JPH0858357A - Air-conditioner for vehicle - Google Patents

Abstract

PURPOSE: To protect wiring of a motor from overheating by controlling a compressor so as to decrease its rotational speed by a specific rotational speed when a refrigerant delivery pressure of the compressor is increased relating to an upper limit delivery pressure which is the refrigerant delivery pressure corresponding to an upper limit value of refrigerant delivery temperature of the compressor. CONSTITUTION: A compressor 2 of constituting a heat pump cycle is rotated to be driven by a variable speed motor provided integrally with this compressor to be fed with power through an inverter device 11 of a control device 9. In the control device 9, based on a detecting temperature To of an outside air temperature sensor 15, an upper limit delivery pressure Ps corresponding to an upper limit value of delivery temperature of the compressor 2 is calculated. When a detecting pressure Pd of a pressure sensor 13, detecting a delivery pressure of the compressor 2, exceeds the pressure Ps, a compressor rotational speed Nc is decreased by a specific rotational speed ΔN1, to output, in the case of the pressure Pd lower than a command rotational speed No, a control signal of increasing by the specific rotational speed ΔN2 to the inverter device 11.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an air conditioning system for a vehicle which controls an air conditioning in a vehicle by a refrigeration cycle equipped with a compressor which is rotationally driven by a variable speed motor.

[0002]

2. Description of the Related Art For example, in an electric vehicle or the like, a compressor of an air conditioner is usually constructed such that a motor is driven while controlling a rotation speed. In this case, the motor and the compressor are integrated. The structure is common.

By the way, when the compressor is operated at a high speed, the refrigerant in the refrigeration cycle may reach a considerably high temperature. In this case, if the temperature of the refrigerant reaches a high temperature (for example, about 140 ° C.) that exceeds the melting temperature of the coating of the winding of the motor, the insulation may be impaired, so it is necessary to avoid such a situation. There is.

Therefore, conventionally, a structure for detecting the temperature of the refrigerant discharged from the compressor is provided, and when the detected temperature exceeds a preset limit temperature,
It is considered that the number of revolutions of the compressor is controlled to be decreased by a certain level to suppress the temperature rise of the refrigerant.

[0005]

However, in the case of directly detecting the refrigerant discharge temperature of the compressor as in the case of the above-mentioned conventional structure, the heat capacity of the compressor body is controlled even when the rotational speed of the compressor is controlled to decrease. However, in some cases, the temperature cannot be lowered immediately, and in this case, the air conditioning capacity is always lowered by a certain level when the refrigerant discharge temperature is high. There is a problem that it gives an occupant an unpleasant feeling.

The present invention has been made in view of the above circumstances, and an object thereof is to protect the wiring of a motor provided integrally with a compressor from being overheated while the construction is such that the rotational speed of the compressor is not reduced more than necessary. An object of the present invention is to provide a vehicle air conditioner that can be operated.

[0007]

SUMMARY OF THE INVENTION The present invention is directed to an air conditioning system for a vehicle in which a refrigeration cycle including a compressor rotationally driven by a variable speed motor is used to control the air conditioning of the vehicle interior. A pressure detecting means for detecting the refrigerant discharge pressure of the compressor, and a predetermined rotation speed of the compressor when the detected pressure of the pressure detecting means is higher than an upper limit discharge pressure corresponding to an upper limit value of the refrigerant discharge temperature of the compressor. A control means for controlling the air temperature outside the vehicle compartment, and a setting means for changing and setting the upper limit discharge pressure to a high value as the temperature detected by the temperature detecting means rises. It is characterized by being provided and configured.

Further, in the present invention, instead of the temperature detecting means in the above structure, a temperature detecting means for detecting the refrigerant outlet temperature of the outdoor heat exchanger constituting the heat pump cycle may be provided.

Further, when the detected pressure of the pressure detecting means is less than or equal to the upper limit discharge pressure and the rotational speed of the compressor does not reach a target command rotational speed, the control means controls the rotational speed of the compressor. Is preferably controlled so as to be increased by a predetermined number of revolutions.

Then, the setting means may be configured to set an upper limit discharge pressure that continuously changes with respect to a change in the temperature detected by the temperature detecting means.

Alternatively, the setting means may be configured to set an upper limit discharge pressure that changes stepwise with respect to a change in the temperature detected by the temperature detecting means.

[0012]

According to the vehicle air conditioner of the first aspect, when the compressor is driven to rotate by the motor to operate the refrigeration cycle, the control means causes the refrigerant corresponding to the upper limit value of the refrigerant discharge temperature of the compressor. When the refrigerant discharge pressure of the compressor from the pressure detecting means is higher than the upper limit discharge pressure which is the discharge pressure, the rotation speed of the compressor is controlled to be reduced by a predetermined rotation speed. Then, in such a control operation, the setting unit changes and sets the upper limit discharge pressure to increase as the temperature detected by the outdoor temperature detection unit increases.

As a result, the control delay due to the heat capacity can be eliminated as compared with the case of controlling by the refrigerant discharge temperature of the compressor, and the rotation speed of the compressor is reduced corresponding to the upper limit discharge pressure of the compressor which changes according to the outside air temperature. Therefore, it is possible to perform the air conditioning control while suppressing the decrease of the air conditioning capacity as much as possible while performing the protection operation against the overheat of the compressor.

According to the vehicle air conditioner of claim 2,
In place of the outdoor temperature detecting means in the above configuration, a temperature detecting means for detecting the refrigerant outlet temperature of the outdoor heat exchanger is provided,
Since the setting means changes and sets the upper limit discharge pressure of the refrigerant of the compressor according to the refrigerant outlet temperature of the outdoor heat exchanger,
The same effect as described above can be obtained.

According to the vehicle air conditioner of claim 3,
When the pressure detected by the pressure detection means is less than or equal to the upper limit discharge pressure, the control means controls the compressor rotation speed to increase by a predetermined rotation speed when the rotation speed of the compressor does not reach the command rotation speed. It is possible to reliably protect the compressor from overheating while keeping the compressor rotation speed close to the command rotation speed to prevent the air conditioning control performance from deteriorating.

According to the vehicle air conditioner of claim 4,
Since the setting means sets the upper limit discharge pressure so as to continuously change with respect to the change in the temperature detected by the temperature detecting means, the upper limit discharge pressure can be set accurately in accordance with the detected temperature, and the compressor While performing the overheat protection of
Air conditioning capacity can be maximized.

According to the vehicle air conditioner of claim 5,
Since the setting means sets the upper limit discharge pressure so as to change stepwise with respect to the change in the temperature detected by the temperature detecting means, it is possible to easily and quickly set the upper limit discharge pressure following the detected temperature. It can be implemented to increase the air conditioning capacity while protecting the compressor from overheating.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment in which the present invention is applied to an electric vehicle will be described below with reference to FIGS. In FIG. 2 showing the overall schematic configuration, a heat pump cycle 1 as a refrigeration cycle for performing cooling and heating operations in a passenger compartment of an electric vehicle (not shown) is
It is composed of a compressor 2, a four-way valve 3, an outdoor heat exchanger 4, an indoor heat exchanger 5, a pressure reducer 6 and a gas-liquid separator 7, which are connected by a refrigerant flow path. The compressor 2 integrally has a variable speed motor whose rotation speed is variable, and is driven to rotate by being given an AC output of a predetermined frequency by an inverter device 11 described later. In its operating state, The gas refrigerant is sucked and compressed from the gas-liquid separator 7 and discharged as a high-temperature and high-pressure refrigerant to the four-way valve 3 side.

The four-way valve 3 is constructed so as to switch the flow path by an electric drive mechanism, and guides the high temperature and high pressure refrigerant from the compressor 2 to the indoor heat exchanger 5 side and the outdoor heat exchange in the heating operation mode. In the cooling operation mode, a flow path for guiding the low-pressure refrigerant from the cooler 4 to the gas-liquid separator 7 is formed.
The high temperature and high pressure refrigerant from the compressor 2 is transferred to the outdoor heat exchanger 4
It is controlled so as to form a flow path that guides the low-pressure refrigerant from the indoor heat exchanger 5 to the gas-liquid separator 7 while being guided to the side.

The pressure reducer 6 is arranged in the refrigerant flow path between the outdoor heat exchanger 4 and the indoor heat exchanger 5, and adiabatically expands the liquid refrigerant introduced from either one to the other side. It is to be distributed. In addition, a fan device 8 for cooling the refrigerant flowing inside is disposed near the outdoor heat exchanger 4.

Next, the configuration of the control device 9 will be described. The control circuit 10 as the control means and the setting means,
It is composed of a microcomputer, ROM, RAM, etc., and a control program for controlling the rotation speed of the compressor 2 is stored in advance. The inverter circuit 11 converts the DC output of the power supply 12 into an AC output of a predetermined frequency based on a control signal provided from the control circuit 10 and supplies the AC output to the compressor 2. Although not shown, it corresponds to three phases. It is configured such that switching elements such as transistors are bridge-connected.

The pressure sensor 13 as pressure detecting means is
The detection signal is provided on the refrigerant discharge side of the compressor 2, and its detection signal is transmitted via the input circuit 14 of the control device 10 to the control circuit 10
It is designed to be input to. The outside air temperature sensor 15 as an outdoor temperature detecting means is arranged so as to detect the air temperature outside the vehicle, and the detection signal thereof is the input circuit 1
4 is input to the control circuit 10.

Further, a driver's seat portion (not shown) is provided with a rotation speed setting dial 16 for setting a command rotation speed No of the compressor 2, and the setting signal is input to the control circuit 10. Has become. The rotation speed setting dial 16 may have a structure in which a scale corresponding to the set temperature is provided in addition to the structure in which the user directly sets the command rotation speed No.

Next, the operation of this embodiment will be described with reference to FIGS.
Also, referring to FIG. First, when the air conditioning operation is started, the control circuit 10 controls the drive of the compressor 2 so as to perform the air conditioning control according to the set temperature according to an air conditioning operation program (not shown). Accordingly, when the rotation of the compressor 2 is controlled, the heat pump cycle 1 is operated and the air conditioning operation is performed according to either the heating operation mode or the cooling operation mode.

When the heating operation mode is set, the control circuit 10 switches and sets the flow path of the four-way valve 3 as described above (flow path indicated by the solid arrow in FIG. 2), and the compressor 2 The discharged high-temperature and high-pressure refrigerant is guided to the indoor heat exchanger 5, where it exchanges heat with the air introduced into the room to heat the air to heat the passenger compartment, and the refrigerant itself is in a cooled state. Is condensed and flows into the outdoor heat exchanger 4 via the decompressor 6 and is heated by exchanging heat with the outside air so as to flow into the compressor 2 again via the gas-liquid separator 7. Become.

Further, when the cooling operation mode is set, the control circuit 10 switches and sets the flow path of the four-way valve 3 as described above (flow path indicated by a broken arrow in FIG. 2), and the compressor 2 The discharged high-temperature and high-pressure refrigerant is guided to the outdoor heat exchanger 4, where the refrigerant is condensed by exchanging heat with the outside air, and adiabatically expanded through the decompressor 6 to be vaporized to the indoor heat exchanger 5. It is made to flow in, heat-exchange with the air introduced into the vehicle interior to be cooled, and the heated refrigerant is guided to the gas-liquid separator 7 and flowed again into the compressor 2.

The control circuit 10 executes the control program shown in FIG. 1 at an appropriate timing while the air conditioning operation is being performed in this manner. In this case, for example, in the heating operation mode, when the control circuit 10 starts the program,
The detected temperature signal from the outside air temperature sensor 15 is input to the input circuit 14
Is input as the outside air temperature To via (step S1),
The upper limit discharge pressure Ps is calculated based on the value of the outside air temperature To.

In this case, the control circuit 10 controls the outside air temperature To.
The upper limit discharge pressure Ps shown in FIG. 3 is calculated according to the value of the above-mentioned formula according to a previously stored calculation formula (1). Ps = A × To + B (1) where A and B are constants.

This calculation formula (1) is set based on the results of experiments by the inventors, and the relationship between the refrigerant discharge pressure Pd of the compressor 2 and the refrigerant discharge temperature Td is as shown in FIG. It is found that the value is obtained as a correlation using the value of the temperature To as a parameter, and the refrigerant discharge pressure Pd for each outside air temperature To when the refrigerant discharge temperature Td becomes 110 ° C. is set as the upper limit discharge pressure Ps. It is shown in FIG. The control circuit 10 stores the above-described calculation formula (1) and the constants A and B. In step S2, the upper limit discharge pressure Ps is calculated based on the data of the outside air temperature To.

Next, the control circuit 10 sends the detection signal from the pressure sensor 13 via the input circuit 14 to the refrigerant discharge pressure Pd.
(Step S3), and the value is input to step S2
It is determined whether or not the control discharge pressure Ps obtained in step S4 is exceeded (step S4), and if "YES", step S
5, the rotational speed Nc of the compressor 2 is set to a predetermined rotational speed ΔN1 and is controlled to be reduced by, for example, 1000 rpm, and the program is terminated. If “NO”,
The process moves to step S6.

In step S6, the control circuit 10 inputs the value of the command rotation speed No set by the rotation speed setting dial 16, and then in step S7, the value of the current rotation speed Nc of the compressor 2 is input. It comes to calculate. At this time, the control circuit 10 calculates the value of the rotation speed Nc of the compressor 2 according to the following equation (2). Nc (rpm) = [(120 × f) / P] × [1- (X / 100)] (2) where f is the power supply frequency, P is the number of poles of the compressor motor, and X is the slip during rotation ( %) Is shown.

Next, the control circuit 10 judges whether or not the value of the rotation speed Nc of the compressor 2 has reached the command rotation speed No (step S8), and in the case of "NO", terminates the program, In the case of "YES", the process proceeds to step S9 and the value of the rotation speed Nc of the compressor 2 is set to the predetermined rotation speed ΔN.
As 2, the control is performed so as to increase by 100 rpm, and the program is ended.

In the above control, the control program is executed by interrupt processing or the like at a predetermined cycle during the period during which the air conditioning operation control is being executed, and the drive of the compressor 2 is always brought close to the command rotational speed No. While doing
The temperature of the main body of the compressor 2 is prevented from becoming excessively high so as to protect the wiring part and the like from overheating.

According to the present embodiment as described above, the control circuit 1
0, the upper limit discharge pressure Ps corresponding to the upper limit value of the refrigerant discharge temperature of the compressor 2 is obtained based on the temperature detected by the outside air temperature sensor 15, and the refrigerant discharge pressure Pd of the compressor 2 is obtained.
Is higher than the upper limit discharge pressure Ps, the rotation speed Nc of the compressor 2 is decreased by a predetermined rotation speed ΔN1, so that the refrigerant discharge temperature of the compressor 2 is prevented from becoming too high and protection is performed, while the air conditioning capacity is reduced. Can be controlled as much as possible to prevent air-conditioning control from being seriously affected.

Further, according to this embodiment, the compressor 2
When the refrigerant discharge pressure Pd is less than or equal to the upper limit discharge pressure Ps and the rotation speed Nc of the compressor 2 is lower than the command rotation speed Nc, the control circuit 10 causes the predetermined rotation speed ΔN2.
Therefore, the rotation speed Nc of the compressor 2 can always be controlled to approach the command rotation speed No while performing overheat protection of the compressor 2.
It is possible to prevent the reduction of the air conditioning capacity.

FIG. 5 shows a second embodiment of the present invention. The difference from the first embodiment is that the outside air temperature sensor 1
The upper limit discharge pressure Ps for the detection temperature To of No. 5 is just set to be a stepwise value. That is, in the first embodiment, the setting method that changes linearly by calculating the upper limit discharge pressure Ps using the arithmetic expression (1) for the outside air temperature To is set. In this embodiment, for example, the range of the outside air temperature To is divided into the following three areas, and the lower limit discharge pressure Ps is set to the same value in each area.

Region a [−5 ° C. <To ≦ 0 ° C.] ... Upper limit discharge pressure Ps = 12.5 (kg / cm ² ) Region b [0 ° C. <To ≦ 5 ° C.] ... Upper limit discharge pressure Ps = 14.5 (Kg / cm ² ) Area c [5 ° C. <To ≦ 10 ° C.] ... Upper discharge pressure Ps = 17.0 (kg / cm ² ).

According to the second embodiment as described above, the value of the upper limit discharge pressure Ps of the compressor 2 with respect to the outside air temperature To can be set easily and quickly, and is substantially the same as that of the first embodiment. It becomes possible to obtain the same effect.

FIGS. 6 to 9 show the third embodiment of the present invention. The difference from the first embodiment is that the outside air temperature sensor 15 is replaced by the refrigerant outlet temperature T of the outdoor heat exchanger 4.
Refrigerant temperature sensor 17 as temperature detecting means for detecting e
The control circuit 10 controls the upper limit discharge pressure P of the compressor 2 based on the temperature Te detected by the temperature sensor 17.
It has just been configured to set s (see FIG. 7).

FIG. 6 shows a flow chart of the control program. Step S1a is provided in place of the process of step S1 in the first embodiment so that the refrigerant outlet temperature Te of the outdoor heat exchanger 4 is input. What you did is different. In addition, in the process of calculating the upper limit discharge pressure Ps performed in step S2, the following process is performed correspondingly.

That is, the control circuit 10 calculates the upper limit discharge pressure Ps shown in FIG. 8 according to the previously stored calculation formula (3) according to the value of the refrigerant outlet temperature Te of the outdoor heat exchanger 4. Has become. Ps = C × Te + D (3) where C and D are constants.

This equation (3) is set based on the results of experiments by the inventors, and the relationship between the refrigerant discharge pressure Pd of the compressor 2 and the refrigerant discharge temperature Td is shown in FIG. It is found that it is obtained as a correlation using the value of the refrigerant outlet temperature Te of the heat exchanger 4 as a parameter, and the refrigerant discharge pressure Pd of the compressor 2 with respect to each refrigerant outlet temperature Te when the refrigerant discharge temperature Td becomes 110 ° C.
Is set as the upper limit discharge pressure Ps, and this is shown in FIG. The control circuit 10 stores the above calculation formula (3) and constants C and D. In step S2, the upper limit discharge pressure Ps is calculated based on the data of the refrigerant outlet temperature Te of the outdoor heat exchanger 4. Is calculated. Therefore, according to the third embodiment as described above, it is possible to obtain substantially the same effect as that of the first embodiment.

FIG. 10 shows a fourth embodiment of the present invention. The difference from the third embodiment is that the setting of the upper limit discharge pressure Ps with respect to the temperature Te detected by the temperature sensor 17 is a stepwise value. I have just done so. That is, in the third embodiment, the calculation formula (3) is applied to the detected temperature Te.
While the upper limit discharge pressure Ps is calculated by using the above equation, the setting is made to change linearly, whereas in the present embodiment, for example, the range of the detected temperature Te is set to the following three regions. And the lower limit discharge pressure Ps is set to the same value in each region.

Region d [−15 ° C. <Te ≦ −10 ° C.] ... Upper limit discharge pressure Ps = 13.2 (kg / cm ² ) Region e [−10 ° C. <Te ≦ −5 ° C.] ... Upper limit discharge pressure Ps = 14.5 (kg / cm ² ) region f [−5 ° C. <Te ≦ 0 ° C.] ... Upper discharge pressure Ps = 15.7 (kg / cm ² )

According to the fourth embodiment as described above, the value of the upper limit discharge pressure Ps of the compressor 2 with respect to the refrigerant outlet temperature Te of the outdoor heat exchanger 4 can be set easily and quickly, and further, It is possible to obtain substantially the same effect as that of the third embodiment.

The present invention is not limited to the above embodiment, but can be modified or expanded as follows. The rotation speed detection means may directly detect the rotation speed of the compressor. The refrigeration cycle may be a normal refrigeration cycle system other than the heat pump system.

Outside temperature sensor 15 as temperature detecting means
May be provided so as to detect the ambient temperature in the vicinity of the compressor 2.

[Brief description of drawings]

FIG. 1 is a flowchart of a control program showing a first embodiment of the present invention.

FIG. 2 is an overall schematic configuration diagram.

[Fig. 3] Correlation diagram between outdoor air temperature and set pressure

FIG. 4 is a correlation diagram showing experimental results for determining the set pressure with respect to the outdoor air temperature.

FIG. 5 is a view corresponding to FIG. 3 showing a second embodiment of the present invention.

FIG. 6 is a view corresponding to FIG. 1 showing a third embodiment of the present invention.

FIG. 7 is a view corresponding to FIG.

FIG. 8 is a view corresponding to FIG.

FIG. 9 is a view corresponding to FIG.

FIG. 10 is a view corresponding to FIG. 5, showing a fourth embodiment of the present invention.

[Explanation of symbols]

1 is a heat pump system, 2 is a compressor, 3 is a four-way valve, 4 is an outdoor heat exchanger, 5 is an indoor heat exchanger, 6 is a decompressor, 7 is a gas-liquid separator, 8 is a fan device, 9 is a control device,
10 is a control circuit (control means), 11 is an inverter circuit,
12 is a power source, 13 is a pressure sensor (pressure detection means), 14
Is an input circuit, 15 is an outside air temperature sensor (temperature detecting means),
Reference numeral 16 is a rotation speed setting dial, and 17 is a refrigerant temperature sensor (temperature detecting means).

Claims (5)

[Claims] 1. A vehicle air conditioner in which a refrigeration cycle including a compressor rotationally driven by a variable speed motor is used to perform air conditioning control of a vehicle interior, and pressure detection means for detecting a refrigerant discharge pressure of the compressor, When the detected pressure of the pressure detecting means is higher than the upper limit discharge pressure corresponding to the upper limit value of the refrigerant discharge temperature of the compressor, the control means for controlling the number of rotations of the compressor to decrease by a predetermined number of rotations; An air conditioner for a vehicle, comprising: a temperature detecting means for detecting the air temperature of the vehicle; and a setting means for changing and setting the upper limit discharge pressure to a high value as the temperature detected by the temperature detecting means rises. 2. A vehicle air conditioner in which a refrigeration cycle including a compressor rotationally driven by a variable speed motor is used to perform air conditioning control of a vehicle interior, and pressure detection means for detecting a refrigerant discharge pressure of the compressor, When the detected pressure of the pressure detecting means is higher than the upper limit discharge pressure corresponding to the upper limit value of the refrigerant discharge temperature of the compressor, control means for controlling the rotation speed of the compressor to decrease by a predetermined rotation speed, and the heat pump. It is characterized by comprising temperature detecting means for detecting the refrigerant outlet temperature of the outdoor heat exchanger forming the cycle, and setting means for changing the upper limit discharge pressure to a high value as the temperature detected by the temperature detecting means rises. A vehicle air conditioner. 3. The rotation speed of the compressor when the pressure detected by the pressure detection means is equal to or lower than the upper limit discharge pressure and the rotation speed of the compressor does not reach a target command rotation speed. 3. The vehicle air conditioner according to claim 1, wherein the air conditioner is controlled to be increased by a predetermined number of revolutions. 4. The vehicle according to claim 1, wherein the setting unit sets an upper limit discharge pressure that continuously changes with respect to a change in the temperature detected by the temperature detecting unit. Air conditioner. 5. The vehicle according to claim 1, wherein the setting unit sets an upper limit discharge pressure that changes stepwise with respect to a change in the temperature detected by the temperature detecting unit. Air conditioner.