Fluid-pressure and analogous brake systems – Speed-controlled – Having a valve system responsive to a wheel lock signal
Reexamination Certificate
2001-09-10
2004-02-03
Lavinder, Jack (Department: 3683)
Fluid-pressure and analogous brake systems
Speed-controlled
Having a valve system responsive to a wheel lock signal
Reexamination Certificate
active
06685280
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a brake system preferably for use with automobiles. In particular, the present invention relates to a brake system for automobiles, in which a braking substance or liquid pressurized by an auxiliary pressure source is adjusted and then supplied for controlling a braking operation of wheels of the automobile in response to the brake stroke of the driver.
BACKGROUND ART
For the automobile brake system, with an increased development of a control system mounted on the automobile and a requirement of stability during driving of an Anti-skid Brake System, referred to as “ABS” hereinafter, and a traction control, instead of a braking operation of a driving person, improved systems for the braking operation of the wheels are available so that an electronic control system reads and then determines an optimal braking condition from the operation of the driving person. Also, some of the systems are equipped with an auxiliary pressure source for the generation of a higher braking pressure in addition to a mechanism for the generation of the braking pressure due to a biasing force applied to a brake pedal by the driving person.
JP 10-86802(A) discloses an example of the above-described brake system, in which a signal that indicates a braking pressure generated by the braking operation of the driving person is transmitted to the controller. In response to the signal, the controller controls a separate pressure generator so that the generator generates and then supplies a braking liquid-pressure to the wheel systems. According to the disclosed system, the liquid pressure generated by the braking operation of the driving person is used only for the generation of the control signal but not used directly for the braking control of the wheel systems.
Also, JP 10-35455(A) discloses another control system. According to the control system, the braking force is calculated based upon a stroke of the pedal. A result of the calculation is then used for an adjustment of a high pressure, generated by the auxiliary pressure source, at a proportional pressure control valve so that a suitably adjusted pressure is transmitted to the wheel systems. In this system, the liquid pressure generated by the pedal operation by the driving person is also used for the braking operation of the wheels.
With reference to the drawings, a conventional brake system for automobiles will be described below.
FIG. 11
illustrates an example of the automobile brake system with an auxiliary pressure source. In this drawing, reference numeral
1
indicates a brake pedal on which the driving person applies a biasing force for the brake control of the automobile. Also, the reference numeral
2
indicates a device (hereinafter referred to a “master cylinder”) for generating a pressure force in the braking substrate or liquid according to the braking operation of the driving person. For this purpose, the master cylinder
2
is fluidly connected with two passages or tubes
3
and
4
to a reservoir
5
for the accommodation of a braking substrate or liquid.
The master cylinder
2
, which is a tandem cylinder with two pistons arranged in a serial fashion within a cylinder, is capable of providing the pressurized liquid in two ways or passages
6
and
16
fluidly connected at respective ends to respective pistons. The passage
6
is fluidly connected to a switching valve
7
and then branched into two sub-passages
8
and
9
. Normally, an electromagnetic valve is preferably used for the valve
7
, although another type of valve may be employed instead. The branched passage
8
is fluidly connected with a right-front brake unit
10
and the other branched passage
9
is fluidly connected with a left-rear brake unit
11
, for example. When the electromagnetic valve
7
is electrically disconnected from a power source, it is fluidly connected with the passage at its portion, e.g., left portion indicated by an arrow with arrowheads at its opposite ends in the drawing, allowing the liquid in the passage
6
to pass therethrough. On the other hand, when the electromagnetic valve
7
is electrically connected with the power source, it is connected with the passage at its another portion, e.g., right portion, prohibiting the liquid in the passage
6
from passing therethrough. Also, sensors
13
and
14
for sensing a pressure of the liquid in the passage
6
are provided in the passage
6
and on the opposite sides of the valve
7
.
Likewise, the passage
16
is connected to an electromagnetic valve
17
and then branched into sub-passages
18
and
19
which are in turn connected with left-front brake unit
20
and right-rear brake unit
21
, respectively. The electromagnetic valve
17
has the same structure and connection as those of the valve
7
. Also, sensors
23
and
24
are arranged on opposite sides of the valve
17
for the sensing of the pressure in the liquid passing therethrough. Further, although the automobile brake system includes other passages and valves for ABS and traction control, they are eliminated from the drawing for clarity.
In operation of the brake system so constructed, in the state shown in
FIG. 11
when the valves are electrically disconnected from the power source, the displacement of the pedal
1
due to the biasing operation of the driving person pressurizes the braking liquid accommodated in the two pistons in the master cylinder
2
, which increases the pressure in the passages. The pressure in the passage
6
is transmitted through the electromagnetic valve
7
and then the passages
8
and
9
into brake units in the right-front and left-rear wheel units
10
and
11
, respectively, where it is used for the braking control of respective wheels. Likewise, the pressure in the passage
16
is transmitted through the electromagnetic valve
17
and passages
18
and
19
into brake units in the left-front and right-rear wheel units
20
and
21
, respectively, where it is used for the braking control of respective wheels.
Afterwards, when the biasing force is removed from the brake pedal, the pressure is removed from the pistons in the master cylinder
2
. This also removes the pressure in the passages
6
and
16
, which releases the wheels from the braking control thereof.
Descriptions will be made to other parts including an auxiliary pressure source of the brake system. The auxiliary pressure source generally indicated by reference numeral
30
includes a motor
31
with an output shaft connected with two pumps
32
. Each pump
32
is fluidly connected at an inlet or suction port thereof through a passage
34
to the reservoir
5
and at an outlet or discharge port through a passage
35
to an accumulator
36
and a sensor
37
for sensing the pressure in the passage. A relief valve
38
is provided for the protection of a disadvantageous rapid increase in pressure within the passages. Also, the passage
35
is fluidly connected to an input port
41
of a proportional pressure control valve
40
which will be described below. The valve
40
has output and return ports
42
and
44
connected with passages
43
and
45
, respectively. The passage
45
is branched from the passage
34
and then terminates at the reservoir
5
.
The passage
43
connected at its one end to the output port
42
of the valve
40
is branched into a passage
46
which is extended through an electromagnetic valve
47
to the passages
8
and
9
, and another passage
48
which is extended through an electromagnetic valve
49
to the passage
18
and
19
. In the drawing, the electromagnetic valve
47
is illustrated to be closed when it is disconnected from the power source. An electronic control device
70
is provided so that it is electrically connected at its terminal indicated by alphabet A to terminals of the motor
31
and the valve
40
, also indicated by alphabet A. For clarity, the connections thereof are eliminated from the drawing. In addition, although not illustrated in the drawing, the control device
70
is electrically connected to all of the sensors
13
,
14
,
Higashimura Hideaki
Miyawaki Yoichi
Nakano Keita
Nishikimi Makoto
Yoshino Masato
Greenblum & Bernstein P.L.C.
Lavinder Jack
Nguyen Xuan Lan
Sumitomo Electric Industries Ltd.
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