JPH0473055B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is a compressor drive control device, in particular, a vibration type compressor, in which the frequency of an AC power source supplied to a vibratory compressor is controlled by the temperature of the refrigerant sucked by the compressor. The present invention relates to a compressor drive control device that controls the drive to operate at maximum efficiency with a simple configuration by correlating the temperature of refrigerant discharged by the compressor.

[Conventional technology]

There is a refrigerator that compresses and liquefies a gaseous refrigerant using a vibrating compressor, and performs cooling etc. using the heat of vaporization when the liquefied refrigerant evaporates. Conventionally,
An example of a vibrating compressor drive control device used in the refrigerator is shown in FIG. The vibrating compressor 5 shown in FIG. 4 connects the DC power V to the primary windings of the transformer 4 with different polarities by alternately switching the switching transistors TR ₁ and TR ₂ into conduction states. is applied alternately, and the drive is controlled so that a resonance state, that is, maximum efficiency is obtained. At this time, switching transistors TR ₁ and TR ₂
is alternately switched between a conducting state and a non-conducting state in a manner such as the current waveform shown in FIG. 5, for example, and the switching frequency is controlled to match the resonant frequency of the vibrating compressor 5. To be more specific, in order to switch the collector current “I _C ” in Fig. 5,
A base current "I _B " is alternately supplied from the drive circuit 1-3 to the bases of the switching transistors TR ₁ and TR ₂ . That is, the base current “I _B ”
By supplying a so-called trapezoidal waveform as shown in the figure as a current waveform obtained by multiplying the current amplification factor "h _FE ," I _C ≥ h _FE × I _B at points P ₁ to P ₃ in the figure, respectively. By giving conditions, the switching transistors TR ₁ and TR ₂ are alternately switched between conductive and non-conductive states to obtain a driving power source with a desired frequency. The compressor 5 was driven using a drive power source that matched the resonant frequency of the compressor 5.

[Problem that the invention seeks to solve]

As explained above, the current of the vibrating compressor 5 is
When a switching transistor, etc. is controlled to be switched between a conducting state and a non-conducting state under the condition of I _C ≧h _FE ×I _B , first, the switching transistor, etc. is switched between a conducting state and a non-conducting state. There is a problem in that the signal required to determine the timing for switching the state is affected by ripples, causing fluctuations in the timing. Second, as shown in FIG. 5, the timing at which the switching transistor becomes non-conductive varies depending on the current amplification factor "h _FE " of the transistor.
It is necessary to match the values of the current amplification factors "h _FE " of the transistors that alternately switch to a conductive state/non-conductive state. In addition, the vibrating compressor 5 may not be able to be driven at maximum efficiency at all times due to fluctuations in the current amplification factor "h _FE " due to temperature, changes over time, etc. There was a problem with this.

Furthermore, conventionally, attention has been paid to the fact that the resonant frequency in a vibratory compressor changes in response to the temperature and pressure of the refrigerant, and consideration has been given to controlling vibrations in the compressor. But in this case,
The use of a single sensor, so to speak, was only considered, and it was not possible to properly deal with changes in temperature and pressure.

In order to solve these points, we discovered that both the discharge pressure and suction pressure in a vibrating pressure machine are involved in the spring constant of the compressor, and
detecting the pressure of the refrigerant sucked by the vibrating compressor 5 and the discharge pressure of the refrigerant discharged;
A device is being considered that controls the frequency of the driving power supplied to the compressor 5 in relation to the detected pressure, but the pressure detectors for detecting the suction pressure and the discharge pressure are connected to the compressor 5 in a so-called sealed state. It is assumed that there are problems in that the structure needs to be attached and the structure becomes complicated and expensive.

[Means for solving problems]

In order to solve the above-mentioned problems, the present invention grasps the pressure of the refrigerant taken in by a vibrating compressor based on the temperature of the refrigerant, and also measures the pressure of the refrigerant compressed and discharged by the compressor. By adopting a configuration in which the temperature of the refrigerant is determined and the compressor is driven using a drive power source with a frequency corresponding to at least both temperatures, the compressor can be driven with a simple configuration and maximum efficiency. Therefore, the compressor drive control device of the present invention is a compressor drive control device that controls the drive of a vibrating compressor using a predetermined frequency corresponding to the load. a suction refrigerant temperature detector that detects a temperature corresponding to the vapor pressure; a discharge refrigerant temperature detector that detects a temperature corresponding to the saturated vapor pressure of the refrigerant compressed and discharged by the compressor; and the suction refrigerant temperature. a temperature detection unit that calculates the sum of temperature signals respectively detected by the detector and the discharge refrigerant temperature detector; The drive power generation section includes a calculation section that generates an output related to a spring constant (K _PS +K _Pd ), and a drive power generation section that generates a drive voltage of a predetermined frequency determined based on the output from the calculation section. The compressor is characterized in that the compressor is driven using the driving power generated by the compressor.

〔Example〕

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a block diagram of essential parts of the embodiment of the present invention shown in FIG. 1, and FIG. 3 is a temperature/pressure conversion characteristic diagram.

In the figure, 1 is a control circuit, 1-1 is a temperature detection section, 1
-2 is a calculation unit, 1-3 is a drive circuit, 2 and 3 are temperature detectors, 4 is a transformer, 5 is a compressor, 6 is a condenser, 7 is a pressure reducer, 8 is a refrigerator, and 8-1 is an evaporator represents.

In FIG. 1, a control circuit 1 includes a temperature detection section 1-1, a calculation section 1-2, and a drive circuit 1-3.
A temperature detector (T _s ) 2 is configured to detect the temperature corresponding to the saturated vapor pressure of the refrigerant taken in by the compressor 5, and the saturation of the refrigerant compressed and discharged by the compressor 5. This is for supplying a drive signal of such a frequency that the compressor 5 is driven in a resonant state based on the respective signals from the temperature detector (T _d ) 3 that detects the temperature corresponding to the vapor pressure. It should be noted that the temperature detected by the temperature detection unit 1-1 is considered to correspond to the pressure of the refrigerant on the suction side and the pressure of the refrigerant on the discharge side, as will be described later with reference to FIG. good.

The vibrating compressor 5, supplied with drive power generated by the drive signal supplied from the control circuit 1, compresses the refrigerant and supplies a mixture of gas and liquid to the condenser 6. It releases heat and liquefies it. Then, the liquefied refrigerant passes through the pressure reducer 7 and is vaporized in the evaporator 8-1 provided in the refrigerator 8, and removes the heat of vaporization.
It is for cooling. The refrigerant that has absorbed the heat of vaporization is compressed again by the compressor 5. By repeating the closed cycle as described above, the heat taken from the evaporator 8-1 is released from the condenser 6 in the form of heat.The operation of the control circuit 1 will be described in detail below.

In the figure, a temperature detection section 1-1 is for converting signals detected by temperature detectors (for example, thermistors) 2 and 3 into predetermined electrical signals.

In the figure, the calculation section 1-2 causes the compressor 5 to resonate based on the "temperature corresponding to the suction pressure" and "temperature corresponding to the discharge pressure" converted into electrical signals by the temperature detection section 1-1. The purpose is to generate a voltage corresponding to the frequency of driving in the state. and,
The drive circuit 1-3 supplies a drive signal with a frequency corresponding to the voltage supplied from the calculation unit 1-2 to the transistors TR ₁ and TR ₂ in the figure, and supplies the DC power supply V _CC to the transistor 1 of the transformer 4. This is for supplying current to the next winding in the form of a so-called rectangular wave in which the polarity is alternately switched to the windings having different polarities. The AC voltage obtained from the secondary winding of the transformer 4 is supplied to the compressor 5, and the compressor 5 is always driven in a resonant state, that is, driven at maximum efficiency.

The manner in which the compressor 5 is driven and controlled in a resonant state will be described in detail below with reference to FIG.

Temperature detectors 2 and 3, temperature detection section 1- in Figure 2
1. The arithmetic unit 1-2, drive circuit 1-3, transformer 4, and compressor 5 are the same as those shown in FIG. 1, or specific examples thereof are shown.

First, the resonant frequency f of the vibrating compressor 5 is expressed as in the following equation.

f=A(K/M) ^1/2 (1) Here, A is a constant, M is the mass of the piston constituting the compressor 5, and K is a spring constant. Also,
The spring constant K can be expressed as shown below.

K = K ₁ × 2 + K _ps + K _pd ... (2) Here, K ₁ is the spring constant of each of the pistons that support the compressor 5 from both sides, K _ps is a constant determined by the refrigerant to be drawn, and K _pd represents a constant determined by the discharged refrigerant.

Therefore, as is clear from the previous equations (1) and (2),
For example, as the suction pressure of the refrigerant drawn into the compressor 5 and the discharge pressure of the compressed and pumped refrigerant increase, the resonance frequency of the compressor 5 increases. For this reason, as in the present invention, the refrigerant taken in by the compressor 5 is related to the "suction pressure calculated from the temperature" and the refrigerant compressed and discharged by the compressor 5 to the "discharge pressure calculated from the temperature". By controlling the frequency of the driving power supplied to the compressor 5, the compressor 5 is always operated at the resonant frequency, that is, maximum efficiency, without being affected by the load of the compressor 5.
It becomes possible to drive.

Next, the operation of the configuration shown in FIG. 2 will be explained.

In the figure, the temperature (T _s ) signal of the sucked refrigerant and the temperature (T _d ) signal of the discharged refrigerant detected by temperature detectors 2 and 3 are detected by the respective operational amplifiers in the temperature detection section 1-1. The signals are respectively input to the positive polarity terminals and predetermined amplification is performed. For each of the amplified signals, "K _ps +K _pd " in equation (2) is computed by a resistor network as shown in the figure in the computing section 1-2.
Then, the calculated signal is transmitted to the drive circuit 1-3.
, and voltage/frequency conversion is performed into a rectangular signal with a frequency corresponding to the signal. The voltage/frequency converted rectangular signal is supplied to TR ₁ and TR ₂ in the figure, and a current with alternating polarity is supplied from the DC power supply V _cc to the primary winding of the transformer 4, respectively. Then, the AC voltage obtained from the secondary winding of the transformer 4 is supplied to the compressor 5. As described above, the frequency of the driving power source that drives the compressor 5 is always set in relation to the pressure of the refrigerant sucked into the compressor 5 and the pressure of the refrigerant compressed and discharged by the compressor 5. It becomes possible to perform drive control in a state of resonance, that is, a state of maximum efficiency.

Figure 3 shows a conversion characteristic diagram for converting the temperature of the refrigerant into pressure.
The conversion characteristic diagram of is shown. The horizontal axis in the figure indicates “℃”.
The vertical axis indicates pressure per unit area "Kg/CM ² ". By using the temperature/pressure conversion characteristic diagram shown in FIG. 3, the pressure of the refrigerant can be converted from the temperature value detected using the temperature detectors 2 and 3 in FIGS. 1 and 2. Become. As the temperature detectors 2 and 3, inexpensive and easy-to-install devices such as thermistors and thermocouples are generally used.

〔Effect of the invention〕

As explained above, according to the present invention, the temperature corresponds to the saturated vapor pressure of the refrigerant taken in by the vibratory compressor and the saturated vapor pressure of the refrigerant compressed and discharged by the compressor. The configuration uses a configuration that generates drive power with a predetermined frequency based on temperature and supplies the generated drive power to the compressor, so the compressor can be driven with a simple configuration using an inexpensive temperature sensing element. In addition, the compressor can be driven and controlled at maximum efficiency at all times.

[Brief explanation of the drawing]

Fig. 1 is a configuration diagram of one embodiment of the present invention, Fig. 2 is a configuration diagram of main parts of one embodiment of the present invention shown in Fig. 1, Fig. 3 is a temperature/pressure conversion characteristic diagram, and Fig. 4 is a conventional diagram. FIG. 5 is an explanatory diagram illustrating the operation of the compressor drive control device shown in FIG. 4. In the figure, 1 is a control circuit, 1-1 is a temperature detection section, 1
-2 is a calculation unit, 1-3 is a drive circuit, 2 and 3 are temperature detectors, 4 is a transformer, 5 is a compressor, 6 is a condenser, 7 is a pressure reducer, 8 is a refrigerator, and 8-1 is an evaporator represents.

Claims (1)

[Claims] 1. In a compressor drive control device that controls the drive of a vibrating compressor using a predetermined frequency corresponding to the load, the frequency corresponds to the saturated vapor pressure of the refrigerant sucked by the compressor. a suction refrigerant temperature detector that detects temperature; a discharge refrigerant temperature detector that detects a temperature corresponding to the saturated vapor pressure of the refrigerant compressed and discharged by the compressor; and the suction refrigerant temperature detector and the discharge refrigerant. A temperature detection unit that calculates the sum of temperature signals respectively detected by the refrigerant temperature detector; and an output () related to the spring constant of the compressor based on the value of the result added by the temperature detection unit. K _PS +K _Pd A compressor drive control device, characterized in that the compressor is driven using a drive power source.