Dual deceleration and pressure-sensitive proportioning valve

A dual proportioning valve assembly (10) for a vehicle braking system comprises a housing (12) having a pair of inlets (29, 30) and outlets (31, 32), a bore (25) within the housing (12) containing a pair of oppositely disposed differential pistons (40, 140) biased apart by a main spring (200). The first and second differential pistons (40, 140) have associated first and second poppet valves (50, 150) which control fluid flow between the respective inlet and outlet. A cage member (60) extends within the first differential piston (40) and is connected with the first poppet valve (50), the cage member (60) extending longitudinally within the bore (25) and having an interior chamber (70) with an inertia-sensing mass (80) therein. The inertia-sensing mass (80) engages a third poppet valve (94) which controls fluid flow between the interior chamber (70) and a variable volume chamber (100) defined by the cage member (60) and a stationary piston ( 160) which engages the cage member (60). The stationary piston (160) abuts a shoulder (13) of the housing (12) and extends into the second differential piston (140) where it is connected with the second poppet valve (150) controlling fluid flow between the respective inlet (30) and outlet (32). The stationary piston (160) and cage member (60) are biased apart by a plunger spring (205).

This invention relates to a dual deceleration and pressure-sensitive 
proportioning valve assembly for the brake system of a vehicle. 
U.S. Pat. Nos. 4,595,243 and 4,652,058 and 4,679,864 disclose proportioning 
valve assemblies which include an inertiasensitive object disposed within 
a reservoir, the reservoir communication by means of a channel with the 
proportioning valve and fluid flow through the channel controlled by a 
valve engaged by the inertia-sensitive object. Co-pending patent 
application No. 944,079 illustrates a proportioning valve assembly 
connected with a torque sensing valve. Copending patent application No. 
799,219 discloses an entirely self-contained deceleration and 
pressure-sensitive proportioning valve assembly which eliminates the 
reservoir and channel and which has a single inlet and outlet. It is 
desirable to provide an entirely self-contained dual deceleration and 
pressuresensitive proportioning valve assembly which does not require a 
reservoir or fluid-containing chamber, and which also eliminates a channel 
between the reservoir and proportioning valve assembly. It is desirable to 
reduce significantly the fluid displacement losses accompanying a 
proportioning valve assembly which includes two proportioning valves 
housed in adjacent bores of the housing. The proportioning valve assembly 
should eliminate or reduce any side-to-side pressure differentials caused 
by each of the separate proportioning valves having their own main 
springs, and also should include improved bleedability. The present 
invention provides a solution by providing an entirely self-contained dual 
deceleration and pressure-sensitive proportioning valve assembly which may 
be disposed anywhere within the brake circuit between the master cylinder 
and wheel brake cylinders. No reservoir or external fluid communication is 
required in order to replenish the dual valve assembly, and the channel 
between the reservoir and proportioning valves is eliminated. The fluid 
displacement losses are significantly reduced by being halved, the 
side-to-side pressure differential is reduced by including only one main 
spring within the assembly, and the proportioning valve assembly has 
improved bleedability. The dual proportioning valve assembly includes two 
pressure responsive assemblies, one operating by displacement and the 
other by loading. Additionally, the proportioning valve assembly includes 
inherent high pressure damping in order to compensate for a "spike" 
application of the vehicle brakes. The invention provides a low cost, 
easily manufactured valve assembly. 
The dual proportioning valve assembly of the present invention comprises a 
housing having a pair of inlets and a pair of outlets, first and second 
differential pistons disposed at opposite ends of a bore within said 
housing and biased apart from one another by resilient means, first and 
second poppet valve means each associated with a respective differential 
piston, a cage member and a stationary piston disposed between said 
differential pistons, the cage member connected with said first poppet 
valve means and extending longitudinally to have an internal chamber with 
an inertia-sensing mass therein, the stationary piston connected with said 
second poppet valve means and engaging the cage member to define therewith 
a variable volume chamber, third poppet valve means disposed at an end of 
said variable volume chamber and engaged by the inertia-sensing mass, the 
valve assembly responsive to inlet and outlet pressures so that the valve 
assembly provides pressures at the outlet reduced from the pressures at 
the inlets, and the inertiasensing mass responsive to deceleration of the 
vehicle in order to effect closure of said third poppet valve means and 
cooperate in reducing pressure at the outlets.

FIGS. 1-4 illustrate the dual deceleration and pressure-sensitive 
proportioning valve assembly of the present invention which is designated 
generally by reference numeral 10. The proportioning valve assembly 10 is 
self-contained entirely within a housing 12 that may be disposed separate 
from the body of the master cylinder (not shown). Copending Application 
Ser. No. 738,116 discloses a pair of pressure responsive assemblies 
disposed within a dual bore housing. The dual bore housing communicates 
with a reservoir containing the inertiasensing mass. It is desirable to 
reduce by at least half the fluid displacement losses, to eliminate the 
reservoir, reduce any side-to-side pressure differential, and improve 
bleedability. The housing 12 contains a stepped bore 25 containing at end 
26 a plug or end closure 27 received threadably therein. Plug 27 has an 
inlet 29 from the primary chamber of the master cylinder and an outlet 31 
communicating with the right rear brakes of the vehicle. End 24 of housing 
12 includes an inlet 30 receiving fluid pressure from the secondary 
pressure chamber of the master cylinder and has an outlet 32 communicating 
with the left rear brake assembly of the vehicle. Housing end 26 and plug 
27 include therein a first differential piston 40 received within plug 
bore 38. Plug bore 38 includes seals 36 which engage the outer periphery 
of first differential piston 40. Outlet 31 communicates with plug bore 38. 
A first pressure responsive assembly 14 includes the first differential 
piston 40 having an interior opening 42 communicating with the inlet 29 by 
means of passageway 45, chamber 48, and radial openings 48. Within 
interior opening 42 is first poppet valve means 50 having a poppet end 51 
abutting an end wall 33 of plug 27. Poppet end 51 is in piston end opening 
44, piston 40 having end slots 46 which permit communication with outlet 
31. The first poppet valve means 50 is biased by a spring 49 away from an 
end 62 of cage member 60, valve end 55 being slidably connected with cage 
end 62. Cage member 60 includes a seal 63 about end 62, the seal 63 
engaging the surface of interior opening 42. End 62 extends longitudinally 
into an enlarged section 61 of cage member 60, the transition between the 
portions including a ball valve seat 65. First differential piston 40 
includes an enlarged diameter section 41 which abuts a wall 23 of plug 27. 
The cage member 60 includes a cage member extension 68 having a seal 
therebetween. Cage member 60 and extension 68 form an interior chamber 70 
housing an inertia-sensing mass 80. Disposed above inertia-sensing mass is 
ball valve member 90 which is retained in position by the inertia-sensing 
mass 80 and its close proximity to seat 65. Extension 68 includes a valve 
opening 69 merging with valve seat 71 controlled by third poppet valve 
means 94. Third poppet valve means 94 is biased by spring 95 positioned on 
mount 96. Mount 96 has openings 97 which permit fluid flow through valve 
opening 69, past valve seat 71, through openings 97 and into a variable 
volume chamber 100. 
At housing end 24, a second pressure responsive assembly 16 includes a 
second differential piston 140 having radial openings 148 which permit 
fluid pressure from inlet 30 to flow to interior opening 142, out end 
opening 144, and through end slots 146 to outlet 32. Second differential 
piston 140 includes thereabout seals 136, and spacers 188 and 189 are 
disposed about second differential piston 140 and engage the interior 
surface of stepped bore 25. Second poppet valve means 150 is disposed 
within the interior opening 142, second poppet valve means 150 having end 
extension 151 engaging the housing wall 133. Second poppet valve means 150 
is biased away from stationary piston or plunger 160 by means of a spring 
147. Stationary piston 160 has an end 143 slidably connected with second 
poppet valve means 150 so that there may be movement therebetween. Second 
differential piston 140 extends into an enlarged diameter section 149 
which has complementary longitudinal openings 151 for receiving therein an 
enlarged diameter section 162 of stationary plunger 160. Stationary 
plunger end 164 includes thereabout seal 166 which provides sealing 
between end 164 and the interior surface of interior opening 142 of piston 
140. First differential piston 40 and second differential piston 140 are 
biased apart by main spring 200. Main spring 200 engages the enlarged 
diameter sections 49 and 149. Plunger spring 205 biases apart the 
stationary plunger 160 and cage member 60. Stationary plunger 160 includes 
an end 167 which contains thereabout a seal 169 and extends within the 
cage member extension 68. Abutment 153 extends radially inwardly of 
extension 68 to engage shoulder 169 of end 167 and retain end 167 within 
extension 68. Stationary plunger end 167 and cage member extension 68 
define the variable volume chamber 100. 
Pressurized brake fluid enters inlet 29 and 30 and exits the associated 
outlets 31 and 32. Pistons 40 and 140 are displaced by fluid pressure 
because of the differential areas defined by the respective exterior and 
interior diameters. Pressurized fluid may flow through the slidable 
connection of poppet valve end 55 with end 62 of cage member 60, past 
valve seat 65 and ball valve member 90 to interior chamber 70, through 
slots 73, valve opening 69, past seat 71, third poppet valve means 94, and 
through mount openings 97 to variable volume chamber 100. The pressurized 
fluid communicated to variable volume chamber 100 is contained entirely 
within the first pressure responsive assembly 14 comprising differential 
piston 40, cage member 60, cage member extension 68, and variable volume 
chamber 100. Pressurized brake fluid received at inlet 30 and exiting 
outlet 32 is contained entirely within second pressure responsive assembly 
16 comprising second differential piston 140 and interior opening 142 
bounded at one end by end 164 of stationary plunger 160. Thus, a spring 
chamber 101 of housing 12 does not contain hydraulic brake fluid therein 
and is vented at atmosphere by vent 110. Vent 110 includes a snap-in 
enclosure member 120 which partially plugs vent 110 and allows ventilation 
therethrough while also providing an abutment for enlarged diameter 
section 162 of stationary plunger 160. Section 162 abuts shoulder 13 of 
housing 12. 
Dual proportioning valve assembly 10 operates in accordance with the 
pressure curves illustrated in FIG. 5, which are the same as the pressure 
curves illustrated in U.S. Pat. No. 4,595,243 and copending Application 
Ser. No. 799,219. During operation, pressure responsive assembly 14 
effects the metering of fluid flow by means of displacement of piston 40. 
The pressure responsive assembly 16 effects the metering of fluid flow by 
means of loading piston 140 so that it does not move until a break point 
is reached. Second poppet valve means 150 remains stationary. Referring to 
FIG. 1, as fluid pressure from the master cylinder (not shown) is 
communicated through inlets 29 and 30 to stepped bore 25, fluid pressure 
is communicated through passage 45, chamber 47, radial openings 48, 
interior opening 42, slots 52, end opening 44, end slots 46, and to outlet 
31. Likewise, fluid pressure at inlet 30 is communicated through radial 
openings 148 to interior opening 142, through slots 152, end opening 144, 
end slots 146, and out through outlet 32. Fluid pressure communicated to 
interior opening 42 may flow through the slidable connection of ends 55 
and 62, by seat 65, and downwardly to variable volume chamber 100. Thus, 
the flow paths are open through out proportioning valve assembly 10 so 
that the output pressure (P.sub.out) equals the input pressure (P.sub.in). 
The input pressure rises as the operator applies the vehicle brakes and if 
deceleration of the vehicle is sufficient to cause inertia-sensing mass 80 
to move up the incline surfaces 77 containing slots 73, then third poppet 
valve means 94 is permitted to move upwardly and close valve seat 71 by 
means of the biasing force of spring 95. In order to provide redundant 
valving and insure that the appropriate restriction of fluid flow occurs, 
ball valve 90 is moved upwardly toward seat 65 by mass 80. As a result, 
pressurized fluid is captured within variable volume chamber 100 so that 
the cage member 60 cannot move downwardly toward housing end 24 and break 
point A of FIG. 5 is attained. The stationary positioning of cage member 
60 maintains first poppet valve means 50 stationary while first 
differential piston 40 moves downwardly and metering of fluid through end 
opening 44 is accomplished. As piston 40 moves downwardly, second 
differential piston 140 moves upwardly against the loading of spring 200 
to cause the metering of fluid flow at end opening 144 (see FIG. 2). The 
input pressure (P.sub.in) to output pressure (P.sub.out) relationship will 
follow the curve A.sub.1, indicative of output pressures communicated to 
the rear wheel brake cylinders of an unloaded vehicle. 
If the deceleration of the vehicle is insufficient to cause tilting of the 
vehicle and/or displacement of the ball 80 up sloped surfaces 77 because 
the vehicle is loaded, then increased input pressure (P.sub.in) exerted on 
the differential area pistons 40 and 140 causes the first differential 
area piston 40 to move downwardly (as shown in FIG. 3). Because of main 
spring 200 disposed between the differential pistons, differential piston 
140 is retained in the previous position as differential piston 40 moves 
downwardly and loads piston 140 via spring 200 in the same manner that a 
height-sensing valve loads an associated piston. As the pressure increases 
and the first differential piston 40 moves downwardly, cage member 60 also 
moves downwardly against the biasing effect of plunger spring 205. Plunger 
spring 205 retains the stationary plunger 160 in place, along with the 
assistance of enclosure member 120. Downward movement of cage member 60 
effects downward movement of first poppet valve means 50 so that there 
continues to be metering of fluid flow at end opening 44. As cage member 
extension 68 moves downwardly, the volume of variable volume chamber 100 
decreases and fluid therein flows through openings 97, past seat 71, 
through valve opening 69, slots 73, chamber 70, past seat 65, the slidable 
connection at ends 55, 62, into interior opening 42, and toward outlet 31. 
The loading of differential piston 140 by means of the downward movement 
of differential piston 40 against main spring 200 causes differential 
piston 140 to maintain a stationary position relative to second poppet 
valve means 150 that corresponds to the position of differential piston 40 
relative to first poppet valve means 50. Thus, the same fluid flow is 
communicated to the respective rear brake assemblies and the input 
pressures equal the output pressures as shown by curve B of FIG. 5. If the 
increased output pressures (P.sub.out) provided to the rear wheel brakes 
causes an increased deceleration of the vehicle such that the 
inertia-sensing mass 80 goes up the inclined surfaces 77 (see FIG. 4) and 
permits closure of third poppet valve means 94, then break point C of FIG. 
5 is reached. The closure of third poppet valve means 94 prevents any 
fluid communication through opening 69 so that pressurized fluid is 
trapped in variable volume chamber 100 and prevents any further downward 
movement of cage member 60. First differential area piston 40 will 
continue to move downwardly as a result of the increased input pressure 
until end opening 44 approaches first poppet valve means 50 and 
correspondingly second differential piston 140 moves upwardly so that end 
opening 144 approaches second poppet valves means 150, and restriction of 
fluid flow by first and second poppet valve means 50 and 150 results in 
the pressure curve C.sub.1 of FIG. 5. 
When the brake application ceases, chamber 100 is replenished by the 
opening of valve seat 71. 
The dual deceleration and pressure-sensitive proportioning valves assembly 
of the present invention may be utilized in a cross-split system or in an 
axle-axle split system. The proportioning valve assembly does not require 
a bypass because an inherent bypass is provided. If one of the branches of 
the split circuit should fail, then there would be less deceleration of 
the vehicle and the poppet valve of the operative branch would stay open 
so that higher brake fluid pressure received from the master cylinder can 
be communicated to the associated brake cylinder. Break point C and curve 
C.sub.1 represent the inherent bypass function characteristic for an 
unloaded vehicle, while break point D and curve D.sub.1 represent the 
bypass characteristic for a loaded vehicle. 
The present invention provides the high pressure damping required in case 
of a "spike" application of the brakes. During a "spike" application of 
the brakes, the fluid within pressure 100 would be communicated toward the 
inlet 29 and outlet 31 as the volume of chamber 100 decreases. The 
presence of chamber 100 and the fluid therein provides damping of any 
quick movement of piston 40 and cage member 60 in response to a "spike" 
application of the brakes. Because the flow of fluid out of variable 
volume chamber 100 would be at a controlled rate, the overshoot tendency 
which may occur when a "spike" application of the brakes occurs, is 
restricted. 
The present invention eliminates completely the need for a reservoir and 
any channel between the reservoir and proportioning valve assembly. 
Because two proportioning valve assemblies are not utilized in 
side-by-side bores, there is reduced any side-to-side pressure 
differentials caused by any differences in the main springs utilized with 
the respective proportioning valve assemblies. The present invention 
utilizes a single main spring 200 which effects an equalizing force on 
each of the differential pistons, and provides the effect of a height 
sensing valve which provides a load on the second differential piston 140 
as the first differential piston 40 moves downwardly. The fluid 
displacement losses are reduced by approximately one-half because a single 
assembly is utilized instead of a pair of pressure responsive assemblies 
in side-by-side bores. Additionally, there is improved bleedability when 
assembly 10 is installed. 
Although this invention has been described in connection with the 
illustrated embodiment, it will be obvious to those skilled in the art 
that various changes may be made in the form, structure, and arrangement 
of parts without departing from the invention and the scope of the claims 
appended hereto.