Abstract:
A final control element movable between a minimal and a maximal position for controlling an internal combustion engine is acted upon by a first spring element acting in the closing direction and a second spring element acting in the opening direction, the latter having a first end and a second end. The first end of the second spring element is supported in stationary fashion in a housing. The second spring element transmits its intrinsic tension in the tangential and radial directions either to a bearing point on the final control element or to a second bearing point of the housing and is adjustable in its angular position by means of an adjustable stop.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     In the automotive field, final control elements for controlling internal combustion engines are used that keep a control element between a minimal and a maximal position. A typical embodiment uses two spring elements, of which one works in the opening direction and one in the closing direction, and of which, one spring element at a time is not operative in a partial range. The spring acting in the closing direction is typically embodied as a helical or spiral spring, while the spring acting in the opening direction is embodied as a helical spring and as a leaf spring.  
         [0003]     2. Description of the Prior Art  
         [0004]     Final control elements for controlling internal combustion engines that have a currentless position between a minimal and a maximal position are known for instance from German Patent Disclosures DE 36 31 283 and DE 39 08 596. The final control elements known from these references each include two spring elements, one of which acts in the opening direction and one in the closing direction.  
         [0005]     From German Patent Disclosure DE 38 32 400 A1, an apparatus with a control motor for engagement with a transmission element is known. In this reference, an apparatus includes a control motor for engagement with a transmission element. The transmission element is operative between a human control element and a control device that determines the power of a driving machine. The human control element is connected to a rotary member, and the control device is connected to a second rotary member mechanism. A tension spring is also provided, which acts on the one hand on the first rotary element and on the other on the second rotary element, in such a way that the rotary elements seek to execute a rotary motion relative to one another, until a stop of one rotary element meets a stop of the other rotary element. A third rotary element is disclosed, with which the control motor is operatively connected and by which the second rotary element is rotatable. Between the first and third rotary elements there is a coupling, which is inoperative in a certain position of these rotary elements relative to one another. The third rotary element can be restored to a restoring element by means of at least one reverse rotation spring assembly acting directly or indirectly on the third rotary element. The reverse rotation spring assembly can either be operative in only one direction of rotation or, depending on the position of the third rotary element, in either one or the other direction of rotation. The reverse rotation spring assembly comprises at least one reverse rotation spring with two spring ends, of which the first spring end housing is fixedly supported, and the second spring end can act on the third rotary element in a reverse rotation direction via an attachment on the third rotary element.  
       OBJECT AND SUMMARY OF THE INVENTION  
       [0006]     By means of the provisions proposed according to the present invention, an easily installed restoring element for final control elements for controlling internal combustion engines is furnished which can be used for instance in a throttle device in the intake tract of an internal combustion engine or inside an exhaust gas recirculation valve in the exhaust tract of an internal combustion engine. The provisions proposed according to the invention are distinguished in that the restoring element of the final control element is embodied as an easily installed spring element which is retained in its position merely by housing stops under its own intrinsic initial tension. This makes for installation that is both economical and simple. The spring element proposed according to the invention, which can be embodied as a leaf spring, not only transmits torque but also brings a radially outward-acting force to bear. By means of this radial force, it is possible for the restoring element, upon installation, to slide on its own into its fastening variant and to maintain this position even during operation. The movable end of the restoring element is pressed either into a driver or into a bearing point, depending on the spring range, by this outward-acting radial force. Inside the bearing point, which may be embodied in a housing of a throttle device, the end received there of the restoring element has play. Because the bearing point has play, greater tolerances are acceptable for the individual parts; moreover, the design of the bearing point as a bearing point with play makes for easier installation.  
         [0007]     The unambiguous, defined contact of the restoring element is first achieved by the action of the spring forces. Compared to the version known from DE 38 32 400 A1, in the version proposed here, one additional receptacle and one fastening element on one end of the final control element can be dispensed with.  
         [0008]     Because of the simple installation, which is represented for instance by the bearing point, designed with play, inside a housing of a throttle device, a minimization of the number of components is attained compared to the version known from the prior art as defined by DE 38 32 400 A1. Advantageously, the restoring element is embodied as a C-shaped leaf spring which is prestressed by means of housing stops. The primary shape of the restoring element that can be embodied in a C shape advantageously covers an angular range between 180° and 360°. The term “primary shape” of the restoring element that can be embodied in the shape of a C is understood to mean the shape of the leaf spring without its spring ends that are bent at an angle, or in other words it essentially means the curved region of the leaf spring extending between the spring elements that are bent at an angle.  
         [0009]     In a further variant of the embodiment proposed according to the invention, which cooperates with a throttle valve that meets a stop and additionally with an external, lower mechanical stop, the currentless position of the emergency air position can be made adjustable to compensate for tolerances in the angular position. To achieve this compensation of tolerances, an adjusting screw may be provided at the appropriate bearing point of the leaf spring in the emergency air position and acts on the movable arm of the leaf spring. Depending on the depth to which the adjusting screw, which may for instance be in the form of a grub screw, is screwed in, the angular position of the movable arm of the leaf spring is varied. Varying the angular position of the movable arm of the leaf spring can take into account the fact that if there is a fixed connection between a toothed segment and the corresponding throttle valve shaft, it is not possible to compensate for tolerances by way of their fixed connection with one another, but the angular position of the leaf spring can be made adjustable. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]     The invention will be better understood and further objects and advantages thereof will become more apparent from the ensuing detailed description of preferred embodiments, taken in conjunction with the drawings, in which:  
         [0011]      FIG. 1  shows the restoring element proposed according to the invention in a first variant fastening;  
         [0012]      FIG. 2  shows the restoring element proposed according to the invention, embodied as a C-shaped leaf spring, in a second variant fastening;  
         [0013]      FIG. 3  shows the drive side of a throttle device, which is received in the intake tract of an internal combustion engine, with a restoring element proposed according to the invention and associated with the inside of the final control element;  
         [0014]      FIG. 4  shows a leaf spring, let into the housing on the drive side of a throttle device, whose movable arm can be prestressed via a stop that is provided with an adjusting screw;  
         [0015]      FIG. 5  shows the leaf spring, whose fixed arm is fastened in place and whose movable arm can be acted upon by a stop with an adjusting screw; and  
         [0016]      FIG. 6  shows the stop, acting on the movable arm of the leaf spring, with the adjusting screw. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0017]      FIG. 1  shows spring element  1 , which is essentially C-shaped by design, having a first end  3  and a second end  4 . The first end  3  of the spring element  1  is received, at a first bearing point  5 , in a housing not shown in  FIG. 1 . The first bearing point  5  includes a first support  6  and a second support  7 . The supports  6  and  7  are received at a spacing a offset from one another relative to the first end  3  of the spring element  1 . Moreover, the first bearing point  5  for the first end  3  of the spring element  1  has a third support  8 , which is offset by an angle of approximately 90° from the first support  6  of the first bearing point  5 . The supports  6 ,  7 ,  8  of the first bearing point  5  of the spring element  1 , in the illustration in  FIG. 1 , stand for stop faces on which the first end of the spring element  1  rests in a housing and is received there with play.  
         [0018]     The spring element  1 , preferably embodied as a leaf spring, has a curvature  9 . The curvature  9  is embodied such that a primary shape  10  is created with which the curved region of the spring element  1  extends over an angle of between 180° and 360°.  
         [0019]     The spring element  1  embodied as a leaf spring has a first bend  11 , which amounts to approximately 90° and may also be embodied at other angles, where the first spring end  3  changes over to the C shape  2  of the spring element  1 . The spring element  1  furthermore has a second bend  12 , which is embodied in the region of the second end  4  of the spring element  1 . The second bend  12  may be embodied in an angular range of between 30° and 90°, preferably 45° or 60°. In the illustration in  FIG. 1 , the spring element  1  is shown with its second, movable end  4 , because of its intrinsic tension acting in the tangential and radial directions, against a second bearing point  21  of a housing not shown in  FIG. 1 . The second bearing point  21  of the spring element  1  has a first support  22  and a second support  23 . The forces F T  (tangential force) and F R  (radial force) that are transmitted because of the intrinsic tension of the spring element  1  are transmitted to the first support  22  and the second support  23 , respectively, of a housing.  
         [0020]     The spring element  1  is associated with a final control element  13 , shown only schematically in  FIG. 1 , in accordance with a first fastening variant  20 . The final control element  13  is movable about a bearing point  16  and can be moved to arbitrary intermediate positions between a resting position  17  and a deflected position  18  shown in dashed lines in  FIG. 1 . The final control element  13  has a head region  14 , on which a contact face  15  is embodied. The contact face  15  of the final control element  13  is embodied in accordance with the curvature of the second bend  12  in the region of the second, movable end  4  of the spring element  1  and upon contact with it forms a bearing point  24  for the spring element  1  that is embodied with a C shape  2 .  
         [0021]     In the resting position  17  of the final control element  13 , the spring element  1 , because of its intrinsic tension, is moved into the first bearing point  5  and the second bearing point  21  of a housing not shown in  FIG. 1  and rests on the supports  6 ,  7  and  8  of the first bearing point  5  and on the supports  22 ,  23  of the second bearing point  21  in the housing. As long as the final control element  13  does not enter into engagement with the spring element  1 , preferably embodied as a leaf spring, the second, movable end  4  of the spring element  1  remains in its position shown in  FIG. 1 . If the final control element  13  is moved by a drive mechanism into its deflected position  18 , the head region  14  of the final control element  13 , with its contact face  15 , moves toward the second bend  12  in the region of the second, movable end  4  of the spring element  1  and contacts this bend and deflects the second, movable end  4  of the spring element  1  into the position shown in dashed lines in  FIG. 1 . In this state of the second, movable end  4  of the spring element  1 , the intrinsic tension of the spring element  1  is transmitted to the final control element  13  in both the tangential and the radial directions, as represented by the arrows F T , F R  in  FIG. 1 , in the deflected position  18  of the final control element  13 .  
         [0022]     As long as the variant embodiment, shown in  FIG. 1 , of the spring element  1  preferably embodied as a leaf spring is not contacted by the final control element  13 , the spring element  1  remains in its position inside the housing by its intrinsic initial tension. To facilitate the installation of the spring element  1  designed according to the invention in a housing, the first bearing point  5  is embodied with play, so that simple insertion of the first end  3  of the spring can be done into the contact faces of the housing that are represented by the supports  6 ,  7  and  8 .  
         [0023]     From the illustration in  FIG. 2 , a further fastening variant can be seen of the spring element proposed according to the invention and acting on a final control element. In this embodiment, spring element  1  which acts on the schematically shown final control element  13  includes a straight portion  31  that changes over to the primary shape  10 . The straight portion  31  of the spring element  1 , which in this variant embodiment is again preferably embodied as a leaf spring, is located between the curved region  9  of the spring element  1  and the first bend  11  of the spring element  1 . The first bend  11  in the region of the first end  3  of the spring is embodied as a 90° bend. Bending angles within a range of 90°±60° are possible. In the second fastening variant  30 , shown in  FIG. 2 , of the spring element  1 , the first bearing point  5  is embodied such that the first support  6  and the second support  7  are located opposite one another. From a production standpoint, this kind of support can be represented by a slot in a housing, into which the first end  3  of the spring element  1  is inserted. Furthermore, the first bearing point  5  for the first end  3  of the spring element  1  has the third support  8 , which is rotated 90° relative to the first support  6  of the first bearing point  5 . Opposite the third support  8 , there is a further support  32  at a spacing a. The straight portion  31  is embodied with a length  33 . In this variant embodiment of the first bearing point  5  for the first spring end  3 , the fastening position of the first spring end  3  of the spring element  1  is predetermined by the design of the first bearing point  5  in the housing. The primary shape  10  is located, analogously to a variant embodiment of the spring element  1  shown in  FIG. 1 , in an angular range between 180° and 360°. It can be seen from the second fastening variant  30  shown in  FIG. 2  that in the resting position  19  of the spring element  1 , this spring element is pressed by its intrinsic tension in the radial and tangential directions against the supports  22  and  23  of the second bearing point  21  in a housing not shown in  FIG. 2 . As soon as the final control element  13  is moved from its resting position  19  into its deflected position  18  or into an intermediate position, the second, movable spring end  4  is deflected into its position shown in dashed lines in  FIG. 2 . The contact face  15 , embodied in curved form, on the final control element  13  forms the bearing point  24 , at which the forces F R  and F T  acting in the radial and tangential directions because of the intrinsic tension of the spring element  1  are transmitted. In the deflected position  18 , shown in dashed lines in  FIG. 2 , of the final control element  13  and of the second, movable spring end  4 , the second, movable spring end  4  of the spring element  1  is raised from the second bearing point  21 , or in other words from the supports  22  and  23 .  
         [0024]      FIG. 3  shows the use of the spring element, proposed according to the invention and acting on the final control element, in a throttle device  40  whose housing side toward the drive mechanism is shown. On the drive side of a housing  41 , there is a pinionlike drive wheel  44 , which is driven via a drive mechanism  43 . The drive wheel  44  meshes with a first transmission element  45 , which is received on a shaft  47  on which shaft a second, likewise pinionlike transmission element  46  is received in a manner fixed against relative rotation. The second transmission element  46  of the common shaft  47  meshes with a toothed segment  42  which is embodied on the final control element  13 . The leaf spring-like spring element  1  embodied with the C shape  2  is located behind the final control element  13 . The first end  3  of the spring element  1  is received in the slotlike first bearing point  5  in the housing  41  of the throttle device  40 , while the second, movable end  4  of the spring element  1  is received in the second bearing point  21  of the housing  41 . In the view in  FIG. 3 , the spring element  1  is fastened into the housing  41  of the throttle device  40  in the first fastening variant  20 , which is described in further detail in conjunction with  FIG. 1 . It can be seen from  FIG. 3  that the spring element  1 , embodied as a leaf spring, has the curvature  9  which extends over an angular range of between 180° and 360°. The second, movable end  4  of the spring element  1 , as shown in  FIG. 3 , rests on the first support  22  and the second support  23  of the second bearing point  21  of the housing  41 . In the region of the second bend  12 , which is embodied at an angle of between 30° and 90° but preferably 45° or 60°, the final control element  13  rests, with its contact face  15  embodied on its head region  14 , on the spring element  1  that is preferably embodied as a leaf spring. In the position shown in  FIG. 3 , the final control element  13  is still barely not touching the second, movable end  4  of the leaflike spring element  1 . As a result, the second, movable end  4 , because of its intrinsic tension acting in the tangential and radial directions, rests on the supports  22 ,  23  of the second bearing point  21  of the housing  41 . The final control element  13  is rotatable about the final control element bearing  16 . Extending concentrically to the bearing  16  of the final control element  13  that has the toothed segment  42  is a throttle valve shaft, which is not shown in  FIG. 3  because it is concealed and on which a throttle valve is received. The gas stream passing through a gas flow opening  48  in the throttle device  40  is controlled by the throttle valve. The wall which penetrates the gas flow opening  48  of the housing  41 , preferably embodied as an injection-molded component, of the throttle device  40  is identified by reference numeral  49 . The region of the housing  41  where the drive shaft of the drive mechanism  43  penetrates the housing  41  is provided with a reinforcing ribbing  50 . The supports  22  and  23 , shown schematically in  FIG. 1 , of the second bearing point  21  for spring element  1  in the housing  41  are embodied, in the view of  FIG. 3 , as contact faces, on which the second, movable end of the spring element  1 , preferably embodied in leaflike form, rests. Because of its intrinsic tension, the spring element  1 , as long as it is not deflected by the final control element  13  that can be pivoted about the bearing point  16 , remains in its fastening variant inside the housing  41 , or in other words is pressed against the contact faces of the first bearing point  5  and the second bearing point  21  inside the housing  41  of the throttle device  40 . As soon as the second, movable end  4  of the spring element  1  is deflected by a rotary motion of the final control element  13  about its axis  16 , the intrinsic tension of the leaflike spring element  1 , which acts in both the tangential and the radial directions, is transmitted to the deflected final control element  13 .  
         [0025]     If the first bearing point  5 , in which the supports  6 ,  7 ,  8 , which are preferably embodied as contact faces for the first end  3  of the spring element  1 , is manufactured in slot form, then advantageously simply placing the leaflike spring element  1  in the housing  41  suffices. After the leaflike spring element  1  has been placed and fastened in the housing  41  of the throttle device  40 , its ends  3  and  4  are thrust into the first bearing point  5  and the second bearing point  21 , respectively, so that the spring element  1  is prestressed in the respective bearing points  5  and  21 .  
         [0026]     In a further variant embodiment of the version proposed according to the invention, the housing  41  of the throttle device  40  includes an external, lower mechanical stop  51  ( FIG. 4 ) as well as a further, adjustably embodied stop, which serves to adjust the emergency air position. The spring element  1  embodied like a leaf spring in the curvature  9 , is fixedly fastened by its first end  3  at the first bearing point  5  of the housing  41 . The second, movably embodied end  4  of the leaf-spring-like spring element  1  is located opposite a guide rib  53 , which is embodied in the housing  41  of plastic. The second end  4  of the spring element  1  embodied like a leaf spring is located facing a second adjusting screw  54  for adjusting the emergency air position. Via the second adjusting screw  54 , the prestressing of the movable arm of the spring element  1  can be varied. From  FIG. 4 , it can furthermore be seen that above the leaflike spring element  1  embodied in the curvature  9  there is a toothed segment  42 . The toothed segment  42 , with its toothing, meshes with the second transmission element  46 , which is received on the common fixed shaft  47  on which the first transmission element  45  is also located. The drive mechanism associated with the common fixed shaft  47  is not shown in  FIG. 4  (but see  FIG. 3 ), for the sake of greater clarity.  
         [0027]     Reference numeral  57  designates a driver which is embodied on the toothed segment  42  and cooperates with the spring element  1  in the form of a leaf spring.  
         [0028]     The degree of rotation of the toothed segment  42  may be varied via an adjusting screw  52  disposed in the external, lower mechanical stop  51 , while the angular position of the movable arm of the spring element  1  embodied like a leaf spring, is possible via a rotation of the adjusting screw  54 . In this variant embodiment, it is accordingly possible, for compensating for tolerances, to adjust the angular position of the spring element  1 , embodied like a leaf spring, cooperating with the toothed segment  42  by way of an actuation of the second adjusting screw  54  with respect to its emergency air position. The toothed segment  42  includes a cam, which is located opposite an adjusting screw that is received in the external, lower mechanical stop  51 . The stop position of the cam and thus the course of rotation of the toothed segment  42  are limited by means of a rotation of the adjusting screw  52  in the external, lower mechanical stop  51 .  
         [0029]     In the view shown in  FIG. 5 , the toothed segment  42  (not shown) is prestressed via a helical/torsion spring  59  whose end is embodied as a hook  60 . By means of the hook  60 , which is suspended from the toothed segment  42 , the spring force is transmitted to the toothed segment  42  in order to effect its restoration. It can be seen from the view in  FIG. 5  that a fixed arm  55  of the leaflike spring element  1  is fastened firmly in place on the first end  3  in the first bearing point  5 . A movable arm  56  of the leaflike spring element  1 , on which the bearing point  24  for the drivers of the toothed segment  42  is embodied, comes to an end at the second end  4 . The second end  4  of the movable arm  56  has the guide rib  53  fitting over it in the housing  41 . The adjusting screw  54  for determining the emergency air position is let into the stop base  62 . Rotating the adjusting screw  54  can move the second end  4 , embodied in the form of a right-angle bend, of the leaflike spring element  1 . As also seen from  FIG. 5 , the external, lower mechanical stop  51  is located in the housing  41 . It receives the adjusting screw  52  for determining the maximum rotated position of the toothed segment  42 , not shown in  FIG. 5  and acted upon by the helical/torsion spring  59 . Reference numeral  47  indicates the common shaft, likewise injection-molded into the housing  41 , on which shaft both the first transmission element  45  and the second transmission element  46 , which meshes with the toothed segment  42 , are received.  
         [0030]     In  FIG. 6 , the stop base  62 , which supports the adjusting screw  54  for determining the emergency air position, can be seen on a larger scale. Once again, it is injection-molded into the housing  41 , the latter preferably embodied as an injection-molded plastic component. The right-angle bend  61  of the free end  4  of the movable arm  56  is located below the grip  53 .  
         [0031]     The spring element  1  embodied as a leaf spring, in the prestressed installation position, is braced firmly on the housing  41  by its fixed arm  55  on the first bearing point  5 . The movable arm  56  is movable, with its end embodied with a right-angle bend  61 , along the guide rib  53  and rests tangentially on the adjusting screw  54  for determining the emergency air position. The driver, embodied on the toothed segment  42  and meshing with the bearing point  24  of the movable arm  56 , travels over a shorter radius, compared to the bent part of the movable arm  56  of the spring element  1  in the form of a leaf spring. It is assured as a result that the driver  57 , coming from the direction of maximal opening, lifts the movable arm  56  inward radially away from the guide rib  53 . In the further motion out of the emergency air position in the direction of a minimal opening of the throttle valve, the movable arm  56  accordingly does not rub along the guide rib  53 . The guide rib  53  is embodied as an arc that is concentric with the throttle valve shaft. Because of this, the movable arm  56  of the spring element  1  may have an adjusting range of ±1.5 mm, in every position of the adjusting screw  54  for determining the emergency air position. Moreover, this always assures the same radial spacing from the center of rotation. As a result, the radial spacings of the driver  57  of the toothed segment  42 , which rests on the movable arm  56 , relative to the movable arm  56  within the adjustment range are always the same.  
         [0032]     The foregoing relates to preferred exemplary embodiments of the invention, it being understood that other variants and embodiments thereof are possible within the spirit and scope of the invention, the latter being defined by the appended claims.