Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1999-10-05
2001-08-14
Oberleitner, Robert J. (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C418S171000, C277S361000
Reexamination Certificate
active
06273527
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based upon and claims the benefit of priority of Japanese Patent Applications No. H.10-284227 filed on Oct. 6, 1998, No. H.10-284228 filed on Oct. 6, 1998, No. H.11-106911 filed on Apr. 14, 1999, and No. H. 11-224499 filed on Aug. 6, 1999, the contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a rotary pump with better fluid sealing structure and a brake apparatus having the same. In particular, the present invention is preferably applied to an internal gear pump such as a trochoid pump or the like for brake apparatus for vehicles.
2. Description of Related Art
A rotary pump, for example, an internal gear pump, is comprised of a drive shaft to be driven by a motor, an inner rotor and an outer rotor to be rotated by the drive shaft and a casing for containing the drive shaft and the inner and outer rotors. The inner and outer rotors contained in the casing form a plurality of teeth gap portions constituted by inner teeth portions of the outer rotor and outer teeth portions of the inner rotor which are in mesh with each other. An intake port and a discharge port are disposed on opposite sides of a pump center line passing through the respective rotation axes of the inner and outer rotors.
When the drive shaft is rotated for driving the pump, the inner rotor is rotated with the drive shaft with an axis of the drive shaft and, according to the rotation of the inner rotor, the outer rotor is rotated in a same direction as the inner teeth portions of the outer rotor are in mesh with the outer teeth portions of the inner rotor. As the respective volumes of the teeth gap portions between the inner and outer teeth portions are varied in every turn of the rotating inner and outer rotors, fluid is sucked from the intake port and discharged to the discharge port.
In the pump mentioned above, there is a problem that the fluid is likely to leak from a high pressure side to a low pressure side through various clearances or gaps in the casing, since fluid pressure at the discharge port (hereinafter called discharge pressure) is higher than fluid pressure at the intake port (hereinafter called intake pressure) when the pump is driven.
In more details, the high pressure fluid at the discharge port leaks to the low pressure intake port or a clearance between the drive shaft and the inner rotor through clearances between the casing and axial end surfaces of the inner and outer rotors, to the low pressure intake port through a clearance between the casing and an outer circumference of the outer rotor or to the low pressure intake port through teeth top gaps formed by forcing the meshed inner and outer teeth portions open.
To cope with these problems, it is possible to narrow the clearance between the casing and the axial end surfaces of the inner and outer rotors or to diminish the clearance to such an extent that the casing and the axial end surfaces of the inner and outer rotors are always in direct contact with each other. However, even if the clearance is narrower, it is very difficult to prevent the fluid leakage and the extremely diminished clearance causes a mechanical loss due to the increased contact resistance with the casing.
Further, it has been proposed to arrange a sealing member between the casing and all of the axial end surfaces of the rotors to restrain the fluid leakage. This is also likely to cause a mechanical loss due to the larger contact resistance with the sealing member.
Furthermore, to prevent the fluid leakage from the outer circumference of the outer rotor, it has been proposed to arrange sealing member in recessed portions provided at an inner wall of the casing that faces the outer circumference of the outer rotor. However, it is very difficult to provide the thickness of the sealing member (the thickness in an axial direction of the inner and outer rotors) always equal to that of the casing because of manufacturing dimensional errors of the sealing member on the molding or machining processes thereof. If there exists a clearance between the casing and the sealing member due to the dimensional errors, fluid leaks through the clearance.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a rotary pump having a better fluid sealing construction that the fluid leakage through the clearance between the casing and the axial end surfaces of the inner and outer rotors may be effectively prevented with a sealing member having a limited contact resistance with the casing and the rotors.
Generally, the rotary pump is composed of 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, 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 having a first closed region between the intake and discharge ports on a side of the teeth gap portion whose volume is largest and a second closed region between the intake and discharge port on a side of the teeth gap portion whose volume is smallest and each of the first and second closed gap 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.
To achieve the above object, in the rotary pump mentioned above, a transverse sealing member is provided at a transverse clearance between the casing and the axial end surfaces of the inner and outer rotors, the transverse sealing member extending from an outer circumference of the outer rotor, via the first closed region, the inner rotor between the drive shaft and the discharge port and the second closed region, to another circumference of the outer rotor so that brake fluid communication through the transverse clearance from the discharge port to the intake port may be prevented, but the brake fluid communication through the transverse clearance between the outer circumference of the outer rotor and almost all of the teeth gap portions on a side of the discharge port and, further, between almost all of the teeth gap portions on a side of the intake port and the clearance between the drive shaft and the inner rotor may be allowed.
Further, it is preferable to provide the transverse sealing member in a manner that brake fluid communication through the transverse clearance between the outer circumference of the outer rotor and at least one of the teeth gap portions on the side of the intake port may be allowed.
Furthermore, it is preferable that 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, wherein each of the first and second side plates is provided with grooved portion extending from the outer circumference of the outer rotor, via the first closed region, the inner rotor between the drive shaft and the discharge port and the second closed region, to the other circumference of the outer rotor and the transverse sealing member is housed in each of the grooved portions.
Preferably, the inner and outer rotors are arranged to be in mesh with each other so that brake fluid in the teeth gap portion or teeth gap portions falling within the first closed region may be com
Fuchida Takeshi
Harada Tomoo
Morikawa Toshiya
Satou Takashi
Shinkai Hiroyuki
Denso Corporation
Oberleitner Robert J.
Pezzlo Benjamin A.
Pillsbury & Winthrop LLP
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