This invention relates to a shake system, which is intended for generating a shaking motion in a shake table, a shake plane, a shake pallet or the like, and in which shak- ing is generally used as a method in mixing systems of various types.

In shake systems, separate motors are typically used for generating linear and orbital shaking, or then one single motor is used with a connected separate gear box or change-over switch. Systems in which both linear and orbital shaking is generated with the aid of electro-magnetic coils are also used

The solutions mentioned above have, inter alia, the following drawbacks:

The number of motors, since one has to use two separate motors in order to achieve the motions, resulting in increased size and weight of the device and in higher production costs.

With the use of one single motor, the motor has to be "over-sized", resulting in increased physical size, power consumption etc. of the motor.

With the use of one single "normal-sized" motor, supplementary gear boxes or change-over switches are required, which, in turn, result in increased size, weight and cost of the construction.

Electro-magnetic coils merely generate a shake motion, but do not allow positioning of the shake table at the desired location. This also applies to separate X and Y plane solutions due to tolerances and to slack.

5. Linear shaking of a mobile plane is generated with the use of an eccentric control device attached to the shaft of the motor, the motion of the control device being limited by means of an opening, so that motion in one direction

(e.g. X direction) is restricted, whereas motion in the other direction (in this case e.g. Y direction) is allowed.

Orbital shaking of a mobile plane is generated by using two mutually perpendicular mobile planes and two eccentrics. The drawbacks of these solu- tions include wear of the parts, disturbing noise, especially at higher frequencies, and of high cost. The system described below achieves both linear and orbital shaking with the same stepping motor without any separate gear box or change-over switch. Consequently, the actuating means of linear shaking and orbital shaking will be mounted solidly on the same drive shaft of the motor, except for the balance weight, for which a free rotational motion around the drive shaft in question has been provided in the range required for linear shaking. The basic idea of the system is a crank lever mechanism, in which the performance of the motor is ensured during the use of different shake methods by altering the leverage relations. During orbital shaking, when lower performance is required of the motor, the leverage relations can be altered so that an orbital motion having the desired radius is generated at the desired rotational speed. During linear shaking, when higher performance is required of the motor, the leverage relations are altered in a way to decrease the demands on the motor and to attain the desired accelerations and motion distances.

The system has, inter alia, the following advantages:

1. A single-motor construction. Orbital motion is achieved when the motor rotates continuously in one direction. Linear motion results by having the motor rotate back and forth within a sector narrow enough not to move the counterweight. This solution requires less space, fewer motor controls, reduced cabling and the like. In addition, the construction requires but one single eccentric and one single mobile plane.

2. The size of the motor. The system does not call for an "over-sized" motor, hence the physical size, power consumption and similar features of the motor will consequently be small.

3. A straightforward and reliable construction. Owing to the lever mechanism, the motor and the power-transmission constructions will not be exposed to excessively strong forces. This enhances the reliability and the life span of the system. In addition, the system is practically maintenance- free.

4. Accuracy. The slack-free interconnection of the moving parts of the system allows accurate positioning of the plane.

5. The construction is as silent and wear reducing as possible, as the motion of the shake plane being the sum of the rotational motions of the different parts and the construction being free of slack.

The invention will be described below by means of an example and with reference to the accompanying drawings, which illustrate the principles of both linear and orbital shaking. THE PRINCIPLE OF LINEAR SHAKING:

The driving force for the shaking is provided by the stepping motor (7). A crank assembly (9) with a connecting rod (5) equipped with bearings is solidly mounted on the shaft of the stepping motor. One end of the connecting rod is connected to the shake table (1) through the intermediary of a bearing block (12). Before shaking starts, a linear actuator (10) locks the Y motion of the system by pushing a lock pin through the Y motion locking part (8) and a balance weight (4). This action prevents any motion of the shake table in the Y direction and any motion of the balance weight during linear shaking.

After the locking, the stepping motor moves into a position such that the crank arm

(2) is positioned approximately at the centre of the stop shoulders (4) of the balance weight. After this, the stepping motor starts rotating in a short reciprocating motion, whereby the connecting rod mounted eccentrically in the crank assembly starts actuating the shake table with a short reciprocating motion in the X direction.

THE PRINCIPLE OF ORBITAL SHAKING: The driving force for the shaking is provided by the stepping motor (7). A crank assembly (9) with a connecting rod (5) equipped with bearings is solidly mounted on the shaft of the stepping motor. One end of the connecting rod is connected to the shake table (1) through the intermediary of a bearing block (12). When the stepping motor starts rotating clockwise (in this implementation version), the stop shoulder (11) in the crank assembly moves against the connecting rod, whereby the axis of the connecting rod pointing towards the shake table starts rotating with a radius of 12.5 mm (in this implementation version), thus entailing the same motion in the shake table mounted on bearings in linear guide bars (6). Any vibrations caused by the shaking are eliminated by the pivoted balance weight

(3) . As shaking starts, the crank arm (2) attached to the crank assembly is pressed against the stop shoulder (4) of the balance weight, thus forcing the stop shoulder to rotate along with the crank arm. These structural solutions yield the advantage of a device devoid of mutually mobile parts, since movement is generated by a combination of rotational motions of pivoted parts.