JPS6271483A - Torque control type external vibrationproof type rotary compressor - Google Patents

Abstract

PURPOSE:To attain vibration damping and low noises extending over a wide revolution-number region by controlling the electromagnetic torque of an electrically operated element near a resonance point and in a low revolution region and damping vibrations by a vibration isolation effect by a vibrationproof material in a high revolution region. CONSTITUTION:A detecting signal 37 acquired by a gap sensor 34 is transmitted over a CPU 41 through an interface 40. A current value transmitted over an electrically operated element 2 for a compressor required for the variation of the speed of revolution after one turn to zero is arithmetically operated from speed variation at every moment at that time, and memorized previously to a RAM 42 up to a point of time when the data are needed. Data written to the RAM 42 are read by the CPU 41, and sent to a control section 44, and a chopper signal driving a base driver 45 is formed.

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention relates to a hermetic or semi-hermetic rotary compressor,
In particular, the present invention relates to a torque-controlled external vibration-isolating rotary compressor that achieves low vibration through electromagnetic torque control of the electric motor and an external vibration-isolating member.

[Background of the invention]

When looking at conventional compressors from the perspective of anti-vibration measures, they can be divided into internal anti-vibration types and external anti-vibration types.

FIG. 11 shows a reciprocating compressor as an example of an internal vibration-proof compressor. In such an internally vibration-isolated compressor, the compression element 72 or the electric element 71 (the first
In Figure 1, when fixing the compression element 72) to the storage case 70゛, it is attached via a vibration isolating material such as a spring, and after vibration isolation is performed here, the storage case 70 is attached to the base (not shown) with a supporting material. Generally, it is fixed via 74. Therefore, in the internal vibration isolation type, most of the vibration generated inside the compressor is absorbed by the internal vibration isolation material, and the excitation force transmitted from the storage case 70 to the base through the support material 74 is not so large.

On the other hand, in an external vibration-isolating compressor, the electric element and the compression element are fixed integrally with the storage case, and vibration isolation is performed only by the vibration-isolating support material that attaches the compressor to the base. FIGS. 12 and 13 are diagrams showing a rotary compressor as a conventional example of an external prevention photographing compressor. Here, the electric element 2 includes a stator 3 fixed to the case 1,
It mainly consists of a main shaft 6 supported by a main bearing 4 and an end bearing 5, and a rotor 8 fixed to this main shaft 6. , the cylinder block 12 interlocks with the main shaft 6.
The roller 16 is disposed within the compression working chamber 14 and defines a compression working chamber 14. Incidentally, reference numeral 17 denotes a vane which protrudes into the pressure working chamber 14 and is in contact with the surface of the roller 6, and is urged by a spring 19 and always in contact with the roller 16. Reference numeral 20 denotes a suction accumulator, and when the main shaft 6 rotates, refrigerant gas is sucked from the accumulator 20, pressurized to a predetermined pressure within the compression working chamber 14, and flows in the direction shown by the arrow in FIG. 16 to the outside of the case 1. It is designed to be discharged.

In this type of compressor, the electric element 2 outputs a nearly constant torque over time, whereas the gas absorption torque within the compression element 10 fluctuates greatly during one rotation of the main shaft 6. During machine operation, the torque of electric element 2 and compression element 1
The torque difference between the zero absorption torques causes rotational speed fluctuations in the rotating system of the compressor and rotational vibrations in the stationary system.

In such an external vibration-isolating type rotary compressor, a vibration-isolating member 22 is interposed to provide vibration isolation in order to prevent the excitation force caused by the vibration of the compressor from being transmitted to the base (not shown). I have to. However, unlike the internal vibration isolation type, the compressor itself vibrates together with the vibration isolation member 22 due to the excitation force of the compressor, and this vibration is transmitted to the piping system (not shown) through the case l. A problem arises.

This is particularly effective when the compressor is operated at a constant rotational speed, but when trying to control the rotational speed of the electric element 10, that is, the electric motor over a wide range using an inverter,
The vibration isolation effect is extremely poor near the common application point, especially in the low rotation range, and this vibration accelerates Case 1 and the pipes, producing noise. If this condition continues for a long time, serious accidents such as pipes breaking can occur. There were problems such as the possibility of this occurring.

Note that one example of something similar to the present invention is Japanese Patent Application Laid-Open No. 60-6028.
There is Publication No. 6.

[Purpose of the invention]

An object of the present invention is to provide an external vibration-isolated compressor with low vibration and low noise.

[Summary of the Invention] A system in which a compressor, which is an excitation source, is externally vibration-isolated by a vibration isolating member is considered to be a case of forced vibration with one degree of freedom. At this time, the transmission rate (vibration transmission rate) of the force by which the excitation force by the compressor is transmitted to the base through the vibration isolation support system becomes a problem. Figure 14 shows the harmonic excitation force ΔTsi as an excitation source.
nωt (ΔT Residual torque of two motorized elements and compression element, ω:
FIG. 3 is a diagram showing the vibration transmissibility λ when the same wave number of excitation is acting on a vibration system having a compressor mass m, a spring constant 1, and a viscous damping coefficient C.

As shown in the figure, although it is effective in increasing the damping coefficient C, it is in the region of ->5, that is, it is high, and is not effective as a vibration isolation method. Normal rotating machinery is generally operated in a high rotation region (high vibration region) above the resonance point, so the original purpose of vibration isolation is rather to reduce the vibration transmissibility in this region. There is a particular thing.

However, at the same time, when operating a normal rotating machine, it is necessary to provide a certain degree of damping to avoid danger when passing through a resonance point during acceleration or deceleration.

In order to solve these problems, we use a spring that has a damping coefficient that decreases in proportion to the vibration frequency, such as anti-vibration rubber. ), methods to remove the negative effects of viscous damping in high frequency ranges were common methods.

However, even if these are used, the vibration suppression effect near the resonance point is not sufficient, and in the low rotation region below the resonance point, the transmissibility λ will not become smaller than 1 regardless of the value of the damping coefficient C. , the excitation force is directly transmitted to the base and there is no vibration isolation effect.

The present invention has been made in view of the above considerations.

In other words, when it is desired to use an inverter to operate the compressor over a wide range of operating ranges, from the low speed range below the resonance point to the high speed range above it, external vibration-isolated compressors need to operate the compressor in the low speed range and near the resonance point. By controlling the electromagnetic torque of the electric element so as to balance it with the absorption torque of the compression element in the area, the rotational speed fluctuation of the rotor-1 main shaft is reduced,
Suppresses rotational direction vibration on the case side and reduces the excitation force itself.

On the other hand, in the high rotation range, effective vibration isolation is achieved by employing a vibration isolating material that has a small damping coefficient and can minimize the vibration transmission rate in the high rotation range. In this way, external vibration-isolated compressors use a combination of torque control and vibration-isolating materials that are optimal for vibration isolation in high-speed ranges, resulting in low vibration and noise throughout the entire operating range of the compressor. can be achieved.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be described based on the drawings. FIG. 1 is a diagram showing a first embodiment of the present invention, and a compressor 30 according to the first embodiment is shown in FIG. 14.

Since the configuration is almost the same as that of the conventional compressor shown in FIG. 15, only the different parts will be explained, and the same parts will be given the same reference numerals and the explanation thereof will be omitted.

In FIG. 1, one end of the rotor main shaft 6 that directly connects the electric element 2 and the compression element 10 is extended, and a gear 32, which is a rotation detection member, is fixed, and the gear 32 and the main shaft 6 rotate together. It looks like this.

A gap sensor 34 is fixed to the case 1.
The tooth row of the gear is detected and a rotation pulse signal corresponding to the rotation speed of the main shaft 6 is output.

FIG. 2 shows the rotation pulse signal detected by the gap sensor 34. Here, a reference line 35 indicating the center output level of the detection signal 37 is considered, and after the signal crosses this reference line 35, it returns to the reference line 35. By determining the time t1 until the line 35 is crossed, the rotational speed of the main shaft 6 at each point in time can be obtained from the number of teeth of the gear 32. Fig. 3 shows the fluctuation state of the rotational speed of the main shaft 6 based on the rotational speed signal shown in Fig. 2. Reference numeral 36 indicates the average rotational speed of the main shaft 6.

Area A indicates advance, and area B indicates lag.

Note that the average rotation speed can be determined by the average time.

Information regarding the rotational speed fluctuation value obtained in this way is sent to a control circuit 38 shown in FIG. 4 and processed. That is, the detection signal 37 obtained by the gap sensor 34 is converted into a digital signal related to rotational speed fluctuation by the waveform shaping preamplifier 39, and is sent to C'P via the interface 40.
Sent to U41.

Here, the current value to be applied to the electric element 2 of the compressor necessary to zero the rotational speed fluctuation after one rotation is calculated from the momentary speed fluctuation amount, and the data is stored in the RAM 42 until it is needed. I'll let you.

Next, the data written in the RAM 42 is read out by the CPU 41 and sent to the control section 44 to form a chopper signal for driving the pace driver 45.

At the same time, the CPU 41 controls the interface 40 so that the inverter 46 generates the required current value at each rotation angle.
A timing signal is sent to the pace driver 45 via the pace driver 45.

The inverter 46 driven by the pace driver 45 controls the rotational speed of the main shaft 6 by increasing or decreasing the amount of current applied to the electric element 2 so that the rotational speed fluctuation of the main shaft 1116 becomes zero at each rotation angle. is constantly controlled so that the fluctuation always stays within a certain tolerance value. Moreover, these series of control loops are written in the ROM 43.

Next, when performing control, there are two cases in which the amount of current is calculated using only the value one rotation before the current rotation speed fluctuation information.
A possible method is to stock information up to several rotations before the current one, perform statistical processing, and then determine the amount of current based on the statistics. In the latter method, when the fluctuations are periodic, noise components due to accidental fluctuations are cut out, making it possible to perform more reliable control. As a statistical processing method, the first method that can be considered is to use the average value obtained by simply averaging the rotation speed fluctuations for each rotation angle up to the past few rotations.
In this case, it is effective to perform smoothing using a low-pass filter in order to cut high-frequency noise components. It is also effective to set a threshold value so as not to pick up temporarily excessive fluctuations due to external factors, and to perform averaging processing while ignoring larger fluctuations. Another effective method for statistical processing is the moving average model method. This is obtained by taking a weighted moving average of rotational speed fluctuation data (input data) given in time series. Expressed by Equation (3), if the th input data time series Xt+ (time width T), output data (statistics) y2, and coefficient parameter ak, then the following is obtained.Such statistical processing is as shown in Figure 5. is obtained by using a linear acyclic digital filter. This applies adder 479 multiplier 49 . The unit delay element 48 is composed of three types of elements.

In this way, in this embodiment, when a DC motor is used as an electric element and is driven by an inverter, a control circuit as shown in Fig. 4 is used to quickly change the power source so as to minimize rotational speed fluctuations. As a result, vibrations in the rotational direction of the fixed system can also be suppressed.・Also, it is worth noting that there is no effective method for understanding torque fluctuations in a rotating system other than using rotational speed fluctuation information. In addition to this, the following sensorless system that does not require a sensor inside the compressor can be considered. That is, when a current is passed through each conductor of the DC ft11jJ machine, a back electromotive force is induced in the direction opposite to the direction of the current according to Fleming's law, and its magnitude is proportional to the rotational speed of the motor. Therefore, rotational speed fluctuation information can also be obtained by detecting current changes due to changes in back electromotive force caused by rotational speed fluctuations.

Next, FIGS. 6@ and 7 show an embodiment in which vibration in the rotational direction of the fixed system is directly measured and controlled so as to be suppressed.

FIG. 6 shows how the mounting jig 52 is attached to the case 1 of the compressor.
Support member 5 with this mounting jig 52 installed on base 54
6, the compressor is placed horizontally, and a load detector 58 is interposed between the support member 56 and the mounting jig 52. Note that numerals 50 and 51 indicate a suction pipe and a discharge pipe, respectively.

FIG. 7 shows an embodiment in which a mounting jig 52 attached to the compressor case 1 is supported by a support member 57 fixed to a base 54, and a strain detector 6o is installed on the support member 57.

When the compressor is operated, rotational vibrations are induced in the compressor case 1, and each detector 58, 60 receives a response signal (load change or strain change) as shown in FIG. The response signal is the absorption torque of the compression element (first
(see Figure 3), and the control circuit described above (see Figure 4) adjusts the voltage so that these response signals become zero.
Compressor vibration can be suppressed by controlling the current values of the elements. Although the compressor is shown in a horizontal position in FIGS. 6 and 7, it is not limited to horizontal installation, and vertical or diagonal installation is also possible.

Furthermore, the present invention aims to reduce the rotational vibration of the rotating system by controlling the electromagnetic torque of the electric element in accordance with the load, and the load does not have to be a compressor, but rather It can be applied to all rotating systems.

In addition, in this embodiment, the pressure fl! ! ! If torque control is always executed for 1, only the control stability will be a problem, but according to the method of the embodiment in which data from one or more previous rotations is fed back during the current rotation, once the control is After completion and the phase is locked (that is, both torque curves are equal within a controllable range), the state becomes extremely stable.

The inventors have experimentally confirmed that the control does not become unstable even when disturbances are applied.

On the other hand, when torque control is performed only within a certain rotation speed range of the compressor and not at other rotation speeds (
For example, torque control is performed only near and below the resonance point where rotational vibration is greatest. ), the problem is the establishment time from when the control is started until it is completed and the phase is locked and a stable state is achieved.

In response to this, 1, for example, the RAM 42 of the control circuit 38 is further expanded, and data of the current value to be applied to the electric element necessary to make the rotational speed fluctuation zero for each rotational speed and operating conditions such as discharge and suction pressure is generated. One effective method is to grasp and memorize (one rotation pattern) through learning control from past experience.

FIG. 9 shows a case where the compressor is placed horizontally and supported at four points by vibration isolating rubber 62 via a mounting jig 63. FIG. 10 shows the results of an experiment to determine the magnitude of rotational direction vibration on the chamber surface of the compressor 30 with a vibration pickup 62 attached.

In the case where 1-lux control is not performed as shown by the solid line in the figure,
The resonance point of the vibration system consisting of the compressor 30 and vibration isolating rubber is N=
The figure shows that it is around 900 rpm, and it can be seen that the effect of torque control shown by the broken line in the figure is greatest around this point and below. On the right side of the resonance point, the excitation force of the rotational vibration is mainly consumed by inertial force, so the absolute value of the vibration displacement itself becomes small, so the difference in influence due to the presence or absence of torque control becomes relatively small. Therefore, it is also possible to block vibrations by the vibration-isolating effect of the vibration-isolating member in the region of high rotational speed on the right side of the resonance point, and to perform torque control before and after the resonance point and below the resonance point where vibration displacement is large. What is important at this time is that the magnitude of the peak at the resonance point is no longer a problem due to the torque control effect, so the damping coefficient C of the vibration isolating member can be made relatively smaller than when no torque control is performed. As mentioned above, the frequency of rotational vibration ω is the natural frequency of the system. In the region where the damping coefficient is more than 5 times larger, the vibration transmissibility λ can be reduced by reducing the damping coefficient (see Fig. 12). Select a small vibration isolating material, and place it around the resonance point (ω
In the low rotation range from ω0), it is possible to make maximum use of the excitation force reduction effect by torque control to achieve low vibration in the entire operating rotation speed range of the compressor.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to reduce vibration by controlling the electromagnetic torque of the electric element near the resonance point and in the low rotation range, and by using the vibration isolation effect of the vibration isolating material in the high rotation range. It becomes possible to control the operation of the rotary compressor over a wide rotation speed range.

[Brief Description of the Drawings] Figure 1 is a longitudinal cross-sectional view of the first embodiment of the present invention, Figure 2 is a diagram showing the detection signal output from the gap sensor, and Figure 3 is the rotational speed fluctuation of the rotating main shaft. FIG. 4 is a diagram showing the state, FIG. 4 is a diagram of a control circuit for achieving this control, FIG. 5 is a circuit diagram for performing moving average processing on speed detection data, and FIG. 6 is a diagram of a second embodiment of the present invention. 7 is a front view of the main part of 1.
8 is a front view of main parts of the embodiment of 2. Diagram showing response signals of the load detector and strain detector used in the third embodiment, No. 9
The figure is a schematic diagram showing a fourth embodiment in which the compressor is supported at four points on a base with vibration-proof rubber, and Figure 10 is a diagram showing experimental results of vibration displacement of the chamber surface with and without torque control. , Fig. 11 is a longitudinal sectional view of a reciprocating compressor shown as 1@ of an internal vibration-isolated compressor, Fig. 12 is a longitudinal sectional view of a conventional hermetic rotary compressor, and Fig. 13 is shown in Fig. 12. Line X-
FIG. 14, which is a sectional view taken along the line x, shows the vibration transmission rate when the excitation force is transmitted to the base through the vibration isolating member in the external vibration isolating expansion compressor. 1... Case, 2... Electric element, 6... Main shaft, 8
... Rotor, 10... Compression element, 14... Compression working chamber, 16... Roller, 22... Vibration isolating member, 30...
...Compressor, 32...Gear, 34...Gap sensor, 38...Control circuit.

Claims (1)

[Claims] 1. In a hermetic or semi-hermetic rotary compressor that is composed of a compression element, an electric element that drives the compression element, and a case that houses them, the vibration isolation performance of the vibration isolation member is reduced. The electromagnetic torque of the electric element is adjusted during one rotation so that the rotational speed fluctuation during one rotation of the rotor main shaft of the compression element and electric element becomes small near the resonance point and in the low rotation region, and the rotational direction vibration of the storage case is suppressed. 1. A torque-controlled external vibration-isolated rotary compressor, characterized by having a torque control device that divides and controls the compressor. 2. In claim 1, the vibration isolating member that supports the compressor on the base is configured such that the vibration transmissibility is small in the high rotation range where the excitation frequency is higher than the resonance point, that is, the compression A torque-controlled external vibration-isolating rotary compressor, characterized in that the damping coefficient of the vibration-isolating member is set small to absorb the excitation force of the machine.