Brake booster

Details Brake booster Brake booster

2003-04-16

2004-10-12

Lazo, Thomas E. (Department: 3745)

Expansible chamber devices

Abutment connection between working member and power...

C092S188000

Reexamination Certificate

active

06802245

ABSTRACT:

BACKGROUND OF THE INVENTION
The invention relates to a brake booster comprising an input element for actuating the brake booster, which input element at its brake pedal-side end has a receiving sleeve for an actuating rod, wherein a spring sleeve is provided, which is disposed at least partially inside the receiving sleeve and has a substantially axially extending spring element, which cooperates with the actuating rod when the latter is brought into a detent position in relation to the input element and which is actuable in a spring-elastic manner in a radially outward direction.
From WO 00/07862, and corresponding U.S. Pat. No. 6,505,539 which is incorporated by reference herein, a conventional brake booster is known. An input element of the brake booster is designed at its brake pedal-side end as a fork provided with a transverse bore. To couple a brake pedal lever to the input element, the brake pedal lever, which is likewise provided with a transverse bore, is introduced into the fork and connected by means of a transverse bolt to the fork. The transverse bolt is then secured to prevent it from accidentally falling out.
From DE 33 07 888 A1, which is incorporated by reference herein, a further brake booster is known. Said brake booster has a load transmission arrangement with an input element, which at its end facing the brake pedal has a sleeve-shaped receiver for an actuating rod, which is actuable by means of the brake pedal. The shell of the sleeve-shaped receiver of the input element is provided with an opening, through which a spring element extends in radial direction. The spring element has two spring portions projecting into the interior of the sleeve-shaped receiver as well as two limbs embracing the radially outer side of the receiver. To couple the actuating rod to the input element, the actuating rod is inserted into the sleeve-shaped receiver until the spring portions projecting into the interior of the sleeve-shaped receiver latch into a peripherally extending groove of the actuating rod.
The free spring end of the spring element opposes axial loading both in and counter to the actuating direction of the brake booster with, in each case, substantially the same spring force. However, while in the event of axial loading of the free end of the spring element in actuating direction a comparatively low spring force is desirable to enable the actuating rod to be brought without a great expenditure of force into the detent position, in the event of axial loading of the free end of the spring element counter to actuating direction, on the other hand, a comparatively high spring force is desirable in order to prevent the actuating rod from being pulled out of the receiving sleeve. The load transmission arrangement according to DE 33 07 888 A1 is incapable of fully meeting said requirements.
From DE 198 43 316 A1, which is incorporated by reference herein, a further load transmission arrangement comprising a plurality of spring elements is known. The load transmission arrangement comprises an input element, which at one of its two ends has a receiving sleeve for an actuating rod. A spring sleeve comprising a plurality of substantially axially extending spring elements is disposed inside the receiving sleeve in such a way that the spring elements, which are actuable in a spring-elastic manner in a radially outward direction, cooperate with the actuating rod when the latter is brought into a detent position in relation to the input element.
For connecting the spring sleeve to the receiving sleeve, the spring sleeve at its end facing the actuating rod has a radially outwardly extending collar, which cooperates in the load transmission direction of the actuating rod with an end of the receiving sleeve facing the actuating rod. To prevent the spring sleeve from detaching from the receiving sleeve when the spring sleeve is loaded by an axial force counter to the load transmission direction of the actuating rod, the spring sleeve in a portion disposed inside the receiving sleeve has a plurality of extensions, which extend in a radially outward direction. Said extensions are supported against a step in the interior of the receiving sleeve so that the spring sleeve does not detach from the receiving sleeve even when loaded with an axial force counter to the load transmission direction of the actuating rod.
To couple the actuating rod to the input element, the actuating rod is inserted into the receiving sleeve until a spherical head of the actuating rod facing the input element has passed the spring elements and the spring elements engage behind the spherical head. The spring elements, which engage behind the spherical head and cooperate counter to the actuating direction of the actuating rod with the spherical head, guarantee that a force introduced counter to actuating direction into the actuating rod is transmitted from the spherical head to the spring elements and from the spring elements to the receiving sleeve connected to the input element. The actuating rod is consequently reliably coupled to the input element not only in actuating direction but also counter to actuating direction.
The drawback of the load transmission element known from DE 198 43 316 A1 is however that the connection of the spring sleeve to the receiving sleeve is complex and hence cost-intensive. This is due above all to the fact that, for connecting the spring sleeve to the receiving sleeve, an undercut has to be disposed in the deepest portion of the receiving sleeve. Said undercut is used to form the step, with which the radially outwardly extending extensions of the spring sleeve cooperate counter to the actuating direction of the actuating rod.
SUMMARY OF THE INVENTION
The object of the invention is to provide a brake booster which guarantees an improved and, particularly from a manufacturing point of view, more easily realizable connection of the spring sleeve to the receiving sleeve.
Said object is achieved in a brake booster of the type described initially in that the spring sleeve at its brake pedal-side end has a radially outwardly extending portion, which is fastened by means of a bead of the receiving sleeve to the latter. The bead guarantees that both forces introduced in actuating direction and forces introduced counter to actuating direction into the spring sleeve may be reliably transmitted to the receiving sleeve. The bead is moreover extremely inexpensive to realize.
The radially outwardly extending portion of the spring sleeve preferably takes the form of a circumferential or at least in sections circumferential collar. Such a refinement guarantees particularly reliable transmission of forces, which are introduced into the spring sleeve, to the receiving sleeve.
The spring sleeve may comprise two or more spring elements, which cooperate with the actuating rod and surround the radially outer side of the actuating rod. The individual spring elements are expediently separated from one another by slots extending substantially in axial direction. For adjustment of the restoring forces of the spring elements, said slots may at their ends facing the spring sleeve widen in peripheral direction of the spring sleeve. The wider the slots in peripheral direction, the more the restoring forces of the spring elements decrease. This is due to the fact that the webs, by which the spring elements are connected to the spring sleeve, become progressively thinner. According to a preferred embodiment of the invention, the widened portions of the slots at their ends facing the spring sleeve take the form of circular recesses. The slots consequently open at their ends facing the spring sleeve into circular recesses. By means of the diameter of the circular recesses it is likewise possible to exert an influence upon the restoring forces of the spring elements.
According to a preferred embodiment of the invention, the spring element cooperates, e.g. via its free end which is actuable in a spring-elastic manner in a radially outward direction in relation to the receiving sleeve, with a first oblique face

Affiliated with

Also associated with

Rating

Brake booster does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Brake booster, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Brake booster will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3300843