JPS62279115A - Protector for car air conditioner - Google Patents

Abstract

PURPOSE:To prevent the wrong detection of slip judgment from occurring, by installing a device which compares signals conformed to each rotational frequency of an engine and a compressor and performs the slip judgment, and delaying operation of a slip judging device as long as the specified time when the compressor comes into a state of being operated. CONSTITUTION:Each speed detecting signal of a running engine and a compressor is inputted into both speed signal conversion circuits 102 and 103. Signals out of both these speed signal conversion circuits 102 and 103 are compared at a judging circuit 105 and whether there is a slip or not is judged. In this case, when the compressor comes into a state of being turned ON from OFF, the signal out of the speed signal detecting circuit 102 is delayed as long as the specified time by a slip detection delaying circuit 110 and impressed on the slip judging circuit 105 so that during this while, if the slip is produced there, this slip generation is not judged at all. With this constitution, any wrong detection for the slip detection immediately after being turned on or off in the compressor is avoidable.

Description

[Detailed Description of the Invention] 3. Detailed Description of the Invention (Field of Industrial Application) This invention relates to a protection device for an automobile air conditioner, and in particular, a protection device for an automobile air conditioner by detecting compressor rotational slip. It is something.

(Prior art) Conventionally, as this type of device, for example, Japanese Patent Application Laid-Open No. 58-335
As shown in Publication No. 17, it is determined whether or not there is slippage in the rotation of the compressor by comparing the rotational speed of the running engine and the rotational speed of the compressor in the cooling cycle. There is a known method for protecting an automobile air conditioner by cutting off the compressor.

(Means for solving the problem) However, in the above-mentioned device, when a so-called thermoswitch circuit is used, for example, which detects the temperature of the evaporator and turns off the compressor when the temperature is below a predetermined temperature, the thermoswitch circuit There is also a problem in that the above-mentioned slip judgment is performed even when the compressor rotation occurs when the compressor changes from an off state to an on state due to the operation of the compressor, and the compressor is cut off again.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a protection device for an automobile air conditioner that does not cause false detection.

(Means for Solving the Problems) Therefore, the gist of the present invention is to receive a rotation detection signal with a period corresponding to the rotation speed of a traveling engine, and to output an output signal corresponding to the frequency of the rotation detection signal. The first to generate
a second rotation signal conversion means that receives a rotation detection signal with a period corresponding to the rotation speed of the compressor and generates an output signal according to the frequency of the rotation detection signal;
slippage determination means for detecting occurrence of slippage by comparing the output signal of the rotation signal conversion means with the output signal of the second rotation signal conversion means; and operation detection means for detecting whether the compressor is activated or not. and a delay means for delaying the operation of the fullness determining means for a predetermined period of time when the operation detecting means detects that the compressor changes from an inoperative state to an operating state. protection device.

(Operation) Therefore, immediately after the compressor changes from the off state to the on state, the fullness determination is not performed for a predetermined period of time.

After that, the normal slippage judgment is performed, so for this reason,
The above-mentioned problems can be achieved.

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

In FIG. 3, 1 is a driving engine, 2 is a compressor, and an evaporator 4 disposed in an air conditioning duct 3 and other condensers (not shown) constitute a cooling cycle.

A blower 5 for blowing air to the evaporator 4 is provided upstream of the air conditioning duct 3.

The compressor 2 is driven by the traveling engine 1 via an electromagnetic clutch 6 and a belt transmission mechanism 7.

The operation of the electromagnetic clutch 6 is controlled on and off by a control circuit 11, which will be described later.

Reference numeral 8 denotes a first rotation detector for detecting the rotation speed of the driving engine, and is used, for example, by attaching an ignition coil in a gasoline vehicle or by attaching an electromagnetic pickup to a fuel injection pump in a diesel vehicle.

A second rotation detector 9 detects the rotation speed of the compressor 2, and the electromagnetic pickup or the like is used, for example.

1o is a temperature sensor that detects the temperature of the evaporator 4.

The control circuit 11 includes the first rotation detector 8. Signals are input from the second rotation detector 9 and temperature sensor 10, and the operations of the electromagnetic actuator 6, blower 5, etc. are controlled based on these input signals.

1 and 2 show a specific circuit example of the control circuit 11, 12 is an air conditioning switch, and when the air conditioning switch 12 is turned on, voltage is applied to the automobile air conditioner and the protection device. 6 13 Built-in relay 1 in the control unit that performs the fullness judgment
4 common contact 14a is connected to the other end of the air conditioning switch 12, the normally open contact 14b is connected to one end of the excitation coil 15a of the air conditioning relay 15, and the other end of the excitation coil 15a is connected to the output of the thermoswitch 16. It is connected to the.

The thermoswitch 16 operates so that the air conditioning relay 15 is de-energized when the temperature detected by the temperature sensor 1o is below a predetermined temperature, and its configuration is well known and will not be described in detail.

Further, the normally open contact 15a of the air conditioning relay 15 is connected in series with the excitation coil 6a of the electromagnetic clutch 6 and connected to a power source.

When the control unit 13 determines that there is slippage, the built-in relay 14 is de-energized and the normally open contact 14b is closed, so the air conditioning relay 15 is also de-energized, and as a result, the electromagnetic clutch 6 is turned off and compression is not performed. Machine 2 stops operating.

Further, even if it is determined that there is no slippage, if the temperature of the compressor 2 falls below the predetermined temperature set by the thermoswitch 16, the air conditioning relay IS is turned off by the operation of the thermoswitch 16, and the compressor 2 stops operation.

Note that 17 is a blower switch for turning the blower 17 on and off.

Further, F is connected in parallel with the excitation coil 6a of the electromagnetic clutch 6.
An excitation coil 18 of an ICD device (not shown) is connected.

FIG. 2 shows a specific circuit example of the control unit 13.

A power supply circuit 101 supplies a predetermined stabilized voltage to each circuit constituting the control unit 13, and the output voltage is determined by a Zener diode 19.

Reference numeral 102 denotes a first rotational signal conversion circuit, which constitutes a so-called frequency-voltage conversion circuit that outputs a voltage according to the frequency of an input signal. The first rotation signal conversion circuit 10
A rotation detection signal of the driving engine 1 detected by the first rotation detector 8 is inputted to the engine 2. The transistors 20 and 21 constitute a waveform shaping circuit, and the rotation detection signal is shaped into a square wave signal and applied to the inverting input terminal of the operational amplifier 22. The operational amplifier 22 constitutes a monostable multivibrator circuit, and when a signal is input to the inverting input terminal, a square wave signal having a time constant determined by the resistors 23 and 24 and the capacitor 25 is transmitted to the operational amplifier 22. It is configured to be output to the output terminal.

The output signal of the first rotation signal conversion circuit 102 is
The signal is input to the slippage determination circuit 105 via a slippage detection delay circuit 110 composed of a resistor 26 and a capacitor 27.

Reference numeral 103 denotes a second rotational signal conversion circuit, which is configured as a frequency-voltage conversion circuit substantially similar to the first rotational signal conversion circuit 102.

The rotation detection signal of the compressor 2 detected by the second rotation detector 9 is inputted to the second rotation signal conversion circuit 103, and a square wave signal is converted into a waveform shaping circuit composed of transistors 29, 30, etc. Operational amplifier 3
1 non-inverting input terminal.

The operational amplifier 31 forms a monostable multivibrator circuit, and when a signal is applied to the non-inverting input terminal, a square wave signal having a time constant determined by the resistor 32 and the capacitor 33 is applied to the output terminal of the operational amplifier 31. Output.

The output voltage of the operational amplifier 31 is taken out as an integrated voltage by a capacitor 52, and is inputted via a resistor 34 to a slip determination circuit 105, which will be described later. Further, in the second rotational signal conversion circuit 103, even if the input signal disappears, a predetermined time is required until the output voltage becomes zero due to the discharging action of the resistor 50, 51 and the capacitor 52. Therefore, if the input signal is input again during this period, the output voltage will not become zero but will return to the original potential, which will prevent the slip determination circuit 105 (to be described later) from determining that there is a slip. There is.

Reference numeral 104 denotes an operation detection circuit, and the excitation coil 6a of the electromagnetic clutch 6 is connected to seven nodes of the diode 35 constituting the circuit 104.

Therefore, when the electromagnetic clutch 6 is turned off, a forward bias current flows through the diode 35 and the transistor 20 is turned on, so that the transistor 20 remains off until the electromagnetic clutch 6 is energized. Then, the output voltage of the overflow detection delay circuit 110 is maintained at approximately voltage v1.

On the other hand, when the electromagnetic clutch 6 is turned on from the off state, the first rotation signal conversion circuit 102 outputs a square wave signal again, but for the output voltage of the slip detection delay circuit 110 to reach a predetermined voltage, A predetermined period of time is required due to the charging action of the capacitor 27.

Reference numeral 105 denotes a slippage determination circuit that determines and outputs the presence or absence of burr based on the output voltages of the first and second rotational signal conversion circuits 102 and 103.

The operational amplifier 36 constitutes a comparison circuit, and the output voltages of the first and second rotational signal conversion circuits 102 and 103 are both input to the inverting input terminal of the operational amplifier 36.

Therefore, when the running engine 1 and the compressor 2 rotate normally, a constant voltage is applied to the inverting input terminal of the operational amplifier 36.

On the other hand, a resistor 3 is connected to the non-inverting input terminal of the operational amplifier 36.
7.38 and the variable resistor 39 is applied, and when the voltage at the inverting input terminal becomes less than this reference voltage, that is, the rotation speed of the compressor 2 is at a predetermined level with respect to the rotation speed of the driving engine 1. If the value is below the value, the operational amplifier 3
6 is configured to output a signal multiplied by HIt. The predetermined value can be varied by the variable resistor 39.

Further, an electrolytic capacitor 4 is connected in parallel to the resistor 38, 39.
0 is connected, and forms a time constant circuit together with the resistor 37. Due to the action of this time constant circuit, the reference voltage of the operational amplifier 36 is lower than the input voltage of the inverting input terminal for a predetermined period of time immediately after the power is turned on to this device, so the output signal during this period is lower than II L. ”. That is,
This is equivalent to not performing a slippage determination, and the built-in relay 14 is forcibly turned on as described later. and,
After the predetermined time has elapsed, the operational amplifier @36 normally performs the slip determination.

Reference numeral 106 denotes a drive circuit that drives the built-in relay 14 in accordance with the output signal of the slip determination circuit 105.

The normally open contact 14b of the built-in relay 14 is connected to the air conditioning relay 15.
The excitation coil 15a is connected in series with the excitation coil 15a. Therefore, the electromagnetic clutch 6 is turned on and off via the built-in relay 14 and the air conditioning relay 15 depending on the presence or absence of slippage.

The emitter of the transistor 41 that drives the built-in relay 14 is connected to the inverting input terminal of the operational amplifier 36 via a resistor 42 and a diode 43.

Therefore, when the built-in relay 14 is turned off because it is determined that there is a slip, the inverting input terminal of the operational amplifier 36 is forcibly pulled down to approximately zero potential, so the operational amplifier 36 outputs the output signal "' At the same time, the built-in relay 14 is kept in the OFF state. The built-in relay is released from the off state by turning the power on and off.

Next, the operation of the protection device having the above configuration will be explained with reference to the fourth J flowchart.

First, when the air conditioning switch 12 and the blower switch 17 are turned on, power is applied through the air conditioning switch 12, so it takes a predetermined time for the reference voltage of the operational amplifier 36 to rise in the slip determination circuit 105, so that the The operational amplifier 36 outputs an output signal ``H'' regardless of the presence or absence of slip, and the built-in relay 14 is turned off during this time, and the compressor 2 is also turned off. In FIG. 4, step 201 corresponds to this state.

Next, if the rotation of both the driving engine 1 and the compressor 2 is normal after the predetermined time has elapsed.

The operational amplifier 36 outputs a signal multiplied by rt L pp, the built-in relay 14 is turned on, and the normally open contact 14a is closed (corresponding to step 202 in FIG. 4). therefore.

The operating state of the compressor 2 is maintained as long as the thermoswitch 16 is not operated.

When the evaporator (not shown) cools down to a predetermined temperature or lower, the excitation of the air conditioning relay 15 is cut off by the operation of the thermoswitch 16, and the diode 35 of the 1-operation detection circuit 104 is biased in the forward direction. Therefore, the predetermined bias voltage is no longer applied to the base of the transistor 20 of the first rotational signal conversion circuit 102, so the output voltage of the slip detection delay circuit 110 is fixed at approximately vi, and whether or not there is slip in the compressor 2 is determined. Regardless of the situation, the built-in relay 14 will be maintained in the on state (corresponding to step 203 in FIG. 4).

Next, if the thermoswitch 16 operates to excite the excitation coil 6a due to the temperature rise of the evaporator, the compressor 2
changes from off state to on state.

At the same time, the diode 35 of the operation detection circuit 104 becomes reverse biased, so the first circuit signal detection circuit 102 shifts to normal operation.

However, since the output voltage of the first circuit signal detection circuit 102 is delayed by the slip detection delay circuit 110 and applied to the slip judgment circuit 105, even if a slip occurs during this period, the slip judgment circuit 105 will not detect a slip. It is not determined that Then, after a predetermined period of time has elapsed, the completeness determination circuit 10
If the output voltages of the first and second rotational signal conversion circuits 102 and 103 are normal, 5 continues to output the "LH" signal and turns on the built-in relay 14 (corresponding to the 4th rJ!I steps 204 to 209). do).

Finally, in the case where a slip occurs, the action of the resistors 50, 51 and capacitor 52 of the second rotation detection circuit 103 prevents a short slip that is less than the time constant of the resistor 50, 51 and capacitor 52. The slip determination circuit 1
At step 05, since the voltage at the inverting input terminal of the operational amplifier 36 does not become lower than the reference voltage at the non-inverting input terminal, it is not determined that there is a slip (corresponding to steps 208 and 210). However, when a slip exceeding the time constant occurs, the input voltage at the inverting terminal of the operational amplifier 36 of the slip determination circuit 105 becomes lower than the reference voltage, so the operational amplifier 36 outputs a "Hjj times signal and turns off the built-in relay 14. At this time, the voltage at the non-inverting input terminal of the operational amplifier 36 is forcibly lowered through the resistor 42 and diode 43, so that the built-in relay 14 is kept in the OFF state (step 4 in FIG. 4). 208 and 209), this off state is canceled by opening the air conditioning switch 12 and then turning it on again.

In this embodiment, the built-in relay 14 is used in the excitation circuit of the excitation coil 6a of the electromagnetic clutch 6, but it may also be used to turn on and off an alarm, etc. that indicates the presence or absence of slippage.

(Effects of the Invention) As described above, according to the present invention, an air conditioner for an automobile that performs slippage determination by comparing a signal corresponding to the rotation speed of the driving engine and a signal corresponding to the rotation speed of the compressor. In the protection device, when the compressor changes from an OFF state to an ON state, the slippage determination is delayed for a predetermined period of time, so slippage that occurs immediately after startup is detected when the compressor is turned on and off using a thermoswitch, etc. To perform a reliable slippage judgment without false detection, and to set the slippage judgment conditions without considering the conditions to avoid the above-mentioned erroneous judgment immediately after the compressor is turned on and off. This has the effect of making accurate veri determination.

[Brief explanation of the drawing]

Fig. 1 is a schematic circuit diagram showing an embodiment of the protection device according to the present invention, Fig. 2 is a specific circuit diagram of the same protection device, and Fig. 31!
I is a schematic configuration diagram of the above protection device, and FIG. 4 is a flowchart showing the operation of the same protection device. 102... First rotation signal conversion circuit, 103... Second rotation signal conversion circuit, 104... Operation detection circuit, 1
05... Slip determination circuit, 110... Slip detection delay circuit.

Claims (1)

[Claims] a first rotation signal conversion means that receives a rotation detection signal with a period corresponding to the rotation speed of the driving engine and generates an output signal according to the frequency of the rotation detection signal; a second rotation signal converting means that receives a rotation detection signal and generates an output signal according to the frequency of the rotation detection signal; and an output signal of the first rotation signal conversion means and the second rotation signal conversion means. a slip determination means for detecting the occurrence of slip by comparing the output signal with the output signal; and operation of the compressor;
an operation detection means for detecting non-operation; and a delay means for delaying the operation of the slippage determination means for a predetermined period of time when the operation detection means detects that the compressor has changed from an inoperation state to an operation state. A protection device for an automotive air conditioner, characterized by comprising: