Cylinder-in-cylinder structure for linear motor machines

Abstract

A tube-in-tube structure (100) for a linear motor machine is disclosed. The tube-in-tube structure includes (a) an outer dimensional frame (20) for responding to maintaining a payload (50) and allowing the payload (50) to move thereon; (b) an inner force frame (10) enclosed within a hollow cavity (22) of the outer dimensional frame (20) and responding to transmitting any reaction force applied by the payload (50) to a bottom of the inner force frame (10), wherein a bottom end of the inner force frame (10) is mounted to a bottom end of the outer dimensional frame (20), and such mounting is positioned to the ground. The inner force frame (10) will directly transmit any reaction force applied by dynamic motion generated by the linear motor machine to the bottom of the inner force frame (10), thereby minimizing or stabilizing vibration caused by linear motor motion.

Description

[0001] Cross-references to related applications

[0002] This application claims the benefit of Singapore Provisional Application No. 10202009051X, filed on September 15, 2020, entitled “A NOVEL TUBE-IN-TUBESTRUCTURE DESIGN FOR LINEAR MOTOR MACHINE”. The teachings of the prior application are hereby incorporated herein by reference. Technical Field

[0003] This invention relates to frame structures, and more particularly to a tube-in-tube structure design for linear motor machines. Background Technology

[0004] Machine tools, semiconductors, and the medical industry all rely heavily on linear motion machines. The performance of these linear machines depends on high speeds and very precise positioning; therefore, the vibrations induced by linear motion machines must be stabilized during operation.

[0005] Generally, a linear motor moving mechanism has (i) measuring elements such as linear bearings and encoder scales, and (ii) force elements such as the motor core mounted on a common base. Newton's third law states that for every action (force) in nature, there is an equal and opposite reaction.

[0006] As the motor moves forward, it exerts an equal reaction force on the common base structure. This reaction force causes the common base structure to vibrate. The base structure will then deflect in the opposite direction to the motor's direction of travel. The motor will have to travel back and forth several times to reach the correct position.

[0007] This means that it takes a long time for a movement to settle into a position. Figure 2 (a) Indicates the conventional structure of the common base structure used as a linear electric motor machine.

[0008] U.S. Patent No. 5,105,109A discloses a support structure for a linear motor drive type for an elevator, the support structure comprising a stator acting as the secondary side of the linear motor and a moving element acting as the primary side of the stator, characterized in that one end of the stator is secured to the building side by a first support device configured to allow vibration of the stator, and the other end of the stator is secured to the building side by a secondary support device that provides a predetermined tension to the stator and absorbs the vibration of the stator.

[0009] U.S. Patent No. 6,098969 A discloses a semi-active variable stiffness control (SAIVS) device that can continuously and smoothly vary its stiffness between a maximum stiffness and a minimum stiffness. It contains four springs and a telescoping tube element arranged in a diamond configuration with a pivot joint at the apex. The SAIVS is mounted as a connection between structural elements and varies the connection stiffness smoothly by changing its configuration in response to a control algorithm in a computer. SUMMARY

[0010] These and other features, aspects, and advantages of the present invention will become better understood with reference to the following drawings, description, and claims.

[0011] It is a primary object of the present invention to provide a tube-in-tube structure (100) for a linear motor machine, said tube-in-tube structure comprising

[0012] (a) an outer metrology frame (20) having a pair of thin length metrology tubes (20') connected with a horizontal cross beam (24), wherein each of said thin length metrology tubes (20') has a top end and a bottom end, said outer metrology frame (20) having a hollow cavity (22) for responding to maintaining a payload (50) and allowing said payload (50) to move thereon;

[0013] (b) an inner force frame (10) having a plurality of inner force tubes (10'), wherein each of said inner force tubes (10') has a top end and a bottom end, and said inner force tubes (10') are connected at their said top ends with an inner horizontal cross beam (24'), said inner force frame (10) being enclosed within said hollow cavity (22) of said outer metrology frame (20) and responding to any reaction force to be exerted by said payload (50) to the bottom of said inner force frame (10);

[0014] wherein said bottom ends of said inner force tubes (10') are mounted to said bottom ends of said outer metrology tubes (20'), and said bottom of said inner force frame (10) is equivalent to said bottom of said outer metrology frame (20), said bottom being equivalent to the location where said outer metrology frame is connected to the ground.

[0015] It is a further object of the present invention to provide a tube-in-tube structure (100) for a linear motor machine, said tube-in-tube structure further comprising a plurality of damping devices (30) disposed between said inner force tubes (10') and said outer metrology tubes (20'), said damping devices (30) being spaced apart between said inner force tubes (10') and said outer metrology tubes (20').

[0016] It is a further object of the present invention to provide a tube-in-tube structure (100) wherein the damping means (30) are located within the hollow cavity (22) of the outer metrology tube (20') in a manner that cancels or reduces the vibrations generated by the linear motor machine in motion.

[0017] It is a further object of the present invention to provide a tube-in-tube structure (100) wherein the vibrations are dynamic movements generated during the operation of the linear motor machine and any reaction forces generated by the linear motor machine are transmitted directly to the bottom of the inner force frame (10) through the inner force tube (10').

[0018] It is a further object of the present invention to provide a tube-in-tube structure (100) wherein the outer metrology tube (20') and the inner force tube (10') are hollow and elongated, made of metal.

[0019] It is a further object of the present invention to provide a tube-in-tube structure (100) for linear motor machines wherein the linear motor movement settling time is significantly reduced because any reaction force directly from the force frame (10) is only a small fraction of that force flowing to the outer metrology frame (20).

[0020] It is a further object of the present invention to provide a tube-in-tube structure (100) for linear motor machines wherein the reaction forces are transmitted directly to the bottom of the tube-in-tube structure through the inner force frame.

[0021] It is a further object of the present invention to provide a tube-in-tube structure (100) for linear motor machines wherein the damping means are used to absorb energy from the vibrations in order to make the movement settle down quickly. BRIEF DESCRIPTION OF DRAWINGS

[0022] A further understanding of the nature and objects of the present invention will become apparent by reference to the ensuing detailed description and drawings, wherein:

[0023] Figure 1 is a perspective view of a tube-in-tube structure for linear motor machines according to the present invention;

[0024] Figure 2 is a cross-sectional view of a conventional tube structure for linear motor machines; and

[0025] Figure 3 is a cross-sectional view of a tube-in-tube structure for linear motor machines according to the present invention. DETAILED DESCRIPTION

[0026] The following detailed description has the most current exemplar}' embodiment of the application performing. The description is not taken in a limiting sense, but is made merely for the purposes of illustrating the general principles of the application as a prelude to the broadest application claimed by the appended claims.

[0027] Reference Figure 1 Generally, a perspective view of a tube-in-tube structure for a linear motion machine according to the present application is shown. The tube-in-tube structure (100), which is a metal structure, is for a linear motor machine in a manufacturing process. The metal structure or tube-in-tube structure (100) comprises (i) an outer structural member denoted as an outer metrology frame (20); (ii) an inner structural member denoted as an inner force frame (10); (iii) a plurality of damping devices (30); and (iv) a base plate (40) that acts as a base for one end of the outer metrology frame (20) and the inner force frame (10). The outer metrology frame (20) has a pair of thin length metrology tubes (20') connected with an outer horizontal beam (24), wherein each of the thin length metrology tubes (20') has a top end and a bottom end, and the inner portion of the outer metrology frame (20) is a hollow cavity (22) and the outer horizontal beam (24) of the outer metrology frame (20) is for responding to maintaining a payload (50) and allowing the payload (50) to move thereon.

[0028] As shown in the figure of the preferred embodiment of the present application, the inner force frame (10) has a pair of inner force tubes (10'), wherein each of the inner force tubes (10') has a top end and a bottom end, and the inner force tubes (10') are connected with an inner horizontal beam (24') at the top end thereof, the inner force tubes (10') are enclosed within the hollow cavity (22) of the outer metrology tubes (20'), and respond to transmitting any reaction force exerted by the payload (50) to the bottom of the inner force tubes (10').

[0029] According to the preferred embodiment of the present application, the plurality of damping devices (30) are disposed between the inner force tubes (10') and the outer metrology tubes (20') within the hollow cavity (22), and the damping devices (30) are generally equally spaced apart between the inner force tubes (10') and the outer metrology tubes (20'). The base plate (40) is a flat base for mounting the bottom end of the inner force tubes (10') and the bottom end of the outer metrology tubes (20'). The inner force frame (10) transmits any reaction force exerted by the dynamic motion generated by the linear motor machine directly to the bottom of the inner force frame (10).

[0030] Generally, linear motor moving mechanisms have a metrology element (such as linear bearing, encoder scale), and a force element (magnetic rail), which are mounted on a common base. Based on Newton's third law of motion, for every action (force) in nature, there is an equal and opposite reaction. As shown in the cross-sectional view of a conventional barrel structure for a linear motion machine Figure 2 when the motor (50) is moving forward, the force exerted by the motor (50) causes an equal and opposite reaction force F on the common base structure. Due to the reaction force, the common base structure will have vibrations. The motor needs to travel back and forth several times in order to be in the right position. Thus, the vibrations need more time to settle down.

[0031] Generally, as shown in Figure 1 a barrel-in-barrel structure (100) for a linear motor 15 machine according to the present invention will exist by utilizing different sized metal hollow beams or metal barrels etc. The smaller sized barrel element which is the inner force frame (10) will be enclosed in the larger sized barrel element which is the outer metrology frame (20). For this structure, the only common contact point is on the base plate (40) where both the bottom ends of the barrel elements (10', 20') are welded or mounted together. The metrology element of the linear motor moving mechanism will be mounted on the outer metrology frame (20), while the force element is mounted on the inner force frame (10).

[0032] Referring to Figure 3 , a cross-sectional view of a barrel-in-barrel structure (100) for a linear motion machine according to the present invention is shown. In this case, Newton's third law of motion applies. In the preferred embodiment of the present invention, the reaction force is directly transmitted through the inner force frame (10) to the base plate (40) of the barrel-in-barrel structure (100). There is vibration that can occur on the inner force frame (10), but the vibration can be significantly reduced from the outer metrology frame (20). Thus, the linear motor motion settling time of the linear motor machine can be significantly reduced because there is no reaction force directly induced on the outer metrology frame (20).

[0033] The barrel-in-barrel structure (100) of the preferred embodiment is novel and unique because the structure (100) of the present invention is compact compared to any prior art conventional structure or similar structure in which another structure or second structure is needed, which thus occupies more space and has a more complex mechanical design and alignment. In the preferred embodiment, the inner force frame (10) is hidden inside the outer metrology frame (20), and the mechanical design is neat, and the alignment needed is much simpler.

[0034] In the present invention, the use of multiple dampening devices (30) improves the dampening of the barrel-in-barrel structure (100), which improves the vibration stability. The dampening devices (30) can be any kind of dampening device such as mechanical dampeners, shock absorbers and any other material or liquid that can be filled between the outer metrology frame (20) and the inner force frame (10). The multiple dampening devices (30) are located within the hollow cavity (22) of the outer metrology frame (20) in a manner that cancels or reduces the vibrations generated by the linear motor machine in motion, or in other words, the dampening devices (30) work to absorb energy from the vibrations to achieve fast motion stability of the structure (100).

[0035] During the operation of the linear motor machine, any reaction force generated by the linear motor machine is directly transmitted through the inner force frame (10) to the bottom of the inner force frame (10). The outer metrology frame (20) and the inner force frame (10) are elongated hollow structures made of metal.

[0036] Because certain changes can be made in the foregoing without departing from the scope of the invention herein involved, it is intended that all matter contained in the above description and shown in the accompanying drawings be interpreted in an illustrative rather than a limiting sense.

Claims

1. A tube-in-tube structure (100) for a linear electric motor machine, the tube-in-tube structure comprising (a) An external measuring frame (20) having a pair of slender measuring cylinders (20') connected to a horizontal beam (24), each of the slender measuring cylinders (20') having a top end and a bottom end, the external measuring frame (20) having a hollow cavity (22) for responding to maintaining a payload (50) and allowing the payload (50) to move thereon; and (b) An internal force frame (10) having a plurality of internal force cylinders (10'), each of which has a top end and a bottom end, and the internal force cylinder (10') being connected at its top end to an inner horizontal beam (24'), the internal force frame (10) being enclosed within the hollow cavity (22) of the outer measuring frame (20) and responding to any reaction force applied by the payload (50) being transmitted to the bottom of the internal force frame (10); wherein the bottom end of the internal force cylinder (10') is mounted to the bottom end of the slender measuring cylinder (20'), and this mounting of the bottom of the internal force frame (10) and the bottom of the outer measuring frame (20) is positioned to the ground; The measuring elements of the linear motor machine will be mounted on the outer measuring frame (20), while the force elements of the linear motor machine will be mounted on the inner force frame (10). The mounting of the bottom of the internal force frame (10) and the bottom of the external measuring frame (20) is positioned to the ground, and any reaction force generated by the linear motor machine is directly transmitted through the internal force frame (10) to the bottom of the internal force frame (10).

2. The cylinder-in-cylinder structure (100) for a linear motor machine as claimed in claim 1, the cylinder-in-cylinder structure further comprising a plurality of damping devices (30), the damping devices being disposed between the inner force cylinder (10') and the slender length weighing cylinder (20'), the damping devices (30) being equidistantly spaced between the inner force cylinder (10') and the slender length weighing cylinder (20').

3. The cylinder-in-cylinder structure (100) for a linear motor machine as claimed in claim 1, wherein the internal force cylinder (10') is a small-sized cylinder element surrounding the slender weighing cylinder (20'), and the slender weighing cylinder (20') is a large-sized cylinder element.

4. The cylinder-in-cylinder structure (100) for a linear motor machine as claimed in claim 2, wherein the internal force cylinder (10') is concealed within the slender weighing cylinder (20').

5. The cylinder-in-cylinder structure (100) for a linear motor machine as claimed in claim 4, further comprising a base plate (40) that serves as a base for one end of the outer measuring frame (20) and the inner force frame (10), the common contact point of the base plate (40) being formed by welding or assembling the bottom ends of the inner force cylinder (10') and the slender measuring cylinder (20').

6. The tube-in-tube structure (100) for a linear electric motor machine as claimed in claim 2, wherein the damping device (30) is located within the hollow cavity (22) of the outer measuring frame (20) in a manner that dissipates the vibrational energy generated by the moving linear electric motor machine.

7. The tube-in-tube structure (100) for a linear electric motor machine as claimed in claim 2 or claim 6, wherein the damping device (30) comprises a viscous liquid, a particulate medium, and a viscoelastic material.

8. The tube-in-tube structure (100) for a linear electric motor machine as claimed in claim 1, wherein the outer measuring frame (20) and the inner force frame (10) are hollow beams made of metal.

9. The tube-in-tube structure (100) for a linear electric motor machine as claimed in claim 1, wherein the outer measuring frame (20) is used to provide geometric guidance for the movement of the linear electric motor machine.

10. The tube-in-tube structure (100) for a linear electric motor machine as claimed in claim 2 or claim 6, wherein the plurality of damping devices (30) are operatively arranged such that energy caused by vibrations of the linear electric motor machine is absorbed to achieve rapid and stable motion.

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