Abstract:
The invention relates to a supply device for the supply of pressure fluid into at least one vehicle brake or into a pressure fluid accumulator, wherein a piston is movably arranged in an accommodating member, a carrier bears a non-return valve arranged coaxially to the piston for the purpose of ventilating a working chamber into which the piston plunges, and wherein a resetting spring is arranged between the carrier and the piston. It is the essence of the invention that a multi-piece cage allows inserting the resetting spring into the cage parts, the cage parts comprise fastening means that lock the cage due to relative displacement of the cage parts, and the resetting spring is caged and simultaneously elastically preloaded under the relative displacement of the cage parts.

Description:
TECHNICAL FIELD  
       [0001]     The present invention relates to a supply device for the supply of pressure fluid into at least one vehicle brake, or into a pressure fluid accumulator, or into a master brake cylinder, wherein a piston is movably arranged in an accommodating member, a carrier bears a non-return valve arranged coaxially to the piston for the purpose of ventilating a working chamber into which the piston plunges, and wherein a resetting spring is arranged between the carrier and the piston.  
       BACKGROUND OF THE INVENTION  
       [0002]     EP 0 734 494 A1 discloses a supply device configured in this type. The piston is a component of a unit which may be handled independently. The unit additionally comprises a second non-return valve for the ventilation of the working chamber, and the resetting spring. This arrangement allows inserting the mentioned components as a unit into a bore in the accommodating member. In a separate step the carrier for the non-return valve is inserted into the extended bore, while the resetting spring is elastically preloaded at the same time. The process reliability of this mounting operation needs improvement because the resetting spring may buckle under increasing preload. To prevent this, special adaptation measures are provided. Those measures shall be avoided.  
       BRIEF SUMMARY OF THE INVENTION  
       [0003]     An object of the invention is to provide a supply device having a design that permits a simplified assembly by forming modular units and a preload of the resetting spring.  
         [0004]     This object is achieved by a multi-piece cage which allows inserting the resetting spring into the cage parts, the cage parts comprising fastening means that lock the cage due to relative displacement of the cage parts, and the resetting spring is caged and simultaneously elastically preloaded under the relative displacement of the cage parts.  
         [0005]     The invention allows simultaneous preloading of the resetting spring while joining the cage parts together, and vice-versa. The assembly process is worked outside the accommodating member of the component which accommodates the spring assembly after installation. The invention allows the pre-assembly of a return spring subunit. That is achieved by a division of working steps.  
         [0006]     In a particularly preferred embodiment, a catch-type connection is provided for fastening the cage parts to one another, and a locking arm is provided on at least one cage part for engagement into a locking recess of an associated second cage part. This arrangement avoids cost-intensive separate fastening steps such as a welding operation or a beading operation.  
         [0007]     Several fastening means, preferably arranged in pairs and diametrically opposite each other are provided at each cage part in a further favorable embodiment of the invention. Safe accommodation of the spring forces in the cage is thereby rendered possible with little effort. It is principally feasible to raise the number of fastening means.  
         [0008]     The opposed fastening means of a cage component preferably have an equal design what facilitates the fabrication by tools when the cage parts are made from sheet-metal material. In addition, the feeding of parts in an automatic assembly process can be simplified. It is, however, also possible to provide in each case different fastening means without departing from the spirit of the invention.  
         [0009]     Joining of the cage parts is facilitated when each cage part includes at least one separate portion for centering a portion of a cage part to be fastened. Besides, if desired, there is no need for separate sorting processes or position-aligning operations during the assembly. According to a preferable variant of the invention, the fastening means are arranged in such a fashion, without possibly needing a separate portion for centering purposes, that a rotational alignment of the cage components with respect to the component axis can be omitted. This is brought about because the cage parts include more locking arms than locking recesses, and the locking arms in the circumferential direction of the cage parts have a considerably smaller width than a width of the locking recesses so that cage parts that are arranged in an optionally twisted relative position to each other in a circumferential direction of the cage parts are directly lockable. Details of this embodiment can be taken from the sub claims.  
         [0010]     The influence of component tolerances is minimized because a cage part has a cylindrical wall with which the cage is accommodated in a carrier for forming a modular unit, and the carrier-side accommodating area is provided independently of and spaced from the fastening means for the cage parts. Therefore, e.g. a dimensional discrepancy in the accommodating area does not have any direct effect on the attachment of the cage parts to each other, and vice-versa.  
         [0011]     A subordinate patent claim discloses a spring assembly comprising two cage parts and a resetting spring for use in an electronically controlled brake system. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0012]      FIG. 1  is a cross-sectional view of a supply device.  
         [0013]      FIG. 2  is a cross-sectional view of a first cage part with locking arms.  
         [0014]      FIG. 3  is a cross-sectional view of a second cage part with a locking recess.  
         [0015]      FIG. 4  is a perspective view of a second embodiment of a cage in the mounted condition.  
         [0016]      FIG. 5  is an explosive view of the components of the cage according to  FIG. 4 .  
         [0017]      FIG. 6  is a perspective sketch for illustrating the overlapping of fastening means on cage parts. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0018]      FIG. 1  shows a supply device  1  having a piston  2  that is arranged and guided so as to be movable in a bore  3  of an accommodating member  4 , which latter is a component of an electrohydraulic assembly equipped with an electronic control unit (ECU). To guide the piston  2 , it is also possible to use a bushing inserted into the bore  3  or, as will be described in the following, a combined solution in which the bushing, cage  16  and non-return valve  7  form an assembly. Further, the accommodating member  4  includes non-illustrated, electromagnetically actuatable valves and channels (not shown) connecting the valves and allowing the supply of pressure fluid out of a working chamber  11  into a non-illustrated pressure-fluid accumulator or into non-illustrated vehicle brakes for the purpose of a controlled pressure increase. This arrangement enables a controlled braking of the vehicle or a control intervention such as a driving stability control intervention (ESP) or any other control intervention such as slip control in particular.  
         [0019]     The piston  2  with one end abuts indirectly by way of a roller bearing on a driving eccentric, which is set rotating by means of a shaft of an electric motor not shown. A resetting spring  5  is inserted between a carrier  6  for a non-return valve  7  (pressure valve) and the piston  2 .  
         [0020]     As can be taken from  FIG. 1 , a non-return valve  7  configured as a pressure valve is used for the ventilation of the working chamber  11 . For this purpose, a valve member  8  is pressed by a spring  9  permanently into a closing position for abutment on a carrier-side sealing seat  10 . Only in a pressure stroke of the piston  2  will the pressure difference applied to the valve member  8  overcome the active spring forces so that the valve member  8  moves into the non-illustrated opening position for the ventilation of the working chamber  11 , with the result that the outlet of pressure fluid out of the working chamber  11  takes place. The pressure fluid outlet A is closed in the aspiration stroke, and the pressure fluid propagates into the working chamber  11  through a non-return valve  12  provided in an inlet E and being shown in the closing position.  
         [0021]     The carrier  6  has a bipartite design and includes a disc-shaped bottom  13  on which the sealing seat  10  for the non-return valve  7  is provided. A bottom  13  contains a through-bore to the pressure fluid passage from the working chamber  11  into the outlet A. A bowl-shaped second part  14  is attached to the bottom  13  and receives a bowl  15  for the spring  9 . On a side opposite the second part  14 , there is a cage  16  for the packet-type preloaded resetting spring  5 , said cage including two cage parts  16 ,  17  and, in addition, a bowl-shaped spring retainer  19  for abutment and centering of the resetting spring  5  on the piston  2 . In the completely assembled condition, the spring retainer  19  abuts on a frontal piston end and overlaps with a bowl wall  30  the piston  2  at least in part in the area of the piston end  31 . An operative clamping engagement between spring retainer  19  and piston  2  is possible.  
         [0022]     As can be seen, also the cage parts  17 ,  18  are designed as bowl-type sheet-metal shaped parts with a cylindrical wall and with a brim  29  or a bottom  27 , on which in each case one end of the resetting spring  5  is movable into abutment.  
         [0023]     In the mounted condition of the supply device, the brim  29  with an outside surface retains a piston seal  33  in its position within the stepped bore  3 . Upon delivery of the cage subassembly, however, the spring retainer  19  bears against an inside surface of brim  29 . In a combined solution, the cage parts  16 ,  17  can principally have a guiding and bushing function for the piston  2  and, further, an integrated retaining function for one or both of the non-return valves  7 ,  12 .  
         [0024]     Depending on the desired adaptation of the supply device, the cage parts  17 ,  18  can have corresponding apertures  28 . When a low-cost protection again foreign objects is desired, the apertures  28  can be designed like a sieve in order to protect the pressure valve against contamination and produce a filtering effect. To improve the low-temperature behavior in the case of a viscous pressure fluid, the cage parts  16 ,  17  can include extended apertures  28  in the cylindrical wall and in the bottom  27  that can be covered by filter screens. However, if a sufficient number of unused locking recesses  25 ,  26  are provided, their opening cross-section may already be adequate to allow a good aspiration behavior so that attention to a good discharge performance out of the working chamber  11  must only be paid in the area of the bottom  27 . For this purpose, the bottom  27  can be provided with generous apertures  28  and, in case of need, with additional filter screens. The cage  16  can be equipped with apertures  28  until its stability limit because the cage effect is only needed until the final assembly of the supply device. The cage effect is no more required in the operation of the supply device. For this reason, as little material as possible is used for the cage parts  17 ,  18 . Only a combined solution departs from this principle.  
         [0025]     In an essential feature of the invention, the cage parts  17 ,  18  are so configured that they accommodate the resetting spring  5  and, additionally, serve both as a tool and as cage  16  for preloading purposes. The cage parts  17 ,  18  provided with fastening means  20  are locked by means of displacement of these cage parts  17 ,  18  relative to each other, while preloading the resetting spring  5  simultaneously. Separate process steps for fastening the cage parts  17 ,  18  to each other are omitted.  
         [0026]     A locking engagement is provided for the mutual attachment of the cage parts  17 ,  18 , and two equal as well as diametrically opposite protruding locking arms  21 ,  22  are provided at the cage part  17 , the free arm ends  23 ,  24  engaging in a form lock into each one locking recess  25 ,  26  at the other cage part  17 ,  18 . It is, however, also possible to arrange each one locking arm and each one locking recess at each cage part  17 ,  18  so that the fastening means  20  are provided in pairs, yet unlike each other. It is furthermore feasible to refrain from the pairwise arrangement of the fastening means  20  by e.g. providing an odd number of fastening means  20 , e.g. three in each case.  
         [0027]     Preferably, each cage part  17 ,  18  has at the end of its cylindrical wall—that is preferably at a point which is the first to get into engagement with the opposite cage part  17 ,  18 —a distinctly rounded or conically tapered guiding portion  32  for the radial centering and guiding of the other cage part  18 ,  17  to be fastened. According to  FIG. 3 , the guiding portion  32  is situated at the cage part  18 , what is, however, also possible vice-versa or generally at both cage parts  17 ,  18 . More specifically, the associated cage parts  17 ,  18  can quasi align automatically relative to each other by means of guiding portion  32  during their process of approach. All guiding portions  32  are so designed that the space requirement in the accommodating member  4  is not unnecessarily increased. This necessitates a general orientation of the guiding portions  32  radially to the inside. Spaced axially from the guiding portion  32  and spaced from the fastening means  20  is an accommodating portion by which the cage  16  is accommodated in particular in an indentation of bottom  13  in operative or positive engagement for forming a modular unit. Both the guiding portion  32  and the accommodating portion are generally disposed on a common diameter of the tubular wall of the respective cage part  17 ,  18 .  
         [0028]     Primarily one embodiment has been described hereinabove which requires an accurately aligned feeding of the cage parts in a cage-part circumferential direction U during the assembly process in order that the fastening means  20  become active. Advantageously, this requirement can be circumvented by a variant according to FIGS.  4  to  6 . As can easily be seen in FIGS.  4  to  6 , the cage parts  17 ,  18  have a larger number of locking arms  21 ,  22  than locking recesses  25 ,  26 , and the locking arms  21 ,  22  have a width B in the cage-part circumferential direction U which is considerably smaller than the corresponding width b of the locking recesses  25 ,  26  (with respect to the cage-part circumferential direction U). Due to this provision, cage parts  17 ,  18  being twisted relative to one another as desired can be paired with each other for locking purposes, without the need for a separate indexing of components or a separate alignment. It is only necessary to pay attention that the correct sides of the cage parts  17 ,  18  with their fastening means  20  lie opposite each other, what can be polled or safeguarded in a simple manner. Combined with the guiding portions  32  for a radial centering of the cage parts  17 ,  18 , this variant allows an especially favorable, because process-reliable, assembly. The absolute number of locking arms and locking recesses as well as their absolute dimensioning in the cage-part circumferential direction U can be varied in many ways within the limits that the number of all locking arms  21 ,  22  must be larger than the number of all locking recesses. In the embodiment shown, six locking arms  21 ,  22  having the width B and four locking recesses  25 ,  26  having the width b are provided as an example only.  
         [0029]     Eventually,  FIG. 6  shows in a perspective view two cage parts  17 ,  18 , and the interposed sketch shows fields with a defined width and arrangement in the cage-part circumferential direction U, which correspond to the actual arrangement of a corresponding fastening means at a cage part. More specifically, the width B, b of the locking arms  21 ,  22  and locking recesses  25 ,  26  is plotted, and effective locking exists in this area only if the width B is congruent with the width b. All other fastening means  20 , which are not congruent or only in part, remain without effect. As is shown in  FIG. 6 , congruence prevails only in the area of the crosshatched fields so that only those fastening means  20  are effective which are basically diametrically opposite each other, whereby a defined locking of the cage  16  is ensured.  
         [0030]     It is to be understood that the invention is expressly not limited to the casing of piston resetting springs of supply devices for slip-controlled brake systems (ABS, TCS, ESP).  
         [0031]     Therefore, it shall be mentioned as an example only that an extension to spring assemblies of non-return valves with two or more cage parts and one resetting spring for elastically preloading a closure member in the direction of a sealing seat is possible without departing from the basic idea of the invention. For further simplification, the sealing seat can be integrated at a cage part.  
         [0000]     List of Reference Numerals:  
         [0000]    
       
           1  supply device  
           2  piston  
           3  bore  
           4  accommodating member  
           5  resetting spring  
           6  carrier  
           7  non-return valve  
           8  valve member  
           9  spring  
           10  sealing seat  
           11  working chamber  
           12  non-return valve  
           13  bottom  
           14  part  
           15  bowl  
           16  cage  
           17  cage part  
           18  cage part  
           19  spring retainer  
           20  fastening means  
           21  locking arm  
           22  locking arm  
           23  end  
           24  end  
           25  locking recess  
           26  locking recess  
           27  bottom  
           28  aperture  
           29  brim  
           30  bowl wall  
           31  piston end  
           32  guiding portion  
           33  piston seal  
          U cage-part circumferential direction  
          B width (locking arm)  
          B width (locking recess)