JPS6262274B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cooling system, in particular a vibratory compressor, in which at least two controllers are turned on and off alternately and output a current at a level proportional to the level of control current supplied to the controller. In a cooling device equipped with an inverter circuit having a semiconductor element, the control current is controlled in accordance with the ambient temperature of the cooling device to reduce the vibration stroke of the compressor, and furthermore, for example, the cooling device has an extremely low temperature. The present invention relates to a cooling device that prevents a compressor from being undesirably damaged when placed at ambient temperatures.

In general, in a cooling system equipped with a vibratory compressor and an inverter circuit, the cooling system is operated at an extremely low ambient temperature (hereinafter referred to as a low temperature state), as described in the patent application specification of Japanese Patent Application No. 52-75142.
It has been found that when the compressor is placed and operated, the vibration stroke of the compressor increases undesirably, causing damage to the valve chamber. Further, even when the ambient temperature does not reach the extremely low ambient temperature described above, the elasticity of the refrigerant when compressed tends to be small, and the vibration stroke of the compressor tends to become undesirably large.

The present invention aims to solve the above points,
In a cooling device in which an inverter circuit is configured to output a current at a level corresponding to a control current level supplied to a control section of a semiconductor device with a control section, as the ambient temperature of the cooling device falls, the output of the inverter increases. The purpose is to reduce the level. Furthermore, if necessary, when the cooling device is placed in a low temperature state, the control current level is maintained at zero level, thereby reducing the output voltage of the inverter circuit, that is, the input voltage of the compressor to zero, and preventing the compressor from undesirably operating. The purpose is to prevent the compressor from being destroyed and to automatically start supplying power to the compressor when the ambient temperature returns from a low temperature state to a normal temperature state. The present invention will be described below with reference to the drawings.

Figure 1 is an explanatory diagram explaining the principle of the present invention, Figure 2
The figure shows the configuration of an embodiment of a cooling device according to the present invention.

FIG. 1 shows the output voltage of the inverter circuit, ie, the input voltage characteristic of the compressor, with respect to the ambient temperature.
In the figure, line A represents an example of ambient temperature/limit input voltage characteristics. That is, line A represents the limit of input voltage at which the compressor valve chamber is destroyed relative to ambient temperature.
Line B represents an example of the low-temperature limit ambient temperature characteristic. For example, when the ambient temperature is below the temperature value shown by line B, that is, the indicated temperature _T0 , the vibration stroke of the compressor increases rapidly and the valve chamber becomes undesired. This corresponds to the limit temperature T ₀ at which damage is likely to occur. Further, line C shows an example of the high temperature side limit ambient temperature characteristic, for example, the ambient temperature is the temperature value according to line C, that is, the indicated temperature T ₁
This corresponds to the limit temperature T ₁ at which the windings of the compressor are likely to be undesirably burnt out.

In the case of the present invention, (1) When the ambient temperature is at normal temperature, that is, between the indicated temperature T ₀ and the indicated temperature T ₁ , the compressor is driven based on the characteristics shown by the indicated line D ₁ . Furthermore, (2) when the ambient temperature becomes a low temperature state, that is, below the indicated temperature T ₀ , the input voltage is forcibly reduced to zero level as shown by the indicated line D ₂ to stop driving the compressor. Furthermore, (3) when the ambient temperature is in a high temperature state, that is, above the indicated temperature _T1 , the input voltage is maintained at a predetermined level as shown by the indicated line _D3 . Further, in (2) above, when the ambient temperature returns to normal temperature, the input voltage is automatically restored to drive the compressor again.

FIG. 2 shows the configuration of an embodiment of the cooling device according to the present invention. In the figure, 1 is a vibration compressor driven by AC, 2 is an inverter circuit, 3 is a control current control circuit according to the present invention, 4 is a temperature detection section according to the present invention,
5 and 6 are power supply terminals of the DC power supply, 7 is a winding on the inverter output terminal side, 8 is a secondary winding, T is a transformer, and TR1 and TR2 are semiconductor elements with a control unit that are turned on and off alternately, for example. transistor,
TR3 and TR4 are the transistors TR1, respectively.
and a transistor Darlington-connected to TR2, TR5 is a main switching element according to the present invention, such as a transistor, and TR6 is a transistor connected to TR2.
Transistor that controls the base current of 5, TR7
is a transistor that controls the base current of the transistor TR6; TR8 and TR9 are transistors that supply base current to the transistors TR3 and TR4, respectively; C1 is a capacitor that determines the switching period of the transistors TR1 and TR2; C2 is a transistor that controls the base current of the transistor TR6; is a smoothing capacitor for smoothing the power supply voltage, TH1 is the first thermistor according to the present invention, which has a characteristic that the resistance value increases as the ambient temperature falls, and TH2 is the second thermistor according to the present invention. It is a thermistor and has the characteristic that the resistance value becomes almost zero when the ambient temperature falls below the temperature _T shown in Figure 1. R1 and R2, which are turned on when the voltage is ₁ or more, represent resistances, respectively.

In inverter circuit 2, transistor TR
1, TR3, TR8 and transistors TR2, TR4,
TR9 is repeatedly turned on and off alternately.
When the transistors TR1, TR3, and TR8 are in the on state and the transistors TR2, TR4, and TR9 are in the off state, a current α is supplied to the winding 7 on the inverter output terminal side as shown by the solid line in the figure; TR1, TR3, TR8 are in the off state and transistors TR2, TR4,
When TR9 is in the on state, current β is supplied to the winding 7 on the inverter output terminal side as shown by the broken line in the figure. By alternately supplying the current α shown by the solid line and the current β shown by the broken line to the winding 7 on the inverter output terminal side, an AC voltage is generated in the secondary winding 8 via the transformer T. The compressor 1 is driven by alternating current. This transistor TR
1, TR3, TR8 and transistors TR2, TR
4. The switching operation of TR9 is performed based on the charging/discharging current waveform of capacitor _C1 as shown by waveform a in the figure. Further, the current α, that is, the current level of the transistor TR1, is proportional to the base current of the transistor TR3, that is, the control current, and the current β, that is, the current level of the transistor TR2, is proportional to the base current, that is, the control current of the transistor TR4. .

The control current control circuit 3 determines the control current level in accordance with the ambient temperature. That is, (1)
When the ambient temperature is at normal temperature, the control current level is decreased (or increased) as the ambient temperature decreases (or increases), and the output level of the inverter 2 is decreased (or increased); (2) (3) When the ambient temperature is low, the control current level is set to zero to bring the output level of the inverter 2 to zero, and (3) when the ambient temperature is high, the control current level is maintained at a predetermined level. The output level of inverter 2 is kept constant. Also (2) above
In this state, when the ambient temperature returns to normal temperature, the output level of the inverter 2 is automatically restored. The circuit operation of the control current control circuit 3 will be explained below.

[] When the ambient temperature is at room temperature, the transistor TR8 shown by the illustrated waveforms b and c
A current proportional to the collector current of the transistor TR9 and the collector current of the transistor TR9 flows through the series circuit of the resistor R1 and the first thermistor TH1. The transistor TR7 is kept on for a period when the voltage between the terminals of the first thermistor TH1 exceeds the Zena voltage of the Zena diode ZD1, and the amount of conduction is determined in proportion to the voltage between the terminals of the first thermistor TH1. That is, the collector current of the transistor TR7 corresponds to the shaded portion in the illustrated waveforms b and c. Here, the current level L in the illustrated waveforms b and c is determined based on the resistance value of the first thermistor TH1, and decreases (or increases) as the resistance value of the thermistor TH1 increases (or decreases). )do.
The collector current of the transistor TR6 is proportional to the collector current of the transistor TR7, and the collector current of the transistor TR5 is proportional to the collector current of the transistor TR6. Therefore, the collector current waveform of the transistor TR5 becomes as shown in the illustrated waveform d. Therefore, the base currents, that is, the control currents of the transistors TR3 and TR4 become as shown by waveforms e and f in the diagram. In this way, in the normal temperature state, the control current control circuit 3 increases (or decreases) the control current level as the ambient temperature increases (or decreases). That is, the output level of the inverter circuit increases (or decreases) as the ambient temperature increases (or decreases).

[] When the ambient temperature becomes low, the resistance value of the second thermistor TH2 decreases significantly, and the collector currents of the transistors TR8 and TR9 are all bypassed to the control current control circuit 3. Therefore, transistor TR3
Then, the base current, that is, the control current, is no longer supplied to the transistor TR4, and the output level of the inverter circuit 2 becomes zero. Then, when the ambient temperature recovers from the low temperature state to the normal temperature state, the second
The resistance value of the thermistor TH2 increases, the control current control circuit 3 again performs the above operation [], and the output level of the inverter circuit 2 is restored.

[] When the ambient temperature is high, the resistance value of the first thermistor TH1 is decreased and the
Diode ZD2 is turned on, and the collector current of transistor TR7 is maintained at a predetermined level. Therefore, the collector current of transistor TR5 is maintained at a predetermined level, and the transistor
The base currents of TR3 and transistor TR4 are maintained at predetermined levels. Therefore, the output level of inverter circuit 2 is maintained at a predetermined level.

As described above, according to the present invention, the output level of the inverter circuit can be lowered as the ambient temperature falls. Further, when the cooling device is placed in a low temperature state, the supply of electric power to the compressor is stopped, so that it is possible to prevent the compressor from being undesirably destroyed. Furthermore, when the ambient temperature returns to normal temperature, power supply to the compressor can be automatically restarted. Further, when the ambient temperature is high, the power supplied to the compressor is maintained at a predetermined level, so that it is possible to prevent the compressor windings from being undesirably burnt out.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram explaining the principle of the present invention, Figure 2
The figure shows an embodiment of the invention. In the figure, 1 is a compressor, 2 is an inverter circuit, 3 is a control current control circuit, 4 is a temperature detection section, TR1, TR
2 is a semiconductor element with a control section, TR5 is a main switching element, TH1 is a first thermistor, TH2
represents the second thermistor.

Claims (1)

[Scope of Claims] 1. A vibrating compressor and at least two semiconductor devices with control units that are turned on and off alternately, converting DC power into AC power, and supplying the AC power to the vibrating compressor. In the cooling device, the inverter circuit is configured to have an output current level determined according to a control current level supplied to the control section of the semiconductor device with a control section. A control current control circuit is provided that determines the control current level in response to temperature, and the control current control circuit is configured to reduce the control current level as the ambient temperature falls. cooling device. 2. The cooling device according to claim 1, wherein the control current control circuit is configured to maintain the control current level at a zero level when the ambient temperature is below a predetermined temperature value. . 3. The control current control circuit is configured to automatically start supplying the control current when the ambient temperature returns to above the predetermined temperature value. cooling system. 4. The control current control circuit includes a temperature detection section including a first thermistor that takes a resistance value corresponding to the ambient temperature, and a current having a level value corresponding to a detection signal from the temperature detection section. Claims further comprising: a main switching element for determining a control current level; and a second thermistor for shorting the main switching element when the ambient temperature is below the predetermined temperature value. The cooling device according to item 3.