Elastic body apparatus especially intended for an anti-lock brake system

An elastic body apparatus includes a pneumatic pressure sealing member formed of a hollow flexible material and sealing therein a high pressure pneumatic gas, a movable member driven by an external force against the pressure of the pneumatic pressure sealing member, a fixed shell enveloping a fixed portion of the pneumatic pressure sealing member, and an elastic shell having plate spring portions for applying a spring force in the same direction as the pressing direction of the pneumatic pressure sealing member to the movable member, and disposed at a position enveloping a displacing portion of the pneumatic pressure sealing member. The elastic shell serves as a shell and a spring body, and even if the pressure of the pneumatic pressure sealing member is increased, the pneumatic pressure sealing member is prevented from being deformed in excess of a normal level, and the pressure is transmitted to the movable member through the pneumatic pressure sealing member.

BACKGROUND OF THE INVENTION 
1. Field or the Invention 
The present invention relates to an improved elastic body apparatus. More 
particularly, it relates to an elastic body apparatus used, e.g., in the 
suspension system for an automobile, or a liquid pressure regulator for an 
anti-lock brake thereof, etc. 
2. Description of the Prior Art 
Liquid pressure control devices for anti-lock brakes are well known in the 
art. See, for example, U.S. Pat. No. 4,600,245 and Canadian Patent No. 
1,256,966. 
As the elastic body apparatus used for a suspension system or the like for 
automobiles, various devices have been heretofore known which use a spring 
force of compressed air sealed by a flexible member. However, the prior 
art as noted above has problems. For example, in the case where a set load 
of the spring force is increased, if the effective pressure receiving area 
is increased, miniaturization thereof cannot be attained. In addition, if 
a pressure-resisting strength of a flexible member is increased so that a 
high pressure of compressed air may be used, it becomes difficult to 
obtain a suitable flexibility. 
FIG. 4 shows an elastic body apparatus which uses both a pneumatic spring 
and a coil spring in order to obtain a great spring force in a small-sized 
device, the apparatus being applied to a liquid pressure regulator or 
control device for an anti-lock brake. 
A master cylinder 2 actuated by application of a brake pedal 1 is connected 
to an end brake 6 via a liquid pressure regulator 5 by brake tubes 3 and 
4. The liquid pressure regulator 5 houses a movable liquid pressure 
regulating piston 7 and a pressure differential responsive piston 8 formed 
integral therewith. The liquid pressure regulating piston 7 is slidably 
received within a small diameter cylinder 9 and the pressure differential 
responsive piston 8 is slidably received within a large diameter cylinder 
10. Pistons 7 and 8 are provided with annular seals 11, 12 and 13, 14, 
respectively. 
A lid member 15 is secured at the upper portion of the liquid pressure 
regulator 5, and a pneumatic pressure chamber 16 is formed between the lid 
member 15 and the pressure differential responsive piston 8. Gas having a 
predetermined pressure is sealed into the pneumatic pressure chamber 16, 
and a coil spring 17 is also inserted compressible with a predetermined 
mounting load. The pneumatic pressure chamber 16 and the coil spring 17 
constitute an elastic body apparatus which downwardly urges the pressure 
differential responsive piston 8 (a movable member) and the liquid 
pressure regulating piston 7. 
At the lower portion of the liquid pressure regulator 5 are provided an 
input hole or inlet 18, a valve chamber 19, a liquid pressure regulating 
chamber 20 and an output hole or outlet 21, the input hole 18 and the 
output hole 21 being connected to the brake tube 3 and the brake tube 4, 
respectively. An opening and closing valve 22 is mounted between the valve 
chamber 19 and the liquid pressure regulating chamber 20, the valve 22 
being opened, in a normal state, by being pushed down by a pin 23 secured 
to the lower end of the liquid pressure regulating piston 7. A spring 24 
serves to urge or bias valve 22 in a direction toward its "closed" 
position. 
An annular liquid pressure chamber 25 is formed below the pressure 
differential responsive piston 8, the chamber 25 being connected to an 
electromagnetic valve means 27 by means of a liquid pressure tube 26. The 
electromagnetic valve means 27 is turned ON and OFF by an electronic 
control unit (not illustrated). An inlet side of the electromagnetic valve 
means 27 is connected to a discharge side of a pump 29 through a supply 
pipe 28, and a release side thereof is connected to a liquid tank 31 of 
the pump 29 through a conduit 30. 
In the vehicle being operated, when the brake pedal is stepped on or 
depressed by the driver, the brake liquid pressure produced in the master 
cylinder 2 is supplied to the end brake 6 via the brake tube 3, the input 
hole 18, the valve chamber 19, the liquid pressure regulating chamber 20, 
the output hole 21 and the brake tube 4 to effect braking operation. 
However, when the aforesaid brake liquid pressure is excessively supplied 
with respect to a proper friction between the tires and the road surface 
and the wheels tend to lock, the electromagnetic valve means 27 is turned 
ON by the ON-signal of the electronic control unit (not shown), and the 
liquid pressure of the pump 29 is supplied to the liquid pressure chamber 
25. 
When the pressure differential responsive piston 8 is moved upward, due to 
the liquid pressure supplied to the liquid pressure chamber 25, against 
the pressure of the pneumatic pressure chamber 16 and the spring force of 
the coil spring 17, the internal volume of the liquid pressure regulating 
chamber 20 is enlarged and, at the same time, the valve 22 is closed. As a 
result, the excessive supply from the master cylinder 2 to the end brake 6 
is cut off, the brake liquid pressure of the end brake 6 is reduced, and 
the locking of the brake is avoided. When the electromagnetic valve means 
27 is turned OFF by the OFF-signal of the electronic control unit, the 
supply of liquid pressure from the pump 29 is cut off. When the liquid 
pressure of the liquid pressure chamber 25 is released to the liquid tank 
31, the pressure differential responsive piston 8 and the liquid pressure 
regulating piston 7 are moved downward by the pressure of the pneumatic 
pressure chamber 16 and the spring force of the coil spring 17. The brake 
liquid pressure of the end brake 6 is increased by the compression of the 
liquid pressure regulating chamber 20. 
However, the prior art as described above has problems. Corrosion on the 
inner wall surfaces of the large diameter cylinder 10 can build up over 
time. Scratches caused by upward and downward movement of the pressure 
differential responsive piston 8 also occur on the inner wall surfaces of 
the large diameter cylinder 10. In addition, dust or the like may enter 
between the seals 13, 14 and the inner wall sliding surface to impair 
sealing properties of the pneumatic pressure chamber 16. As a result, the 
pressure of the pneumatic chamber 16 is lost to vary the spring force, and 
when the air pressure sealed is set to a large value, the sliding 
resistance of the seal 14 increases to impair the quick-responsiveness of 
the pressure differential responsive piston 8. Moreover, when the mounting 
load of the coil spring 17 is increased, the apparatus become difficult to 
be miniaturized. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide an elastic body 
apparatus, which is small in size, affords a large spring force, provides 
excellent sealing properties and durability of a pneumatic pressure 
chamber and maintains a quick-responsiveness of the movable member. 
It is a further object of the present invention to provide such an elastic 
body which is especially useful as a control device for an anti-lock brake 
system. 
These and other related objects are achieved according to the present 
invention by the provision of an elastic body apparatus which comprises a 
pneumatic pressure sealing member formed of a hollow flexible material and 
sealing therein a high pneumatic gas, a movable member driven by the force 
applied from outside against the pressure of said pneumatic pressure 
sealing member, a fixed shell enveloping a fixed portion of said pneumatic 
pressure sealing member, and an elastic shell having a plate spring 
portion for applying a spring force in the same direction as the urging 
direction of said pneumatic pressure sealing member to said movable member 
and disposed at a position enveloping a displaced portion of said 
pneumatic pressure sealing member. As a result, the elastic shell serves 
as the shell and the spring body, and even if the pneumatic pressure of 
the pneumatic pressure sealing member is increased, a deformation of the 
pneumatic pressure sealing member in excess of a normal state may be 
prevented to transmit a pneumatic pressure to the movable member via the 
pneumatic pressure sealing member.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, FIG. 1 illustrates one embodiment of the 
present invention applied to a liquid pressure regulator for an anti-lock 
brake used in automobiles and other vehicles. A master cylinder 33 
actuated by application of a brake pedal 32 is connected to an end brake 
37 via a liquid pressure regulator or control device 36 by brake tubes 34 
and 35. 
A liquid pressure regulating piston 39 and a pressure differential 
responsive piston 40 (corresponding to a movable member of the present 
invention) formed integral therewith are received within a housing or body 
38 of the liquid pressure regulator 36 for vertical reciprocable movement 
therein. Housing 38 includes an upwardly opened, relatively small diameter 
cylinder 41 with which liquid pressure regulating piston 39 slidably 
contacts and an upwardly opened, relatively large diameter cylinder 42 
with which pressure differential responsive piston 40 slidably contacts. 
Pistons 39, 40 are provided with annular seals 45, 46 and 44, 
respectively. The upper end of cylinder 42 is provided with an opening 43. 
An inverted bowl-like fixed shell 47 covering the opening 43 is fixedly 
mounted above housing 38. Fixed shell 47 is provided with an internal 
annular shoulder 48. Pressure differential piston 40 is provided at its 
top end with a shoulder 49 having an abutment surface 50. An inwardly 
compressible elastic shell 51 is disposed between shoulder 48 and abutment 
surface 50 (which will be described later with reference to FIGS. 2 and 
3), which is approximately semi-spherical in shape and is employed to bias 
or urge the pressure differential responsive piston 40 in a downward 
direction. 
Fixed shell 47 and elastic shell 51 surround a rubber, spherical hollow 
pneumatic sealed pressure sealing member 52 having a pneumatic pressure 
chamber 53 filled with compressed air having a predetermined pressure via 
plug 54. Pneumatic pressure sealing member 52 has a fixed portion 55 
pressing against the inner surface of fixed shell 52 as a result of the 
pressure generated by the compressed air and a displacing portion 56 
pressing against the elastic shell 51 which becomes deformed when the 
elastic shell 51 is compressed. A sheet member 57 made of a synthetic 
resin is inserted between the displacing portion 56 and the elastic shell 
51. The displacing portion 56 is protected by the sheet member 57 from 
being partly abnormally deformed and inflated in the region of a slit 
portion 58 formed in the elastic shell 51. At the same time, the 
compressed air pressure of the pneumatic pressure chamber 53 is 
transmitted to the abutment surface 50 through the displacing portion 56, 
the sheet member 57 and the elastic shell 51. The aforementioned fixed 
shell 47, elastic shell 51, pneumatic pressure sealing member 52 and sheet 
member 57 constitute an elastic body apparatus. This elastic body 
apparatus is sufficiently strong with respect to the compressed air 
pressure to prevent the pneumatic pressure sealing member 52 from being 
deformed in excess of a normal lever. The pressure differential responsive 
piston 40 is urged downward by the pressure generated by the compressed 
air sealed within pneumatic pressure chamber 53 and the high spring force 
of the elastic shell 51. 
An input hole 59, a valve chamber 60, a liquid pressure regulating chamber 
61 and an output hole 62 are provided at the lower end of housing 38, 
input hole 59 and output hole 62 being connected to the brake tube 34 and 
the brake tube 35, respectively. An opening and closing valve 63 is 
mounted between valve chamber 60 and liquid pressure regulating chamber 
61, and normally disposed in an open position by being biased downwardly 
by a pin 64 fixed to the lower end of the liquid pressure regulating 
piston 39. A spring 65 is disposed in valve chamber 61 for urging the 
valve 63 upwardly toward its closed position. 
Continuous liquid pressure chambers 66 and 67 are formed below the pressure 
differential responsive piston 40 between large diameter cylinder 42 and 
small diameter cylinder 41. Liquid pressure chamber 66 is connected to a 
discharge side of a pump 69 by means of a liquid pressure pipe 68. 
A valve cylinder 70 disposed perpendicular to the liquid pressure chamber 
67 is provided on the right-hand side of the housing 38, and an annular, 
liquid pressure releasing groove 72 connected to a suction side of pump 69 
through a conduit 71 is formed in the valve cylinder 70. A solenoid coil 
73 coaxial with valve cylinder 70 is mounted on the right-hand side of 
valve cylinder 70. A spool valve 74 and a movable core 75 formed integral 
therewith are laterally movably inserted into valve cylinder 70 and the 
solenoid coil 73. Spool valve 74 and movable core 75 are provided with 
liquid passages 76 and 77. When spool valve 74 is at a return position (as 
shown), liquid pressure chamber 67 is released through liquid passages 76, 
77, the liquid pressure releasing groove 72 and the conduit 71. A spring 
78 serves to bias the movable core 75 to the return position (as shown). A 
stroke end member 79 is secured to the solenoid coil 73. 
As seen best in FIGS. 2 and 3, upper edge of the generally semi-spherical 
shell 51 is provided with a contact surface 81 which is intended to press 
against shoulder 48 of fixed shell 47 (as shown in FIG. 1). Elastic shell 
51 has plate spring portions 82 formed therein between radially-extending 
slit portions 58. Each of the plate spring portions 82 is formed at its 
lower extended end with a contact end 83 which presses against the 
abutment surface 50 of the pressure differential responsive piston 40. 
The operation will now be described with reference to FIGS. 1 to 3. When 
the brake pedal 32 is not operated, the pressure differential responsive 
piston 40 is urged downward by the air pressure generated by the 
compressed air sealed within pneumatic pressure sealing member 52 and the 
spring force of the elastic shell 51. Valve 63 is opened by being pushed 
down by the pin 64 secured to the liquid pressure regulating piston 39 at 
the return position shown in FIG. 1. 
When brake pedal 32 is operated by the driver in the vehicle being 
operated, the brake liquid pressure produced in master cylinder 33 is 
supplied to end brake 37 via brake tube 34, input hole 59, valve chamber 
60, liquid pressure regulating chamber 61, output hole 64 and brake tube 
35, whereby the braking operation is effected. During the braking 
operation, the liquid pressure regulating piston 39 tends to be forced 
upward by an increase in liquid pressure of the liquid pressure regulating 
chamber 61. However, since the air pressure in pneumatic chamber 53 and 
the spring force of elastic shell 51 are set to be larger than the maximum 
value of the aforesaid "forcing-up" force, pressure differential 
responsive piston 40 and liquid pressure regulating piston 39 are not 
moved upward, and valve 63 also remains opened. 
When the liquid pressure from master cylinder 33 to the end brake 37 is 
supplied excessively with respect to a proper frictional force between the 
tire and the road, a pump drive signal is provided from the electronic 
control unit (not shown) by deceleration information of the wheel. When 
pump 69 is driven, the liquid discharged from pump 59 is circulated via 
liquid pressure pipe 68, liquid pressure chambers 66, 67, liquid passages 
76, 77, liquid pressure release groove 72 and conduit 71. When the wheel 
is about to lock-up, the solenoid coil 73 is energized by the reduction 
signal (ON signal) provided from the electronic control unit whereby the 
movable core 75 and the spool valve 74 are moved till they contact the 
stroke end member 79 against the action of spring 78. 
When liquid pressure release groove 72 is closed by the aforesaid movement 
of spool valve 74, the circulation of liquid is cut off, the liquid 
pressures of liquid pressure chambers 66 and 67 are increased by the 
discharge force of pump 69, and the pressure differential responsive 
piston 40 and the liquid pressure regulating piston 39 are moved upward 
from the FIG. 1 position against the action of the force generated by the 
air pressure within pneumatic chamber 53 and the spring force of elastic 
shell 51. Simultaneously when the inner volume of liquid pressure 
regulating chamber 61 is enlarged by the aforesaid upward movement, valve 
63 which is effectively "released" from being pushed down by pin 64 is 
closed by the action of spring 65. Accordingly, the excessive supply from 
master cylinder 33 to end brake 37 is cut off, the brake liquid pressure 
of end brake 37 is reduced, and the locking of the brake of the wheel is 
avoided. 
When a pressure-increase signal (OFF signal) is provided from the 
electronic control unit, solenoid coil 73 is deenergized, and movable core 
75 and spool valve 74 are moved leftward (FIG. 1) under the force of 
spring 78. Then, liquid pressure release groove 72 is opened whereby the 
liquid pressures of liquid pressure chambers 66, 67 are released, and the 
circulation of the liquid is restored. Even when the liquid is circulated 
by the drive of pump 69 or even when the drive of pump 69 is stopped by a 
stop signal from the electronic control unit, where the liquid pressure 
release groove 72 is opened by the spool valve 74, the liquid pressure for 
moving upward the pressure differential responsive piston 40 against the 
air pressure and the spring force of the elastic shell 51 is not produced 
in the liquid pressure chambers 66, 67 but the liquid pressure regulating 
chamber 61 is compressed by the spring force. Thereby, when the brake 
liquid pressure of the end brake 37 is increased, the braking operation 
restarts. 
In the upward- and downward movement of the pressure differential 
responsive piston 40 as described above, an extremely quick responsiveness 
is required. However, even if a seal normally used for establishing a high 
pneumatic pressure (which increases the sliding resistance) is not used, a 
high compressed air pressure can be obtained or sealed within pneumatic 
chamber 53. Therefore, the apparatus can be miniaturized, and in addition, 
the moving speed of the pressure differential responsive piston 40 can be 
increased. 
Various modifications of the invention may be made as will be apparent to 
one skilled in the art. For example, the sheet member 57 can be omitted if 
safeguards are taken to prevent the pneumatic pressure sealing member 52 
from being cut or bitten into it. This can be accomplished by making 
smaller the width of the slit portion 58 of the elastic shell 51 or by 
forming the pneumatic pressure sealing member 52 into a thicker-walled 
member. While the plate spring portions 82 have been shown as extending 
from the upper edge portion 80 downward axially of the elastic shell 51, 
it is to be noted that they may be radially extended in upper edge portion 
80 toward the contact surface 81 in which case the upper edge 80 may be 
divided by the slit portions 58. The shape of the fixed shell 47 and the 
elastic shell 51 is not limited to those of the embodiments shown in FIGS. 
1 to 3, but a cylindrical shape and a truncated conical shape, for 
example, may be used. 
Thus, while only one embodiment of the present invention has been shown and 
described, it is obvious that many changes and modifications may be made 
thereunto without departing from the spirit and scope of the invention.