Input device of vehicle brake system

1. An input device of a vehicle brake system, the input device being disposed as a separate unit from an electric brake actuator, the input device having a portion disposed in an engine room of the vehicle and a brake operation element extending from the portion and through a vehicle firewall, which separates the engine room and a passenger compartment of the vehicle, for being operated by a driver, the electric brake actuator provided for generating a first fluid pressure on the basis of at least an electric signal produced according to operation of the brake operation element, the input device of the vehicle brake system comprising:

a master cylinder for generating a second fluid pressure when the operation of the brake operation element is input into the master cylinder;

a stroke simulator for applying a simulated reaction force, produced by the operation of the brake operation element, to the brake operation element, the stroke simulator and the master cylinder forming an attachment body, with the stroke simulator disposed in parallel to the master cylinder and in communication with the master cylinder; and

a component storage box provided on a portion of the attachment body spaced away from the stroke simulator and having a hollow inside space formed therein, wherein the component storage box houses a sensor unit containing a sensor for detecting the second fluid pressure in a fluid pressure passage, the fluid pressure passage communicating with at least one of the master cylinder and the stroke simulator;

wherein the attachment body has a vent passage formed therein with a first end in communication with the hollow inside space of the component storage box, and a second end in communication with another space formed in the attachment body and facing a surface of the firewall having the input device mounted thereon; and

wherein a gap is formed between the master cylinder and the firewall, and said another space formed in the attachment body opens into the gap to allow air to flow between the vent passage and a passenger compartment of the vehicle through the gap.

2. The input device of the vehicle brake system of claim 1 , wherein the master cylinder has a portion extending through the firewall into the passenger compartment, and the second end of the vent passage is formed close to the master cylinder.

3. The input device of the vehicle brake system of claim 2 , wherein the attachment body is attached to the firewall via a gasket, the gasket extending along an outer periphery of the attachment body.

4. The input device of the vehicle brake system of claim 3 , further comprising a waterproof and breathable filter member disposed at the second end of the vent passage and proximate the firewall.

5. The input device of the vehicle brake system of claim 3 , wherein said another space formed in the attachment body defines a lightening portion, the lightening portion having one side which engages a surface of the gasket or of the firewall having the input device mounted thereon, the second end of the vent passage being in communication with the lightening portion.

6. The input device of the vehicle brake system of claim 5 , wherein the attachment body is formed by casting and the lightening portion is integrally formed therein during the casting process.

7. The input device of the vehicle brake system of claim 1 , wherein the component storage box houses a valve unit containing a valve mechanism for opening and closing the fluid pressure passage communicating with at least one of the master cylinder and the stroke simulator.

8. The input device of the vehicle brake system of claim 1 , wherein said another space formed in the attachment body opens directly into the gap.

9. The input device of the vehicle brake system of claim 1 , wherein the second end of the vent passage extends parallel to the gap.

10. The input device of the vehicle brake system of claim 1 , wherein the portion of the input device disposed in the vehicle engine room is attached to the firewall such that it completely covers one end of the gap facing into the engine room.