JP2003003958A - Hermetic electric compressor and refrigerating device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a hermetic electric compressor in which a coolant mainly comprising R600a which is a hydrocarbon coolant of small warming coefficient is used, vibration is reduced, and noise is decreased, and provide a refrigerating device in which noise is decreased, and reliability is high. SOLUTION: This reciprocating hermetic electric compressor of inverter- driven type uses the coolant comprising as a main component the hydrocarbon coolant mainly comprising R600a, and is driven with a plurality of operation frequencies including a revolution speed less than a commercial power supply frequency. In this hermetic electric compressor, a compression element is built at an approximately upper part of an electric element, and is elastically supported by a closed container at a lower part of the stator via a stator. Accordingly, the hermetic electric compressor in which the vibration is reduced and the noise is decreased is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hermetic compressor used in electric refrigerators, air conditioners, vending machines and the like.

[0002]

2. Description of the Related Art In recent years, demands for the global environment have been increasing more and more, and movements such as energy saving and regulation of gas with high greenhouse effect have been accelerated.

The prior art includes Japanese Patent Laid-Open Publication No. Hei 11
No. -1079331.

Hereinafter, the above-mentioned conventional hermetic electric compressor will be described with reference to the drawings. In the following description, the relationship between the upper and lower sides is based on the state in which the hermetic electric compressor is installed in a regular posture.

FIG. 4 is a cross-sectional view of a conventional hermetic electric compressor, in which 1 is a hermetic container for storing refrigerating machine oil 2. An electric element 5 is composed of a stator 3 and a rotor 4 containing a permanent magnet. 6 is a compression element, which is constructed below the electric element 5,
It is driven by the electric element 5 and both are housed in the closed container 1. Further, this hermetic electric compressor is R134a which is a typical HFC refrigerant having an ozone depletion potential of zero.
Is designed to compress.

Details of the compression element 6 will be described below.

A crankshaft 10 has a main shaft portion 11 into which the rotor 4 is press-fitted and fixed, and an eccentric portion 12 formed eccentrically with respect to the main shaft portion 11. Reference numeral 20 denotes a cylinder block, which has a substantially cylindrical compression chamber 22 and a bearing portion 23 that pivotally supports the main shaft portion 11, and is formed below the electric element. A piston 30 is inserted into the compression chamber 22 and is connected to the eccentric portion 12 by a connecting means 31. 33 is a balance weight in which iron plates are laminated and is fixed to the rotor 4. Reference numeral 35 is a valve plate that seals the end surface of the compression chamber 22, and 36 is a head that forms a high-pressure chamber and is fixed to the valve plate 35 on the side opposite to the compression chamber 22. A suction tube 39 is fixed to the closed container 1 and is connected to the low pressure side (not shown) of the refrigeration cycle to guide a refrigerant gas (not shown) into the closed container 1. A suction muffler 40 forms a sound deadening space 42. A suspension spring 50 is fitted between a snubb bar 52 fixed to the closed container 1 and a snubb bar portion 53 formed on the cylinder block 20, and elastically supports the compression element 6. An inverter device 60 is connected to the stator 3. Reference numeral 61 is a control circuit for controlling the inverter device 60, and 62 is a commercial power source connected to the control circuit 61 and the inverter device 61.

Generally, the power consumption of a compressor becomes smaller as the operating frequency becomes lower, and on the other hand, the refrigerating capacity corresponding to the load is also required at the same time. A plurality of output frequencies are arbitrarily set up to a level exceeding the frequency of the commercial power supply.

Next, a series of operations in the above configuration will be described.

Electric power supplied from the commercial power supply 62 is supplied to the electric element 5 via the control circuit 61 and the inverter 60, and rotates the rotor 4 of the electric element 5 at an arbitrary rotation speed. The rotor 4 rotates the crankshaft 10, and the eccentric movement of the eccentric portion 12 causes the piston 30 to move through the connecting means 31.
When the piston 30 is driven, the piston 30 reciprocates in the compression chamber 22, and the refrigerant gas introduced into the closed container 1 through the suction tube 39 is sucked from the suction muffler 40 and continuously compressed in the compression chamber 22. It

At this time, the vibration generated by the reciprocating motion of the piston 30 is largely canceled by the balance weight 33, but some vibration remains. The residual vibration thus vibrates the cylinder block 20 as its reaction, and this vibration is further damped by the suspension spring 50. The vibration of the hermetic electric compressor generated at this time has a larger amplitude as the rotation speed of the electric element is lower, but is at a level of about 32 μm, which is below 40 μm which is practically no problem at an operating frequency near 27 Hz. It was

[0012]

The hermetic electric compressor described above has a general structure which has already been put into practical use, but there is still room for improvement from the viewpoint of the global environment.

That is, the hermetic electric compressor of the prior art is
It is designed to compress R134a, which is a typical HFC refrigerant with an ozone depletion potential of zero.
The HFC-based refrigerant containing 34a has a high global warming potential, and has been determined to be regulated eventually. Instead of this, hydrocarbon refrigerants that have already been put to practical use in Europe and have a zero ozone depletion potential and a small global warming potential, specifically R60
0a is considered to be a powerful alternative refrigerant in Japan. However, R600a is
Since the refrigerating capacity per suction volume of the compressor is only about half, in order to obtain the refrigerating capacity equivalent to that of R134a, it is necessary to increase the displacement volume by the piston to nearly twice as large as that of R134a.

Usually, in order to increase the displacement volume (hereinafter referred to as the cylinder volume), the diameter of the compression chamber, that is, the outer diameter of the piston, or the eccentricity of the crankshaft, or both of them, is increased. Generally used together, increasing the outer diameter of the piston increases the mass of the piston, and increasing the eccentricity of the crankshaft increases the reciprocating acceleration of the piston. Therefore, when such a method is adopted, the vibration energy increases due to the reciprocating movement of the piston. Particularly, when the cylinder volume is expanded to nearly double, this vibration energy becomes very large.
On the other hand, the amplitude of the vibration of the compressor generated by this vibration energy increases as the rotation speed of the electric element decreases, because of the relationship between the inertial mass of the compression element and the electric element and the vibration energy. At low speed operation using an inverter device, specifically, at a rotation frequency around 27 Hz, vibration increases to a level of about 65 μm. At such an amplitude level, the noise generated by the compressor and the refrigeration system is increased due to this vibration, and the piping of the refrigeration system is fatigue-damaged by the vibration and breaks, causing the refrigerant to leak. There is a problem that it will end.

The present invention solves these problems and provides a hermetic electric compressor that uses a refrigerant mainly composed of R600a, and that has small vibration and low noise, and has low noise and reliability. It is an object of the present invention to provide a refrigeration system having a high price.

[0016]

The invention according to claim 1 of the present invention uses a refrigerant containing a hydrocarbon refrigerant mainly containing R600a as a main component, and a plurality of rotation speeds below the frequency of a commercial power source. An inverter-driven reciprocating hermetic electric compressor driven at an operating frequency, wherein the compression element is constructed substantially above the electric element, and the compression element passes through the stator, Since it is elastically supported from the closed container below, it has the effect of suppressing vibration during compression to a small level.

The invention according to claim 2 of the present invention is a refrigerating apparatus comprising a compressor, a condenser, a drier, an expander, and an evaporator, and the hermetic electric compressor according to claim 1. Since the vibration of the compressor is small, the noise of the refrigeration system is suppressed to a low level, and pipe breakage is less likely to occur.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of a hermetic electric compressor according to the present invention will be described below with reference to the drawings. The same components as those in the conventional example are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 1 is a sectional view of a hermetic electric compressor according to the present invention, and FIG. 2 is a vibration characteristic diagram showing a relationship between an operating frequency and an amplitude of the compressor.

In FIG. 1, 101 is a closed container for storing refrigerating machine oil 102. Reference numeral 105 denotes an electric element and the stator 10
3 and a rotor 104 containing a permanent magnet.
106 is a compression element, which is constructed above the electric element 105,
Driven by an electric element 105, both of which are closed containers 10
It is housed in 1. Further, this hermetic electric compressor is R60, which is a typical refrigerant of hydrocarbon refrigerants having a low global warming potential.
Compress 0a.

Details of the compression element 106 will be described below.

A crankshaft 110 has a main shaft portion 111 into which the rotor 5 is press-fitted and fixed, and an eccentric portion 112 formed eccentrically with respect to the main shaft portion 111. Reference numeral 120 denotes a cylinder block, which has a substantially cylindrical compression chamber 122 and a bearing portion 123 that supports the main shaft portion 111.
It is formed below the electric element. A piston 130 is fitted into the compression chamber 122 and is connected to the eccentric portion 112 by a connecting means 131. In order to obtain the same refrigerating capacity as R134a used in the conventional example in R600a, the amount of eccentricity of the eccentric portion 112 and the outer diameter of the piston 130 are much larger than those in the conventional example. 133 is a balance weight in which iron plates are laminated and is fixed to the rotor 104. A valve plate 135 seals the end surface of the compression chamber 22, and a head 136 forms a high-pressure chamber, which is fixed to the valve plate 135 on the side opposite to the compression chamber 122. A suction tube 139 is fixed to the closed container 1 and is connected to the low-pressure side (not shown) of the refrigeration cycle to guide a refrigerant gas (not shown) into the closed container 101. A suction muffler 140 forms a sound deadening space 142.

150 is a suspension spring.
Are provided at four locations centering on the cross section of No. 1, and are fitted between the snubb bar 152 fixed to the closed container 101 and the snubb bar 153 fixed to the stator 103 of the electric element 105, and the compression element 106 and the electric element 105 are attached. The stator 103
It is elastically supported indirectly through.

The operation of the hermetic electric compressor configured as described above will be described below.

Electric power supplied from the commercial power source 62 is supplied to the electric element 105 via the control circuit 61 and the inverter 60, and causes the rotor 104 of the electric element 105 to rotate at an arbitrary rotational speed. The rotor 104 is the crankshaft 110.
And the movement of the eccentric portion 112 is transmitted to the piston 130 via the connecting means 131, so that the piston 130
Reciprocates in the compression chamber 122, and the suction tube 1
The refrigerant gas introduced into the closed container 101 through 39 is sucked from the suction muffler 140,
It is continuously compressed within 2. At this time, the vibration generated by the reciprocating motion of the piston 130 is caused by the balance weight 1
It is offset by 33, but some remain. The remaining vibration is the reaction of the cylinder block 20.
However, since the eccentric amount of the eccentric portion 112 and the outer diameter of the piston 130 are much larger than the hermetic electric compressor shown in the conventional example that compresses the refrigerant R134a, the reciprocating motion of the piston 130 is increased. The vibration energy generated by this is much larger than that shown in the conventional example, and as a reaction thereof, the cylinder block 120 vibrates greatly.

However, this vibration is due to the compression element 106.
The behavior is completely different between the upper part of the and the vicinity of the suspension spring 130. That is, although the vicinity of the cylinder block 120 that directly receives the reaction of the piston 130 vibrates greatly, in the vicinity of the suspension spring 150, since this movement is supported downward via the electric element 105, the vicinity of the suspension spring 150 serves as a fulcrum, and the amplitude is Get smaller. This reduced amplitude is further damped by the suspension spring 150. As described above, the amplitude of the vibration of the hermetic electric compressor generated by the inertia energy due to the reciprocating motion of the piston increases as the rotation speed of the electric element decreases, but according to the present embodiment, the rotation around 27 Hz. At the frequency, it was found to be within the level of 40 μm or less, which is practically no problem.

The verification result of the above mechanism will be described with reference to the vibration characteristic diagram of FIG.

In FIG. 2, B is the result of the compressor shown in the conventional example, the cylinder volume is 5.7 cm ³ , and the refrigerant is R134a.
Is used. C is the conventional configuration, the cylinder volume is expanded to 10 cm ³ , and the measurement is performed using R600a as the refrigerant. A is the compressor according to the embodiment of the present invention, and the cylinder capacity is also expanded to 10 cm ³ to be the refrigerant. It is measured using R600a. The vibration values are the results of lateral vibrations measured near the center of the compressor. From this result, B has a vibration of 32 μm at 27 Hz, and C has a vibration of 2
The vibration at 7 Hz was 65 microns, and the D was 27 microns at 29 microns.

As is clear from the above measured data, in the present invention, a vibration value almost equal to that of the compressor using the conventional R134a is obtained, and low speed operation by the inverter device is realized while using the refrigerant R600a. We were able to.

At this time, also in the efficiency of the compressor which was continuously evaluated, a good result was obtained in which the COP at the rotation frequency near 25 Hz exceeded 1.3. The refrigerating machine oil used for this verification test is an alkylbenzene type refrigerating machine oil which has already been put to practical use in Europe and the like, and has a viscosity of 10 cSt at 40 ° C. Normally, when the compressor is operated at a low speed, the work of the compressor is small, and as a result, the calorific value from the compressor is small, and the temperature of the refrigerating machine oil that is strongly affected by this heat in the sealed container also has a small rise .

In the present embodiment, the refrigerating machine oil having a relatively low viscosity suppresses the viscous resistance in the sliding portion of the compressor to a small level, and the temperature rise is small under the low rotation speed operation. It is speculated that good efficiency results were obtained due to the synergistic effect of the small leakage during 130. From the above results, the viscosity is 7 to 32 cSt
It is presumed that similarly good efficiency results can be obtained within the range. In the evaluated compressor, the clearance between the compression chamber 122 and the piston 130 is controlled to 5 to 10 μm, which is also a factor that the leakage between the compression chamber 122 and the piston 130 is suppressed to be small. Conceivable. Further, the evaluated compressor has a ratio of the outer diameter of the piston to the distance of the reciprocating motion of about 1.5: 1, which keeps the outer diameter of the piston relatively small. It is considered that the leakage was suppressed to a small level, and it is estimated that by lowering this ratio to the vicinity of the normally designed ratio of about 1: 1, better efficiency results can be obtained.

FIG. 3 is a block diagram of a refrigerating apparatus according to the present invention. In FIG. 3, 170 is a compressor, 180 is a condenser, and 1
Reference numeral 85 is a dryer, 187 is an expander, and 189 is an evaporator, which are fluidly connected by piping by welding such as brazing. Further, the compressor 170 is defined by claim 1 of the present invention.
It is described in. In the above configuration, since the vibration of the compressor is within a practically no problem level, specifically, 40 μm or less, the vibration force to the refrigeration system is small, and therefore the refrigeration system resonates. It is possible to prevent abnormal noise. Also, as described above, the components of the refrigeration system are connected by piping by welding such as brazing, but if repeated stress due to large vibration is applied to this brazed part, cracks may occur due to fatigue. There is. However, in this embodiment, since the vibration of the compressor is small, the stress amplitude of repetitive stress is small, and as a result, the occurrence of cracks due to fatigue is suppressed, pipe breakage is less likely to occur, and a highly reliable refrigeration system can be obtained. it can.

[0033]

As described above, the invention according to claim 1 uses a refrigerant whose main component is a hydrocarbon refrigerant whose main component is R600a, and uses a plurality of operating frequencies including rotation speeds lower than the frequency of the commercial power source. An inverter-driven reciprocating hermetic electric compressor driven by, wherein the compression element is constructed substantially above the electric element, and the compression element is through a stator,
By being elastically supported from the closed container below the stator, it is possible to realize a hermetic electric compressor with low vibration, low noise, and high efficiency.

The invention according to claim 2 is a compressor,
A refrigeration system provided with a condenser, a drier, an expander, and an evaporator, wherein the hermetic electric compressor according to claim 1 is used, and a refrigeration system with low noise and high reliability is provided. Obtainable.

[Brief description of drawings]

FIG. 1 is a sectional view of a hermetic electric compressor according to the present invention.

FIG. 2 is a vibration characteristic diagram of the hermetic electric compressor according to the present invention.

FIG. 3 is a block diagram of a refrigerating apparatus according to the present invention.

FIG. 4 is a sectional view of a conventional hermetic electric compressor.

[Explanation of symbols]

60 inverter device 61 Control circuit 101 airtight container 102 Refrigerator oil 105 Electric element 106 compression element 130 pistons 150 suspension spring 170 compressor 180 condenser 185 dryer 187 expander 189 evaporator

Claims (2)

[Claims] 1. An R600a is mainly provided while accommodating refrigerating machine oil, a compression element including a piston that reciprocates in a compression chamber, and an electric element composed of a stator and a rotor for driving the compression element in a closed container. Using a refrigerant containing a hydrocarbon refrigerant as a main component, which is an inverter-driven reciprocating hermetic electric compressor driven at a plurality of operating frequencies including a rotational frequency lower than a commercial power supply frequency, wherein the compression element is A hermetic electric compressor, which is constructed substantially above the electric element, and wherein the compression element is elastically supported from the hermetic container below the stator via the stator. 2. A refrigerating apparatus comprising a compressor, a condenser, a drier, an expander, and an evaporator, wherein the hermetic electric compressor according to claim 1 is used as the compressor.