JPH0436000B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a hermetic compressor, and more particularly to a torque-controlled hermetic compressor that achieves low vibration by controlling the electromagnetic torque of an electric element.

[Prior art]

An example of a conventional hermetic compressor is shown in Figure 16 and Figure 1.
It is shown in Figure 7. These figures show a rotary compressor in which an electric element 2 and a compression element 10 are housed in a case 1. The electric element 2 mainly includes a stator 3 fixed to a case 1, a main shaft 6 supported by a main bearing 4 and an end bearing 5, and a rotor 8 fixed to the main shaft 6. Element 1
0 is cylinder block 1 fixed to case 1
2, and a roller 16 which is interlocked with the main shaft 6, is disposed within the cylinder block 12, and defines a compression working chamber 14. Reference numeral 17 denotes a vane that protrudes into the pressure working chamber 14 and comes into contact with the surface of the roller 16, and is urged by a spring 19 so as to be in constant contact with the roller 16. Reference numeral 20 denotes a suction accumulator, and when the main shaft 6 rotates, refrigerant gas is sucked from this 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 starting to be expelled.

[Problem that the invention seeks to solve]

In this type of compressor, while the electric element 2 outputs a nearly constant torque over time, the gas absorption torque within the compression element 10 fluctuates greatly during one rotation of the main shaft 6. During operation of the compressor, the torque difference between the torque of the electric element 2 and the absorption torque of the compression element 10 acts as a source of vibration, causing large rotational vibrations throughout the compressor. In addition, a vibration isolating member as shown by reference numeral 22 in FIG. 16 is attached to the base (not shown) and the case 1.
Technologies interposed between the
There is also 187635. However, although this conventional technology is effective when the compressor is operated at a constant rotational speed, it is difficult to control the rotational speed of the electric element 10, that is, the electric motor over a wide range, especially at low rotational speeds. The vibration isolation effect is extremely poor in the area, and this vibration excites the case 1 and piping, causing noise. If this condition continues for a long time, there is a risk of serious accidents such as pipes breaking. There was a problem.

An object of the present invention is to provide a hermetic compressor free from vibration by eliminating the torque difference between the absorption torque of the compression element and the electromagnetic torque of the electric element.

[Means for solving problems]

In order to achieve the above object, the present invention provides a hermetic compressor in which a compression element and an electric element for driving the compression element are housed in a closed container, in which the compression element is rotated at a corresponding rotation angle of the main shaft of the compression element. means for detecting the torque difference between the absorption torque and the electric torque of the electric element; a drive device that drives the variable element with variable rotational speed; The present invention proposes a torque-controlled hermetic compressor equipped with an output torque control device that controls the current supplied to the electric element using a step-like command signal to reduce rotational speed fluctuations during one revolution of the main shaft. .

Specifically, the means for detecting the torque difference detects the torque difference based on fluctuations in the rotational speed of the main shaft,
The torque control device controls the electromagnetic torque of the electric element so that fluctuations in the rotational speed of the main shaft approach zero.

The means for detecting the torque difference may detect the torque difference based on rotational acceleration generated in a non-rotating portion of the compression element or the electric element. In that case, the torque control device controls the electromagnetic torque of the electric element so that the rotational speed approaches zero.

In either case, the torque control device
It is possible to incorporate a plurality of electromagnetic torque command output patterns each having one cycle of rotation.

The output pattern of the electromagnetic torque can be a one-component pattern of first to nth order components obtained by Fourier expansion of the absorption torque of the compression element, or a composite pattern of a plurality of components.

[Effect]

According to the present invention, the torque control device controls the electromagnetic torque of the electric element to be equal to the absorption torque of the compression element, so the torque difference between the absorption torque and the electromagnetic torque disappears or becomes small. Rotational vibration of the compressor is prevented.

〔Example〕

Next, embodiments 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 this embodiment has almost the same configuration as the conventional compressor shown in FIGS. 16 and 17. Therefore, only the different parts will be explained,
Identical parts will be given the same reference numerals and their explanation will be omitted.

In FIG. 1, the main shaft 6 constituting the compression element 2
A gear 32, which is a rotation detection member, is fixed to the upper end of the gear 32, and the gear 32 and the main shaft 6 rotate together. An electromagnetic pickup 34 having its own magnetic field is fixed to the case 1, and outputs a signal corresponding to the rotational speed of the main shaft 6, as shown in FIG. That is, the symbol 3 in Figure 2
Considering the reference line indicated by 5 (the reference line connecting the center output level of the signal) and finding the time t from when the signal crosses this reference line 35 until it crosses the reference line 35 again, the number of teeth of the gear 32 can be determined. The momentary rotational speed of the main shaft 6 can be obtained from . FIG. 3 shows the fluctuation state of the rotational speed of the main shaft 6 based on the rotational speed signal shown in FIG. Each shows a delay. Note that the average rotational speed is determined by the average time t _i
(=1/n _o 〓 ⁱ⁼¹ t _i ) and the gear m of the gear 32, and the lead/lag amount ω can be found from ω∝ta (t _i /t _a −1).

FIG. 4 is a diagram showing the relationship between the absorption torque of the compression element 10 and time. The phase coincides with the rotational speed fluctuation of the main shaft 6 shown in FIG. 3, and as the absorption torque increases, the rotational speed of the main shaft 6 increases. There is a correlation between the absorption torque of the compression element and the rotation speed of the main shaft 6, such that as the absorption torque decreases, the rotation speed increases.

The main shaft 6 detected by this electromagnetic pickup 34
As shown in FIG. 5, the rotational speed of
This is expressed as a rotational speed fluctuation of the main shaft 6 as shown in the figure, and is output to the control section 40. In response to this, the control unit 40 controls the rotational speed of the main shaft so that the change in rotational speed becomes zero.
The electromagnetic torque of the electric element is controlled via a power supply frequency variable device 42. A so-called inverter power supply is commonly used to change the rotational speed of the compressor, but since a DC motor can be used as the electric element, it is easy to control the power supply or current, and the speed of the main shaft 6 can be easily controlled. I can do it.

In this way, this embodiment has a control system that feeds back the rotational speed of the main shaft 6 as shown in FIG. Rotational speed fluctuations are suppressed and vibration generation is suppressed.

FIG. 6 and FIG. 7 are the second and third embodiments of the present invention, respectively.
This shows a third example.

FIG. 6 shows that a mounting jig 52 is attached to the case 1 of the compressor, this mounting jig 52 is supported by a support member 56 installed on a base 54, the compressor is placed horizontally, and the support member 56 is The main part of a second embodiment in which a load detector 58 is interposed between the mounting jig 52 and the mounting jig 52 is shown. Note that numerals 44 and 46 indicate a suction pipe and a discharge pipe, respectively.

FIG. 7 shows a main part of a third embodiment in which a mounting jig 52 attached to a compressor case 1 is supported by a support member 57 fixed to a base 54, and a strain detector 60 is installed on the support member 57. It shows.

When the compressor is operated, rotational vibrations are induced in the compressor vessel 1, and the respective detectors 58 and 60 generate response signals as shown in FIG. In the example, the response signal is subject to a change in strain), but it has become clear from the inventors' experimental results that these response signals correspond to the absorption torque of the compression element (see Fig. 4), and the first A feedback control device similar to that shown in the embodiment (fifth
In other words, by operating the control section 40 and the power supply frequency variable device 42 so that the response signal shown in FIG. Machine vibration can be suppressed. Although FIG. 7 shows the compressor placed horizontally, the compressor is not limited to being placed horizontally, and may be placed vertically or diagonally.

Furthermore, the present invention aims to reduce the rotational vibration of a rotating system by controlling the electromagnetic torque of an electric element according to the load. It is applicable to all. Furthermore, when performing torque control, it is not necessary to match the load torque and electromagnetic torque as long as there is an allowable value for the amount of rotational vibration reduction; vibration can be reduced by simply controlling by approximating the pattern per cycle. It is effective in doing so.

FIG. 9 is a diagram showing a fourth embodiment of the present invention.

In this figure, reference numeral 62 denotes a pressure sensor for detecting changes in the pressure of gas within the compression chamber, and is provided near the discharge port of the cylinder. Since the other parts are the same as those of the conventional compressor (see FIGS. 16 and 17), the same reference numerals are given and the explanation thereof will be omitted. Note that the reference numeral 64 is a pressure communication hole extending from the inside of the pressure working chamber 14 to the discharge port. With this pressure sensor 62, pressure fluctuations in the compression working chamber as shown in FIG. 10 can be obtained. The output of this pressure sensor 62 is connected to a calculator 38 of the torque control device shown in FIG. 11, and is calculated by the calculator 38 so that the glass absorption torque changes as shown in FIG. ing. A control signal is sent to the control unit 40 so that the electromagnetic torque matching the absorption torque calculated by the calculator 38 is output from the electric element. The control unit 40 is a power supply frequency variable device 42
In other words, the current or voltage supplied to the electric element is controlled, and the electromagnetic torque of the electric element matches the absorption torque of the compression element to suppress rotational vibration. suppress. Further, if the electric frequency variable device 42 cannot change the output power of the electric element, it is necessary to provide a separate power changing device.

Note that the computing unit 38 receives a signal from the pressure sensor 62 and outputs a signal equal to the absorption torque of the compression element, but even if it is not necessarily equal to the absorption torque, it is within a range sufficient to suppress rotational vibration. Any signal that outputs the torque of It may be something like that. Figure 13 shows the Fourier expansion of the absorption torque when the compressor is operated under certain pressure conditions, from the first to the third order components, where curve A is the first order component and curve B is the second order component. The next-order component and curve C indicate the third-order component, respectively. Note that in FIG. 13, the level serving as a positive/negative reference has the magnitude of the O-order component. Fig. 14 is a diagram showing the torque difference between the absorption torque of the compression element and the electromagnetic torque of the electric element, and curve a shows the torque difference between the absorption torque and the electromagnetic torque when the electromagnetic torque of the electric element is not controlled. There is. Curve b shows the torque difference between the absorption torque and the absorbed torque when the first-order component shown by reference numeral A in Fig. 13 is output as electromagnetic torque.
Curve c shows the torque difference from the absorbed torque when the torque is output as an electromagnetic torque which is a combination of the primary and secondary components shown by reference numerals A and B in FIG. 13, respectively. As can be seen from Fig. 14, when no torque control of the electric element is performed (curve a)
Compared to the case where torque control is performed (curves b and c), the residual torque acting on the rotation system of the compressor is smaller, so when a torque pattern based only on the first-order component is output from the electric element. (Curve b) also has the effect of reducing rotational vibration. It is more preferable to synthesize the first to nth order components, but in practice, a combined torque pattern of about the first to second order components is sufficient. Also these n
It is also possible to arbitrarily select a plurality of torque patterns (n=1 to n) up to the next component.

In addition, the control unit 40 controls the power supply frequency variable device 42.
When controlling the current or voltage supplied to the compressor by
It is desirable to control the output of the electromagnetic torque of the electric element in a stepwise manner by outputting it for each rotation angle equally divided by the product of the number of poles P and the number S of slots of the electric element. For example, when a two-pole electric element is used and the number of slots per pole is 6, the rotation angle is divided into 12 equal parts per rotation of the main shaft, that is, every π/6, as shown in Fig. 15. Torque pattern control is performed as follows. This Fig. 15 shows the result of step torque control for the case shown by reference numeral b in Fig. 14 (combined torque pattern of primary and secondary components). It is extremely practical due to the configuration of the electric elements applied to the machine. Further, in order to control the rotation speed of the compressor, it is desirable to use a DC motor as the electric element, and it is easy to implement a method of controlling the electric current and controlling the electromagnetic torque.

In addition, in the fourth embodiment, the pressure change of the gas in the compression chamber is used as the detection signal, but
It is also possible to use a pressure change between a high pressure section and a low pressure section in a refrigeration cycle (not shown) as a detection signal. In this case, the pressures in the high pressure section and the low pressure section approximately correspond to the pressures indicated by Pd and Ps in FIG. 10, respectively. However, in this case, a separate means for receiving a signal indicating one cycle of the rotating system is required.

Furthermore, instead of changing the pressure of the gas in the compression working chamber, the main shaft 6 shown in the first to third embodiments
It is also possible to calculate the absorption torque pattern of the compression element from the rotational speed fluctuations of the compressor and changes in the load and strain transmitted to the non-rotating system of the compressor, and use these as a detection signal.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, vibrations of a compressor can be significantly reduced, and even in a compressor whose rotational speed can be varied over a wide range, vibrations can be reduced.

[Brief explanation of drawings]

FIG. 1 is a longitudinal cross-sectional view of the first embodiment of the present invention, FIG. 2 is a diagram showing a detection signal output by an electromagnetic pickup, and FIG. 3 is a diagram showing the rotational speed fluctuation state of the main shaft of the compression element. FIG. 4 is a diagram showing absorption torque fluctuations in the compression chamber, FIG. 5 is a schematic diagram of the torque control device, FIG. 6 is a front view of main parts of the second embodiment of the present invention, and FIG. 7 is a diagram of the present invention. FIG. 8 is a diagram showing the response signals of the load detector and strain detector used in the second and third embodiments, and FIG. 9 is a front view of the main parts of the third embodiment of the present invention. 10 is a diagram showing the pressure fluctuations in the compression working chamber of the compression element, FIG. 11 is a schematic diagram of the torque control device, and FIG. 12 is the pressure shown in FIG. 10. Figure 13 is a diagram showing the gas absorption torque fluctuation of the compression element corresponding to the fluctuation. Figure 13 is a diagram showing the absorption torque of the compression element independently from the first to third components after Fourier expansion. A diagram showing the torque difference between the absorption torque and the electromagnetic torque when the electromagnetic torque of the electric element is controlled, FIG. 15 is a diagram showing the torque difference between the absorption torque and the electromagnetic torque when the step torque is controlled at π/6 intervals, FIG. 16 is a longitudinal sectional view of a conventional hermetic compressor, and FIG. 17 is a sectional view taken along line XX shown in FIG. 16. 1...Container, 2...Electric element, 6...Main shaft, 1
0... Compression element, 14... Compression working chamber, 16...
Roller, 22... Vibration isolation member, 30... Compressor, 3
2...Gear, 34...Electromagnetic pick-up, 38...
... Arithmetic unit, 40 ... Control unit, 42 ... Power frequency variable device, 52 ... Mounting jig, 58 ... Load detector, 60 ... Strain detector, 62 ... Pressure sensor.

Claims (1)

[Claims] 1. In a hermetic compressor in which a compression element and an electric element for driving the compression element are housed in a hermetic container, the absorption torque of the compression element at a corresponding rotation angle of the main shaft of the compression element; means for detecting a torque difference between the electromagnetic torque of the electric element; a drive device that drives the electric element with variable rotational speed; one rotation of the main shaft is one period, the period is divided into a plurality of periods, and for each division, the 1. A torque-controlled hermetic compressor, comprising: a torque control device that controls current supplied to an electric element using a step-like command signal and outputs the current so as to reduce fluctuations in rotational speed during one rotation of a main shaft. 2. In claim 1, the means for detecting the torque difference is means for detecting the torque difference based on a variation in the rotational speed of the main shaft, and the torque control device is configured to detect the torque difference based on a variation in the rotational speed of the main shaft. 1. A torque-controlled hermetic compressor, characterized in that the torque-controlled hermetic compressor is a means for controlling the electromagnetic torque of the electric element so that fluctuations in the electric component approach zero. 3. In claim 1, the means for detecting the torque difference is means for detecting the torque difference based on a rotational acceleration occurring in a non-rotating portion of the compression element or the electric element, and the torque control A torque-controlled hermetic compressor, characterized in that the device is means for controlling the electromagnetic torque of the electric element so that the rotational direction acceleration approaches zero. 4. In any one of claims 1 to 3, the torque control device converts one rotation of the main shaft into one revolution.
A torque-controlled hermetic compressor, characterized in that it has a plurality of command output patterns of the electromagnetic torque as a cycle. 5. In claim 4, the output pattern of the electromagnetic torque is a first-order component ~n obtained by Fourier expansion of the absorption torque of the compression element.
A torque-controlled hermetic compressor characterized by a one-component pattern of the following components or a composite pattern of multiple components.