JP2004255990A - Air conditioner for automobile - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an air conditioner for an automobile allowing reduction of cost of a compressor and clutchlessness without lowering operation efficiency of the compressor. <P>SOLUTION: An expansion device 3 with a full-close function to close a flow passage when the variable displacement compressor 1 performs a minimum displacement operation is arranged between a condenser 2 and an evaporator 4. The shutoff of a coolant circulating passage required for preventing freezing in the clutchlessness is performed by the expansion device 3. As a result, a circulating flow passage shutoff function in the variable displacement compressor 1 is not required, and thereby cost can be reduced and the operation efficiency can be improved since pressure loss is eliminated. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an air conditioner for a vehicle, and more particularly to an air conditioner for a vehicle that does not require a clutch for transmitting and shutting off the power of the engine between the engine and the compressor.
[0002]
[Prior art]
A compressor used in a refrigeration cycle of an automotive air conditioner uses an engine as a drive source, and generally transmits the power of the engine to the compressor via a clutch. Since the rotation speed of the engine changes depending on the running state, the compressor driven by the engine cannot perform the rotation speed control. Therefore, in order to obtain an appropriate cooling capacity without being limited by the engine speed, a variable displacement compressor capable of varying the discharge capacity of the refrigerant according to the engine speed is used as the compressor. I have.
[0003]
In general, a variable displacement compressor is configured such that a swinging plate provided with a variable inclination angle is driven by a rotating motion of a rotating shaft in an airtight crank chamber to perform a swinging motion, and the swinging motion of the swinging plate is performed. Thus, the piston reciprocates in a direction parallel to the rotation axis. In this swash plate type variable displacement compressor, the stroke of the piston is determined by the differential pressure between the pressure in the crank chamber applied to the piston and the suction pressure in the suction chamber, the inclination angle of the swing plate is determined, and the The discharge capacity is determined. Therefore, in order to control this discharge capacity, the pressure in the crank chamber may be varied, and the pressure in the crank chamber is variable by controlling the flow rate of the refrigerant introduced from the discharge chamber of the variable displacement compressor into the crank chamber. The refrigerant flow rate is controlled by a capacity control valve.
[0004]
In a conventional variable displacement compressor, for example, a displacement control valve is disposed in an air supply passage provided between the discharge chamber and the crank chamber, and a fixed orifice is provided in an exhaust passage provided between the crank chamber and the suction chamber. Is formed. Here, when the displacement control valve is fully opened to maximize the amount of refrigerant introduced from the discharge chamber to the crank chamber, the tilt angle of the swing plate is minimized and the displacement is minimized.
[0005]
In such a variable displacement compressor, when operating the air conditioner, the clutch is connected to drive the engine of the variable displacement compressor, and when the operation is stopped, the clutch is disengaged to stop the variable displacement compressor. . On the other hand, a so-called clutchless compressor without such a clutch for interrupting the power of the engine is known.
[0006]
In a clutchless compressor, the engine and the compressor are directly connected and the compressor is constantly driven.Therefore, even if the compressor is operated with the variable capacity at a minimum, there is a small amount of refrigerant circulation, and The circulation sometimes caused freezing in the evaporator.
[0007]
For this reason, in the conventional clutchless compressor, the freezing of the evaporator is prevented by stopping the flow of the refrigerant circulating in the refrigeration cycle when the compressor is operated at the minimum variable capacity. To stop the circulation of the refrigerant, an electromagnetic on-off valve is provided on the suction side of the compressor, and the electromagnetic on-off valve is closed to stop the circulation of the refrigerant in the refrigeration cycle.
[0008]
As another method, a check valve (discharge opening / closing valve) is provided on the discharge side of the compressor so that the check valve closes when the discharge capacity decreases and the differential pressure across the check valve decreases. There is one that acts to stop the circulation of the refrigerant in the refrigeration cycle (for example, see Patent Document 1). As a result, when the clutchless compressor is operating at the minimum capacity with the capacity control valve fully opened, the discharge side of the compressor is closed by the check valve, and the refrigerant does not flow toward the condenser. Freezing in the vessel will be prevented.
[0009]
[Patent Document 1]
JP-A-10-205446 (paragraph numbers [0030] and [0038], FIG. 1)
[0010]
[Problems to be solved by the invention]
However, in the conventional clutchless compressor, a check valve is provided on the discharge side of the compressor in order to prevent freezing in the evaporator at the time of the minimum capacity operation. When the refrigerant flow rate is high and the discharge flow rate of the refrigerant is high, the check valve is a factor that increases the pressure loss, so that the operating efficiency of the compressor is reduced.
[0011]
The present invention has been made in view of such a point, and provides an air conditioner for a vehicle that can reduce the cost of a compressor and enable a clutchless operation without reducing the operation efficiency of the compressor. With the goal.
[0012]
[Means for Solving the Problems]
In the present invention, in order to solve the above-mentioned problem, a clutch controlled so as to make the exhaust passage between the crank chamber and the suction chamber smaller or close than the supply passage between the discharge chamber and the crank chamber during the minimum capacity operation. In a vehicle air conditioner equipped with a variable displacement compressor, the expansion device having a fully-closed function for performing throttle expansion of the refrigerant and closing a flow path when the variable displacement compressor operates at a minimum capacity is provided. An air conditioner for a vehicle is provided.
[0013]
According to such an automotive air conditioner, the expansion device that performs the expansion expansion of the refrigerant is configured such that the flow path is closed at the time of the minimum capacity operation of the variable capacity compressor. This eliminates the need for a pressure switch, thereby reducing costs, and reducing the pressure loss at the discharge on-off valve during normal operation, thereby improving operating efficiency.
[0014]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a system diagram showing a refrigeration cycle of an automotive air conditioner according to the present invention.
[0015]
This refrigeration cycle includes a variable capacity compressor 1 for compressing a refrigerant, a condenser 2 for condensing the compressed refrigerant, an expansion device 3 with a fully closed function for adiabatically expanding the condensed refrigerant, and And an evaporator 4 for evaporating.
[0016]
The variable displacement compressor 1 has a rotating shaft 6 to which power is transmitted from an engine (not shown) via a pulley in a hermetically formed crank chamber 5. The state is provided. The swing plate 7 is provided with a plurality of pistons 8 that reciprocate in a direction parallel to the rotation shaft 6. A plate having a suction port and a discharge port is disposed at one end of a cylinder bore accommodating these pistons 8, the suction port communicates with a suction chamber 10 via a suction relief valve 9, and the discharge port is connected to a discharge port. It communicates with the discharge chamber 12 via a relief valve 11. The suction chamber 10 is connected to a pipe from the evaporator 4, and the discharge chamber 12 is connected to a pipe to the condenser 2.
[0017]
Further, in the variable displacement compressor 1 exemplified here, the displacement control valve 13 is disposed in an air supply passage provided between the discharge chamber 12 and the crank chamber 5, and the displacement control valve 13 is disposed between the crank chamber 5 and the suction chamber 10. A fixed orifice 14 is provided in the exhaust passage provided in the circumstance. As a result, the discharge pressure Pd of the discharge chamber 12 is introduced into the crank chamber 5 through the displacement control valve 13, and the pressure Pc in the crank chamber 5 is gradually released from the crank chamber 5 to the suction chamber 10 through the fixed orifice 14. Therefore, by controlling the displacement control valve 13, the pressure Pc in the crank chamber 5 is controlled, and the refrigerant displacement of the variable displacement compressor 1 is controlled.
[0018]
The displacement control valve 13 controls the variable displacement compressor 1 in accordance with the control method. The displacement control valve 13 controls the flow rate of the refrigerant introduced from the discharge chamber 12 into the crank chamber 5 by an externally supplied electric signal, and controls the inside of the crank chamber 5. Is controlled. For example, when the variable displacement compressor 1 is a constant flow control type compressor, the displacement control valve 13 controls the refrigerant discharged from the variable displacement compressor 1 to discharge at a constant flow rate. When the variable displacement compressor 1 is a differential pressure control type compressor, the displacement control valve 13 is configured to control the differential pressure between the discharge pressure Pd and the suction pressure Ps or the difference between the discharge pressure Pd and the pressure Pc in the crank chamber 5. Control the pressure to be constant. Further, when the variable displacement compressor 1 is a compressor of a constant suction pressure control type, the displacement control valve 13 controls the suction pressure Ps of the suction chamber 10 to be constant. Of course, the variable capacity compressor 1 is not limited to the above-described control system, but may be any control system.
[0019]
The expansion device 3 with the fully closed function disposed between the condenser 2 and the evaporator 4 can block the flow path when the refrigerant discharge capacity from the variable capacity compressor 1 is operated at the minimum capacity. It has a flow path closing part which can be formed, and a throttle part which can adiabatically expand the refrigerant. When the expansion device with fully closed function 3 is an electric expansion valve, the flow path closing portion closes the flow path when an electric signal is given, or closes the flow path when the electric signal is cut off. There is. When the expansion device with fully closed function 3 is a mechanical expansion valve, it is closed by a differential pressure between a high pressure and a low pressure when the variable capacity compressor 1 is operating at the minimum discharge capacity as a flow path closing portion. Can be configured with a differential pressure valve. In the case of an electric expansion valve, the size of the flow path of the refrigerant is controlled by an electric signal in the throttle section of the expansion device 3 with the fully closed function, so that the differential pressure between the refrigerant inlet and the refrigerant becomes constant. Or the flow rate is controlled to be constant. In the case of a mechanical expansion valve, control is performed so that the differential pressure between the refrigerant inlet and the outlet becomes a predetermined value.
[0020]
Next, specific configuration examples of the electric and mechanical expansion devices 3 with the fully closed function are shown and described.
FIG. 2 is a longitudinal sectional view showing a configuration example of an electric expansion device with a fully closed function.
[0021]
The expansion device 3 with the fully closed function constitutes a differential pressure control expansion valve suitable for application when the variable displacement compressor 1 is of a constant flow control type. The expansion device 3 with a fully closed function is provided with an inlet port 22 for receiving a high-pressure refrigerant on a side surface of a body 21, and a refrigerant pipe 23 from the condenser 2 is welded thereto. A strainer 24 is arranged in the refrigerant pipe 23 so as to close the flow path. The inlet port 22 is connected to an outlet port 26 via a coolant channel 25. A refrigerant pipe 27 is welded to the outlet port 26. A main valve seat 28 is formed integrally with the body 21 in the middle of the refrigerant passage 25. A main valve body 29 is disposed facing the main valve seat 28 from the upstream side, and forms a main valve together with the main valve seat 28. The main valve body 29 is formed integrally with a piston 30 that forms a room into which the refrigerant is introduced between the main valve body 29 and the main valve seat 28. The piston 30 is disposed so as to be able to advance and retreat in a direction in which the main valve body 29 comes into contact with and separate from the main valve seat 28, and a refrigerant flow path 31 is formed at a center axis position. Is communicated with an orifice 32 drilled from the side. The refrigerant flow path 31 and the orifice 32 constitute a throttle flow path that decompresses the high-pressure refrigerant introduced into the upper chamber of the piston 30 in the figure and guides it to the lower chamber of the piston 30 in the figure. The lower chamber of the piston 30 in the figure is closed by a press-fitting member 33, and a spring 34 for urging the piston 30 in the main valve closing direction is disposed between the piston 30 and the press-fitting member 33. I have. The press-fitting member 33 has its lower end welded to the body 21 after adjusting the load of the spring 34 by the amount of press-fitting.
[0022]
The room formed by the piston 30 and the press-fitting member 33 communicates with the room downstream of the main valve, that is, the room communicating with the outlet port 26, through a refrigerant flow passage 35 formed in the body 21. A pilot valve seat 36 is formed, and a needle-shaped pilot valve body 37 is arranged from the downstream side facing the pilot valve seat 36, and constitutes a pilot valve together with the pilot valve seat 36.
[0023]
A solenoid portion for controlling a pilot valve is provided on an upper portion of the body 21. The solenoid portion includes a sleeve 39 having a lower end fitted in a fitting hole 38 formed in an upper portion of the body 21, a plunger 40 disposed in the sleeve 39 so as to be able to advance and retreat in the axial direction, and a sleeve 39. A cylindrical core 41 fitted to an upper end portion is fixedly disposed through an axial position of the plunger 40, and a lower end portion is supported by a bearing 42 formed on the body 21, and an upper end portion is positioned at an axial position of the core 41. A shaft 44 supported by a bearing 43 press-fitted into an opening formed through the shaft is disposed between the plunger 40 and the bearing 43, and the pilot valve body 37 is attached via the shaft 44 in the valve closing direction. A biasing spring 45, an electromagnetic coil 46 disposed outside the sleeve 39, a yoke 47 formed so as to surround the outside, a yoke 47 and the sleeve 3 And a deployed plate 48. to form a magnetic circuit between the. Here, the spring 45 has a spring force greater than the force by which the pilot valve body 37 is lifted by the differential pressure between the high pressure and the low pressure when the variable capacity compressor 1 is operating at the minimum capacity. I have. After the open end of the core 41 is closed by the press-fitting member 49, the distal ends thereof are sealed by welding. A rubber O-ring 50 is arranged in a space surrounded by the body 21, the sleeve 39, and the plate 48.
[0024]
In the expansion device 3 with the fully closed function configured as described above, first, in the illustrated state where the control current to the electromagnetic coil 46 is 0 and the current is not supplied, when a high-pressure refrigerant is introduced into the inlet port 22, The refrigerant is introduced into a room above the piston 30. This refrigerant is introduced into the lower chamber of the piston 30 through the orifice 32 of the main valve body 29 and the refrigerant flow path 31 of the piston 30, and is further supplied to the pilot valve through the refrigerant flow path 35 formed in the body 21. Is done.
[0025]
When the variable displacement compressor 1 is operating at the minimum displacement, such as when the air conditioner is stopped or the refrigeration load is very small even when the air conditioner is running, the differential pressure across the pilot valve Becomes smaller than the value set by the spring 45. At this time, since the refrigerant pressure in the lower chamber of the piston 30 does not reach the position where the pilot valve body 37 is pushed open, the lower chamber of the piston 30 eventually becomes the same pressure as the upper chamber of the piston 30, and the main valve The body 29 is urged by the spring 34 to maintain a state of being seated on the main valve seat 28, that is, a state where the main valve is fully closed. As a result, the refrigerant discharged from the variable displacement compressor 1 operating at the minimum capacity is stopped from circulating in the expansion device 3 with the fully closed function, and does not flow to the evaporator 4, and therefore, is not evaporated. Freezing in the vessel 4 can be prevented. At this time, since the displacement control valve 13 controls the discharged refrigerant to be introduced into the crank chamber 5 at the maximum flow rate, the discharged refrigerant circulates through the variable displacement compressor 1. Become.
[0026]
Next, when the variable displacement compressor 1 enters the variable displacement range, such as when the air conditioner is started, the differential pressure across the pilot valve exceeds the value set by the spring 45. Then, the refrigerant pressure in the room below the piston 30 pushes and opens the pilot valve body 37 and flows out into the low-pressure room communicating with the outlet port 26. As a result, the pressure in the lower chamber of the piston 30 decreases, so that the piston 30 moves downward in the drawing, the main valve body 29 separates from the main valve seat 28, the main valve opens, and is introduced into the inlet port 22. The refrigerant flows out to the outlet port 26 through the main valve.
[0027]
When the refrigerant pressure on the upstream side of the main valve decreases due to the refrigerant flowing out to the outlet port 26, the pressure of the refrigerant supplied to the pilot valve also decreases, so that the pilot valve body 37 moves in the valve closing direction. As a result, the pressure of the refrigerant introduced into the lower chamber of the piston 30 increases, so that the piston 30 moves upward in the drawing, and accordingly, the main valve body 29 moves in the valve closing direction, and Reduces the flow rate of the refrigerant, so that the refrigerant pressure on the upstream side of the main valve increases. By repeating the above operation, the differential pressure across the main valve is controlled to be constant.
[0028]
Further, when the electromagnetic coil 46 is energized, the plunger 40 is attracted toward the core 41, the spring force of the spring 45 biasing the pilot valve body 37 in the valve closing direction is reduced, and the set differential pressure of the pilot valve is reduced. Make it smaller. When the value of the current supplied to the electromagnetic coil 46 is increased, the attractive force of the plunger 40 to the core 41 is increased, and the differential pressure of the pilot valve, that is, the differential pressure across the differential pressure valve can be set smaller.
[0029]
In this way, the differential pressure control expansion valve controls the refrigerant so that the differential pressure across the main valve becomes a constant value determined by the current supplied to the electromagnetic coil 46. At this time, since the constant flow control type variable displacement compressor 1 controls so that a constant flow rate flows, the differential pressure control type expansion device 3 with the fully closed function competes with the control of the variable displacement compressor 1. Without this, stable control is performed.
[0030]
FIG. 3 is a longitudinal sectional view showing a configuration example of a mechanical expansion device with a fully closed function.
The expansion device 3a with a fully-closed function has a cylindrical body 51 inserted into a refrigerant pipe between the condenser 2 and the evaporator 4, and a left side portion of the expansion device 3a located on the upstream side of the refrigerant flow. Is reduced in diameter and a part of the peripheral side surface is largely opened, and a strainer 52 is fitted into the opening. The body 51 is provided with a step that constitutes the valve seat 53 in the middle of the center refrigerant passage. A valve body 54 is arranged to be able to advance and retreat in the axial direction from the downstream side facing the valve seat 53, and the valve body 54 is urged in a valve closing direction by a spring 55 arranged on the downstream side. . Thus, the valve element 54, the valve seat 53 and the spring 55 constitute a differential pressure valve. An orifice forming member 56 receiving a spring 55 is fitted to the downstream end of the body 51, and an annular orifice 57 communicating with the outside is formed in the orifice forming member 56. Have been. The orifice 57 is formed in an annular shape so as not to penetrate from the outside, and a hole is formed in the refrigerant flow path containing the spring 55 so as to communicate with a part of the annular orifice 57 inside. The fixed orifice has a constant opening area. Thus, the refrigerant in the refrigerant flow path containing the spring 55 is radially discharged from the outer end surface of the orifice forming member 56 via the orifice 57. When the expansion device 3a with the fully closed function is inserted into the refrigerant pipe between the condenser 2 and the evaporator 4 on the outer periphery of the body 51, a rubber O that seals with the refrigerant pipe is provided. A ring 58 is provided.
[0031]
Here, the spring 55 is set to a spring force greater than the force by which the valve body 54 is lifted by the differential pressure between the high pressure and the low pressure when the variable displacement compressor 1 is operating at the minimum displacement. .
[0032]
In the expansion device 3a with the fully closed function having such a configuration, when the variable displacement compressor 1 is operating at the minimum displacement, the differential pressure between the high pressure and the low pressure, that is, the differential pressure across the differential pressure valve is adjusted by the spring 55. It becomes smaller than the set value. For this reason, the valve element 54 is seated on the valve seat 53 by the spring 55 and is kept in the closed state, and the refrigerant is stopped from circulating by the differential pressure valve and does not flow to the evaporator 4. To prevent freezing. At this time, since the displacement control valve 13 controls the discharged refrigerant to be introduced into the crank chamber 5 at the maximum flow rate, the discharged refrigerant circulates through the variable displacement compressor 1. Become.
[0033]
When the variable capacity compressor 1 enters the variable capacity range, the high-pressure refrigerant from the condenser 2 is first introduced to the upstream side of the valve element 54 via the strainer 52. When the differential pressure across the differential pressure valve becomes higher than the value set by the spring 55, the valve element 54 separates from the valve seat 53, the refrigerant flows downstream of the valve seat 53, and further, the annular orifice 57 of the orifice forming member 56. , Where it is throttled and expanded and flows to the evaporator 4. At this time, the valve element 54 controls the flow rate of the refrigerant by the balance between the differential pressure before and after the valve element 54 and the urging force of the spring 55.
[0034]
In the above embodiment, as the variable displacement compressor 1, the displacement control valve 13 is disposed in the air supply passage between the discharge chamber and the crank chamber, and is fixed to the exhaust passage between the crank chamber and the suction chamber. Although an example in which an orifice is arranged has been described, the present invention is not limited to this embodiment. The present invention may be configured so that the exhaust passage is smaller or substantially closed than the air supply passage during the minimum capacity operation.Therefore, a configuration in which a fixed orifice is arranged in the air supply passage and a capacity control valve is arranged in the exhaust passage. Alternatively, a variable displacement compressor having a configuration in which a displacement control valve capable of opening and closing the intake passage and the exhaust passage in conjunction with each other may be arranged.
[0035]
Further, in the above-described embodiment, the case of the differential pressure type expansion valve of the electric control or the mechanical control is shown as an example of the expansion device with the fully closed function, but the proportional valve controlled and driven by the stepping motor, the ON / OFF of the The control valve is not limited to a differential pressure type expansion valve as long as it is a control valve having a function of fully closing at the time of the minimum capacity operation, such as an on / off valve that performs flow control at a time ratio.
[0036]
【The invention's effect】
As described above, in the present invention, the expansion device having the function of fully closing during the minimum capacity operation is used for the device that performs the throttle expansion of the refrigerant so that the refrigerant circulation in the refrigeration cycle can be stopped during the minimum capacity operation. Thus, the variable displacement compressor is made clutchless. This eliminates the need for a discharge opening / closing valve on the discharge side of the variable displacement compressor, thereby reducing the cost of the variable displacement compressor, eliminating pressure loss on the discharge side, and improving operating efficiency. Also, in the case of a differential pressure type expansion valve, the expansion device sets the load of the spring of the mechanism functioning as the differential pressure valve to a value that does not open with the differential pressure between the high pressure and the low pressure during the minimum capacity operation. There is no substantial cost increase.
[Brief description of the drawings]
FIG. 1 is a system diagram showing a refrigeration cycle of an automotive air conditioner according to the present invention.
FIG. 2 is a longitudinal sectional view showing a configuration example of an electric expansion device with a fully closed function.
FIG. 3 is a longitudinal sectional view showing a configuration example of a mechanical expansion device with a fully closed function.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Variable displacement compressor 2 Condenser 3, 3a Expansion device with fully closed function 4 Evaporator 5 Crank chamber 6 Rotary shaft 7 Swing plate 8 Piston 9 Relief valve for suction 10 Suction chamber 11 Relief valve for discharge 12 Discharge chamber 13 Capacity Control valve 14 Fixed orifice 21 Body 22 Inlet port 23 Refrigerant pipe 24 Strainer 25 Refrigerant flow path 26 Outlet port 27 Refrigerant pipe 28 Main valve seat 29 Main valve element 30 Piston 31 Refrigerant flow path 32 Orifice 33 Press-fit member 34 Spring 35 Refrigerant flow path 36 Pilot valve seat 37 Pilot valve body 38 Fitting hole 39 Sleeve 40 Plunger 41 Core 42, 43 Bearing 44 Shaft 45 Spring 46 Electromagnetic coil 47 Yoke 48 Plate 49 Press-in member 50 Rubber O-ring 51 Body 52 Strainer 53 Valve seat 54 Valve body 55 spring 56 orifice forming member 57 Orifice 58 Rubber O-ring Pc Pressure Pd Discharge pressure Ps Suction pressure

Claims (5)

For a vehicle equipped with a clutchless variable displacement compressor that is controlled so that the exhaust passage between the crank chamber and the suction chamber is smaller or closed than the supply passage between the discharge chamber and the crank chamber during the minimum displacement operation. In air conditioners,
An air conditioner for an automobile, which performs expansion expansion of a refrigerant and includes an expansion device with a fully-closed function in which a flow path is closed at the time of a minimum capacity operation of the variable capacity compressor. The automotive air conditioner according to claim 1, wherein the expansion device with a fully closed function is capable of closing the flow passage by electric control. The vehicle air conditioner according to claim 2, wherein the flow path of the expansion device with the fully closed function is closed when the control current is zero. The expansion device with a fully closed function closes when the control current is 0, and opens and throttles at a predetermined differential pressure equal to or higher than the differential pressure between the high pressure and the low pressure during the minimum displacement operation of the variable displacement compressor. The automotive air conditioner according to claim 2, wherein the air conditioner is a differential pressure control type expansion valve that performs expansion. The fully-closed expansion device has a differential pressure valve that opens at a predetermined differential pressure equal to or higher than the differential pressure between the high pressure and the low pressure during the minimum displacement operation of the variable displacement compressor, and when the differential pressure valve is opened. 2. The automotive air conditioner according to claim 1, wherein the expansion valve has an orifice for restricting expansion of the refrigerant.

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