Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
1998-12-11
2001-02-27
Schwartz, Chris (Department: 3613)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
C303S010000, C417S363000
Reexamination Certificate
active
06193329
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a brake system which is applied to an anti-brake skid control (which will be hereinafter referred to as a “ABS control”), and is capable of controlling a traction of road wheels and a yawing rate of an automotive vehicle, and particularly to a brake system having a motor-driven pump.
BACKGROUND ART
Conventionally, it is well known that a brake system which performs an ABS control, is employed with a fluid-pressure control valve capable of reducing, holding, and building up the wheel-brake cylinder pressure, a pump provided for sucking brake fluid drained into the reservoir during the pressure-reduction operation of the fluid-pressure control valve and for discharging the sucked brake fluid toward the upstream side of the fluid-pressure control valve, a damper device provided for dampening pulsation in the brake fluid discharged from the pump, and a motor provided for driving the above-mentioned pump.
One such brake system has been disclosed in Japanese Patent Provisional Publication No. 2-231253.
In the conventional brake system, a plunger, constructing a pump, is slidably accommodated in the housing so that the plunger is arranged in a direction perpendicular to the rotational axis of the motor. A damper and a reservoir are disposed in the housing. A motor is mounted on one side wall of the housing. As regards the structure of installation of the motor on the housing, mounting bolts are arranged parallel to the rotational axis of the motor in the direction perpendicular to the axial direction of the plunger. These mounting bolts are screw-threaded into the corresponding female screw holes opening at the side wall of the housing.
Now then, in recent years, it is desired to small-size and to lighten an unit for an ABS control from the viewpoint of easy mounting of the system on the automotive vehicle. The small-sizing and lightening would be achieved by planning an optimal lay-out of a plunger pump, a damper, a reservoir, and a fluid-pressure control valve, all disposed in the housing of the ABS unit.
On the other hand, in designing for a damper and a reservoir, a volumetric capacity necessary for the damper and a volumetric capacity necessary for the reservoir must be selected, accounting for an enhanced dampening effect with respect to the brake fluid pressure and for an enhanced pressure-reduction effect with respect to the brake fluid pressure. Thus, as a matter of course, the degree of the small-sizing of the damper and the reservoir is limited. As a measure of small-sizing the damper and the reservoir, these elements are located closer to each other in the housing, to enable reduction in the total size of the housing. In this case, it is necessary to prevent the position of each of screw-threaded holes for mounting bolts which are used to mount the motor on the housing from overlapping the installation position of the damper and the installation position of the reservoir. On the other hand, it is also necessary to provide a totally-balanced fastening force at the respective fixed points by properly arranging each mounting device containing a bolt and the corresponding female screw-threaded portion. It is difficult to optimally form screw holes in the housing, while satisfying all of the previously-noted necessary conditions.
Additionally, when the pump motor is driven during the operation of the previously-described plunger pump, the reaction force to the fluid pressure acts in the axial direction of the pump (or the axial direction of the plunger) on the compression stroke of the plunger. Furthermore, the reaction force transmits from the plunger to the rotational axis of the motor and acts in the direction perpendicular to the rotational axis. As a result of this, the rotational axis of the motor oscillates. There is an increased tendency for the system to vibrate. This produces noise in the system. In such a case, the greater the perpendicular distance of the fixed point of the mounting bolt mounting the motor on the housing with respect to the axial line of the pump (the axial line of the plunger), the smaller the rigidity of supporting the motor. It is disadvantageous to noise and vibrations.
Assuming that the fixed point of the motor is aligned with the axial line of the plunger, the rigidity of supporting the motor can be enhanced. It is advantageous to reduction in noise and vibrations. However, the screw holes threadably receiving the mounting bolts and the cylindrical bore accommodating therein the plunger are arranged in the direction of the rotational axis of the motor. Therefore, it is necessary to provide a housing size enough to form the screw hole in a space between the side wall of the housing and the cylindrical bore accommodating therein the plunger. There is a problem that the housing is large-sized.
It is, therefore, in view of the previously-described disadvantages of the prior art, an object of the present invention to provide a brake system which is capable of small-sizing the total size of the system and simultaneously reducing noise and vibrations, by disposing the fixed point of each of mounting bolts capable of mounting a motor on a housing at an optimal position, considering the lay-out of a damper and a reservoir arranged in the housing, in order to ensure a necessary volumetric capacity the damper and a necessary volumetric capacity of the reservoir.
DISCLOSURE OF THE INVENTION
The brake system of the present invention comprises a fluid-pressure generating means provided for generating a brake-fluid pressure depending on a driver's braking action, a brake actuating section connected through a brake circuit to the fluid-pressure generating means for applying a braking force to a road wheel, a fluid-pressure control means disposed in a middle of the brake circuit for reducing, holding, and building up the brake-fluid pressure of brake fluid in the braking-force actuating section, a reservoir disposed in a drain circuit into which the brake fluid is exhausted by the fluid-pressure control means during a pressure-reduction operating mode, a pump sucking the brake fluid in the reservoir and discharging the sucked brake fluid within toward the fluid-pressure generating means rather than the fluid-pressure control means of the brake circuit, a motor being a driving source of the pump, a motor shaft inserted into an inboard drive-shaft hole formed in a housing, and formed on an outer periphery thereof with a cam profile, pump bores constructing part of the pump and arranged symmetrically on a same axial line perpendicular to the motor shaft in a manner so as to sandwich the cam profile therebetween, plungers whose ends are in abutted-engagement with the cam profile, and the plungers respectively accommodated in the pump bores so that the plungers reciprocate according to rotation of the motor shaft, the motor being fixed to an end face of the housing by screwing mounting bolts into screw-threaded holes formed in the housing, and the screw-threaded holes being arranged substantially parrallelly in an axial direction of the motor shaft, and formed in a direction substantially perpendicular to an axis of the pump bore, wherein the screw-threaded holes are located at positions close to the pump bore to such an extent that the screw-threaded holes and the pump bore do not overlap each other when the pump bore is projected in axial directions of the screw-threaded holes.
Therefore, when the motor rotates, the plungers reciprocate in a direction perpendicular to the motor shaft, for sucking the brake fluid in the reservoir and for discharging the brake fluid into the brake circuit. At this time, reaction forces of the fluid pressure act on the plungers, such that the reaction forces are input in the direction perpendicular to the motor shaft. Then, the reaction forces input to the motor shaft are supported by means of the mounting bolts. Under this condition, since the mounting bolts and the screw-threaded holes are arranged to be sufficiently close to the pump bore to such an extent that the mounting
Foley & Lardner
Schwartz Chris
Unisia Jecs Corporation
LandOfFree
Braking device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Braking device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Braking device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2579458