Stroke detection device for a piezoelectric actuator

Abstract

The present application belongs to the technical field of driving element stroke detection, and particularly relates to a stroke detection device of a piezoelectric driver, which comprises: a grating support, which is movably connected with the shell of the piezoelectric driver along a first direction; the grating support is movably connected with the mover of the piezoelectric driver through a flexible hinge, and the flexible hinge is configured to be capable of transmitting the movement of the mover along the first direction to the grating support; a grating strip, which is installed on the grating support, and the length direction of the grating strip is parallel to the first direction; and a reading head, which is fixedly arranged in the shell of the piezoelectric driver, and the reading head is oppositely arranged with the grating strip. By introducing the flexible hinge, on the one hand, the high precision and high reliability of the stroke detection system can be ensured; on the other hand, the sticking and stick-slip phenomenon between the mover and the guide rail caused by the complete rigid constraint of the mover can be avoided.

Description

Technical Field

[0001] This invention belongs to the field of drive element stroke detection technology, specifically relating to a stroke detection device for a piezoelectric actuator. Background Technology

[0002] Piezoelectric actuators typically use a linear encoder and a reading head for stroke detection. To ensure the accuracy of the reading, a fixed distance must be maintained between the linear encoder and the reading head. The linear encoder in a piezoelectric actuator is generally fixed relative to the mover. To ensure the straightness of the linear encoder's trajectory, the mover's movement must be strictly limited to a straight path. However, in some special types of piezoelectric actuators, such as inchworm motors, the piezoelectric elements apply thrust to the mover from both sides. In practical applications, it is difficult to ensure that the forces exerted by the piezoelectric elements on the mover on both sides are completely synchronized and consistent. This difference in force can cause lateral torque in the mover. When the mover's trajectory is strictly limited, this lateral torque can cause lateral stress between the mover and the trajectory guiding components, leading to mover jamming. Therefore, there is an urgent need for a stroke detection device that can improve the smoothness of the mover's movement while ensuring stroke detection accuracy. Summary of the Invention

[0003] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide a stroke detection device that can improve the smoothness of the mover movement while ensuring the accuracy of stroke detection.

[0004] To achieve the above and other related objectives, the present invention provides a travel detection device for a piezoelectric actuator, comprising:

[0005] A grating support is movably connected to the housing of a piezoelectric actuator along a first direction; the grating support is movably connected to the mover of the piezoelectric actuator via a flexible hinge, the flexible hinge being configured to transmit the motion of the mover along the first direction to the grating support, the first direction being the motion direction of the power output end of the piezoelectric actuator driven by the mover;

[0006] A grating strip is mounted on the grating bracket, and the length direction of the grating strip is parallel to the first direction;

[0007] The reading head is fixedly installed inside the housing of the piezoelectric actuator, and the reading head is arranged opposite to the grating strip.

[0008] In an optional embodiment of the present invention, the flexible hinge includes two rigid roots and an elastic deformation portion connected between the two roots. The length of the elastic deformation portion in the first direction is much greater than its thickness in the second direction, which is perpendicular to the first direction. The two roots are respectively disposed on the grating support and the mover, so that the grating support and the mover are interconnected in a third direction via the flexible hinge, which is perpendicular to the first direction and the second direction, respectively.

[0009] In an optional embodiment of the present invention, the grating support includes a rectangular frame, which is sleeved on the outside of the mover along the second direction. The mover includes a first side and a second side that are parallel to and opposite to each other in the first direction. The rectangular frame includes a first arm opposite to the first side and a second arm opposite to the second side. At least two flexible hinges are provided, at least one of which is disposed between the first arm and the first side, and at least one other flexible hinge is disposed between the second arm and the second side.

[0010] In an optional embodiment of the present invention, the flexible hinge is integrally formed with the moving part, and the flexible hinge is detachably connected to the grating support.

[0011] In an optional embodiment of the present invention, the flexible hinge is used to connect one root of the grating bracket as a first root; the grating bracket is provided with a mounting groove extending along the third direction, the mounting groove extending along the second direction to one side surface of the grating bracket to form a slot, the mounting groove is provided with protrusions on the two opposite side walls along the first direction, the first root is provided with lugs at both ends in the first direction, the first root is accommodated in the mounting groove, the lugs are located on the side of the protrusion away from the mover, the lugs are provided with a threaded hole extending along the third direction, the threaded hole is provided with a set screw, and the set screw abuts against the side of the protrusion away from the mover.

[0012] In an optional embodiment of the present invention, the groove opening of the mounting groove is provided with a pressure block, which is detachably fixedly connected to the grating bracket to close the groove opening and press the first root along the second direction.

[0013] In an optional embodiment of the present invention, the grating support is provided with a guide portion, a linear bearing arranged along the first direction is provided between the guide portion and the housing of the piezoelectric actuator, and an anti-rotation portion is provided between the guide portion and the housing of the piezoelectric actuator to prevent the guide portion from rotating about an axis parallel to the first direction.

[0014] In an optional embodiment of the present invention, the guide portion is formed by the power output terminal of the piezoelectric actuator.

[0015] In an optional embodiment of the present invention, the grating support is provided with a positioning surface parallel to the first direction, and one of the long sides of the grating strip is in contact with the positioning surface.

[0016] In an optional embodiment of the present invention, two flexible hinges are provided, and the two flexible hinges are respectively connected to the two opposite ends of the mover along the first direction. The grating support includes a first part and a second part located at the two ends of the mover along the first direction, respectively. One flexible hinge is connected to the first part, and the other flexible hinge is connected to the second part.

[0017] The technical advantages of this invention are as follows: By introducing a flexible hinge, this invention achieves the coordination and decoupling of the motion degree of freedom of the mover and the constraint requirements of the grating measurement system. Specifically, the flexible hinge, as a precise motion conversion interface, plays a core role in two aspects: Firstly, it has high rigidity in the first direction, enabling it to transmit the reciprocating translational motion of the mover body to the grating support almost without loss or lag, thereby driving the grating strip to move stably along a preset precise straight trajectory. This fundamentally ensures that a constant optimal gap is maintained between the grating strip and the fixed reading head, eliminating reading errors caused by gap fluctuations and guaranteeing the stability of the stroke detection system. High precision and high reliability; on the other hand, the flexible hinge has appropriate flexibility in the plane perpendicular to the driving direction, allowing the mover to make slight adaptive deflection and displacement when subjected to unbalanced torque generated by the non-completely synchronous driving of the piezoelectric devices on both sides. This releases and effectively absorbs these harmful lateral torques and stresses on the spot, without transmitting them to the grating strip and its guiding system. This allows the system to successfully avoid the jamming and stick-slip phenomenon between the mover and the guide rail caused by the completely rigid constraint without sacrificing measurement accuracy. Ultimately, it achieves the dual purpose of high-precision stroke detection and long-term stable and smooth operation of the mover. Attached Figure Description

[0018] Figure 1 This is a cross-sectional view of a piezoelectric actuator using the stroke detection device of the present invention;

[0019] Figure 2 yes Figure 1 AA section view;

[0020] Figure 3 yes Figure 2 A magnified view of part of the I;

[0021] Figure 4 yes Figure 2 BB cross-sectional view;

[0022] Figure 5 yes Figure 4 Partial magnified view of section II;

[0023] Figure 6 This is a schematic diagram of the assembly structure of the grating bracket provided in the first embodiment of the present invention;

[0024] Figure 7 This is an exploded view of the assembly structure of the grating support provided in the first embodiment of the present invention;

[0025] Figure 8 This is a schematic diagram of the assembly structure of the grating bracket provided in the second embodiment of the present invention;

[0026] Explanation of reference numerals in the attached drawings: 10, housing; 20, mover; 30, piezoelectric device; 40, power output end; 50, linear bearing; 60, grating bracket; 61, mounting groove; 62, protrusion; 63, pressure block; 64, positioning surface; 70, flexible hinge; 71, first root; 711, lug; 712, set screw; 72, second root; 73, elastic deformation part; 80, grating strip; 90, reading head. Detailed Implementation

[0027] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that, unless otherwise specified, the following embodiments and features described therein can be combined with each other.

[0028] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the illustrations only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0029] The transmission principle of the inchworm motor is as follows: Figure 1As shown, its power output end 40 reciprocates relative to the housing 10 along the first direction X. The power output end 40 is connected to the mover 20. Piezoelectric devices 30 are provided on both sides of the mover 20. The piezoelectric devices 30 on both sides can generate extension and oscillation under the action of piezoelectric effect. The piezoelectric devices 30 on both sides can drive the mover 20 to move along the first direction X by synchronously sweeping and oscillating. In this dual-sided piezoelectric drive device, the dynamic characteristics of the piezoelectric devices 30 on both sides (such as displacement-voltage hysteresis, creep, and inconsistent dynamic response) make it difficult to achieve complete synchronization. This results in amplitude and phase differences in the driving force acting on the mover 20, creating a deflection torque around the center of mass of the mover 20. When a high-rigidity linear guide mechanism is used to strictly constrain the degrees of freedom of the mover 20, this torque cannot be released through the slight deflection of the mover 20, and is thus converted into lateral contact stress between the mover 20 and the guide mechanism contact surface. This lateral stress not only significantly increases the static frictional resistance of the guide surface, but also induces a stick-slip effect in reciprocating motion, causing the mover 20 to jam or become unstable. Some solutions, when detecting the stroke of the piezoelectric actuator, have to strictly constrain the mover 20 to a straight trajectory in order to ensure that the relative distance between the grating strip and the reading head is consistent, making it impossible to balance the accuracy of stroke detection and the smoothness of the mover 20's movement. To address this, the present invention provides a stroke detection device for a piezoelectric actuator. This stroke detection device utilizes a flexible hinge 70 to decouple the motion of the mover 20 and the grating strip 80, allowing the mover 20 to transmit motion in the first direction X only to the grating strip 80. The grating strip 80 is strictly constrained on a straight trajectory, ensuring that the distance between the grating strip 80 and the reading head 90 remains consistent, thereby improving detection accuracy. Simultaneously, it allows the mover 20 to deflect slightly in other directions, thereby releasing the deflection torque generated by the piezoelectric device 30 on the mover 20, preventing the mover 20 from jamming, and ensuring the smoothness of the mover 20's movement.

[0030] The technical solution of the present invention will be described in detail below with reference to specific embodiments:

[0031] Please see Figures 1 to 8 As shown, an embodiment of the present invention provides a stroke detection device for a piezoelectric actuator. The stroke detection device includes a grating support 60, a grating strip 80, and a reading head 90. The grating support 60 is movably connected to the housing 10 of the piezoelectric actuator along a first direction X. The grating support 60 is movably connected to the mover 20 of the piezoelectric actuator via a flexible hinge 70, which is configured to transmit the movement of the mover 20 along the first direction X to the grating support 60. The first direction X is the direction of movement of the power output end 40 of the piezoelectric actuator driven by the mover 20. The grating strip 80 is mounted on the grating support 60, and the length direction of the grating strip 80 is parallel to the first direction X. The reading head 90 is fixedly disposed inside the housing 10 of the piezoelectric actuator, and the reading head 90 is disposed opposite to the grating strip 80.

[0032] This invention achieves coordination and decoupling between the motion degrees of freedom of the mover 20 and the constraints of the grating measurement system by introducing a flexible hinge 70. Specifically, the flexible hinge 70, as a precise motion conversion interface, plays a core role in two aspects: Firstly, it has high rigidity in the first direction X, enabling it to transmit the reciprocating translational motion of the main body of the mover 20 to the grating support 60 with almost no loss and no lag, thereby driving the grating strip 80 to move stably along a preset precise linear trajectory. This fundamentally ensures that a constant optimal gap is maintained between the grating strip 80 and the fixed reading head 90, eliminating reading errors caused by gap fluctuations and guaranteeing the high precision of the stroke detection system. On the one hand, it offers high reliability; on the other hand, the flexible hinge 70 has appropriate flexibility in the plane perpendicular to the driving direction, allowing the mover 20 to make slight adaptive deflections and displacements when subjected to unbalanced torques generated by the non-completely synchronous driving of the piezoelectric devices 30 on both sides. This releases and effectively absorbs these harmful lateral torques and stresses on-site, without transmitting them to the grating strip 80 and its guiding system. This allows the system to successfully avoid the jamming and sticking phenomena between the mover 20 and the guide rail caused by being completely rigidly constrained, without sacrificing measurement accuracy. Ultimately, it achieves the dual purpose of high-precision stroke detection and long-term stable and smooth operation of the mover 20.

[0033] Please see Figure 3 , Figure 5 , Figure 7As shown, in an optional embodiment of the present invention, the flexible hinge 70 includes two rigid roots (i.e., a first root 71 and a second root 72) and an elastic deformation portion 73 connected between the two roots. The length of the elastic deformation portion 73 in the first direction X is much greater than its thickness in the second direction Y, which is perpendicular to the first direction X. The two roots are respectively disposed on the grating support 60 and the mover 20, so that the grating support 60 and the mover 20 are connected to each other in a third direction Z by the flexible hinge 70, which is perpendicular to the first direction X and the second direction Y, respectively. This invention constructs a direction-selective motion coupling mechanism by specifically designing the elastic deformation portion 73 of the flexible hinge 70 as a flat structure with a thickness much greater in the first direction X than in the second direction Y. This specific geometry gives it high rigidity in the first direction X, effectively transmitting the main driving force of the mover 20 to the grating support 60 and ensuring that the grating strip 80 accurately follows the effective stroke of the mover 20. However, in the second direction Y and the third direction Z, which are perpendicular to it, this flat structure is prone to bending deformation, thereby accommodating possible lateral movements of the mover 20. The deflection provides a flexible degree of freedom; this structure realizes a directional hard connection and multi-dimensional soft decoupling between the mover 20 and the grating support 60, and the first direction X linear motion necessary for power output is accurately transmitted, ensuring detection accuracy; while the harmful lateral force and deflection torque caused by asynchronous driving force are effectively absorbed and released by the elastic deformation part 73 through its own micro-deformation, avoiding the transmission of these interference forces to the grating strip 80, which would cause it to move undesirably or collide with the reading head 90. At the same time, it also fundamentally removes the rigid constraint on the mover 20, greatly improving its smoothness of movement.

[0034] Please see Figure 2 , Figure 4 , Figure 6 , Figure 7As shown, in an optional embodiment of the present invention, the grating support 60 includes a rectangular frame, which is sleeved on the outside of the mover 20 along the second direction Y. The mover 20 includes a first side and a second side that are parallel to and opposite to the first direction X. The rectangular frame includes a first arm opposite to the first side and a second arm opposite to the second side. At least two flexible hinges 70 are provided, at least one of which is disposed between the first arm and the first side, and at least one other flexible hinge 70 is disposed between the second arm and the second side. This invention constructs a balanced force transmission system by employing a symmetrical layout of a rectangular frame fitted around the outside of the mover 20 and symmetrically setting flexible hinges 70 on two opposite sides of the mover 20. This symmetrical structure ensures that the driving force of the mover 20 in the first direction X can be synchronously and evenly transmitted to the grating support 60 through the flexible hinges 70 on both sides, effectively avoiding the off-center load or torsional deformation of the grating strip 80 that may be caused by unilateral driving, thereby further ensuring the straightness of the motion trajectory of the grating strip 80 and the stability of the reading. At the same time, this double-sided constraint design allows the mover 20 to deflect slightly to release lateral torque while providing it with better radial support, enhancing the motion stability of the system in the non-driving direction.

[0035] Please see Figure 7 As shown, in an optional embodiment of the present invention, the flexible hinge 70 and the mover 20 are integrally formed, and the flexible hinge 70 is detachably connected to the grating support 60. By designing the flexible hinge 70 and the mover 20 as an integral unit, the present invention significantly simplifies the number of parts and assembly steps, not only reducing manufacturing costs but also fundamentally ensuring the precision and structural strength of the connection between the hinge and the mover 20, thus ensuring the reliability of power transmission. Simultaneously, the detachable connection between the flexible hinge 70 and the grating support 60 allows for easy separation of the entire detection module from the mover 20 when vulnerable or calibrated components such as the grating strip 80 or the reading head 90 need replacement or maintenance, without damaging the core drive structure, greatly improving the maintainability of the equipment.

[0036] Please see Figure 3 , Figure 5 , Figure 7As shown, in an optional embodiment of the present invention, the flexible hinge 70 is used to connect a root of the grating bracket 60 as a first root 71; the grating bracket 60 is provided with a mounting groove 61 extending along the third direction Z, the mounting groove 61 extending along the second direction Y to one side surface of the grating bracket 60 to form a slot, the mounting groove 61 has protrusions 62 on the two opposite side walls along the first direction X, the first root 71 has lugs 711 at both ends in the first direction X, the first root 71 is accommodated in the mounting groove 61, the lugs 711 are located on the side of the protrusion 62 away from the mover 20, the lugs 711 are provided with a threaded hole extending along the third direction Z, the threaded hole is provided with a set screw 712, the set screw 712 abuts against the side of the protrusion 62 away from the mover 20. This invention achieves efficient radial self-centering and precise axial positioning by cooperating with the mounting groove 61, the protrusion 62, and the first root 71 with the lug 711. After the first root 71 is placed into the mounting groove 61, the protrusion 62 can be tightened by screwing in the set screw 712, thereby correcting the mover 20 to the design center position of the grating support 60 in the third direction Z. This process effectively compensates for the cumulative errors in the machining and assembly of parts, ensuring that a uniform initial gap is formed between the two sides of the mover 20 and the arm of the grating support 60, providing the necessary conditions for the smooth deflection of the mover 20.

[0037] Please see Figure 5 , Figure 6 , Figure 7 As shown, in an optional embodiment of the present invention, the groove opening of the mounting groove 61 is provided with a pressure block 63. The pressure block 63 is detachably fixedly connected to the grating bracket 60 to close the groove opening and press the first root 71 along the second direction Y. The present invention constructs a connection structure that combines convenient adjustment and reliable locking by adding a detachable pressure block 63 to close the groove opening of the mounting groove 61. During the assembly and debugging stage, the pressure block 63 can be loosened to adjust the set screw 712, which facilitates precise adjustment of the position of the first root 71 to achieve automatic alignment between the mover 20 and the grating bracket 60 and ensures uniform initial gap. After debugging, the pressure block 63 is locked to press the first root 71 from the second direction Y, forming a stable multidimensional constraint with the locking force of the set screw 712 in the third direction Z. This effectively prevents the first root 71 from shifting due to vibration or stress relaxation during long-term operation, thereby significantly improving the stability and reliability of the entire stroke detection device during long-term operation while ensuring the motion decoupling function.

[0038] Please see Figure 2As shown, in an optional embodiment of the present invention, the grating support 60 is provided with a guide portion, and a linear bearing 50 arranged along the first direction X is provided between the guide portion and the housing 10 of the piezoelectric actuator. An anti-rotation portion for preventing the guide portion from rotating about an axis parallel to the first direction X is provided between the guide portion and the housing 10 of the piezoelectric actuator. In a specific embodiment, the anti-rotation portion may be, for example, a key and a keyway that cooperate between the guide portion and the housing 10. This invention constructs a highly accurate and stable pure translational reference for the grating strip 80 by providing a composite guiding mechanism consisting of a linear bearing 50 and an anti-rotation part for the grating support 60. The linear bearing 50 greatly reduces the frictional resistance of the grating support 60 moving along the first direction X, ensuring that it can respond sensitively and without jamming to the drive of the mover 20. The anti-rotation part effectively eliminates the torsion that may be caused by assembly stress or external interference by constraining the rotational degree of freedom of the grating support 60 about its axis of motion, ensuring the constant relative posture between the grating strip 80 and the fixed reading head 90, thereby providing a stable and reliable measurement environment for the reading head 90.

[0039] Please see Figure 2 As shown, in an optional embodiment of the present invention, the guide portion is constituted by the power output end 40 of the piezoelectric actuator. The present invention achieves both structural simplification and improved measurement accuracy by directly integrating the guide portion of the grating support 60 into the power output end 40 of the piezoelectric actuator. This design allows the grating support 60 and the power output end 40 to share the same high-precision linear bearing 50 guiding system, eliminating the need for a separate guiding structure for the grating support 60, simplifying the overall device, and reducing costs. More importantly, it fundamentally ensures that the grating strip 80 can move completely synchronously with the power output end 40, directly eliminating travel measurement deviations caused by errors in intermediate transmission links. This allows the travel detection benchmark to be directly established on the final power output end 40, achieving the most direct and accurate measurement of the actual output travel.

[0040] Please see Figure 5As shown, in an optional embodiment of the present invention, the grating bracket 60 is provided with a positioning surface 64 parallel to the first direction X, and one of the long sides of the grating strip 80 is in contact with the positioning surface 64. By providing a positioning surface 64 parallel to the first direction X on the grating bracket 60, the present invention provides a precise and reliable reference for the installation of the grating strip 80. This positioning surface 64 ensures that the grating strip 80 can be quickly and accurately aligned with the designed motion axis of the grating bracket 60 during installation. This not only simplifies the assembly process but also structurally ensures that the length direction of the grating strip 80 is highly parallel to the actual motion direction of the power output end 40, effectively avoiding Abbe error caused by installation tilt. This provides a stable and accurate measurement reference for the reading head 90, fundamentally guaranteeing the final accuracy of the stroke detection system.

[0041] It should be understood that the installation method of the flexible hinge 70 is not unique; for example, in Figure 8 In an alternative embodiment shown, two flexible hinges 70 are provided, and the two flexible hinges 70 are respectively connected to the two ends of the mover 20 along the first direction X. The grating support 60 includes a first part and a second part located at the two ends of the mover 20 along the first direction X. One flexible hinge 70 is connected to the first part, and the other flexible hinge 70 is connected to the second part. This alternative embodiment provides a motion decoupling mechanism different from the aforementioned dual-sided symmetrical drive by connecting two flexible hinges 70 to the two ends of the mover 20 along the first direction X and correspondingly connecting them to the two parts of the grating support 60. It utilizes the stretching and compressive deformation of the flexible hinges 70 to transmit unidirectional driving force and absorb multi-dimensional interference. When the mover 20 moves in one direction, the grating support 60 is driven by one of the hinges being stretched to its limit, while the other hinge drives the movement in the opposite direction. Although the mover 20 may experience a brief displacement delay when turning back due to the idle travel during the hinge deformation stage, it still successfully transmits the translational motion of the mover 20 in the first direction X to the grating support 60. At the same time, the flexibility of the hinges allows the mover 20 to perform necessary lateral and deflection micro-movements, thereby releasing harmful lateral stress.

[0042] In summary, this invention achieves the coordination and decoupling of the motion degrees of freedom of the mover 20 and the constraints of the grating measurement system by introducing a flexible hinge 70. Specifically, the flexible hinge 70, as a precise motion conversion interface, plays a core role in two aspects: Firstly, it has high rigidity in the first direction X, enabling it to transmit the reciprocating translational motion of the main body of the mover 20 to the grating support 60 with almost no loss and no lag, thereby driving the grating strip 80 to move stably along a preset precise straight trajectory. This fundamentally ensures that a constant optimal gap is maintained between the grating strip 80 and the fixed reading head 90, eliminating reading errors caused by gap fluctuations and guaranteeing the high precision and high reliability of the stroke detection system. Secondly, the flexible hinge 70 has appropriate flexibility in the plane perpendicular to the driving direction, allowing the mover 20 to perform slight adaptive deflection and displacement when subjected to unbalanced torque generated by the non-completely synchronous driving of the piezoelectric devices 30 on both sides. By releasing and effectively absorbing these harmful lateral torques and stresses on-site without transmitting them to the grating strip 80 and its guiding system, the system successfully avoids the jamming and sticking phenomena between the mover 20 and the guide rail caused by being completely rigidly constrained, without sacrificing measurement accuracy. Ultimately, it achieves the dual goals of high-precision stroke detection and long-term stable and smooth operation of the mover 20. The invention achieves efficient radial self-centering and precise axial positioning functions through the cooperation of the mounting groove 61, the protrusion 62 and the first root 71 with the lug 711. After the first root 71 is placed into the mounting groove 61, the mover 20 can be corrected to the design center position of the grating support 60 in the third direction Z by screwing in the set screw 712 to press against the protrusion 62. This process effectively compensates for the cumulative errors in parts processing and assembly, ensuring that a uniform initial gap is formed between the two sides of the mover 20 and the arm of the grating support 60, providing the necessary conditions for the smooth deflection of the mover 20.

[0043] The above embodiments are merely illustrative of the principles and effects of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or alter the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or alterations made by those skilled in the art without departing from the spirit and technical concept disclosed in the present invention should still be covered by the claims of the present invention.

[0044] Throughout this description, numerous specific details, such as examples of components and / or methods, are provided to provide a complete understanding of embodiments of the invention. However, those skilled in the art will recognize that embodiments of the invention may be practiced without one or more of these specific details or by other devices, systems, components, methods, parts, materials, components, etc. In other instances, well-known structures, materials, or operations have not been specifically shown or described in detail to avoid obscuring aspects of embodiments of the invention.

Claims

1. A travel detection device for a piezoelectric actuator, characterized in that, include: A grating support (60) is movably connected to the housing (10) of the piezoelectric actuator along a first direction (X); the grating support (60) is movably connected to the mover (20) of the piezoelectric actuator via a flexible hinge (70), the flexible hinge (70) being configured to transmit the movement of the mover (20) along the first direction (X) to the grating support (60), the first direction (X) being the direction of movement of the power output end (40) of the piezoelectric actuator driven by the mover (20); A grating strip (80) is mounted on the grating bracket (60), and the length direction of the grating strip (80) is parallel to the first direction (X); A reading head (90) is fixedly disposed inside the housing (10) of the piezoelectric actuator, and the reading head (90) is disposed opposite to the grating strip (80); The flexible hinge (70) includes two rigid roots and an elastic deformation portion (73) connected between the two roots. The length of the elastic deformation portion (73) in the first direction (X) is much greater than its thickness in the second direction (Y), which is perpendicular to the first direction (X). The two roots are respectively disposed on the grating support (60) and the mover (20) so that the grating support (60) and the mover (20) are connected to each other in a third direction (Z) by the flexible hinge (70), which is perpendicular to the first direction (X) and the second direction (Y) respectively.

2. The stroke detection device for the piezoelectric actuator according to claim 1, characterized in that, The grating support (60) includes a rectangular frame, which is sleeved on the outside of the mover (20) along the second direction (Y). The mover (20) includes a first side and a second side that are parallel to and opposite to the first direction (X). The rectangular frame includes a first arm opposite to the first side and a second arm opposite to the second side. At least two flexible hinges (70) are provided. At least one flexible hinge (70) is provided between the first arm and the first side, and at least one other flexible hinge (70) is provided between the second arm and the second side.

3. The stroke detection device for the piezoelectric actuator according to claim 2, characterized in that, The flexible hinge (70) is integrally formed with the mover (20), and the flexible hinge (70) is detachably connected to the grating bracket (60).

4. The stroke detection device for the piezoelectric actuator according to claim 3, characterized in that, The flexible hinge (70) is used to connect one root of the grating bracket (60) as a first root (71); the grating bracket (60) is provided with a mounting groove (61) extending along the third direction (Z), the mounting groove (61) extending along the second direction (Y) to one side surface of the grating bracket (60) to form a slot, and the mounting groove (61) has protrusions (62) on the two side walls opposite each other along the first direction (X), the first root (71) 1) Lugs (711) are provided at both ends in the first direction (X), the first root (71) is accommodated in the mounting groove (61), the lugs (711) are located on the side of the protrusion (62) away from the mover (20), the lugs (711) are provided with a threaded hole that passes through the third direction (Z), the threaded hole is provided with a set screw (712), and the set screw (712) abuts against the side of the protrusion (62) away from the mover (20).

5. The stroke detection device for the piezoelectric actuator according to claim 4, characterized in that, The mounting groove (61) has a pressure block (63) at the opening. The pressure block (63) is detachably fixed to the grating bracket (60) to close the opening and press the first root (71) along the second direction (Y).

6. The stroke detection device for the piezoelectric actuator according to claim 1, characterized in that, The grating support (60) is provided with a guide portion, and a linear bearing (50) arranged along the first direction (X) is provided between the guide portion and the housing (10) of the piezoelectric actuator. An anti-rotation portion is provided between the guide portion and the housing (10) of the piezoelectric actuator to prevent the guide portion from rotating about an axis parallel to the first direction (X).

7. The stroke detection device for the piezoelectric actuator according to claim 6, characterized in that, The guide portion is formed by the power output terminal (40) of the piezoelectric actuator.

8. The stroke detection device for the piezoelectric actuator according to claim 1, characterized in that, The grating support (60) is provided with a positioning surface (64) parallel to the first direction (X), and one of the long sides of the grating strip (80) is in contact with the positioning surface (64).

Images