Industrial robot with a weight counterbalance system

Abstract

The invention relates to an industrial robot (1) having a robot arm (2) with a plurality of axes (9, 10) designed for a high payload and having a weight equalization system (12) based on gas for at least one of the axes (9), whose pressurized components (13-15) each have a volume of less than 1 liter and a maximum pressure of less than 1000 bar.

Claims

1. An industrial robot, comprising: a robot arm having a plurality of articulation axes; and a pressurized gas-based weight equalization system operatively coupled with the robot arm, the weight equalization system comprising pressurizable components and operable to react to forces applied to the robot arm for offsetting a load supported thereon: the pressurizable components each having a volume capacity less than 1 liter (61.0 cubic inches), and a maximum pressure capacity less than 1000 bar (14.5 kpsi); wherein the weight equalization system comprises: a pressure cylinder; and at least two pressure accumulators, each operatively coupled with the pressure cylinder.

2. The industrial robot of claim 1, wherein the pressurizable components have a maximum pressure capacity of 400 bar (5.80 kpsi).

3. The industrial robot of claim 1, wherein the pressurizable components have a maximum pressure capacity of 350 bar (5.08 kpsi).

4. The industrial robot of claim 1, wherein the pressurizable components have a maximum pressure capacity of 300 bar (4.35 kpsi).

5. The industrial robot of claim 1, wherein the robot arm comprises: a carousel; and a rocker supported on the carousel and having a pivot axis about which the rocker moves; wherein the weight equalization system reacts to forces applied to the rocker in response to movement of the rocker about the pivot axis.

6. The industrial robot of claim 5, wherein the weight equalization system is supported on the carousel by a single bearing.

7. The industrial robot of claim 5, wherein the weight equalization system is one of a gas system that uses only pressurized gas as the working fluid, or a hydropneumatic system that uses gas and liquid as the working fluid.

8. The industrial robot of claim 1, wherein the robot arm has a maximum payload capacity greater than 80 kg (176.4 pounds).

9. The industrial robot of claim 1, wherein the robot arm has a maximum payload capacity greater than 90 kg (198.4 pounds).

Description

(1) An example of an exemplary embodiment of the invention is depicted in the attached schematic drawings. The figures show the following:

(2) FIG. 1 an industrial robot having a weight equalization system, and

(3) FIG. 2 the weight equalization system.

(4) FIG. 1 shows a side view of an industrial robot 1 having a robot arm 2 which is designed for large payloads, in particular greater than 90 kg.

(5) In the case of the present exemplary embodiment, robot arm 2 includes a stationary or movable base 3 und a carousel 5 that is supported so that it is rotatable relative to base 3 around a vertical axis 4, which is also referred to as axis 1. In the case of the present exemplary embodiment, robot arm 2 of industrial robot 1 also has a rocker 6, an extension arm 7 and a preferably multiaxial robot hand 8. Rocker 6 is mounted at the lower end on carousel 5, for example on a swivel bearing head that is not shown in further detail, so that it can swivel around a preferably horizontal axis 9, which is also referred to as axis 2. At the upper end of rocker 6, extension arm 7 in turn is mounted so that it can swivel around a likewise preferably horizontal axis 10. This extension arm carries at its end robot hand 8 with its preferably three axes, which are not shown in further detail in FIG. 1.

(6) In order to move industrial robot 1 or its robot arm 2, the latter includes drives, in particular electric drives, that are connected in a generally known way to a control device 10, which is not shown in further detail. Only some of the electric motors 11 of these drives are shown in FIG. 1.

(7) The dynamic and/or static loads that act on rocker 6 during operation of industrial robot 1 due to the payload, the extension arm 6 [Translator's note: This should apparently be 7 rather than 6.], etc., are at least largely compensated for in the case of the present exemplary embodiment by a weight equalization system 12 based on gas which is shown in greater detail in FIG. 2. Weight equalization system 12 is in particular a gas weight equalization system, or a hydropneumatic weight equalization system, as is the case in the present exemplary embodiment.

(8) In the case of the present exemplary embodiment, weight equalization system 12 has a hydraulic cylinder 13 and two pressure accumulators 14, 15 which are connected to hydraulic cylinder 13. Pressure accumulators 14, 15 are fastened for example to hydraulic cylinder 13, and are connected to the latter by a connecting line.

(9) In each of pressure accumulators 14, 15 is a pre-pressurized gas bubble, not shown in greater detail, which presses for example on an oil cushion and produces the counterforces to compensate for the loads on the rocker. The pressure of each of the two pressure accumulators 14, 15 is chosen so that there are always lower than 400 bar, in particular lower than 350 bar and preferably lower than 300 bar, even at extreme positions of robot arm 2 and at elevated ambient temperatures. Furthermore, the two pressure accumulators 14, 15 are designed so that their volumes which are provided for the respective gas bubble are smaller than 1 liter.

(10) In the case of the present exemplary embodiment, hydraulic cylinder 13 has a piston 16 which is rotatably linked to rocker 6, for example through a bearing eye 17. Hydraulic cylinder 13 in turn is supported at its back end on the rear edge of carousel 5 by means of a single pivot bearing 18.

(11) Hydraulic cylinder 13 is thus attached to carousel 5 and through its piston 16 to rocker 6 in such a way that piston 16 is able to follow swivel motions of rocker 6 around the latter's axis 9. For example, when rocker 6 swivels downward it extends, and while so doing it pumps hydraulic oil into pressure accumulators 14, 15, which compresses the relevant gas bubbles. The springing reactive force of the gas bubbles reacts on piston 16 and, when the pretensioning of the gas bubbles is appropriately tuned, compensates for the forces and moments acting from outside on rocker 6.

(12) In the case of the present exemplary embodiment, hydraulic cylinder 13 is constructed so that it has a volume of less than 1 liter. Hydraulic cylinder 13 is also designed so that the pressure of hydraulic cylinder 13 is always less than 400 bar, in particular less than 350 bar and preferably less than 300 bar, even at extreme positions of robot arm 2 and at elevated ambient temperatures.

(13) This ensures that all pressurized components of weight equalization system 12, i.e., in particular the two pressure accumulators 14, 15 and hydraulic cylinder 13, always have a volume of less than 1 liter and a maximum pressure of significantly less than 1000 bar.