CA1058664A - Master cylinder reservoir with vacuum relief diaphragm - Google Patents
Master cylinder reservoir with vacuum relief diaphragmInfo
- Publication number
- CA1058664A CA1058664A CA310,625A CA310625A CA1058664A CA 1058664 A CA1058664 A CA 1058664A CA 310625 A CA310625 A CA 310625A CA 1058664 A CA1058664 A CA 1058664A
- Authority
- CA
- Canada
- Prior art keywords
- reservoir
- brake fluid
- diaphragm
- containing portion
- level
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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- Transmission Of Braking Force In Braking Systems (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
A brake fluid reservoir includes a main body portion having a cap securing a diaphragm between the body and the cap.
A sensor is mounted to protrude into the reservoir for indicating a predetermined minimum level of brake fluid in the reservoir.
The diaphragm is provided for corresponding movement in response to decrease in the level of brake fluid in the reservoir and also for separating a brake fluid containing portion of the reservoir from an air containing portion. The diaphragm includes an interstice for permitting air in the air containing portion to be drawn into the fluid containing portion under preselected conditions. The brake fluid reservoir may be used in a vehicle brake system including master cylinder connected for fluid communication with the reservoir and with the front and rear brakes of the vehicle.
A brake fluid reservoir includes a main body portion having a cap securing a diaphragm between the body and the cap.
A sensor is mounted to protrude into the reservoir for indicating a predetermined minimum level of brake fluid in the reservoir.
The diaphragm is provided for corresponding movement in response to decrease in the level of brake fluid in the reservoir and also for separating a brake fluid containing portion of the reservoir from an air containing portion. The diaphragm includes an interstice for permitting air in the air containing portion to be drawn into the fluid containing portion under preselected conditions. The brake fluid reservoir may be used in a vehicle brake system including master cylinder connected for fluid communication with the reservoir and with the front and rear brakes of the vehicle.
Description
. BACECGROUNI) OF THE INVENTION
-Field Of The Invention-This invention pertains g¢nerally to brakes and more particularly to safety d~vices for fluid pressure operated brakes.
Discussion Of The Prior Art:
- Vehicular hydraulic brake systems typically includ~ a master cylinder operative in response to force applied to a brake pedal by the vehicle operator. A
reservoir, usually included as part of the master cylinder, retains an excess of brake ~ uid to be used in the system. The brake fluid, being a substantially non-compressible iluid, acts to distribute pressure throughout the system when the brake pedal i9 actuated. Factors such lS as wear on the brake pads or brake ~hoes due to repeated braking applications ultimately require added amounts of fluid in the system. Thus, the level of fluid in the reservoir is gradually lowered as the system requires more and more fluid. A diaphragm, placcd in the reservoir aids in limiting contamination of the fluid due to dirt and other foreign matter which could impede or impain the ~yqtem function and also as the fluid level in the reservoir i9 lowered, the diaphràgm extends do~nward with the fluid level so as to corresp dingly displace the volume of fluid leaving the reservoir.
Fluid level sensors are often used to indicate a predetermined minimum level of fluid in such reservoirs.
O~e such sensor i~ immersed into the fluid and includes a float member which follows the fluid level. Shus th~
float must be free to move in the reservoir in order to .
-- 2 -- . .
~' .
~058664 maintain a fixed position relstive to the lowering fluid level.
Diaphragms, ~uch as hereinabove described can interfere with the movement of the float member and if so will render the sensor unreliable. Also, with space in the reservoir being limited due to the presence of the sensor, the diaphragm is limited in its ability to move correspondingly in order to displace the fluid leaving the reservoir. Thus, further lowering of the fluid level -without a corresponding extension of the diaphragm can cause an undesirable vacuum condition to exist in the reservoir which can prevent the brake system from drawing further amounts of fluid from the reservoir. It would be of benefit, therefore, to provide such a reservoir with a non-vacuum creating and non-float interfering relationship between the fluid level, the sensor and the diaphragm so as to avoit the above-mentioned undesirable conditions.
SUMMARY OF THE INVENTION
This application is a division of Canatian Patent Application Serial No. 266,160 filed November 19, 1976..
It has been found, that novel solutions to the afore-mentionet undesirable conditions can be provided. The invention defined in the parent application provides a brake fluid reservoir comprising: a main body portion; a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetemined minimum level of brake fluid in the reservoir; the fluid level sensor including float means for floating on the surface of the brake fluid;
diaphragm mean~ sealingly secured in the reservoir for correspond-ing movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containlng dap ~
; 10S8664 portion of the reservoir from an air containing portion; means surrounding the float means for malntaining the movement of the diaphragm from interfering engagement with the movement of the float means; the brake fluid level sensor means being: an elongated portion; the float means being movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of the brake fluld in the reservoir; the means surrounding the brake fluid level sensor means being: coil means mounted on the sensor and concentrically spaced around the elongated portion and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the -:
diaphragm spaced from the elongated portion and from the float means.
On the other hand, the invention according to the present application broadly, provides a brake fluid reservoir comprising: a~main body portion; a cap mounted on the,main body;
diaphragm means sealingly secured ln the reservoir for corres-ponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid contain-ing portion of the reservoir from an air containing portion;
normally closed interstice means formed in the diaphragm means, the interstice means being openable for permitting air in the air containing portion to pa~ into the brake fluid containing portion unter preselected conditions; and the preselected conditions being a difference in pressure between the two sides thereof.
Other advantages and novel features of this lnvention will become apparent from the following detailed description of the invention when considered in con~unction with the accompanying ~J 1, ~ _ 4 _ dap/~
drawin gQ .
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings wherein like parts are marked alike:
FIG. 1 illustrates a simplified diagrammatic view of a hydraulic brake sy6tem;
FIG. 2 illustrate6 a cross-sectional side elevation of a portion of the reservoir of the invention having a raised fluid level;
FIG. 3 graphically illustrates a cross-6ectional side elevation of the reservoir of this invention having a loweret fluid level and a fully extended diaphragm;
FIG. 4 graphically illu~trates a cross-sectional side elèvation of the reservoir of this invention having dap/ ~ ~
~058664 a further lowered fluid level beyond the full extension capabilities of the diaphragm;
FlG. 5 illustrates an isometric view of a portion of the diaphragm including a slit or interstice formed therein;
FIG. 6 illustrates a cross-sectional side elevation of a portion of an alternative reservoir of the invention having a raised fluid level; and FIG. 7 graphically illustrates a cross-ssctional side elevation of the reservoir of FIG. 6 having a lowersd fluid level and a fully extended diaphragm.
pESCRIPTION OF THE PREFERRED EMBODI~n~Nr - ~eferring now to the drawings, FIG. i generally illustrates a simplified diagrammatic view of i hydraulic brake system designated 10. Tandem master cylinder 12 is connected for fluid communication with two brake fluid reservoirs formed in a single reservoir housing 14.
~owever, inasmuch as the reservoirs are similar, only one will be shcwn and discussed. Conduit 16 fluidly connects 20 - master cyli~der 12 with front brake wheel cylinders 18 via branch conduits 16a, 16b wherea conduit 20 fluidly ccnnects the master cylindsr with rsar brake whsel cylinders 22 via branch conduits 20a, 20b. ~hen force i9 applied to foot pedal 24 by a vshicls operator, the fluid transmits the pressure to the vehicle brakes.
FIG. 2 illustratQs reservoir housing 14 which includes main body portion 26 preferably cast of iron or some other suitable material having side walls 27 which may be annular or of any ~u~table geometric shape. Top ¢nd 28 terminates at 30 forming an opening whereas bottom _ 5 _ end 32 terminates st end wall 34 including rQplenishing port 36 and vent port 38 for fluid com~unication with master cylinder 12 not shown. Given this basic configuration it can be seen in ~IG. 2 that the main body S portion provides an adequate retainer for fluid such as hydraulic brake fluid 40 as i5 well known.
Cap 42 shown mounted on main portion 26 is preferably of steel and is formed with a flange portion 44 and a dome-like portion 46. An opening 48 is provided in the tome-like portion 46 for accom~odating a fluid level sensor to be discussed later in greater detail. Flange portion 44 is provided for alig~ment with top end 28 of main body portion 26 as is weLl known. A vent or port 50 may be provided in cap 42 to communicate the reservoir to atmosphere.
Diaphragm 52 i8 prefesably of rubber or some suitable resilient synthetic material. The diaphragm is sealingly secured in the seservoir at outer pesiphesy 53 between cap 42 and main body portion 26 such as between top end 28 and flange 44. Diaphragm S2 is convoluted to permit extension thereof dcwnward into main body portion 26 as is well known. Inner pesiphery 54 is secured between - cap 42 and the sensor ad~acent opening 48 of the cap.
A novel inclusion in diaphragm 52 i8 provided at slit os interstice 96 provided in a psrtion of diaphragm 52 insida reservoir 14 in the vicinity of the portion of the diaphragm secured between flange 44 of cap 42 and top end 28 of main body portion 26. Slit 96 remains c~osed due to the inherent resilience of the disphragm matesial and is provided to open when a substantial pressure di~ference exists across diaphragm 52, see FIGS. 2 and 5.
A well kn wn sensor 56 is provided for mounting on the reservoir so as to protrude thereinto to indicate a predetermined minimum level of brake 1uid in the rcservoir.
S ~ain portion 58 of sensor 56 is generally of plastic and includes a first end 60 having a threaded sxtension 62 for extending through dome portion 46. Flange 64 secures inner periphery 54 of diaphragm 52 against dome port~on 46 adjacent opening 48 due to tightening nut 68 threadedly received by threaded extension 62. An elongated extended portion 70 extends downward into the reservoir from flange 64 and ~ncludes cavity 72 extending from open first end 60 downward to terminate at cavity end wall 74 adjacent sensor second end 75, as viewed-in FIG. 2. A well kn~w lS ~agnetically actuated electric switching element 76 is secured in cavity 72 by an epoxy filler or the like and i~ ccnnected to a warning device ~not shown) external to the sensor 56 by wires 78, as i9 well kn w n. ~ sealing boot 80 is mounted ad~acent first end 60 to seal the exposed open first end 60. A pla~tic or other suitsble ~ynthetic material is used to form 8 doughnut-shaped float 82 having opening 84 formed therethrough to be s}idably accommodated by elongated extended portion 70. Float 82 includes mag~etic elements 66 imbeddet therein to cooperatingly actuate element 76 when in proximity tberewith so as to indicate a predetermined minimum level -of fluid in the reservoir.
A novel inclusion in sensor 56 is provided comprising a first annular groove 86 formed in the outer annul~r periphery of flange 46 ad~acent first end 60 and , ~ 7 a second annular groove 88 in elongated extended portion to adjacent second cnd 75. Coil spring 90, preferably of spriDg steel, is substantially of uniform diameter aq it extends d~nward from first end 92 accommodated by flange groove 86 and then diminishes in diamet~r at s~cond end 94 to be accommodated by groove 88. The spring is gr~at enough in both diameter and length to permit fsee movement of float 82 substantially along the length of extended portion 70 into ultimate proxim~ty with element 76 so as to cage float 82 from interferring engagement with diaphragm 52 as illustrated by FIGS. 2, 3 and 4.
FIG. 3 graphically illustrates a portion of reservoir housing 14 including the dcwnwardly extended diaphragm 52 to correspontingly displace the fluid 40 leaving the reservoir. Also, float.member 82 is illustrated as correspondingly follcwing the fluid level.
~ FIG. 4, graphically illustrates a portion of reservoir housing 14 including the further downwardly oxtending diaphragm 52. However, 9ince some of the space in re~ervoir housing 14 is occupisd by sensor 56, diaphragm 52 is limited in its abil~ty to displace.all or practically all of the fluid leaving the reservoir. Thus, further lowering of the level of fluit 40 without a corresponding displacement by diaphragm 52 can cause an undesirable vacuum condition to exist in the reservoir. Of course, such condition can be preselectively controlled in view of varying the diaphragm paramRters. However, due to the inclusion of interstice 96 in diaphragm 52 the sealing : effect of the diaphragm can~be removed under such conditLon- as th diaphra~= ateecpts to Fxtend douov ~dly .
ln accordance with the 1uid level. Under these condition~
a potontial vacuum condition can exist in the brake fl~it containing portion of the reservoir wh&reas the air containlng portion remains substantially at atmospheric pressure. Thus a pressur~ differential may exise across diaphragm 52 sufficient to cause interstice 96 to op~n thus permitting air to pass therethrough fro~ the air containing portion of the reservoir to the bxake fluid containing portion.
In the alternative, FIG. 6 illustrates reservoir housing 14a which includes main body portion 26a preferably of cast iron or some other suitable material hav~ng side walls 27a which may be annular os of any suitabls gaometric ~hape. Top end 28a terminates at 30a forming an opening whereas bottom end 32a term~nates at end wall 34a including replenishing port 36a and vent port 38a fos communication oi' fluid 40a with master cylinder 12 not shown.
Cap 42a shown mounted on main portion 26a is preferibly of steel ant is formed with a flange portion 44a and a tome-like postlon 46a. Flange portion 44a i9 provided for slignment with top end 28a of main body portlon 26a as i~ well known.- A vent or port 50a may be provided in cap 42a to communicate the reservoir to atmosphere.
Diaphsagm 52a iB preerably of rubber or somo suitable sesilient synthetic material. The tiaphragm i~
8eslingly secured in the seservoir at outer periphsry 53a between cap 42a and main body portion 26a such as between top end 28a and flange 44a. Diaphragm 52a is convoluted to permit extension thereof downward into main body portion 26a as i5 well known.
~./ , .
_ 9 _ A novel inclusion in diaphragm 52a is provided at slit or interstice 96a provided in a portion of diaphragm 52a inside reservoir 14a in the vicinity of the portion of the diaphragm secured between flange 44a of cap 42a and top end 28a of main body portion 26a. Slit 96a remains closed due to the inharent resilionce of the diaphragm material and is provided to open when a substantial pressure difference exists across diaphragm 52a.
FIG. 7 graphically illustrates a portion of reservoir 14a including fully downwardly extended diaphragm 52a. However, in certain instances such as where the number of permissible convolutions in the diaphragm may be limited due to space limitations or other factors in the reservoir, diaphragm 52a is limited in its ability to di~place all or practically all of the fluid leaving the reservoir. Thus, further lowering of the level of fluid 40a without a corresponding displacement by diaphragm 52a can cause an undesirable vacuum condition to exist in the reservoir. Of course, as stated before, such condition can be preselectively controlled in view of varying the diaphragm parameters. However, due to the inclusion of lnterstice 96a in tiaphragm 52a, the sealing effect of the diaphragm can be removed under such conditions as the diaphragm attempts to extend d~nwardly in accordanca 2S with the fluid level. Unter these conditions 8 potential yacuum condition can exist in the brake fluid containing portion of the reservoir whereas the air containing portion re~ains substantially at atmospheric pressure. Thus, a pressure differential may exist across diaphragm S2a sufficient to cause interstice 96a to open thus permitting air to pass therethrough from the air containing portion of tho reservoir to the braks fluid containing portion.
In operation, the braks fluid level in th~
reservoir is gradually lowered as the system requires additional amounts of fluid due to factors such as wear on thc brake pads or shoes. Diaphrag~ 52 gradually extends townwardly with the fluid level so as to correspondingly displace the volume of fluid lsaving the reservoir.
As the fluid level decreases, float member 82 correspondingly moves downwardly along extended portion 70 of sensor 56, Due to the caged relationship of float member 82 with respect to diaphragm 52, the float member is permitted to move downwardly along extended portion 70 without experiencing interferring engagement with downwardly moving diaphragm 52.
Once the tiaphragm is fully extended downwardly into the reservoir, an undesirable pressure differential across the diaphragm is avoidsd due to the flexibl~ and resil~ nt nature of the diaphragm material to permlt opening of inter9tice 96 thus permitting atmospheric air to pass therethrough into the brake fluid containing portion from the ais containing portion. Onca the pressure differential across the diaphragm diminishes, the resilience of the diaphragm material permits the interstlce to close.
The foregoing has described a novel brake fluid seservois capable of providing a ncn-vacuum creating and non-float interferring relationship between the fluit level, sensor snd diaphragm'therein.
Obviously, other modifications and variations of . . .
the present lnvention are possible in the light of the above teachings. It i9 therefore to be understood that within thc scope of the appended claims the invention may be practiced othen~ise than as specifically describsd,
-Field Of The Invention-This invention pertains g¢nerally to brakes and more particularly to safety d~vices for fluid pressure operated brakes.
Discussion Of The Prior Art:
- Vehicular hydraulic brake systems typically includ~ a master cylinder operative in response to force applied to a brake pedal by the vehicle operator. A
reservoir, usually included as part of the master cylinder, retains an excess of brake ~ uid to be used in the system. The brake fluid, being a substantially non-compressible iluid, acts to distribute pressure throughout the system when the brake pedal i9 actuated. Factors such lS as wear on the brake pads or brake ~hoes due to repeated braking applications ultimately require added amounts of fluid in the system. Thus, the level of fluid in the reservoir is gradually lowered as the system requires more and more fluid. A diaphragm, placcd in the reservoir aids in limiting contamination of the fluid due to dirt and other foreign matter which could impede or impain the ~yqtem function and also as the fluid level in the reservoir i9 lowered, the diaphràgm extends do~nward with the fluid level so as to corresp dingly displace the volume of fluid leaving the reservoir.
Fluid level sensors are often used to indicate a predetermined minimum level of fluid in such reservoirs.
O~e such sensor i~ immersed into the fluid and includes a float member which follows the fluid level. Shus th~
float must be free to move in the reservoir in order to .
-- 2 -- . .
~' .
~058664 maintain a fixed position relstive to the lowering fluid level.
Diaphragms, ~uch as hereinabove described can interfere with the movement of the float member and if so will render the sensor unreliable. Also, with space in the reservoir being limited due to the presence of the sensor, the diaphragm is limited in its ability to move correspondingly in order to displace the fluid leaving the reservoir. Thus, further lowering of the fluid level -without a corresponding extension of the diaphragm can cause an undesirable vacuum condition to exist in the reservoir which can prevent the brake system from drawing further amounts of fluid from the reservoir. It would be of benefit, therefore, to provide such a reservoir with a non-vacuum creating and non-float interfering relationship between the fluid level, the sensor and the diaphragm so as to avoit the above-mentioned undesirable conditions.
SUMMARY OF THE INVENTION
This application is a division of Canatian Patent Application Serial No. 266,160 filed November 19, 1976..
It has been found, that novel solutions to the afore-mentionet undesirable conditions can be provided. The invention defined in the parent application provides a brake fluid reservoir comprising: a main body portion; a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetemined minimum level of brake fluid in the reservoir; the fluid level sensor including float means for floating on the surface of the brake fluid;
diaphragm mean~ sealingly secured in the reservoir for correspond-ing movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containlng dap ~
; 10S8664 portion of the reservoir from an air containing portion; means surrounding the float means for malntaining the movement of the diaphragm from interfering engagement with the movement of the float means; the brake fluid level sensor means being: an elongated portion; the float means being movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of the brake fluld in the reservoir; the means surrounding the brake fluid level sensor means being: coil means mounted on the sensor and concentrically spaced around the elongated portion and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the -:
diaphragm spaced from the elongated portion and from the float means.
On the other hand, the invention according to the present application broadly, provides a brake fluid reservoir comprising: a~main body portion; a cap mounted on the,main body;
diaphragm means sealingly secured ln the reservoir for corres-ponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid contain-ing portion of the reservoir from an air containing portion;
normally closed interstice means formed in the diaphragm means, the interstice means being openable for permitting air in the air containing portion to pa~ into the brake fluid containing portion unter preselected conditions; and the preselected conditions being a difference in pressure between the two sides thereof.
Other advantages and novel features of this lnvention will become apparent from the following detailed description of the invention when considered in con~unction with the accompanying ~J 1, ~ _ 4 _ dap/~
drawin gQ .
BRIEF DESCRIPTION OF THE DRAWINGS
In the drawings wherein like parts are marked alike:
FIG. 1 illustrates a simplified diagrammatic view of a hydraulic brake sy6tem;
FIG. 2 illustrate6 a cross-sectional side elevation of a portion of the reservoir of the invention having a raised fluid level;
FIG. 3 graphically illustrates a cross-6ectional side elevation of the reservoir of this invention having a loweret fluid level and a fully extended diaphragm;
FIG. 4 graphically illu~trates a cross-sectional side elèvation of the reservoir of this invention having dap/ ~ ~
~058664 a further lowered fluid level beyond the full extension capabilities of the diaphragm;
FlG. 5 illustrates an isometric view of a portion of the diaphragm including a slit or interstice formed therein;
FIG. 6 illustrates a cross-sectional side elevation of a portion of an alternative reservoir of the invention having a raised fluid level; and FIG. 7 graphically illustrates a cross-ssctional side elevation of the reservoir of FIG. 6 having a lowersd fluid level and a fully extended diaphragm.
pESCRIPTION OF THE PREFERRED EMBODI~n~Nr - ~eferring now to the drawings, FIG. i generally illustrates a simplified diagrammatic view of i hydraulic brake system designated 10. Tandem master cylinder 12 is connected for fluid communication with two brake fluid reservoirs formed in a single reservoir housing 14.
~owever, inasmuch as the reservoirs are similar, only one will be shcwn and discussed. Conduit 16 fluidly connects 20 - master cyli~der 12 with front brake wheel cylinders 18 via branch conduits 16a, 16b wherea conduit 20 fluidly ccnnects the master cylindsr with rsar brake whsel cylinders 22 via branch conduits 20a, 20b. ~hen force i9 applied to foot pedal 24 by a vshicls operator, the fluid transmits the pressure to the vehicle brakes.
FIG. 2 illustratQs reservoir housing 14 which includes main body portion 26 preferably cast of iron or some other suitable material having side walls 27 which may be annular or of any ~u~table geometric shape. Top ¢nd 28 terminates at 30 forming an opening whereas bottom _ 5 _ end 32 terminates st end wall 34 including rQplenishing port 36 and vent port 38 for fluid com~unication with master cylinder 12 not shown. Given this basic configuration it can be seen in ~IG. 2 that the main body S portion provides an adequate retainer for fluid such as hydraulic brake fluid 40 as i5 well known.
Cap 42 shown mounted on main portion 26 is preferably of steel and is formed with a flange portion 44 and a dome-like portion 46. An opening 48 is provided in the tome-like portion 46 for accom~odating a fluid level sensor to be discussed later in greater detail. Flange portion 44 is provided for alig~ment with top end 28 of main body portion 26 as is weLl known. A vent or port 50 may be provided in cap 42 to communicate the reservoir to atmosphere.
Diaphragm 52 i8 prefesably of rubber or some suitable resilient synthetic material. The diaphragm is sealingly secured in the seservoir at outer pesiphesy 53 between cap 42 and main body portion 26 such as between top end 28 and flange 44. Diaphragm S2 is convoluted to permit extension thereof dcwnward into main body portion 26 as is well known. Inner pesiphery 54 is secured between - cap 42 and the sensor ad~acent opening 48 of the cap.
A novel inclusion in diaphragm 52 i8 provided at slit os interstice 96 provided in a psrtion of diaphragm 52 insida reservoir 14 in the vicinity of the portion of the diaphragm secured between flange 44 of cap 42 and top end 28 of main body portion 26. Slit 96 remains c~osed due to the inherent resilience of the disphragm matesial and is provided to open when a substantial pressure di~ference exists across diaphragm 52, see FIGS. 2 and 5.
A well kn wn sensor 56 is provided for mounting on the reservoir so as to protrude thereinto to indicate a predetermined minimum level of brake 1uid in the rcservoir.
S ~ain portion 58 of sensor 56 is generally of plastic and includes a first end 60 having a threaded sxtension 62 for extending through dome portion 46. Flange 64 secures inner periphery 54 of diaphragm 52 against dome port~on 46 adjacent opening 48 due to tightening nut 68 threadedly received by threaded extension 62. An elongated extended portion 70 extends downward into the reservoir from flange 64 and ~ncludes cavity 72 extending from open first end 60 downward to terminate at cavity end wall 74 adjacent sensor second end 75, as viewed-in FIG. 2. A well kn~w lS ~agnetically actuated electric switching element 76 is secured in cavity 72 by an epoxy filler or the like and i~ ccnnected to a warning device ~not shown) external to the sensor 56 by wires 78, as i9 well kn w n. ~ sealing boot 80 is mounted ad~acent first end 60 to seal the exposed open first end 60. A pla~tic or other suitsble ~ynthetic material is used to form 8 doughnut-shaped float 82 having opening 84 formed therethrough to be s}idably accommodated by elongated extended portion 70. Float 82 includes mag~etic elements 66 imbeddet therein to cooperatingly actuate element 76 when in proximity tberewith so as to indicate a predetermined minimum level -of fluid in the reservoir.
A novel inclusion in sensor 56 is provided comprising a first annular groove 86 formed in the outer annul~r periphery of flange 46 ad~acent first end 60 and , ~ 7 a second annular groove 88 in elongated extended portion to adjacent second cnd 75. Coil spring 90, preferably of spriDg steel, is substantially of uniform diameter aq it extends d~nward from first end 92 accommodated by flange groove 86 and then diminishes in diamet~r at s~cond end 94 to be accommodated by groove 88. The spring is gr~at enough in both diameter and length to permit fsee movement of float 82 substantially along the length of extended portion 70 into ultimate proxim~ty with element 76 so as to cage float 82 from interferring engagement with diaphragm 52 as illustrated by FIGS. 2, 3 and 4.
FIG. 3 graphically illustrates a portion of reservoir housing 14 including the dcwnwardly extended diaphragm 52 to correspontingly displace the fluid 40 leaving the reservoir. Also, float.member 82 is illustrated as correspondingly follcwing the fluid level.
~ FIG. 4, graphically illustrates a portion of reservoir housing 14 including the further downwardly oxtending diaphragm 52. However, 9ince some of the space in re~ervoir housing 14 is occupisd by sensor 56, diaphragm 52 is limited in its abil~ty to displace.all or practically all of the fluid leaving the reservoir. Thus, further lowering of the level of fluit 40 without a corresponding displacement by diaphragm 52 can cause an undesirable vacuum condition to exist in the reservoir. Of course, such condition can be preselectively controlled in view of varying the diaphragm paramRters. However, due to the inclusion of interstice 96 in diaphragm 52 the sealing : effect of the diaphragm can~be removed under such conditLon- as th diaphra~= ateecpts to Fxtend douov ~dly .
ln accordance with the 1uid level. Under these condition~
a potontial vacuum condition can exist in the brake fl~it containing portion of the reservoir wh&reas the air containlng portion remains substantially at atmospheric pressure. Thus a pressur~ differential may exise across diaphragm 52 sufficient to cause interstice 96 to op~n thus permitting air to pass therethrough fro~ the air containing portion of the reservoir to the bxake fluid containing portion.
In the alternative, FIG. 6 illustrates reservoir housing 14a which includes main body portion 26a preferably of cast iron or some other suitable material hav~ng side walls 27a which may be annular os of any suitabls gaometric ~hape. Top end 28a terminates at 30a forming an opening whereas bottom end 32a term~nates at end wall 34a including replenishing port 36a and vent port 38a fos communication oi' fluid 40a with master cylinder 12 not shown.
Cap 42a shown mounted on main portion 26a is preferibly of steel ant is formed with a flange portion 44a and a tome-like postlon 46a. Flange portion 44a i9 provided for slignment with top end 28a of main body portlon 26a as i~ well known.- A vent or port 50a may be provided in cap 42a to communicate the reservoir to atmosphere.
Diaphsagm 52a iB preerably of rubber or somo suitable sesilient synthetic material. The tiaphragm i~
8eslingly secured in the seservoir at outer periphsry 53a between cap 42a and main body portion 26a such as between top end 28a and flange 44a. Diaphragm 52a is convoluted to permit extension thereof downward into main body portion 26a as i5 well known.
~./ , .
_ 9 _ A novel inclusion in diaphragm 52a is provided at slit or interstice 96a provided in a portion of diaphragm 52a inside reservoir 14a in the vicinity of the portion of the diaphragm secured between flange 44a of cap 42a and top end 28a of main body portion 26a. Slit 96a remains closed due to the inharent resilionce of the diaphragm material and is provided to open when a substantial pressure difference exists across diaphragm 52a.
FIG. 7 graphically illustrates a portion of reservoir 14a including fully downwardly extended diaphragm 52a. However, in certain instances such as where the number of permissible convolutions in the diaphragm may be limited due to space limitations or other factors in the reservoir, diaphragm 52a is limited in its ability to di~place all or practically all of the fluid leaving the reservoir. Thus, further lowering of the level of fluid 40a without a corresponding displacement by diaphragm 52a can cause an undesirable vacuum condition to exist in the reservoir. Of course, as stated before, such condition can be preselectively controlled in view of varying the diaphragm parameters. However, due to the inclusion of lnterstice 96a in tiaphragm 52a, the sealing effect of the diaphragm can be removed under such conditions as the diaphragm attempts to extend d~nwardly in accordanca 2S with the fluid level. Unter these conditions 8 potential yacuum condition can exist in the brake fluid containing portion of the reservoir whereas the air containing portion re~ains substantially at atmospheric pressure. Thus, a pressure differential may exist across diaphragm S2a sufficient to cause interstice 96a to open thus permitting air to pass therethrough from the air containing portion of tho reservoir to the braks fluid containing portion.
In operation, the braks fluid level in th~
reservoir is gradually lowered as the system requires additional amounts of fluid due to factors such as wear on thc brake pads or shoes. Diaphrag~ 52 gradually extends townwardly with the fluid level so as to correspondingly displace the volume of fluid lsaving the reservoir.
As the fluid level decreases, float member 82 correspondingly moves downwardly along extended portion 70 of sensor 56, Due to the caged relationship of float member 82 with respect to diaphragm 52, the float member is permitted to move downwardly along extended portion 70 without experiencing interferring engagement with downwardly moving diaphragm 52.
Once the tiaphragm is fully extended downwardly into the reservoir, an undesirable pressure differential across the diaphragm is avoidsd due to the flexibl~ and resil~ nt nature of the diaphragm material to permlt opening of inter9tice 96 thus permitting atmospheric air to pass therethrough into the brake fluid containing portion from the ais containing portion. Onca the pressure differential across the diaphragm diminishes, the resilience of the diaphragm material permits the interstlce to close.
The foregoing has described a novel brake fluid seservois capable of providing a ncn-vacuum creating and non-float interferring relationship between the fluit level, sensor snd diaphragm'therein.
Obviously, other modifications and variations of . . .
the present lnvention are possible in the light of the above teachings. It i9 therefore to be understood that within thc scope of the appended claims the invention may be practiced othen~ise than as specifically describsd,
Claims (7)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A brake fluid reservoir comprising:
a main body portion;
a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetermined minimum level of brake fluid in the reservoir;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air containing portion;
the diaphragm including normally closed interstice means formed therein said interstice means being openable for permitting air in the air containing portion of the reservoir to be drawn into the fluid containing portion under preselected conditions; and said preselected conditions being a difference in pressure between the two sides thereof.
a main body portion;
a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetermined minimum level of brake fluid in the reservoir;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air containing portion;
the diaphragm including normally closed interstice means formed therein said interstice means being openable for permitting air in the air containing portion of the reservoir to be drawn into the fluid containing portion under preselected conditions; and said preselected conditions being a difference in pressure between the two sides thereof.
2. The brake fluid reservoir of claim 1 wherein the brake fluid level sensor means comprises:
an elongated portion; and float means movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of the brake fluid in the reservoir.
an elongated portion; and float means movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of the brake fluid in the reservoir.
3. The brake fluid reservoir of claim 2, and further including:
means mounted on the sensor and concentrically spaced around the elongated portion and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the diaphragm spaced from interfering engagement with the elongated portion and the float means.
means mounted on the sensor and concentrically spaced around the elongated portion and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the diaphragm spaced from interfering engagement with the elongated portion and the float means.
4. In a vehicle brake system of the type including a master cylinder and a brake fluid reservoir in fluid com-munication therewith, an improvement comprising:
a main body portion of the reservoir;
a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetermined minimum level of brake fluid in the reservoir;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air containing portion;
the diaphragm including normally closed interstice means formed therein said interstice means being openable for permitting air in the air containing portion of the reservoir to be drawn into the fluid containing portion under preselected conditions; and said preselected conditions being a difference in pressure between the two sides thereof.
a main body portion of the reservoir;
a cap mounted on the main body;
brake fluid level sensor means mounted on the reservoir and protruding thereinto for indicating a predetermined minimum level of brake fluid in the reservoir;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to a decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air containing portion;
the diaphragm including normally closed interstice means formed therein said interstice means being openable for permitting air in the air containing portion of the reservoir to be drawn into the fluid containing portion under preselected conditions; and said preselected conditions being a difference in pressure between the two sides thereof.
5. The system of claim 4 wherein the brake fluid level sensor means comprises:
an elongated portion; and float means movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of brake fluid in the reservoir.
an elongated portion; and float means movably mounted on the elongated portion and buoyant in the brake fluid responsive for maintaining a constant position with respect to the level of brake fluid in the reservoir.
6. The system of claim 5 , and further including:
means mounted on the sensor and concentrically spaced around the elongated portion-and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the diaphragm spaced from interfering engagement with the elongated portion and the float means.
means mounted on the sensor and concentrically spaced around the elongated portion-and the float means for permitting movement of the float relative to the elongated portion and for maintaining the movement of the diaphragm spaced from interfering engagement with the elongated portion and the float means.
7. A brake fluid reservoir comprising:
a main body portion;
a cap mounted on the main body;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to à decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air con-taining portion;
normally closed interstice means formed in the diaphragm means, said interstice means being openable for permitting air in the air containing portion to pass into the brake fluid containing portion under preselected conditions; and said preselected conditions being a difference in pres-sure between the two sides thereof.
a main body portion;
a cap mounted on the main body;
diaphragm means sealingly secured in the reservoir for corresponding movement in response to à decrease in the level of brake fluid in the reservoir and for separating a brake fluid containing portion of the reservoir from an air con-taining portion;
normally closed interstice means formed in the diaphragm means, said interstice means being openable for permitting air in the air containing portion to pass into the brake fluid containing portion under preselected conditions; and said preselected conditions being a difference in pres-sure between the two sides thereof.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA310,625A CA1058664A (en) | 1975-12-04 | 1978-09-05 | Master cylinder reservoir with vacuum relief diaphragm |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US05/637,643 US4058694A (en) | 1975-12-04 | 1975-12-04 | Master cylinder reservoir with vacuum relief diaphragm and guarded fluid level sensor |
| CA266,160A CA1054188A (en) | 1975-12-04 | 1976-11-19 | Master cylinder reservoir with vacuum relief diaphragm and guarded fluid level sensor |
| CA310,625A CA1058664A (en) | 1975-12-04 | 1978-09-05 | Master cylinder reservoir with vacuum relief diaphragm |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1058664A true CA1058664A (en) | 1979-07-17 |
Family
ID=27164785
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA310,625A Expired CA1058664A (en) | 1975-12-04 | 1978-09-05 | Master cylinder reservoir with vacuum relief diaphragm |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1058664A (en) |
-
1978
- 1978-09-05 CA CA310,625A patent/CA1058664A/en not_active Expired
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