Strain piezoelectric composite rotor balance

Abstract

The invention discloses a strain piezoelectric composite rotor balance, and belongs to the technical field of wind tunnel tests. Comprising a floating frame, a fixed frame and a force sensing unit. The force sensing unit is arranged between the floating frame and the fixed frame; a strain type force sensor, a piezoelectric type force sensor, a decoupling connecting rod and a sliding block capable of adjusting pre-tightening force are arranged in the force sensing unit; according to the scheme, simultaneous high-precision measurement of the static load and the high-frequency vibration load of the rotor wing is realized by using the characteristics of high static measurement precision of the strain type force sensor, wide dynamic measurement frequency band of the piezoelectric type force sensor and the decoupling effect of the decoupling connecting rod.

Description

Technical Field

[0001] The invention relates to the technical field of wind tunnel testing, and in particular to a strain piezoelectric composite rotor balance. Background Art

[0002] Wind tunnel testing is an important means of evaluating rotor aerodynamic performance and designing new rotor aerodynamic layouts, and plays an important role in the development of rotorcraft. When conducting wind tunnel testing of rotor aerodynamic performance, a rotor balance is usually used to measure the rotor load and obtain parameters such as rotor thrust and power.

[0003] When conducting wind tunnel tests on certain special rotor performance, it is necessary not only to measure the static load (0th order value) of the rotor, but also to measure the 2Nth order high-frequency harmonic load (N is the number of rotor blades) to evaluate the vibration characteristics of the rotor. Therefore, requirements are put forward for the dynamic measurement capability of the rotor balance.

[0004] Patent document CN111175014A discloses a balance system and method for accurate measurement of rotor aerodynamic loads. This solution is currently the most commonly used rotor balance system solution, and uses a number of strain-type force sensors to form a force measurement system. Strain-type force sensors have good measurement effects on static and low-frequency signals, but poor measurement effects on high-frequency signals, and may produce gain errors and phase drift. Therefore, conventional rotor balances work well when measuring static and low-frequency rotor load signals, but have large measurement errors when measuring high-frequency rotor load signals, and cannot meet the measurement requirements of high-frequency rotor vibration loads. Summary of the invention

[0005] The purpose of the present invention is to provide a strain piezoelectric composite rotor balance to address the above-mentioned shortcomings, thereby solving the problem that the existing conventional rotor balance has large measurement errors when measuring high-frequency rotor load signals and cannot meet the needs of high-frequency rotor vibration load measurement.

[0006] The present invention is achieved through the following scheme: A strain piezoelectric composite rotor balance comprises a floating frame, a fixed frame and a force sensitive unit; the force sensitive unit is arranged between the floating frame and the fixed frame, and the floating frame and the fixed frame are respectively provided with a main connecting plate and an auxiliary connecting plate connected to at least one group of force sensitive units; the force sensitive unit is provided with a strain force sensor, a piezoelectric force sensor, a decoupling connecting rod and a slider capable of adjusting the preload force.

[0007] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, a first assembly hole is arranged at the center position of the floating frame, and a second assembly hole adapted to the position of the first assembly hole is arranged on the fixed frame, and a rotor balance coordinate system OXYZ is established with the center position of the line connecting the first assembly hole and the second assembly hole as the origin; the OX axis is along the length direction of the floating frame, and coincides with the axis of the X-direction force sensitive unit; the OZ axis is along the width direction of the floating frame, and coincides with the center line of the axes of the two groups of Z-direction force sensitive units; the OY axis is along the center line direction of the first assembly hole and the second assembly hole; four groups of force sensitive units are arranged along the Y direction, and the four groups of force sensitive units are symmetrically arranged about the reference planes XOY and YOZ; two groups of force sensitive units are arranged along the Z direction, and the two groups of force sensitive units are symmetrically arranged about the reference plane YOZ; and one group of force sensitive units is arranged along the X direction.

[0008] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the main connecting plate and the auxiliary connecting plate provide support for two groups of force sensitive units along the Z direction and one group of force sensitive units along the X direction respectively; the main connecting plates are set to three, namely the first main connecting plate, the second main connecting plate and the third main connecting plate; the auxiliary connecting plates are set to three, namely the first auxiliary plate, the second auxiliary plate and the third auxiliary plate.

[0009] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the first main connecting plate and the first auxiliary plate are arranged correspondingly to form a first Z-direction support part; the second main connecting plate and the second auxiliary plate are arranged correspondingly to form a second Z-direction support part, and the first Z-direction support part and the second Z-direction support part are symmetrically arranged along the reference plane YOZ; the third main connecting plate and the third auxiliary plate are arranged correspondingly to form a first X-direction support part; the connecting direction of the third main connecting plate and the third auxiliary plate is collinear with the X-axis direction.

[0010] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, a first connecting hole connected to the force sensitive unit is arranged on the floating frame or the main connecting plate, and a second connecting hole connected to the force sensitive unit is arranged on the fixed frame or the auxiliary connecting plate; the force sensitive unit specifically includes a strain type force sensor, a first nut, a decoupling connecting rod, a second nut, a piezoelectric force sensor, a slider and a first screw; a gasket is arranged on the first screw, and a through hole for the first screw to pass through is arranged on the slider, the first screw is connected to the piezoelectric force sensor after passing through the first connecting hole and the slider, the decoupling connecting rod is respectively connected to the piezoelectric force sensor and the strain type force sensor, the connection between the decoupling connecting rod and the strain type force sensor is locked by the first nut, and the connection between the decoupling connecting rod and the piezoelectric force sensor is locked by the second nut.

[0011] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the slider includes a slide groove body, a wedge block and a second screw; a slide groove cavity cooperating with the wedge block is provided in the slide groove body, and a matching hole connected with the second screw is provided on the side wall of the slide groove body; the second screw passes through the matching hole and contacts the side wall of the wedge block.

[0012] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the slide trough body specifically includes a first side plate, a second side plate, a third side plate, a main side plate and a support plate; the first side plate, the second side plate, the third side plate and the main side plate are connected end to end to form a cavity structure with openings at both ends, the main side plate and the second side plate are symmetrically arranged, the first side plate and the third side plate are symmetrically arranged, the support plate is arranged at one end of the cavity structure, the main side plate protrudes from the first side plate, the second side plate and the third side plate, the thickness of the support plate is gradually increased along the direction from the main side plate to the second side plate, so that the slide trough cavity forms a wedge-shaped cavity, and a slide trough hole for the first screw to pass through is arranged in the center of the support plate.

[0013] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the wedge block includes a wedge inclined surface and a wedge vertical surface; the inclined surface angle of the wedge inclined surface and the inclined surface angle of the internal inclined surface of the support plate are within the equivalent friction angle, and the wedge inclined surface and the inclined surface inside the support plate are in contact with each other, the wedge vertical surface is in contact with the inner side walls of the first side plate and the third side plate, and a wedge hole for the first screw to pass through is also provided on the wedge inclined surface; the size of the wedge hole is adapted to the size of the first screw, and the first screw is arranged to pass through the wedge hole and the slide slot hole.

[0014] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, the first screw includes a cylindrical surface and a threaded surface; the cylindrical surface forms a small gap fit with the wedge block hole, and the threaded surface is arranged at the bottom of the cylindrical surface; the decoupling connecting rod includes an external thread section, a contraction section and an internal thread section; the external thread section and the internal thread section are respectively arranged on both sides of the contraction section, and the central axes of the external thread section, the contraction section and the internal thread section are collinearly arranged, and the diameter of the contraction section is not greater than the diameter of the external thread section or the internal thread section.

[0015] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, through the decoupling effect of the decoupling connecting rod, four groups of force sensitive units arranged along the Y direction sense and measure the longitudinal force Y, Mz, and Mx component loads; two groups of force sensitive units arranged along the Z direction sense and measure the lateral force Z and My component loads; and one group of force sensitive units arranged along the X direction senses and measures the axial force X component load.

[0016] Therefore, the composite rotor balance can measure the six-component load of the rotor. The corresponding relationship between the six-component load and the output signal of each strain force sensor is: (1) The corresponding relationship between the 6-component load and the output signal of each piezoelectric force sensor is: (2) Where: Y, X, Mz, Z, My, Mx – balance weight; Subscript "SG" - strain gauge force sensor signal; Subscript "PZ" - piezoelectric force sensor signal; ——Force sensor of the i-th group of force-sensitive units.

[0017] According to formula (1), the static load (0th order value) of the rotor can be obtained; according to formula (2), the 2Nth order high-frequency harmonic load of the rotor can be obtained. That is, the simultaneous high-precision measurement of the static load and high-frequency vibration load of some special rotor tests is achieved.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. This scheme proposes to set up a total of seven groups of force-sensitive units on a rotor balance. Each group of force-sensitive units includes a strain force sensor, a piezoelectric force sensor and a decoupling connecting rod. By using the high static measurement accuracy of the strain force sensor, the wide dynamic measurement frequency band of the piezoelectric force sensor and the decoupling effect of the decoupling connecting rod, the simultaneous high-precision measurement of the six-component static load and high-frequency vibration load of the rotor is achieved.

[0019] 2. This composite rotor balance solution accurately adjusts the preload force of each component of the force-sensitive unit by adjusting the height of the slider, ensuring that the decoupling link does not bend or twist, and only transmits the load along its own axis, reducing the interference caused by force transmission and improving the measurement effect of the rotor balance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a schematic diagram of the three-dimensional structure of the composite rotor balance of this scheme; Figure 2 This is a schematic diagram of the positions of the main connecting plate and the auxiliary connecting plate in this solution; Figure 3 Schematic diagram of the cross-sectional structure of the force-sensitive unit in this scheme; Figure 4 is a schematic diagram of the three-dimensional structure of the first screw in this solution; Figure 5 Schematic diagram of the three-dimensional structure of the decoupling connecting rod in this solution; Figure 6 Schematic diagram of the three-dimensional structure of the slider in this solution; Figure 7 It is a schematic diagram of the cross-sectional three-dimensional structure of the slider in this solution; Figure 8 It is a schematic diagram of the cross-sectional structure of the slider in this scheme; Fig. 9 This is a schematic diagram of the arrangement of the strain sensor and piezoelectric force sensor in this scheme; 1. Floating frame; 2. Fixed frame; 3. Force-sensitive unit; 4. Main connecting plate; 5. Auxiliary connecting plate; 11. First assembly hole; 21. Second assembly hole; 31. Strain-type force sensor; 32. First nut; 33. Decoupling connecting rod; 34. Second nut; 35. Piezoelectric force sensor; 36. Slider; 37. First screw; 38. Gasket; 41. First main connecting plate; 42. Second main connecting plate; 43. Third main connecting plate; 51. First auxiliary plate; 52. Second auxiliary plate; 53. Third auxiliary plate; 371. Threaded surface; 372. Cylindrical surface; 331. External thread segment; 332. Contraction segment; 333. Internal thread segment; 361. Slide body; 362. Wedge block; 363. Second screw; 364. Slide cavity; 365. Matching hole; 3611. First side plate; 3612. Second Side plate; 3613, third side plate; 3614, main side plate; 3615, support plate; 3616, slide slot hole; 3621, wedge block inclined surface; 3622, wedge block vertical surface; 3623, wedge block hole; 1001, first strain type force sensor; 1002, second strain type force sensor; 1003, third strain type force sensor; 1004, fourth strain type force sensor; 1005, fifth strain type force sensor; 1006, sixth strain type force sensor; 1007, seventh strain type force sensor; 2001, first piezoelectric force sensor; 2002, second piezoelectric force sensor; 2003, third piezoelectric force sensor; 2004, fourth piezoelectric force sensor; 2005, fifth piezoelectric force sensor; 2006, sixth piezoelectric force sensor; 2007, seventh piezoelectric force sensor. DETAILED DESCRIPTION

[0021] All features disclosed in this specification, or steps in all methods or processes disclosed, except mutually exclusive features and / or steps, can be combined in any manner.

[0022] Any feature disclosed in this specification (including any additional claims and abstract), unless otherwise stated, may be replaced by other alternative features that are equivalent or have similar purposes. That is, unless otherwise stated, each feature is only an example of a series of equivalent or similar features.

[0023] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by the terms "up", "down", "left", "right", etc. are based on the directions 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 predetermined direction, be constructed and operated in a predetermined direction, and therefore cannot be understood as a limitation on the present invention.

[0024] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first", "second", etc. may explicitly or implicitly include one or more of the features.

[0025] Example 1 like Figure 1 to Figure 8 The present invention provides a technical solution: A strain piezoelectric composite rotor balance, including at least but not limited to a floating frame 1, a fixed frame 2 and a force sensitive unit 3; the force sensitive unit 3 is arranged between the floating frame 1 and the fixed frame 2, and a main connecting plate 4 and an auxiliary connecting plate 5 connected to at least one group of force sensitive units 3 are respectively arranged on the floating frame 1 and the fixed frame 2, and a strain force sensor 31, a piezoelectric force sensor 35 and a slider 36 capable of adjusting the preload force are arranged in the force sensitive unit 3.

[0026] Based on the above structure, by arranging multiple groups of force-sensitive units 3 between the floating frame 1 and the fixed frame 2, it is possible to sense and measure component forces in multiple directions. A main connecting plate 4 and an auxiliary connecting plate 5 are arranged on the floating frame 1 and the fixed frame 2, which can provide a connection basis for the force-sensitive units 3 that are not directly connected to the floating frame 1 and the fixed frame 2. A strain-type force sensor 31 and a piezoelectric force sensor 35 are arranged on each group of force-sensitive units 3. The high static measurement accuracy of the strain-type force sensor 31 and the wide dynamic measurement bandwidth of the piezoelectric force sensor 35 are used to achieve simultaneous high-precision measurement of the static load and high-frequency vibration load of the rotor.

[0027] In this solution, the main connection plate and the auxiliary connection plate are arranged in pairs, at least three pairs, for the installation of the Z component, X component, and My component force sensitive units. The main connection plate and the floating frame can be one part, processed as a whole, or two parts, processed separately. The auxiliary connection plate and the fixed frame can be one part, processed as a whole, or two parts, processed separately.

[0028] As an example, a first assembly hole 11 is provided at the center position of the floating frame 1, and a second assembly hole 21 adapted to the position of the first assembly hole 11 is provided on the fixed frame 2, and a rotor balance coordinate system OXYZ is established between the first assembly hole 11 and the second assembly hole 21; the OX axis is along the length direction of the floating frame 1, and coincides with the axis of the X-direction force sensitive unit; the OZ axis is along the width direction of the floating frame 1, and coincides with the midline of the axes of the two groups of Z-direction force sensitive units; the OY axis is along the center line direction of the first assembly hole 11 and the second assembly hole 21.

[0029] Four groups of force-sensitive units 3 are arranged along the Y direction, and the four groups of force-sensitive units 3 are symmetrically arranged about the reference planes XOY and YOZ, and are sensitive to the longitudinal force Y, Mz, and Mx components; two groups of force-sensitive units 3 are arranged along the Z direction, and the two groups of force-sensitive units 3 are symmetrically arranged about the reference plane YOZ, and are sensitive to the lateral force Z and My components; one group of force-sensitive units 3 is arranged along the X direction, and is sensitive to the axial force X component.

[0030] Based on the above structure, this solution sets multiple groups of force-sensitive units 3 between the floating frame 1 and the fixed frame 2 along the X, Y, and Z axis directions, and measures the longitudinal force Y, Mz, and Mx components, the lateral force Z and My components, and the axial force X component through the force-sensitive units 3.

[0031] As an example, the main connecting plate 4 and the auxiliary connecting plate 5 provide support for two groups of force-sensitive units along the Z direction and one group of force-sensitive units along the X direction respectively.

[0032] The number of main connecting plates 4 is three, namely a first main connecting plate 41 , a second main connecting plate 42 and a third main connecting plate 43 .

[0033] The number of auxiliary connecting plates 5 is three, namely a first auxiliary plate 51 , a second auxiliary plate 52 and a third auxiliary plate 53 .

[0034] The first main connecting plate 41 and the first auxiliary plate 51 are arranged correspondingly to form a first Z-direction support portion; the second main connecting plate 42 and the second auxiliary plate 52 are arranged correspondingly to form a second Z-direction support portion; the first Z-direction support portion and the second Z-direction support portion are symmetrically arranged along the reference plane YOZ; the third main connecting plate 43 and the third auxiliary plate 53 are arranged correspondingly to form a first X-direction support portion, and the connecting line direction of the third main connecting plate 43 and the third auxiliary plate 53 is collinear with the X-axis of the coordinate system.

[0035] Based on the above structure, a more detailed connection structure is provided in the present solution. By setting a force-sensitive unit 3 in the first Z-direction support part and the second Z-direction support part, the lateral force Z and My components are measured, and by setting a force-sensitive unit 3 in the first X-direction support part, the axial force X component is measured.

[0036] As an example, a first connection hole connected to the force-sensitive unit 3 is provided on the floating frame 1 or the main connection plate 4 , and a second connection hole connected to the force-sensitive unit 3 is provided on the fixed frame 2 or the auxiliary connection plate 5 .

[0037] Based on the above structure, the force-sensitive unit 3 is stably fixed between the floating frame 1 and the fixed frame 2 through the first connecting hole and the second connecting hole.

[0038] As an example, the force sensitive unit 3 may specifically include a strain type force sensor 31, a first nut 32, a decoupling link 33, a second nut 34, a piezoelectric force sensor 35, a slider 36 and a first screw 37; a gasket 38 is provided on the first screw 37; a through hole is provided on the slider 36 for the first screw 37 to pass through, and the first screw 37 is connected to the piezoelectric force sensor 35 after passing through the first connecting hole and the slider 36, and the decoupling link 33 is respectively connected to the piezoelectric force sensor 35 and the strain type force sensor 31; the connection between the decoupling link 33 and the strain type force sensor 31 is locked by the first nut 32, and the connection between the decoupling link 33 and the piezoelectric force sensor 35 is locked by the second nut 34.

[0039] Based on the above structure, the strain type force sensor 31, the first nut 32, the decoupling link 33, the second nut 34, the piezoelectric force sensor 35, the slider 36, the first screw 37, and the gasket 38 are connected in series in sequence; the strain type force sensor 31 and the piezoelectric force sensor 35 are arranged at both ends of the decoupling link 33; the force transmission path of the rotor load on the force sensitive unit 3 is: floating frame 1→slider 36→piezoelectric force sensor 35→decoupling link 33→strain type force sensor 31→fixed frame 2; in this way, the static load of the rotor is sensed by the strain type force sensor 31, and the dynamic load of the rotor is sensed by the piezoelectric force sensor 35, thereby realizing simultaneous high-precision measurement of the static load and high-frequency vibration load of the rotor.

[0040] As an example, the slider 36 includes a slide groove body 361, a wedge block 362 and a second screw 363; a slide groove cavity 364 cooperating with the wedge block 362 is provided in the slide groove body 361; a matching hole 365 connected to the second screw 363 is provided on the side wall of the slide groove body 361, and the second screw 363 passes through the matching hole 365 and contacts the side wall of the wedge block 362.

[0041] The chute body 361 specifically includes a first side plate 3611, a second side plate 3612, a third side plate 3613, a main side plate 3614 and a support plate 3615; the first side plate 3611, the second side plate 3612, the third side plate 3613, and the main side plate 3614 are connected end to end to form a cavity structure with openings at both ends, the main side plate 3614 and the second side plate 3612 are symmetrically arranged, the first side plate 3611 and the third side plate 3613 are symmetrically arranged, and the support plate 3615 Set at one end of the cavity structure, the main side plate 3614 protrudes from the first side plate 3611, the second side plate 3612, and the third side plate 3613, and the thickness of the support plate 3615 is gradually increased along the direction from the main side plate 3614 to the second side plate 3612 on the support plate 3615, so that the slide groove cavity 364 forms a wedge-shaped cavity; a slide groove hole 3616 for the first screw 37 to pass through is set in the center of the support plate 3615, and the slide groove hole 3616 is an oblong hole.

[0042] The wedge block 362 may include a wedge block slope 3621 and a wedge block vertical surface 3622; the slope angle of the wedge block slope 3621 and the slope angle of the internal slope of the support plate 3615 are within the equivalent friction angle, and the wedge block slope 3621 and the internal slope of the support plate 3615 are in contact with each other, and the wedge block vertical surface 3622 is in contact with the inner walls of the first side plate 3611 and the third side plate 3613. A wedge block hole 3623 for the first screw 37 to pass through is also provided on the wedge block slope 3621. The size of the wedge block hole 3623 is adapted to the size of the first screw 37, and the first screw 37 is provided through the wedge block hole 3623 and the slide slot hole 3616.

[0043] Based on the above structure, in this scheme, since the bevel angle of the wedge block slope 3621 and the bevel angle of the internal slope of the support plate 3615 are within the equivalent friction angle, it has a self-locking function. When subjected to axial force (along the axial direction of the wedge block hole 3623), the wedge block 362 will not slide along the slide groove cavity 364, so the height of the slider 36 remains unchanged, ensuring that the various components of the force sensitive unit 3 are tightly connected and not loose. The height of the slider 36 in this scheme is achieved by adjusting the position of the wedge block 362, and the wedge block 362 can only move along the length direction of the slide groove in the slide groove cavity 364, and its position is accurately adjusted by the second screw 363.

[0044] As an example, the first screw 37 may include a cylindrical surface 372 and a threaded surface 371 ; the cylindrical surface 372 forms a small clearance fit with the wedge block hole 3623 , and the threaded surface 371 is arranged at the bottom position of the cylindrical surface 372 .

[0045] The first screw 37 passes through the first connection hole, the slide slot hole 3616, and the wedge hole 3623 on the floating frame 1 and is threadedly connected to the piezoelectric force sensor 35. The upper end of the decoupling link 33 is connected to the piezoelectric force sensor 35 through the external thread section 331 and is fastened with the second nut 34, and the lower end of the decoupling link 33 is connected to the strain force sensor 31 through the internal thread section 333 and is fastened with the first nut 32.

[0046] Based on the above structure, the force-sensitive unit 3 organically connects the piezoelectric force sensor 35 and the strain-type force sensor 31 into a whole through the first screw 37 and the decoupling link 33, so as to realize the simultaneous measurement of the static load and vibration load of the rotor by the force-sensitive unit.

[0047] As an example, the decoupling link 33 may include an external thread section 331, a contraction section 332 and an internal thread section 333; the external thread section 331 and the internal thread section 333 are respectively arranged on both sides of the contraction section 332; the central axes of the external thread section 331, the contraction section 332 and the internal thread section 333 are collinearly arranged, the diameter of the contraction section 332 is not larger than the diameter of the external thread section 331 or the internal thread section 333, the external thread section 331 is connected to the piezoelectric force sensor 35, and the internal thread section 333 is connected to the strain force sensor 31.

[0048] Specifically, the external thread section 331 is embedded in the piezoelectric force sensor 35 and connected to the piezoelectric force sensor 35 via the external thread; the internal thread section 333 is sleeved on the end of the strain force sensor 31 and connected to the strain force sensor 31 via the internal thread.

[0049] This solution achieves preload adjustment between the various components of the force-sensitive unit 3 by precisely adjusting the height of the slider 36, thereby ensuring a secure connection between the various components. At the same time, the contraction section 332 of the decoupling link 33 does not bend or twist, thereby avoiding additional force transmission interference that affects the measurement accuracy of the rotor balance.

[0050] Based on the structure of the above-mentioned strain piezoelectric composite rotor balance, through the decoupling effect of the decoupling connecting rod, four groups of force sensitive units arranged along the Y direction sense and measure the longitudinal force Y, Mz, and Mx component loads; two groups of force sensitive units arranged along the Z direction sense and measure the lateral force Z and My component loads; and one group of force sensitive units arranged along the X direction senses and measures the axial force X component load.

[0051] The decoupling effect of the decoupling link in this solution is the same as the content and effect disclosed in Patent No. CN111175014A, a balance system and method for accurate measurement of rotor aerodynamic loads, and this solution will not be repeated here.

[0052] Through the above structure, the composite rotor balance can measure the six components of the rotor load. The corresponding relationship between the six components of the load and the output signal of each strain force sensor 31 is: (1) The corresponding relationship between the 6-component load and the output signal of each piezoelectric force sensor 35 is: (2) Where: Y, X, Mz, Z, My, Mx – balance weight; Subscript "SG" - strain gauge force sensor signal; Subscript "PZ" - piezoelectric force sensor signal; ——Force sensor of the i-th group of force-sensitive units.

[0053] According to formula (1), the static load (0th order value) of the rotor can be obtained, and according to formula (2), the 2Nth order high-frequency harmonic load of the rotor can be obtained. That is, the simultaneous high-precision measurement of the static load and high-frequency vibration load of some special rotor tests is achieved; Fig. 9 1001~1007 refer to U1 respectively. SG ~U7 SG The location of the strain gauge force sensor, Fig. 9 2001~2007 refer to U1 respectively. PZ ~U7 PZ The location of the piezoelectric force sensor.

[0054] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A strain piezoelectric composite rotor balance, characterized in that: It includes a floating frame, a fixed frame and a force-sensitive unit; the force-sensitive unit is arranged between the floating frame and the fixed frame, and the floating frame and the fixed frame are respectively provided with a main connecting plate and an auxiliary connecting plate connected to at least one group of force-sensitive units; the force-sensitive unit is provided with a strain-type force sensor, a piezoelectric force sensor, a decoupling connecting rod and a slider capable of adjusting the preload force.

2. A strain piezoelectric composite rotor balance according to claim 1, characterized in that: A first assembly hole is provided at the center position of the floating frame, and a second assembly hole matched with the position of the first assembly hole is provided on the fixed frame. A rotor balance coordinate system OXYZ is established with the center position of the line connecting the first assembly hole and the second assembly hole as the origin; the OX axis is along the length direction of the floating frame and coincides with the axis of the X-direction force sensitive unit; the OZ axis is along the width direction of the floating frame and coincides with the center line of the axes of the two groups of Z-direction force sensitive units; the OY axis is along the center line direction of the first assembly hole and the second assembly hole; four groups of force sensitive units are provided along the Y direction, and the four groups of force sensitive units are symmetrically arranged about the reference planes XOY and YOZ; two groups of force sensitive units are provided along the Z direction, and the two groups of force sensitive units are symmetrically arranged about the reference plane YOZ; and one group of force sensitive units is provided along the X direction.

3. A strain piezoelectric composite rotor balance according to claim 2, characterized in that: The main connecting plate and the auxiliary connecting plate provide support for two groups of force-sensitive units along the Z direction and one group of force-sensitive units along the X direction respectively; there are three main connecting plates, namely the first main connecting plate, the second main connecting plate and the third main connecting plate; there are three auxiliary connecting plates, namely the first auxiliary plate, the second auxiliary plate and the third auxiliary plate.

4. A strain piezoelectric composite rotor balance as claimed in claim 3, characterized in that: The first main connecting plate and the first auxiliary plate are arranged correspondingly to form a first Z-direction supporting portion; the second main connecting plate and the second auxiliary plate are arranged correspondingly to form a second Z-direction supporting portion, and the first Z-direction supporting portion and the second Z-direction supporting portion are symmetrically arranged along the reference plane YOZ; the third main connecting plate and the third auxiliary plate are arranged correspondingly to form a first X-direction supporting portion; the connecting direction of the third main connecting plate and the third auxiliary plate is collinear with the X-axis direction.

5. A strain piezoelectric composite rotor balance as claimed in claim 4, characterized in that: The floating frame or the main connecting plate is provided with a first connecting hole connected to the force-sensitive unit, and the fixed frame or the auxiliary connecting plate is provided with a second connecting hole connected to the force-sensitive unit; the force-sensitive unit specifically includes a strain-type force sensor, a first nut, a decoupling link, a second nut, a piezoelectric force sensor, a slider and a first screw; the first screw is provided with a gasket, and the slider is provided with a through hole for the first screw to pass through. The first screw is connected to the piezoelectric force sensor after passing through the first connecting hole and the slider, and the decoupling link is respectively connected to the piezoelectric force sensor and the strain-type force sensor, and the connection between the decoupling link and the strain-type force sensor is locked by the first nut, and the connection between the decoupling link and the piezoelectric force sensor is locked by the second nut.

6. A strain piezoelectric composite rotor balance as claimed in claim 5, characterized in that: The sliding block includes a slide groove body, a wedge block and a second screw; a slide groove cavity cooperating with the wedge block is arranged in the slide groove body, and a matching hole connected with the second screw is arranged on the side wall of the slide groove body; the second screw passes through the matching hole and contacts with the side wall of the wedge block.

7. A strain piezoelectric composite rotor balance according to claim 6, characterized in that: The slide trough body specifically includes a first side plate, a second side plate, a third side plate, a main side plate and a support plate; the first side plate, the second side plate, the third side plate and the main side plate are connected end to end to form a cavity structure with openings at both ends, the main side plate and the second side plate are symmetrically arranged, the first side plate and the third side plate are symmetrically arranged, the support plate is arranged at one end of the cavity structure, the main side plate protrudes from the first side plate, the second side plate and the third side plate, the thickness of the support plate is gradually increased along the direction from the main side plate to the second side plate, so that the slide trough cavity forms a wedge-shaped cavity, and a slide trough hole for the first screw to pass through is arranged in the center of the support plate.

8. The strain piezoelectric composite rotor balance according to claim 7, characterized in that: The wedge block includes a wedge block slope and a wedge block vertical surface; the slope angle of the wedge block slope and the slope angle of the internal slope of the support plate are within the equivalent friction angle, and the wedge block slope and the internal slope of the support plate are in contact, the wedge block vertical surface is in contact with the inner side walls of the first side plate and the third side plate, and a wedge block hole for the first screw to pass through is also provided on the wedge block slope; the size of the wedge block hole is adapted to the size of the first screw, and the first screw is arranged to pass through the wedge block hole and the slide slot hole.

9. A strain piezoelectric composite rotor balance according to any one of claims 1 to 8, characterized in that: The first screw includes a cylindrical surface and a threaded surface; the cylindrical surface forms a small clearance fit with the wedge block hole, and the threaded surface is arranged at the bottom of the cylindrical surface; the decoupling connecting rod includes an external thread section, a contraction section and an internal thread section; the external thread section and the internal thread section are respectively arranged on both sides of the contraction section, and the central axes of the external thread section, the contraction section and the internal thread section are arranged collinearly, and the diameter of the contraction section is not greater than the diameter of the external thread section or the internal thread section.

10. A strain piezoelectric composite rotor balance according to any one of claims 2 to 8, characterized in that: The compound rotor balance measures the six-component load of the rotor. The corresponding relationship between the six-component load and the output signal of each strain force sensor is: The corresponding relationship between the 6-component load and the output signal of each piezoelectric force sensor is: Where: Y, X, Mz, Z, My, Mx – balance weight; Subscript "SG" - strain gauge force sensor signal; Subscript "PZ" - piezoelectric force sensor signal; ——force sensor of the i-th group of force-sensitive units; According to the above formula, the static load of the rotor and the Nth-order high-frequency harmonic load of the rotor are obtained.

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