Abstract:
A valve mechanism for an air condition circuit of an air condition system may include a valve housing enclosing a fluid duct for passing a fluid flow, a closure body arranged movably in the fluid duct between at least a closed position and an open position, and adjustment element operably connected to the closure body to move the closure body between the open position and the closed position, and a noise reduction device configured to facilitate a reduction of an operating noise when the fluid flow through the fluid duct. The noise reduction device may be disposed at one or more of the closure body, a valve seat, and the adjustment element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to German Patent Application No. DE 10 2015 221 002.2, filed Oct. 27, 2015, the contents of which are hereby incorporated by reference in its entirety. 
       TECHNICAL FIELD 
       [0002]    The invention concerns a valve mechanism, especially an expansion valve, for an air conditioning circuit of an air conditioning system, as well as an air conditioning system with such a valve mechanism. 
       BACKGROUND 
       [0003]    Valve mechanisms which are used as expansion valves in air conditioning systems are known in a variety of forms from the prior art. 
         [0004]    The problem with such expansion valves is often that coherent vibrations can be produced when a refrigerant flows through the valve opening in the flow of refrigerant, resulting in an unwanted noise production in the valve mechanism. 
         [0005]    Given this background, EP 1764 568 A1 discusses a valve mechanism with turbulence generating elements which ensure a turbulent flow of refrigerant at the valve opening. This is supposed to prevent gas bubbles in the liquid refrigerant for the most part or even entirely, so that the flow noise generated when passing through the valve opening should be lessened and homogenized. 
       SUMMARY 
       [0006]    One problem which the present invention proposes to solve is to create an improved design for a valve mechanism which is distinguished in particular by a reduced operating noise. 
         [0007]    This problem is solved by the subject matter of the independent patent claims. Preferred embodiments are the subject matter of the dependent patent claims. 
         [0008]    Accordingly, the basic notion of the invention is to outfit a valve mechanism in the region of its valve opening closable by a closure body with a noise reduction device. The installation of such a noise reduction device in the region of the valve opening means that vibrations occurring there in the closure body and in the adjustment element for moving the closure body, which subsequently lead to said noise production, can be significantly reduced or even entirely prevented. As a result, such a vibration reduction also leads to a lessening of said noise production. 
         [0009]    A valve mechanism according to the invention, especially an expansion valve, for an air conditioning circuit of an air conditioning system comprises a valve housing, which encloses a fluid duct through which a fluid can flow, especially a coolant or refrigerant. In the fluid duct there is arranged a closure body which can move relative to the valve housing. In a closed position, the closure body closes a valve opening present in the fluid duct and enclosed by a valve seat and bears against the valve seat for this purpose. Said valve opening with suitable dimensioning of the fluid duct, especially with reduced diameter in the region of the valve opening, can form an expansion valve together with the valve seat and the closure body. In an open position, the closure body is arranged to release the valve opening at a distance from the valve seat. By means of an adjustment element, the closure body can be moved between the open position and the closed position. For this, the adjustment element can be connected to a suitable driving device, especially an electric, hydraulic or pneumatic actuator for its drive. 
         [0010]    According to the invention, a noise reduction device is configured at the closure body and/or at the valve seat and/or at the adjustment element, and accomplishes a reduction of the operating noise of the valve mechanism when the fluid flows through it. 
         [0011]    Advisedly, the closure body can be designed as a closure ball. Alternatively or additionally, the adjustment element can be designed as a control tappet. Both measures, alone or in combination, facilitate a technical realization of the valve mechanism as an expansion valve with reduced fluid duct diameter in the region of the valve opening. 
         [0012]    In a preferred embodiment, the noise reduction device is designed as a surface structure with a plurality of elevations protruding into the fluid duct. Alternatively or additionally, the surface structure has a plurality of depressions arranged on the surface. In one preferred variant, said elevations and depressions can be arranged in the same surface structure, especially preferably alternating next to each other. The mentioned steps, alone or in combination, accomplish an especially pronounced reduction of the operating noise generated by the valve mechanism. 
         [0013]    According to an advantageous modification, the individual elevations have a height of at most 1 mm, preferably at most 0.2 mm, especially preferably a height of essentially 0.1 mm. Experimental investigations have shown that elevations with such a height provide an especially good reduction of the operating noise of the valve mechanism. 
         [0014]    According to another advantageous modification, the individual depressions have a depth of at most 1 mm, preferably at most 0.2 mm, especially preferably a depth of essentially 0.05 mm. Experimental investigations have shown that depressions with such a depth provide an especially good reduction of the operating noise of the valve mechanism. 
         [0015]    In another advantageous modification, the surface structure has a lateral extension between 0.1 mm 2  and 1 mm 2 . Experimental investigations have shown that a lateral extension of the surface structures in the mentioned range is associated with an especially good reduction of the operating noise of the valve mechanism. 
         [0016]    According to an advantageous modification of the invention, the surface structure is arranged in an axial end section of the adjustment element facing the closure body, on its circumferential side. This measure as well assists the desired noise reduction. 
         [0017]    Moreover, simulation calculations have shown surprisingly that an additional noise reduction can be achieved when the surface structures essential to the invention are designed on both the valve seat and the adjustment element, and such that the two surface structures are positioned opposite each other. In this scenario, the fluid duct through which the fluid flows is therefore enclosed on both sides by the surface structure essential to the invention, so that an especially pronounced dampening effect can be achieved. 
         [0018]    In another preferred embodiment, the surface structure of the closure body is arranged at least partly in a surface region which touches the valve seat in the closed position of the closure body. 
         [0019]    In another preferred embodiment, which can be combined with the above explained preferred embodiment, the surface structure of the valve seat is arranged at least partly in a surface region which touches the closure body in the closed position of the closure body. 
         [0020]    In another preferred embodiment, the valve seat comprises a first seat section in a longitudinal cross section along a movement direction of the adjustment element that passes into a second seat section in the movement direction. In the second seat section, the valve seat tapers, especially in conical manner, away from the first seat section to produce the valve mechanism as an expansion valve. The closure body in the closed position bears against the second seat section, and the second seat section passes along the movement direction into a third seat section. In this variant, the surface structure is configured on at least one of the three seat sections on an internal circumferential side enclosing the fluid duct. Especially preferably, the diameter of the fluid duct is substantially constant in the first and third seat sections. 
         [0021]    Laboratory investigations have further shown that an especially good noise reduction can be achieved when said surface structure of the noise reduction device is realized as a kind of a roughened surface. 
         [0022]    The effect of noise reduction by the noise reduction device can be realized in especially pronounced form if the roughened surface has a roughness Rz of more than 16 μm. 
         [0023]    According to an advantageous modification, the surface structure is formed as a ring or a ring segment and extends around the surface of the closure body along a direction perpendicular to the movement direction. Preferably, the surface structure runs entirely around it. 
         [0024]    To improve the sealing effect of the closure element in its closed position, in another preferred embodiment it is proposed that no surface structure is formed in a surface section of the closure body bearing against the valve seat in the closed position of the closure body. The same effect of an improved sealing action can be achieved by having no surface structure formed in a surface section of the valve seat against which the closure body bears in its closed position. 
         [0025]    In another preferred embodiment, the plurality of elevations and/or depressions is arranged gridlike on the surface. In an equally preferred alternative embodiment, the plurality of elevations and/or depressions is distributed irregularly on the surface. Both variants, which can also be combined, accomplish an especially effective noise dampening. 
         [0026]    Advisedly, the elevations and/or depressions can be formed in substantially round or substantially elongate form in a top view of the surface structure. This measure accomplishes an especially pronounced noise reduction. 
         [0027]    Especially advisedly, the depressions can be formed as craters or funnels. This measure also accomplishes an especially pronounced noise reduction. 
         [0028]    The invention furthermore concerns an air conditioning system, especially for a motor vehicle. The air conditioning system comprises an air conditioning circuit, in which a previously explained valve mechanism is arranged. Thus, the benefits of the valve mechanism according to the invention are transferred to the air conditioning system according to the invention. 
         [0029]    Further important features and benefits of the invention will emerge from the subclaims, the drawings, and the corresponding description of the figures with the aid of the drawings. 
         [0030]    Of course, the above mentioned features and those yet to be mentioned can be used not only in the particular indicated combination, but also in other combinations or alone, without leaving the scope of the present invention. 
         [0031]    Preferred exemplary embodiments of the invention are represented in the drawings and shall be explained more closely in the following description, where the same reference numbers pertain to the same or similar or functionally equivalent components. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]    In the figures, each time schematically, 
           [0033]      FIG. 1  shows an example of a valve mechanism according to the invention in a longitudinal cross section, 
           [0034]      FIG. 2  shows a detail representation of  FIG. 1  with the valve closed, 
           [0035]      FIG. 3  shows a detail representation of  FIG. 1  with the valve opened, 
           [0036]      FIG. 4  shows a detail representation of  FIG. 1 , in which the noise reduction device essential to the invention is shown, 
           [0037]      FIG. 5  shows a representation showing possible configurations of the surface structure forming the noise reduction device. 
       
    
    
     DETAILED DESCRIPTION 
       [0038]      FIG. 1  shows an example of a valve mechanism  1  according to the invention, which can be used as an expansion valve for an air conditioning system, in a longitudinal cross section. The valve mechanism  1  comprises a valve housing  2 , which encloses a fluid duct  3  through which a fluid  4  can flow. In the valve housing  2  there is present a fluid inlet  23 , through which the fluid  4 , typically a coolant or refrigerant of the air conditioning system, can be introduced into the fluid duct  3 . Through a fluid outlet  24  provided on the valve housing  2  the fluid  4  is taken out from the fluid duct  3  once again. 
         [0039]    In the valve housing  2  or in the fluid duct  3  there is formed a valve seat  5 , which encloses a valve opening  8 . In the fluid duct  3 , moreover, there is arranged a closure body  6  which can move relative to the valve housing  2 , being preferably designed as a closure ball  7 . The closure body  6  or the closure ball  7  can be moved between a closed position and an open position. In the closed position, the closure body  6  bears against the valve seat  5  for the closing of the valve opening  8 , so that no fluid  4  can flow through the valve opening  8 . This situation is shown for clarity in a separate representation in  FIG. 3 . 
         [0040]    In the open position, the closure body  6  releases the valve opening  8  for the fluid  4  to flow through and for this it is arranged at a distance from the valve seat  5 . This situation is shown for clarity in a separate representation in  FIG. 2 . 
         [0041]    The moving of the closure body  6  between the open position and the closed position is performed with the aid of an adjustment element  9 , which can be designed as a control tappet  10 . The adjustment element  9  can move along a movement direction V in the fluid duct  3 , which can be a main flow direction H of the fluid  4  flowing through the valve opening  8 . The movement direction V can be identical to a longitudinal direction L of the fluid duct  3 . The adjustment element  9 , in turn, can be connected to a pneumatic or hydraulic or electrical actuator (not shown in the figures) for its drive. The adjustment element  9  moves the closure body  6  by mechanical contact between the open position and the closed position. The closure body  6  can be biased by means of a tensioning element  11 , such as a kind of elastic spring element, against the adjustment element  9 . In the example of  FIG. 1 , the tensioning element  11  also biases the adjustment element  9  against the valve seat  5  and thus toward its closed position. 
         [0042]    The valve mechanism  1  moreover comprises a noise reduction device  12 , by means of which noises, especially vibration-like noises which are generated by vibrations of the closure body  7  as well as the adjustment element  9  when the fluid  4  flows through the valve opening  8 , are dampened. From  FIG. 4 , which shows the valve mechanism in analogous manner to  FIG. 2  in a detail representation in the region of the valve opening  8 , it can be observed that the noise reduction device  12  can be formed on the closure body  6  and/or on the valve seat  5  and/or on the control tappet  10 . In all three cases, the noise reduction device  12  is designed as a surface structure  13   a ,  13   b ,  13   c  with a plurality of elevations  14  and, alternatively or additionally, with a plurality of depressions  25 . 
         [0043]    For clarity,  FIG. 5  shows in addition to the representation of  FIG. 4  a top view of the valve seat  5  along the movement direction V of the adjustment element  9 . As an example, three different surface structures  13   b  are shown: the surface structure  13   b  additionally designated as  15  comprises a plurality of elevations  14 , which are arranged in a grid on the surface  16  of the valve seat  5  and protrude from the surface  16  into the fluid duct  3 . The plurality of elevations  14  can, however, also be distributed irregularly on the surface  16 , as is shown for example for the surface structure  13   b  additionally designated as  18 . The elevations  14  can be elongate or round (not shown) in configuration, as shown for the surface structure  15 . 
         [0044]    However, in place of irregularly arranged elevations  14 , there can also be depressions  25  arranged irregularly on the surface  16 , as is the case with the surface structure  13   b  additionally designated as  17 . 
         [0045]    The depressions  25  can be in the form of craters or funnels. In one variant not shown in the figures, the depressions  25  can also be in a regular arrangement. 
         [0046]    The elevations  14  of the surface structure  17  differ from the elevations  14  of the surface structure  18  in that the former are in the form of craters or funnels with individual geometry and the latter are round, each with an identical geometry. A combination of the aforementioned examples is also conceivable, such as a combination of gridlike elevations  14  each with round or crater-like elevations  14  (not shown). Instead of a round geometry, as shown for the elevations  14  of the surface structure  18 , an elongate configuration is possible, as is represented for the elevations  14  of the surface structure  15 . 
         [0047]    All of the above described examples for elevations  14  apply not only to elevations  14  which protrude from the surface  16  into the fluid duct  3 , but also for depressions  25  provided in the surface  16 , and vice versa. A combination of depressions  25  and elevations  14  is also conceivable. 
         [0048]    Preferably, the individual elevations  14  have a height of at most 1 mm, preferably at most 0.2 mm, especially preferably a height of essentially 0.05 mm. In corresponding fashion, the depressions  25  have a depth of at most 1 mm, preferably at most 0.2 mm, especially preferably a depth of substantially 0.05 mm. The height or depth here is measured along a direction perpendicular to the surface  16 . 
         [0049]    The above explanations for possible configurations of the surface structure  13   b  on the valve seat  5  also apply, mutatis mutandis, for the surface structures  13   a ,  13   c  on the closure body  6  and on the adjustment element  9 . 
         [0050]    The surface structure  13   c  provided on the surface of the adjustment element  9  or the control tappet  10  is arranged in an axial end section  19  of the adjustment element  9  or the control tappet  10  facing the closure body  6 , on its circumferential side  20 . 
         [0051]    In the exemplary scenario, the surface structure  13   a  of the closure body  6  is arranged at least partially in a surface region of the closure body  6  which touches the valve seat  5  in the closed position of the closure body  6 . In analogous manner, the surface structure  13   b  of the valve seat  5  is arranged at least partially in a surface region which touches the closure body  6  in the closed position of the closure body  6 . Alternatively, no surface structures  13   a ,  13   b  can be formed on the closure body  6  and/or on the valve seat  5  in those surface sections touching each other in the closure body  6 , so as to rule out any lessening of the sealing action of the closure body  6  connected with this. 
         [0052]    The valve seat  5  comprises a first seat section  21   a  in the longitudinal cross section shown in the figures along the movement direction V of the adjustment element  9 , which passes into a second seat section  21   b  in the movement direction V. The first seat section  21   a  can have a constant diameter along the movement direction V. The second seat section  21   b  tapers conically away from the first seat section  21   a . In its closed position, the closure body  6  or the closure ball bears against the valve seat  5 . The second seat section  21   b  passes along the movement direction V away from the first seat section  21   a  into a third seat section  21   c , which can have a constant diameter along the movement direction V. The surface structure  13   b  of the valve seat  5  forming the noise reduction device  12  can be formed on an internal circumferential side  22  enclosing the fluid duct  3  on at least one of the three seat sections  21   a ,  21   b ,  21   c . In the example of  FIG. 4 , the surface structure  13   b  is shown as an example in the second and third seat sections  21   b ,  21   c . The surface structure  13   b  formed on the third seat section  21   c  of the valve seat  5  at the internal circumferential side  22  of the fluid duct  3  lies opposite the surface structure  13   c  formed on a circumferential side  20  of the adjustment element  9 . The surface structure  13   a  formed on the closure body  6  can be formed as a ring or a ring segment and extend on the surface of the closure body  6  along a direction X perpendicular to the movement direction V, preferably entirely around the circumference. 
         [0053]    The surface structures  13   a ,  13   b ,  13   c  with the elevations  14  and/or depressions  25  can be realized in the manner of a roughened surface, having a roughness Rz of more than 16 μm.