JP3279001B2 - Automotive air conditioners - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioner for a motor vehicle, and more particularly to an air conditioner for a motor vehicle having a plurality of compressor stop command pressures.

[0002]

2. Description of the Related Art A conventional automotive air conditioner has a problem that when a refrigerant leaks from a refrigeration cycle or at a low outside air temperature, the return amount of compressor oil is reduced and the compressor is burned or damaged. The compressor is stopped and protected when the refrigerant drops below a certain amount or when a low outside air temperature is detected.

[0003] As a method, a pressure switch is provided in a pipe utilizing the correlation between the refrigerant pressure and the refrigerant amount and the correlation between the refrigerant pressure and the outside air temperature. Both the temperatures are determined, and the compressor is forcibly stopped usually at 0 ° C. or less.

[0004]

A conventional air conditioner for a vehicle employs a pressure switch which also serves as an outside air thermostat for detecting shortage of refrigerant and stopping the air conditioner based on the outside air temperature. Here, the characteristics of the pressure switch are shown in FIG. For example, Freon 134a (HFC-13
When 4a) is used, the set pressure of the pressure switch is P
The compressor is set to stop at a <0.196 MPa (around 0 ° C.) and to operate at Pb> 0.225 MPa (around 3 ° C.).

However, even when the outside air temperature is lower than a predetermined value (around 0 ° C.), there are cases where it is desired to operate the compressor to remove the fogging of the vehicle window glass. As a method,
As disclosed in Japanese Patent Publication No. 248, there is known a method of operating the compressor to a lower outside air temperature only when the inside / outside air switching door of the air conditioner is in the inside air mode even when the outside air temperature is equal to or lower than a predetermined value. However, this publication does not consider the shortage of the refrigerant.

Therefore, the outside air temperature is set to a predetermined value (around 0 ° C.).
Hereinafter, even if the compressor is to be operated in the inside air mode, the compressor is stopped by the refrigerant shortage determination by the pressure switch. Therefore, in order to operate the compressor until the outside air temperature reaches a predetermined value (around 0 ° C.), the set pressure of the pressure switch is set to a normal set value (0 ° C.).
(Around ℃). However, if the set pressure of the pressure switch is excessively lowered, the shortage of the refrigerant is delayed, and the compressor continues to operate even when the refrigerant is insufficient, which causes a problem that the compressor is destroyed. Further, there remains a problem that the fogging of the window glass cannot be removed unless the set pressure is reduced too much.

Accordingly, the present invention sets the set pressure for detecting the refrigerant shortage to a normal set value of 0.196 MPa (around 0 ° C.), accurately detects the refrigerant shortage, and operates the compressor even at a low outside air temperature. It is another object of the present invention to provide an air conditioner for a vehicle that can remove fogging of a vehicle window glass.

[0008]

In order to achieve the above object, the present invention provides, as shown in FIG. 4, a first temperature setting means for setting a first set temperature in an automobile air conditioner having a refrigeration cycle. An outside air temperature detecting means for detecting an outside air temperature; a first temperature judging means for outputting a judgment output when the temperature detected by the outside air temperature detecting means is equal to or lower than the first set temperature; Pressure detection means 35 for detecting the refrigerant pressure of the cycle, first pressure setting means 34 for setting a first set pressure, and judgment when the pressure detected by the pressure detection means 35 is equal to or lower than the first set pressure. A first pressure judging means 39 for outputting an output, and a compressor of the refrigeration cycle when a judgment output by the first temperature judging means 37 and a judgment output by the first pressure judging means 39 are output. A first control means 41 for stopping the,
A second temperature setting means for setting a second set temperature lower than the first set temperature; and a temperature detected by the outside air temperature detecting means being equal to or lower than the first set temperature, and
And a second control means 42 for operating the compressor based on the judgment output by the second temperature judgment means 38.
A second pressure setting means 36 for setting a second set pressure higher than the first set pressure; and a pressure detected by the pressure detection means 35 after the operation of the compressor, the pressure being set by the second pressure setting means 36. A second pressure judging means for outputting a judgment output when the following conditions are satisfied.
2 employs a technical means such that the compressor is stopped when the judgment output by the second temperature judgment means 38 and the judgment output by the second pressure judgment means 40 are output.

[0009]

According to the vehicle air conditioner of the present invention having the structure described in claim 1, if the outside air temperature is equal to or higher than the first set temperature (for example, 0 ° C.), the normal set pressure (for example, 0.196 MPa), the refrigerant shortage can be accurately detected, and the outside air temperature is equal to or lower than the first set temperature (eg, 0 ° C.) and equal to or higher than the second set temperature (eg, −5 ° C.). Temporarily activates the compressor, and the detected pressure becomes the second set pressure (for example, 0.
If the pressure is 98 MPa) or more, it is determined that the refrigerant is in an appropriate amount, and the compressor is operated to remove the fog. If the detected pressure is equal to or lower than the second set pressure (for example, 0.98 MPa), it is determined that the refrigerant is insufficient, and the compressor is stopped and protected.

As described above, it is possible to provide an air conditioner for an automobile that can detect the shortage of the refrigerant accurately and operate the compressor even at a low outside air temperature to remove the fogging of the vehicle window glass. .

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The operation will be described with reference to FIG. 3 showing an embodiment of the present invention. FIG. 3 is a schematic view of an automotive air conditioner.
The compressor 10, the condenser 11, the receiver 12, the expansion valve 14, the evaporator 15, and the thermosensitive cylinder 16 constitute an air conditioner, and are driven by the traveling engine 21 through the belt 22 and the clutch 17.

Reference numeral 20 denotes a microcomputer built-in controller (the first and second temperature determining means, the first and second pressure determining means, the first and second controlling means, etc. in the present invention) for controlling the automotive air conditioner. Judgment is made based on various sensor signals such as an outside air sensor 19 and a pressure sensor 13 for detecting an outside air temperature T, an A / C switch signal, and a signal from a setting device, and control of a compressor on / off, a door and a fan (not shown), and a target. Calculation of the blow-out temperature is performed.

Here, the pressure sensor 13 can detect a refrigerant pressure at an arbitrary pressure level as shown in FIG. 5 and can generate a switching signal. The casing of the pressure sensor 13 is formed by engaging a casing upper half 51 and a casing lower half 52 made of synthetic resin, porcelain, metal, or the like, and uniting them. A pressure-sensitive element 50 having a cylindrical shape, which is formed by laminating a piezoelectric element 53 and a piezoelectric element 54 having a diameter smaller than the inner diameter thereof in the respective electrode directions, is mounted inside the casing upper half 51. ing. A piezoelectric element holder 55 is interposed in an annular space formed between the inner peripheral surface of the upper casing half 51 and the pressure-sensitive element 50. Also,
Electrode plates 56, 57 and 58 are respectively joined to the upper and lower portions of the pressure-sensitive element 50 and the contact interface between the two piezoelectric elements, and a terminal 59 for applying a voltage to the piezoelectric element 54 is connected to the electrode plate 57. Terminals 60 for extracting electric signals generated by the piezoelectric element 53 are connected to the plate 56, and grounding terminals 61 are connected to the electrode plate 58. These terminals are mounted on the upper half 51 of the casing. ing. On the other hand, a joint 62 for attachment to a pipe is formed at the lower end of the lower casing half 52. 63 is a packing material for a joint. In addition, a diaphragm 64 for receiving the refrigerant pressure is provided at an opening on the upper surface of the lower casing half 52, and is joined to the lower casing half 52 by a seal member 65.

The pressure sensor 13 having the above structure sends a voltage level proportional to the refrigerant pressure from a terminal 60. Hereinafter, the control operation of the controller 20 will be described with reference to the flowchart of FIG. At the same time as power input, initialization and data reading are performed in step 1. First,
The first set temperature T1 (for example, 0
° C) is set. The first pressure setting means 34 sets a first set pressure P1 (for example, 0.196 MPa). The second temperature setting means 33 sets a second set temperature T2 (for example, -5 ° C.). Also, the second pressure setting means 36 sets the second set pressure P2 (for example, 0.
98 MPa) is set. The determination is made based on various sensor signals including the outside air sensor 19 and the pressure sensor 13, an A / C switch signal, and a signal from a setting device, and controls the ON / OFF of the compressor 10, the control of a door and a fan (not shown), and the target blowout temperature. The calculation is performed, and the process proceeds to step 2.
Here, the outside air sensor 19 is an outside air temperature detecting means 32, and the pressure sensor 13 is a pressure detecting means 35.

Next, proceeding to step 2, the compressor 10
It is determined whether or not an ON (operation) signal is output. Here, if an off (stop) signal is output to the compressor 10, the process proceeds to step 9, where the compressor 10 is turned off and the process returns.
If an ON signal is output to the compressor 10, the process proceeds to step 3. In step 3, the range of the outside air temperature T is determined. The temperature T detected by the outside air sensor 19 is compared with the first set temperature T1 and the second set temperature T2. Here, if the outside air temperature T detected by the outside air sensor 19 is lower than the first set temperature T1 and higher than the second set temperature T2, the process proceeds to Step 4, otherwise proceeds to Step 7. Here, Step 3 constitutes the second temperature determining means 38.

Step 7 is a comparison between the outside air temperature T and the first set temperature T1. Here, when the outside air temperature T is higher than the first set temperature T1 (for example, 0 ° C.), the process proceeds to step 8 to determine the shortage of the refrigerant. If the outside air temperature T is lower than the first set temperature T1 (for example, 0 ° C.), step 3
The temperature is lower than the second set temperature T2 (for example, −5 ° C.), and proceeds to step 9 to prevent the compressor 10 from burning due to freezing of the evaporator 15 and insufficient compressor oil return.
Is turned off and the routine returns. Here, step 7
Constitutes the first temperature determining means 37.

Step 8 is a comparison between the detected pressure P and the first set pressure P1. Here, when the pressure P detected by the pressure sensor 13 is higher than the first set pressure P1, it is determined that a proper amount of the refrigerant is present, the process proceeds to step 6, the compressor 10 is turned on, and the process returns. If the detected pressure P is lower than the first set pressure P1, it is determined that the refrigerant is insufficient, and the routine proceeds to step 9, where the compressor 10 is turned off and the routine returns. Here, when a shortage of the refrigerant is detected, a display unit for displaying the shortage of the refrigerant may be provided on a panel for displaying or operating the air conditioner or near the panel in order to notify the occupant of the detection. As can be seen from the above description, step 8 is the first pressure determining means 39, and steps 7, 8, and 9 constitute the first control means 41.

In step 4, the compressor 10 is forcibly operated, and the flow advances to step 5. Here, if the time t for forcibly operating the compressor 10 is too short, there is a problem that the pressure behavior of the air conditioner is unstable, which leads to erroneous detection. is there. Therefore, in the present embodiment, it is set to 3 to 10 seconds.

Step 5 is a comparison between the detected pressure P and the second set pressure P2. Here, step 5 is the second pressure determining means 40. If the detected pressure P is higher than the second set pressure P2, it is determined that an appropriate amount of refrigerant is present, and the process proceeds to step 6 to turn on the driving means of the compressor 10. To return. Thereby, even when the outside air temperature T is lower than the first set temperature (for example, 0 ° C.), the compressor 10 can be operated, and fogging can be removed. When the detected pressure P is lower than the first set pressure P1,
It is determined that the refrigerant is insufficient, and the routine proceeds to step 9, where the compressor 10 is turned off and the routine returns. As can be seen from the above description, the second control means 42 is constituted by steps 3, 4, 5, and 9.

[Brief description of the drawings]

FIG. 1 is a flowchart showing the operation of the present invention.

FIG. 2 is a characteristic diagram of a conventional pressure switch.

FIG. 3 is a schematic view of a refrigeration cycle control device for a vehicle according to the present invention.

FIG. 4 is a diagram corresponding to claims of the present invention.

FIG. 5 shows a structure of a conventional pressure sensor.

[Explanation of symbols]

 31 first temperature setting means 32 outside air temperature detecting means 33 second temperature setting means 34 first pressure setting means 35 pressure detecting means 36 second pressure setting means 37 first temperature determining means 38 second temperature determining means 39 first pressure determining Means 40 Second pressure determination means 41 First control means 42 Second control means 10 Compressor

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-2-78874 (JP, A) JP-A-3-267657 (JP, A) JP-A-51-8653 (JP, A) JP-A-56- 3862 (JP, A) JP-A-6-194014 (JP, A) JP-A-5-3865 (JP, U) JP-A 1-70070 (JP, U) JP-A 54-114145 (JP, U) JP-B 5-248 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60H 1/32 B60H 3/00 B60S 1/54

Claims (1)

(57) [Claims] 1. An automotive air conditioner having a refrigeration cycle, wherein a first temperature setting means for setting a first set temperature, an outside air temperature detecting means for detecting an outside air temperature, and a temperature detected by the outside air temperature detecting means. First temperature determining means for outputting a determination output when the temperature is equal to or lower than the first set temperature; pressure detecting means for detecting a refrigerant pressure of the refrigeration cycle; first pressure setting means for setting a first set pressure; A first pressure determination unit that outputs a determination output when a pressure detected by the pressure detection unit is equal to or less than the first set pressure; a determination output by the first temperature determination unit and a determination output by the first pressure determination unit First control means for stopping the compressor of the refrigeration cycle when the temperature is output; second temperature setting means for setting a second set temperature lower than the first set temperature; A second temperature determination unit that outputs a determination output when a temperature detected by the air temperature detection unit is equal to or lower than the first set temperature and equal to or higher than the second set temperature; and a determination output by the second temperature determination unit. Second control means for operating the compressor, second pressure setting means for setting a second set pressure higher than the first set pressure, and the pressure detected by the pressure detection means after the operation of the compressor is the second pressure A second pressure determination unit that outputs a determination output when the pressure is equal to or less than a set pressure of the setting unit, wherein the second control unit outputs a determination output by the second temperature determination unit and a determination output by the second pressure determination unit. An automotive air conditioner configured to stop the compressor when the air conditioner stops.