Device and Method for Tightening a Safety Belt Serving to Protect Occupants in a Vehicle

• US 20080061619A1
• Filed: 09/20/2005
• Published: 03/13/2008
• Est. Priority Date: 10/05/2004
• Status: Active Grant

• Current Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Original Assignee: Fraunhofer Gesellschaft Zur Foerderung Der Angewandten Forsching E.V.
• Inventors: Fischer, Guido, Hanselka, Holger, Bein, Thilo
• Granted Patent: US 7,802,818 B2
• Time in Patent Office: Days
• US Class Current: 297/480
• CPC Class Codes: B60R 2022/285 using friction surfaces
• CPC Class Codes: B60R 2022/288 with means to adjust or regulate the amount of energy to be absorbed
• CPC Class Codes: B60R 22/3413 operating between belt reel and retractor frame B60R22/4676 takes precedence

Abstract

A belt brake is described for a safety belt for protecting occupants in a vehicle, which belt can be wound onto and unwound from a belt drum mounted rotationally about a belt shaft. A method for locking a safety belt is also described. The invention comprises at least one braking means is mounted to enable displacement thereof along the belt shaft, is connected in a rotationally fixed manner to the belt shaft, and is located between a first and a second thrust bearing. A means is provided which is actively connected to at least the first thrust bearing and according to the winding up or unwinding of the safety belt onto or from the belt drum, the first thrust bearing is forcibly guided along the belt shaft, thereby enabling the first thrust bearing to be transferred from a first position, in which the safety belt is wound on the belt drum and in which an axial distance a, exists between the braking means and at least one thrust bearing, and to a second position, in which the safety belt is at least partially unwound from the belt drum and in which an axial distance a₂ exists between the braking means and at least one thrust bearing where a₂<1₁. At least one actuator element is actuated in the second position to generate a braking force which acts along the belt shaft between the first and second thrust bearings and which is orientated towards the at least one braking means.

Claims

1-24. -24. (canceled)

25. A belt brake for a safety belt serving to protect occupants in a vehicle, which belt can be wound onto and from a belt drum mounted rotationally about a belt shaft, comprising:

at least one braking means displaceably mounted longitudinally to the belt shaft, connected to the belt shaft in a rotationally fixed manner and located between a first and a second thrust bearing;

means, connected to at least the first thrust bearing, for forcibly guiding the first thrust bearing along the belt shaft in response to a winding or an unwinding of the safety belt onto or from the belt drum, to transfer the first thrust bearing from a first position at which the safety belt is wound onto the belt drum and at which an axial distance a₁ exists between the braking means and at least one of the first and second thrust bearings, to a second position at which the safety belt is at least partially unwound from the belt drum and at which an axial distance a₂ exists between the braking means and the at least one thrust bearing, with a₂<

a₁; and

at least one actuator element which, when actuated in the second position, produces a braking force which acts longitudinally on the belt shaft between the first and second thrust bearings and which is directed towards the at least one braking means.

26. The belt brake according to claim 25, wherein the at least one actuator element comprises a material selected from the group consisting of:

a piezo ceramic, a piezo polymer, a electroostrictive ceramic, a electrorheological fluid, a poly marl, a magnetorheological fluid, a shape memory alloy and a shape memory polymer.

27. The belt brake according to claim 25, wherein the actuator element is a piezoelectric stacked actuator.

28. The belt brake according to claim 25, wherein the actuator element, when actuated, undergoes a longitudinal expansion by a dimension that is greater than a₂ and smaller than a₁.

29. The belt brake according to claim 25, wherein the at least one braking means is a multibrake disc which has a brake lining at least on one side.

30. The belt brake according to claim 25, wherein the means is a slide nut with a spindle, with a spindle axis located flush with the belt shaft in the axial direction, and the slide nut is rotationally fixed to the belt shaft, but axially displaceable relative to the belt strap and engages the spindle with threads.

31. The belt brake according to claim 25, wherein the means is a cam plate which is connected in a rotational and an axially fixed manner to the belt shaft and is actively and axially connected to the first thrust bearing by at least one rolling body.

32. The belt brake according to claim 31, wherein the cam plate has a concave running path or a plurality of concave shaped running path segments on a surface facing axially towards the first thrust bearing, in the which segments are guided by at least one rolling body contacting a surface of the first thrust bearing facing towards the cam plate.

33. The belt brake according to claim 25, comprising a plurality of braking means located between the first and second thrust bearings, which do not have individual contact axially in the first position, and in which pairs of the braking means contact each other with a force between each other in the second position.

34. The belt brake according to claim 25, wherein the second thrust bearing is axially fixed to the belt shaft.

35. The belt brake according to claim 25, wherein the first and second thrust bearings, the at least one braking means between the two thrust bearings and the means are located on a section of the belt shaft projecting on one side from the belt drum.

36. The belt brake according to claim 25, wherein in the second position the means is separated from the first thrust bearing and the first thrust bearing is self-inhibiting in the second position.

37. The belt brake according to claim 36, wherein the at least one actuator element is actuable by an energy supply, and an interlocking mechanism is provided which, in a first condition of the energy supply, provides an active connection between the means and the first thrust bearing, and wherein the means moves the first thrust bearing axially in a direction of the second thrust bearing as the safety belt unwinds further from the belt drum, and generates a braking force acting between the two thrust bearings on the braking means.

38. The belt brake according to claim 37, wherein the interlocking mechanism has at least one of a coil or an electromagnet.

39. The belt brake according to one of claim 25, comprising:

pre-crash sensors located on the vehicle enable the at least one actuator element to be actuated.

40. A method of locking a safety belt serving to protect occupants in a vehicle, the belt being wound onto and unwound from a belt drum mounted rotationally about a belt shaft, comprising locking the belt drum with a converter material to which energy is applied and which is brought into contact with a braking means connected to the belt drum in a rotationally fixed manner;

and wherein

in a first condition, the safety belt is wound onto the belt drum and with unbraked winding and unwinding of the safety belt being possible and the safety belt assumes a second condition as a result of at least partial unwinding of the safety belt, in which the converter material locks the belt drum after energy is applied.

41. The method according to claim 40, wherein the converter material is chosen from the group consisting of:

a piezo ceramic, a piezo polymer, a electrostrictive ceramic, a electrorheological fluid, a poly marl, a magnetorheological fluid, a shape memory alloy and a shape memory polymer.

42. The method according to one of claim 40, wherein a piezoelectric stacked actuator is used as the converter material.

43. The method according to claim 40, wherein the converter material longitudinally expands after energy is applied.

44. The method according to claim 40, wherein the applied energy is controlled by data from pre-crash sensors in the vehicle.

45. The method according to claim 40, wherein during the second condition an energy supply for supplying energy to the converter material does not supply sufficient energy to the converter material to cause the drum belt to be locked and the belt drum is locked by an interlocking mechanism to prevent further unwinding of the safety belt.

46. The method according to claim 40, wherein the belt drum is locked by the interlocking mechanism after less than one revolution of the belt drum.

47. The method according to claim 40, wherein the interlocking mechanism has at least one of an coil or an electromagnet.