so that the motor instantaneously comes to a halt. Instead of an electrically operating braking device, the lock bar 26 can also be coupled with a mechanically operating motor brake. As soon as the lock bar moves in the opposite direction from arrow E--i.e. when the motor is turned off--it presses a brake shoe against the motor shaft.