CA1120974A - Pressure limiter for hydraulic brake booster - Google Patents
Pressure limiter for hydraulic brake boosterInfo
- Publication number
- CA1120974A CA1120974A CA000334300A CA334300A CA1120974A CA 1120974 A CA1120974 A CA 1120974A CA 000334300 A CA000334300 A CA 000334300A CA 334300 A CA334300 A CA 334300A CA 1120974 A CA1120974 A CA 1120974A
- Authority
- CA
- Canada
- Prior art keywords
- pressure chamber
- pressurized fluid
- valve assembly
- pressure
- control valve
- 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
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
- B60T13/16—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 pumps directly, i.e. without interposition of accumulators or reservoirs
- B60T13/161—Systems with master cylinder
- B60T13/162—Master cylinder mechanically coupled with booster
Landscapes
- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Braking Systems And Boosters (AREA)
- Braking Arrangements (AREA)
Abstract
PRESSURE LIMITED FOR HYDRAULIC BRAKE BOOSTER
ABSTRACT OF THE DISCLOSURE
The present invention relates to an improvement in a hydraulic brake booster, and in particular, covers a structure which provides a pressure limiter for the hydraulic brake booster. The booster comprises a housing which defines a pressure chamber and supports a control valve and a piston. During braking the control valve cooperates with an actuator to move relative to the housing so as to communicate pressurized fluid to the pressure chamber and the piston is movable in response to the pressurized fluid within the pressure chamber to effectuate braking.
In order to limit the level of pressure of pressurized fluid communi-cated to the pressure chamber a ring is disposed within the housing in cooperation with the control valve. The ring cooperates with the control valve to define a differential area which is exposed to pres-surized fluid to generate a force opposing movement of the control valve so that communication of pressurized Fluid to the pressure chamber is limited. In a preferred embodiment the ring is integrally formed with a sleeve to form a differential area responsive to the pressurized fluid communicated to the pressure chamber and the sleeve cooperates with a resilient member to bias the control valve to a non-braking position.
ABSTRACT OF THE DISCLOSURE
The present invention relates to an improvement in a hydraulic brake booster, and in particular, covers a structure which provides a pressure limiter for the hydraulic brake booster. The booster comprises a housing which defines a pressure chamber and supports a control valve and a piston. During braking the control valve cooperates with an actuator to move relative to the housing so as to communicate pressurized fluid to the pressure chamber and the piston is movable in response to the pressurized fluid within the pressure chamber to effectuate braking.
In order to limit the level of pressure of pressurized fluid communi-cated to the pressure chamber a ring is disposed within the housing in cooperation with the control valve. The ring cooperates with the control valve to define a differential area which is exposed to pres-surized fluid to generate a force opposing movement of the control valve so that communication of pressurized Fluid to the pressure chamber is limited. In a preferred embodiment the ring is integrally formed with a sleeve to form a differential area responsive to the pressurized fluid communicated to the pressure chamber and the sleeve cooperates with a resilient member to bias the control valve to a non-braking position.
Description
The presen-t invention relates to a hydraulic brake booster, and more particularly, to a pressure limiter for a hydraulic brake booster.
As evidenced by U.~. Patents 3,72~,332 and 3,728,9~2, it is known that the movement of a spool valve in a hydraulic brake booster can be limited so as to provide a pressure limiter for the pressurized fluid within a pressure chamber.
The control valve is movable within a bore in the housing to open an inlet port to the pressure chamber while at the same time closing an outlet port so that pressurized fluid communicated to the pressure chamber is increased. If the level of pressure within the pressure chamber reaches a predetermined value, the pressure limiter is activated to prohibit further increases in the pressure level.
The present inventi.on relates to an improvernent in a pressure limiter for a hydraulic brake booster. The brake booster includes a housing ~hich movably suppor-ts..a control valve and substantially defines a pressure chamber.
An actuator resiliently cooperates wi-th the control valve to impart movement to the latter upon operator demand so that pressurized fluid is communicated to the pressure chamber.
A pressure responsive elemen-t moves in response to the pressurized fluid within the pressure chamber to effectuate brakiny. The control valve includes a valve assembly having a firs-t portion and a second portion which are exposed to the pressure of the pressurized fluid within khe pressure chamber.
The first portion and the second portion define a differential area wh:ich is responsive to the pressure oE the pressurized fluid to oppose movement of the valve assembly as the pressure level of pressurized fluid reaches a predetermined value.
~ n a specific embodiment of the invention the valve assembly includes a rin~ which cooperates with the control valve to define a differential area in communication with the pressurized ~luid within the pressure chamber. More specifically, the control valve and ring are movably disposed within a stepped bore in the housing with the control valve being positioned in a small diameter portion and the ring being positioned in a large diameter portion. The control valve is engageable with the ring so that the pressure acting against the ring and con-trol valve generates a larger force in one direction -than the pressure acting agains-t the control valve generates in the other direc-tion. As a result, increasing levels of pressure within the pressure chamber create larger ~orces urging the ring and control valve to move in one direction until the force in the one direction is substantially equal to and opposite the force applied by the actuator coupled with the other direction force. With the forces on the control valve being sub-stantially equal and opposite~ the control valve is fixed axially rela-tive to the housing so as to prevent further increases in communication of pressurized fluid to the pressure chamber, therefore, a maximum pressure level is set.
Preferably, the ring is integrally formed with a sleeve and a resilient member cooperates with the sleeve to bias the ring into 1~ engagem~nt with the control valve. Moreover, the ring is exposed to pressurized fluid on both sides thereof, until the control valve is ~ved to a position to close an outlet port at which time the ring is exposed to pressurized fluid on one side so as to bias the ring toward the control valve.
An alternative embodiment provides a sealing ring which is dis-posed between the sleeve and control valve but separate therefrom.
It is an object of the present invention to provide a pressure or travel limiter in a hydraulic brake booster which is simple to inte-grate into a prior art booster.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic view of a hydraulic braking system showing a hydraulic brake booster in cross section and constructed in accordance with the present invention;
Figure 2 is an enlarged view of the encircled portion of Figure 1; and Figure 3 is an enlarged view similar to Figure 2, but showing an alternative embodiment.
DETAILED DESCRIPTION
-The hydraulic brake system of Figure 1 includes a hydraulic brake booster 10 which is in communicalion with a pressure source 12, such as a 9~74 power steering pump, via conduit 14 whi1e a conduit 16 communicates the booster lO with a reservoir in the pressure source 12. The system also includes a steering gear 18 communicating with the booster lO via conduit 20 and with the reservo;r of the pressure source 12 via cond~lit 22.
The hydraulic brake booster lO includes a housing 24 which sub-stantially defines a pressure chamber 26, while a pair of bores at 28 and 30 movably support a control valve 32 and piston 34, respectively.
Extending into the housing 24 is an input rod 36 which cooperates with a lever 38 to impart movement to the control valve 32, via a cap 37 and a spring 39. The rod 36 atso opposes the piston 34 to impart manual travel to the piston should the hydraulic system fail to provide a power assist as explained hereinafter. The piston 34 defines and encloses a storage chamber 40 and a link 42 extending from the piston 34, is coupled to a master cylinder (not shown)~
A resil;ent member or spring 46 is carried by the input rod 36 to resiliently pivot lever 38 about pin 48 so as to impart travel ~o the control valve 32. During braking an inlet port 50 communicates with a passage S2 in the control valve as the latter is moved to the left to communicate pressurized fluid to the pressure chamber 26. The piston 34 is movable in response to the pressurized fluid within the pressure chamber 26 to actuate the master cylinder, thereby effectuating braking with a power assist from the pressurized fluid within the pressure chamber 26.
In accordance with the invention, the bore 28 is stepped to movably receive a valve assembly 31 comprising the control valve 32 and a ring 569 the control valve 32 being substantially disposed within a small diameter portion 54 and the ring 56 being slidably disposed withtn a large diameter portion 58. Turning to Flgure 2, the ring 56 is integrally formed with a sleeve 60 and a spring 62 biases the sleeve 60 and ring 56 toward the control valve 32. The sleeve 60 is '7~
disposed within a bore 61 on the control valve 32 and a flange 63 abuts a shoulder 67 and opposes the spring 62. The left end of the control valve 32 extends into the large diameter portion 58 and forms a cavity 64 therewith. The cavity communicates with the return conduit 16 when the con~rol valve is in its rest position to expose the right side of the ring to pressurized fluid. The control valve 32 and ring 56 cooperate to define a differential area which is related to the difference in diameters between the portions 54 and 58.
When the control valve 32 is initially moved to the left away from its rest position9 pressuri7ed fluid is communicated to the pressure chamber 26 via passage 52~ The same pressurized fluid is communicated to the left end of the control valve 32 via an opening 65 on the sleeve 60 to react against the ring 56. A land 66 on the control valve 32 cooperates with the small diameter pvrtion 54 to close communication between the passage 52 and the return conduit 16 so that the cavity 64 is vented to the return. As a result, the same pressure applied across the ring 56 in the larger diameter portion 58 will create a larger force than that pressure applied across the control valve in the smaller diameter portion. With the ring 56 in engagement with the control valve the resulting force on the control valve will be sufficient to oppose furtker movement of the con-trol valve to the left in response to movement of the input rod 36 when the pressure of the pressurized fluid reaches a predetermined value. Con-sequently, further opening of the inlet port 50 will be prevented.
By varying the spring constants of the springs 46, 39 and 62 and the diameters of portion 54 and 58, it is possible to set a maximum pressure level for the pressure chamber to prevent pressure increases above the maximum predetermined pressure level.
Turning to Flgure 3, the ring 56 is separate from the sleeve 60 and the latter is provided with a radially outwardly extending flanse 68 to trap the ring between the left end of the control valve 32 and the ~2~'7~
flange 68. Although not shown, it is possible to use an 0-Ring for the ring 56.
In both embodiments, the same pressurized fluid, which is com-municated to the pressure chamber, is also utilized to react against a differential area between the ring and the control valve in order to offset further movement of the control valve when the pressurized fluid reaches a predetermined valueO
Although the ring 56 cooperates with the control valve to limit ~he travel of the latter, the ring 56 is pressure responsive so that the differential area defined between the ring 56 and the control valve 32 acts to limit the pressure level within the pressure chamber 26.
In addition it is possible to provide a skirt (not shown~ on the cap 37 which would be engageable with the wall 70 of the housing after a predetermined travel for the cap so that the differential area between the ring and control valve ~ould be a function of the spring constants for springs 62 and 39. As a result the differential area could be set independently of the spring 46~
Moreover3 if the maximum pressure level is reached in the pres-sure chamber so that the differential acts to prevent further opening of the inlet port 56 and the piston 34 fails to move due to frictlon or sticking, the input rod 36 is capable of further movement to contract the spring 46 and impart manual movement to the piston 34.
The appended claims are intended to cover not only the embodiments illustrated in the drawings~ but also all modifications and~or variations which are feasible by one skilled in the art.
As evidenced by U.~. Patents 3,72~,332 and 3,728,9~2, it is known that the movement of a spool valve in a hydraulic brake booster can be limited so as to provide a pressure limiter for the pressurized fluid within a pressure chamber.
The control valve is movable within a bore in the housing to open an inlet port to the pressure chamber while at the same time closing an outlet port so that pressurized fluid communicated to the pressure chamber is increased. If the level of pressure within the pressure chamber reaches a predetermined value, the pressure limiter is activated to prohibit further increases in the pressure level.
The present inventi.on relates to an improvernent in a pressure limiter for a hydraulic brake booster. The brake booster includes a housing ~hich movably suppor-ts..a control valve and substantially defines a pressure chamber.
An actuator resiliently cooperates wi-th the control valve to impart movement to the latter upon operator demand so that pressurized fluid is communicated to the pressure chamber.
A pressure responsive elemen-t moves in response to the pressurized fluid within the pressure chamber to effectuate brakiny. The control valve includes a valve assembly having a firs-t portion and a second portion which are exposed to the pressure of the pressurized fluid within khe pressure chamber.
The first portion and the second portion define a differential area wh:ich is responsive to the pressure oE the pressurized fluid to oppose movement of the valve assembly as the pressure level of pressurized fluid reaches a predetermined value.
~ n a specific embodiment of the invention the valve assembly includes a rin~ which cooperates with the control valve to define a differential area in communication with the pressurized ~luid within the pressure chamber. More specifically, the control valve and ring are movably disposed within a stepped bore in the housing with the control valve being positioned in a small diameter portion and the ring being positioned in a large diameter portion. The control valve is engageable with the ring so that the pressure acting against the ring and con-trol valve generates a larger force in one direction -than the pressure acting agains-t the control valve generates in the other direc-tion. As a result, increasing levels of pressure within the pressure chamber create larger ~orces urging the ring and control valve to move in one direction until the force in the one direction is substantially equal to and opposite the force applied by the actuator coupled with the other direction force. With the forces on the control valve being sub-stantially equal and opposite~ the control valve is fixed axially rela-tive to the housing so as to prevent further increases in communication of pressurized fluid to the pressure chamber, therefore, a maximum pressure level is set.
Preferably, the ring is integrally formed with a sleeve and a resilient member cooperates with the sleeve to bias the ring into 1~ engagem~nt with the control valve. Moreover, the ring is exposed to pressurized fluid on both sides thereof, until the control valve is ~ved to a position to close an outlet port at which time the ring is exposed to pressurized fluid on one side so as to bias the ring toward the control valve.
An alternative embodiment provides a sealing ring which is dis-posed between the sleeve and control valve but separate therefrom.
It is an object of the present invention to provide a pressure or travel limiter in a hydraulic brake booster which is simple to inte-grate into a prior art booster.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 is a schematic view of a hydraulic braking system showing a hydraulic brake booster in cross section and constructed in accordance with the present invention;
Figure 2 is an enlarged view of the encircled portion of Figure 1; and Figure 3 is an enlarged view similar to Figure 2, but showing an alternative embodiment.
DETAILED DESCRIPTION
-The hydraulic brake system of Figure 1 includes a hydraulic brake booster 10 which is in communicalion with a pressure source 12, such as a 9~74 power steering pump, via conduit 14 whi1e a conduit 16 communicates the booster lO with a reservoir in the pressure source 12. The system also includes a steering gear 18 communicating with the booster lO via conduit 20 and with the reservo;r of the pressure source 12 via cond~lit 22.
The hydraulic brake booster lO includes a housing 24 which sub-stantially defines a pressure chamber 26, while a pair of bores at 28 and 30 movably support a control valve 32 and piston 34, respectively.
Extending into the housing 24 is an input rod 36 which cooperates with a lever 38 to impart movement to the control valve 32, via a cap 37 and a spring 39. The rod 36 atso opposes the piston 34 to impart manual travel to the piston should the hydraulic system fail to provide a power assist as explained hereinafter. The piston 34 defines and encloses a storage chamber 40 and a link 42 extending from the piston 34, is coupled to a master cylinder (not shown)~
A resil;ent member or spring 46 is carried by the input rod 36 to resiliently pivot lever 38 about pin 48 so as to impart travel ~o the control valve 32. During braking an inlet port 50 communicates with a passage S2 in the control valve as the latter is moved to the left to communicate pressurized fluid to the pressure chamber 26. The piston 34 is movable in response to the pressurized fluid within the pressure chamber 26 to actuate the master cylinder, thereby effectuating braking with a power assist from the pressurized fluid within the pressure chamber 26.
In accordance with the invention, the bore 28 is stepped to movably receive a valve assembly 31 comprising the control valve 32 and a ring 569 the control valve 32 being substantially disposed within a small diameter portion 54 and the ring 56 being slidably disposed withtn a large diameter portion 58. Turning to Flgure 2, the ring 56 is integrally formed with a sleeve 60 and a spring 62 biases the sleeve 60 and ring 56 toward the control valve 32. The sleeve 60 is '7~
disposed within a bore 61 on the control valve 32 and a flange 63 abuts a shoulder 67 and opposes the spring 62. The left end of the control valve 32 extends into the large diameter portion 58 and forms a cavity 64 therewith. The cavity communicates with the return conduit 16 when the con~rol valve is in its rest position to expose the right side of the ring to pressurized fluid. The control valve 32 and ring 56 cooperate to define a differential area which is related to the difference in diameters between the portions 54 and 58.
When the control valve 32 is initially moved to the left away from its rest position9 pressuri7ed fluid is communicated to the pressure chamber 26 via passage 52~ The same pressurized fluid is communicated to the left end of the control valve 32 via an opening 65 on the sleeve 60 to react against the ring 56. A land 66 on the control valve 32 cooperates with the small diameter pvrtion 54 to close communication between the passage 52 and the return conduit 16 so that the cavity 64 is vented to the return. As a result, the same pressure applied across the ring 56 in the larger diameter portion 58 will create a larger force than that pressure applied across the control valve in the smaller diameter portion. With the ring 56 in engagement with the control valve the resulting force on the control valve will be sufficient to oppose furtker movement of the con-trol valve to the left in response to movement of the input rod 36 when the pressure of the pressurized fluid reaches a predetermined value. Con-sequently, further opening of the inlet port 50 will be prevented.
By varying the spring constants of the springs 46, 39 and 62 and the diameters of portion 54 and 58, it is possible to set a maximum pressure level for the pressure chamber to prevent pressure increases above the maximum predetermined pressure level.
Turning to Flgure 3, the ring 56 is separate from the sleeve 60 and the latter is provided with a radially outwardly extending flanse 68 to trap the ring between the left end of the control valve 32 and the ~2~'7~
flange 68. Although not shown, it is possible to use an 0-Ring for the ring 56.
In both embodiments, the same pressurized fluid, which is com-municated to the pressure chamber, is also utilized to react against a differential area between the ring and the control valve in order to offset further movement of the control valve when the pressurized fluid reaches a predetermined valueO
Although the ring 56 cooperates with the control valve to limit ~he travel of the latter, the ring 56 is pressure responsive so that the differential area defined between the ring 56 and the control valve 32 acts to limit the pressure level within the pressure chamber 26.
In addition it is possible to provide a skirt (not shown~ on the cap 37 which would be engageable with the wall 70 of the housing after a predetermined travel for the cap so that the differential area between the ring and control valve ~ould be a function of the spring constants for springs 62 and 39. As a result the differential area could be set independently of the spring 46~
Moreover3 if the maximum pressure level is reached in the pres-sure chamber so that the differential acts to prevent further opening of the inlet port 56 and the piston 34 fails to move due to frictlon or sticking, the input rod 36 is capable of further movement to contract the spring 46 and impart manual movement to the piston 34.
The appended claims are intended to cover not only the embodiments illustrated in the drawings~ but also all modifications and~or variations which are feasible by one skilled in the art.
Claims (11)
1. In a hydraulic brake booster having a housing defining a pressure chamber, a valve assembly cooperating with the housing to communicate pressurized fluid to the pressure chamber, means responsive to the pressurized fluid within the pressure chamber to effectuate braking and an actuator cooperating with the valve assembly to move the valve assembly relative to the housing, the improvement wherein the valve assembly includes a first portion and a second portion which are exposed to the pressure of the pressurized fluid within the pressure chamber, said first portion and said second portion defining a differential area which is responsive to the pressure of the pressurized fluid to oppose movement of the valve assembly as the pressure level of pressurized fluid reaches a predetermined value.
2. The hydraulic brake booster of claim 1, in which said second portion of the valve assembly is larger in diameter than said first portion of the valve assembly, and said second portion is disposed on the valve assembly opposite the actuator.
3. The hydraulic brake booster of claim 2 in which said first portion of the valve assembly comprises a control valve and said second portion of the valve assembly comprises a ring which is separate from the control valve.
4. In a hydraulic brake booster having a housing defining a pressure chamber, a control valve cooperating with the housing to com-municate pressurized fluid to the pressure chamber, a piston movable relative to the housing in response to the pressurized fluid within the pressure chamber in order to effectuate braking and an actuator cooperating with the control valve to move the latter to a position communicating pressurized fluid to the pressure chamber, the improvement wherein said control valve has a first portion exposed to the pressurized fluid and a ring cooperates with the control valve to limit communication of pressurized fluid to the pressure chamber, said ring being responsive to the pressurized fluid within the housing to oppose movement of the control valve as the pressure level of pressurized fluid reaches a pre-determined value, said first portion and said ring defining a differential area of exposure to said pressurized fluid.
5. The hydraulic brake booster of claim 4 in which said ring is normally exposed to pressurized fluid on both sides thereof and the control valve is movable to vent the pressurized fluid on one side of said ring.
6. The hydraulic brake booster of claim 4 in which said ring is resiliently biased toward the control valve.
7. The hydraulic brake booster of claim 1, wherein said second portion is a ring cooperating with the valve assembly to limit the movement of the latter, said ring being responsive to the pressurized fluid to oppose movement of the valve assembly when the pressurized fluid reaches the predetermined value.
8. The hydraulic brake booster of claim 7 in which the valve assembly is movably disposed within a stepped bore which defines a shoulder, and a resilient member biases said ring toward said shoulder.
9. In a hydraulic brake booster having a housing defining a pressure chamber, a valve assembly cooperating with the housing to communicate pressurized fluid to the pressure chamber, means responsive to the pressurized fluid within the pressure chamber to effectuate braking an actuator cooperating with the valve assembly to move the valve assembly relative to the housing, resilient input means for moving said actuator and said valve assembly responsive to a brake application, the improvement wherein the valve assembly includes a first portion and a second portion both of which are exposed to the pressure of the pressurized fluid within the pressure chamber, said first portion and said second portion defining a differential area which is responsive to the pressure of the pressurized fluid to create a force opposing movement of the valve assembly by said resilient input means, said force causing said resilient input means to yield when the pressure of said pressurized fluid within said pressure chamber is substantially equal to a predetermined value so that said valve assembly remains substantially fixed.
10. In a hydraulic brake booster comprising a housing defining a pressure chamber and a pair of bores therein, each of said bores opening into said pressure chamber at one of their respective ends, the other end of one of said bores opening into a chamber which communicates with the atmosphere;
a pressure responsive piston slidably received in said one bore, said piston being responsive to pressure in said pressure chamber to slide toward said atmospheric chamber, resilient means for urging said piston toward said pressure chamber; an input rod slidably carried by said housing and engageable with said piston to move the latter toward said atmospheric chamber; a pressure responsive control valve assembly slidably received in the other of said bores; said housing defining an inlet, an outlet, and a vent, all of which communicate with said other bore; said other bore being stepped to provide a small diameter bore portion opening into said pressure chamber, and a large diameter bore portion remote from said pressure chamber, said control valve assembly including a valve member slidably received in said small diameter bore portion and shiftable between
10. In a hydraulic brake booster comprising a housing defining a pressure chamber and a pair of bores therein, each of said bores opening into said pressure chamber at one of their respective ends, the other end of one of said bores opening into a chamber which communicates with the atmosphere;
a pressure responsive piston slidably received in said one bore, said piston being responsive to pressure in said pressure chamber to slide toward said atmospheric chamber, resilient means for urging said piston toward said pressure chamber; an input rod slidably carried by said housing and engageable with said piston to move the latter toward said atmospheric chamber; a pressure responsive control valve assembly slidably received in the other of said bores; said housing defining an inlet, an outlet, and a vent, all of which communicate with said other bore; said other bore being stepped to provide a small diameter bore portion opening into said pressure chamber, and a large diameter bore portion remote from said pressure chamber, said control valve assembly including a valve member slidably received in said small diameter bore portion and shiftable between
Claim 10 cont'd...
between a first position in which said valve member communicates said inlet with said outlet and closes communication between said inlet and said pressure chamber and a second position in which said valve member closes communication between said inlet and said outlet and opens communication from said inlet to said pressure chamber, said valve member including a portion extending into said pressure chamber and engaging an abutment defined by said housing to define said first position, first resilient means for urging said valve member to said first position; said control valve assembly further including a ring member slidably received in said large diameter bore portion and engaging said valve member, said ring member cooperating with said valve member and with said large diameter bore portion to define an annular chamber communicating with said vent, said ring member cooperating with said large diameter bore portion to define one chamber communicating with said pressure chamber via a passage in said valve member; said control valve assembly thereby defining three differential areas, the first of said areas being defined by said valve member, the second of said areas being defined by said ring member, and the third area being defined by the difference between said first and said second areas, said third area being exposed to the pressure in said annular chamber; a cap member and a second resilient member both slidably carried on the extending portion of said control valve in said pressure chamber; a lever pivotally carried by said piston and pivotally engaging said cap member, said lever being engaged by said input rod to pivot responsive to movement of said input rod toward said piston, pivotal movement of said lever moving said valve assembly via said cap member and said second resilient member ?oward said second position to communicate pressurized fluid from said inlet to said pressure chamber, said valve assembly being movable toward said second position until the combination of force from said first resilient means plus force provided by the pressure differential between said one chamber and said annular chamber which acts on said third differential area balances the force provided by said second resilient member, further pivotal movement of said lever shifting said cap member along said extending portion of said valve member and contracting said second resilient member so that said control valve assembly remains substantially fixed relative to said housing.
between a first position in which said valve member communicates said inlet with said outlet and closes communication between said inlet and said pressure chamber and a second position in which said valve member closes communication between said inlet and said outlet and opens communication from said inlet to said pressure chamber, said valve member including a portion extending into said pressure chamber and engaging an abutment defined by said housing to define said first position, first resilient means for urging said valve member to said first position; said control valve assembly further including a ring member slidably received in said large diameter bore portion and engaging said valve member, said ring member cooperating with said valve member and with said large diameter bore portion to define an annular chamber communicating with said vent, said ring member cooperating with said large diameter bore portion to define one chamber communicating with said pressure chamber via a passage in said valve member; said control valve assembly thereby defining three differential areas, the first of said areas being defined by said valve member, the second of said areas being defined by said ring member, and the third area being defined by the difference between said first and said second areas, said third area being exposed to the pressure in said annular chamber; a cap member and a second resilient member both slidably carried on the extending portion of said control valve in said pressure chamber; a lever pivotally carried by said piston and pivotally engaging said cap member, said lever being engaged by said input rod to pivot responsive to movement of said input rod toward said piston, pivotal movement of said lever moving said valve assembly via said cap member and said second resilient member ?oward said second position to communicate pressurized fluid from said inlet to said pressure chamber, said valve assembly being movable toward said second position until the combination of force from said first resilient means plus force provided by the pressure differential between said one chamber and said annular chamber which acts on said third differential area balances the force provided by said second resilient member, further pivotal movement of said lever shifting said cap member along said extending portion of said valve member and contracting said second resilient member so that said control valve assembly remains substantially fixed relative to said housing.
11. In a hydraulic brake booster having a housing defining a pressure chamber, an inlet and an outlet for com-municating pressurized fluid through the housing, valve means movable within the housing to communicate the pressurized fluid to the pressure chamber, an actuator cooperating with the valve means to impart movement to the latter and an element responsive to the pressurized fluid within the pressure chamber to effectuate braking, the improvement wherein the valve means defines first and second portions exposed to pressure of the pressurizing fluid and providing a differential area responsive to the pressurized fluid within the pressure chamber to provide a force opposing movement of the valve means so as to oppose further movement of said valve means communicating pressurized fluid to said pressure chamber when the pressurized fluid reaches a predetermined value.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US93627178A | 1978-08-23 | 1978-08-23 | |
| US936,271 | 1978-08-23 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1120974A true CA1120974A (en) | 1982-03-30 |
Family
ID=25468401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000334300A Expired CA1120974A (en) | 1978-08-23 | 1979-08-23 | Pressure limiter for hydraulic brake booster |
Country Status (10)
| Country | Link |
|---|---|
| JP (1) | JPS5531692A (en) |
| AR (1) | AR221101A1 (en) |
| AU (1) | AU528916B2 (en) |
| BR (1) | BR7905409A (en) |
| CA (1) | CA1120974A (en) |
| DE (1) | DE2934205A1 (en) |
| ES (1) | ES483555A1 (en) |
| FR (1) | FR2434064A1 (en) |
| GB (1) | GB2028443B (en) |
| IT (1) | IT1122755B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3041247A1 (en) * | 1980-11-03 | 1982-06-09 | Alfred Teves Gmbh, 6000 Frankfurt | HYDRAULIC POWER AMPLIFIER |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3603209A (en) * | 1969-01-16 | 1971-09-07 | Bendix Corp | Hydraulic brake booster |
| US3688498A (en) * | 1970-09-21 | 1972-09-05 | Bendix Corp | Auxiliary fluid supply for brake booster |
| BE792060A (en) * | 1971-12-24 | 1973-03-16 | Dba Sa | ASSISTED BRAKING SYSTEM WITH FOLLOWING MECHANISM |
| US3845693A (en) * | 1973-04-23 | 1974-11-05 | Bendix Corp | Power brake boost mechanism with pressure regulating device |
| FR2332445A1 (en) * | 1975-11-21 | 1977-06-17 | Dba | HYDRAULIC AMPLIFIER |
-
1979
- 1979-07-30 GB GB7926466A patent/GB2028443B/en not_active Expired
- 1979-08-01 AU AU49446/79A patent/AU528916B2/en not_active Ceased
- 1979-08-14 IT IT25104/79A patent/IT1122755B/en active
- 1979-08-14 FR FR7920679A patent/FR2434064A1/en not_active Withdrawn
- 1979-08-22 AR AR277810A patent/AR221101A1/en active
- 1979-08-22 ES ES483555A patent/ES483555A1/en not_active Expired
- 1979-08-22 BR BR7905409A patent/BR7905409A/en unknown
- 1979-08-23 JP JP10671079A patent/JPS5531692A/en active Pending
- 1979-08-23 DE DE19792934205 patent/DE2934205A1/en not_active Withdrawn
- 1979-08-23 CA CA000334300A patent/CA1120974A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| IT7925104A0 (en) | 1979-08-14 |
| JPS5531692A (en) | 1980-03-06 |
| GB2028443A (en) | 1980-03-05 |
| AR221101A1 (en) | 1980-12-30 |
| AU528916B2 (en) | 1983-05-19 |
| DE2934205A1 (en) | 1980-03-06 |
| ES483555A1 (en) | 1980-03-01 |
| FR2434064A1 (en) | 1980-03-21 |
| IT1122755B (en) | 1986-04-23 |
| BR7905409A (en) | 1980-05-20 |
| AU4944679A (en) | 1980-02-28 |
| GB2028443B (en) | 1982-10-13 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |