JP2007210443A - Vehicular air conditioner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a vehicular air conditioner capable of restricting the amount of fluctuation of the discharge pressure in response to each of changes in refrigerant flow rate and heat load, preventing deterioration of drivability, and protecting a refrigerating circuit. <P>SOLUTION: The vehicular air conditioner is provided with a compressor 20, a predicting means 52 for predicting a rise of the discharge pressure by detecting the state in which the discharge pressure of CO<SB>2</SB>refrigerant in a compression unit inside the compressor probably rises, and a control means 54 for intermittently connecting a clutch inside the compressor in the case wherein a rise of the discharge pressure is predicted. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention relates to a vehicle air conditioner, and more particularly to a vehicle air conditioner that uses a CO ₂ refrigerant as a refrigerant in a refrigeration circuit.

The compressor of this type of vehicle air conditioner is equipped with a compression unit that performs a series of processes of sucking refrigerant from the evaporator, compressing the refrigerant, and discharging the refrigerant toward the condenser. The refrigerant that has passed through the condenser reaches the evaporator through the expansion valve.
Here, since the discharge pressure of the refrigerant discharged from the compression unit becomes high, it is necessary to protect the high-pressure flow path, specifically, the path from the outlet side of the compressor to the inlet side of the expansion valve. Therefore, a technique is known in which a bypass mechanism communicating with the compressor is provided in the expansion valve, and when the discharge pressure is high, the refrigerant reaching the expansion valve is directed to the compressor without being directed to the evaporator (for example, , See Patent Document 1).
JP 2004-351984 A

By the way, in recent years, in consideration of the global environment, development of a refrigeration cycle using a refrigerant having a small global warming potential has been promoted. An example of this type of refrigerant is natural CO ₂ (carbonic acid) gas.
However, the operating region of the CO ₂ refrigerant is used in the supercritical region in the high-pressure channel, and the CO ₂ refrigerant discharged from the compressor is cooled by the gas cooler but is not liquefied. The fluctuation amount of the discharge pressure becomes very large with respect to each change of the load. Here, although the above-mentioned conventional technology is beneficial in terms of safety, the engine load increases, so there are still problems with respect to the deterioration of the acceleration performance of the vehicle and the occurrence of torque shock.

  The present invention has been made in view of such a problem, and suppresses the fluctuation amount of the discharge pressure with respect to each change in the refrigerant flow rate and the thermal load, prevents the drivability from being deteriorated, and protects the refrigeration circuit. An object of the present invention is to provide a vehicle air conditioner that can be realized.

In order to achieve the above object, the vehicle air conditioner according to claim 1 is a vehicle air conditioner in which the CO ₂ refrigerant circulates in the circulation path of the refrigeration circuit, and is inserted in the circulation path and is disposed in the housing. A rotating shaft that is rotatably supported, a compression unit that is driven by the rotating shaft in the housing and performs a series of refrigerant suction, compression, and discharge processes, and receives power from the engine outside the housing. A compressor provided with a clutch for rotating the rotating shaft, a predicting means for detecting an increase in the discharge pressure of the compression unit and predicting an increase in the discharge pressure, and when an increase in the discharge pressure is predicted And a control means for connecting and disconnecting the clutch.

In the invention according to claim 2, the predicting means detects the execution of the control to turn off the clutch only for a predetermined period when the vehicle is accelerated as the situation where the discharge pressure can increase, and the discharge pressure increases at the end of the control. A signal indicating that the prediction has been made is output to the control means.
Furthermore, in the invention described in claim 3, at least the compressor and the evaporator are inserted in the circulation path in the refrigerant flow direction, and the predicting means is configured so that the discharge pressure can be increased. It is characterized in that execution of control for turning off the clutch only for a predetermined period in order to prevent frost formation is detected, and a signal indicating that an increase in discharge pressure is predicted at the end of the control is output to the control means.

Furthermore, in the invention according to claim 4, the predicting means detects the execution of the control requiring an increase in the thermal load on the refrigeration circuit as a situation where the discharge pressure can increase, and the increase in the discharge pressure is predicted when the control is performed. It is characterized in that a signal to the effect is output to the control means.
Further, in the invention according to claim 5, the predicting means detects the execution of the control requesting an increase in the rotational speed of the engine as a situation where the discharge pressure can be increased, and the increase in the discharge pressure is predicted when the control is performed. It is characterized in that a signal to that effect is output to the control means.

Further, in the invention described in claim 6, the compressor is an internal variable capacity type compressor, and the predicting means detects the on operation of the air conditioner as a situation in which the discharge pressure can rise, Immediately after that, a signal indicating that an increase in the discharge pressure is predicted is output to the control means.
Furthermore, the invention described in claim 7 is characterized in that the control means outputs a signal to the clutch to perform the on operation and the off operation at least twice.

Therefore, according to the vehicle air conditioner of the first aspect of the present invention, the prediction means does not simply detect an increase in the discharge pressure of the compression unit and outputs a signal to the control means. Since a situation in which the pressure can rise is detected in advance and a signal is output to the control means assuming that the discharge pressure has risen, the amount of fluctuation in the discharge pressure can be suppressed.
When an increase in the discharge pressure is predicted, the control means alternately outputs a signal for causing the clutch to perform an on operation and an off operation, thereby coupling the clutch. That is, the intermittent operation of the clutch is performed, and the ON operation is continued while being interrupted from time to time, so that the rise of the discharge pressure is suppressed instantaneously and the amount of fluctuation in the discharge pressure is suppressed. As a result, the deterioration of drivability is reduced and the refrigeration circuit is protected.

  According to the second aspect of the present invention, in order to maintain the acceleration performance of the vehicle, there is a control to turn off the clutch only for a predetermined period when the vehicle is accelerated. growing. Therefore, the predicting means detects the execution of this control in advance as a situation where the discharge pressure can be increased, and presumes that there is an increase in the discharge pressure. Since a signal is output to the control means at the end of this control, the amount of fluctuation in the discharge pressure can be reliably suppressed.

  Further, according to the invention described in claim 3, when the temperature on the outlet side of the evaporator decreases to a predetermined value, there is a control to turn off the clutch for a predetermined period in order to prevent the evaporator from frosting. Even at the end of the control, the fluctuation amount of the discharge pressure becomes large. Therefore, the predicting means detects the execution of this control in advance as a situation where the discharge pressure may increase, presumes that there is an increase in the discharge pressure, and outputs a signal to the control means at the end of this control. Thereby, the fluctuation | variation amount of discharge pressure is suppressed reliably.

Furthermore, according to the fourth aspect of the present invention, the predicting means detects in advance the execution of the control requiring an increase in the heat load on the refrigeration circuit as a situation in which the discharge pressure can be increased, and there is an increase in the discharge pressure. It is pretending to be a thing. And since a signal is output to a control means at the time of this control, the fluctuation amount of discharge pressure is suppressed reliably.
According to the fifth aspect of the present invention, even when control for maintaining the acceleration performance of the vehicle described above or preventing frosting of the evaporator is not performed, control for requesting an increase in the rotational speed of the engine is performed. At the end, the fluctuation amount of the discharge pressure becomes large. Therefore, the prediction means detects the execution of the control requesting an increase in the engine speed in advance as a situation where the discharge pressure can be increased, and presumes that there is an increase in the discharge pressure. Since the signal is output to the means, the fluctuation amount of the discharge pressure is surely suppressed.

  Furthermore, according to the sixth aspect of the invention, even with an internal variable capacity compressor, since the operation with the maximum capacity can be performed immediately after the air conditioner is turned on, the amount of fluctuation in the discharge pressure is large. However, the predicting means detects in advance that the air conditioner is turned on as a situation where the discharge pressure may rise, and presumes that there is an increase in the discharge pressure. Is output, so that the fluctuation amount of the discharge pressure is surely suppressed.

  Furthermore, according to the seventh aspect of the invention, even if the discharge pressure rises in response to the on operation, the discharge pressure immediately decreases due to the off operation, and this operation is repeated, so that the fluctuation amount of the discharge pressure is reliably suppressed.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a front portion of a vehicle, and an engine room 2 is provided in the front portion.
An engine 4 is disposed horizontally in the engine room 2, and a radiator 8 and an electric fan 10 are disposed between the engine 4 and the front grill 6. When the electric fan 10 is driven, outside air is guided into the radiator 8 through the front grill 6, and the cooling water of the engine 4 is cooled by heat exchange in the radiator 8.

The vehicle includes an air conditioner, and the air conditioner has a refrigeration circuit 12. The refrigeration circuit 12 has a path of a CO ₂ refrigerant (hereinafter simply referred to as a refrigerant) that is a natural refrigerant, and the refrigerant can be circulated through the path, and the temperature in the passenger compartment 14 is adjusted to a desired set temperature. To do.
Specifically, a compressor (compressor) 20, a gas cooler 22, an internal heat exchanger 24, an expansion valve 26, an evaporator (evaporator) 28, and an accumulator 29 are sequentially inserted in the path from the upstream side. Further, the compressor 20, the gas cooler 22, the internal heat exchanger 24, the expansion valve 26 and the accumulator 29 are disposed in the engine room 2, and the evaporator 28 is disposed in the instrument panel 18. The panel 18 and the engine room 2 are partitioned by a dash panel 16.

The compressor 20 is a fixed capacity type compressor, and is connected to the engine 4 through a power transmission path 30 and is operated by receiving power from the engine 4. Specifically, the power transmission path 30 includes an output pulley 32 attached to the engine 4 side, a drive pulley 34 attached to the compressor 20 side, and a drive belt 40 wound around the pulleys 32 and 34. Become.
The compressor 20 includes a housing, and a rotating shaft is disposed inside the housing. The rotating shaft is rotatably supported by the housing and has one end protruding from the housing. At one end, an electromagnetic clutch (clutch) 36 is disposed. When the electromagnetic clutch 36 is turned on by turning on the air conditioner, the rotation of the drive pulley 34 is transmitted to the rotating shaft. That is, the electromagnetic clutch 36 receives the power of the engine 4 and rotates the rotating shaft of the compressor 20. On the other hand, when the electromagnetic clutch 36 is turned off, the connection with the drive pulley 34 is released, and the transmission of power from the engine 4 to the rotating shaft is cut off. On the other hand, the other end of the rotating shaft is connected to a compression unit, and this compression unit is driven by the rotation of the rotating shaft, for example, whether it is a piston reciprocating type or a scroll type. Implement the refrigerant suction, compression and discharge process.

  The electromagnetic clutch 36 is turned on and off based on a signal from an electronic control unit (ECU) 50. Specifically, as shown in the figure, the ECU 50 is disposed in the panel 18 and includes a Pd increase prediction unit (prediction unit) 52 and a clutch control unit (control unit) 54. The ECU 50 may be disposed in the vehicle compartment 14 such as under the seat or in the engine room 2.

  The former Pd increase prediction unit 52 detects a situation in which the discharge pressure Pd of the compression unit can increase and predicts an increase in the discharge pressure Pd. If an increase in the discharge pressure Pd is predicted, the latter clutch control is performed. A signal is output to the unit 54. As an example of the situation where the discharge pressure Pd can increase, an acceleration off function is implemented. That is, when there is a request for acceleration of the vehicle, the electromagnetic clutch 36 is turned off for a predetermined period until the engine speed reaches the target value. The Pd increase prediction unit 52 detects that the electromagnetic clutch 36 is turned off by the acceleration-off function as a situation where the discharge pressure can be increased, and predicts an increase in the discharge pressure Pd. Then, at the end of the acceleration-off function, in other words, a signal to the effect that an increase in the discharge pressure Pd is predicted when the acceleration request of the vehicle ends and the electromagnetic clutch 36 is turned on is output to the clutch control unit 54. is doing.

  On the other hand, the clutch control unit 54 normally outputs an operation signal to the electromagnetic clutch 36 in response to various signals from the ECU 50, but when receiving the signal from the Pd increase prediction unit 52, A signal for causing the electromagnetic clutch 36 to intermittently operate is output. Specifically, the on-operation and the off-operation of the electromagnetic clutch 36 are repeated in a short cycle from the end of the vehicle acceleration request. The on operation and the off operation by the intermittent operation are performed at least twice, and the on operation period and the off operation period are about 1 to 2 seconds, respectively. Each of these periods may gradually become longer or shorter with time.

As described above, according to the present embodiment, the Pd increase prediction unit 52 does not simply detect the fact that the discharge pressure Pd of the compression unit has increased and outputs a signal to the electromagnetic clutch 36, but this discharge pressure Pd. Is detected in advance, and a signal is output to the clutch control unit 54 assuming that there is an increase in the discharge pressure Pd.
When an increase in the discharge pressure is predicted, the clutch control unit 54 performs intermittent operation of the electromagnetic clutch 54, and the ON operation is continued while being interrupted from time to time. Thereby, the rise of the discharge pressure Pd is instantaneously suppressed, and a significant fluctuation of the discharge pressure Pd is suppressed.

  More specifically, as shown in FIG. 2, when there is a vehicle acceleration request when the electromagnetic clutch 36 is on, the ECU 50 instructs the engine 4 to increase the engine rotation speed Ne. Simultaneously with the increase of the engine rotational speed Ne, the electromagnetic clutch 36 is turned off (acceleration off function). The Pd increase prediction unit 52 predicts that the discharge operation Pd is increased when the off operation is performed.

  Here, while the discharge pressure Pd continues to decrease as the electromagnetic clutch 36 is turned off, the refrigerant flow rate increases as the engine rotational speed Ne increases. Therefore, when the on-operation of the electromagnetic clutch 36 is continuously performed when the engine speed Ne reaches the target value and the acceleration-off function is released, the discharge pressure Pd is indicated as indicated by the one-dot chain line in the figure. Becomes a very large value.

  However, the Pd increase prediction unit 52 outputs a signal to the clutch control unit 54 when the acceleration off function is released, and the clutch control unit 54 performs an on operation and an off operation on the electromagnetic clutch 36 based on this signal in a short cycle. Repeated about twice. As a result, as indicated by the solid line in the figure, the discharge pressure Pd rises in response to the on operation of the electromagnetic clutch 36, but immediately drops by the subsequent off operation. After that, although it rises again in response to the on operation, it also immediately descends by the off operation, so even if it rises in response to the further on operation, the discharge pressure Pd as shown by the one-dot chain line in the figure. The amount of fluctuation is reliably suppressed.

As a result, the engine load does not increase, the acceleration performance of the vehicle and the torque shock are prevented, and the deterioration of drivability is reduced. Further, the durability of the high-pressure flow paths such as the compressor 20, the gas cooler 22 and the expansion valve 26 due to the temporary increase in the internal pressure in the refrigeration circuit 12 is prevented, thereby contributing to protection of the refrigeration circuit.
By the way, the Pd increase prediction unit 52 is not limited to the acceleration off function described above, and can also be applied to the clutch cycling function.

  Specifically, as shown in FIG. 3, when there is a request to prevent frosting of the evaporator 28 when the electromagnetic clutch 36 is on, an increase in the temperature T on the outlet side of the evaporator 28 is caused by the ECU 50. The electromagnetic clutch 36 is instructed. That is, when the temperature T on the outlet side of the evaporator 28 is lowered to a predetermined value, the electromagnetic clutch 36 is turned off to prevent frosting of the evaporator 28 (clutch cycling function). The Pd increase prediction unit 52 predicts that the discharge operation Pd is increased when the off operation is performed.

  Here, as the electromagnetic clutch 36 is turned off, the temperature T on the outlet side of the evaporator 28 increases, and the discharge pressure Pd continues to decrease. On the other hand, the refrigerant flow rate is collected on the suction side of the compressor 20. Accordingly, when the ON operation of the electromagnetic clutch 36 is continuously performed when the temperature T on the outlet side of the evaporator 28 reaches the target value and the clutch cycling function is released, this is indicated by a one-dot chain line in the figure. Thus, the discharge pressure Pd becomes a very large value.

  However, when the clutch cycling function is released, the Pd increase prediction unit 52 outputs a signal to the clutch control unit 54, and the clutch control unit 54 performs an ON operation and an OFF operation on the electromagnetic clutch 36 based on this signal in a short cycle. As shown by the solid line in the figure, the discharge pressure Pd in this case also rises in response to the ON operation of the electromagnetic clutch 36, but immediately decreases by the subsequent OFF operation, and then turns ON again. Although it rises in response to the operation, it also descends immediately due to the off-operation, so that even if it continues to rise in response to the on-operation, the amount of fluctuation in the discharge pressure Pd as shown by the one-dot chain line in the figure is reliably suppressed. .

The Pd increase prediction unit 52 can also be applied to the case where the functions of acceleration off and clutch cycling described above are not provided.
Specifically, as shown in FIG. 4, even if the electromagnetic clutch 36 is not normally turned off, there is a request for acceleration of the vehicle. For example, the accelerator pedal in the passenger compartment 14 is depressed and the engine rotational speed Ne is set. When there is an increase request, the flow rate of the refrigerant increases as the engine rotational speed Ne increases, and the discharge pressure Pd increases as indicated by the one-dot chain line in the figure as the electromagnetic clutch 36 is continuously turned on. Very large value.

  Here, the Pd increase prediction unit 52 predicts the increase request of the engine rotation speed Ne to increase the discharge pressure Pd. For example, when the negative pressure due to depression of the accelerator pedal increases, a signal is sent to the clutch control unit 54. Is output. Based on this signal, the clutch control unit 54 causes the electromagnetic clutch 36 to repeat the on operation and the off operation about three times in a short cycle. Thereby, as shown by the solid line in the figure, the fluctuation amount of the discharge pressure Pd is surely suppressed as compared with the one-dot chain line in the figure. The Pd increase prediction unit may detect the rise of the discharge pressure Pd by detecting the rise of the discharge pressure Pd in addition to the engine rotation speed Ne.

  Furthermore, the Pd increase prediction unit 52 performs control that requires an increase in the heat load on the refrigeration circuit 12 as a state in which the discharge pressure Pd can increase (for example, the blower air volume is selected from low to high, or from the inside air circulation to the outside air It is also possible to detect the implementation of the air conditioner (which is selected for introduction or the on-operation of the air conditioner is selected), and to predict an increase in the discharge pressure Pd. Then, for example, when the air volume is selected high, the outside air introduction is selected, or the ON operation of the air conditioner is selected, a signal indicating that the increase of the discharge pressure Pd is predicted is output to the clutch control unit 54. When the clutch control unit 54 performs the intermittent operation of the electromagnetic clutch 36, the amount of fluctuation of the discharge pressure Pd can be reliably suppressed even if the thermal load increases.

  The compressor may be an internal variable capacity compressor that keeps the suction pressure constant. In this case, the Pd increase prediction unit 52 detects that the air conditioner is turned on as a situation in which the discharge pressure can increase. This predicts an increase in discharge pressure. Then, a signal indicating that an increase in the discharge pressure Pd is predicted immediately after the air conditioner is turned on is output to the clutch control unit 54 and the electromagnetic clutch 36 is intermittently operated, whereby the variation amount of the discharge pressure Pd is It is surely suppressed. This is because even an internal variable capacity type compressor is operated with the maximum capacity immediately after the air conditioner is turned on, and is considered to be similar to the above-described fixed capacity type compressor.

It is the schematic of the vehicle air conditioner which concerns on one Example of this invention. It is a figure explaining the effect by the vehicle air conditioner of FIG. It is a figure explaining the effect by the vehicle air conditioner of FIG. It is a figure explaining the effect by the vehicle air conditioner of FIG.

Explanation of symbols

4 Engine 12 Refrigeration Circuit 20 Compressor 22 Gas Cooler 26 Expansion Valve 28 Evaporator 36 Electromagnetic Clutch (Clutch)
50 Electronic control unit (ECU)
52 Pd increase prediction unit (prediction means)
54 Clutch control unit (control means)

Claims (7)

A vehicle air conditioner in which a CO ₂ refrigerant circulates in a circulation path of a refrigeration circuit,
A rotation shaft inserted in the circulation path and rotatably supported in the housing, and a compression driven by the rotation shaft in the housing to perform a series of processes of suction, compression and discharge of the refrigerant A compressor including a unit and a clutch that rotates the rotating shaft by receiving power from an engine outside the housing;
A predicting means for detecting an increase in the discharge pressure of the compression unit and predicting an increase in the discharge pressure;
The vehicle air conditioner further comprising a control unit that intermittently connects the clutch when an increase in the discharge pressure is predicted.   The predicting means detects that the clutch is turned off only for a predetermined period during acceleration of the vehicle as a situation where the discharge pressure can be increased, and that the increase in the discharge pressure is predicted at the end of the control. The vehicle air conditioner according to claim 1, wherein a signal is output to the control means. In the circulation path, at least the compressor and the evaporator are inserted in the flow direction of the refrigerant,
The predicting means detects that the clutch is turned off only for a predetermined period to prevent the evaporator from forming frost as a situation where the discharge pressure can be increased, and the discharge pressure increases at the end of the control. The vehicle air conditioner according to claim 1, wherein a signal indicating that the prediction has been made is output to the control means.   The prediction means detects the execution of a control requesting an increase in the thermal load on the refrigeration circuit as a situation where the discharge pressure can increase, and outputs a signal that the increase in the discharge pressure is predicted when the control is performed. The vehicle air conditioner according to claim 1, wherein the vehicle air conditioner outputs to the control means.   The predicting means detects execution of a control requesting an increase in the rotational speed of the engine as a situation where the discharge pressure can be increased, and outputs a signal indicating that the increase in the discharge pressure is predicted when the control is performed. The vehicle air conditioner according to claim 1, wherein the vehicle air conditioner is output to the control means. The compressor is an internal variable capacity compressor,
The predicting unit detects that the air conditioner is turned on as a situation where the discharge pressure can be increased, and outputs a signal to the control unit that the increase in the discharge pressure is predicted immediately after the on operation. The vehicle air conditioner according to claim 1, wherein the vehicle air conditioner is provided.   2. The vehicle air conditioner according to claim 1, wherein the control unit outputs a signal for performing the on operation and the off operation at least twice to the clutch.

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