Packaged Piezoelectric Stack Actuator with Adjustable Preload

Abstract

The present invention belongs to the field of precision driving and positioning, and specifically relates to a packaged piezoelectric stack driver with adjustable preload, including a metal shell, a transmission rod, a stacked piezoelectric ceramic, a shell base and a voice coil motor, wherein the metal shell is a hollow columnar structure, the shell base is fixed to the bottom end of the metal shell, the stacked piezoelectric ceramic is located in the metal shell, and the bottom end of the stacked piezoelectric ceramic is fixed to the shell base through the piezoelectric ceramic base, the top end of the stacked piezoelectric ceramic abuts the bottom end of the transmission rod, the top end of the transmission rod extends out of the metal shell, the voice coil motor is located in the metal shell, and a preload is applied to the stacked piezoelectric ceramic after power is turned on. The present invention uses a voice coil motor to make the preload of the stacked piezoelectric ceramic an adjustable physical quantity, which will not weaken the magnitude of the force when an output force is required, thereby improving the load driving capacity of the stacked piezoelectric driver; when a return is required, the stacked piezoelectric ceramic can be controlled to return at different speeds to adapt to different frequency response occasions.

Description

Technical Field

[0001] The invention belongs to the technical field of precision driving and positioning, and in particular relates to a packaged piezoelectric stack driver with adjustable preload force. Background Art

[0002] Packaged piezoelectric stack actuators usually use a cylindrical housing to protect the stacked piezoelectric ceramics and provide internal mechanical preload, which can provide nanometer resolution, hundreds of micrometers of travel, and microsecond response time. Due to the very compact housing of the packaged piezoelectric stack actuator, it has the characteristics of modularity, small size, and high resonance rate, making it very suitable for precision driving and positioning fields, such as machine tools, active vibration isolation, laser tuning, beam control, or microlithography.

[0003] Stacked piezoelectric ceramics are the core components of packaged piezoelectric stack drivers. Due to the inverse piezoelectric effect, stacked piezoelectric ceramics respond quickly and deform when a control voltage is applied, thereby generating an output force and ultimately outputting a displacement drive load. However, when the control voltage is reduced, the stacked piezoelectric ceramics return to the expected deformation very slowly, so it is necessary to provide a preload to speed up the return process of the stacked piezoelectric ceramics and improve their dynamic response performance.

[0004] In packaged piezoelectric stack drivers, elastic structures such as disc springs are usually used to provide mechanical preload. The size of the preload is related to the elastic coefficient of the elastic structure and the deformation of the stacked piezoelectric ceramics, and it always exists during the operation of the packaged piezoelectric stack driver. Undoubtedly, in order to enable the stacked piezoelectric ceramics to have better dynamic response performance, part of the output force generated by the stacked piezoelectric ceramics is offset by the preload, which weakens the driving load capacity. On the other hand, since the elastic coefficient of the elastic structure is basically determined after the processing is completed, the preload size of the packaged piezoelectric stack driver cannot be adjusted, and it cannot be widely adapted to different dynamic characteristics and load requirements. Summary of the invention

[0005] In view of the above technical problems, the present invention aims to provide a packaged piezoelectric stack driver with adjustable preload force. To solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A packaged piezoelectric stack driver with adjustable preload force comprises a metal shell, a transmission rod, a stacked piezoelectric ceramic, a shell base and a voice coil motor. The metal shell is a hollow columnar structure. The shell base is fixed to the bottom end of the metal shell. The stacked piezoelectric ceramic is located inside the metal shell, and the bottom end of the stacked piezoelectric ceramic is fixed to the shell base via the piezoelectric ceramic base. The top end of the stacked piezoelectric ceramic abuts against the bottom end of the transmission rod, and the top end of the transmission rod extends out of the metal shell. The voice coil motor is located inside the metal shell. After power is turned on, a preload force is applied to the stacked piezoelectric ceramic.

[0007] Furthermore, a circular through hole is formed at the top of the metal shell.

[0008] Furthermore, the transmission rod is composed of an integrally formed push rod and a platform edge, the top end of the push rod passes through the circular through hole and extends out of the metal shell, and the platform edge abuts against the top end of the stacked piezoelectric ceramics.

[0009] Furthermore, the voice coil motor is a dynamic voice coil motor or a moving magnet voice coil motor; wherein the dynamic voice coil motor includes a coil winding and a permanent magnet, the coil winding is sleeved on the top rod and abuts against the edge of the table, and the permanent magnet is fixed in the metal shell by a permanent magnet shell; the moving magnet voice coil motor includes a coil winding and a magnet, the magnet is sleeved on the top rod and abuts against the edge of the table, and the coil winding is fixed in the metal shell by a coil winding shell.

[0010] Furthermore, the magnet is a permanent magnet or a magnetic conductor.

[0011] Furthermore, the outer diameter of the permanent magnet housing or the coil winding housing is equal to the inner diameter of the metal housing.

[0012] Furthermore, the diameter of the circular through hole is larger than the diameter of the top rod and smaller than the diameter of the platform edge.

[0013] Furthermore, the preload force applied to the stacked piezoelectric ceramics is adjusted by controlling the magnitude of the current applied to the coil winding.

[0014] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0015] A voice coil motor is formed by using coil windings and permanent magnets, so that the preload force applied to the stacked piezoelectric ceramics becomes an adjustable physical quantity. When the packaged piezoelectric stack driver is required to generate a large output force to drive a large load, the control current applied to the coil windings is stopped, and the preload force applied to the stacked piezoelectric ceramics is canceled, so that the output force generated by the stacked piezoelectric ceramics can be transmitted to the load without being weakened, thereby improving the load driving capability of the packaged piezoelectric stack driver; when the packaged piezoelectric stack driver is required to return quickly, current is applied to the coil windings, and preload force is applied to the stacked piezoelectric ceramics, forcing the stacked piezoelectric ceramics to return quickly to the expected position; in addition, by controlling the magnitude of the current applied to the coil windings, the magnitude of the preload force is controlled, and the response speed of the stacked piezoelectric ceramics to input signals of different frequencies is adjusted, thereby improving the dynamic response capability of the packaged piezoelectric stack driver. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic cross-sectional structural diagram of an assembled packaged piezoelectric stack driver with adjustable preload force according to Embodiment 1 of the present invention;

[0017] Figure 2is a schematic diagram of an exploded structure of a packaged piezoelectric stack driver with adjustable preload force provided according to Embodiment 1 of the present invention;

[0018] Figure 3 is a schematic diagram of the cross-sectional structure of a metal housing provided according to Embodiment 1 of the present invention;

[0019] Figure 4 is a schematic cross-sectional structure diagram of a transmission rod provided according to Embodiment 1 of the present invention;

[0020] Figures 5 to 7 Schematic diagram of adjusting the preload force of the packaged piezoelectric stack driver provided in Example 1 of the present invention.

[0021] The reference numerals include: metal shell 100, inner cavity 101, circular through hole 102, coil winding shell 103, coil winding 104, transmission rod 200, platform edge 201, top rod 202, magnet 203, stacked piezoelectric ceramics 300, piezoelectric ceramic base 400, shell base 500. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solution and advantages of the invention more clear, the invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described here are only used to explain the invention and do not constitute a limitation of the invention.

[0023] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0024] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0025] In the description of the invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installation", "connection" and "connection" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the invention can be understood according to specific circumstances.

[0026] The present invention will be described in detail below with reference to the accompanying drawings and in combination with embodiments.

[0027] An embodiment of the present invention provides a packaged piezoelectric stack driver with adjustable preload force, including a metal shell, a transmission rod, a stacked piezoelectric ceramic, a shell base and a voice coil motor. The metal shell is a hollow columnar structure, the shell base is fixed to the bottom end of the metal shell, the stacked piezoelectric ceramic is located in the metal shell, and the bottom end of the stacked piezoelectric ceramic is fixed to the shell base through the piezoelectric ceramic base, the top end of the stacked piezoelectric ceramic is abutted against the bottom end of the transmission rod, the top end of the transmission rod extends out of the metal shell, the voice coil motor is located in the metal shell, and a preload force is applied to the stacked piezoelectric ceramic after power is turned on.

[0028] The present invention controls the presence and magnitude of preload by determining whether current is applied to the voice coil motor and the magnitude of the applied current. Specifically, when the stacked piezoelectric ceramics need to output displacement, a control voltage is applied to the stacked piezoelectric ceramics, and the application of current to the voice coil motor is stopped. At this time, there is no preload, and the output force of the stacked piezoelectric ceramics is directly transmitted to the load without being weakened. When the stacked piezoelectric ceramics need to be quickly retracted and returned to their original positions, current is applied to the voice coil motor, and preload is applied to the stacked piezoelectric ceramics, forcing the stacked piezoelectric ceramics to quickly return to their expected positions. In addition, by controlling the magnitude of the current applied to the voice coil motor, the magnitude of the preload can be controlled, thereby controlling the return speed of the stacked piezoelectric ceramics.

[0029] The present invention makes the preload force applied to the stacked piezoelectric ceramics an adjustable physical quantity through the setting of the voice coil motor. When the stacked piezoelectric ceramics need a larger output force, the force will not be weakened, thereby improving the load driving capacity of the packaged piezoelectric stack driver; when the stacked piezoelectric ceramics need to return, the stacked piezoelectric ceramics can be controlled to return at different speeds to adapt to different frequency response occasions.

[0030] The voice coil motor includes a coil winding and a permanent magnet. According to the different arrangements of the coil winding and the permanent magnet, the voice coil motor can be divided into a moving magnet voice coil motor and a dynamic coil voice coil motor. The following two specific embodiments are used to illustrate the packaged piezoelectric stack driver using the two voice coil motors.

[0031] Example 1

[0032] like Figure 1-Figure 4 As shown, the encapsulated piezoelectric stack driver with adjustable preload provided in Example 1 of the present invention includes a metal shell 100, a transmission rod 200, a stacked piezoelectric ceramic 300, a piezoelectric ceramic base 400 and a shell base 500. The metal shell 100 is a hollow columnar structure, and the hollow part forms an inner cavity 101. The bottom end of the metal shell 100 is not closed and the shell base 500 is fixed. The shell base 500 serves as the base of the metal shell 100 and plays the role of encapsulating the metal shell 100. The top of the metal shell 100 is closed and a circular through hole 102 is opened. A coil winding shell 103 is arranged in the metal shell 100. The outer diameter of the coil winding shell 103 is the same as the inner diameter of the metal shell 100. The coil winding 104 is installed in the coil winding shell 103, and the coil winding 104 is fixed in the metal shell 100 and remains stationary. Through holes are formed at the upper and lower ends of the coil winding shell 103 for the transmission rod 200 to pass through.

[0033] The transmission rod 200 is a columnar structure, which is composed of an integrally formed edge 201 and a top rod 202. The diameter of the circular through hole 102 is smaller than the diameter of the edge 201 and larger than the diameter of the top rod 202. The top rod 202 passes upward through the circular through hole 102 and then extends out of the metal shell 100 to contact the load. The edge 201 contacts the top of the stacked piezoelectric ceramic 300, and the bottom end of the stacked piezoelectric ceramic 300 is fixed to the shell base 500 through the piezoelectric ceramic base 400.

[0034] The displacement output by the stacked piezoelectric ceramic 300 acts on the load through the transmission rod 200, thereby realizing the driving of the load by the packaged piezoelectric stack driver.

[0035] A magnet 203 is mounted on the top rod 202. The magnet 203 may be a permanent magnet or a conductive magnet. The magnet 203 abuts against the platform edge 201. The platform edge 201 limits the magnet 203. The outer diameter of the magnet 203 is slightly smaller than the diameter of the platform edge 201. The magnet 203 moves with the transmission rod 200.

[0036] The magnet 203 mounted on the transmission rod 200 and moving with the transmission rod 200 and the coil winding 104 fixed in the coil winding housing 103 form a moving magnet type voice coil motor. Whether an electromagnetic field is generated and whether the magnet 203 is subjected to electromagnetic force is determined by whether a control current is applied to the coil winding 104, that is, whether the stacked piezoelectric ceramic 300 is subjected to preload. By controlling the direction of the current applied to the coil winding 104, the magnet 203 can be subjected to an electromagnetic force opposite to the driving force of the stacked piezoelectric ceramic 300, thereby applying a preload to the stacked piezoelectric ceramic 300; by controlling the magnitude of the current applied to the coil winding 104, the magnet 203 can be subjected to electromagnetic forces of different magnitudes, thereby causing the stacked piezoelectric ceramic 300 to be subjected to preloads of different magnitudes, thereby accelerating or slowing down the speed at which the stacked piezoelectric ceramic 300 recovers its own deformation.

[0037] More specifically, the packaged piezoelectric stack driver is used as follows:

[0038] like Figure 5 As shown, when a control voltage is applied to the stacked piezoelectric ceramic 300, an upward driving force is generated on the transmission rod 200, and the transmission rod 200 moves upward. At this time, there is no need to apply current to the coil winding 104, and no pre-tightening force is generated, so the driving force can be directly transmitted to the load through the transmission rod 200 without being weakened, thereby improving the load-carrying capacity of the packaged piezoelectric stack driver.

[0039] like Figure 6 and Figure 7 As shown, when the control voltage of the stacked piezoelectric ceramic 300 is reduced, a pre-tightening force needs to be applied to make it fall back to the desired position quickly. At this time, a control current is applied to the coil winding 104 to generate a magnetic field with a polarity opposite to that of the magnet 203, thereby generating an electromagnetic force that pushes the magnet 203 to move downward, driving the transmission rod 200 to move downward until it is balanced with the output force of the stacked piezoelectric ceramic 300. In addition, if the control current flowing through the coil winding 104 is increased, the electromagnetic force that pushes the magnet 203 to move downward will become larger, thereby increasing the return speed of the stacked piezoelectric ceramic 300 and improving the dynamic response capability of the packaged piezoelectric stack driver.

[0040] Example 2

[0041] The difference between Example 2 and Example 1 is that a dynamic voice coil motor is used. The dynamic voice coil motor includes a coil winding and a permanent magnet. The coil winding is mounted on a top rod and abuts against the edge of the table. The coil winding moves with the top rod. The permanent magnet is installed in a permanent magnet housing and fixed in a metal housing to remain stationary.

[0042] Whether the coil winding is magnetic or not can be determined by whether the control current is applied to the coil winding, that is, whether the stacked piezoelectric ceramics are subjected to preload. By controlling the direction of the current applied to the coil winding, the magnetic coil winding can be subjected to an electromagnetic force in the opposite direction to the driving force of the stacked piezoelectric ceramics in the magnetic field generated by the permanent magnet, thereby applying a preload to the stacked piezoelectric ceramics; by controlling the magnitude of the current applied to the coil winding, the coil winding can be subjected to electromagnetic forces of different magnitudes, thereby compressing the stacked piezoelectric ceramics to subject them to preloads of different magnitudes, and speeding up or slowing down the speed at which the stacked piezoelectric ceramics recover their own deformation.

[0043] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. Those skilled in the art may change, modify, replace and modify the above embodiments within the scope of the present invention.

[0044] The above specific implementations of the present invention do not constitute a limitation on the protection scope of the present invention. Any other corresponding changes and modifications made based on the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A packaged piezoelectric stack driver with adjustable preload force, characterized in that: It includes a metal shell, a transmission rod, a stacked piezoelectric ceramic, a shell base and a voice coil motor. The metal shell is a hollow columnar structure. The shell base is fixed to the bottom end of the metal shell. The stacked piezoelectric ceramic is located in the metal shell, and the bottom end of the stacked piezoelectric ceramic is fixed to the shell base through the piezoelectric ceramic base. The top end of the stacked piezoelectric ceramic abuts against the bottom end of the transmission rod, and the top end of the transmission rod extends out of the metal shell. The voice coil motor is located in the metal shell, and a pre-tightening force is applied to the stacked piezoelectric ceramic after power is turned on.

2. The packaged piezoelectric stack driver with adjustable preload force according to claim 1, characterized in that: A circular through hole is formed on the top of the metal shell.

3. The packaged piezoelectric stack driver with adjustable preload force according to claim 2, characterized in that: The transmission rod is composed of an integrally formed top rod and a platform edge. The top end of the top rod passes through a circular through hole and extends out of a metal shell, and the platform edge abuts against the top end of the stacked piezoelectric ceramics.

4. The packaged piezoelectric stack driver with adjustable preload force according to claim 3, characterized in that: The voice coil motor is a moving coil type voice coil motor or a moving magnet type voice coil motor; wherein, The moving coil type voice coil motor comprises a coil winding and a permanent magnet, wherein the coil winding is sleeved on the top rod and abuts against the edge of the table, and the permanent magnet is fixed in the metal shell through the permanent magnet shell; The moving magnet voice coil motor comprises a coil winding and a magnet. The magnet is sleeved on a top rod and abuts against a table edge. The coil winding is fixed in a metal shell through a coil winding shell.

5. The packaged piezoelectric stack driver with adjustable preload force according to claim 4, characterized in that: The magnet is a permanent magnet or a conductive magnet.

6. The packaged piezoelectric stack driver with adjustable preload force according to claim 4, characterized in that: The outer diameter of the permanent magnet housing or the coil winding housing is equal to the inner diameter of the metal housing.

7. The packaged piezoelectric stack driver with adjustable preload force according to claim 3, characterized in that: The diameter of the circular through hole is larger than the diameter of the top rod and smaller than the diameter of the platform edge.

8. The packaged piezoelectric stack driver with adjustable preload force according to claim 4, characterized in that: The preload force applied to the stacked piezoelectric ceramics is adjusted by controlling the current applied to the coil winding.

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