JPS5871214A - Automobile's cooler - Google Patents

Abstract

PURPOSE:To prevent both a secondary failure and a misjudgement caused by ignition noise or other reasons in a car room air conditioning cooler by disengaging a solenoid clutch when the specific ratio of an engine rpm. and a cooling compressor's revolution number may not be maintained for a certain period. CONSTITUTION:By turning a switch 6 on, a decision circuit 3 is maintained at L level for a certain period during which a delay circuit 3B outputs H level. A relay circuit 4 electrifies a solenoid clutch 5 for driving a compressor. The compressor is quickly raised while the decision circuit 3 initiates the decision of speed ratio based on both an engine rpm. detection signal 1A and a compressor speed detection signal 1B. If the ratio is 0.8 or more, the decision circuit maintains the original L level, allowing a compressor to continue its drive. If the speed ratio drops below 0.8 and the duration thereof exceeds the time set by the delay circuit 3B, the relay circuit 4 is activated to disengage the solenoid clutch 5 so as to stop the compressor. A malfunction attributed to ignition noise or fluctuation of voltage and a secondary failure as well may be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an air-cooling part of an apparatus for air-conditioning a passenger compartment of an automobile, that is, a cooling apparatus.

In general, air conditioners dedicated to cooling or equipped with a reheating section for cooling air (1) operate a refrigerant compressor that receives rotational driving force from an automobile engine, and uses the refrigerant that is circulated thereby. The cooling heat exchanger is configured to absorb heat.

However, if the effect of the lubricating oil mixed with the refrigerant gas is weakened due to a lack of refrigerant gas in the compressor, or if the compressor locks up and stops due to damage to parts, the automobile engine or electromagnetic clutch A large load is applied to the connected parts such as, and there is a risk of secondary failure.

The purpose of the present invention is to prevent the above-mentioned secondary failures and also to prevent erroneous judgments due to vehicle ignition system noise, power supply voltage fluctuations, etc., by setting a delay effect in the judgment and using a delayed output to control the electromagnetic clutch. The compressor is configured to shut off and stop the compressor, thereby preventing erroneous operation due to external disturbances.

To explain the illustrated embodiment of the present invention, (2) In FIG. 1, LA is a first timing sensor that generates a pulse signal in synchronization with the rotation of the output shaft of an automobile engine; This is a second timing sensor that emits a pulse signal in synchronization with the rotation of the central shaft of the compressor, which transmits the rotational torque generated on the shaft through a pulley (not shown) and a heald (not shown), as well as the electromagnetic clutch 5. The frequency of the pulse signals generated by each of these sensors is proportional to the shaft rotational speed of the engine and compressor, respectively.

1 and 2 are F-V conversion circuits that convert pulse signals from the first and second timing sensors into frequency and voltage;
The value of the DC voltage present at the output of each conversion circuit corresponds to the frequency of the input cabling signal and thus to the engine speed or compressor speed.

3 is an abnormality determination circuit, and the above two F-V conversion circuits J, 2
It consists of a voltage comparison circuit that compares the output voltages of the two. While the compressor rotation speed/engine rotation speed ratio is normally about 1, it drops significantly when the compressor is locked. For this reason (3), this comparator circuit is set to generate the I-Level signal when the speed ratio is, for example, 0.8 or less. For example, the output voltage of the engine-side conversion circuit 1 may be divided into 415 voltages to be used as one input of the comparison circuit, and the output voltage of the compressor-side conversion circuit 2 may be used as the other input of the comparison circuit. The determination circuit 3 determines that the speed ratio is 0.81;
) above, and when the 17 level falls below 0.8, an output signal of II level is generated U7.

3A is a delay circuit that sets the output of the determination circuit 3 to level 17 for a certain period of time when power supply is started.

3B is a delay circuit which signals a 17 level output when the 1 level output of the determination circuit continues for a predetermined period of time.

Reference numeral 4 designates a relay circuit that responds to the output signal from the delay circuit 3B, and is constructed using a contact relay, the contact of which is connected to the ground side energizing path of the electromagnetic clutch 5.

6 is a main switch installed on the power supply path from the vehicle battery, and is called an air conditioner switch. Note that power supply lines to each circuit are not shown (4).

In the configuration described in 2, when the switch 6 is turned on, the output of the determination circuit 3 is at the level ■ for a certain period of time, so the delay circuit produces an 11 level output during that time, and the relay circuit 4 outputs the level 11 of the electromagnetic clutch 5. With one end grounded, the electromagnetic clutch 5 is energized and biased to drive the compressor. The rotation speed of the compressor quickly rises, and the judgment circuit 3
It becomes possible to determine the speed ratio.

The determination circuit 3 generates an L level output when the speed ratio is 0.8 or more to maintain the compressor driving state, but when the speed ratio is 0.8 or more, the determination circuit 3 generates an L level output to maintain the compressor driving state.
8 or less and when the condition exceeds the time limit set in the delay circuit 313, the relay contact of the relay circuit 4 opens to cut off the energization of the electromagnetic clutch 5. Since the rotational speed of the compressor becomes zero, the determination circuit 3 continues to produce an H level output, and the compressor remains stopped.

Here, the delay circuit 3B functions so that the electromagnetic clutch 5 does not become energized (5) even if the output of the determination circuit 3 momentarily goes to the H level without making a proper determination.

A detailed example of the delay circuit 3B is shown in FIG. 7 is a comparator, and the connection point B between the resistor 8 and the capacitor 9 is determined depending on whether the output of the judgment circuit 3 is at I, level or I] level with respect to the reference potential at point A divided by resistors 7A and 7B. The device is configured to compare whether the potential is high or not and output a drive signal for the electromagnetic clutch. 11 is an output end of a constant voltage power supply (not shown).

To explain the operation of this circuit, if the speed ratio is currently in the normal range and the judgment circuit 3 is outputting a level, the potential at point B will be approximately equal to the divided potential of resistor 8.10, and this Since the value is set to be lower than point A, the output of comparator 7 is I-level.

Next, when the speed ratio is within the above range, the determination circuit 3 produces an output of 1 lb. In this case, capacitor 9 is resistor 8 and resistor 10.
The potential at point B rises with a time constant determined by the parallel resistance and capacitance. Eventually, the potential at point B becomes A
When the point potential is exceeded, the output of the comparator 7 becomes the I5 level.

(6) However, when the speed ratio is within the normal range, even if the determination circuit 3 outputs 1 Hz for a very short time due to a sudden change in the power supply voltage, for example, the output of the delay circuit 3B will not reach the L level. , since it takes a set amount of time, the compressor will not stop accidentally.

Note that the combination -0 of the delay circuit 3B and the determination circuit 3 is not limited to the above-mentioned embodiment, and can be modified, for example, a digital processing circuit may be required.

Since the present invention has a delay function for determination as described in ``2'' below,
This has the excellent effect of being able to reliably stop the cooling device in the event of an abnormality without causing malfunctions due to disturbances or the like.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing one embodiment of the present invention, and FIG. 2 is an electrical wiring diagram showing details of the delay circuit 3B in FIG. IA...first timing sensor (first detection means)
, 2A... Second timing sensor (second detection means), 1.2... Frequency voltage conversion circuit, 3... Size (7
) constant circuit, 3B...delay circuit (conversion circuit 1.2 and determination circuit 3 form calculation means), 4...relay circuit,
5...Electromagnetic clutch, 6...Main switch. Representative patent attorney Oka i1+ Takashi (8)

Claims (1)

[Claims] a first detection means responsive to the rotational speed of an automobile engine; a second detection means responsive to the rotational speed of a cooling compressor driven by the engine via an electromagnetic clutch; and the first and second detection means. A calculation that determines whether the speed ratio of (compressor rotational speed/engine rotational speed) is in a predetermined ratio relationship based on a detection signal from the means, and generates an output signal when a state in which the predetermined ratio relationship is not present exceeds a predetermined time. and relay means for disconnecting the electromagnetic clutch based on the output signal of the calculation means.