Patent Publication Number: US-2012024104-A1

Title: Parking brake drive unit

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application relates to and claims priority to Spanish Patent Application No. P201031191, filed Jul. 30, 2010. 
     TECHNICAL FIELD 
     The invention relates to parking brakes for vehicles. 
     BACKGROUND 
     The prior art contains known parking brake drive units that comprise a lever assembled in a pivoting manner on a support fixed to the chassis of the vehicle and disposed to be operated by causing its rotation in one or another direction to tighten a brake device. A catch member enables the rotation of the lever in a braking direction but prevents its rotation in an opposite direction, as a result of which the lever remains in the maximum tightening position reached. On the lever is disposed a button that may be operated manually to release the catch member and thereby loosen the tension of the brake device. Generally speaking, the catch member includes a catch lever assembled in a pivoting manner on the aforementioned main lever, and this catch lever has at least one claw adapted to engage in a geared sector fixed on the aforementioned support of the main lever. The button and the catch member are connected mechanically by means of a rod, and a spring is disposed to push the claw of the catch member against the geared sector. 
     European patent EP1650092 B1 discloses a parking brake drive unit of the type described above, in which the button is assembled on the main lever and connected to one end of a rod that has a second end adapted to push the catch member, which disengages the claw from the geared sector when the button is operated. The device includes a first spring or main spring similar to a conventional one to return the button to its extended position, and a second spring, or catch spring, disposed between a portion of the catch member and a portion of the rod to push one against the other and the claw against the geared sector of the support at the same time. 
     SUMMARY OF THE DISCLOSURE 
     According to one implementation a parking brake drive unit is provided comprises a main lever assembled in a pivoting manner on a support and disposed to be operated to activate a brake device; a catch member assembled in a mobile manner on the main lever and which has at least one engagement means, preferably a claw, adapted to engage in a preferably geared sector fixed on the support; a main spring disposed to push the claw of the catch member against the geared sector; and a button assembled on the main lever and connected to a movable rod, adapted to move the catch member in a suitable direction to disengage engagement means from the geared sector when the button is operated. The parking brake drive unit further comprises a locking device that immobilises the rod when the locking device is not activated electrically. 
     When the parking brake drive unit is activated, the main lever is rotated in relation to the fixed support and the brake device is tightened. In this situation if the locking device is activated electrically, the rod is not immobilised and the main lever may rotate, with it returning to its rest position, as when the button is pressed it acts on the rod, which is not immobilised, and this piece, which is adapted to move the catch member, releases it, disengaging the claw from the geared sector. The brake device may thus be loosened and the unit released. 
     If the locking device is not activated electrically, the rod is locked, with the result that when the button is pressed it cannot move and cannot act therefore on the catch member, and the unit is locked. 
     According to one implementation, a parking brake drive unit for a vehicle is provided comprising: a main lever having a proximal end and a distal end, the distal end assembled in a pivoting manner on a support; a brake device coupled with the distal end of the main lever and moveable with the main lever as the main lever pivots in relation to the support; a stationary geared sector fixed to the support and disposed at or near the distal end of the main lever; a catch member assembled in a mobile manner on the main lever and which has an engagement member adapted to engage with the geared sector, the engagement member urged toward the geared sector by a spring; a first rod having a length extending between a first end and a second end, the first rod operatively coupled with the catch member and moveable between a first axial rest position and a second axial position, when in the first axial rest position the engagement member engages with the geared sector and when in the second axial position the engagement member is not engaged with the geared sector, the first end of the first rod positioned at or near the proximal end of the main lever that when acted upon causes the first rod to be moved between the first axial rest position and the second axial position, the first rod having a receptacle disposed in a position along its length; and an electrically activated locking device attached to the main lever in a fixed position relative to the first rod, the locking device comprising a member that is moveable between a first position when the locking device is electrically de-activated and a second position when the locking device is electrically activated, when in the first position the member resides in the receptacle of the first rod to lock the first rod in the first axial rest position, when in the second position the member resides outside the receptacle of the first rod to permit movement of the first rod between the first axial rest position and the second axial position. 
     According to another implementation, a parking brake drive unit for a vehicle is provided comprising: a main lever having a proximal end and a distal end, the distal end assembled in a pivoting manner on a support; a brake device coupled with the distal end of the main lever and moveable with the main lever as the main lever pivots in relation to the support; a stationary geared sector fixed to the support and disposed at or near the distal end of the main lever; a catch member assembled in a mobile manner on the main lever and which has an engagement member adapted to engage with the geared sector, the engagement member urged toward the geared sector by a spring; a flexible rod operatively coupled with the catch member and moveable between a first axial rest position and a second axial position, when in the first axial rest position the engagement member engages with the geared sector and when in the second axial position the engagement member is not engaged with the geared sector, a first end of the flexible rod positioned at or near the proximal end of the main lever that when acted upon causes the flexible rod to be moved between the first axial rest position and the second axial position; a rigid member coupled with the flexible rod and slideable between first and second positions on the main lever, the rigid member having a receptacle in a side thereof; and an electrically activated locking device attached to the main lever in a fixed position relative to the rigid member, the locking device comprising a member that is moveable between a first position when the locking device is electrically de-activated and a second position when the locking device is electrically activated, when in the first position the member resides in the receptacle of the rigid member to lock the flexible rod in the first axial rest position, when in the second position the member resides outside the receptacle of the rigid member to permit movement of the flexible rod between the first axial rest position and the second axial position. 
     According to another implementation, a parking brake drive unit for a vehicle is provided comprising: a main lever having a proximal end and a distal end, the distal end assembled in a pivoting manner on a support; a brake device coupled with the distal end of the main lever and moveable with the main lever as the main lever pivots in relation to the support; a stationary geared sector fixed to the support and disposed at or near the distal end of the main lever; a catch member assembled in a mobile manner on the main lever and which has an engagement member adapted to engage with the geared sector, the engagement member urged toward the geared sector by a spring; a first flexible rod having a first end portion and a second end portion, the first end portion positioned at or near the proximal end of the main lever; a second flexible rod having a first end portion and a second end portion, the second end portion of the second flexible rod coupled to the catch member; a rigid member coupled with the second end portion of the first flexible rod and the first end portion of the second flexible rod and slideable between first and second positions on the main lever, the rigid member having a receptacle in a side thereof, when the rigid member is in the first position the engagement member engages with the geared sector and when the rigid member is in the second position the engagement member is not engaged with the geared sector; and an electrically activated locking device attached to the main lever in a fixed position relative to the rigid member, the locking device comprising a member that is moveable between a first position when the locking device is electrically de-activated and a second position when the locking device is electrically activated, when in the first position the member resides in the receptacle of the rigid member to lock the rigid member in the first position, when in the second position the member resides outside the receptacle of the rigid member to permit movement of the rigid member between the first and second positions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows a side view of an embodiment of a parking brake drive unit in a situation in which the brake is activated and locked. 
         FIG. 2  shows a side view of the unit of  FIG. 1  in a situation in which the brake is activated and unlocked. 
         FIG. 3  shows a side view of the unit of  FIG. 1  in a situation in which the brake is unlocked. 
         FIG. 4  shows a side view of another embodiment of the parking brake drive unit of the invention in a situation in which the brake is unlocked. 
     
    
    
     DETAILED DESCRIPTION 
       FIGS. 1 to 3  show a parking brake drive unit with locking device in accordance with an example embodiment.  FIG. 1  shows a side view of the parking brake drive unit in a situation in which the brake is activated and locked.  FIG. 2  shows the unit of  FIG. 1  in a situation in which the brake is activated and unlocked.  FIG. 3  shows the unit of  FIG. 1  in a situation in which the brake is unlocked. In one implementation the parking brake drive unit comprises a main lever  3  assembled so that it may pivot in relation to an axis  10  on a support  6  fixed to the chassis of the vehicle. The main lever  3  is disposed to be operated to activate a brake device  11 , such as, for example, a cable that is coupled to a brake. The tension of the device  11  increases as the free end of the main lever  3  is raised. 
     On the main lever  3  is assembled a catch member  5 , which, in the example shown, has the form of a lever assembled to pivot in relation to an axis  12 , but which may adopt other configurations, such as that of an appropriately guided sliding member. In this example, the aforementioned catch member  5  has a first arm on a first side of the axis  12 , on which there is an engagement member or means, such as a claw  13  in this case, while on a second arm on a second side of the axis  12  of the catch member  5 , is found a support member  15  that is connected with or otherwise engageable with a second end  16  of an auxiliary rod  2 . 
     In this example embodiment, on the free end of the main lever  3  there is a button  7  that may be assembled in a sliding manner and connected to a first end of a movable rod  1 , although they may be components made up of a single piece. In one implementation rod  1  has a receptacle  17  situated to receive a moveable shaft  9  of an electrically actuated locking device  4 . In one implementation rod  1  is connected in a sliding and coaxial manner at its second end to a first end of the auxiliary rod  2 . As explained above, the second end  16  of the auxiliary rod  2  is adapted to engage with the support member  15  of the catch member  5  and push it in a suitable direction to separate the aforementioned engagement member  13  from the geared sector  14  when the button  7  is depressed. To return the button  7  to an extended position in relation to the main lever  3 , after having been depressed, there is a spring (not shown in the figures) that acts on the auxiliary rod  2  and, through its sliding connection with the rod  1 , acts on the button  7  to urge it to its original rest position. In addition, as the spring acts on the auxiliary rod  2 , its second end  16  acts on the support member  15  of the catch member  5 , which pushes the engagement member  13  against the geared sector  14 . 
     On the main lever  3  is assembled a locking device  4  facing the rod  1 , which in the example shown comprises an electric actuation system  8  (e.g., an electromagnet) and a moveable shaft  9 . When the electric actuation system  8  receives an electrical signal, it is activated and the moving shaft  9  is withdrawn in a direction away from and out of the receptacle  17  of rod  1 , and when it does not receive an electrical signal it is deactivated and the moveable shaft  9  is extended and is housed in the receptacle  17  of rod  1 . 
     To activate the parking brake drive unit from the rest position, the handle of the main lever  3  is seized and moves upwards, it being rotated in relation to the fixed support  6  and the brake device  11  tightening. This operation may be performed whether an electrical signal reaches locking device  4  or not. If the signal arrives, the moveable shaft  9  is withdrawn, and when the signal does not arrive the moving shaft  9  is extended and housed in the receptacle  17  of rod  1 , although during the movement of the main lever  3  there is nothing to prevent the pivoting of the catch member  5  on its axis  12 , pulling the claw  13  on the geared sector  14 . 
     To deactivate the parking brake drive unit, the handle of the main lever  3  is seized and the button  7  pressed in order to release the catch member  5 . In this situation, if the locking device  4  is activated electrically, the moveable shaft  9  is withdrawn from the receptacle  17  of rod  1  and the main lever  3  may rotate, returning it to its rest position, as when the button  7  is pressed it acts on the rod  1 , which is not locked, and this in turn permits rod  1  to move axially to act on the auxiliary rod  2 , which is connected in a sliding manner to it. The auxiliary rod  2  thus acts on the catch member  5  and disengages the engagement member  13  from the geared sector  14 . The brake device may thus be loosened and the unit released. 
     If the locking device  4  is not activated electrically, the moveable shaft  9  is extended and housed transversally in the receptacle  17  of rod  1 . In this situation the rod  1  is locked, with the result that when the button  7  is pressed, the rod  1  cannot move axially and cannot therefore act on the auxiliary rod  2 , as a consequence of which it does not allow the catch member  5  to be acted on and the engagement member  13  remains engaged in the geared sector  14 . The unit is thus locked and its improper use is prevented. However, the main lever  3  may be rotated further upwards in relation to the rest position, and may therefore tighten the brake device  11  more, as the auxiliary rod  2 , as it is sliding and coaxial to the rod  1 , enables the catch element  5  to pivot in relation to its axis  12  and the engagement member  13  may be moved on the geared sector  14 . 
     In other alternative example embodiments, the locking device  4  comprises a piezoelectric sensor, an electric motor or similar member, which when activated electrically converts the electrical signal into a mechanical movement, thereby moving the moving shaft  9 . 
     In the example embodiment described in  FIGS. 1 to 3 , the rods  1  and  2  are connected in a sliding and coaxial manner with the result that rod  1  is disposed with an internal bore on its second end and the auxiliary rod  2  is disposed with a stud on its first end that is housed in the internal bore of rod  1 . In another embodiment, the second end of rod  1  comprises a stud while the first end of the auxiliary rod  2  comprises an internal bore with the stud of rod  1  being disposed within the internal bore the auxiliary rod  2 . Other arrangements are also possible. 
     In this embodiment the rods are preferably rigid and may be made of metal, plastic, or any other suitable material or combination of materials. 
       FIG. 4  shows a parking brake drive unit with locking device in accordance with another example embodiment. In the example embodiment of  FIG. 4 , on the free end of the main lever  103  there is a button  107  connected to a movement inversion mechanism and connected to a first end of a flexible rod  101  (cable, rope or similar). A second end of rod  101  is housed in a connection device  18 , which internally comprises a rigid member  19  that is connected with or otherwise engageable with the second end of rod  101 . The rigid member  19  slides inside the connection device  18 . The rigid member  19  comprises a receptacle  117  for receiving a moveable shaft  109  of a locking device  104 , and is connected at its other end to a first end of a flexible auxiliary rod  102 . A second end  116  of the auxiliary rod  102  is adapted to directly or indirectly engage with the support member  115  of the catch member  105 , and drive it in a suitable direction to separate the engagement member  113  from the geared sector  114  when the button  107  is pressed. When operated, and through the movement inversion mechanism, it causes a driving of the rod  101 , which is transmitted through the connection device  18  to the auxiliary rod  102 . At the same time auxiliary rod  102  transmits this movement to the catch member  105  in a suitable direction to separate the engagement member  113  from the geared sector  114 . 
     On the main lever  103  is assembled a locking device  104  facing the connection device  18 . When the electric actuation system  108  receives an electrical signal, it is activated and the moveable shaft  109  is withdrawn in a direction away from and out of receptacle  117  of rigid member  19  within the connection device  18 , and when it does not receive an electrical signal it is deactivated and the moveable shaft  109  is extended to reside in the receptacle  117  of the rigid member  19 , which slides inside the connection device  18 . 
     This embodiment of the parking brake drive unit is activated and deactivated in a manner similar to the embodiment of  FIGS. 1-3 . When the parking brake drive unit is activated and the locking device  104  is not activated electrically, the moveable shaft  109  is extended and housed in the receptacle  117  of the rigid member  19 , which slides inside the connection device  18 . In this situation the rod  101  is locked with the result that when the button  107  is pressed, the rod  101  cannot be moved and cannot therefore act on the auxiliary rod  102  as it is connected to the same rigid member  19 , with the result that it does not allow the catch member  105  to be acted on and the engagement member  113  remains engaged in the geared sector  114 . The unit is thus locked and its improper use is prevented. However, the main lever  103  may rotate further upwards in relation to the rest position and therefore tighten the brake device  111  more, as the auxiliary rod  102 , as it is flexible, enables the catch member  105  to pivot in relation to its axis  112  and the engagement member  113  may be moved on the geared sector  114 . 
     In an alternative implementation, a single flexible rod that extends through or across the rigid member  19  is used in lieu of the use of two rods (rod  101  and auxiliary rod  102 ). In such an implementation the single flexible rod is fixed to and traverses the rigid member  19  with a first end portion of the single flexible rod being positioned at or near a proximal end of the main lever and a second end portion of the single flexible rod being coupled with the support member  115  of catch member  105 . 
     In any of the example embodiments, the incorporation of the locking device  4 ,  104  ensures that the parking brake drive unit is a system that remains secure against improper use when the parking brake unit is accessible, for example in an open vehicle with no windows or no top. Advantageously, the number of new components in relation to a standard brake unit is restricted to a locking device  4 ,  104  comprising an electric actuation system  8 ,  108 , a moveable shaft  9 ,  109 , an auxiliary rod  2 ,  102 , a device for connecting the flexible rods  18  for the embodiment of  FIG. 4  and the electrical cables that enable the necessary electrical signal to be conducted. These are simple and inexpensive components and furthermore the electric actuation system  8 ,  108  only acts when the electrical signal reaches it, and this is only required at the point the main lever  3  is deactivated. Furthermore, the moveable shaft  9 ,  109  may move only in an axial direction (although not required) in relation to the electric actuation system  8 , as a result of which this may be a simple system.