CA1116208A - Hydraulic brake booster and valve member - Google Patents
Hydraulic brake booster and valve memberInfo
- Publication number
- CA1116208A CA1116208A CA321,441A CA321441A CA1116208A CA 1116208 A CA1116208 A CA 1116208A CA 321441 A CA321441 A CA 321441A CA 1116208 A CA1116208 A CA 1116208A
- Authority
- CA
- Canada
- Prior art keywords
- piston
- pressure chamber
- storage chamber
- pressure
- brake booster
- 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
Links
- 239000012530 fluid Substances 0.000 claims abstract description 30
- 238000004891 communication Methods 0.000 claims abstract description 15
- 238000007789 sealing Methods 0.000 description 2
- 238000013022 venting Methods 0.000 description 2
- ZPEZUAAEBBHXBT-WCCKRBBISA-N (2s)-2-amino-3-methylbutanoic acid;2-amino-3-methylbutanoic acid Chemical compound CC(C)C(N)C(O)=O.CC(C)[C@H](N)C(O)=O ZPEZUAAEBBHXBT-WCCKRBBISA-N 0.000 description 1
- 230000002950 deficient Effects 0.000 description 1
- 238000003780 insertion Methods 0.000 description 1
- 230000037431 insertion Effects 0.000 description 1
- PNDPGZBMCMUPRI-UHFFFAOYSA-N iodine Chemical compound II PNDPGZBMCMUPRI-UHFFFAOYSA-N 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000007790 scraping Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
- B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
- B60T13/148—Arrangements for pressure supply
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
- B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
- B60T13/142—Systems with master cylinder
- B60T13/143—Master cylinder mechanically coupled with booster
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60T—VEHICLE BRAKE CONTROL SYSTEMS OR PARTS THEREOF; BRAKE CONTROL SYSTEMS OR PARTS THEREOF, IN GENERAL; ARRANGEMENT OF BRAKING ELEMENTS ON VEHICLES IN GENERAL; PORTABLE DEVICES FOR PREVENTING UNWANTED MOVEMENT OF VEHICLES; VEHICLE MODIFICATIONS TO FACILITATE COOLING OF BRAKES
- B60T13/00—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems
- B60T13/10—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release
- B60T13/12—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid
- B60T13/14—Transmitting braking action from initiating means to ultimate brake actuator with power assistance or drive; Brake systems incorporating such transmitting means, e.g. air-pressure brake systems with fluid assistance, drive, or release the fluid being liquid using accumulators or reservoirs fed by pumps
- B60T13/142—Systems with master cylinder
- B60T13/143—Master cylinder mechanically coupled with booster
- B60T13/144—Pilot valve provided inside booster piston
Abstract
HYDRAULIC BRAKE BOOSTER AND VALVE MEMBER
ABSTRACT OF THE DISCLOSURE
A hydraulic brake booster includes a housing which defines a pressure chamber and a piston within the housing is movable in response to pressurized fluid within the pressure chamber to effectuate a brake application. The piston encloses a storage chamber and forms a passage communicating the storage chamber with the pressure chamber. A valve member is disposed within the passage to control communication between the storage chamber and the pressure chamber. An operator actuator cooperates with a control valve to communicate pressurized fluid to the pressure chamber and a finger is actuated by the operator actuator to engage the valve member, thereby opening communication between the storage chamber and the pressure chamber. The valve member comprises a unitary assembly having a sleeve sealingly engaging the wall of the piston passage, a seat member biased into engagement with a shoulder defined by a stepped bore on the sleeve, and a stem extending through a bore on the seat member.
ABSTRACT OF THE DISCLOSURE
A hydraulic brake booster includes a housing which defines a pressure chamber and a piston within the housing is movable in response to pressurized fluid within the pressure chamber to effectuate a brake application. The piston encloses a storage chamber and forms a passage communicating the storage chamber with the pressure chamber. A valve member is disposed within the passage to control communication between the storage chamber and the pressure chamber. An operator actuator cooperates with a control valve to communicate pressurized fluid to the pressure chamber and a finger is actuated by the operator actuator to engage the valve member, thereby opening communication between the storage chamber and the pressure chamber. The valve member comprises a unitary assembly having a sleeve sealingly engaging the wall of the piston passage, a seat member biased into engagement with a shoulder defined by a stepped bore on the sleeve, and a stem extending through a bore on the seat member.
Description
?J~
The presen~ invention re]ates to a valve m~ber in a hydraulic brake booster.
In Canadian Patent No. 1,0~0,281, issued June 24, 1980, a hydrauLic brake booster includes a piston which is movable in response to pressurized fluid in a pressure chamber to initiate a braking application. In order to conserve space and weight, the piston is hollow to substantially define a storage chamber within the piston.
If the pressure of the pressurized fluid within the lO pressure chamber is insufficient to move the piston during - braking, the storage chamber is communicated to the pressure chamber to assist in moving the piston, thereby providing a power assist to the braking application.
Generally, the storage chamber is communicated to the pressure chamber when a spool valve within the brake booster fails to communicate pressurized fluid to the pressure chamber, either because of an inoperable pressure source or the spool valve becoming wedged in the brake booster housing.
With the pressure source rendered inoperable, the communication of pressurized fluid to the pressure chamber from the storage chamber is re~uired to provide a power assist to braking in order to bring a vehicle to a stop.
Consequently, a reliable valve member ~hich operates to communicate the storage chamber within the piston with the pressure chamber is believed to be an improvement in the state of the art~ Moreover, during assembly it is desirablè to remove only valve members which are not satisfactory without scraping any other parts of the 30 hydraulic brake booster.
The present invention resides in a hydraulic `~ brake booster having a housing defining a pressure chamber, ~ . - ';
a movable piston mounted in the hollsing and clefining a storage chamber within the piston, a contrvl valve mounted in the housing, an operator ac~uator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, and a valve member carried by the piston. In the present invention the valve member includes a unitary assembly for attachment with the piston, the unitary assembly providing for opening and closing communication between the pressure chamber and the storage chamber in response to a pressure differential across the unitary assembly.
In a specific embodiment of the invention, the piston includes a plug which is exposed to the pressure chamber and a passage through the plug receives a valve member. A blind bore in the plug receives an operator actuator and the passage is radially spaced from and offset relative to the blind bore. The valve member comprises a unitary assembly for insertion within the passage, the unitary assembly including a sleeve with a ~0 stepped bore therethrough, a seat member biased against a shoulder formed by the stepped bore and a stem extending through a bore in the seat member.
Also in a specific embodiment of the invention, the operator actuator includes a lever which engages a pin extending through an aperture in the plug. The pin carries a finger which is engageable with the valve member sten. When the pressure of the fluid within the pressure chamber is insufficient to move the piston to a braking position, the lever pivots to urge the finger via the pin into engagement with the stem. As the stem is moved relative to the seat member, the storage chamber is communicated with the pressure chamber to increase the .
, , . : , `, pressure of pressurized fluid within the pressure chamber, thereby providing a power assist to braklng.
It is a primary object of the present invention to provide a unitary assembly which is separate from the piston, but easily connected to the piston for controlling the communication of pressurized fluid from the pressure chamber to the storage chamber and vice versa.
BRIEF DESCRIPTIO~ OF THE DRAWINGS
Figure 1 is a schematic view of a brake system showing a side cross-sectional view of a hydraulic brake booster constructed in accordance with the present invention;
Figure 2 is a side cross-sectional view of the valve member used in the hydraulic brake booster of Figure l; and Figure 3 is a cross-sectional vlew taken along line 3-3 of Figure 1.
D~T~ILED DESCRIPTION
A hydraulic brake booster 10 provides a power assist during braking to increase the force applied to a master cylinder in a vehicle, thereby assisting an operator in stopping the vehicle~ In the hydraulic brake booster of Figure 1, a housing 12 includes a pair of bores 14 and 16 and substantially defines a pressùre chamber 16. A piston 18 disposed in bore 14 is movable - relative to the housing 12 in response to pressurized -~
fluid within the pressure chamber 16. A conventional master cylinder (not shown) connects with the left side of the housing so that movement of the piston 18 causes the master cylinder to communicate brake fluid to a set of wheel cylinders (not shown) to initiate braking of the vehicle.
,, - 3 ~
'` ' : . - ' : .
A control valve 20 disposed within housing ~ore 16 moves relative to the housing to cooperate with an in].et 22, an outlet 24, and a return 26, in order to control communication of pressurized fluid to the p~essure chamber 16. The control valve preferably comprises a spool valve 30 with a passage 32 communicating with the pressure chamber 16. A sleeve 34 carried by the spool valve 30 is movable from a normal position to close the passage 32.
An operator actuator 40 comprises an input rod 42 and a l.ever 44. The lever is pivoted about a pin 46 on the sleeve 34 and about a pin 48 on the piston 18. -A
spring 50 biases the sleeve 34 and pin 46 to one end of the spool valve 30 and a spring 52 biases the pin 48 to one side of a transverse axially elongated aperture 54 on the piston 18. A pair of pins 47 connects the i.nput rod 42 with the lever 44.
In accordance with Canadian Patent No. 1,080,281, the piston 18 forms a storage chamber 60 internally of the piston 18. A diaphragm 62 separates the storage .
chamber 60 from a compressible medium 64 such that pressurized fluid communicated to the storage chamber 60 compresses the medium to maintain the storage chamber 60 under pressure. The piston 18 preferably comprises a stepped cylindrical casing 66 termi.nating in an open end 68 which receives a plug 70. The plug receives the input rod 42 in a blind bore 72 so that it is possible to manually move the piston 18 to a braking position by urging the input rod 42 into the blind bore 72 until , .
~ ~ .
: - 4 -the input rod abuts the boctom of the blind bGre 72, whereupon urther movement of the input rod transMlts movement to the piston 1~.
In accordance with the present invention, a valve Member 71~ is carried in 3 passage ?6 in the plug 70. Viewin~g Figure 2, the val~e member 74 co~prises a unitary assembly for easy ascembly with the pl;lg 70.
The unitary assemblv includes a sleeve 78 with a stepped tDre 50 therethrou~h defining a shoulder 82. A seat member 84 i5 biased into sealing engagement ~ith the shoulder 82 by a spring 86 which is retained within the stepped bore 80 by a ring 88 secured to the sleeve 78. A tapered bore 91 extending through the seat member 84 receives a stem 9û with a head 92~ The stm extends through a polygonal opening 94 in the ring 88 which supports the stem and permits co~munication between the stem and polygonal opening gl,.
When urged to the righ~ in Figure 2, the stem he3d ~2 sealingly engages the seat member 84 and a plura1ity of tabs ~6 Gn the sleeve 7~ oppose the head 92 to define the left pos;tion of the stem head~ ;
The lever 44 is pivotally ~ounted on the pin 48 whict) extends through the ~ransverse axially elongated aperture 54~ The pin 48 carries a finger lûO which is slida~ly mounted in an undercut slot iO2 in the plug 70.
The finger lOû opposes the stem 90, such th3t movement of the 'in~er 100
The presen~ invention re]ates to a valve m~ber in a hydraulic brake booster.
In Canadian Patent No. 1,0~0,281, issued June 24, 1980, a hydrauLic brake booster includes a piston which is movable in response to pressurized fluid in a pressure chamber to initiate a braking application. In order to conserve space and weight, the piston is hollow to substantially define a storage chamber within the piston.
If the pressure of the pressurized fluid within the lO pressure chamber is insufficient to move the piston during - braking, the storage chamber is communicated to the pressure chamber to assist in moving the piston, thereby providing a power assist to the braking application.
Generally, the storage chamber is communicated to the pressure chamber when a spool valve within the brake booster fails to communicate pressurized fluid to the pressure chamber, either because of an inoperable pressure source or the spool valve becoming wedged in the brake booster housing.
With the pressure source rendered inoperable, the communication of pressurized fluid to the pressure chamber from the storage chamber is re~uired to provide a power assist to braking in order to bring a vehicle to a stop.
Consequently, a reliable valve member ~hich operates to communicate the storage chamber within the piston with the pressure chamber is believed to be an improvement in the state of the art~ Moreover, during assembly it is desirablè to remove only valve members which are not satisfactory without scraping any other parts of the 30 hydraulic brake booster.
The present invention resides in a hydraulic `~ brake booster having a housing defining a pressure chamber, ~ . - ';
a movable piston mounted in the hollsing and clefining a storage chamber within the piston, a contrvl valve mounted in the housing, an operator ac~uator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, and a valve member carried by the piston. In the present invention the valve member includes a unitary assembly for attachment with the piston, the unitary assembly providing for opening and closing communication between the pressure chamber and the storage chamber in response to a pressure differential across the unitary assembly.
In a specific embodiment of the invention, the piston includes a plug which is exposed to the pressure chamber and a passage through the plug receives a valve member. A blind bore in the plug receives an operator actuator and the passage is radially spaced from and offset relative to the blind bore. The valve member comprises a unitary assembly for insertion within the passage, the unitary assembly including a sleeve with a ~0 stepped bore therethrough, a seat member biased against a shoulder formed by the stepped bore and a stem extending through a bore in the seat member.
Also in a specific embodiment of the invention, the operator actuator includes a lever which engages a pin extending through an aperture in the plug. The pin carries a finger which is engageable with the valve member sten. When the pressure of the fluid within the pressure chamber is insufficient to move the piston to a braking position, the lever pivots to urge the finger via the pin into engagement with the stem. As the stem is moved relative to the seat member, the storage chamber is communicated with the pressure chamber to increase the .
, , . : , `, pressure of pressurized fluid within the pressure chamber, thereby providing a power assist to braklng.
It is a primary object of the present invention to provide a unitary assembly which is separate from the piston, but easily connected to the piston for controlling the communication of pressurized fluid from the pressure chamber to the storage chamber and vice versa.
BRIEF DESCRIPTIO~ OF THE DRAWINGS
Figure 1 is a schematic view of a brake system showing a side cross-sectional view of a hydraulic brake booster constructed in accordance with the present invention;
Figure 2 is a side cross-sectional view of the valve member used in the hydraulic brake booster of Figure l; and Figure 3 is a cross-sectional vlew taken along line 3-3 of Figure 1.
D~T~ILED DESCRIPTION
A hydraulic brake booster 10 provides a power assist during braking to increase the force applied to a master cylinder in a vehicle, thereby assisting an operator in stopping the vehicle~ In the hydraulic brake booster of Figure 1, a housing 12 includes a pair of bores 14 and 16 and substantially defines a pressùre chamber 16. A piston 18 disposed in bore 14 is movable - relative to the housing 12 in response to pressurized -~
fluid within the pressure chamber 16. A conventional master cylinder (not shown) connects with the left side of the housing so that movement of the piston 18 causes the master cylinder to communicate brake fluid to a set of wheel cylinders (not shown) to initiate braking of the vehicle.
,, - 3 ~
'` ' : . - ' : .
A control valve 20 disposed within housing ~ore 16 moves relative to the housing to cooperate with an in].et 22, an outlet 24, and a return 26, in order to control communication of pressurized fluid to the p~essure chamber 16. The control valve preferably comprises a spool valve 30 with a passage 32 communicating with the pressure chamber 16. A sleeve 34 carried by the spool valve 30 is movable from a normal position to close the passage 32.
An operator actuator 40 comprises an input rod 42 and a l.ever 44. The lever is pivoted about a pin 46 on the sleeve 34 and about a pin 48 on the piston 18. -A
spring 50 biases the sleeve 34 and pin 46 to one end of the spool valve 30 and a spring 52 biases the pin 48 to one side of a transverse axially elongated aperture 54 on the piston 18. A pair of pins 47 connects the i.nput rod 42 with the lever 44.
In accordance with Canadian Patent No. 1,080,281, the piston 18 forms a storage chamber 60 internally of the piston 18. A diaphragm 62 separates the storage .
chamber 60 from a compressible medium 64 such that pressurized fluid communicated to the storage chamber 60 compresses the medium to maintain the storage chamber 60 under pressure. The piston 18 preferably comprises a stepped cylindrical casing 66 termi.nating in an open end 68 which receives a plug 70. The plug receives the input rod 42 in a blind bore 72 so that it is possible to manually move the piston 18 to a braking position by urging the input rod 42 into the blind bore 72 until , .
~ ~ .
: - 4 -the input rod abuts the boctom of the blind bGre 72, whereupon urther movement of the input rod transMlts movement to the piston 1~.
In accordance with the present invention, a valve Member 71~ is carried in 3 passage ?6 in the plug 70. Viewin~g Figure 2, the val~e member 74 co~prises a unitary assembly for easy ascembly with the pl;lg 70.
The unitary assemblv includes a sleeve 78 with a stepped tDre 50 therethrou~h defining a shoulder 82. A seat member 84 i5 biased into sealing engagement ~ith the shoulder 82 by a spring 86 which is retained within the stepped bore 80 by a ring 88 secured to the sleeve 78. A tapered bore 91 extending through the seat member 84 receives a stem 9û with a head 92~ The stm extends through a polygonal opening 94 in the ring 88 which supports the stem and permits co~munication between the stem and polygonal opening gl,.
When urged to the righ~ in Figure 2, the stem he3d ~2 sealingly engages the seat member 84 and a plura1ity of tabs ~6 Gn the sleeve 7~ oppose the head 92 to define the left pos;tion of the stem head~ ;
The lever 44 is pivotally ~ounted on the pin 48 whict) extends through the ~ransverse axially elongated aperture 54~ The pin 48 carries a finger lûO which is slida~ly mounted in an undercut slot iO2 in the plug 70.
The finger lOû opposes the stem 90, such th3t movement of the 'in~er 100
2~ to the left moves the stem 90 to th~ left also.
Turning to Figure 3~ the valve mernber 74 is disposed to the left side of the blind bore 7~ and radially belo~l the centerlina of ~he blind ~ore. rhe plag 70 includes an enlarged d?ameter portion 104 whlch sealingly engages the casing ~6 at the open end 68 and a red~ced diameCer portion 106. The passage 76 ext2nds through the enlargsd diameter por~
ti~n 104 and opens to the pra;sure chamber 16. The reduced dianletzr por-tion 106 forms ~he transvers* axlally elongated apertwre 54 and includes a pocket 108 for receiving the spring 52 which biases the pin 48 and ths finger 100 to~ard one end or the aperture 54. Moreo~er, the reduced
Turning to Figure 3~ the valve mernber 74 is disposed to the left side of the blind bore 7~ and radially belo~l the centerlina of ~he blind ~ore. rhe plag 70 includes an enlarged d?ameter portion 104 whlch sealingly engages the casing ~6 at the open end 68 and a red~ced diameCer portion 106. The passage 76 ext2nds through the enlargsd diameter por~
ti~n 104 and opens to the pra;sure chamber 16. The reduced dianletzr por-tion 106 forms ~he transvers* axlally elongated apertwre 54 and includes a pocket 108 for receiving the spring 52 which biases the pin 48 and ths finger 100 to~ard one end or the aperture 54. Moreo~er, the reduced
3~ dia~,eter portion lOc extends from the bottom of the enl2rged portion 104 and forms the blind hore 72 For receiving tke ?nput rod 42.
_ 5 _ ,~IODE OF OPERATIO~I
The hydraultc brake booster 10 operates 'n a conventional manner to provide a power assist to a braking appliration. For example, ~hen the 5nput rod 42 is moved to the left to initiate braking, the connecti~g pins ~7 cause tha le~er 44 to pivot akout the pin 48 thereby ~ving the eontrol valve 20 to open co,~nunication between ~he inlet 24 and the pressure chamber 16. Pressurized fluid communicated to the pressure chamber 16 imparts a force on the piston 18 to move the piston to the left, thereby actuating the master cylinder to &ommunicate brake fluid to a wheel cylinder, which effectuates a braking application. With pressurized fluid communi-cated to the pressure chamber 16, the storage chamber 60 is charged if the pressure within the pressure chamber is greater than ~he pressure within the storage chamber~ The pressure differential across the valve member 74 causes the stem 90 to be biased against the tabs 96 so tha~
fluid is communicated through the opening ~4, 3 slot 95 in the seat member 84, the clearance between the stem 90 and ~he bore 91 on the seat member, and the clearance between the head 92, and the stepped bore 80 tn order to cvmmunicate the pressurized fluid to the storage chamber 60.
If the pressure in the pressure chamber is less ~han that in the storage cnamber, the head 92 is biased into sealing engagement with the seat member 84 to trap pr~ssurlz~d fluid in the storage chamber 60. If, d~lring braking, the pressure of the pressurized fluid within ~he pres~ure ~hamber is tnsufficient ~o move the pis~on 18, further m~vement of the input rod 42 causes the pivoting lever 44 to move the spsol valve 30 in abutment w~th a stop 31 and to move the stee~e 34 relati~/e to the spool valv~ 30 theraby closing the passage 32~ Continued movement of thé inpu~ rod 42 pivo~s the lever about the pin 46 and urges the pin 4~ and finger 100 to !nove agains~ the spring 52~ The finger 100 engages the stem 90 to move the stem head ~ away frsm the seat member 84, thereby openirlg communication betw~en the storage chamber arld the pressure ehamber. Consequently pressurized fluid is communicat~d from the storage chamber to the pressure chamber to create d force urging the piston to move to the left. There-fore, a power assist is provided during braking by the storage chamber, even though the control valve fails to commllnicate enough pressurized fluid to the pressure chamber.
If the pressurized fluid wirhin the s~oraye chamber 60 is exhausted after a few brake applications without the control valve operating properly, a brake application is still possible, as continued movement of the input rod 42 abuts the latter with the bottom of the blind bore 72, so that movement of the input rod 42 imparts movement to the piston 18 to actuate the master cyl;nder.
When brakTng is ter~inated, the spool valve and sleeve retur~
to their normal position to communicate the pressure chamber w7th the return 26 via passage 37. Consequently, if ~he pressure of the pressurized fluid within the s~orage chamber 60 increases due to he.at or other means to a pressure above a predetermined value, the pressure differential across the stem and seat member causes the stem head and seat menber to move against the spring 86 to open the storage chamber to the pressure chamber in order to relieve the increased pressure in tha storage chamber~
Because the pressure chamber is in communication with the return ~6, the venting of incr~ased pressure to the pressure chamber does not initia~e braking, as the increased pressure communicatsd from the s~or-age chamber to pressure cha0ber is communicated to the return via passage 32 Because the valve member 74 is a unitary assemD1y, the valve .
member can be tested independently of the plug 70 so that defective valve members can be isc7ated before the pluy and attached valve member ars engaged with th~ çasing ~6 to form the piston 18.
Viawing Figure 2, the slseve 78 terminates in a fl3nge 110 which forms a tapered side edge 112. The axial width or the flange is narrower at the junction with the sleeve and the passage 76 is tapered ' at the snd receiving the valve member 74 so that an excessive buildup of pressure within the storage chamber coupled with a ~lfunction of the venting cf the storage chamber causes the flange 110 to deforrn in response to the force of th~ excessive pressure in the storage chamber. The flange deforms to engage the tapered side edge 112 with the tapered passage ~i portion~ thereby rMVing the valve member to the right. This r^overrent urges the stem 90 into engagement with the finger 100 to rnove the stem away from the seat member 84 in order to vent the excessive buildup of pressure within the storage chamber to the pressure chamber.
Although many variations of the present invention are possible by one skilled in the art it is intended that these variations are included wiehin the scope of the appended claims.
~ 8 -
_ 5 _ ,~IODE OF OPERATIO~I
The hydraultc brake booster 10 operates 'n a conventional manner to provide a power assist to a braking appliration. For example, ~hen the 5nput rod 42 is moved to the left to initiate braking, the connecti~g pins ~7 cause tha le~er 44 to pivot akout the pin 48 thereby ~ving the eontrol valve 20 to open co,~nunication between ~he inlet 24 and the pressure chamber 16. Pressurized fluid communicated to the pressure chamber 16 imparts a force on the piston 18 to move the piston to the left, thereby actuating the master cylinder to &ommunicate brake fluid to a wheel cylinder, which effectuates a braking application. With pressurized fluid communi-cated to the pressure chamber 16, the storage chamber 60 is charged if the pressure within the pressure chamber is greater than ~he pressure within the storage chamber~ The pressure differential across the valve member 74 causes the stem 90 to be biased against the tabs 96 so tha~
fluid is communicated through the opening ~4, 3 slot 95 in the seat member 84, the clearance between the stem 90 and ~he bore 91 on the seat member, and the clearance between the head 92, and the stepped bore 80 tn order to cvmmunicate the pressurized fluid to the storage chamber 60.
If the pressure in the pressure chamber is less ~han that in the storage cnamber, the head 92 is biased into sealing engagement with the seat member 84 to trap pr~ssurlz~d fluid in the storage chamber 60. If, d~lring braking, the pressure of the pressurized fluid within ~he pres~ure ~hamber is tnsufficient ~o move the pis~on 18, further m~vement of the input rod 42 causes the pivoting lever 44 to move the spsol valve 30 in abutment w~th a stop 31 and to move the stee~e 34 relati~/e to the spool valv~ 30 theraby closing the passage 32~ Continued movement of thé inpu~ rod 42 pivo~s the lever about the pin 46 and urges the pin 4~ and finger 100 to !nove agains~ the spring 52~ The finger 100 engages the stem 90 to move the stem head ~ away frsm the seat member 84, thereby openirlg communication betw~en the storage chamber arld the pressure ehamber. Consequently pressurized fluid is communicat~d from the storage chamber to the pressure chamber to create d force urging the piston to move to the left. There-fore, a power assist is provided during braking by the storage chamber, even though the control valve fails to commllnicate enough pressurized fluid to the pressure chamber.
If the pressurized fluid wirhin the s~oraye chamber 60 is exhausted after a few brake applications without the control valve operating properly, a brake application is still possible, as continued movement of the input rod 42 abuts the latter with the bottom of the blind bore 72, so that movement of the input rod 42 imparts movement to the piston 18 to actuate the master cyl;nder.
When brakTng is ter~inated, the spool valve and sleeve retur~
to their normal position to communicate the pressure chamber w7th the return 26 via passage 37. Consequently, if ~he pressure of the pressurized fluid within the s~orage chamber 60 increases due to he.at or other means to a pressure above a predetermined value, the pressure differential across the stem and seat member causes the stem head and seat menber to move against the spring 86 to open the storage chamber to the pressure chamber in order to relieve the increased pressure in tha storage chamber~
Because the pressure chamber is in communication with the return ~6, the venting of incr~ased pressure to the pressure chamber does not initia~e braking, as the increased pressure communicatsd from the s~or-age chamber to pressure cha0ber is communicated to the return via passage 32 Because the valve member 74 is a unitary assemD1y, the valve .
member can be tested independently of the plug 70 so that defective valve members can be isc7ated before the pluy and attached valve member ars engaged with th~ çasing ~6 to form the piston 18.
Viawing Figure 2, the slseve 78 terminates in a fl3nge 110 which forms a tapered side edge 112. The axial width or the flange is narrower at the junction with the sleeve and the passage 76 is tapered ' at the snd receiving the valve member 74 so that an excessive buildup of pressure within the storage chamber coupled with a ~lfunction of the venting cf the storage chamber causes the flange 110 to deforrn in response to the force of th~ excessive pressure in the storage chamber. The flange deforms to engage the tapered side edge 112 with the tapered passage ~i portion~ thereby rMVing the valve member to the right. This r^overrent urges the stem 90 into engagement with the finger 100 to rnove the stem away from the seat member 84 in order to vent the excessive buildup of pressure within the storage chamber to the pressure chamber.
Although many variations of the present invention are possible by one skilled in the art it is intended that these variations are included wiehin the scope of the appended claims.
~ 8 -
Claims (18)
1. In a hydraulic brake booster having a housing defining a pressure chamber, a movable piston mounted in the housing and defining a storage chamber within the piston, a control valve mounted in the housing, an operator actuator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, and a valve member carried by the piston, the improvement in which said valve member comprises a unitary assembly for attachment with said piston, said unitary assembly providing for opening and closing communication between the pressure chamber and the storage chamber in response to a pressure differential across said unitary assembly.
2. The hydraulic brake booster of claim 1 in which said unitary assembly includes a sleeve which is disposed in a bore on said piston, a seat member carried by said sleeve and a stem extending through said seat member, said stem and seat member being movable relative to said sleeve when the pressure in the storage chamber is above a predetermined valve to communicate the storage chamber with the pressure chamber, said stem being movable relative to said seat member and said sleeve when the pressure in the pressure chamber is greater than that in the storage chamber to communicate the pressure chamber with the storage chamber, and said stem cooperating with said seat member to close communication between the pressure chamber and the storage chamber when the pressure in the storage chamber is above the pressure in the pressure chamber but less than the predetermined value.
3. The hydraulic brake booster of claim 1 in which said piston includes a plug partially forming the storage chamber, said plug having a blind bore substantially disposed in the center of said plug for receiving said operator actuator, said plug having a passage which is radially disposed from and offset from the center of said plug and said valve member is disposed within said passage,
4. The hydraulic brake booster of claim 2 in which said sleeve supports a ring with an opening and said stem extends through the opening, the opening having a polygonal shape to radially support said stem and permit communication between said ring and stem.
5. The hydraulic brake booster of claim 3 in which said sleeve includes a flange with a tapered side facing said plug, said flange being deformable when excessive pressure builds up in the storage chamber to permit said sleeve to move relative to said plug and to move said stem relative to said sleeve and said seat member to communicate the storage chamber with the pressure chamber in order to vent the excessive pressure buildup in the storage chamber to the pressure chamber.
6. A hydraulic brake booster comprising a housing defining a pressure chamber, a piston mounted in the housing and moving relative to the housing in response to the pressure in the pressure chamber, the piston defining and enclosing a storage chamber, a control valve mounted in the housing, an operator actuator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, and a valve member including a unitary assembly for attachment with the piston, said unitary assembly providing for opening and closing communication between the pressure chamber and the storage chamber in response to a pressure differential across the unitary assembly, a finger carried by said piston, said operator actuator cooperating with said finger to urge said finger into engagement with said valve member to control the communication of pressurized fluid from the storage chamber to the pressure chamber.
7. The hydraulic brake booster of claim 6 in which said operator actuator includes a lever which pivots relative to said piston in a first position and pivots relative to said control valve in a second position, said lever urging said finger into engagement with said valve member when said lever pivots in the second position.
8. The hydraulic brake booster of claim 7 in which said piston includes an enlarged diameter portion and a reduced diameter portion and a passage extending through the enlarged diameter portion communicates the storage chamber with the pressure chamber, said valve member being disposed in said passage and said finger being movably supported by said lever adjacent the reduced diameter portion.
9. The hydraulic brake booster of claim 7 in which said lever includes a pin and said piston includes an aperture for receiving said pin, said finger being supported on said pin.
10. The hydraulic brake booster of claim 9 in which the aperture includes an axial dimension which is greater than the radial dimension of the aperture to permit said pin to move axially in the aperture, said pin being resiliently biased axially to one side of the aperture.
11. The hydraulic brake booster of claim 8 in which the passage terminates in a slot and said finger is movably disposed in the slot.
12. A hydraulic brake booster comprising a housing defining a pressure chamber, a piston disposed within the housing and moving relative to the housing in response to pressure communicated to the pressure chamber the piston defining and enclosing a storage chamber, a control valve mounted in the housing, an operator actuator imparting movement to the piston when the pressure within the pressure chamber is below a predetermined value, said actuator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, a passage through the piston communicates the storage chamber with the pressure chamber and a valve member is disposed in the passage, said valve member comprising a sleeve sealingly engaging the wall of the passage, said sleeve having a stepped bore therethrough defining a shoulder, a seat member resiliently biased into engagement with the shoulder, and a stem extending through a bore in the seat member, said stem normally engaging the seat member to close the seat member bore and said seat member normally engaging the shoulder to close the sleeve stepped bore to normally close communication between the storage chamber and the pressure chamber.
13. The hydraulic brake booster of claim 1 wherein said unitary assembly comprises a sleeve with a stepped bore therethrough defining a shoulder, a seat member resiliently biased into engagement with the shoulder to close the stepped bore, and a stem extending through a bore on the seat member, said stem including a head engageable with the seat member to close the bore, said stem being movable relative to the seat member to open the bore, and said seat member being movable relative to the sleeve to open the stepped bore.
14. The valve member of claim 13 in which said sleeve includes at least one tab extending into the stepped bore to limit the axial movement of the stem head between the one tab and the seat member.
15. The valve member of claim 13 in which said sleeve supports a ring at one end of the stepped bore, said ring forming a stop to urge a spring toward the shoulder to bias the seat member against the shoulder and supporting the stem within the stepped bore.
16. A hydraulic brake booster having a housing defining a pressure chamber, a movable piston mounted in the housing and defining a storage chamber within the piston, a control valve mounted in the housing, an operator actuator cooperating with the control valve to communicate pressurized fluid to the pressure chamber, and a valve member in a unitary assembly attached to the piston, said valve member being deformable when the pressure within the storage chamber is above a predetermined value and said valve member cooperates with a stem to open communication between the pressure chamber and the storage chamber when said valve member is deformed.
17. The hydraulic brake booster of claim 16 in which said valve member includes a flange having a tapered side edge, said flange being deformable in response to pressure in the storage chamber above a predetermined value.
18. The hydraulic brake booster of claim 17 in which said valve member is disposed in a passage in the piston and said passage leads to a tapered portion which opposes the tapered side edge on the valve member flange.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US88582578A | 1978-03-13 | 1978-03-13 | |
| US885,825 | 1978-03-13 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1116208A true CA1116208A (en) | 1982-01-12 |
Family
ID=25387777
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA321,441A Expired CA1116208A (en) | 1978-03-13 | 1979-02-14 | Hydraulic brake booster and valve member |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS5855022B2 (en) |
| AR (1) | AR216718A1 (en) |
| AU (1) | AU518545B2 (en) |
| CA (1) | CA1116208A (en) |
| DE (1) | DE2909734A1 (en) |
| FR (1) | FR2419851A1 (en) |
| GB (1) | GB2016102B (en) |
| IT (1) | IT1110623B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3041247A1 (en) * | 1980-11-03 | 1982-06-09 | Alfred Teves Gmbh, 6000 Frankfurt | HYDRAULIC POWER AMPLIFIER |
| US6732518B1 (en) * | 2002-12-02 | 2004-05-11 | Robert Bosch Corporation | Hydraulic brake booster |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3695731A (en) * | 1968-02-01 | 1972-10-03 | Michael John England | Vehicle braking system |
| CA1080281A (en) * | 1976-09-13 | 1980-06-24 | Arthur K. Brown | Hydraulic brake booster reserve system |
-
1979
- 1979-02-14 CA CA321,441A patent/CA1116208A/en not_active Expired
- 1979-02-28 GB GB7907111A patent/GB2016102B/en not_active Expired
- 1979-03-05 AU AU44805/79A patent/AU518545B2/en not_active Ceased
- 1979-03-09 IT IT20869/79A patent/IT1110623B/en active
- 1979-03-13 DE DE19792909734 patent/DE2909734A1/en not_active Withdrawn
- 1979-03-13 FR FR7906329A patent/FR2419851A1/en active Granted
- 1979-03-13 JP JP54028338A patent/JPS5855022B2/en not_active Expired
- 1979-03-13 AR AR275792A patent/AR216718A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| DE2909734A1 (en) | 1979-09-20 |
| JPS5855022B2 (en) | 1983-12-07 |
| FR2419851A1 (en) | 1979-10-12 |
| GB2016102B (en) | 1982-06-09 |
| GB2016102A (en) | 1979-09-19 |
| FR2419851B1 (en) | 1984-10-19 |
| IT7920869A0 (en) | 1979-03-09 |
| AU518545B2 (en) | 1981-10-08 |
| AR216718A1 (en) | 1980-01-15 |
| IT1110623B (en) | 1985-12-23 |
| AU4480579A (en) | 1979-09-20 |
| JPS54126878A (en) | 1979-10-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |