Air-conditioning system

#1. Field of the Invention

#The present invention relates to an air-conditioning system or a refrigerant loop with a variable-stroke compressor, wherein the stroke of the compressor is regulated by the inflow of refrigerant medium from a pressure outlet chamber into a drive chamber and/or by the discharge of refrigerant medium from the drive chamber into a suction pressure chamber.

#2. Description of the Related Art

#The foregoing and other features of the present invention will be more readily apparent from the following detailed description and drawing in which:

#FIG. 1 is a schematic of the refrigerant loop of an air-conditioning system according to the present invention.

#FIG. 1 is a schematic representation of a refrigerant loop of an air-conditioning system 1 according to an embodiment of the present invention. A compressor 2 has a valve 4 arranged in the intake or suction area 3 and connecting the latter with a drive chamber 7 of the compressor. The valve 4 is biased toward a closed position by a spring force 5. The valve 4 can be opened by means of a control device 6 such as an electromagnet 6 that counteracts the spring force 5 with an electromagnetically generated force. The electromagnet 6 can be actuated either by a current signal that produces a proportional valve displacement (as is the case with a so-called proportional magnet actuator) or by a pulse-width-modulated signal. The drive chamber 7 is further connected by way of a second valve 8 to a device 11 at the high-pressure outlet side 12 of the compressor 2. Valve 8 is operable independently of valve 4. Valve 8 is biased towards a closed position by a spring force 9 and can be opened by a magnetic device 10 acting against the spring force. The mechanism 11 schematically represents a lubricating device which directs the lubricant contained in the refrigerant from the high-pressure side 12 to the drive chamber 7 of the compressor 2. The lubricating device 11 provides lubrication to the drive chamber 7 in this manner and prevents that larger quantities of the lubricant are carried through the entire refrigerant loop. A pressure sensor 13, arranged on the high-pressure side 12 of the overall air-conditioning system loop, measures the pressure level on the high-pressure side 12 and sends the measurement values to an electronic processing system 14. A pressure sensor 15, arranged on the suction pressure side 3 of the air-conditioning system 1, signals the pressure values of the suction pressure side 3 to the electronic processing system 14. The electronic processing system 14 sends the appropriate control signals over control lines 16 and 17 to the magnetic valve actuators 6 and 10. The drawing further shows the other components of the overall system loop of the air-conditioning- or heat-pump system collectively represented as block 18. Over control line 19, an actual value of a control variable such as the air temperature after the evaporator is entered into the electronic processing system 14. Over control line 20, a target value for the air temperature after the evaporator is entered into the electronic processing system 14. In accordance with the controller strategies that are programmed into the electronic control system, the pressure levels in the drive chamber 7 of the compressor 2 are regulated by way of the valves 4 and 8 in such a manner that all of the control characteristics outlined above under “Summary of the Invention” can be realized as needed in a given situation.

#As a particular advantage of the system according to the present invention, the concept of two independent valves opens up the possibility to use situation-specific control strategies for the operation of the variable-stroke compressor.