JPS6342176B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a compressor protection device, and particularly to a protection device for preventing insufficient lubrication of the compressor due to insufficient refrigerant in a refrigeration circuit including the compressor, and promoting extension of the life of the compressor. Regarding equipment. For example, in a vehicle air conditioner, the compressor for compressing the refrigerant circulating in the refrigeration circuit is
Lubricating oil is required to lubricate each sliding part, but in response to the recent demands for lighter weight and higher performance, oil pumps for forced lubrication have been abolished.
It has become common practice to skillfully guide refrigerant containing lubricating oil to each sliding part within the compressor to provide lubrication. However, with this lubrication technology, if the refrigerant leaks due to damage to the pipes or insufficient sealing of each sealing part, and the absolute amount of refrigerant in the refrigeration circuit becomes insufficient, the refrigerant is removed as an intermediary. As a result, the amount of lubricating oil delivered to each sliding part of the compressor becomes insufficient, which accelerates the wear of each sliding part, and in the worst case, damages the compressor due to seizure, etc. This would have caused an accident. In addition, when the air conditioner is used for cooling, if there is a shortage of refrigerant in the refrigeration circuit, the operator can detect this as a phenomenon in which the cooling capacity has decreased, so the compressor should not be operated after that. If the air conditioner is not used for cooling, but only for dehumidification, the operator may no longer be able to operate the refrigeration circuit. Unable to detect the lack of refrigerant inside, the compressor eventually breaks down. However, as in the former case, even if it were possible to avoid compressor damage accidents, the wear of each sliding part would inevitably accelerate, which would significantly reduce the durability of the compressor. It lowers the Therefore, in order to eliminate the above-mentioned drawbacks, the warning device is activated by a switch that closes when the expansion valve conventionally installed in the middle of the refrigeration circuit reaches its maximum opening, or the warning device is activated by the activation of the switch. Then,
A configuration has been proposed in which the excitation circuit of the electromagnetic clutch for transmitting driving force to the compressor is short-circuited, and the fuse installed in the circuit is cut, thereby forcibly stopping the operation of the compressor. When the compressor is started, the expansion valve may be at its maximum opening for a relatively short time at the beginning, so a delay device is used to prevent the protection device from operating for the short time. This was the current situation. However, this conventional device still has the following drawbacks. As mentioned above, the expansion valve reaches its maximum opening when the compressor is started, but the response of the thermosensor cylinder is relatively slow, so a relatively long delay device is required, and even during continuous operation. When the refrigeration load becomes extremely large and the expansion valve reaches its maximum opening, the protection device is activated even though there is a sufficient amount of refrigerant in the refrigeration circuit. Ta. That is,
In such cases, unnecessary inspections and unnecessary replacement of the fuse for the excitation circuit of the electromagnetic clutch are required each time, which is extremely complicated and uneconomical. In view of the above-mentioned drawbacks, the present invention provides a compressor protection device that operates only when two types of abnormalities are detected in the refrigeration circuit, and that operates only when the amount of refrigerant in the refrigeration circuit is truly insufficient. It was done for that purpose. The present invention will be explained in detail below based on the illustrated embodiments. In the figure, reference numeral 1 denotes, for example, a vehicle running engine which serves as a drive source for a compressor 2, and the engine 1 and the compressor 2 are connected by a belt 4 via an electromagnetic clutch 3. The electromagnetic clutch 3
An excitation circuit is formed in which the excitation coil is connected to a power supply 6 via a fuse 5, and an ON-OFF switch (not shown) and a temperature detection switch are installed in the excitation circuit and can be operated from the driver's seat. A switch (not shown) controls the operation of the electromagnetic clutch 3 and thus the compressor 2. The discharge side of the compressor 2 is connected to a condenser 7, followed by a liquid receiver 8, an expansion valve 9, an evaporator 10 and a compressor 2.
A refrigeration circuit is formed by sequentially connecting the suction side of the The expansion valve 9 is configured so that a temperature sensing cylinder 11 disposed near the outlet of the evaporator 10 detects the temperature of the refrigerant in the pipe line, and the fluid pressure inside the temperature sensing cylinder 11 changes accordingly, and the pressure equalizing pipe 12 The opening degree of the valve 14 is adjusted by the movement of the diaphragm 13, which is displaced by the pressure difference between the pressure of the refrigerant in the conduit near the outlet of the evaporator 10, and the optimal refrigerant flow rate according to the refrigeration load is obtained. It is composed of In a known refrigeration circuit configured as described above, the first embodiment of the present invention shown in FIG. A second switch 1 that closes when the pressure on the outlet side of 9 or inside the evaporator 10 (low pressure side refrigeration circuit pressure) falls below a set value.
6 are connected in series to constitute a circuit A that short-circuits the excitation circuit. It should be noted that when the short circuit A becomes conductive, an excessive current flows and the fuse 5 blows, the excitation circuit becomes open, and the compressor becomes unable to operate. Here, the first switch 15 is composed of a contact 15a attached to the diaphragm 13 and a contact 15b attached to the expansion valve body, and these two contacts are insulated by an insulating material 15c.
When the diaphragm 13 is pushed down to the lower end and the expansion valve 9 reaches its maximum opening, the two contacts can come into contact with each other and are electrically connected. Further, the second switch 16 has a switch body 16a that introduces the refrigerant pressure on the outlet side of the expansion valve 9 or in the evaporator 10, and contacts 16b and 16c arranged in the switch body 16a are connected to the switch body 16a. When the contact piece 16e attached to the tip of the bellows body 16d disposed inside comes into contact with the bellows body 16d, a conductive state is established. At this time, bellows body 1
The inside of 6d is hermetically isolated from the fluid in the outer circumference (the refrigerant on the outlet side of the expansion valve 9 or in the evaporator 10), and is in a direct air state or a constant pressure state, and as a result, the fluid pressure in the outer circumference (the above-mentioned refrigerant pressure), thereby expanding and contracting the contact piece 16.
e moves forward and backward toward the contacts 16b and 16c.
That is, as the pressure of the refrigerant decreases, the contact piece 16e advances toward the contacts 16b, 16c, and when the pressure falls below the set value, the contact piece 16e and the contacts 16b, 16c come into contact with each other. The contacts 16b and 16c become conductive. In the second embodiment of the present invention shown in FIG.
A third switch 17 having the same configuration as the second switch 16 in the first embodiment is connected in series with the second switch 16 which closes when the pressure in the inlet side or the condenser 7 (pressure in the high pressure side refrigeration circuit) falls below a set value. A circuit A is configured which is connected to the excitation circuit and short-circuits the excitation circuit. The third switch 17 is slightly different from the second switch 16 in that it operates in response to changes in pressure on the inlet side of the expansion valve 9 or in the condenser 7, and all other configurations are the same as in the first embodiment. The same is true. In the third embodiment of the present invention shown in FIG. 3, a first switch 15 similar to the first embodiment that closes when the expansion valve 9 reaches its maximum opening, and A fourth switch 18 that closes when the pressure difference on the outlet side (the pressure difference between the high pressure side and the low pressure side of the refrigeration circuit) becomes less than a set value is connected in series to form a circuit A that short-circuits the excitation circuit. has been done. Here, the fourth switch 18 is a switch body 1 having a cylinder 18b in which a piston 18a can slide.
8c, and at both ends of the cylinder 18b,
Fluid pressures are introduced at the inlet and outlet sides of the expansion valve 9, respectively. Contact points 18d and 18e are disposed at the end of the cylinder 18b on the side where fluid pressure is applied on the inlet side of the expansion valve 9, and the contacts 18d and 18e are provided by a spring 18f.
A contact piece 18g disposed at the tip of the piston 18a biased in the direction 18e contacts the contacts 18d, 1
It is possible to contact 8e. In other words, the spring 1
By appropriately adjusting the biasing force of 8f, when the pressure difference between the inlet side and the outlet side of the expansion valve 9 becomes less than the set value, the contact piece 18g moves to the contact point 18.
d, 18e, these contacts 18d, 18e
becomes conductive. In the fourth embodiment of the present invention shown in FIG. 4, the first embodiment closes when the pressure in the outlet side of the expansion valve 9 or in the evaporator 10 (pressure in the low pressure side refrigeration circuit) falls below a set value. and a second switch 16 similar to that of the third embodiment, which is closed when the pressure difference between the inlet side and the outlet side of the expansion valve 9 (the pressure difference between the high pressure side and the low pressure side of the refrigeration circuit) becomes equal to or less than a set value. A fourth switch 18 similar to that in the example is connected in series to constitute a circuit A that short-circuits the excitation circuit, and the rest is the same as in each of the above embodiments. The fifth embodiment of the present invention shown in FIG. 5 is a modification of the first embodiment, in which a diaphragm device 19 similar to that in the expansion valve 9 is
The only difference is that a first switch 15 is provided separately and a first switch 15 is provided to the diaphragm device 19, and everything else is the same as the first embodiment. In each of the embodiments having the above configuration, the functions thereof will be collectively described below. First, in what cases each of the above-mentioned switches will be closed will be described as follows. (1) When the refrigeration load is extremely large when the first switch 15 is closed. If the pressure inside the evaporator drops suddenly when the compressor is started. When the amount of refrigerant in the refrigeration circuit is insufficient. (2) When the second switch 16 closes, the refrigeration load is small and the pressure on the low pressure side, that is, the pressure on the expansion valve outlet side or inside the evaporator, decreases. At this time, the second switch 16
The operating point of is set to 0 Kg/cm ² G, for example. When the amount of refrigerant in the refrigeration circuit is insufficient. (3) When the third switch 17 is closed, when the compressor is stopped, the pressure on the high pressure side, that is, the pressure on the expansion valve inlet side or in the condenser, decreases. At this time, the operating point of the third switch 17 is set to, for example, 7 kg/cm ² G. When the amount of refrigerant in the refrigeration circuit is insufficient. (4) When the fourth switch 18 closes, the pressure difference between the high pressure side and the low pressure side disappears when the compressor is stopped. When the amount of refrigerant in the refrigeration circuit is insufficient and the pressure on the high pressure side no longer increases. At this time, the operating point of the fourth switch 18 is set to 7, for example.
Set to a differential pressure of Kg/cm ² . Under such operating conditions of each switch, for each of the above-mentioned embodiments, the operating condition of each of the switches and the conduction state of the short circuit of the excitation circuit in various operating conditions of the compressor 2 are as follows:
When described together, it becomes as shown in Table 1. However, in Table 1, regarding each of the above switches,
A closed state is indicated by a circle, an open state is indicated by a cross, and regarding the short circuit, a conductive state is indicated by a circle, and a non-conductive state is indicated by a cross.

[Table] As is clear from Table 1, under various operating conditions of the compressor 2, if the required amount of refrigerant is present in the refrigeration circuit, the short circuit A will not become conductive. However, if the amount of refrigerant in the refrigeration circuit is insufficient, the short circuit A will always become conductive, the fuse 5 will melt, and as a result, the excitation circuit of the electromagnetic clutch 3 will be cut off, and the compressor 2
The operation of the compressor 2 is immediately stopped, and it is impossible to restart the compressor 2 in this state. After that, the compressor can be operated normally by repairing the refrigerant leak or replenishing the refrigerant, and then replacing the fuse 5. However, in the first and fifth embodiments among the above-mentioned embodiments, the contacts 15a and 15b of the first switch 15 may come into contact and become conductive during startup, so there may be a delay during the short circuit A. It is necessary to insert a device to prevent said short circuit A from becoming conductive for a short period of time during start-up. In each of the above embodiments, as a result of detecting abnormalities at two locations in the refrigeration circuit, the excitation circuit of the electromagnetic clutch 3 is short-circuited, thereby blowing out the fuse 5 to cut off the excitation circuit, and the compression Although we have described a configuration that makes it impossible to operate machine 2, it is also possible to simply replace the short circuit A with a refrigerant shortage warning circuit for activating a warning device such as a warning buzzer or warning lamp. , it is possible to implement the invention. As described above, according to the present invention, the compressor protection device is activated only when two abnormalities are detected in the refrigeration circuit, so that only the case where the amount of refrigerant in the refrigeration circuit is insufficient can be accurately detected. This has the effect of eliminating the need for unnecessary inspections and maintenance, freeing the user from complicated maintenance and management and uneconomical costs, and improving the durability of the refrigerant compressor. Furthermore, the second
- In the fourth embodiment, there is no need for any delay device and the protection device will not be accidentally activated during startup, so it is possible to provide a low cost and highly reliable compressor protection device. It also has the effect that it can be obtained.

[Brief explanation of the drawing]

The figures show embodiments of the present invention, and Fig. 1 shows the first embodiment, Fig. 2 shows the second embodiment, Fig. 3 shows the third embodiment, and Fig. 4 shows the fourth embodiment. FIG. 5 is a circuit diagram showing a fifth embodiment. 2... Compressor, 3... Electromagnetic clutch, 5... Fuse, 9... Expansion valve, 15... First switch, 16... Second switch, 17... Third switch, 18... Fourth switch, A... Short circuit.

Claims (1)

[Claims] 1. A high-pressure side refrigeration circuit that communicates with the discharge side of the compressor, includes a condenser, etc., and communicates with the inlet side of the expansion valve;
a low pressure side refrigeration circuit communicating with the outlet side of the expansion valve and including an evaporator and the like and leading to the suction side of the compressor, an electromagnetic clutch for transmitting driving force to the compressor, and an electromagnetic clutch for controlling the operation of the electromagnetic clutch. rule,
and a refrigeration system equipped with an excitation circuit having a fuse in the circuit, a switch that closes when the pressure in the low pressure side refrigeration circuit falls below a set value, and the pressure in the high pressure side refrigeration circuit falls below the set value. one switch that closes when A protection device for a compressor, characterized in that the excitation circuit is arranged in series in a short-circuiting circuit to form a short-circuit circuit. 2. A high-pressure side refrigeration circuit that communicates with the discharge side of the compressor, includes a condenser, etc., and leads to the inlet side of the expansion valve;
a low pressure side refrigeration circuit communicating with the outlet side of the expansion valve and including an evaporator and the like and leading to the suction side of the compressor, an electromagnetic clutch for transmitting driving force to the compressor, and an electromagnetic clutch for controlling the operation of the electromagnetic clutch. rule,
and a refrigeration system equipped with an excitation circuit having a fuse in the circuit, a switch that closes when the pressure in the low-pressure refrigeration circuit falls below a set value, and a switch that closes when the expansion valve is at its maximum opening, or A short circuit is created by arranging in series in the circuit that shorts the excitation circuit a switch combined with a delay device that closes when the expansion valve is at its maximum opening but delays the closing of the short circuit only when the compressor is started. A compressor protection device characterized by comprising: 3. A high-pressure side refrigeration circuit that communicates with the discharge side of the compressor, includes a condenser, etc., and leads to the inlet side of the expansion valve;
A low-pressure refrigeration circuit that communicates with the outlet side of the expansion valve and includes an evaporator and the like and leads to the suction side of the compressor, an electromagnetic clutch for transmitting driving force to the compressor, and an electromagnetic clutch for controlling the operation of the electromagnetic clutch. rule,
and a refrigeration system equipped with an excitation circuit having a fuse in the circuit, a switch that closes when the pressure in the low-pressure side refrigeration circuit falls below a set value, and a pressure difference between the high-pressure side and the low-pressure side of the refrigeration circuit. A protection device for a compressor, characterized in that a switch that closes when the excitation circuit is below a set value is arranged in series in a circuit that short-circuits the excitation circuit to form a short-circuit circuit.