JPH06293213A - Refrigerating cycle compressor operation monitoring device - Google Patents

Abstract

PURPOSE:To judge locking accurately even when high-pressure side pressure is lowered due to the lowering of heat load, etc., by providing a means for obtaining a variation rate of detected high-pressure side pressure to judge locking when the variation rate exceeds a specified judgment reference value. CONSTITUTION:After the output voltage from a high-pressure side pressure sensor 34 is rectified in waveform by eliminating noise components, it is inputted into a microcomputer in a compressor control circuit 33 for operating and stopping a compressor 16 by signals from an air conditioner control circuit 28, and a specified program is run to obtain the variation rate of the high- pressure side pressure. When this variation rate exceeds a specified lock judgment reference value, the compressor 16 is judged to be locked, and an electromagnetic clutch 27 is turned off through a drive circuit to stop the driving of the compressor 16. Thus, even when the high-pressure side pressure is lowered due to lowering of heat load, small leakage of refrigerant, etc., the locking of the compressor 16 can be judged accurately and, at locking, the driving can be stopped to prevent a drive system from being damaged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refrigeration cycle compressor operation monitoring device having a function of detecting whether or not a compressor is in a locked state.

[0002]

2. Description of the Related Art For example, a compressor operation monitoring device disclosed in Japanese Patent Laid-Open No. 4-177072 is provided with a high pressure side pressure sensor for detecting the high pressure side pressure of a refrigeration cycle, and an output voltage Vp of the high pressure side pressure sensor is provided. Is compared with a predetermined lock determination reference voltage Vpo, and when Vp <Vpo, it is determined that the compressor is in the locked state.

[0003]

By the way, when the heat load fluctuates during operation of the compressor due to, for example, turning on / off of the heat radiation fan, change of the capacity of the compressor, fluctuation of the engine speed, and so on, FIG. As shown in
The output voltage Vp (high pressure side pressure) of the high pressure side pressure sensor fluctuates greatly, and as the heat load decreases, the output voltage Vp (high pressure side pressure) of the high pressure side pressure sensor also decreases. Therefore, in the above-described conventional configuration, when the heat load becomes small, the output voltage Vp of the high-pressure side pressure sensor becomes lower than the predetermined lock determination reference voltage Vpo, although the compressor is not locked. Therefore, there is a possibility that the compressor lock may be erroneously determined.

In the above-mentioned conventional structure, in order to prevent erroneous determination that the pressure drop on the high-pressure side due to "refrigerant leakage" is the lock of the compressor, the pipe on the downstream side of the receiver (in the normal state, the refrigerant is A flow sensor is provided in the pipe (flowing in the liquid phase state), and the gas phase component in the refrigerant is detected by this flow sensor to discriminate between lock of the compressor and "refrigerant leakage". It is only a solution to the misjudgment due to "refrigerant leakage",
It goes without saying that the erroneous determination due to "reduction of heat load" has not been solved at all.

The present invention has been made in view of such circumstances, and an object thereof is to accurately determine lock of the compressor even when the pressure on the high-pressure side is decreased due to a decrease in heat load or the like. It is to provide a compressor operation monitoring device for a refrigeration cycle.

[0006]

In order to achieve the above object, a compressor operation monitoring device for a refrigerating cycle according to the present invention comprises a high pressure side pressure detecting means for detecting the high pressure side pressure of the refrigerating cycle, and the high pressure side pressure detecting means. Pressure change rate determining means for obtaining the change rate of the high pressure side pressure detected by the means, and the compressor when the change rate of the high pressure side pressure obtained by the pressure change rate determining means exceeds a predetermined lock determination reference value. The lock determination means for determining the lock is used.

In this case, the lock determining means may include a lock-time stopping means for stopping the driving of the compressor when the lock determining means determines that the compressor is locked.

[0008]

According to the results of experiments by the present inventor, as shown in FIG. 4, when the compressor is not locked, the rate of change of the high-pressure side is small and almost constant even when the high-pressure side changes. However, it has been found that when the compressor locks up, the rate of change of the high-pressure side pressure increases significantly regardless of whether the high-pressure side pressure is high or low. The present invention determines the lock of the compressor as follows by utilizing the magnitude relation of the change rate of the high pressure side pressure. First, the high pressure side pressure of the refrigeration cycle is detected by the high pressure side pressure detection means, and the change rate of the detected high pressure side pressure is obtained by the pressure change rate determination means. Then, the change rate of the high pressure side pressure is compared with a predetermined lock determination reference value by the lock determination means, and when the change rate of the high pressure side pressure exceeds the lock determination reference value, it is determined that the compressor is locked. As described above, when the compressor is locked, the change rate of the high-pressure side becomes significantly large even when the high-pressure side pressure drops, so if the lock of the compressor is determined by the change rate of the high-pressure side pressure as in the present invention, Even when the pressure on the high-pressure side decreases due to a decrease in heat load or some refrigerant leakage, it is possible to accurately determine the lock of the compressor.

Further, when the lock determining means determines that the compressor is locked, the drive means of the compressor is stopped by the lock-time stopping means to prevent damage to the drive system of the compressor.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to an automobile air conditioner will be described below with reference to the drawings. A blower 13 is arranged on the intake port 12 side in the blower duct 11, and an evaporator 15 which is a component of the refrigeration cycle 14 is arranged on the downstream side of the blower 13. In the refrigeration cycle 14, the refrigerant discharged from the discharge port 16a of the compressor 16 is condensed into a condenser 17, a receiver 18, an expansion valve 19, and a refrigerant.
The evaporator 15 is circulated in the order of the intake port 16b of the compressor 16, and the air blown by the blower 13 is cooled and dehumidified by the evaporator 15. In addition, the opening degree of the expansion valve 19 supplies an appropriate amount of refrigerant to the evaporator 15 according to the fluctuation of the cooling / dehumidifying load (heat load) by the temperature sensing cylinder 20 that detects the refrigerant temperature on the outlet side of the evaporator 15. Is automatically adjusted.

On the other hand, on the downstream side of the evaporator 15, an air mix damper 21 and a heater core 23 for circulating hot water for cooling the engine 22 for running the vehicle are arranged, and the opening degree of the air mix damper 21 is controlled by a servo motor 24. The mixing ratio of the air passing through the heater core 23 and the air not passing through the heater core 23 is adjusted by adjusting the
Adjust the temperature of the air blown from. In addition, compressor 1
6 uses a vehicle traveling engine 22 as a drive source, and its driving force is transmitted via a belt transmission mechanism 26 and an electromagnetic clutch 27.

The above-described motor 13a of the blower 13 and the servomotor 24 of the air mix damper 21 are controlled by an air conditioning control circuit 28. In this air conditioning control circuit 28,
A set temperature signal is input from the temperature setting switch 29, and an outside air temperature sensor 30 that detects an air temperature outside the vehicle compartment, an inside air temperature sensor 31 that detects an air temperature inside the vehicle compartment, and an insolation amount are detected in order to determine an environmental condition. Detection signals are input from various sensors such as the solar radiation sensor 32.

On the other hand, the electromagnetic clutch 2 of the compressor 16
7 is controlled by the compressor control circuit 33.
The compressor control circuit 33 turns on / off the electromagnetic clutch 27 and operates / stops the compressor 16 in response to a compressor operation / stop signal input from the air conditioning control circuit 28. The compressor control circuit 33 and the high pressure side pressure sensor 34 which is the high pressure side pressure detecting means for detecting the high pressure side pressure Pn of the refrigeration cycle 14 constitute a compressor operation monitoring device 35. A voltage signal corresponding to Pn is input to the compressor control circuit 33. In the present embodiment, the high pressure side pressure sensor 34 is constituted by, for example, a semiconductor pressure sensor, and the condenser 17 in the high pressure side pipe of the refrigeration cycle 14 is
It is attached to the pipe wall of the pipe 36 that connects the receiver 18 with the receiver 18 by screwing or the like.

The compressor control circuit 33, in detail, as shown in FIG. 2, has a filter 37 and a waveform shaping circuit 3.
8, a microcomputer 39 and a drive circuit 40. As a result, the output voltage Vp of the high-pressure side pressure sensor 34 is filtered by the filter 37 to remove the high-frequency component that is a noise component, and the waveform is shaped by the waveform shaping circuit 38 to obtain the signal of the high-pressure side pressure Pn as the signal of the microcomputer 3.
9 is input. This microcomputer 39 functions as a pressure change rate determination means for obtaining the change rate of the high pressure side pressure Pn by executing the control program shown in FIG. 3 stored in a built-in ROM (not shown), and It functions as lock determining means for determining that the compressor 16 is locked when the rate of change of the high-pressure side pressure Pn exceeds a predetermined lock determination reference value α, and when the compressor 16 is locked, the electromagnetic clutch is provided via the drive circuit 40. Two
It also functions as a lock-time stop means for turning off 7 to stop driving of the compressor 16.

The lock determination method of the compressor 16 by the microcomputer 39 will be described below with reference to the flowchart of FIG. First, in step 101, after initialization processing, in step 102, the air conditioning control circuit 28
It is determined whether or not the compressor operation signal is output, and if "NO", the electromagnetic clutch 27 is maintained in the off state (step 110), and the operation waits until the compressor operation signal is output.

Thereafter, when the compressor operation signal is output, the routine proceeds from step 102 to step 103, the electromagnetic clutch 27 is turned on, the driving force of the engine 24 is transmitted to the compressor 16, and the operation of the compressor 16 is started. Start. Next, in step 104, the output voltage Vp (high pressure side pressure Pn) of the high pressure side pressure sensor 34 is converted into a digital value by a built-in A / D converter (not shown) and read, for example, every one second. A change amount ΔPn of the high pressure side pressure Pn from the previous sampling is calculated by the following equation (1) (step 105). ΔPn = Pn-1 -Pn (1) Here, Pn-1 is the high pressure side pressure at the time of the previous sampling, and the sampling cycle is, for example, 1 second.

Thereafter, at step 106, the high pressure side pressure P
The change rate of n is calculated by the following equation (2). Change rate of high-pressure side pressure Pn = ΔPn / Pn-1 (2) In this way, change rate of high-pressure side pressure Pn ΔPn / Pn-
After calculating 1, the process proceeds to step 107, and this change rate ΔPn / Pn-1 is compared with a predetermined lock determination reference value α,
When the rate of change ΔPn / Pn-1 exceeds the lock determination reference value α, it is determined that the compressor 16 is locked. In this embodiment, the lock determination reference value α is set to, for example, 0.05, and the reason is as follows.

That is, according to the experimental results of the present inventor, during operation of the compressor 16, for example, turning on / off of a heat radiating fan (not shown), change in capacity of the compressor 16, change in rotational speed of the engine 22, etc. As shown in FIG. 6, due to fluctuations in heat load and some refrigerant leakage, the high pressure side pressure P
Although n changes, the change is relatively slow. Therefore, as shown in FIG. 4, when the compressor 16 is not locked, the high pressure Pn changes even if the high pressure Pn changes. The ratio ΔPn / Pn-1 is 0.0
It becomes almost constant at about 1. On the other hand, the compressor 1
When 6 is locked, the high-pressure side pressure Pn drops sharply as shown in FIG. 5, and therefore, as shown in FIG.
Get bigger. Focusing on this characteristic, in the present embodiment,
The lock determination reference value α is set to 0.05.

In step 107 described above, "YES",
That is, when it is determined that the compressor 16 is locked,
In step 109, the electromagnetic clutch 27 is turned off, and the driving of the compressor 16 by the engine 24 is stopped. At the same time, this program is stopped, and thereafter, it waits in this state until it is reset.

On the other hand, the change rate ΔPn / P of the high-pressure side pressure Pn
When n-1 is equal to or smaller than the lock judgment reference value α, step 1
It is judged "NO" in 08, that is, it is judged that the compressor 16 is not locked, and the routine proceeds to step 109, where the high pressure side pressure Pn is the upper limit value β of the proper pressure (for example, 21 kgf / cm 2
G) It is determined whether or not the above. If the determination in step 109 is "YES", that is, if Pn ≥β, the high-pressure side pressure Pn is abnormally high, so the routine proceeds to step 110, where the electromagnetic clutch 27 is turned off and the compressor 16
To keep the refrigeration cycle 14 safe. On the other hand, if "NO" in step 109, that is, Pn <β, the high-pressure side pressure Pn is within the normal pressure range, and therefore the compressor 16 is not stopped and the process returns to step 102 to lock the compressor 16 described above. Processing such as determination is repeatedly executed.

According to the present embodiment described above, when the compressor 16 is locked, the rate of change ΔPn / Pn-1 of the high-pressure side pressure Pn remarkably increases irrespective of whether the high-pressure side pressure Pn is high or low. , The rate of change ΔPn / Pn-1 of the high-pressure side pressure Pn detected by the high-pressure side pressure sensor 34 is calculated,
When the rate of change ΔPn / Pn-1 exceeds the lock determination reference value α, it is determined that the compressor 16 is locked. Therefore, when the high pressure side pressure Pn decreases due to a decrease in heat load or some refrigerant leakage. However, the lock of the compressor 16 can be accurately determined. Moreover, it is not necessary to use a conventional flow sensor (refrigerant leakage detection means) together for the lock determination of the compressor 16, and accordingly,
The configuration can be simplified and the price can be reduced.

When it is determined that the compressor 16 is locked, the electromagnetic clutch 27 is turned off to stop the driving of the compressor 16, so that the drive system of the compressor 16 can be prevented from being damaged. Needless to say, a warning means may be provided to display or sound when it is determined that the compressor 16 is locked.

By the way, in this embodiment, the capacitor 17
The high pressure side pressure sensor 34 is attached to the pipe 36 connecting the receiver 18 and the receiver 18, but the high pressure side refrigerant flow path of the refrigeration cycle 14 (that is, the discharge port 16a of the compressor 16).
From the expansion valve 19 to the refrigerant flow path), the high pressure side pressure can be detected at any position. Therefore, for example, a high pressure side pressure sensor is attached to the discharge pipe 41 of the compressor 16, or the receiver 18 and the expansion valve 19 are connected. It is also conceivable to attach a high pressure side pressure sensor to the pipe 42 connecting the above.

However, when the high pressure side pressure sensor is attached to the discharge pipe 41 of the compressor 16, the detected high pressure side pressure is strongly influenced by the discharge pulsation pressure of the compressor 16 and pulsates, and the pulsating component is generated. It is necessary to remove the detection signal. On the other hand, the receiver 18
When a high-pressure side pressure sensor is attached to the pipe 42 connecting the expansion valve 19 and the expansion valve 19, it is not affected by the discharge pulsation pressure of the compressor 16, but even when the compressor 16 is locked, immediately after the lock, Since the liquid refrigerant in the receiver 18 leaks out for a while, the decrease in the high-pressure side pressure detected immediately after locking may be moderate, and the lock determination may be delayed a little.

In this respect, according to this embodiment, the capacitor 1
Since the high pressure side pressure sensor 34 is attached to the pipe 36 connecting the 7 and the receiver 18, the high pressure side pressure to be detected is not affected by the discharge pulsation pressure of the compressor 16,
In addition to enabling stable pressure detection, there is no need to be affected by liquid leakage from the receiver 18, and lock determination can be made quickly without delay. However, the present invention is not limited to this, and the mounting position of the high-pressure side pressure sensor (high-pressure side pressure detecting means) is set to the discharge pipe 41 of the compressor 16.
Or the pipe 42 downstream of the receiver 18 or the condenser 1
7 and the receiver 18 may be changed, and even in this case, the intended purpose of the present invention can be sufficiently achieved.

The present invention is not limited to the air conditioner for automobiles as in this embodiment, and may be, for example, a refrigerator for automobiles, a house,
It can be widely applied to and implemented in devices that incorporate a refrigeration cycle, such as building air conditioners and refrigerators. Further, in this embodiment, the driving force of the driving source (engine 22) is applied to the electromagnetic clutch 2
Although the power is transmitted to the compressor 16 via a power transmission means such as 7, the output shaft of the drive source (motor or engine dedicated to the refrigeration cycle) may be directly connected to the rotary shaft of the compressor 16. In this case, The drive source may be stopped when the compressor is locked.

Further, in the present embodiment, the respective means of the present invention are realized by the software incorporated in the microcomputer 39, but these respective means may be constituted by analog circuits (hardware). Further, in this embodiment,
Although the compressor control circuit 33 is provided separately from the air conditioning control circuit 28, these may be integrated so that the processing performed by the compressor control circuit 33 is performed in the air conditioning control circuit 28.

In addition, the present invention is based on the high pressure side pressure sensor 34.
As the (high pressure side pressure detecting means), other pressure sensors such as a strain gauge type pressure sensor may be used instead of the semiconductor pressure sensor, and the sampling period of the high pressure side pressure and the lock determination reference value α are also used. Various modifications can be made without departing from the spirit of the invention, such as appropriate modification according to the characteristics of the refrigeration cycle.

[0029]

As is apparent from the above description, according to the present invention, the rate of change of the high-pressure side pressure is obtained, and when the rate of change exceeds the lock determination reference value, it is determined that the compressor is locked. Therefore, even when the high-pressure side pressure is reduced due to a decrease in heat load or some refrigerant leakage, it is possible to accurately determine the lock of the compressor. Moreover, it is not necessary to use a conventional flow sensor (refrigerant leakage detection means) together for the lock determination of the compressor.

Further, when it is determined that the compressor is locked, the driving of the compressor is stopped, so that there is an advantage that damage to the drive system of the compressor can be prevented.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of an entire apparatus showing an embodiment of the present invention.

FIG. 2 is a block diagram of a compressor control circuit.

FIG. 3 is a flowchart showing a control flow.

FIG. 4 is a graph of experimental data showing the relationship between the pressure on the high pressure side and the rate of change ΔPn / Pn-1.

FIG. 5 is a graph showing changes in the high-pressure side pressure when the compressor is locked.

FIG. 6 is a graph showing changes in high-pressure side pressure during operation of the compressor.

[Explanation of symbols]

14 ... Refrigeration cycle, 15 ... Evaporator, 16 ... Compressor, 17 ... Condenser, 18 ... Receiver, 19 ...
Expansion valve, 22 ... Engine, 23 ... Heater core, 26 ... Belt transmission mechanism, 27 ... Electromagnetic clutch, 28 ... Air conditioning control circuit, 33 ... Compressor control circuit, 34 ... High pressure side pressure sensor (high pressure side pressure detecting means), 35 ... Compressor operation monitoring device, 39 ... Microcomputer (pressure change rate determination means, lock determination means, lock time stop means).

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroshi Kinoshita 1-1 Showa-cho, Kariya city, Aichi Prefecture Nihon Denso Co., Ltd. (72) Inventor Shin Nishida 1-1-chome Showa town, Kariya city, Aichi prefecture Nidec Within the corporation

Claims (2)

[Claims] 1. A high pressure side pressure detection means for detecting a high pressure side pressure of the refrigeration cycle, comprising: a high pressure side pressure detection means for monitoring the operating state of a compressor for discharging a refrigerant to circulate in the refrigeration cycle. A pressure change rate determination means for obtaining the detected change rate of the high pressure side pressure, and the lock of the compressor when the change rate of the high pressure side pressure obtained by the pressure change rate determination means exceeds a predetermined lock determination reference value. A compressor operation monitoring device for a refrigeration cycle, comprising: a lock determining means for determining. 2. The compressor operation monitoring of the refrigeration cycle according to claim 1, further comprising lock-time stop means for stopping the drive of the compressor when the lock determination means determines that the compressor is locked. apparatus.