JPH0241441B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a means for preventing slippage of an electromagnetic clutch of a compressor in an automotive air conditioner.

A compressor in an automobile air conditioner receives driving force from the engine via a belt transmission device and an electromagnetic clutch, and uses this driving force to compress refrigerant gas. The electromagnetic clutch is powered by a power source consisting of a battery and a generator. Therefore, when the voltage supplied to the electromagnetic clutch from the power supply source decreases, for example when the battery is not sufficiently charged and the electromagnetic clutch is idling, the electromagnetic clutch loses power between the rotating body on the drive source side and the driven source. Slippage may occur with the side rotating body, causing seizure due to the heat generated by both rotating bodies, and at the same time, the heat is transmitted to the belt transmission device, causing the V-belt of the belt transmission device to burn out, causing a serious accident. . Therefore, conventionally, as shown in Japanese Patent Application Laid-Open No. 55-100430, a speed detector is provided to detect the respective speeds of the two rotating bodies, and the speeds of the two are compared to determine the speed difference. The system detects slippage based on the occurrence of slippage, and when slippage occurs, power to the electromagnetic clutch is turned off to stop driving the compressor.

However, if actual slippage is detected and the energization of the electromagnetic clutch is controlled on/off, the detection of slippage may be delayed and a large amount of heat may have already been generated by the time slippage is detected, resulting in the above-mentioned seizure and other accidents. There was a possibility of it happening.

SUMMARY OF THE INVENTION An object of the present invention is to provide a means for preventing the electromagnetic clutch of a compressor from slipping, and a configuration for achieving this object is shown in FIG. That is, in FIG. 1, the voltage Ec applied to the electromagnetic clutch 10 of the compressor 4 is detected by the voltage detector 18,
The voltage level determining means 23 determines whether the voltage belongs to one of at least three levels: high, medium, and low. Additionally, a discharge pressure detector 24 detects the discharge pressure Pd of the compressor 4 as needed, and when the voltage level determination means 23 determines that the voltage Ec is at an intermediate level, the discharge pressure detector 24 detects the discharge pressure Pd. Discharge pressure level determining means 25 is provided for determining which of at least three levels high, medium, and low the discharge pressure Pd belongs to. and,
Depending on the determination result of the voltage level determination means 23 (including the discharge pressure level determination means 25 if necessary), the electromagnetic clutch 10 of the compressor 4 and the blower having the same power supply source 13 as the electromagnetic clutch 10 are determined. The control means 1 controls the energization of the motor 2a of
7.

Therefore, the electromagnetic clutch 10 of the compressor 4
The conditions for the slip are as shown in Figure 2.
Range where slippage occurs due to the relationship between Ec and discharge Pd
(a), range where slipping occurs depending on other conditions such as engine speed (b), and range where slipping does not occur (c)
They are divided into curves S ₁ and S ₂ , respectively. Therefore, under normal conditions where the discharge pressure Pd is P1 _or less, it is safe when the level of the voltage Ec determined by the voltage level determining means 23 is at a high level of Ec≧ _E1 . When the level is at a medium level (E ₁ > Ec ≧ E ₂₎ , it can be regarded as a caution level, and when it is at a low level, Ec < E ₂ , it can be regarded as a dangerous level. If the power supply to the motor 2a of the motor 2 is reduced, the power consumption of the power supply source 13 may be reduced and the power consumption may be recovered.
There is no slippage, and therefore the above object can be achieved. However, if there is a possibility that the discharge pressure Pd of the compressor 4 will exceed _P1 , such as when the air conditioner is not equipped with a high-pressure cut switch, etc., it is necessary to correct each boundary, and the voltage Ec Even if the discharge pressure level is at the caution level, the discharge pressure Pd is determined by the discharge pressure level determination means 25.
It is designed to determine the level of and satisfy the need.

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 3, an embodiment of the invention is shown,
In the automotive air conditioner, inside air or outside air is sucked in by a blower 2 from the most upstream side of an air conditioning case 1, and an evaporator 3 is provided on the downstream side of the blower 2.

The evaporator 3 constitutes a cooling cycle together with a compressor 4, a condenser 5, a liquid tank 6, and an expansion valve 7. The compressor 5 receives the rotational force of the engine 9 together with the generator 8 via the belt transmission device 26, and
The drive is stopped by turning on and off the electromagnetic clutch 10 of the compressor 5.

The positive terminal of the generator 8 is connected to the voltage regulator 11
is connected to the positive terminal of battery 12 via
The generator 8 and the battery 12 constitute a power supply source 13 shown in FIG. I'm starting to do that. Electromagnetic clutch drive circuit 14
The blower drive circuit 15 is a known device that combines relays and transistors, and together with the microcomputer 16 described below, constitutes the control means 17 shown in FIG. energization to the electromagnetic clutch 10 is controlled on and off, or energization to the motor 2a of the blower 2 is controlled in stages.

The microcomputer 16 is a central processing unit.
CPU, memorize program procedures and fixed data
It is equipped with a ROM, a memory RAM that can read and write data, and an input/output device I/O. This microcomputer 16 receives analog signals from a voltage detector 18 that detects the voltage Ec supplied to the electromagnetic clutch 10, a temperature setting device 19 that sets the vehicle interior temperature, and a heat load detector 20 that detects the heat load. selected by the multiplexer 21, and further A/D
The signal is converted into a digital signal and input via the converter 22. The heat load detector 20 includes an in-vehicle sensor that detects the cabin temperature, an outside air sensor that detects the outside air temperature, a solar radiation sensor that detects the amount of solar radiation, an evaporator sensor that detects the fin temperature of the evaporator 3, and the like. Note that the voltage detector 18 is
In this embodiment, the power supply voltage is detected, but in other embodiments, the electromagnetic clutch 1
A terminal voltage of 0 may be detected.

In FIG. 4, the microcomputer 1
6 control operation examples are shown as a flowchart,
When the power is turned on, the microcomputer 16 starts executing the program from a start step 30, and in the next step 31 reads voltage Ec data from the voltage detector 18.
Proceed to the next step 32.

In step 32, the voltage Ec is compared to see if it is larger than predetermined values E ₁ and E ₂ stored in advance in the memory ROM, and Ec≧E ₁ , E ₁ >Ec≧E ₂ ,
The voltage level determining means 23 shown in FIG. 1 is constituted by step 32, which determines which of the three levels represented by Ec< _E2 it belongs to.

If it is determined in step 32 that Ec≧E ₁ , it can be considered that the electromagnetic clutch 10 is at a safe level where sufficient power is supplied and no slipping occurs, so the next steps 33 and 34 are performed.
Then, data is read from the temperature setting device 19 and thermal load detector 20, and from this data a control signal is calculated so as to approach the set temperature, and normal control is performed to output it to the electromagnetic clutch drive circuit 14 and blower drive circuit 15. . Also, in step 32, E ₁ >
If it is determined that Ec≧E ₂ , the electromagnetic clutch 10 is not supplied with much power, and this can be considered as a caution level that may drop to the extent that slippage may occur in the future. Normal control is performed on the fan 2, but the fan 2 is fixed at a low rotation speed unless it is originally at a low rotation speed or has been stopped, thereby reducing power consumption and restoring the power of the power supply source 13. I will pray for you. Further, if it is determined in step 32 that Ec<E ₂ , it can be regarded as a dangerous level that may cause the electromagnetic clutch 10 to slip, so the process proceeds to steps 37 and 38, and the compressor 4
Then, the drive of the blower 2 is stopped to prevent the electromagnetic clutch 10 from slipping. Incidentally, when the processing of steps 34, 36, and 38 is completed, the processing of step 31 is completed again.
Return to

In FIG. 5, another embodiment of the present invention is shown, which differs from the previous embodiment in that the discharge pressure of the compressor 4 is applied to the input element to the microcomputer 16. That is, a discharge pressure detector 24 for detecting the pressure of refrigerant gas is provided on the discharge side of the compressor 4, and the discharge pressure Pd detected from the discharge pressure detector 24 is sent to the multiplexer 21 and the A/D.
The signal is input to the microcomputer 16 as a digital signal via the converter 22. Note that this discharge pressure detector 24 may be replaced by a heat-sensitive element such as a thermistor. As shown in FIG. 6, steps 39 and 40 are inserted between step 32 and step 35 of the program in the above embodiment. In step 39, the discharge pressure Pd data from the discharge pressure detector 24 is read.
In the next step 40, the discharge pressure Pd is compared to see if it is larger than predetermined values P ₁ and P ₂ stored in advance in the memory ROM, and Pd≧P ₁ , P ₁ >Pd≧
It is determined which of the three levels shown by P ₂ and Pd<P ₂ the discharge pressure level belongs to, and step 40 constitutes the discharge pressure level determining means 25 shown in FIG. This is because even if the voltage Ec is E ₁ >Ec≧E ₂ in step 32, the conditions that cause the electromagnetic clutch 10 to slip differ depending on the magnitude of the discharge pressure Pd, so it is determined in step 40 that Pd<P ₂ . If it is, it is at the safe level, so step 33
If it is determined that P ₁ > Pd ≧ P ₂ , it is at the caution level and the process proceeds to step 35, and if Pd ≧ P ₁ is determined that it is at the dangerous level, the process proceeds to step 37. .

In the above two embodiments, the rotation of the blower 2 is controlled to be low when the warning level is reached. motor 2
Any control method that suppresses the normal control to a can be adopted.

As described above, according to the present invention, when the voltage applied to the electromagnetic clutch of the compressor decreases, the energization of the electromagnetic clutch and the blower motor is controlled, thereby preventing the electromagnetic clutch from slipping. It can be prevented. Furthermore, since it is easier to detect voltage and discharge pressure than to detect rotational speed, the overall structure of the apparatus is simplified and costs can be reduced.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of an automotive air conditioner according to the present invention, FIG. 2 is a characteristic diagram showing the conditions that cause slippage in the electromagnetic clutch, FIG. 3 is a configuration diagram showing an embodiment of the present invention, and FIG. The figure is a flowchart showing an example of the control operation of the microcomputer used in the above, FIG. 5 is a block diagram showing another embodiment of the present invention, and FIG. It is a flowchart diagram. 2...Blower, 2a...Motor, 4...Compressor, 10...Electromagnetic clutch, 13...Power supply source, 1
7... Control means, 18... Voltage detector, 23... Voltage level determination means, 24... Discharge pressure detector, 25... Discharge pressure level determination means.

Claims (1)

[Claims] 1. A voltage detector that detects the voltage applied to the electromagnetic clutch of the compressor, and a voltage detector that determines whether the voltage detected by the voltage detector belongs to at least three levels: high, medium, and low. and a control means for controlling energization to an electromagnetic clutch of the compressor and a motor of a blower having the same power supply source as the electromagnetic clutch, in accordance with the judgment result of the voltage level judgment means. An automotive air conditioner characterized by: 2. A voltage detector that detects the voltage applied to the electromagnetic clutch of the compressor, and voltage level determining means that determines which of at least three levels, high, medium, and low, the voltage detected by this voltage detector belongs to. and a discharge pressure detector for detecting the discharge pressure of the compressor; and when the voltage level determining means determines that the voltage belongs to an intermediate level, the discharge pressure detected by the discharge pressure detector is set to a high level.
discharge pressure level determining means for determining which of at least three levels medium and low it belongs to, and an electromagnetic clutch of the compressor according to the determination results of the voltage level determining means and the discharge pressure level determining means, and the same as the electromagnetic clutch. An air conditioner for an automobile, comprising: control means for controlling energization of a motor of a blower having a power supply source.