Brake operating device

1. A brake operating device, comprising:

a reaction force establishing mechanism that establishes a reaction force against a pedal force applied to a brake pedal,

wherein the reaction force establishing mechanism includes a first reaction force establishing mechanism, and a second reaction force establishing mechanism,

the first reaction force establishing mechanism includes an elastic member that establishes the reaction force against the pedal force applied to the brake pedal,

the second reaction force establishing mechanism is adapted to increase the reaction force when depressing the brake pedal and with an increasing in a depressing speed of the brake pedal, in comparison with the reaction force established when returning the brake,

the first reaction force establishing mechanism and the second reaction force establishing mechanism are arranged coaxially in series,

wherein the second reaction force establishing mechanism comprises:

a piston held in a cylinder while being allowed to reciprocate in an axial direction in response to a pivotal motion of the brake pedal;

a reaction chamber formed in the cylinder that is divided into a first reaction chamber and a second reaction chamber by the piston;

a fluid held in the reaction chamber; and

a flow path connecting the first reaction chamber and the second reaction chamber, and

wherein the second reaction force establishing mechanism is adapted to increase a flow resistance of the fluid flowing through the flow path when depressing the brake pedal, in comparison with the flow resistance of the fluid flowing through the flow path when returning the brake pedal.

2. The brake operating device as claimed in claim 1 , wherein the flow path includes an orifice that increases the flow resistance of the fluid.

3. The brake operating device as claimed in claim 2 , wherein the orifice includes:

a diametrically smaller first orifice that always connects the first reaction chamber and the second reaction chamber; and

a diametrically larger second orifice that is opened when depressing the brake pedal.

4. The brake operating device as claimed in claim 3 , further comprising:

a check valve that selectively opens and closes the second orifice.

5. The brake operating device as claimed in claim 2 ,

wherein the orifice includes:

a diametrically smaller first orifice that always connects the first reaction chamber and the second reaction chamber; and

a diametrically larger second orifice that is opened when depressing the brake pedal, and further comprising:

a check valve that selectively opens and closes the second orifice.

6. The brake operating device as claimed in claim 1 , wherein the flow path includes a flow path penetrating through the piston.

7. The brake operating device as claimed in claim 1 ,

wherein the piston is formed on a piston rod including a first portion and a second portion,

the brake pedal is connected to the first portion of the piston rod through a transmission member, and

the second portion of the piston rod is connected to the first reaction force establishing mechanism.

8. The brake operating device as claimed in claim 7 ,

wherein the first reaction force establishing mechanism comprises a movable cylinder that reciprocates in the axial direction in response to a reciprocation of the piston rod, and a supporting member that guides a leading end of the movable cylinder,

the elastic member includes a first spring interposed between the movable cylinder and the supporting member, and a second spring interposed between the first portion of the piston rod and the movable cylinder, and

an elastic force of the first spring is greater than an elastic force of the second spring.