JPH11139153A - Burning preventing device for air conditioning compressor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device whereby an air conditioning compressor mounted in an automobile is prevented from burning due to refrigerant leakage or the like. SOLUTION: In the vicinity of a refrigerant delivery port of a compressor compressing a refrigerant of an air conditioner for an automobile, a temperature sensor 1 is mounted, also a freeze preventing temperature sensor 2 provided in an outlet of an evaporator is utilized, a control device 11 is provided, which stops operation of the compressor by judging as abnormality when a detection temperature of the temperature sensor 2 of the evaporator is higher than a preset value and a detection value of the temperature sensor 1 mounted in the compressor is also higher than the preset value. In this way, even when dispersion is generated in a temperature of the compressor at operation time, an influence thereof is prevented from being received, only when a trouble of refrigerant leakage or the like is generated, the compressor can be stopped.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-seizure device for an air-conditioning compressor mounted on an automobile.

[0002]

2. Description of the Related Art In an air conditioner for an automobile, both a cooling device and a heating device are operated individually or simultaneously as required to obtain a room temperature set by a driver. Of these, the cooling device drives the compressor with the engine to raise the pressure of the refrigerant, which is liquefied by the condenser,
A cooling cycle is performed in which the refrigerant is guided to an evaporator (evaporator) to evaporate and expand to absorb the surrounding heat with heat of vaporization. The compressor is configured to be connected to the output shaft of the engine via an electromagnetic clutch, and is operated until the temperature detected by the temperature sensor attached to the outlet of the evaporator reaches a set value.

For this reason, when no abnormality such as leakage of the refrigerant occurs, the compressor does not cause seizure. However, when the refrigerant leaks, the compressor is in an under-refrigerant state, and the temperature of the temperature sensor attached to the outlet of the evaporator is reduced. Continuous rotation is performed to continue the operation until the detected temperature falls below the set value. At this time, the temperature of the compressor rises rapidly due to the insufficient circulation of the lubricating oil, which leads to seizure.

Therefore, conventionally, an on / off type temperature switch is screwed around the discharge port of the compressor (where the temperature becomes high), and when the detected temperature (compressor temperature) reaches a certain set value, the electromagnetic clutch is energized. And the operation of the compressor is stopped (for the same technology, see Japanese Patent Application Laid-Open Nos. 60-107414 and 55-130087). When the temperature decreases as the compressor stops, the electromagnetic clutch is energized again to rotate the compressor. As an example of the control temperature in this case, there is a control temperature that turns off at 150 ° C. and turns on when the temperature drops to 130 ° C.

[0005]

As described above, if the compressor is turned on and off only at the temperature near the discharge port, the operation of the compressor is stopped by the electromagnetic clutch before the compressor reaches the seizure temperature. And seizure can be prevented. However, in practice, it has been found that the discharge section temperature of the compressor varies, and even during normal operation, there is a considerable difference depending on the operating conditions. Therefore, in order to prevent the compressor from stopping during normal operation, the temperature at which the compressor is stopped must be set high.

If the temperature at which the compressor is stopped is set to a high value, the temperature switch may not be turned off and the operation may be continued even when the compressor must be stopped in a state of insufficient refrigerant. obtain. When the temperature near the discharge section of the compressor was measured by an experiment, the temperature was 60 to 100 ° C. during normal operation, and 90 to 140 ° C. when the refrigerant was in an insufficient state. For this reason, when the set temperature of the temperature switch is set to 90 ° C., the compressor stops when the temperature exceeds 90 ° C. even during normal operation.

The present invention has been made in view of this point, and a temperature sensor is provided in place of a conventionally used on / off type temperature switch, and a temperature sensor is additionally provided in other parts. An object of the present invention is to provide an air conditioner compressor seizure prevention device which does not cause the above problem by controlling the operation of the compressor based on these detected temperatures.

[0008]

According to the present invention, as a means for solving the above-mentioned problems, the invention described in claim 1 is characterized in that a temperature near a refrigerant discharge port of a compressor for compressing a refrigerant of an automotive air conditioner is provided. Using the temperature sensor for anti-freezing control provided at the outlet of the evaporator while attaching the sensor, when the detected temperature of both temperature sensors is input and the relationship between the two temperatures is set in advance, A control device for controlling the drive shaft of the compressor to be separated from the output shaft of the engine is provided.

According to a second aspect of the present invention, in the first aspect, the predetermined condition is such that a detection temperature of a temperature sensor attached to an evaporator is higher than a set value, and that It is characterized in that the state where the temperature detected by the attached temperature sensor is higher than the set value has continued for a predetermined time or more.

According to the above configuration, if the condition set in advance is set when the refrigerant leaks, the drive shaft of the compressor can be disconnected from the output shaft of the engine when the condition is satisfied. This reliably prevents seizure. By setting a certain frame for the temperature detected by both sensors as a condition, the drive of the compressor can be stopped only when the refrigerant leaks.

[0011]

FIG. 1 is a block diagram showing an embodiment of the present invention.
Will be described. 1 is a compressor temperature sensor, and 2 is an evaporator temperature sensor. The temperature sensor 1 is housed in an aluminum case like a conventional temperature switch, and this case is embedded in a hole provided in the compressor main body to detect the temperature of the compressor main body. The temperature sensor 2 conventionally uses the temperature sensor provided at the outlet of the evaporator as it is to prevent the freezing of the evaporator, and detects the air temperature at the outlet of the evaporator.

The two temperature sensors 1 and 2 are connected via amplifiers 3 and 4, respectively, to input terminals 5a and 5a of comparators 5 and 6, respectively.
6a. Other input terminals 5 of the comparators 5 and 6
The other ends of the variable resistors 8 and 9 having one end connected to a power supply positive line (12 volts of a vehicle-mounted power supply) 7 are connected to b and 6b. Reference numeral 10 denotes a ground circuit, which uses a vehicle body (not shown). The comparators 5 and 6 compare the voltage input through the amplifiers 3 and 4 with the set voltage set by the variable resistors 8 and 9, and output the output from the output terminals 5c and 6c when a condition described later is satisfied. It emits a signal.

Output terminals 5c and 6c of the comparators 5 and 6 are connected to input terminals 11a and 11b of the control device 11, respectively.
The control device 11 is provided with a control terminal 11c, and a contact 12 is provided between the control terminal 11c and the ground circuit 10.
a and an air conditioner switch 12 in which an indicator lamp 12b is connected in series. 11d is an output terminal of the control circuit 11. An electromagnetic clutch 13 is connected between the output terminal 11d and the ground circuit 10.
The electromagnetic clutch 13 is interposed between the output shaft of the engine and the drive shaft of the compressor (not shown). When the power is turned on, the electromagnetic clutch 13 connects them. When the power is cut off, the electromagnetic clutch 13 releases the connection and stops the compressor.

Next, the control operation will be described with reference to the flowchart of FIG. Contact 12a of air conditioner switch 12
By starting at step S1 by closing
In the next step 2, it is determined whether the temperature detected by the temperature sensor 2 attached to the outlet of the evaporator is lower or higher than 20 ° C. As a result, when the temperature is lower than 20 ° C., it is determined that the cooling device is functioning normally, and the process proceeds to step S3 to determine whether the temperature detected by the temperature sensor attached to the compressor is lower or higher than 135 ° C. .

As a result, when a temperature lower than 135 ° C. is detected, it is determined that the cooling is functioning normally without any abnormality, and in the next step S4, the control ends and the operation continues. When a temperature higher than 135 ° C. is detected, the energization of the electromagnetic clutch is cut off, and the operation of the compressor stops. Thereafter, when the temperature becomes 105 ° C. or lower, the operation is started again.

If it is determined in step S2 that the temperature detected by the temperature sensor 2 exceeds 20 ° C., the process proceeds to step S5, where it is determined whether the temperature of the compressor is 90 ° C. or less. As a result, when the temperature is 90 ° C. or lower, it is determined that the cooling function is not abnormal even if the air temperature at the evaporator outlet is high, and the operation of the compressor is continued.

When the temperature of the compressor is equal to or greater than 90 ° C. and the state is maintained for a certain period of time (about several minutes, but set appropriately), it is determined that an abnormal situation such as refrigerant leakage has occurred. Then, the operation of the compressor is stopped immediately by controlling the drive shaft of the compressor to be disconnected from the output shaft of the engine. When the compressor is stopped in such a process, the refrigerant cannot be reused unless a reset operation is performed after repairing the refrigerant leakage portion at a dealer or the like and replenishing the refrigerant. The indicator lamp 12b is turned on when the contact 12a is closed and operating normally, and turned off when the operation of the compressor is stopped. When the temperature of the compressor rises beyond the specified range, the controller receives an intermittent current from the control device 11 and blinks to notify the driver of the situation.

As the temperature sensor used in the embodiment described above, a thermistor capable of measuring accurately and quickly can be considered, but any other suitable one may be used. Further, each temperature value in the embodiment is merely an example, and it goes without saying that it varies depending on the characteristics of the vehicle, the capacity of the air conditioner, the type of the compressor, and the like.

[0019]

According to the first aspect of the present invention, both the temperature near the refrigerant discharge port of the compressor and the air temperature at the evaporator outlet are detected, and the relationship between the two temperatures is set in advance. In this case, the compressor drive shaft is controlled so as to be disconnected from the engine output shaft, so that the air temperature at the outlet of the evaporator is added to the operation control of the compressor, thus lowering the limit temperature of the compressor. Since it is not necessary to set the compressor, it is possible to reliably prevent the compressor from stopping during normal operation, which is rarely caused by the conventional compressor.

According to the second aspect of the present invention, since the specific conditions for operating the first aspect are determined, even if there is a variation in the temperature of the compressor during the operation, it is not affected. And good implementation can be achieved.

[Brief description of the drawings]

FIG. 1 is a circuit diagram according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a control operation of the apparatus of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Temperature sensor 2 Temperature sensor 5 Comparator 6 Comparator 11 Control device 12 Air conditioner switch 13 Electromagnetic clutch

Claims (2)

[Claims] 1. A temperature sensor is mounted in the vicinity of a refrigerant discharge port of a compressor for compressing refrigerant of an air conditioner for an automobile, and a temperature sensor for preventing freezing provided at an outlet of an evaporator is used to detect both temperature sensors. An air-conditioning compressor, comprising: a control device for controlling a drive shaft of the compressor to be disconnected from an output shaft of an engine when a temperature is input and a relationship between the two temperatures becomes a preset condition. Anti-seizure device. 2. The condition set in advance that the detected temperature of the temperature sensor attached to the evaporator is higher than the set value and the detected temperature of the temperature sensor attached to the compressor is higher than the set value for a predetermined time or more. The apparatus according to claim 1, wherein the burn-in prevention device for an air-conditioning compressor is provided.