Electric servo actuators have many functions and are found in a variety of industrial applications. They are used to control positions, velocities or torques applied to various machine components. Typical applications include machine tools, packaging equipment as well as web processing equipment. Electric servo actuators are selected based upon the design parameters for a particular application. The design parameters that influence the selection process include the torque, rotational speed and power requirements. With respect to electric servo actuator design, it is well known in the art that power is proportional to the product of torque times rotational speed. Using this basic design principle, design engineers can modify the output torque from a servo motor by decreasing the servo motor's output rotational speed.
In practice, gear reducers are often used to convert the high rotational speed of servo motors into a higher torque, lower rotational output speed. Many types of gear reducers are available. One type of gear reducer is a planetary style reducer. This particular style of reducer uses a planetary arrangement of gears to apply a reduction ratio that is in an in-line (concentric) configuration. Planetary gear reducers are generally characterized by their small size, robustness, quiet operation, and low backlash. In typical applications, planetary gear reducers are made in modular form and are mounted to a standard servo motor to achieve the required speed reduction. FIG. 1 illustrates a typical design configuration having a servo motor 15 operably connected to a gear reducer 16. As shown in FIG. 1, adapter 17 is mounted to output shaft 18 of servo motor 15. Similarly, pinion 19 attaches to adapter 17 opposite servo motor 15. Gear reducer 16 receives as input pinion 19 and is selected to produce the desired output torque and rotational speed at shaft 20.
Conventional design configurations such as those exemplified in FIG. 1 have several shortcomings. For example, in situations where space and size are of concern, the addition of the components necessary to couple the servo motor with the gear reducer severely limits design options. Conventional configurations address this concern by using right angle gearheads and motors. However, this approach requires additional components and hence leads to a more expensive and heavier system.
Moreover, the conventional approach requires service personnel to manually couple the gear reducer to the servo motor. Often, this process requires special and proprietary mounting methods to fasten the gear reducer to the servo motor. Additionally, the process can result in improper installation or misalignment of the gear reducer with respect to the servo motor's output shaft. For example, if the modular gear reducer is not fastened to the servo motor properly, the strength of the pinion-shaft joint is weakened and can result in premature failure of the components.
Accordingly, there arises a need to provide for an electric servo actuator having substantially the same performance characteristics as a conventional motor and gearhead configuration but with the added feature of being very compact in relation to the conventional approach. Such an electric servo actuator and gearhead configuration would provide greater flexibility with respect to size and space considerations and substantially reduce installation and maintenance costs. The present invention addresses and overcomes the shortcomings of the prior art.