Abstract: A conical portion is provided at the tip of a main valve body. When brake fluid hits the conical portion of the main valve body, the brake fluid is bounced back at substantially the same angle at which it hits the conical surface of the conical portion. However, the movement direction of the bounced brake fluid is not largely inclined from the direction that the brake fluid is to be caused to flow. Therefore, the flow resistance is reduced. Further, generatrices of the conical portion agree with tangent lines to the spherical surface and the boundary area between the spherical surface and the conical surface is continuous without a step. Therefore, the brake fluid is rectified by these surfaces when it flows. It is possible to reduce the amount of fluctuation in pressure differential relative to fluctuation in the flow rate of brake fluid.

Abstract: A conical portion is provided at the tip of a main valve body. When brake fluid hits the conical portion of the main valve body, the brake fluid is bounced back at substantially the same angle at which it hits the conical surface of the conical portion. However, the movement direction of the bounced brake fluid is not largely inclined from the direction that the brake fluid is to be caused to flow. Therefore, the flow resistance is reduced. Further, generatrices of the conical portion agree with tangent lines to the spherical surface and the boundary area between the spherical surface and the conical surface is continuous without a step. Therefore, the brake fluid is rectified by these surfaces when it flows. It is possible to reduce the amount of fluctuation in pressure differential relative to fluctuation in the flow rate of brake fluid.