Rotary pump with better fluid sealing structure and brake apparatus having same

A brake apparatus having a rotary pump for supplying brake fluid to a wheel cylinder to make brake fluid pressure at the wheel cylinder higher than brake fluid pressure at a master cylinder, the rotary pump comprising:

• an outer rotor provided with inner teeth at an inner circumference thereof;
• an inner rotor provided with outer teeth at an outer circumference thereof, the outer teeth being in mesh with the inner teeth so as to constitute a plurality of teeth gap portions therebetween;
• a drive shaft fitted to the inner rotor with a clearance between the drive shaft and the inner rotor for rotating the inner rotor together with the drive shaft;
• and
• a casing provided with a rotor room where the inner and outer rotors are rotatably contained, a center bore communicating with the rotor room in which the drive shaft is rotatably housed and intake and discharge ports communicating respectively with the teeth gap portions, the rotor room being provided with a first closed region on a side of the teeth gap portion whose volume is largest and a second closed region on a side of the teeth gap portion whose volume is smallest and each of the first and second closed regions being operative for holding brake fluid pressure difference between the intake and discharge ports, wherein brake fluid is sucked from the intake port, being compressed through the teeth gap portions and discharged from the discharge port when the drive shaft is driven;
• wherein the casing is comprised of first and second side plates having respective center bores in which the drive shaft is housed and a center plate having a bore where the inner and outer rotor are contained, the center plate being put between the first and second plates for constituting the rotor room;
• and further wherein an inner wall of the bore of the center plate facing the outer circumference of the outer rotor is provided with two recessed portions and a lateral sealing member is housed in each of the recessed portions for preventing brake fluid communication from the discharge port side to the intake port side in the outer circumference of the outer rotor, the lateral sealing member having a portion whose length in an axial direction of the drive shaft being larger than the thickness of the center plate before the lateral sealing member is put between and loaded by the first and second side plates.