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EP-4527700-B1 - ISOLATION DEVICE FOR A BRAKE ACTUATING LINKAGE

EP4527700B1EP 4527700 B1EP4527700 B1EP 4527700B1EP-4527700-B1

Inventors

  • GREIF, FELIX P
  • KNOBLOCH, ULRICH
  • KNEER, BERND
  • Wilken, Nils
  • BHATTACHARYA, SHRIDIP
  • Letscher, Jens
  • DENGLER, JONATHAN
  • EDINGER, HOLGER

Dates

Publication Date
20260513
Application Date
20240819

Claims (10)

  1. Insulating device for a brake actuating linkage, with a cylindrical insulating or damping bushing (32) which comprises an inner cylinder sleeve (34), an outer cylinder sleeve (38) coaxially surrounding the inner cylinder sleeve (34) so as to form an annular gap (36), and an elastic element (40) which fills the annular gap (36) and is fixedly connected to the two cylinder sleeves (34, 38), with a brake-pedal-side linkage section (20) and a brake-valve-side linkage section (24), the two linkage sections (20, 24) engaging the insulating bushing (32) along their cylinder axis (46) on opposite sides (48, 50) in such a way that the elastic element (40) is sheared reversibly under the action of an increasing actuating pressure (F_brake) applied to the linkage sections (20, 24) by parallel displacement of the two cylinder sleeves (34, 38) in relation to each other until a mechanical end stop (52) limiting the parallel displacement is reached.
  2. Insulating device according to Claim 1, characterized in that the brake-valve-side linkage section (24) comprises a plunger (54) which is received in a form-fitting manner by the inner cylinder sleeve (34), wherein the inner cylinder sleeve (34) has a protrusion (56) which projects beyond the elastic element (40) and on which an actuating element (58) surrounding the plunger (54) is supported under the action of the actuating pressure (F_brake) applied to the linkage sections (20, 24).
  3. Insulating device according to Claim 2, characterized in that the plunger (54) is an integral component of the brake-valve-side linkage section (24).
  4. Insulating device according to Claim 2 or 3, characterized in that the actuating element (58) is a threaded nut (68) screwed onto an external thread (66) of the plunger (54).
  5. Insulating device according to at least one of Claims 2 to 4, characterized in that the plunger (54) is mounted longitudinally displaceably along the cylinder axis (46) within the inner cylinder sleeve (34).
  6. Insulating device according to at least one of the preceding claims, characterized in that the brake-pedal-side linkage section (20) comprises a bell-shaped housing (70) for the form-fitting receiving of the insulating bushing (32), wherein a radially surrounding shoulder (72) is formed within the bell-shaped housing (70), said shoulder keeping an inner end face (74) of the inner cylinder sleeve (34) at a distance (d) from an inner housing head end (76) when the elastic element (40) is relaxed.
  7. Insulating device according to Claim 6, characterized in that the mechanical end stop (52) is formed by the inner housing head end (76), by the inner end face (74) of the inner cylinder sleeve (34) coming to rest flat against said housing head end.
  8. Insulating device according to Claim 6 or 7, characterized in that the width of the radially surrounding shoulder (72) is preferably dimensioned such that it does not exceed the wall thickness of the outer cylinder sleeve (38) supported thereon.
  9. Insulating device according to at least one of Claims 6 to 8, characterized in that at the inner housing head end (76) there is a blind hole (80) which is aligned with the profile of the inner cylinder sleeve (34) and has an inner diameter which corresponds thereto or is larger.
  10. Insulating device according to at least one of Claims 6 to 9, characterized in that a fastening stub (82) running along the cylinder axis (46) is formed on the bell-shaped housing (70), in which fastening stub a free end (84) of a connecting rod (86) of the brake-pedal-side linkage section (20) is received, wherein a further external thread (94) is formed along the free end (84) of the connecting rod (86) and is screwed into an internal thread (96) running along the cylinder axis (46) in the fastening stub (82).

Description

The invention relates to an isolation device for a brake actuation linkage. Such a brake actuation linkage, particularly in agricultural tractors, serves to transmit the operating force exerted by the driver via a foot pedal to a control element of a brake valve for the hydraulic actuation of the associated wheel brake devices. Operational vibrations caused by a hydraulic system connected to the brake valve can be transmitted back to the foot pedal via the brake actuation linkage in a manner that is perceptible or unpleasant to the driver. In this context, the rubber dampers typically used for vibration isolation can influence the operating force exerted by the driver via the foot pedal, consequently leading to an undefined or ineffective braking response. The document is state of the art. US 2023/031027 A1 known. In view of this, it is an object of the present invention to provide an improved isolation device of the type mentioned above with regard to the actuation behavior of the foot pedal, which at the same time ensures that an undesirable transmission of vibrations from the brake valve to the foot pedal is reduced. This problem is solved by an isolation device for a brake actuation linkage having the features of claim 1. Accordingly, the isolation device for a brake actuation linkage comprises, in addition to a cylindrical isolation or damping bushing, which includes an inner cylinder sleeve, an outer cylinder sleeve coaxially surrounding the inner cylinder sleeve forming an annular gap, and an elastic element filling the annular gap and firmly connected to the two cylinder sleeves, a linkage section on the brake pedal side and a linkage section on the brake valve side, wherein the two linkage sections engage the isolation bushing along its cylinder axis on opposite sides in such a way that the elastic element is reversibly sheared under the influence of an increasing actuation pressure exerted on the linkage sections, with the two cylinder sleeves being displaced parallel to each other until a mechanical end stop limiting the parallel displacement is reached. When installed, the isolation device is connected with the brake pedal-side linkage section to a foot pedal intended for brake actuation, or with the brake valve-side linkage section to an actuating element of a brake valve for the hydraulic control of associated wheel brake devices. The shear strength of the elastic element is preferably selected such that, when an actuation pressure typical for achieving increased braking deceleration occurs, further parallel displacement is blocked due to the mechanical end stop, thus overriding the function of the elastic element. This leads to a defined and therefore The achievable braking effect is characterized by low-loss actuation of the foot pedal, as is desirable, for example, when performing an emergency braking maneuver. The actuation force required for this is typically on the order of 500 Newtons. In the case of braking operations, as are typical for normal driving, the actuation pressure is below such a critical value, so that the mechanical end stop is not reached and the damping properties of the elastic element remain unaffected. Advantageous further developments of the isolation device according to the invention are set out in the dependent claims. To ensure that the actuating force acting via the brake actuating linkage is directed along the cylinder axis into the insulating bushing, the linkage section on the brake valve side preferably comprises a plunger which is positively engaged with the inner cylinder sleeve, wherein the inner cylinder sleeve has a projection extending beyond the elastic element, against which an actuating element rotating on the plunger is supported under the action of the actuating pressure exerted on the linkage sections. The plunger is in particular an integral part of the linkage section on the brake valve side, wherein a ball stud is formed at an end facing away from the plunger for articulated mounting in a ball receptacle or socket, which is connected to the actuating element of the brake valve. The actuating element can be, in particular, a threaded nut screwed onto an external thread of the plunger. The diameter of the external thread corresponds to the inner diameter of the inner cylinder sleeve, thus creating the desired positive fit between the two parts. Alternatively, the actuating element is an integral part of the plunger and is formed on it as a circumferential collar. In this case, the plunger is unthreaded and runs flat along an inner wall of the inner cylinder sleeve. Furthermore, it is conceivable that the plunger is mounted within the inner cylinder sleeve so as to be longitudinally displaceable along the cylinder axis. This allows, when the brake actuation linkage is installed, the insulating bushing or the elastic element it encompasses to be pre-tensioned to a certain extent by turning the threaded nut, in order to adjust the damping characte