JPH11301256A - Air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To previously prevent a compressor from stopping due to overshooting in an air conditioner constituted to control heating capacity by controlling high pressure. SOLUTION: It is assumed that an air conditioner (a refrigerating cycle) is started by an occupant when outside air temperature is not very low (15 deg.C, for instance) and that set temperature is set high (highest temperature 32 deg.C, for instance), and in this case, it is assumed that extremely large saturation pressure (25 kgf/cm<2> G) is computed by an air conditioner control device. On the other hand, it is assumed that upper limit pressure Pcmax (21 kgf/cm<2> , for instance) is determined from a map. In this case, the saturation pressure PC is reset to the upper limit pressure Pcmax lower than its own value.

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 heating an air-conditioned space by heating air with a condenser of a refrigeration cycle, and particularly to a high pressure (refrigerant temperature) of the refrigeration cycle.
To control the heating capacity by controlling the heating capacity.

[0002]

2. Description of the Related Art As an apparatus for controlling a heating capacity by controlling a high pressure as described above, there is an air conditioner for an electric vehicle described in JP-A-7-1954. In this conventional device, first, a target blow-out temperature of conditioned air is calculated based on various types of air-conditioning information (for example, an inside air temperature, an outside air temperature, and a set temperature in a vehicle cabin). Thereafter, a target high pressure of the high pressure is calculated so as to obtain the target blow-out temperature, and the rotation speed of the compressor is controlled so that the actual high pressure becomes the target high pressure.

[0003] Further, although not described in the above conventional apparatus, in such a refrigeration cycle, when the high pressure exceeds a predetermined pressure (abnormal high pressure value), the refrigeration cycle (compressor) is used to protect the refrigeration cycle apparatus. It is well known to employ protection control to stop

[0004]

However, in the above-mentioned conventional apparatus, the outside air temperature is not 0 ° C. or less (hereinafter, referred to as a low temperature) as in winter, but is, for example, 15 ° C. where the outside air temperature is relatively high. In such a case, if the occupant greatly increases the set temperature, the following problem occurs. In other words, when the set temperature is increased, the target high pressure is calculated to be a very high value.However, when the set temperature is increased when the outside air temperature is high, the pressure of the high pressure becomes higher than when the outside air temperature is low. The climb speed is very fast. For this reason, when the outside air temperature is low, the actual high pressure becomes higher than the target high pressure and overshoots, the high pressure becomes an abnormally high value, and the refrigeration cycle (compressor) stops. .

Accordingly, an object of the present invention is to prevent the compressor from stopping due to overshoot of high pressure.

[0006]

In order to achieve the above object, according to the present invention, an upper limit (Pcmax) lower than the predetermined pressure is set in advance to the target high pressure (Pc). (Pcmax) is characterized in that it is set to a lower value as the outside air temperature increases. Thus, since the upper limit of the target high pressure is set to a value lower than the predetermined pressure, even if the actual high pressure becomes larger than the target high pressure due to overshoot, this high pressure is maintained at the predetermined pressure. And it is possible to prevent the refrigeration cycle from stopping. Then, the above-mentioned pressure rising speed increases as the outside air temperature increases, and the actual high pressure tends to overshoot and approach the predetermined pressure. For this reason, in the present invention, the upper limit is set to a lower value as the outside air temperature increases, so that the refrigeration cycle can be prevented from being stopped in accordance with the outside air temperature.

By the way, in the above-mentioned conventional apparatus, even when the refrigerant compressor does not stop at the predetermined pressure, the operation continues in a region exceeding the high pressure necessary for ensuring the heating performance, so that the compressor is more than necessary. There has been a problem that the number of rotations is increased, and power consumption and noise are increased. On the other hand, in the invention of claim 2, in addition to the operation and effect of the invention of claim 1, an upper limit value is provided for the target high-pressure pressure, so that the compressor rotation speed does not increase more than necessary, Power and noise can be reduced.

[0008]

Embodiments of the present invention will be described below. This example is an example in which the air conditioner of the present invention is applied to an electric vehicle air conditioner. FIG. 1 shows an overall configuration diagram of a vehicle air conditioner. The air conditioner includes an air conditioning duct 2 that forms an air flow path into a vehicle compartment, a blower 3 that introduces air into the duct 2 and sends the air into the vehicle compartment, an accumulator-type refrigeration cycle 4, and an air conditioner control device 5.

The transmitter 3 comprises a blower case 3a, a centrifugal fan 3B and a blower motor 3c. The voltage applied to the blower motor 3c is controlled based on a control signal from an air conditioner control device 5 via a motor drive circuit 6. Is done.
Inside air inlets 7 and 8 for introducing vehicle interior air (inside air) and outside air introduction port 9 for introducing outside air (outside air) are formed in the blower case 3a. Inside / outside air switching damper 1 for adjusting the opening ratio with the opening 9
0 is provided. The inside air inlet 8 is always open.

Downstream of the duct 2, a defroster outlet 11 for blowing conditioned air toward the inner surface of the windshield of the vehicle, a face outlet 12 for blowing conditioned air toward the upper body of the occupant, and a lower body of the occupant A foot outlet 13 for blowing conditioned air toward is formed. Each of the air outlets 11 to 13 is selectively opened and closed by an air outlet switching damper (not shown) that operates according to the air outlet mode.

The refrigerating cycle 4 includes a refrigerant compressor 14 for compressing the refrigerant to a high temperature and a high pressure, an outdoor heat exchanger 15, a cooling heat exchanger 18, a heating heat exchanger 19, an accumulator 20, and a four-way valve 21. The refrigerant compressor 14 is driven by a built-in electric motor 100, and forms a compressor unit 22 together with the four-way valve 21 and the accumulator 20. The electric motor 100 is driven by being supplied with electric power from a battery 101 mounted on the vehicle via an inverter 23. The rotation speed of the electric motor 100 is determined and controlled according to the frequency variably controlled by the inverter 23. Therefore, the refrigerant discharge amount and the refrigerant pressure (high pressure) of the refrigerant compressor 14 change according to the rotation speed of the electric motor 100.

The outdoor heat exchanger 15 is disposed outside the duct 2 (outside the vehicle compartment) to exchange heat between the outside air and the refrigerant. It functions as a refrigerant evaporator and functions as a refrigerant condenser during cooling operation. The cooling decompression device 16 decompresses and expands the refrigerant supplied to the cooling heat exchanger 18 during the cooling operation, and uses a capillary tube as a fixed throttle. The heating decompression device 17 decompresses and expands the refrigerant supplied to the outdoor heat exchanger 15 during the heating operation, and uses a capillary tube similarly to the cooling decompression device 16.

The cooling heat exchanger 18 functions as a refrigerant evaporator during cooling operation, and is disposed in the duct 2.
By performing heat exchange between the low-temperature and low-pressure refrigerant decompressed and expanded by the cooling decompression device 16 and air, the cooling heat exchanger 18
Cool the air passing through. The heating heat exchanger 19 functions as a refrigerant condenser during the heating operation. The heating heat exchanger 19 is arranged downstream of the cooling heat exchanger 18 in the air in the duct 2, and is a high-temperature and high-pressure refrigerant compressed by the refrigerant compressor 14. By performing heat exchange between the air and the air, the air passing through the heating heat exchanger 19 is heated.

The accumulator 20 temporarily stores the excess refrigerant in the refrigeration cycle 4 and sends out only the gas-phase refrigerant to prevent the liquid refrigerant from being sucked into the refrigerant compressor 14. The four-way valve 21 cooperates with the solenoid valves 25 and 26 and the check valves 27 and 28 to switch the flow of the refrigerant to realize the cooling operation, the heating operation, and the dehumidifying operation described below. It is. Hereinafter, how the refrigerant flows in the cooling operation, the heating operation, and the dehumidifying operation will be described.

During the cooling operation, the refrigerant discharged from the refrigerant compressor 14 is supplied to the four-way valve 21 → the check valve 27 → the outdoor heat exchanger 1.
The four-way valve 21 and the solenoid valves 25 and 26 are switched so as to flow in the order of 5 → cooling decompression device 16 → cooling heat exchanger 18 → accumulator 20 → refrigerant compressor 14 (Refrigerant flow during cooling operation is shown in FIG. Indicated by a middle arrow C). During the heating operation, the refrigerant discharged from the refrigerant compressor 14 is supplied to the four-way valve 21.
→ Heating heat exchanger 19 → Heating depressurizer 17 → Check valve 2
8 → Outdoor heat exchanger 15 → Solenoid valve 25 → Accumulator 2
0 → the four-way valve 21 so as to flow in the order of the refrigerant compressor 14,
The electromagnetic valves 25 and 26 are switched (the refrigerant flow during the cooling operation is indicated by an arrow C in FIG. 1).

During the dehumidifying operation, the refrigerant discharged from the refrigerant compressor 14 is supplied to the four-way valve 21 → the heat exchanger 19 for heating → the solenoid valve 26 → the check valve 28 → the outdoor heat exchanger 15 → the decompression device 16 for cooling. The four-way valve 21 and the solenoid valve 2 are arranged such that the cooling heat exchanger 18, the accumulator 20, and the refrigerant compressor 14 flow in this order.
5 and 26 are switched (the refrigerant flow during this dehumidifying operation is indicated by an arrow D in FIG. 1).

The air conditioner control device 5 (see FIG. 2) incorporates a microcomputer (not shown), and operates signals output from an air conditioner operation panel 29 and an air conditioning environment (vehicle) from each sensor (detection means) described later. The blower 3, the inverter 23, the outdoor fan 24, the four-way valve 21, the solenoid valve 2
5, 26, electric components such as an actuator (not shown) for driving the inside / outside air switching damper are controlled.

The sensor includes an inside air sensor 30 for detecting the vehicle interior temperature Tr, an outside air sensor 31 for detecting the outside air temperature Tam,
A solar radiation sensor 32 for detecting the amount of solar radiation Ts, and an inlet temperature sensor 3 for detecting a suction air temperature Tin of the heat exchanger 19 for heating.
3. A refrigerant pressure sensor 34 for detecting the refrigerant pressure (high pressure, the discharge pressure of the refrigerant compressor 14) Pc upstream of the heating heat exchanger 19 is provided. The inlet temperature sensor 33 is attached to a refrigerant pipe 35 that connects the refrigerant compressor 14 and the heating heat exchanger 19.

Next, the control of the rotational speed of the refrigerant compressor 14 during heating operation (performed by the air conditioner control device 5), which is a feature of the present invention, will be described with reference to the flowchart of FIG. First, in step S100, the output from each sensor is read. Next, in step S110, based on the set temperature Tset in the vehicle interior set on the air conditioner operation panel 29 and the vehicle interior temperature Tr, the outside air temperature Tam, and the amount of solar radiation Ts read in step S100, the air-conditioning wind is calculated by the following equation 1. The target outlet temperature TAO is calculated.

[0020]

## EQU1 ## TAO = Kset.Tset-Kr.Tr-K
am · Tam−Ks · Ts + C where Kset is a temperature setting gain, Kr is an inside air temperature gain, Kam is an outside air temperature gain, and C is a correction constant. Next, in step S120, based on the target outlet temperature TAO calculated in step S110 and the intake air temperature Tin of the heating heat exchanger 19, the target outlet temperature TAO is calculated from the following equation (2).
Is calculated to obtain the saturated refrigerant temperature Tc.

[0021]

Tc = (TAO−Tin) / φ (V) + Tin Here, φ (V) is a temperature efficiency that varies depending on the air volume V of the conditioned air from the blower 3. (See FIG. 4) indicating the relationship is stored in the microcomputer in advance.

Next, in step S130, the saturated refrigerant temperature Tc and the saturated pressure Tc (condensing pressure of the heating heat exchanger 19)
Has a correlation shown in FIG. 5, and based on this correlation, the saturated refrigerant temperature Tc obtained in step S120 is determined.
(The target high pressure) is calculated.
The data shown in FIG. 5 is stored in the microcomputer in advance. This saturation pressure Pc is determined by the refrigerant compressor 1
Since the pressure loss from 4 to the heat exchanger 19 for heating is small, it can be regarded as substantially the discharge pressure of the refrigerant compressor 14 (the refrigerant pressure Pc detected by the refrigerant pressure sensor 34).

Next, in step S140, it is determined whether or not the saturation pressure Pc is higher than an upper limit pressure (upper limit value) Pcmax. Here, the upper limit pressure Pcmax is preset and stored in the microcomputer. As shown in FIG. 6, the upper limit pressure Pcmax is set to a lower value as the outside temperature Tam increases. Specifically, in this example, when the outside air temperature is −5 ° C. or less, the upper limit pressure Pcmax is 22 kgf / cm ² G
When the outside air temperature is higher than −5 ° C. and up to 20 ° C., the upper limit pressure Pcmax is set to a lower value as the outside air temperature becomes higher. When the outside air temperature is higher than 20 ° C., the upper limit pressure Pcmax is set to be constant at 17 kgf / cm ² G.

In this embodiment, the saturation pressure Pc
When the pressure reaches a predetermined limit pressure (predetermined pressure) PL, the operation of the refrigerant compressor 14 is automatically stopped because the refrigeration cycle 4 may be damaged. FIG. 6 shows the predetermined limit pressure PL (compressor stop pressure). The predetermined limit pressure PL is set to a value higher than the upper limit pressure Pcmax as can be seen from FIG. I have.

If the result of the determination in step S140 is YES, that is, if the saturation pressure Pc is equal to or higher than the upper limit pressure Pcmax, the routine proceeds to step S150, where the saturation pressure Pc
Is set as the upper limit pressure Pcmax, and the process proceeds to step S160. On the other hand, if the determination result in step S140 is NO, the process directly proceeds to step S160, with the saturation pressure Pc being the value calculated in step S120.

In step S160, step S1 is performed.
30 or the saturation pressure P determined in step S150.
c through the inverter 23 so that the electric motor 10
0 is controlled. Next, the flow of steps S130 to S150 will be described in terms of specific operations.

If the outside air temperature is not so low, for example, the outside air temperature is 15 ° C., the occupant starts the air conditioner (refrigeration cycle 4), and the set temperature (Tset) is set to a large value (for example, the maximum temperature is 32 ° C.). ). Then, in this case, it is assumed that a very large saturation pressure Pc (for example, 25 kgf / cm ² G) is calculated in step S. On the other hand, it is assumed that the upper limit pressure Pcmax is determined from the map of FIG. 6 and is, for example, 21 kgf / cm ² G.

In this case, YES is determined in step S140, and the process proceeds to step S150, where the saturation pressure Pc is reset to the upper limit pressure Pcmax lower than itself. In addition to this, the upper limit pressure Pcmax is, as shown in FIG.
Since it is set to a lower value, overshoot occurs and the actual high pressure (the value detected by the sensor 34) becomes the saturation pressure P
Even if it becomes larger than c, it becomes difficult for this high pressure to reach the predetermined limit pressure PL, and the refrigeration cycle 4 can be prevented from being stopped.

Then, the above-mentioned pressure rising speed becomes higher as the outside air temperature becomes higher, and the actual high pressure (the value detected by the sensor 34) overshoots and tends to approach the predetermined limit pressure PL. Thus, in this example, the higher the outside air temperature, the lower the upper limit pressure Pcmax is set to a lower value.
The refrigeration cycle 4 can be prevented from being stopped in accordance with the outside air temperature.

In the above-described conventional apparatus, the refrigerant compressor 14
Even if it does not come to a stop due to the predetermined limit pressure PL, the operation continues in a region exceeding the high pressure necessary for ensuring the heating performance, the compressor rotation speed becomes higher than necessary, and power consumption and noise are reduced. There was a problem of increasing. On the other hand, in this example, in such a case, the saturation pressure Pc is reset to a small value, so that the compressor speed does not increase unnecessarily, and power consumption and noise can be reduced.

The present invention can be applied not only to an air conditioner for an electric vehicle, but also to an air conditioner for a vehicle that uses a running engine as a compressor, and can be applied to an air conditioner for home and business use. It is.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of an air conditioner according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a control system of the air conditioner in the embodiment.

FIG. 3 is a flowchart showing control contents of a control device in the embodiment.

FIG. 4 is a diagram illustrating a relationship between an air volume and a temperature efficiency in the embodiment.

FIG. 5 is a diagram illustrating a relationship between a saturation temperature and a target pressure in the embodiment.

FIG. 6 is a diagram illustrating a relationship between an outside air temperature and an upper limit pressure in the embodiment.

[Explanation of symbols]

 2 air conditioning duct 4 refrigeration cycle 5 air conditioner control device, 14 refrigerant compressor 19 heat exchanger for heating.

Claims (2)

[Claims] 1. A refrigerant compressor (14) for compressing at least a refrigerant to a high temperature and a high pressure, heat exchange between the high temperature and high pressure refrigerant from the refrigerant compressor (14) and conditioned air, and heating the conditioned air. A refrigeration cycle (4) having a heat exchanger (19); target temperature calculation means (S110) for calculating a target outlet temperature (TAO) of the conditioned air based on air conditioning information affecting an air conditioning environment; A target pressure calculating means (S130) for calculating a target high-pressure pressure (Pc) of the refrigeration cycle (4) based on a target outlet temperature (TAO); and a high-pressure pressure of the refrigeration cycle (4). ), A rotation speed control means (S160) for controlling the rotation speed of the refrigerant compressor (14) so that the high pressure of the refrigeration cycle (4) is a predetermined pressure (PL).
An air conditioner configured to stop the operation of the refrigerant compressor (14) to protect the refrigeration cycle (4) when the pressure becomes higher, wherein the target high pressure (Pc) is lower than the predetermined pressure. An upper limit (Pcmax) is set in advance, and the upper limit (Pcmax) is set.
x) is an air conditioner characterized by being set to a lower value as the outside air temperature increases. 2. An air conditioning duct (2) forming an air flow path into a vehicle cabin, and a refrigerant compressor driven by at least electric power from a battery (101) mounted on the vehicle to compress the refrigerant to a high temperature and a high pressure. 14) and a heating heat exchanger that is disposed in the air conditioning duct (2), exchanges heat between high-temperature and high-pressure refrigerant from the refrigerant compressor (14) and conditioned air, and heats the conditioned air. Based on the refrigeration cycle (4) and the air conditioning information that affects the air conditioning environment in the cabin,
A target temperature calculating means (S110) for calculating a target outlet temperature (TAO) of the conditioned air; and a target pressure for calculating a target high pressure (Pc) of the refrigeration cycle (4) based on the target outlet temperature (TAO). Calculation means (S130); and rotation speed control means (S160) for controlling the rotation speed of the refrigerant compressor (14) such that the high pressure of the refrigeration cycle (4) becomes the target high pressure (Pc). The high pressure of the refrigeration cycle (4) is a predetermined pressure (PL)
When the pressure becomes higher, the vehicle air conditioner is configured to stop the operation of the compressor (14) to protect the refrigeration cycle (4), wherein the target high pressure (Pc) is higher than the predetermined pressure. A low upper limit (Pcmax) is set in advance, and this upper limit (Pcmax) is set.
x) The vehicle air conditioner, wherein the lower the value, the higher the outside air temperature.