Patent ID: 9321442
Filing Date: 2016-04-26
CPC Classification: B60T

Claim Text:
1. A hydraulic brake cylinder comprising: a cylinder body; a first piston slidably engaged with the cylinder body and operably connected to a brake pedal for sliding along an axis in response to pressing and releasing of the pedal, wherein the first piston is configured to slide in a first direction of the axis when the pedal is pressed, wherein the first piston is configured to slide in a second direction of the axis opposite to the first direction when the pedal is released; the first piston comprising a first outer circumference and a second outer circumference that is different from the first outer circumference and is located in the second direction relative to the first outer circumference; a primary chamber defined between the cylinder body and the first and second outer circumferences of the first piston; a second piston slidably engaged with the cylinder body for sliding along the axis relative to the cylinder body; a first spring interposed between the first piston and the second piston; a secondary chamber defined between the cylinder body and the second piston; a second spring provided within the secondary chamber; a hydraulic line interconnecting the primary chamber and the secondary chamber without any intervening valve, and further interconnecting the primary chamber and the secondary chamber to a wheel cylinder for fluid communication therebetween; the first piston comprising a first abutment portion facing the second piston; and the second piston comprising a second abutment portion facing the first piston, wherein the first piston, the first spring, the second piston and the second spring are arranged in order in the first direction along the axis such that the first piston abuts the first spring which abuts the second piston which abuts the second spring, wherein the first piston is at a no-load position in the axis when the pedal is not pressed, wherein at the no-load position, the first and second pistons are apart from each other such that the first and second abutment portions are apart from each other, wherein, as the pedal is pressed, the first piston is configured to slide in the first direction from the no-load position until the first abutment portion of the first piston reaches and contacts the second abutment portion of the second piston, during which the first spring is configured to be compressed and provide force to the first piston in the second direction, wherein as the first piston slides in the first direction from the no-load position, at least part of the second outer circumference replaces at least part of the first outer circumference in defining the primary chamber such that the primary chamber's volume decreases, wherein, as the pedal is further pressed after the first abutment portion reaches and contacts the second abutment portion, the first piston is configured to slide further in the first direction and to push the second piston in the first direction, during which the second spring is configured to be compressed and provide force to the first and second pistons in the second direction.