Brake pedal apparatus for automotive vehicle

When a collision detecting mechanism 27 detects a front collision of a vehicle, a clutch mechanism 18 integrally connecting a pedal arm 2 to a push rod lever 15 connecting a push rod 14 of a Master vac 13 is disconnected. Accordingly, even when the push rod 14 is backward moved together with the Master vac 13, the push rod lever 14 strikes the air, so that a collision load does not act on the pedal arm 2.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to a brake pedal apparatus for an automotive
 vehicle.
 2. Description of the Related Art
 A brake pedal apparatus for an automotive vehicle is, for example, as shown
 in Japanese Utility Model Unexamined Publication No. 6-1113, structured
 such that a pedal bracket supporting an upper end portion of a pedal arm
 in a freely rotatable manner is fastened to a dash lower panel and a lower
 surface portion of a dash upper panel connected to the dash lower panel
 and projecting to a vehicle cabin, and that a push rod connected to the
 upper end portion of the pedal arm is forward pressed by stepping on the
 pedal arm, thereby operating a Master vac.
 When the Master vac or the dash lower panel fixing the Master vac is
 deformed to be backward move to the vehicle cabin at a time of a front
 collision of the vehicle, a rotational force in a direction inverse to a
 stepping direction is operated on the pedal arm through the push rod of
 the Master vac. Accordingly, a stepping position of the brake pedal is
 rearward shifted and there is a risk that a feeling of physical disorder
 is generated.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a brake pedal apparatus
 for an automotive vehicle which can prevent a collision load from
 operating on a pedal arm through a push rod of a Master vac at a time of a
 front collision of a vehicle and can avoid a load from operating to a foot
 portion of a driver.
 In order to achieve the object mentioned above, in accordance with the
 present invention, there is provided a brake pedal apparatus for an
 automotive vehicle, comprising:
 a pedal bracket fixed to a dash panel;
 a pedal arm supported by the pedal bracket in a freely rotatable manner;
 a push rod lever supported by the pedal bracket in a freely rotatable
 manner and connected to a push rod; and
 a clutch mechanism integrally connecting the pedal arm to the push rod
 lever at a normal time, and disconnecting the pedal arm from the push rod
 lever when a collision detecting sensor detects a collision.
 In accordance with the present invention, since the pedal arm and the push
 rod lever are integrally connected to each other by the clutch means at a
 normal state, the pedal arm and the push rod lever are integrally rotated
 by a stepping operation of the pedal arm. Accordingly, a Master vac
 operation which corresponds to an operation of a normal brake pedal
 apparatus can be performed.
 On the contrary, when the vehicle collides frontward, the clutch means is
 operated by a detecting effect of the collision detecting means so as to
 disconnect the pedal arm from the push rod lever, so that the Master vac
 is rearward moved. Otherwise, even when the dash panel is deformed to the
 vehicle cabin so that the push rod of the Master vac is rearward moved,
 the push rod lever is rotated so as to strike the air. Accordingly, it can
 be avoided that the collision load is input to the pedal arm.
 In the structure mentioned above, the pedal arm and the push rod lever may
 be supported by the pedal shaft provided in the pedal bracket. Further,
 any one of the push rod lever and the pedal arm may be supported in a
 freely slidable manner in an axial direction of the pedal shaft.
 Further, the clutch mechanism may be constituted by engagement portions
 formed in the pedal arm and the push rod lever and engaging with each
 other, and a positioning mechanism which is positioned so that the
 engagement portions of the push rod lever and the pedal arm are engaged
 with each other at a normal time and is deformed when a load is over a
 predetermined value so as to allow any one of the push rod lever and the
 pedal arm to move so that an engagement between the engagement portions is
 removed in an axial direction of the pedal shaft.
 In accordance with this structure, since the clutch mechanism is structured
 as a mechanical clutch construction by engagement portions formed in the
 pedal arm and the push rod lever and engaging with each other, and a
 positioning mechanism which is positioned so that the engagement portions
 of the push rod lever and the pedal arm are engaged with each other at a
 normal time and is deformed when a load is over a predetermined value so
 as to allow any one of the push rod lever and the pedal arm to move so
 that an engagement between the engagement portions is removed in an axial
 direction of the pedal shaft, a construction is simple and a cost thereof
 is advantageous.
 The engagement portions may be formed on end surfaces of each of boss
 portions of the pedal arm and the push rod lever.
 Further, the engagement portion may be constituted by a hook portion formed
 in any one of the pedal arm and the push rod lever, and the other front
 and rear side edges engaging with the hook portion.
 Still further, the positioning mechanism may be constituted by a clutch arm
 supported by an arm shaft provided in the pedal bracket in parallel to the
 pedal shaft in a freely slidable manner in an axial direction and
 connected to any one of the push rod lever and the pedal arm, and a
 positioning member positioning the clutch arm to a predetermined position
 in an axial direction of the arm shaft and deformed when a load is over a
 predetermined value so as to allow the clutch arm to move in an axial
 direction.
 In accordance with this structure, since the clutch arm of the positioning
 mechanism slides in the axial direction of the arm shaft which is in
 parallel to the pedal shaft, the push rod lever or the pedal arm can be
 smoothly slidden in the axial direction on the pedal shaft, so that the
 clutch operation can be smoothly performed.
 Furthermore, the collision detecting sensor may be constituted so as to
 detect a rearward movement of the pedal bracket due to the collision load.
 Moreover, the collision detecting sensor may comprises a collision
 detecting lever projecting from the pedal bracket and rotated by engaging
 a vehicle body or a vehicle body part positioned closer to the vehicle
 cabin than the dash panel in accordance with a rearward movement of the
 pedal bracket due to the collision load, and a cam mechanism moving the
 clutch arm in a direction that an engagement of the engagement portions is
 removed by the rotation of the collision detecting lever.
 In accordance with this structure, since the collision detecting sensor is
 mechanically composed of the collision detecting lever and the cam
 portion, a construction is simple and a cost thereof is advantageous.
 The collision detecting lever may be formed such as to be supported by the
 arm shaft in a freely rotatable manner, to be projected above the pedal
 shaft and to be rotated by engaging with a lower surface portion of a dash
 upper panel projecting to the vehicle cabin above a dash lower panel in
 accordance with a rearward movement of the pedal bracket due to the
 collision load.
 In accordance with this structure, since the pedal bracket slides rearward
 with respect to the dash upper panel at a time of a front collision of the
 vehicle, a collision detecting operation that the collision detecting
 lever is rotated by the engagement with the lower surface portion of the
 dash upper panel can be securely performed.
 Further, the cam mechanism may be structured so as to be formed on end
 surfaces of each of boss portions of the clutch arm and the collision
 detecting lever, to be engaged with each other, and to move the clutch arm
 in a direction that an engagement of the engagement portion is removed in
 an axial direction of the arm shaft against a positioning force of the
 positioning member by the rotation of the collision detecting lever.
 Still further, the pedal bracket is provided with a restricting portion
 disposed near the collision detecting lever projecting from the pedal
 bracket, preventing the collision detecting lever from rotating in a
 normal state, and allowing the collision detecting lever to rotate when a
 rotating force is over a predetermined load.
 In accordance with this structure, since the restricting portion can
 restrict a rotation of the collision detecting lever at a time of
 assembling the brake pedal apparatus to the vehicle, transporting and
 conveying, the collision detecting lever can be securely held in an
 initial set position. On the contrary, at a time of a front collision of
 the vehicle, since the rotation restriction by the restricting portion is
 removed in the case that the rotational force of the collision detecting
 lever is over a predetermined load, the collision detecting lever can be
 frontward rotated with no problem.
 The positioning member may be constituted by a spring urging the clutch arm
 in an axial direction of the arm shaft.
 Further, a return spring may be disposed between the pedal bracket and the
 push rod lever, thereby giving a rearward rotational force to the pedal
 arm through the push rod lever.
 In accordance with this structure, since the urging force of the return
 spring acting on the pedal arm is removed by disconnecting the push rod
 lever from the pedal arm at a time of a front collision of the vehicle, a
 load acting on the leg portion of the driver can be removed.
 Still further, the pedal bracket may be fixed to at least the dash lower
 panel, and the collision detecting lever may be engaged with the dash
 upper panel connected to the upper side of the dash lower panel and
 projecting to the vehicle cabin at a time of a rearward movement of the
 pedal bracket due to a collision load.
 Furthermore, the dash panel may be constituted by a dash lower panel and a
 dash upper panel connected to the dash lower panel and projecting to the
 vehicle cabin, and the pedal bracket may be fixed so as to stride over the
 dash lower panel and the dash upper panel and may be fixed so as to
 rearward slide with respect to the dash upper panel at a time of a
 rearward movement of the pedal bracket due to the collision load.
 In accordance with this structure, since the pedal bracket rearward slides
 with respect to the dash upper panel when the pedal bracket rearward moves
 at a time of a front collision of the vehicle, an upward motion of the
 pedal bracket is restricted by the dash upper panel, thereby preventing
 the pedal bracket from rearward moving toward a rear, diagonal and upper
 direction around the fixing point to the dash upper panel. As a result,
 the pedal bracket interferes with the steering member adjacently disposed
 in a rear and upper portion of the pedal bracket, so that the steering
 member is prevented from being deformed.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
 An embodiment in accordance with the present invention will be described in
 detail below with reference to the accompanying drawings.
 In FIGS. 1 to 4, reference numeral 1 denotes a bracket, and reference
 numeral 2 denotes a pedal arm having an upper end portion supported by a
 pedal shaft 3 fixed to the pedal bracket 1 in a freely rotatable manner.
 The pedal arm is provided with a pedal pad (not shown) in a lower end
 thereof.
 The pedal bracket 1 is formed so as to have a side surface of an inverted-L
 shape. A front wall 1A of the pedal bracket 1 is fastened to a dash lower
 panel 4 through a bolt 7 and a nut 8. A rear end portion of an upper wall
 1B is fastened to a lower surface portion of a dash upper panel 5
 connected to the dash lower panel 4 and projecting to the vehicle cabin,
 that is, concretely speaking, a vehicle body end bracket 6 connected and
 arranged between the lower surface of the dash upper panel 5 and the rear
 wall through the bolt 7 and the nut 8 in a forward inclined state.
 A cylindrical collar 11 is fitted and arranged in the pedal shaft 3 through
 a bush 10. On the contrary, a cylindrical boss portion 12 is provided in
 an upper end portion of the pedal arm 2. The pedal shaft 3 is rotatably
 fitted to the collar 11 through the boss portion 12.
 Reference numeral 13 denotes a Master vac fitted to a side surface close to
 an engine room of the dash lower panel 4 and generating an oil hydraulic
 pressure in a brake unit (not shown) by pressing a push rod 14 extending
 through the dash lower panel 4 in accordance with a stepping of the pedal
 arm 2.
 The push rod 14 of the Master vac 13 is connected to a lower end of a push
 rod lever 15 supported by the pedal shaft 3 in a freely rotatable manner
 through a pin 16.
 The push rod lever 15 is provided with a cylindrical boss portion 17 in an
 upper end portion thereof and is fitted to the collar 11 of the pedal
 shaft 3 through the boss portion 17 in a freely rotatable and slidable
 manner in an axial direction.
 The pedal arm 2 and the push rod lever 15 are integrally connected by a
 clutch means 18 at a normal state. However, the pedal arm 2 and the push
 rod lever 15 can be disconnected by that the clutch means 18 is operated
 by a detecting operation of a collision detecting means mentioned below.
 Further, in accordance with this embodiment, a return spring (a tension
 spring) 19 is arranged between the pin 16 of the push rod lever 15 and the
 pedal bracket 1, so that a rearward rotational force is given to the pedal
 arm 2 through the push rod lever 15.
 In this embodiment, the clutch means 18 is provided with an engagement
 portion 20 formed on each of end surfaces opposing to each other of the
 boss portion 12 of the pedal arm 2 and the boss portion 17 of the push rod
 lever 15 and engaging with each other, and a positioning means 21 urging
 the push rod lever 15 in a direction that the engagement portion 20 is
 engaged, that is, toward the pedal arm 2 end in an axial direction of the
 pedal shaft 3.
 The positioning means 21 is provided with a clutch arm 22 operating the
 push rod lever 15 in an axial direction of the collar 11, and a spring 23
 serving as a positioning member pressing the clutch arm 22 to one side
 direction and urging the push rod lever 15 in an axial direction in which
 the engagement portion 20 engages.
 The clutch arm 22 is provided with a cylindrical boss portion 24 and a fork
 portion 25. The boss portion 24 is fitted to an arm shaft 26 fixed to the
 pedal bracket 1 in parallel to the pedal shaft 3 through the boss portion
 24 in a freely rotatable and slidable manner in an axial direction of the
 arm shaft 26. The fork portion 25 is engaged with the upper and lower
 portion of the boss portion 17 so as to stride over both the right and
 left side portions on the peripheral edge of the upper end portion of the
 push rod lever 15, and is connected thereto so as to move the push rod
 lever 15 in an axial direction of the collar 11.
 Further, the compression spring 23 is elastically disposed between one side
 wall of the pedal bracket 1 and the boss portion 24 of the clutch arm 22
 on the arm shaft 26.
 Reference numeral 27 denotes a collision detecting means detecting a front
 collision of the vehicle and disconnecting the clutch means 18. In
 accordance with this embodiment, the collision detecting means 27 is
 provided with a collision detecting lever 28 supported by the arm shaft 26
 through the boss portion 29 and having an upper end portion arranged near
 the front portion of the vehicle body end bracket 6 so as to project
 through a window portion 31 in the upper wall 1B of the pedal bracket 1,
 and a cam portion formed in each of the end surfaces opposing to each
 other of the boss portion 29 of the collision detecting lever 28 and the
 boss portion 24 of the clutch arm 22.
 The collision detecting lever 28 is formed so as to engage the front
 surface of the vehicle body end bracket 6 so as to rotate when the pedal
 bracket 1 is rearward moved by the front collision of the vehicle, to move
 the clutch arm 22 in an axial direction of the arm shaft 26 against the
 spring force of the spring 23 by the cam portion 30 due to the rotation,
 and to remove an engagement of the engagement portion 20 of the clutch
 means 18. Accordingly, the spring 23 is formed so as to be deformed when
 the load is over a predetermined value.
 Accordingly, the cam portion 30 is formed as an inclined surface having the
 same desired lead angle on the end surface of the boss portions 24 and 29
 so as to be in close contact with each other.
 Further, in accordance with this embodiment, a bolt through hole 32 formed
 in a long hole to a longitudinal direction in the upper wall 1B of the
 pedal bracket 1 is communicated with the window portion 31. Accordingly,
 when the collision input is operated to the pedal bracket 1 in a backward
 direction at a time of a front collision of the vehicle, the bolt through
 hole 32 slides rearward with respect to the vehicle body end bracket 6.
 Further, when the window portion 31 reach a standing position of the bolt
 7, the window portion 31 comes out from the head portion of the bolt 7,
 and the pedal bracket 1 can separate from the vehicle end bracket 6.
 In FIG. 1, reference numeral 33 denotes a stopper restricting a backward
 rotation of the pedal arm 2, and reference numeral 34 denotes a dash
 insulator provided in a side surface close to the vehicle cabin of the
 dash lower panel 4.
 In accordance with the structure of the embodiment mentioned above, since
 in a normal state, the engagement portion 20 of the clutch means 18 is in
 an engaging state and integrally connects the pedal arm 2 to the push rod
 lever 15, the pedal arm 2 and the push rod lever 15 are integrally rotated
 by a stepping operation of the pedal arm 2. Accordingly, the apparatus can
 operates the Master vac 13 by pressing the push rod 14 in the same manner
 as that of a normal brake pedal apparatus.
 On the contrary, when the vehicle frontward collides so that the Master vac
 13 is interfered by the other functional part within the engine room,
 thereby being pressed rearward, or the dash lower panel 4 is interfered by
 the functional part within the engine room so that the dash lower panel 4
 is deformed to the vehicle cabin and the pedal bracket 1 rearward moves
 together with a deformation of the dash lower panel 4 to the vehicle
 cabin, the collision detecting lever 28 of the collision detecting means
 27 is engaged with the front surface of the vehicle body end bracket 6 so
 as to forward rotate.
 When the collision detecting lever 28 forward rotates, the clutch arm 22 of
 the clutch means 18 moves on the arm shaft 26 in an axial direction
 against the spring force of the spring 23 and the push rod lever 15 is
 moved in a direction that an engagement of the engagement portion 20 is
 removed by the clutch arm 22, so that the push rod lever 15 is
 disconnected from the pedal arm 2.
 As a result, even when the rearward pressing force is operated on the push
 rod lever 15 by the push rod 14 caused by the rearward movement of the
 Master vac 13, only the push rod lever 15 strikes at the air and the
 collision load is not input to the pedal arm 2. Accordingly, it is avoided
 that a feeling of physical disorder is generated due to a load application
 to the foot of the driver stepping on the pedal arm 2 and that a shock is
 affected.
 Particularly, in accordance with this embodiment, since the return spring
 19 of the pedal arm 2 is arranged so as to stride over the pin 16
 connecting the push rod 14 disposed in the lower end portion of the push
 rod lever 15 and the pedal bracket 1, the push rod lever 15 immediately
 rotates to a non-engaging position of the engagement portion 20 by a
 rearward urging force of the return spring 19 so as to make the pedal arm
 2 free when the clutch means 18 is disconnected in a manner mentioned
 above. Further, since the urging force of the return spring 19 to the
 pedal arm 2 is removed, the load does not act on the foot of the driver.
 In this case, as mentioned above, when the vehicle frontward collides and
 the pedal bracket 1 is backward moved, the pedal bracket 1 is provided
 with the bolt through hole 32 provided in the upper wall 1B and the window
 portion 31 projecting the collision detecting lever 28 upward in a
 continuous manner and the pedal bracket 1 is fixed so as to rearward slide
 with respect to the vehicle body end bracket 6. Accordingly, the collision
 detecting operation can be securely performed by rapidly rotating the
 collision detecting lever 28 in accordance with the rearward slide of this
 pedal bracket 1.
 Further, when the pedal bracket 1 is rearward slidden so that the window
 portion 31 reaches a standing position of the bolt 7, the window portion
 31 comes out from the head portion of the bolt 7, so that the pedal
 bracket 1 is removed from the vehicle body end bracket 5. Accordingly, the
 bracket 1 is prevented from backward moving toward a rear, diagonal and
 upward direction around the fixing point to the vehicle body end bracket
 5. Further, the pedal bracket 1 can be prevented from being interfered
 with the steering member (not shown) adjacently disposed above the rear
 portion of the pedal bracket 1 so that the steering member is deformed.
 Still further, as well as the collision detecting means 27 is mechanically
 constituted by the collision detecting lever 28 supported by the arm shaft
 26 and the cam portion 30, the clutch means 18 is also mechanically
 constituted by the engagement portion 20, the clutch arm 22 supported by
 the arm shaft 26 and the positioning means comprising the spring 23.
 Accordingly, the construction can be made simple and a cost thereof can be
 advantageously obtained.
 Furthermore, the spring 23 can absorb a vibration and eliminate a play of
 the clutch arm 22, so that a feeling of a quality can be improved.
 Moreover, since the clutch arm 22 axially slides along the arm shaft 26 in
 parallel to the pedal shaft 3, the push rod lever 15 can be smoothly
 slidden on the pedal shaft 3 in an axial direction, so that the clutch
 operation can be smoothly performed.
 In this case, a cylindrical collar axially deforming when the load is over
 a predetermined value may be used in place of the spring 23 mentioned
 above, and in this case, it is preferable a start of the deformation such
 as a slit in the collar or the like is provided in order to axially deform
 over the predetermined load.
 Further, an electromagnetic clutch can be used for the clutch means 18
 other than the means mentioned above, and a collision sensor normally
 mounted in the vehicle and operating an air bag apparatus can be commonly
 used for the collision detecting means 27.
 Still further, in the embodiment mentioned above, the push rod lever 15 end
 is formed to be slidable, however, the pedal arm 2 end may be formed to be
 slidable.
 In this case, the push rod lever 15 in FIG. 3 is downward extended to be a
 pedal arm, and the pedal arm 2 in FIG. 3 is shortened to be a push rod
 lever.
 FIG. 5 shows a second embodiment in accordance with the present invention.
 In this embodiment, in the upper wall 1B of the pedal bracket 1 in
 accordance with the first embodiment shown in FIGS. 1 to 4, a restriction
 portion 35 for restricting a forward rotation of the collision detecting
 lever 28 at a normal state, and for allowing the forward rotation of the
 collision detecting lever 28 when the rotational force is over a
 predetermined load is provided near the front portion of the collision
 detecting lever 28 upward projecting from the window portion 31 of the
 pedal bracket 1.
 Accordingly, in accordance with the embodiment, since the restricting
 portion 35 can restrict the rotation of the collision detecting lever 28
 at a time when the brake pedal apparatus is assembled to the vehicle, is
 transported and is conveyed, the collision detecting lever 28 can be
 securely held at an initial set position. On the contrary, at a time of a
 front collision of the vehicle, since the rotation restriction by the
 restricting portion 35 can be removed when the rotational force of the
 collision detecting lever 28 is over a predetermined load, the collision
 detection lever 28 can be forward rotated with no problem and the clutch
 mechanism mentioned above can be operated.
 In this case, in this embodiment, the restricting portion 35 is formed in a
 bridge shape all around both side edges of the window portion 31 in the
 pedal bracket 1, as an example, however, the restricting portion 35 may be
 formed such that a projecting portion is formed toward a center portion of
 an opening from both sides of the window portion 31.
 FIGS. 6 and 7 show a third embodiment of the present invention. In this
 embodiment, in the push rod lever 15 in accordance with the first
 embodiment shown in FIGS. 1 to 4, there is provided a hook portion 36
 which connects the front and rear side edges of the pedal arm 2 by
 engaging with them at a normal state, and is removed an engagement at a
 time of disconnecting the push rod lever 15 from the pedal arm 2 by the
 clutch means 18.
 Accordingly, in accordance with the structure of this embodiment, the
 connection strength between the pedal arm 2 and the push rod lever 15 at a
 normal state can be increased.
 In this embodiment, the hook portion 36 is formed close to the push rod 15,
 however, it can be of course formed in the pedal arm 2.