JPS58210390A - Fault detector for compressor in car cooler - Google Patents

Abstract

PURPOSE:To reduce cost of the entire device by turning an electromagnetic clutch off when the difference between the output signals from means for detecting the rotation of a compressor and means for detecting the rotation of engine has exceeded over the setting level thereby eliminating a rotation sensor. CONSTITUTION:The signal VNC outputted from a compressor rotation detecting section 11 is amplified by an amplifier 13 to produce the signal VNC' which is provided to the input side of a differential amplifier 14 while the other input side is fed with the signal VNE corresponding to the engine rotation and the output from said amplifier 14 corresponds to the difference between both signals VNE and VNC' is fed to one input side of a comparator 16. When the compressor 1 fails to slip the belt thus to bring the difference of both signals VNC, VNC' above the setting level, the output of the comparator 16 goes high and fed to a timer 18 which produce L level signal over the setting time thus to break the electromagnetic clutch 2. With such structure, the rotation sensor is eliminated resulting in the cost reduction.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention is a compressor failure detection device for a vehicle cooling system, and in particular, a compressor failure detection device that detects a compressor failure based on the rotation speed of the compressor and the rotation speed of a drive source such as an engine that drives the compressor. This relates to a device that has been used.

A cooling device such as a refrigeration cycle for a refrigerated vehicle or a refrigeration cycle that controls the air conditioning inside the vehicle is composed of a compressor, etc., and this compressor is connected to a drive source such as a machine or engine via a belt or an electromagnetic clutch. It is operated by the driving force transmitted by the engine.

The compressor may become inoperable and stop due to insufficient lubrication of its sliding parts, a seizing accident, or damage to parts. If the compressor is operated in this condition, a large load will be placed on the drive source,
Not only will this damage the belt, etc., but the compressor may become unrepairable.

Therefore, a rotation sensor is attached to the compressor, and this rotation sensor detects the rotation speed of the compressor. When the rotation speed drops below the set value, the input to the electromagnetic clutch that drives the compressor is cut off, and the compressor is stopped. A device that is designed to stop is known.

However, if a rotation sensor is attached to a compressor in this way, a special device is required for attaching the rotation sensor.

Furthermore, since the cost of the rotation sensor is relatively high, the cost of the entire device is high.

Furthermore, if a hole is provided in the outer wall surface of the compressor to mount the rotation sensor, there is a risk of refrigerant leakage.

An object of the present invention is to detect the rotation speed of a compressor using a pressure sensor that detects the refrigerant pressure in a refrigeration cycle constituted by the compressor, and to control an electromagnetic clutch by comparing this detected value with the rotation speed of a drive source. In this way, the above-mentioned drawbacks are eliminated, and will be explained in detail below using examples.

1 and 2 are block diagrams showing an embodiment of a compressor failure detection device in a vehicle cooling system according to the present invention. In the figure, A is a vehicle cooling system, which is controlled by an electromagnetic clutch 2. It is composed of a compressor 1, a condenser 3, a liquid receiver 4, an expansion valve 5, and an evaporator 6. The evaporator 6 is housed, for example, in a duct 7 of an air conditioner, and is capable of cooling the introduced inside and outside air R. . A pressure sensor 10 for detecting the pressure number of the refrigerant is installed in the high-pressure side piping of the compressor 1, and as shown in FIG. 12. ,, the signal of the pressure sensor 10 is the compressor l
Contains a signal that pulsates in synchronization with the rotation of the The compressor rotation speed detection unit 11 outputs a signal VNC corresponding to the period of this pulsation signal.The output signal VNC increases as the compressor rotation speed NC increases, and this output signal vN
C is amplified by the amplifier 13 and supplied to one input side of the differential amplifier 14. Reference numeral 15 denotes an engine rotation speed detection section, which detects, for example, an output signal from an engine rotation speed meter, or an output signal from a tachogenerator provided on the rotating shaft of the engine or a rotating section linked thereto. The output signal VNE from the engine rotation speed detection section 15 increases as the engine rotation speed NH increases, and this output signal VNE is supplied to the other input side of the differential amplifier 14. In this case, the driving force of the engine is transmitted to the electromagnetic clutch 2 via a belt (not shown) or the like, and when the electromagnetic clutch 2 is excited, the driving force is transmitted to the compressor 1, and the compressor 1 is driven.

The predetermined engine speed NE when there is no failure in the compressor 1, when the belt is not slipping on the pulley provided on the electromagnetic clutch 2, and when there is no slippage in the electromagnetic clutch 2 itself. Output signal V at
Adjusting the amplifier 13 so that NE is equal to the output signal VNC at a predetermined rotational speed Nc of the compressor, and adjusting the gain of the output signal VNC,
It is assumed that settings are made in advance to obtain the above output signal VNC. The differential amplifier 14 outputs the signals VNE and VN.
calculates the difference with C, and its output is supplied to the comparator 16,
The comparator 16 compares the output signal from the amplifier 14 with a preset reference signal Vref. Reference signal V
ref.

As the output signal from the amplifier 14 increases, the output of the comparator 16 is inverted from L level to H level, and this signal is input to the timer 18 via the OR circuit 17. Since the timer 18 is composed of, for example, a monostable multipipe rake or a counter, it is reset based on the H and V bell output signals from the OR circuit 17, and outputs an L level output signal only for a set time T. This signal is supplied to the AND circuit 19. AND circuit 19
closes the gate for a period of time T during which this L level signal is input. Further, the output signal from the timer 18 is supplied to the input side of the counter 21.

The counter 21 counts the number of falling edges of the output signal of the timer 18, and when this count value reaches a set value, it outputs a signal to set the flip-flop 22 from the output terminal 21a, and the output of the flip-flop 22. terminal 22
The L level signal from a is supplied to the input side of the AND circuit 19. The AND circuit 19 is the flip-flop 22
When the output signal from the output terminal 22a, the output signal from the timer 18, and the output signal from the compressor control circuit 23 are all at H level, an H level signal is supplied to the electromagnetic clutch 2 to The clutch 2 is energized so that the driving force of the engine is transmitted to the compressor 1. The compressor control circuit 23 compares and calculates a set temperature signal from a temperature setting device provided on the control panel of the vehicle air conditioner and a vehicle interior temperature signal from an interior air sensor that detects the vehicle interior temperature. When the temperature is higher than the set temperature, an H level signal is outputted via the AND circuit 19 to excite the electromagnetic clutch 2. counter 21
, is reset by the rising or falling edge of the output signal of the compressor control circuit 23, and is also reset by turning on an air conditioner switch (not shown) that opens and closes the power supply of this device.

The flip-flop 22 is reset by turning on the air conditioner switch.

The discharge pressure detection section 12 detects the average value of the magnitude of the signal from the pressure sensor 10, and the signal from the discharge pressure detection section 12 is supplied to a comparator 24. Output signal and preset reference signal Vr
ef, and when the refrigerant pressure P exceeds the reference value, the comparator 24 outputs an H level signal, and this signal is input to the timer 18 via the OR circuit 17.

Next, the operation of the compressor failure detection device for a vehicle cooling system having the above configuration will be explained.

When the air conditioner switch shown in the figure is turned on, the counter 21 and flip-flop 22 are reset. Therefore, at this time, the output signal of the output terminal 22a of the flip-flop 22 is at H level, and the output signal of the timer 18 is at H level, which opens the gate of the AND circuit 19, so that the electromagnetic clutch 21 is controlled by the above control. circuit 23
controlled by the output signal from. That is, when the temperature inside the vehicle is higher than the set temperature, the output signal of the control circuit 23 becomes H level, so the electromagnetic flanch 2 is excited, and when the temperature inside the vehicle is lower than the set temperature, its output becomes L level. Since the level is increased, the electromagnetic clutch 2 is deenergized. When the electromagnetic clutch 2 is excited, the driving force of the engine is transmitted to the compressor 1, and the compressor 1 is operated.

As the compressor 1 rotates, a signal VNC proportional to the rotation speed is output from the compressor rotation speed detection section 11, and this signal VNC is amplified by the amplifier 13 and becomes vNC, which is connected to one input side of the differential amplifier 14. supplied to A signal VNE corresponding to the engine speed is supplied to the other input side of the differential amplifier 14, and the output of this amplifier 14 corresponds to the difference between the signals VNC and VNE, and this signal is used for comparison. is supplied to one input side of the device 16.

Here, when the compressor fails and the belt or the electromagnetic clutch 2 slips so that VNE-VN'C≧ref, the output of the comparator 16 reaches the H level. This signal is supplied to the OR circuit 17 and the timer 18, and the timer 18 starts timing operation at this point and outputs an L level signal for the set time T, which closes the gate of the CAND circuit 19. The input to the electromagnetic clutch 2 is cut off.

When the set time T has elapsed, the output signal of the timer 18 is
In order to restore the H level, the gate of the AND circuit 19 is opened and the electromagnetic clutch 2 is energized again. At this point, when the belt no longer slips, the counter 21 and the flip-flop 22 control the output signal of the compressor control circuit 23. It is reset at up or down. On the other hand, if the belt continues to slip, the comparator 16 outputs an H level signal again. Therefore, while the above-mentioned slip continues, the timer 18 outputs pulses that alternate between H level and L level, and the counter 21 counts these pulses, and when this count value reaches the set value, Since the set signal is supplied to the set input terminal of the flip-flop 22, the flip-flop 22 is thereby set, and the signal from the output terminal 22a is held inverted at the L level, and the AND circuit 19
gates will remain closed. Therefore, the operation of the compressor 1 is kept in a stopped state until the air conditioner switch is turned off.

Note that the counter 21 and flip-flop 22 are reset at the rising or falling edge of the output signal of the compressor control circuit 23, but in a state where the belt continues to slip as described above, the output signal of the compressor control circuit 23 Since the signal is normally maintained at H level, the counter 21 and flip-flop 22 are not reset by the output signal of the compressor control circuit 23.

Next, due to a failure such as clogging of the refrigeration cycle, the refrigerant pressure P
When T becomes higher than the set value, the output signal of the comparator 24 becomes H level, so the output of the timer 18 reaches the set time T.
The compressor 1 is temporarily stopped. If the refrigerant pressure P is higher than the set value even after the compressor 1 is temporarily stopped and driven again, the compressor is repeatedly stopped and driven, and this intermittent operation is detected by the counter 21.
When the set value of is reached, the compressor is launched to a standstill condition based on operations similar to those described above.

Next, the operation of the present invention when implemented by a digital computer such as a microcomputer will be explained with reference to the flowchart shown in FIG.

When the air conditioner switch is turned on, counters etc. are reset (step S1), data DNE for engine rotation eNE, data p for compressor rotation speed Nc.
Data Dp for NC and refrigerant pressure P is calculated (steps S2, S3, S4). Next, when there is no malfunction in the compressor 1 and the belt is slipping against the pulley provided on the electromagnetic clutch 2, and when the electromagnetic clutch 2 itself is not slipping, In order to perform gain adjustment so that the data DNE at the rotation speed NH and the data DNC at the predetermined rotation speed Nc of the compressor 1 at this time are equal, in step S5, the compressor rotation speed data DNC is multiplied by a predetermined value 2 for correction. Obtain data BNc. Step 56ffi calculates the degree of slip of the belt, and then calculates the difference between the engine speed data DNE and the corrected compressor speed data DNC in order to select the next operation. Selecting work.

In step S6, when the difference between the data DNE and DNC is less than the predetermined value a, that is, when it is determined that the belt slip has not reached the predetermined value, the process goes to step S7, and in step S7, the refrigerant pressure data Dp is compared with a predetermined value, and if it has not reached the predetermined value, the process returns to step S2 via step S8.

The above is a normal failure detection loop, and if there are no abnormalities, this loop is constantly monitored.

If it is determined in step S6t or step S7 that the belt slip is greater than or equal to the predetermined value, or that the refrigerant pressure is greater than or equal to the predetermined value, the process proceeds to step S9, and an off signal for the electromagnetic clutch 2 is activated in step S9. Output. Next, the process goes to steps S10, S11, and S12, which act as a timer to determine the time period during which the electromagnetic clutch 2 is turned off, and after a predetermined period of time has elapsed, the process proceeds to step S13 and then to step 8.
Go to 14. Note that CTR, , CTR in FIG. 3 indicate the counts of a first counter and a second counter (not shown). In step S13, the above step S6 is still /
Then, in step S7, the number of times the electromagnetic clutch 2 is turned off due to the abnormality detected is counted, and in step 814, it is determined whether the number of times is equal to or greater than a predetermined number of times d, and the next step is selected. If the above-mentioned number of times has not reached the predetermined number of times d, an ON signal for the electromagnetic clutch 2 is outputted in step S15, and the process returns to step S2. If the abnormality has been resolved at this point, the above-mentioned failure detection loop is repeated and the counter 2 is reset in step S8. Also,
If the abnormality continues, the operations from step S9 onwards are performed, and the above-mentioned judgment is made at step 814. If the predetermined number of times d has been reached here, go to step 816,
The loop stops by outputting an off signal for the electromagnetic clutch.

Therefore, in this case, the electromagnetic clutch 2 remains off unless the air conditioner switch is turned off and turned on again. Therefore, the driver of the vehicle has time to detect the abnormality and take corrective action.

As explained above, according to the failure detection device for a compressor of a single-vehicle cooling system according to the present invention, the rotation speed of the compressor can be substantially detected using a pressure sensor. No special equipment is required for installation, the structure can be simplified and costs can be reduced, and the risk of refrigerant leakage due to holes in the outer wall of the compressor is eliminated. can do. Furthermore, the pressure sensor can be installed anywhere as long as the refrigerant pressure fluctuates in accordance with the rotation of the compressor during the cycle of the vehicle cooling system A. Therefore, the tolerance for installing the pressure sensor can be increased and maintenance can be improved. It is also advantageous from the point of view.

Furthermore, according to the present invention, if the condition where the belt slips continues, the compressor is launched to a completely stopped state, and if the belt slips for only a short time, the set time T is started even if the compressor is stopped. It will be operated again after the period has elapsed. Therefore, even if a slight time slip occurs, for example, when the engine speed suddenly increases from an idling state or when suddenly accelerating, the compressor will not be latched to a stopped state. Malfunctions can be prevented.

Although the present invention has been described as being applied to a cooling device constituting an air conditioner, the present invention is not limited thereto, and the present invention can be similarly applied to a cold leg device constituting a refrigeration cycle of a refrigerated vehicle. Of course.

As explained above, according to the failure detection device for a compressor of a vehicle cooling system according to the present invention, a pressure sensor that detects the pressure of refrigerant in a cooling system including a compressor;
A compressor rotation speed detection means for detecting the rotation speed of the compressor based on the output signal of the pressure sensor, an engine rotation speed detection means, an output signal 2 of the compressor rotation speed detection means and an output signal from the engine rotation speed detection means. and a set value, and turns off the electromagnetic clutch when the difference between the two signals becomes larger than the set value. This makes it possible to reduce the cost of the entire device and prevent risks such as refrigerant leakage.

[Brief explanation of the drawing]

1 and 2 are block diagrams showing one embodiment of a compressor failure detection device in a vehicle cooling system according to the present invention, and FIG. 3 is a block diagram showing an example of a compressor failure detection device according to the present invention configured with a microcomputer. It is a flowchart for explaining operation. 1...Compressor? ...Electromagnetic clutch, 10.
...Pressure sensor, 11...Compressor rotation speed detection section, 12...Discharge pressure detection section, 14...Differential amplifier,
15... Engine rotation speed detection section, 18... Timer,
21...Counter, 22...Flip-flop, 2
3...Compressor control circuit. Patent applicant: Agent of Diesel Kiki Co., Ltd.
Patent attorney Jun Miyazono −

Claims (2)

[Claims] (1) A pressure sensor that detects the pressure of refrigerant in a cooling device including a compressor, a compressor rotation speed detection means that detects the rotation speed of the compressor based on the output signal of this pressure sensor, and rotation of the imprenosa drive source. and a comparison control that outputs a signal to stop the compressor for a predetermined time when the difference between the output signal from the compressor rotation speed detection means and the output signal of the compressor drive source rotation speed detection means becomes larger than a set value. What is claimed is: 1. A failure detection device for a compressor in a vehicle cooling system, characterized by comprising: means. (2) A pressure sensor that detects the pressure of refrigerant in a cooling device including a compressor, a compressor rotation speed detection means that detects the rotation speed of the compressor based on the output signal of the pressure sensor, and a rotation speed of the drive source of the compressor. a detection means, and a comparison control means for outputting a signal to stop the compressor for a predetermined time when the difference between the output signal from the compressor rotation speed detection means and the output signal of the compressor drive source rotation speed detection means becomes larger than a set value. and a count control means that counts each time the stop signal for stopping the compressor compressor is released by the comparison control means and holds the compressor in a stopped state when this count value reaches a set value. 1. A failure detection device for a compressor in a vehicle cooling system, characterized by the following.