Method for controlling an expansion valve and expansion valve, in particular for vehicle air-conditioning systems operated with CO2 as the refrigerant

Abstract

The invention relates to a method for controlling an expansion valve, in particular for vehicle air-conditioning systems operated with CO 2 as the refrigerant, with a valve housing which has a feed opening and a removal opening, with a valve-closing member which closes a valve seat of a passage opening arranged between the feed and removal openings, and with a resetting device which acts in the closing direction of the valve-closing member, an adjusting element, which is assigned to the valve-closing member, on the low-pressure side being activated via a predetermined threshold value as the low pressure rises or as the temperature on the low-pressure side rises and actuates at least one actuating element by means of which a closing force of the resetting device acting on the valve-closing member is reduced such that a passage opening is enlarged or a passage of a bypass valve arranged on the low-pressure side, which passage is arranged parallel to the passage opening, is opened.

1 . Method for controlling an expansion valve, in particular for vehicle air-conditioning systems operated with CO 2  as the refrigerant, with a valve housing which has a feed opening and a removal opening, with a valve-closing member which closes a valve seat of a passage opening arranged between the feed and removal openings, and with a resetting device which acts in the closing direction of the valve-closing member, characterized in that an adjusting element, which is assigned to the valve-closing member, on the low-pressure side is activated via a predetermined threshold value as the low pressure rises or as the temperature on the low-pressure side rises and actuates at least one actuating element by means of which a closing force of the resetting device acting on the valve-closing member is reduced such that a passage opening is enlarged or a passage of a bypass valve arranged on the low-pressure side, which passage is arranged parallel to the passage opening, is opened.  
     
     
         2 . Expansion valve with a valve housing which has a feed opening and a removal opening, with a valve-closing member which closes a valve seat of a passage opening arranged between the feed and removal openings, and with a resetting device acting in the closing direction of the valve-closing member, characterized in that an adjusting element is arranged on the low-pressure side, is assigned to the valve-closing member and is connected to at least one actuating element which acts on a resetting device provided on the valve-closing member, or in that an adjusting element is provided on the low-pressure side and, together with a passage arranged parallel to the passage opening, forms a bypass valve arranged on the low-pressure side.  
     
     
         3 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is activated by low pressure, is designed as a membrane element or expansion bellows and actuates tappets which act on a resetting device on the high-pressure side in order to reduce the closing force of the valve-closing member closing the passage opening.  
     
     
         4 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is activated by low pressure, is designed as a membrane element or expansion bellows and actuates tappets which act on a resetting device on the low-pressure side in order to reduce the closing force of the valve-closing member closing the passage opening.  
     
     
         5 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is actuated by low pressure, comprises an inert gas filling.  
     
     
         6 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is activated as the temperature on the low-pressure side rises, comprises a temperature sensor, which reduces a closing force acting on the low-pressure side on the valve-closing member or acts on the valve-closing member with a spring force acting in the opening direction parallel to the resetting device, the valve-closing member being held in a closed position by a resetting device on the high-pressure side.  
     
     
         7 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is activated as the temperature on the low-pressure side rises, comprises a temperature sensor, which reduces a closing force acting on the low-pressure side on the valve-closing member or acts on the valve-closing member with a spring force acting in the opening direction parallel to the resetting device, the valve-closing member being held in a closed position by a resetting device on the low-pressure side.  
     
     
         8 . Expansion valve according to  claim 2 , characterized in that the adjusting element, which is actuated as the temperature on the low-pressure side is in the form of a shape memory alloy or wax expansion element.  
     
     
         9 . Expansion valve according to  claim 6 , characterized in that the temperature sensor is provided outside the housing and includes the ambient temperature or the temperature of vehicle parts.  
     
     
         10 . Expansion valve according to  claim 7 , characterized in that the temperature sensor is provided outside the housing and includes the ambient temperature or the temperature of vehicle parts.  
     
     
         11 . Expansion valve according to  claim 2 , characterized in that the bypass valve, which is arranged on the low-pressure side and is activated as a function of the low pressure, has a closing member arranged on a bellows or membrane element.  
     
     
         12 . Expansion valve according to  claim 11 , characterized in that the bellows being filled with inert gas.  
     
     
         13 . Expansion valve according to  claim 2 , characterized in that the bypass valve, which is arranged on the low-pressure side and is activated as a function of the temperature, comprises a temperature sensor, which actuates a closing member provided on the passage.  
     
     
         14 . Expansion valve according to  claim 13 , characterized in that the temperature sensor is designed as a bellows filled with a control medium, as a wax expansion element or as a spring element made from a shape memory alloy.  
     
     
         15 . Expansion valve according to  claim 13 , characterized in that the closing member closing the passage is arranged on the high-pressure side and has a closing element acting towards the passage.