JP7505976B2 - System and method for determining excitation force - Google Patents

Description

This disclosure relates to an excitation force determination system and an excitation force determination method.

Conventionally, it is known to obtain a transfer function of a structure based on the excitation force applied to the structure by a vibration exciter and the response of the structure to which the excitation force is applied. For example, in the sine wave sweep excitation method disclosed in Patent Document 1, a load cell and an accelerometer are provided on the structure. The load cell acquires the excitation force applied to the structure by the vibration exciter based on the supplied sine wave signal. The accelerometer acquires the acceleration as the response of the structure. The transfer function is obtained from these acquired results.

Japanese Patent Publication No. 3-079658

It is possible to use strain gauges instead of accelerometers to determine the transfer function of the rotating device as a structure. The force generated by the rotating device during operation can be identified using the determined transfer function. In this case, the response of the strain gauge needs to be obtained with high sensitivity even when the rotating device is operating at a low rotation speed, but Patent Document 1 does not disclose a specific configuration for achieving this.

The objective of the present disclosure is to provide an excitation force identification system and an excitation force identification method that can accurately identify the forces generated by a rotating device, even when the rotating device is operating at a low rotation speed.

According to at least one embodiment of the present invention, a vibration force identification system includes:
At least one strain body provided between the rotating device and the foundation;
At least one strain gauge provided on each of the strain bodies;
a vibration device for applying a vibration force to the rotating device based on an input sine sweep signal;
a force sensor for measuring the excitation force applied from the vibration device; and
a transfer function acquisition unit for acquiring a transfer function indicating a relationship between the excitation force as an input and a strain response of each of the strain gauges based on an output result from the force sensor and an output result from each of the strain gauges when the excitation device applies the excitation force;
and an excitation force identification unit for identifying the force generated in the rotating device during operation based on the output results from each of the strain gauges when the rotating device is operating and the transfer function acquired by the transfer function acquisition unit.

A method for identifying an excitation force according to at least one embodiment of the present invention includes the steps of:
A method for identifying an excitation force by an excitation force identifying system, comprising:
a transfer function acquisition step of acquiring a transfer function indicating a relationship between the excitation force as an input and a strain response of each of the strain gauges based on an output result from the force sensor of the excitation force specifying system, the excitation force specifying system including at least one strain body provided between a rotating device and a foundation, at least one strain gauge provided on each of the strain bodies, an excitation device for applying an excitation force to the rotating device based on an input sine sweep signal, and a force sensor for measuring the excitation force applied from the excitation device and an output result from each of the strain gauges when the excitation device applies the excitation force;
and an excitation force identification process for identifying the force generated in the rotating device during operation based on the output results from each of the strain gauges when the rotating device is operating and the transfer function acquired in the transfer function acquisition process.

According to some embodiments, it is possible to provide an excitation force identification system and an excitation force identification method that can accurately identify the forces generated by a rotating device even when the rotating device is operating at a low rotation speed.

FIG. 1 is a front view of an excitation force identification system according to an embodiment. FIG. 1 is a plan view of an excitation force identification system according to an embodiment. FIG. 2 is a perspective view showing a point of action to which an excitation force is applied in a rotation device according to one embodiment. FIG. 1 illustrates a strain response from a strain gauge according to one embodiment. FIG. 4 is a diagram showing a transfer function acquired by a transfer function acquisition unit according to an embodiment; FIG. 4 is a diagram illustrating a strain response spectrum during operation of a rotating device according to an embodiment. 1A and 1B are diagrams illustrating the results of identifying forces occurring during operation of a rotational device according to an embodiment. FIG. 2 is a block diagram showing the functions of an excitation force specifying system according to an embodiment. 1 is a process diagram illustrating an excitation force specifying method according to an embodiment.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as the embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the present invention.
For example, expressions expressing relative or absolute configuration, such as "in a certain direction,""along a certain direction,""parallel,""orthogonal,""center,""concentric," or "coaxial," not only express such a configuration strictly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained.
For example, expressions indicating that things are in an equal state, such as "identical,""equal," and "homogeneous," not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained.
For example, expressions describing shapes such as a rectangular shape or a cylindrical shape do not only refer to rectangular shapes, cylindrical shapes, etc. in the strict geometric sense, but also refer to shapes that include uneven portions, chamfered portions, etc., to the extent that the same effect is obtained.
On the other hand, the expressions "comprise,""include,""have,""includes," or "have" of one element are not exclusive expressions excluding the presence of other elements.

FIG. 1 is a front view of a vibration force specifying system 1 according to an embodiment, and FIG. 2 is a plan view of the vibration force specifying system 1 according to an embodiment.
The excitation force specifying system 1 of one embodiment is configured to specify a force generated in a rotation device 7. The rotation device 7 of one embodiment includes a rotation shaft 7a and a housing 7b that supports the rotation shaft 7a.
In one embodiment, the rotating device 7 is a compressor. As a more specific example, the rotating device 7 is a reciprocating compressor. The rotating device 7 may be, for example, a rotary compressor.

In one embodiment, the excitation force identification system 1 includes at least one strain body 10 provided between the rotating device 7 and the foundation 6, at least one strain gauge 20 provided on each of the strain bodies 10, a vibration device 30 for applying an excitation force to the rotating device 7, a force sensor 35 for measuring the excitation force, a transfer function acquisition unit 40 for acquiring the relationship between the excitation force as an input and the strain response of each strain gauge 20, and an excitation force identification unit 50 for identifying the force generated in the rotating device 7 during operation.
1 and 2, in one embodiment, the connection state of some of the multiple strain gauges 20 to the transfer function acquisition unit 40 is omitted. The number of each of the strain body 10 and the strain gauge 20 may be one.
An example of a specific configuration of the strain element 10 and the strain gauge 20 will be described later.

In one embodiment, the excitation force applied from the vibration device 30 to the rotation device 7 is based on the sine sweep signal 34 input to the vibration device 30. That is, the period of the excitation force changes continuously according to the input sine sweep signal 34. Note that the vibration device 30 in one embodiment generates the excitation force by alternately switching the direction of the force applied to the rotation device 7 between one side and the other side.
In one embodiment, each strain gauge 20 is configured to detect a strain generated in the strain body 10 when the excitation force is applied. When the excitation force is applied, the transfer function acquisition unit 40 acquires a transfer function based on the output result from the strain gauge 20 and the output result from the force sensor 35.
Moreover, in one embodiment, each strain gauge 20 is also configured to detect a strain generated in the strain body 10 during operation of the rotating device 7. During operation of the rotating device 7, the excitation force identifying unit 50 identifies the force generated in the rotating device 7 based on the output results from the strain gauges 20 and the acquired transfer function.
In one embodiment, both the vibration device 30 and the force sensor 35 are disconnected from the rotation device 7 during operation of the rotation device 7 .

式（２）において、ｎはひずみゲージ２０の個数を示す自然数であり、ｍは回転装置７に付与される加振力の個数（後述の作用点５の個数と一致する）を示す自然数である。
一実施形態では、伝達関数取得部４０は、ひずみゲージ２０の応答スペクトルであるε（ω）と、加振装置３０が作動するときのフォースセンサ３５の出力結果であるＦ（ω）と、式（２）とに基づき、少なくとも一つの伝達関数を取得する（このときの式（２）のωは、加振装置３０から付与される加振力の周波数となる）。
一実施形態では、取得される伝達関数の個数はｎにｍを乗じた値である。一例として、伝達関数の個数は行列としてのＨ（ω）を構成する成分の個数である。
式（１）を変形すると式（３）のようになる。式（３）のＨ_ｉｎｖ（ω）はＨ（ω）の逆行列である。
Ｆ（ω）＝Ｈ_ｉｎｖ（ω）ε（ω）・・・式（３）
加振力特定部５０は、伝達関数取得部４０により取得されたＨ（ω）と、回転装置７が動作するときのひずみゲージ２０の出力結果であるε（ω）と、式（３）とに基づき、Ｆ（ω）を特定する（このときの式（３）のωは回転装置７の回転数を示す）。特定されるＦ（ω）は、加振力が付与される作用点５（後述）で生じている力である。加振装置３０の加振位置から得られる規定の慣性テンソルＩを用いると、回転装置７の中心位置で生じる力Ｆ’は式（４）によって表される。
Ｆ’（ω）＝Ｆ（ω）Ｉ・・・式（４）
加振力特定部５０は、式（４）に基づきＦ’（ω）を特定する。
以上のＦ（ω）又はＦ’（ω）が、加振力特定部５０によって特定される回転装置７で生じる力となる。 The principle by which the excitation force identifying unit 50 identifies the excitation force is as follows.
When the frequency is ω, the response spectrum of the strain gauge 20 is ε, the transfer function (response function matrix) acquired by the transfer function acquisition unit 40 is H, and the excitation force spectrum is F, the following equation (1) is established.
ε(ω)=H(ω)F(ω)...Equation (1)
The components of the determinant in equation (1) are specified as in equation (2).

In equation (2), n is a natural number indicating the number of strain gauges 20, and m is a natural number indicating the number of excitation forces applied to the rotating device 7 (which corresponds to the number of action points 5 described below).
In one embodiment, the transfer function acquisition unit 40 acquires at least one transfer function based on ε(ω), which is the response spectrum of the strain gauge 20, F(ω), which is the output result of the force sensor 35 when the vibration device 30 is operating, and equation (2) (ω in equation (2) here is the frequency of the vibration force applied by the vibration device 30).
In one embodiment, the number of transfer functions obtained is n multiplied by m. As an example, the number of transfer functions is the number of elements constituting H(ω) as a matrix.
Equation (1) is transformed into equation (3): H _inv (ω) in equation (3) is the inverse matrix of H(ω).
F(ω)=H _inv (ω) ε(ω)...Equation (3)
The excitation force identifying unit 50 identifies F(ω) based on H(ω) acquired by the transfer function acquiring unit 40, ε(ω) which is the output result of the strain gauge 20 when the rotating device 7 is in operation, and equation (3) (ω in equation (3) indicates the rotation speed of the rotating device 7). The identified F(ω) is the force occurring at the action point 5 (described later) to which the excitation force is applied. Using a specified inertia tensor I obtained from the excitation position of the vibration device 30, the force F' occurring at the center position of the rotating device 7 is expressed by equation (4).
F'(ω)=F(ω)I...Equation (4)
The excitation force determining unit 50 determines F'(ω) based on the formula (4).
The above F(ω) or F′(ω) is the force generated in the rotating device 7 identified by the excitation force identifying unit 50 .

A plurality of strain bodies 10 according to one embodiment are provided. The shape of the strain bodies 10 can be freely designed according to the excitation force identification system 1. The number of strain bodies 10 can also be freely adjusted. As an example, the number of strain bodies 10 is four. The number may be one, two, three, five or more.
Each of the flexure bodies 10 according to the embodiment includes flexure bodies 10a and 10b that are different from each other.
The flexure body 10a in one embodiment is fixed to the foundation 6. As an example, the flexure body 10a is provided at a position that avoids the housing 7b of the rotating device 7 in a plan view. For example, the flexure body 10a may be provided at a position displaced from the housing 7b on the radial outer side of the rotating shaft 7a. Alternatively, the flexure body 10a may be provided at a position displaced from the housing 7b on the axial outer side of the rotating device 7.
In one embodiment, the flexure body 10a extends in the vertical direction. More specifically, the flexure body 10a is rod-shaped. The flexure body 10a has an upper end 11a, a lower end 11b, and a central portion 11c. The upper end 11a and the lower end 11b have the same diameter, while the central portion 11c has a smaller diameter than the upper end 11a and the lower end 11b. In this case, the central portion 11c is more likely to bend than the upper end 11a and the lower end 11b. The upper end 11a, the lower end 11b, and the central portion 11c may be separate members, or may be formed of a single member. The flexure body 10a may be a cylinder having the same outer diameter in the vertical direction, or may be a prismatic column instead of a cylinder.
In one embodiment, the flexure body 10b connects the flexure body 10a and the rotation device 7. In one embodiment, the flexure body 10b is a plate extending in the horizontal direction. In this case, the flexure body 10b is easily deflected in the vertical direction. In one embodiment, the flexure body 10b has one end fixed to the flexure body 10a and the other end to which the rotation device 7 is fixed.
In other embodiments, the strain element 10 may be a single member.

In one embodiment, the fixing structure of the base 6, the strain bodies 10a and 10b, and the rotation device 7 is as follows.
A male screw is formed on the lower end 11b of the strain body 10a, and a nut (not shown) is fixed to the foundation 6. The strain body 10a is fixed to the foundation 6 by screwing the lower end 11b into the nut.
A male thread is also formed on the upper end 11a of the flexure body 10a, and a nut (not shown) is screwed into it. The upper end 11a is inserted into a hole formed in one end of the flexure body 10b, and the flexure body 10b abuts against the nut from above. Then, another nut is screwed onto the upper end 11a and tightened until it abuts against the flexure body 10b from above. As a result, the upper end 11a is fixed to one end of the flexure body 10b.
Holes (not shown) are formed in the other end of the strain body 10b and in the housing 7b of the rotation device 7. After the position of the rotation device 7 is adjusted so that the positions of these holes are aligned vertically, bolts (not shown) are inserted into these holes. Then, a nut is screwed onto the shaft of the bolt and tightened until it presses against either the strain body 10b or the rotation device 7. This fixes the rotation device 7 to the strain body 10b.
In one embodiment, the fixed positions of the strain body 10a and the strain body 10b and the fixed positions of the strain body 10b and the rotating device 7 may be arranged along the axial direction of the rotating device 7 or along the radial direction of the rotating shaft 7a.

According to one embodiment, a plurality of strain gauges 20 are provided. In one embodiment, all of these strain gauges 20 are provided outward in a plan view (on the side of the arrow T in FIG. 2 ) from the housing 7b in a radial direction based on the rotation shaft 7a of the rotating device 7. Note that at least one strain gauge 20 may be provided at a position overlapping with the housing 7b in a plan view.
According to an embodiment, the at least one strain gauge 20 includes strain gauges 20a, 20b, and 20c. For example, when the number of strain bodies 10 on which the strain gauges 20 are provided is four, four sets of strain gauges 20a, 20b, and 20c (total of 12) are provided.
In one embodiment, the strain gauges 20a and 20b are provided on the flexure body 10a, and the strain gauge 20c is provided on the flexure body 10c. More specifically, as an example, the strain gauges 20a and 20b are provided on the central portion 11c of the flexure body 10a. The strain gauge 20c is provided between one end and the other end of the flexure body 10c extending in the horizontal direction.
In one embodiment, the strain gauges 20a, 20b are provided in each of the flexure bodies 10a at positions offset from each other by 90 degrees (or 270 degrees) around the axis of the flexure body 10a. In one embodiment, the strain gauges 20a, 20b are positioned at the same height as each other, but may be positioned at different heights from each other.
In one embodiment, the strain gauges 20a, 20b and the strain gauge 20c extend in directions intersecting each other. More specifically, as an example, the strain gauges 20a, 20b extend in the vertical direction, and the strain gauge 20c extends in the horizontal direction.
In another embodiment, the strain gauge 20c may extend at an angle with respect to the horizontal direction and the vertical direction. Even in this case, the extension direction of the strain gauge 20c intersects with the extension directions of the strain gauges 20a and 20b. The extension directions of the strain gauges 20a and 20b may also intersect with each other.
In one embodiment, the thickness directions of the strain gauges 20a, 20b, and 20c intersect with each other. That is, the directions in which the strain gauges 20a, 20b, and 20c are likely to bend intersect with each other. In one embodiment, the three thickness directions are perpendicular to each other.
In other embodiments, each strain body 10a may be provided with only one of the strain gauges 20a and 20b, or the strain gauge 20 may not include the strain gauge 20c.

In the following description, the X, Y, and Z directions may be used, which are mutually orthogonal. In one embodiment, the X and Y directions are horizontal directions, and the Z direction is parallel to the up-down direction. In one embodiment, the Y direction is parallel to the axial direction of the rotation device 7.
In one embodiment, the thickness directions of the strain gauges 20a, 20b, and 20c are parallel to the X direction, Y direction, and Z direction, respectively.
When the vibration device 30 applies an excitation force to the rotation device 7 or when the rotation device 7 operates, a force and a moment are generated in the rotation device 7. Each of these forces and moments has a vector component in at least one of the X direction, the Y direction, and the Z direction. Each strain body 10 according to one embodiment is distorted by the combined action of the above forces and moments, and the output result of the strain gauge 20 reflects this combined action.

Figure 3 shows the point of action 5 to which the excitation force is applied from the excitation device 30 in the rotation device 7 according to one embodiment. In Figure 3, the rotation axis 7a is shown by a two-dot chain line. Also, in Figure 3, the strain body 10 and the strain gauge 20 are shown in a simplified form (the same applies to Figures 4 and 5).

In one embodiment, there are multiple points of application 5 at which the excitation force is applied to the rotating device 7 .
In one embodiment, the multiple action points 5 include multiple action points 5X, multiple action points 5Y, and multiple action points 5Z. In one embodiment, an excitation force parallel to the X-axis is applied to each of the action points 5X. Similarly, an excitation force parallel to the Y-axis direction is applied to each of the action points 5Y, and an excitation force parallel to the Z-axis direction is applied to each of the action points 5Z.
In one embodiment, the total number of application points 5 is the same as the number of strain gauges 20. In one embodiment, the total number of application points 5X, 5Y, and 5Z is 12, which is the same as the total number of strain gauges 20a, 20b, and 20c.
In another embodiment, the action point 5 may include at least one of the action points 5X, 5Y, and 5Z. In addition, an excitation force inclined in the X direction and the Z direction, or an excitation force inclined in the X direction and the Y direction may be applied to the action point 5X. In addition, the number of action points 5 may be different from the number of strain gauges 20.
In one embodiment, the number of action points 5 corresponds to the number of excitation forces applied by the vibration device 30 to the rotation device 7. The transfer function acquisition unit 40 acquires a plurality of transfer functions for each of the plurality of action points 5 to which the excitation forces are applied.

In one embodiment, the connection structure of the action points 5, the force sensor 35, and the vibration device 30 is as follows. A screw hole is formed in a portion of the housing 7b corresponding to each action point 5, and one end of the rod-shaped force sensor 35 is screwed into this screw hole. In addition, a rod-shaped operating part provided on the vibration device 30 is screwed into a screw hole formed in the other end of the force sensor 35. As a result, at each action point 5, the rod-shaped operating part is fixed coaxially with the force sensor 35, and the vibration device 30 is connected to the rotation device 7 via the force sensor 35. In this case, since the force sensor 35 is directly connected to the housing 7b and the rotation device 7, the vibration force applied from the vibration device 30 to the rotation device 7 can be directly measured. Therefore, the vibration force is measured with high accuracy.
In addition, while the number of "each action point 5" means one or more, it is preferable that the number of action points 5 is three or more, and it is more preferable that at least one each of action points 5X, 5Y, and 5Z is included in the action points 5.
In one embodiment, the vibration device 30 is supported by another member during operation.

4 shows the strain response output from each strain gauge 20 when an excitation force is applied to each application point 5. Although detailed illustration is omitted, the strain response according to one embodiment can be represented by a graph with time on the horizontal axis and the amount of strain on the vertical axis.
In one embodiment, when four sets of strain gauges 20a, 20b, and 20c (12 in total) are provided, a total of 12 strain responses are output each time an excitation force is applied to any of the multiple action points 5. For example, when the number of action points 5 is 12 (four action points 5X, 5Y, and 5Z), a total of 144 strain responses are output. At this time, the output results from the force sensor 35 are 12, which is the same as the number of action points 5. When the above-mentioned formula (2) is applied to this embodiment, m is 12 because there are four action points 5X, 5Y, and 5Z. In other words, F _X-1 , F _X-2 , F _X-3 , F _X-4 , F _Y-1 , ..., F _Z-4 indicating the output results of the force sensor 35 become the matrix elements of the second term on the right side of formula (2). Furthermore, if there are four sets of strain gauges 20a, 20b, and 20c (12 in total), n in formula (2) is 12. That is, ε _1-1 , ε _1-2 , ε _1-3 , ε _2-1 , ..., ε _4-3 indicating the output results of strain gauge 20 become the matrix elements on the left side of formula (2). In this case, the number of transfer functions acquired based on formula (2) is 144.

5 shows a graph of a transfer function acquired by the transfer function acquisition unit 40 according to an embodiment. In the graph shown in FIG. 5, the horizontal axis indicates the frequency of the excitation force, and the vertical axis indicates the strain response of the strain gauge 20 per unit force.
In the example of Fig. 5, a graph of the transfer function corresponding to each of the four sets of strain gauges 20a, 20b, and 20c (12 in total) is obtained for each of the four points of application 5Y. "1-a", "1-b", and "1-c" in Fig. 5 correspond to one of the four sets of strain gauges 20a, 20b, and 20c, and the number of transfer functions obtained at each point of application 5Y is 12.
Although detailed illustration is omitted, a transfer function is similarly obtained for each of the action points 5X and 5Y.

6 shows the strain response of the strain gauges 20 when the rotating device 7 operates in one embodiment. "1-a", "1-b", and "1-c" in FIG. 6 correspond to one of the four sets of strain gauges 20a, 20b, and 20c.
In one embodiment, data in which time and strain amount are associated with each other is acquired from each strain gauge 20, and this data is subjected to FFT processing (fast Fourier transform processing) to acquire the strain response spectrum of Fig. 6. The first graph in Fig. 6 shows, as an example, that there are two resonance frequencies where the strain amount is large.

7 is a graph showing the force identified by the excitation force identifying unit 50 based on the output result of the strain gauge 20 when the rotating device 7 is operating in one embodiment. In one embodiment, the graph is generated by extracting and plotting the operating order components of F'(ω) in equation (4). In one embodiment, a graph is shown in which the first order rotational component and the second order rotational component are extracted in each of the X direction, Y direction, and Z direction. In another embodiment, a graph may be created in which third order or higher rotational components are extracted.
Although detailed illustration is omitted, in one embodiment, a moment acting on the rotation device 7 may be identified based on the identified F'(ω). In one embodiment, the moment may be calculated for each of the first rotation component and the second rotation component in the X direction, the Y direction, and the Z direction. The moment may be calculated for each of the third or higher rotation components.

FIG. 8 is a block diagram showing the functions of the vibration force specifying system 1 according to an embodiment.
The vibration force specification system 1 of one embodiment includes a control unit 70, a vibration system 80 that operates in response to a command from the control unit 70, and a measurement target system 90.

The control unit 70 in one embodiment is a device including a processor unit. The processor included in the processor unit is configured to load a read program into a memory and execute instructions included in the loaded program. The processor is, for example, a CPU, a GPU, an MPU, a DSP, various other arithmetic devices, or a combination of these. The processor may be realized by an integrated circuit such as a PLD, an ASIC, an FPGA, or an MCU.
The control unit 70 includes a command unit 71 that sends a command to the vibration system 80 to start operation, a data logger 75 that records the output results of the force sensor 35 and the strain body 10, a transfer function acquisition unit 40, and a vibration force identification unit 50.

The vibration system 80 of one embodiment includes a signal generator 81 that generates a signal in response to receiving a command from the command unit 71, an amplifier 82 that inputs a sine sweep signal 34 obtained by amplifying the signal generated by the signal generator 81 to the vibration device 30, the vibration device 30, and a force sensor 35. The output result of the force sensor 35 is output to a data logger 75.

The measurement target system 90 includes a rotating device 7, at least one strain body 10, and a drive motor 88. In one embodiment, the drive motor 88 is connected to the rotating device 7 when the rotating device 7 is operated. The drive motor 88 is driven by power supplied from an inverter 94. The rotating device 7, which receives driving force from the drive motor 88, operates while changing the rotation speed. In one embodiment, when the rotating device 7 is a compressor, the rotating device 7 operates with the intake and exhaust ports of the rotating device 7 open. This makes it possible to prevent the pressure of the gas inside the rotating device 7 from affecting the output result of the strain gauge 20.

FIG. 9 shows a process diagram of an exciting force specifying method using the exciting force specifying system 1 according to one embodiment.
First, in a transfer function acquisition step (S11), the transfer function acquisition unit 40 acquires a transfer function based on the output result from the force sensor 35 and the output result from each strain gauge 20 when the vibration device 30 applies a vibration force to the rotation device 7. In one embodiment, when there are multiple action points 5, the vibration device 30 applies a vibration force to each action point 5 in sequence.
In the subsequent excitation force identification process (S13), the excitation force identification unit 50 identifies the force generated in the rotating device 7 during operation based on the output results from each strain gauge 20 when the rotating device 7 is operating and the transfer function acquired by the transfer function acquisition unit 40.
Through the above steps, the force generated by the rotation device 7 is identified.

Below, we will provide an overview of the excitation force identification system 1 and the excitation force identification method according to several embodiments.

(1) The vibration force specifying system 1 according to at least one embodiment of the present invention includes:
At least one strain body 10 provided between the rotation device 7 and the foundation 6;
At least one strain gauge 20 provided on each of the strain generating bodies 10;
a vibration device 30 for applying a vibration force to the rotating device 7 based on an input sine sweep signal 34;
A force sensor 35 for measuring the excitation force applied from the vibration device 30;
a transfer function acquisition unit 40 for acquiring a transfer function indicating a relationship between the excitation force as an input and a strain response of each of the strain gauges 20 based on an output result from the force sensor 35 and an output result from each of the strain gauges 20 when the excitation device 30 applies the excitation force;
and an excitation force identification unit 50 for identifying the force generated in the rotating device 7 during operation based on the output results from each of the strain gauges 20 when the rotating device 7 is operating and the transfer function acquired by the transfer function acquisition unit 40.
Incidentally, the number of each of the above-mentioned "each strain body 10" and "each strain gauge 20" indicates one or more.

According to the above configuration (1), each strain gauge 20 is provided on the strain body 10 between the rotating device 7 and the foundation 6. This allows the strain body 10 to be distorted with good sensitivity even when the frequency band of the excitation force applied by the vibration device 30 is low. Therefore, the strain gauge 20 can react with good sensitivity, and the transfer function acquisition unit 40 can acquire a highly reliable transfer function. Therefore, even when the rotating device 7 operates at a low rotation speed, the force generated by the rotating device 7 during operation can be identified with good accuracy.
By accurately identifying the forces generated when the rotating device 7 operates, for example, when designing a foundation 6 for installing the rotating device 7, the shape and material of the foundation 6 can be selected so that resonance does not occur in the structure including the rotating device 7 and foundation 6, and a vibration-proof design can be implemented.
Here, a method is considered in which impulse excitation is performed instead of sweep excitation, and the force in the rotating device 7 is identified based on the output result of an acceleration pickup instead of the strain gauge 20. More specifically, as an example, a method is considered in which the response when impact excitation using an impulse hammer is applied to the rotating device 7 is identified based on the output result of an acceleration pickup, and a transfer function is obtained based on the output result. However, the inventor has confirmed through experiments that the transfer function obtained by the above method does not have a coherence function value approaching 1 in a relatively low frequency band. In other words, the lower the frequency band of the applied force, the lower the reliability of the obtained transfer function, and the lower the accuracy of the force identified by the excitation force identifying unit 50. This problem is considered to be partly due to restrictions on the measurement characteristics and installation method of commercially available acceleration pickups. In this regard, according to the configuration (1), a transfer function with higher reliability than the conventional one can be obtained for the reasons already described, and various forces can be identified with high accuracy. The coherence function is a variable between 0 and 1 indicating the reliability of the transfer function, with the closer the value is to 1, the higher the reliability of the transfer function.
In addition, since the shape of the strain body 10 according to the embodiment can be freely designed, it is possible to adopt a shape, material, arrangement position, etc. of the strain body 10 that generates distortion with good sensitivity while ensuring the necessary strength. Therefore, even when the frequency band of the excitation force and the rotation speed of the rotating device 7 are low, the strain body 10 can react with good sensitivity, so that various forces generated by the rotating device 7 can be accurately identified.

(2) In some embodiments, in the configuration of (1),
The at least one strain gauge 20 includes a plurality of strain gauges 20;
The transfer function acquisition unit 40 is configured to acquire a plurality of transfer functions corresponding to each of the plurality of strain gauges 20 .

According to the above configuration (2), the excitation force identification unit 50 identifies the force generated in the rotating device 7 based on multiple transfer functions corresponding to multiple strain gauges 20. Therefore, the force generated in the rotating device 7 during operation can be identified with high accuracy.

(3) In some embodiments, in the configuration of (2),
The at least one strain gauge 20 includes two strain gauges 20a, 20c each extending in a direction intersecting each other.

According to the configuration (3) above, even if the force generated by the rotating device 7 has components in multiple directions, at least one of the strain gauges 20a, 20c can respond to this force with good sensitivity. Therefore, the excitation force identification unit 50 can accurately identify the force generated by the rotating device 7 during operation.

(4) In some embodiments, in any one of the configurations (1) to (3) above,
Each of the strain gauges 20 is provided on the outer side of the housing 7b of the rotating device 7 in a plan view in a radial direction based on the rotating shaft 7a of the rotating device 7.

According to the above configuration (4), the strain body 10 on which the strain gauge 20 is provided is separated from the center of gravity of the rotating device 7, so that the strain body 10 can be distorted with good sensitivity in response to various forces generated by the rotating device 7. This allows the excitation force identification unit 50 to accurately identify the forces generated by the rotating device 7 during operation.

(5) In some embodiments, in any one of the configurations (1) to (4) above,
The transfer function acquisition unit 40 is configured to acquire a plurality of the transfer functions for each of a plurality of action points 5 to which the excitation force is applied in the rotating device 7 .

According to the above configuration (5), the excitation force identification unit 50 identifies the force generated in the rotating device 7 based on multiple transfer functions for each of the multiple action points 5 to which the excitation force is applied. Therefore, the force generated in the rotating device 7 during operation can be accurately identified.

(6) In some embodiments, in the configuration of (5),
The at least one strain gauge 20 includes a plurality of strain gauges 20;
the transfer function acquisition unit 40 is configured to acquire a plurality of transfer functions for each of the plurality of action points 5 to which the excitation force is applied in the rotation device 7,
The number of the strain gauges 20 is the same as the number of the application points.

According to the configuration (6) above, since it is not necessary to add a dummy component to the matrix of the first term on the left side or the second term on the right side of equation (2) to perform the calculation process, the load of the calculation process is reduced. Therefore, the process of the transfer function acquisition unit 40 acquiring the transfer function is accelerated.

(7) In some embodiments, in any one of the configurations (1) to (6) above,
The strain body 10 is provided between the reciprocating compressor, which is the rotating device 7 , and the foundation 6 .

According to the configuration (7) above, the excitation force identification unit 50 can accurately identify the forces that occur during the operation of the reciprocating compressor, which tends to have a relatively low rotation speed.

(8) A vibration force identification method according to at least one embodiment of the present invention includes:
A method for identifying an excitation force by an excitation force identifying system, comprising:
a transfer function acquisition step (S11) for acquiring a transfer function indicating a relationship between the excitation force as an input and the strain response of each of the strain gauges 20, based on an output result from the force sensor 35 of the excitation force identification system 1, the excitation force identification system 1 including at least one strain body 10 provided between a rotating device 7 and a foundation 6, at least one strain gauge 20 provided on each of the strain bodies 10, an excitation device 30 for applying an excitation force to the rotating device 7 based on an input sine sweep signal 34, and a force sensor 35 for measuring the excitation force applied from the excitation device 30, and an output result from each of the strain gauges 20 when the excitation device 30 applies the excitation force;
and an excitation force identification process for identifying the force generated in the rotating device 7 during operation based on the output results from each of the strain gauges 20 when the rotating device 7 is operating and the transfer function acquired in the transfer function acquisition process.

According to the configuration (8) above, for the same reason as in (1) above, the force generated by the rotating device 7 during operation can be accurately determined even when the rotating device 7 operates at a low rotation speed.

1: Excitation force identification system 5, 5X, 5Y, 5Z: Point of action 6: Foundation 7: Rotation device 7a: Rotation shaft 7b: Housing 10, 10a, 10b, 10c: Strain generating body 20, 20a, 20b, 20c: Gauge 30: Excitation device 34: Sine sweep signal 35: Force sensor 40: Transfer function acquisition unit 50: Excitation force identification unit

Claims (8)

At least one strain body provided between the rotating device and the foundation;
At least one strain gauge provided on each of the strain bodies;
a vibration device for applying a vibration force to the rotating device based on an input sine sweep signal;
a force sensor for measuring the excitation force applied from the vibration device; and
a transfer function acquisition unit for acquiring a transfer function indicating a relationship between the excitation force as an input and a strain response of each of the strain gauges based on an output result from the force sensor and an output result from each of the strain gauges when the excitation device applies the excitation force;
and an excitation force identifying unit for identifying a force generated in the rotating device during operation based on output results from each of the strain gauges when the rotating device is operating and the transfer function acquired by the transfer function acquisition unit. the at least one strain gauge comprises a plurality of strain gauges;
The excitation force specifying system according to claim 1 , wherein the transfer function acquisition unit is configured to acquire a plurality of the transfer functions corresponding to the plurality of strain gauges, respectively. The excitation force identification system according to claim 2, wherein the at least one strain gauge includes two strain gauges each extending in a direction intersecting each other. The excitation force identification system according to any one of claims 1 to 3, wherein each of the strain gauges is provided radially outward from the housing of the rotating device in a plan view, with the rotation axis of the rotating device as a reference. The excitation force identification system according to any one of claims 1 to 4, wherein the transfer function acquisition unit is configured to acquire a plurality of the transfer functions for each of a plurality of points of action to which the excitation force is applied in the rotating device. the at least one strain gauge comprises a plurality of strain gauges;
the transfer function acquisition unit is configured to acquire a plurality of the transfer functions for each of the plurality of points of application to which the excitation force is applied in the rotation device,
The vibration force specifying system according to claim 5 , wherein the number of the strain gauges is the same as the number of the points of application. The excitation force identification system according to any one of claims 1 to 6, wherein the strain body is provided between the reciprocating compressor, which is the rotating device, and the foundation. A method for identifying an excitation force by an excitation force identifying system, comprising:
a transfer function acquisition step of acquiring a transfer function indicating a relationship between the excitation force as an input and a strain response of each of the strain gauges based on an output result from the force sensor of the excitation force specifying system, the excitation force specifying system including at least one strain body provided between a rotating device and a foundation, at least one strain gauge provided on each of the strain bodies, an excitation device for applying an excitation force to the rotating device based on an input sine sweep signal, and a force sensor for measuring the excitation force applied from the excitation device and an output result from each of the strain gauges when the excitation device applies the excitation force;
and an excitation force specifying step of specifying a force generated in the rotating device during operation based on output results from each of the strain gauges when the rotating device is operating and the transfer function acquired in the transfer function acquisition step.

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