Power plants – Pressure fluid source and motor – Pulsator
Reexamination Certificate
2000-04-11
2001-09-04
Look, Edward K. (Department: 3745)
Power plants
Pressure fluid source and motor
Pulsator
C060S560000, C060S574000, C060S594000, C091S382000, C091S37600A
Reexamination Certificate
active
06282896
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an idle stroke shortening device in a brake system for shortening the idle stroke existing in the brake system.
It should be noted that the term “idle stroke” means an idling portion (idle portions) in stroke.
In brake systems employed in various machines and apparatus including vehicles such as automobiles, idle stroke generally exists. The idle stroke is composed of idling portions including a space of a control valve of a brake booster until the control valve is switched, a travelling distance of an output piston of a master cylinder until a hydraulic chamber of the master cylinder is shut off a reservoir, and a traveling distance until wheel cylinders produce braking force of a foundation brake.
The existence of the idle stroke in the brake system makes the stroke of a brake pedal longer.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an idle stroke shortening device in a brake system for shortening the stroke of an operational member even when idle traveling distances exist in the brake system.
For accomplishing the object, in a brake system including an operating member, a master cylinder which is actuated by operation of the operating member to develop master cylinder pressure, and a brake cylinder which develops braking force when the master cylinder pressure is introduced into the brake cylinder, the present invention is characterized by an idle stroke shortening device comprising a travel amplifying mechanism arranged between said operating member and said master cylinder, wherein the travel of said operating member is transmitted to said master cylinder after amplified by said travel amplifying mechanism.
The present invention is characterized in that the brake system includes a booster arranged between said operating member and said master cylinder to boost input force applied by said operating member and output the boosted force to said master cylinder, and wherein said travel amplifying mechanism is arranged between said booster and said master cylinder.
The present invention is further characterized in that said travel amplifying mechanism comprises: a cylindrical cylinder piston which is slidably fitted in an axial hole of said master cylinder; a travel amplifying piston which is slidably fitted in said cylinder piston to press an output piston of said master cylinder; a lever which is supported to said cylinder piston in such a manner as to pivot forward when the travel amplifying mechanism is operative and to pivot rearward when the travel amplifying mechanism is inoperative about one end thereof as a support, or is supported to said cylinder piston in such a manner as to pivot forward about one end as a support after moving forward a first preset travel relative to said cylinder piston when the travel amplifying mechanism is operative and to move rearward for said first preset travel relative to said cylinder piston after pivoting rearward about the end when the travel amplifying mechanism is inoperative, wherein the other end of the lever is in contact with an rear end of said travel amplifying piston and wherein output of said booster is applied to a portion between said one end and said the other end; and a cylinder piston control means which engages said cylinder piston with an inner wall of said axial hole for the slidable fitting of said cylinder piston to block the movement of said cylinder piston when it is in the inoperative position and releases the blockage of the movement of said cylinder piston when said travel amplifying piston moves a second preset travel relative to said cylinder piston.
Furthermore, the present invention is characterized in that the brake system includes a booster arranged between said operating member and said master cylinder to boost input force applied by said operating member and output the boosted force to said master cylinder, and wherein said travel amplifying mechanism is arranged between said operating member and said booster.
In addition, the present invention is characterized in that said travel amplifying mechanism comprises: a cylindrical cylinder piston which is slidably fitted in an axial hole of said booster; a travel amplifying piston which is slidably fitted in said cylinder piston and is connected to an operating rod for switching and controlling the control valve of said booster; a lever which is supported to said cylinder piston in such a manner as to pivot forward when the travel amplifying mechanism is operative and to pivot rearward when the travel amplifying mechanism is inoperative about one end thereof as a support, or is supported to said cylinder piston in such a manner as to pivot forward about one end as a support after moving forward a first preset travel relative to said cylinder piston when the travel amplifying mechanism is operative and to move rearward for said first preset travel relative to said cylinder piston after pivoting rearward about the end when the travel amplifying mechanism is inoperative, wherein the other end of the lever is in contact with an rear end of said travel amplifying piston and wherein input force applied by said operating member is applied to a portion between said one end and said the other end; and a cylinder piston control means which engages said cylinder piston with an inner wall of said axial hole for the slidable fitting of said cylinder piston to block the movement of said cylinder piston when it is in the inoperative position and releases the blockage of the movement of said cylinder piston when said travel amplifying piston moves a second preset travel relative to said cylinder piston.
The present invention is further characterized in that said first preset travel is set larger than the travel of said operating rod until the control valve of said booster is switched.
Furthermore, the present invention is characterized in that said cylinder piston control means comprises an engaging member radially movably supported in said cylinder piston and a groove formed in the inner wall of said axial hole, wherein said engaging member in the inoperative position is disposed between said cylinder piston and said groove to block the movement of said cylinder piston and, when said travel amplifying piston moves said second preset travel relative to said cylinder piston, said engaging member moves radially to come off said groove, thereby releasing the blockage of the movement of said cylinder piston. In the idle stroke shortening device in the brake system of the present invention structured as mentioned above, the travel of the operating member is amplified in the initial state of operation by the travel amplifying mechanism and is then transmitted to the master cylinder, whereby the idle stroke of the operating member caused by various idle portions in stroke in the brake system can be effectively shortened.
Particularly, according to the present invention, the travel amplifying mechanism can be relatively simply structured just by using a lever, two pistons, and an engaging member.
In addition, according to the present invention, the function of amplifying the travel of the operating member by the travel amplifying mechanism is not started until the control valve of the booster is switched and is started after the control valve is switched. Therefore, the force required for operating the brake pedal is not increased until the control valve is switched, thus preventing heavy operation of the brake pedal.
Still other objects and advantages of the invention will in part be obvious and will in part be apparent from the specification.
The invention accordingly comprises the features of construction, combinations of elements, and arrangement of parts which will be exemplified in the construction hereinafter set forth, and the scope of the invention will be indicated in the claims.
REFERENCES:
patent: 4656923 (1987-04-01), Tsuyuki et al.
patent: 4665701 (1987-05-01), Bach
Kobayashi Isao
Ogino Shogo
Wachi Yuji
Bosch Braking Systems Co. Ltd.
Kanesaka & Takeuchi
Look Edward K.
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