JPH022662Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) This invention relates to a protection device for an automobile air conditioner, and is particularly provided with a slippage determination function.

(Prior art) Conventionally, as this type of device, for example, JP-A-58-
As shown in Japanese Patent No. 71213, there is a known system that compares the rotational speed of a driving engine and the rotational speed of a compressor to determine whether or not the compressor is slipping.

In this device, an electromagnetic clutch for switching on and off the compressor is turned on and off in accordance with the result of slippage determination, and a lamp is displayed to indicate the presence or absence of slippage.

(Problems to be Solved by the Invention) However, in the above conventional example, separate control means are required to control the operation of the electromagnetic clutch and the lamp according to the judgment result of the slip judgment means. Therefore, there was a problem that the circuit became complicated.

Therefore, this invention solves the above-mentioned problems of the conventional method and provides a protection device for an automobile air conditioner that can both control an electromagnetic clutch based on slippage judgment and display a warning for the presence or absence of slippage with a simple configuration. The challenge is to do so.

(Means for Solving the Problems) However, the gist of this invention is to provide a first rotation detection means for detecting the rotation speed of a driving engine, and an electromagnetic device for intermittent transmission of the driving force of the engine. a second rotation detection means for detecting the rotation speed of the compressor having a clutch, and comparing the output of the first rotation detection means and the output of the second rotation detection means to determine whether or not the compressor is slipping. In a protection device for an air conditioner for an automobile, comprising a slip determination means for determining, and a display means for displaying that slip has occurred in the compressor, the electromagnetic clutch is turned on and off according to the determination result of the slip determination means. A switching relay is provided for switching between energization of the display means and the display means.

(Function) Therefore, the above-mentioned problem can be achieved because the energization of the electromagnetic clutch and the energization of the display means are switched via a switching relay that is turned on and off depending on the result of the slippage determination means.

(Example) Hereinafter, an example of this invention will be described 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 intermittently by a control circuit 11, which will be described later.

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

Reference numeral 9 denotes a second rotation detector for detecting the rotation speed of the compressor 2, and for example, the electromagnetic pickup or the like is used.

10 is a temperature sensor that detects the temperature of the evaporator 4.

The control circuit 11 includes the first rotation detector 8, the second
Signals are input from the rotation detector 9 and temperature sensor 10 of the electromagnetic actuator 6, the abnormality indicator lamp 60 and the blower 5 based on these input signals.
It controls the operation of the following.

1 and 2 show a concrete circuit example of the control circuit 11, and 12 is an air conditioning switch,
When the air conditioning switch 12 is turned on, voltage is applied to the automobile air conditioner and this protection device.

Reference numeral 13 denotes a control unit for determining slippage, and the common contact 14a of the switching relay 14 is connected to the other end of the air conditioning switch 12, and the normally open contact 14b is connected to one end of the excitation coil 15a of the air conditioning relay 15. The other end of the coil 15a is connected to the output of the thermoswitch 16.

Further, one end of the abnormality indicator lamp 60 is connected to the normally closed contact 14c of the switching relay 14, and the other end of the abnormality indicator lamp 60 is grounded.

The thermoswitch 16 operates so that the air conditioning relay 15 is de-energized when the temperature detected by the temperature sensor 10 falls 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 switching relay 14 is de-energized, the normally open contact 14b is opened, and the normally closed contact 14c is closed. As a result, the abnormality indicator lamp 60 lights up, the electromagnetic clutch 6 is turned off simultaneously with the de-energization of the air conditioning relay 15, and the compressor 2 stops operating.

Furthermore, 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 15 is turned off by the operation of the thermoswitch 16. Compressor 2 stops operating.

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

Further, an exciting coil 18 of an FICD device (not shown) is connected in parallel with the exciting coil 6a of the electromagnetic clutch 6.
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. A rotation detection signal of the driving engine 1 detected by the first rotation detector 8 is input to the first rotation signal conversion circuit 102 . Transistors 20, 21
constitutes 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. This operational amplifier 22 constitutes a monostable multivibrator circuit,
When a signal is input to the inverting input terminal, the resistor 2
A square wave signal having a time constant determined by 3, 24 and a capacitor 25 is output to the output terminal of the operational amplifier 22. The output signal of the first rotation signal conversion circuit 102 is transmitted to the resistor 26
The signal is input to the slip determination circuit 105 via a slip detection delay circuit 110 composed of a capacitor 27 and a capacitor 27.

103 is a second rotation signal conversion circuit;
A frequency-voltage conversion circuit substantially similar to the rotation signal conversion circuit 102 is configured.

The second rotation signal conversion circuit 103 includes the second rotation signal conversion circuit 103.
The rotation detection signal of the compressor 2 detected by the rotation detector 9 is input, and the transistors 29 and 30
The signal is shaped into a square wave signal by a waveform shaping circuit consisting of the following components, and is applied to the non-inverting input terminal of the operational amplifier 31.

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 transmitted to the operational amplifier 3.
Output to output terminal 1. This operational amplifier 31
The output voltage is taken out as an integrated voltage by a capacitor 52, and is inputted to a slippage determination circuit 105, which will be described later, via a resistor 34. Furthermore, in the second rotational signal conversion circuit 103, even if there is no input signal, a predetermined time is required until the output voltage becomes zero due to the discharging action of the resistors 50, 51 and the capacitor 52. Therefore, if an input signal is input again during this period, the output voltage will return to the original potential without becoming zero, so that the slip determination circuit 105, which will be described later, is prevented from determining that there is a slip. It's summery.

104 is an operation detection circuit, and the excitation coil 6a of the electromagnetic clutch 6 is connected to the anode 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 diode 35 is turned on, so that the transistor 2
0 remains off until the electromagnetic clutch 6 is energized. The output voltage of the slip 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 in order 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, which determines and outputs the presence or absence of slippage 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 is connected to the first and second rotational signal conversion circuits 102 and 10.
Both of the output voltages of 3 are input to the inverting input terminal of the operational amplifier 36. Therefore, when the driving 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 reference voltage determined by resistors 37 and 38 and a variable resistor 39 is applied to the non-inverting input terminal of the operational amplifier 36, and when the voltage at the inverting input terminal becomes equal to or lower than this reference voltage, When the rotational speed becomes less than a predetermined value with respect to the rotational speed of the driving engine 1, the operational amplifier 36 outputs an "H" signal. Note that the predetermined value can be varied by the variable resistor 39.

Further, an electrolytic capacitor 40 is connected in parallel to the resistors 38 and 39, 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 the device, so that the output signal does not change during this period. It becomes “L”. That is, this is equivalent to not performing the slippage determination, and the switching relay 14 is forcibly turned on as described later. After the predetermined time has elapsed, the operational amplifier 36 normally performs the slip determination.

106 is a drive circuit, which is connected to the slip determination circuit 10;
The switching relay 14 is driven in accordance with the output signal of 5.

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

Note that a resistor 42 and a diode 4 are connected to the emitter of the transistor 41 that drives the switching relay 14.
3 to the inverting input terminal of the operational amplifier 36.

Therefore, when it is determined that there is a slip in the slip judgment and the switching relay 14 is turned off, 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 " H” and at the same time the switching relay 1
4 will be maintained in the off state. The switching relay is released from the off state by turning the power on and off.

Next, the operation of the protection device having the above structure will be explained with reference to the flowchart of FIG. 4.

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 the slippage determination circuit 105
In this case, it takes a predetermined time for the reference voltage of the operational amplifier 36 to rise.
outputs an output signal "H" regardless of the presence or absence of slippage, and the switching relay 14 is turned off during that time and the compressor 2
is also turned off. In FIG. 4, step 20
1 corresponds to this state.

In this case, the abnormality lamp 60 is turned on by closing the normally closed contact 14c of the switching relay 14, but the abnormality indicator lamp 60 is not turned on for a predetermined period of time until the switching relay 14 is energized. Since it is recognized visually and takes only a short time, it does not actually cause an abnormal display and does not pose a problem.

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 an "L" signal, the switching 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 unless the thermoswitch 16 is operated.

When the evaporator (not shown) cools down to a predetermined temperature or lower, the thermoswitch 16 operates to de-energize the air conditioning relay 15, and the diode 35 of the operation detection circuit 104 is biased in the forward direction. . Therefore, the first rotation signal conversion circuit 102
Since the predetermined bias voltage is no longer applied to the base of the transistor 20, the output voltage of the slip detection delay circuit 110 is fixed at approximately _V1 , and the switching relay 14 is fixed regardless of whether or not the compressor 2 is slipping.
will be maintained in the on state (corresponding to step 203 in FIG. 4).

Next, as the temperature of the evaporator rises, the thermoswitch 16 is activated to excite the excitation coil 6a, and the compressor 2 is turned on from the off 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 determination circuit 105,
Even if a slip occurs during this period, the slip determination circuit 10
5, it is not determined that there is slippage. After a predetermined period of time has elapsed, the slippage determination circuit 105 continues to output an "L" signal if the output voltages of the first and second rotation signal conversion circuits 102 and 103 are normal;
Turn on the switching relay 14 (Step 2 in Fig. 4)
04-209).

Finally, in the case of slippage, the second
Due to the action of the resistors 50, 51 and the capacitor 52 of the rotation detection circuit 103, in the case of a short slip less than the time constant of the resistors 50, 51 and the capacitor 52, the inverting input terminal of the operational amplifier 36 is detected in the slip judgment circuit 105. Since the voltage at the non-inverting input terminal does not become lower than the reference voltage of 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 an "H" signal and switches the switching relay 14 on. Turn off. 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 switching relay 14 is kept in the OFF state (steps 208 and 209 in FIG. 4). ). Therefore, the compressor 2 is kept in a stopped state.

At the same time, the abnormality lamp 60 is kept lit by closing the normally closed contact 14c.

Note that this off state is canceled by opening the air conditioning switch 12 and then turning it on again.

In this embodiment, an electromagnetic clutch 6 is connected to a normally open contact 14b of a switching relay 14 via an air conditioning relay 15.
Although it was designed to be connected, it may also be possible to use it in reverse. Furthermore, although the abnormality indicator lamp 60 is connected to the normally closed contact 14c, an alarm buzzer may also be used.

(Effects of the Invention) As described above, according to this invention, the electromagnetic clutch that turns on and off the compressor and the display means that displays the slippage can be controlled by one control means, so it is easy to use. It is possible to provide a protection device for an automobile air conditioner that can perform on/off control of a compressor according to the result of slippage determination using a circuit and display when slippage has occurred.

Furthermore, the reliability of the device is improved by simplifying the circuit.

[Brief explanation of drawings]

Fig. 1 is a schematic circuit diagram showing an embodiment of the protection device according to the invention, Fig. 2 is a specific circuit diagram of the same protection device, Fig. 3 is a schematic configuration diagram of the same protection device, and Fig. 4 is the same as the above. 2 is a flowchart showing the operation of the protective device. 6...Electromagnetic clutch, 14...Switching relay, 6
0...Error indicator lamp.

Claims (1)

[Scope of utility model registration request] a first rotation detection means for detecting the rotation speed of a driving engine; a second rotation detection means for detecting the rotation speed of a compressor having an electromagnetic clutch for intermittent transmission of the driving force of the engine; a slip determining means for comparing the output of the rotation detecting means with the output of the second rotation detecting means to determine the presence or absence of slip in the compressor; and a display means for displaying that slip has occurred in the compressor. A protection device for an automotive air conditioner comprising: a switching relay that is turned on and off according to the judgment result of the slip judgment means to switch between energization of the electromagnetic clutch and energization of the display means. Protection device for automotive air conditioners.