Vehicle compressor control method

Abstract

To provide a vehicle compressor control method capable of efficiently avoiding pressure abnormality and abnormal heat generation.SOLUTION: A vehicular compressor control method according to the present invention controls a compressor 106 of an air conditioning system 100. The method includes: acquiring a pressure value of a high-pressure refrigerant that, among refrigerants of the air conditioning system 100, flows from a condenser 110 toward an expansion valve 114; acquiring a rotation speed of the compressor 106; performing a first control of stopping the compressor 106 until the refrigerant pressure becomes less than a predetermined first threshold value P1 when the refrigerant pressure is equal to or greater than the first threshold value P1; and performing a second control of stopping the compressor 106 until the refrigerant pressure becomes less than a second threshold value P2 when the refrigerant pressure is equal to or greater than the second threshold value P2 lower than the first threshold value P1 when the compressor rotation speed is equal to or greater than a predetermined value N even when the refrigerant pressure is less than the first threshold value P1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for controlling a compressor for a vehicle. [Background technology]

[0002] Generally, a vehicle's air conditioning system compresses a refrigerant using a compressor connected to a power unit such as an engine, cools the refrigerant in a condenser, and then reduces the pressure using an expansion valve to generate heat of vaporization, thereby providing cool air inside the vehicle.

[0003] When an air conditioning system starts up with an adequate amount of refrigerant, it will not experience excessive refrigerant pressure buildup, even if it is exposed to high outdoor temperatures or high compressor speeds within reasonable limits. However, air conditioning systems may require additional refrigerant, for example, during maintenance after years of use, in response to concerns about insufficient performance. If the system becomes overcharged, it may experience pressure abnormalities when exposed to high outdoor temperatures or high compressor speeds.

[0004] In view of the above, some vehicle air conditioning systems are provided with safety measures using pressure sensors and thermal fuses to protect the equipment from events such as pressure abnormalities.

[0005] Pressure sensors are used, for example, to monitor the pressure in a high-pressure refrigerant line and stop the operation of a compressor when the pressure exceeds a predetermined value. For example, in the technology of Patent Document 1, as described in paragraph 0014, the discharge pressure of compressor 1 detected by discharge pressure detector 4 is used to control compressor 1 together with the compressor rotation speed.

[0006] Thermal fuses are used to detect abnormal heat generation in compressors. When a compressor starts operating, a clutch is connected to a pulley that receives power from the power unit, connecting the pulley and shaft. If abnormal refrigerant pressure increases the load on the shaft, the clutch may slip when it comes into contact with the pulley, causing friction and generating heat. To prevent this, thermal fuses are installed, for example, in the internal mechanism of the pulley. They can fuse when the pulley heats up, cutting off the current within the compressor and stopping it. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 7-32869 Summary of the Invention [Problem to be solved by the invention]

[0008] The inventors have now confirmed that even when there is no abnormality in the refrigerant pressure, there is a region in the high rotation speed range of the compressor where slippage is likely to occur between the pulley and the clutch. Because this region is also prone to abnormal heat generation due to slippage, it is predicted that there is a higher possibility that shutdown processing will be performed by melting a thermal fuse rather than by using a pressure sensor.

[0009] However, although a physical shutdown process using a thermal fuse can reliably stop the compressor, it requires the replacement of parts to restart the air conditioning system, so it is recommended that it be used only as a final safety measure.On the other hand, an electronic shutdown process using a pressure sensor can resume compressor operation once the pressure returns to the normal range, so it is recommended that it be used in preference to a physical shutdown process using a thermal fuse.

[0010] In view of the above, an object of the present invention is to provide a method for controlling a compressor for a vehicle that can efficiently avoid abnormal pressure and abnormal heat generation. [Means for solving the problem]

[0011] In order to solve the above problem, a representative configuration of the vehicle compressor control method according to the present invention is a vehicle compressor control method for controlling a compressor of a vehicle air conditioning system, characterized in that the pressure value of high-pressure refrigerant from the condenser to the expansion valve among the refrigerant of the vehicle air conditioning system is obtained, the rotation speed of the compressor is obtained, and if the pressure value is equal to or greater than a predetermined first threshold, a first control is performed to stop the compressor until the pressure value becomes less than the first threshold, and even if the pressure value is less than the first threshold, if the rotation speed is equal to or greater than a predetermined value, a second control is performed to stop the compressor until the pressure value becomes less than the second threshold if the pressure value is equal to or greater than a second threshold that is lower than the first threshold. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a method for controlling a vehicle compressor that can efficiently avoid abnormal pressure and abnormal heat generation. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle air conditioning system according to an embodiment of the present invention; [Figure 2] FIG. 2 is a diagram illustrating the operation of the compressor of FIG. [Figure 3] 2 is a flowchart showing a process flow of a vehicle compressor control method carried out by the air conditioning system of FIG. 1. [Figure 4] FIG. 4 is a diagram showing a modified example of the processing of the steps in FIG. 3. DETAILED DESCRIPTION OF THE INVENTION

[0014] A vehicle compressor control method according to one embodiment of the present invention is a vehicle compressor control method for controlling a compressor in a vehicle air conditioning system, which is characterized by acquiring a pressure value of high-pressure refrigerant from a condenser among the refrigerants in the vehicle air conditioning system flowing from a condenser to an expansion valve, acquiring the rotation speed of the compressor, and performing a first control to stop the compressor until the pressure value becomes less than the first threshold if the pressure value is equal to or greater than a predetermined first threshold, and performing a second control to stop the compressor until the pressure value becomes less than the second threshold if the rotation speed is equal to or greater than a predetermined value even if the pressure value is less than the first threshold.

[0015] The control method uses the refrigerant pressure value and the compressor rotation speed to control the compressor. First, a first threshold is set as the upper limit of the refrigerant pressure. When the refrigerant pressure exceeds the first threshold, i.e., when a pressure abnormality is detected, the compressor is stopped regardless of the compressor rotation speed. Then, even if no pressure abnormality occurs, when the compressor rotation speed is increasing, a second threshold lower than the first threshold is set as the upper limit of the refrigerant pressure. When the refrigerant pressure exceeds the second threshold, the compressor is stopped.

[0016] It has been found that as the compressor rotation speed increases, slippage between the compressor pulley and the clutch becomes more likely. This slippage can lead to abnormal heat generation due to friction. In the above configuration, in the rotation range where compressor slippage is likely to occur in the relationship between compressor rotation speed and refrigerant pressure, the accuracy of the pressure value is determined based on a second threshold value lower than the first threshold value, making it possible to prevent abnormal heat generation due to slippage.

[0017] As described above, with the above configuration, by electronically controlling the operation of the compressor using the compressor rotation speed and refrigerant pressure, it is possible to efficiently avoid pressure abnormalities and abnormal heat generation without relying on physical stopping processing such as melting a thermal fuse.

[0018] The second control may stop the compressor when a predetermined time has elapsed while the pressure value remains equal to or higher than the second threshold value.

[0019] This configuration makes it possible to accurately determine whether the pressure value is equal to or greater than the second threshold value. It also makes it possible to prevent the compressor from repeatedly turning on and off, thereby enabling the air conditioning system to be operated appropriately.

[0020] The second control may stop the compressor when the number of times the pressure value reaches or exceeds the second threshold value reaches or exceeds a predetermined number within a predetermined time period.

[0021] The above configuration also makes it possible to accurately determine whether the pressure value is equal to or greater than the second threshold value. It also makes it possible to prevent the compressor from repeatedly turning on and off, thereby enabling the air conditioning system to be operated appropriately. [Example]

[0022] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. Dimensions, materials, and other specific values ​​shown in the embodiments are merely examples for facilitating understanding of the invention and do not limit the present invention unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are designated by the same reference numerals to avoid redundant explanation, and elements not directly related to the present invention are not shown.

[0023] 1 is a diagram showing the schematic configuration of a vehicle air conditioning system (hereinafter referred to as air conditioning system 100) according to an embodiment of the present invention. The air conditioning system 100 includes an HVAC (Heating, Ventilation, and Air Conditioning) unit 102 disposed inside the vehicle cabin, and various elements disposed in a power unit installation room where a power unit 104 is installed.

[0024] The HVAC unit 102 is a device that performs heating, cooling, ventilation, and air conditioning, and is provided, for example, in an instrument panel inside the vehicle.

[0025] The power unit 104 is a device that provides power to the vehicle, and can be realized as, for example, an engine or a motor.

[0026] The compressor 106 is a device that compresses the refrigerant from a low-temperature, low-pressure state to a high-temperature, high-pressure state. The compressor 106 receives power from the power unit 104 via a belt 108 and compresses the refrigerant by rotating a rotor inside a housing, for example.

[0027] Condenser 110 is a device that cools the refrigerant sent from compressor 106. Condenser 110 performs heat dissipation processing on the refrigerant, thereby changing the refrigerant from a high-temperature, high-pressure state to a low-temperature, high-pressure state. Condenser 110 has a serpentine pipe through which the refrigerant passes and fins for heat dissipation, and cools the refrigerant by exchanging heat with outside air using fan 112 provided alongside it.

[0028] The expansion valve 114 is a device that reduces the pressure of the low-temperature, high-pressure refrigerant sent from the condenser 110 and expands it to a low-temperature, low-pressure state. The refrigerant that passes through the expansion valve 114 suddenly changes from a high-pressure state to a low-pressure state, which removes thermal energy from the refrigerant and causes its temperature to drop suddenly.

[0029] The evaporator 116 is a device that cools air using a low-temperature, low-pressure refrigerant. The evaporator 116 supplies temperature-adjusted air to the room using a fan (not shown) that is provided alongside the evaporator 116.

[0030] The control unit 118 is an electronic control unit (ECU) having a CPU and the like, and controls the entire air conditioning system 100 including the compressor 106.

[0031] Figure 2 is a diagram showing the operation of the compressor 106 of Figure 1. Figures 2(a) and 2(b) are schematic cross-sectional views of the compressor 106 of Figure 1. Figure 2(a) is a diagram showing the compressor 106 in the OFF state.

[0032] In the compressor 106, a pulley 120 is rotated by a belt 108 sent out from a power unit 104 (see FIG. 1), and the rotational force of the pulley 120 rotates a rotor (not shown) inside a housing 124 via a shaft 122, thereby compressing the refrigerant.

[0033] 2(a), in the compressor 106 in the OFF state, the clutch 126 is in a state of disengagement from the pulley 120. At this time, the pulley 120 and the shaft 122 are not connected, and the pulley 120 rotates freely relative to the shaft 122.

[0034] 2(b) is a diagram showing the ON state of the compressor 106. When the compressor 106 is turned ON, a current flows through the coil 128 inside the pulley 120, generating a magnetic force.

[0035] Clutch 126 is coupled to shaft 122 via leaf spring 130 and the like, and is attracted by the magnetic force generated in coil 128 and connected to pulley 120. When clutch 126 is connected to pulley 120, pulley 120 and shaft 122 are coupled together, causing the rotor and the like in housing 124 to rotate and starting to compress the refrigerant.

[0036] As described above, when the compressor 106 changes from an OFF state to an ON state, the clutch 126, which is stationary, is connected to the pulley 120 rotating on the shaft 122, and in some cases, slippage may occur between the pulley 120 and the clutch 126.

[0037] Figure 2(c) is a graph showing the relationship between compressor rotation speed and refrigerant pressure. The horizontal axis represents compressor rotation speed (rpm) and the vertical axis represents refrigerant pressure (MPa).

[0038] The compressor rotation speed can be obtained directly from the compressor 106, or can be calculated indirectly from the rotation speed of the power unit 104 (see FIG. 1). The rotation speed of the power unit 104 can be obtained, for example, by a crank angle sensor 160 provided in conjunction with the power unit 104. The refrigerant pressure can be obtained by a pressure sensor 162 provided in conjunction with the high-pressure pipe extending from the condenser 110 to the expansion valve 114 in FIG. 1.

[0039] On the vertical axis of Fig. 2(c), if the refrigerant pressure becomes excessively high, in order to protect the equipment, processing to stop the compressor 106 is performed. In Fig. 2(c), this range is called the pressure abnormality determination region.

[0040] The area to the lower right of the pressure abnormality determination area in Figure 2(c) indicates the area where slippage between pulley 120 (see Figure 2(b)) and clutch 126 is likely to occur. In Figure 2(c), this range is called the slip area. The slip area extends to low refrigerant pressures as the compressor rotation speed increases.

[0041] When the pulley 120 (see FIG. 2(b)) and the clutch 126 slip, it takes longer than normal for the pulley 120 and the clutch 126 to go from a disengaged state to an engaged state. This time tends to increase as the compressor rotation speed increases.

[0042] Fig. 3 is a flowchart showing the flow of processing of a vehicle compressor control method carried out by the air conditioning system 100 of Fig. 1. Each processing step of Fig. 3 is mainly performed by the control unit 118 of Fig. 1.

[0043] This control method makes it possible to prevent abnormal refrigerant pressure and abnormal heat generation due to slippage between the pulley 120 and the clutch 126 by stopping the compressor 106 (see FIG. 1) according to the situation.

[0044] First, in step 140, it is determined whether the air conditioning system 100 (see FIG. 1) is ON or OFF, i.e., whether or not there is a request to operate the compressor 106. If the air conditioning system 100 is OFF, it is determined that there is no request to operate the compressor 106, so the determination is NO and the process ends. If the air conditioning system 100 is ON, it is determined that there is a request to operate the compressor 106, so the determination is YES and the process proceeds to step 142.

[0045] In step 142, the control unit 118 (see FIG. 1) determines whether the pressure value of the refrigerant is equal to or greater than a first threshold value P1. The pressure value of the refrigerant is obtained by the pressure sensor 162 in FIG. 1 from the high-pressure refrigerant flowing through the high-pressure pipe from the condenser 110 toward the expansion valve 114. The first threshold value P1 can be set to the refrigerant pressure at the lower limit of the pressure abnormality determination region on the vertical axis in FIG. 2(c).

[0046] If the refrigerant pressure value is equal to or greater than the first threshold value P1 in step 142, it is determined that a pressure abnormality may have occurred, the determination is YES, and processing is performed in step 148 to turn off the compressor 106 (see FIG. 1).

[0047] After step 148, the process returns to step 140, and the series of processes are repeated. This process realizes a first control in which, when the refrigerant pressure value exceeds the first threshold value P1 on the vertical axis of Fig. 2(c) and enters the pressure abnormality determination region, the compressor 106 (see Fig. 1) is stopped until the pressure value becomes less than the first high pressure value P1.

[0048] If the pressure value of the refrigerant is less than the first threshold value P1 in step 142 of FIG.

[0049] In step 144, in order to perform control taking into account the rotation speed of the compressor 106 (FIG. 1), the control unit 118 (see FIG. 1) determines whether the compressor rotation speed is equal to or greater than a predetermined value N. The predetermined value N can be set to the compressor rotation speed at the lower limit of the slip region on the horizontal axis of FIG. 2(c).

[0050] 1 can be obtained by a predetermined sensor provided adjacent to the compressor 106. In addition, since the operation of the compressor 106 is linked to the operation of the power unit 104 via a belt 108, the rotation speed of the compressor 106 can also be calculated from the rotation speed of the power unit 104. For example, the rotation speed of the power unit 104 can be obtained by a crank angle sensor 160 provided adjacent to the power unit 104.

[0051] If the compressor rotation speed is less than the predetermined value N in step 144 of Fig. 3, the determination in step 144 is NO, and the process proceeds to step 150. This means that the refrigerant pressure is not in the pressure abnormality determination region and the compressor rotation speed is not in the slip region in Fig. 2(c). In this case, after turning on the compressor 106 in step 150, the process returns to step 140 and repeats the series of processes.

[0052] If the rotation speed of the compressor is equal to or greater than the predetermined value N in step 144, the determination in step 144 becomes YES, and the process proceeds to step 146. This means that the rotation speed of the compressor is in the slip region on the horizontal axis of FIG. 2(c).

[0053] In step 146, control unit 118 (see FIG. 1) determines whether the refrigerant pressure value is equal to or greater than second threshold value P2. The determination in step 146 is a determination of whether the refrigerant pressure is in the slip region in FIG. 2(c). The second threshold value P2 can be set to the refrigerant pressure at the lower limit of the slip region on the vertical axis of FIG. 2(c). The second threshold value P2 is a value lower than first threshold value P1, which is the lower limit of the pressure abnormality determination region (P1>P2).

[0054] The second threshold value P2 can be set to a value that gradually decreases as the compressor rotation speed increases. The second threshold value P2 can be stored in advance in the control unit 118 (see FIG. 1), or can be calculated from a predetermined relational expression based on the acquired compressor rotation speed.

[0055] 3, if the pressure value is equal to or greater than the second threshold value P2, the determination in step 146 is YES. In this case, it is determined that the compressor rotation speed and refrigerant pressure are in the slip region in FIG. 2(c), and the compressor 106 (see FIG. 1) is turned off in step 152.

[0056] If the pressure value is less than the second threshold value P2 in step 146, the determination in step 146 is NO. In this case, it is determined that the refrigerant pressure is not in the slip region on the vertical axis of FIG. 2(c), and the compressor 106 is turned ON in step 154.

[0057] After step 152 and step 154, the process returns to step 140, and the series of processes are repeated. By these processes, when the compressor rotation speed in step 144 is higher than the predetermined value N, that is, when the compressor rotation speed falls within the slip region on the horizontal axis of FIG. 2(c), the second control is realized, in which the compressor 106 is stopped until the refrigerant pressure value falls below the second threshold value P2, which is the lower limit of the slip region.

[0058] As described above, this control method uses the refrigerant pressure and the compressor rotation speed to control the compressor 106 (see FIG. 1). First, a first threshold value P1 is set as an upper limit of the refrigerant pressure, and when the refrigerant pressure becomes equal to or greater than the first threshold value P1 (YES in step 142), that is, when a pressure abnormality is detected, the first control is to stop the compressor 106 regardless of the compressor rotation speed (step 148).

[0059] Even if no pressure abnormality occurs (NO in step 142), if the compressor rotation speed rises above a predetermined value N (YES in step 144), a second threshold value P2 lower than the first threshold value P1 is adopted as the upper limit of the refrigerant pressure, and as a second control, if the refrigerant pressure becomes equal to or higher than the second threshold value P2 (YES in step 146), the compressor 106 is stopped (step 152).

[0060] It has been found that an increase in the compressor rotation speed makes it more likely that slippage will occur between the pulley 120 and clutch 126 of the compressor 106 (FIG. 2(b)). This slippage can lead to abnormal heat generation due to friction. In this control method, in the rotation range (slip range in FIG. 2(c)) where the compressor 106 is more likely to slip in terms of the relationship between the compressor rotation speed and the refrigerant pressure, the accuracy of the pressure value is determined based on a second threshold value P2 that is lower than the first threshold value P1, making it possible to prevent abnormal heat generation due to slippage.

[0061] As described above, according to the control method of this embodiment, the operation of compressor 106 (see FIG. 1) is electronically controlled using the compressor rotation speed and refrigerant pressure, making it possible to efficiently avoid pressure abnormalities and abnormal heat generation without relying on physical stopping processing by melting a thermal fuse.

[0062] (Variation) Fig. 4 is a diagram showing a modified example of the process of step 146 in Fig. 3. Fig. 4 is a diagram in which the time (S) for determining whether to cut off the air conditioner is added to the vertical axis on the right side of the graph in Fig. 2(c).

[0063] The line segment shown at the bottom of the graph in Fig. 4 indicates the time interval spent for the determination in step 146 in Fig. 3. For example, range R1 represents a range in the compressor rotation speed shown on the horizontal axis where the time interval spent for the determination in step 146 is longer than in other ranges.

[0064] That is, in this modified example, as a second control performed in the slip region, when a predetermined time has passed while the refrigerant pressure value remains equal to or greater than the second threshold value P2 (YES in step 146 in FIG. 3), the compressor 106 is stopped (step 152).

[0065] The above configuration makes it possible to accurately determine whether the refrigerant pressure has reached or exceeded the second threshold P2 and entered the slip region. Furthermore, the above configuration prevents the hunting phenomenon in which the compressor 106 (see FIG. 1) is repeatedly turned on and off, thereby enabling the air conditioning system 100 to be operated appropriately.

[0066] As another variation, as a second control performed in the slip region, it is also possible to stop compressor 106 (step 152) when the number of times the refrigerant pressure value reaches or exceeds second threshold P2 is a predetermined number or more within a predetermined time period (YES in step 146 of FIG. 3). This configuration also makes it possible to accurately determine whether the refrigerant pressure has reached or exceeded second threshold P2 and entered the slip region. This configuration also prevents the hunting phenomenon in which compressor 106 is repeatedly turned on and off, enabling the air conditioning system 100 to operate appropriately.

[0067] In the embodiment and modified examples described above, the compressor 106 (see FIG. 1) can be stopped in the slip region shown in FIGS. 2(c) and 4 (step 152 in FIG. 3). The compressor rotation speed and refrigerant pressure fall into the slip region when the load on the vehicle's power unit 104 is high, such as when the vehicle is traveling uphill or at high speed. In these situations, the embodiment and modified examples described above can reduce the load on the power unit 104 and contribute to improved fuel economy by stopping the compressor 106.

[0068] As a further modification, it is also possible to spend a predetermined time interval for the determination in step 144 in Fig. 3. For example, if it is detected that the amount of refrigerant in the air conditioning system 100 in Fig. 1 is equal to or less than a predetermined value, the load on the compressor 106 increases, which may in turn increase the load on the power unit 104. In this case, if the compressor rotation speed remains equal to or greater than a predetermined value N for a predetermined time (YES in step 144), the determination in step 146 may be omitted and the compressor 106 may be stopped (step 152). This control can reduce the load on the power unit 104 and contribute to improved fuel economy.

[0069] While the preferred embodiments of the present invention have been described above with reference to the accompanying drawings, it goes without saying that the present invention is not limited to these examples. It is clear that those skilled in the art can conceive of various modifications and alterations within the scope of the claims, and it is understood that these modifications and alterations also fall within the technical scope of the present invention. [Industrial Applicability]

[0070] The present invention can be used in a vehicle compressor control method. [Explanation of symbols]

[0071] 100...air conditioning system, 102...HVAC unit, 104...power unit, 106...compressor, 108...belt, 110...condenser, 112...fan, 114...expansion valve, 116...evaporator, 118...control unit, 120...pulley, 122...shaft, 124...casing, 126...clutch, 128...coil, 130...leaf spring, 160...crank angle sensor, 162...pressure sensor

Claims

1. A vehicle compressor control method for controlling a compressor of a vehicle air conditioning system, comprising: a pressure value of a high-pressure refrigerant flowing from a condenser to an expansion valve among the refrigerants of the vehicle air conditioning system is acquired; Obtaining the rotation speed of the compressor; If the pressure value is equal to or greater than a predetermined first threshold, a first control is performed to stop the compressor until the pressure value becomes less than the first threshold; A compressor control method for a vehicle, characterized in that even if the pressure value is less than the first threshold value, when the rotation speed is equal to or greater than a predetermined value, a second control is performed to stop the compressor until the pressure value becomes less than the second threshold value if the pressure value is equal to or greater than a second threshold value that is lower than the first threshold value.

2. 2. The method for controlling a compressor for a vehicle according to claim 1, wherein the second control stops the compressor when a predetermined time has elapsed while the pressure value remains equal to or greater than the second threshold value.

3. 2. The method for controlling a compressor for a vehicle according to claim 1, wherein the second control stops the compressor when the number of times the pressure value becomes equal to or greater than the second threshold value is equal to or greater than a predetermined number within a predetermined time period.

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