JPH0234424A - Car airconditioning control device with variable capacity compressor - Google Patents

Abstract

PURPOSE:To prevent a magnet clutch from seizing by carrying out normal variable capacity control during inner air circulation and minor quantity control during outer air introduction, and by eliminating abnormal rise of the discharge pressure of compressor. CONSTITUTION:The body of a control device includes a refrigerator circuit, in which a variable capacity compressor 1, condenser 2, receiver dryer 3, automatic expansion valve 4 and evaporation 5 are connected with one another. These components 4-6 are arranged in a duct 7 to constitute a unit 8. The changeover position of an intake door 9 installed rotatably at the inlet to the duct 7 is sensed by a limit switch 12. On the basis of this sensed changeover position, an electromagnetic actuator 1a driving the compressor 1 is controlled by a control circuit 13. That is, normal variable capacity control is conducted during inner air circulation, while minor capacity control is carried out during outer air introduction.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a vehicle air conditioning control device using a variable capacity compressor that can variably control the discharge capacity based on a control signal input from the outside, particularly for a wagon vehicle. So-called cabovers such as
Relates to what is installed on a type of commercial vehicle.

(Prior Art) Conventionally, vehicle air conditioning control devices installed in such commercial vehicles are generally placed within the engine rule under the front seat of the vehicle, where the airflow introduced from the opening at the front of the vehicle is directed. The condenser is placed horizontally and is equipped with a fan to provide adequate coverage of the radiator.

(Problem to be Solved by the Invention) In such conventional vehicle air conditioning control devices, since the condenser is placed horizontally, sufficient heat dissipation capacity of the condenser cannot be ensured when outside air is introduced. When operating at high speed under high load with high temperature and high humidity, the amount of heat dissipated by the condenser is insufficient and the discharge pressure of the compressor tends to increase, and especially if the refrigerant is overfilled, the discharge pressure may become abnormal. This can cause damage to the compressor. In order to prevent this damage, a method is generally used in which when the discharge pressure rises above a limit value, a pressure protection switch is activated to turn off the compressor's magnetic clutch and stop the compressor.

However, with this method, if the discharge pressure falls below a limit value due to the compressor being stopped, the pressure protection switch is turned off and the compressor is restarted. Therefore, there is a problem in that when the pressure protection switch is operated more frequently, the magnetic clutch may burn out.

Note that during internal air circulation, the heat load is small, so even if the refrigerant is overfilled, the discharge pressure will hardly become abnormally high.

The present invention was made by focusing on these conventional problems, and allows the variable capacity compressor to perform normal variable capacity control when circulating indoor air, and also causes the compressor to perform small capacity control when outside air is introduced. By running and lowering the discharge pressure,
During high-speed operation under high load with high outside temperature and high humidity, this prevents the discharge pressure from becoming abnormally high even if the refrigerant is overfilled, prevents the magnetic clutch from seizing, and improves the compressor. The object of the present invention is to provide a vehicle air conditioning control device using a variable capacity compressor that can protect the air conditioner.

(Means for Solving the Problems) In order to achieve the above object, a vehicle air conditioning control device using a variable capacity compressor according to the present invention variably controls the discharge capacity using a control signal input from the outside. In a vehicle air conditioning control device using a variable displacement compressor, a position detection means detects a switching position of an intake door that switches between introducing inside and outside air, and a position detection means operates in response to an output signal from the position detection means, and detects the position. When the means detects the internal air circulation position of the intake door, it outputs a first control signal corresponding to the heat load to the variable displacement compressor to cause the compressor to perform normal variable displacement control, and also detects the position of the intake door. When the detection means detects the outside air circulation position of the intake door, outputs a second control signal to the variable capacity compressor mj to reduce the discharge capacity to a predetermined small capacity at which the discharge pressure is below the normal operating pressure. The compressor is equipped with a control circuit that causes the compressor to perform small capacity control.

(Function) In the vehicle air conditioning control device described above, during internal air circulation when the position detecting means detects the inside air ms position of the intake door, the control circuit normally controls the variable displacement compressor according to the output signal from the position detecting means. When outside air is introduced when the position detection means detects the outside air circulation position of the intake door, the control circuit causes the variable displacement compressor to perform small capacity control in accordance with the output signal from the position detection means. .

This small volume control reduces the discharge pressure.

(Example) Hereinafter, each embodiment of the present invention will be described based on the drawings.

FIG. 1 is a schematic configuration diagram showing a vehicle air conditioning control device according to a first embodiment of the present invention. This vehicle air conditioning control device is
It is installed in so-called cab-over type commercial vehicles such as wagons.

As shown in FIG. 1, the vehicle air conditioning control system includes a variable capacity compressor 1 placed in an engine room under a front seat of a vehicle (not shown), and a variable capacity compressor 1 placed horizontally in the engine room. , a refrigeration circuit in which a condenser 2 equipped with a fan, a receiver dryer 3, an automatic expansion valve 4, and an evaporator 5 are connected to each other by piping.

The automatic expansion valve 4, the evaporator 5, and the blower motor 6 are
It is arranged within the duct 7 and constitutes an evaporator unit 8. On the inlet side of the duct 7, there is an intake door 9 which is rotatable between an inside air circulation position shown in the figure and an outside air introduction position rotated clockwise around a fulcrum 9a from this position.
is located. The intake door 9 is connected via a link 11 to a mode switching lever 10 provided on an instrument panel of the vehicle. A limit switch 12 serves as a position detection means for detecting the switching position of the intake door 9 by the mode switching lever 10.
is provided. When the mode switching lever 1o is switched to the REC position (back air circulation position) shown in the figure, a portion 12a of the link 11 comes into contact with the limit switch 12, outputting an ON signal, and switching the mode switching lever 10 to the FRESH position.
When switched to the outside air introduction position, a portion 11a of the link 11 separates and outputs an off signal.

The variable displacement compressor 1 is a variable displacement swash plate compressor (hereinafter simply referred to as a compressor) whose discharge capacity is variably controlled by a control signal input from the outside (control circuit 13). The control signal is input from the control circuit 13 to the electromagnetic actuator la of the compressor l, and as the current value of the control signal increases, the discharge capacity decreases, and conversely, as the current value decreases, the discharge capacity increases. It is made up like this.

The input side of this control circuit 13 is connected to the output side of the limit switch 12 via a control line 14, and the output side thereof is connected to the electromagnetic actuator la via a control line 15, respectively.

This control circuit 13 operates according to the output signal of the limit switch 12, and when the limit switch 12 detects the inside air circulation position of the intake door 11 and outputs an on signal, the current value changes according to the heat load. The changing first control signal Sl (see FIG. 3) is outputted as the control signal to the electromagnetic actuator la to cause the compressor l to perform normal variable displacement control, and the limit switch 12 controls the intake door 11 from outside air. When the introduction position is detected and the off signal is output, the discharge volume and the discharge pressure are the normal pressure (approximately 14 to 1
A second control signal S2 (see FIG. 3) for reducing the capacity to a predetermined small capacity of 7 kg/cffl or less is output as the control signal to the electromagnetic actuator 1a to cause the compressor l to execute small capacity control. It consists of

The operation will be explained below based on the flowchart shown in FIG.

First, the limit switch 12 detects the switching position of the intake door 9 by the mode switching lever 10 (step 201), and the control circuit 13 determines whether the intake door 9 is in the outside air introduction position based on the output signal from the limit switch 12. (step 202). Step 202
When the answer is negative (No), that is, the mode switching lever 10
When the intake door 9 is switched to the inside air circulation position by switching to the REC position (inside air circulation position) shown in FIG. The first value changes
A control signal 81 is output to the electromagnetic actuator la to cause the compressor l to perform normal variable capacity control (step 2
04).

When the answer to step 202 is affirmative (Yes), that is, by switching the mode switching lever 10 to the FRESH position (outside air introduction position), the intake door 9 is switched from the position shown in FIG. 1 to the outside air introduction position rotated clockwise. When the off signal is output from the limit switch 12, the control circuit 13 adjusts the discharge capacity so that the discharge pressure is normal pressure (approximately 14 to 17k).
g/c+d) or less to a predetermined small capacity? output to the magnetic actuator la to cause the compressor l to perform small capacity control (step 203
).

As the compressor 1 executes the small capacity control in this way, the discharge pressure decreases below the normal pressure.

This prevents the discharge pressure from becoming abnormally high even if the refrigerant is overfilled during high-speed operation under high load with high outside temperature and high humidity. The clutch lb is prevented from burning out and the compressor 1 is protected.

In the above embodiment, the second control signal S2 is used as the control signal to reduce the discharge capacity of the compressor l to a predetermined small capacity at which the discharge pressure is below the normal pressure (approximately 14 to 17 kg/cnf). Although the control signal S2 is output to the actuator 1a, it is also possible to configure the control circuit 13 to output a control signal that sets the discharge capacity of the compressor 1 to the minimum capacity.

Next, a second embodiment of the present invention will be described based on FIG.

In this second embodiment, when the intake door 9 is switched to the outside air introduction position and the outside temperature is above a predetermined value (for example, 30° C.), the control circuit 13 sends the second control signal S2 to the electromagnetic actuator 1a. This output is used to cause the compressor l to perform small capacity control. That is, the control circuit 13
Step 403) determines whether the outside temperature detected by an outside temperature sensor (not shown) is above a predetermined value. If the answer is negative (No), that is, when the outside temperature is below the predetermined value, the control circuit 13 outputs the first control signal Sl to the electromagnetic actuator la to cause the compressor 1 to perform normal variable capacity control (step 405).

When the answer to step 403 is affirmative (Yes), that is, when the outside temperature is above a predetermined value, the control circuit 13 outputs the second control signal S2 to the electromagnetic actuator 1a to perform compression 1j.
11 to execute small capacity control (step 404).

(Effects of the Invention) As detailed above, according to the vehicle air conditioning control device using the variable capacity compressor according to the present invention, the position detecting means detects the switching position of the intake door that switches between introducing inside and outside air. , operated in response to an output signal from the position detection means;
When the position detecting means detects the internal air circulation position of the intake door, outputting a first control signal according to the heat load to the variable displacement compressor to cause the compressor to perform normal variable displacement control; , when the position detection means detects the outside air circulation position of the intake door, outputs a second control signal to the variable displacement compressor to reduce the discharge volume to a predetermined small volume at which the discharge pressure is below the normal pressure; and a control circuit that causes the compressor to perform small capacity control,
During internal air circulation when the position detecting means detects the internal air circulation position of the intake door, the control circuit causes the variable displacement compressor to perform normal variable displacement control according to the output signal from the position detecting means, and the position detecting means detects the intake door. When the outside air circulation position of the door is detected and outside air is introduced, the control circuit causes the variable displacement compressor to perform small capacity control in accordance with the output signal from the position detection means, and this small capacity control reduces the discharge pressure. When operating at high speed under high load with high outside temperature and high humidity, the discharge pressure is prevented from becoming abnormally high by 4° even if the refrigerant is overfilled, thereby protecting the compressor. can.

Further, according to the vehicle air conditioning control device using the variable capacity compressor according to the present invention, when outside air is introduced when the position detection means detects the outside air circulation position of the intake door, the control circuit receives the output signal from the position detection means. With a configuration that allows the variable capacity compressor to perform small capacity control according to the This makes it possible to reduce costs and make effective use of space.

[Brief explanation of the drawing]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a schematic configuration diagram showing a vehicle air conditioning control device, FIG. 2 is a flowchart showing the operation, and FIG. 3 is a control signal and discharge A graph showing the relationship with capacity, and FIG. 4 is a flowchart showing the operation of the vehicle air conditioning control device according to the second embodiment of the present invention. ■...Variable capacity swash plate compressor (variable capacity compressor)
, 9... Intake door, 12... Limit switch (position detection means), 13... Control circuit, Sl...
First control signal, S2... second control signal.

Claims (1)

[Claims] 1. In a vehicle air conditioning control device using a variable capacity compressor whose discharge capacity is variably controlled by a control signal input from the outside, a position detection means for detecting a switching position of an intake door that switches between introducing inside and outside air; When the position detecting means detects the internal air circulation position of the intake door, a first control signal corresponding to the heat load is output to the variable displacement compressor to compress the compressor. A second control that causes the machine to perform normal variable displacement control and, when the position detection means detects the outside air circulation position of the intake door, reduces the discharge volume to a predetermined small volume at which the discharge pressure is equal to or lower than the normal pressure. An air conditioning control device for a vehicle using a variable displacement compressor, comprising a control circuit that outputs a signal to the variable displacement compressor to cause the compressor to perform small capacity control.