VEHICLE BRAKE ACTUATOR ARRANGEMENT

Abstract: The present brake actuator (20) is inserted between the brake master cylinder (10) and the usual power booster (18) in an automotive vehicle braking system. It includes a cylinder (40) for bolt-on attachment to the master cylinder housing (10) and the booster housing (44). A piston (53) in the actuator is on a shaft (64) positioned end-to-end between the shaft (51) in the booster, which is operated by the brake pedal, and the piston rod (62) of the master cylinder. This permits normal braking under the control of the brake pedal. A solenoid valve (30) mounted on the actuator housing (10) applies either atmospheric pressure or vacuum from the engine intake manifold to the interior of the actuator on one side of the piston. When vacuum is applied, the actuator piston moves in a direction to apply the brakes irrespective of the brake pedal. This happens in response to a predetermined event, such as the driver leaving the driver's seat of the vehicle.

Description: VEHICLE BRAKE ACTUATOR ARRANGEMENT FIELD OF THE INVENTION This invention relates to a novel arrangement for ap¬ plying the brakes of an automotive vehicle in response to the occurrence of a predetermined event, such as the driver leav¬ ing the driver*s seat. BACKGROUND OF THE INVENTION Typical vehicle brake systems have a master cylinder with a slidable piston whose piston rod is engaged by a shaft " extending from a power booster and operated by the brake pedal. SUMMARY OF THE INVENTION The present invention comprises an actuator engaged be¬ tween the booster and the master cylinder and including a piston on a shaft which fits end-to-end between the pedal- • operated shaft in the booster and the piston rod in the master cylinder, so that normal braking under the control of the brake pedal takes place in the usual manner. A solenoid valve controls the pressure inside the actuator at the side of its piston toward the brake cylinder. This valve is under the control of a switch (such as a seat switch) so that vacuum is applied to this side of the actuator piston, causing it to apply the brakes, whenever the event monitored by the switch takes place (such as the driver leaving the driver's seat of the vehicle) . A principal object of this invention is to provide a novel ar¬ rangement for automatically applying the brakes of a vehicle at a pre- det-≥rmined rate, with pre***det__rmined force whenever a certain pre-de- t___ ~ r_Lned event occurs while sounding an alarm, wa_ ~ _ing. ' the driver. Another object of this invention is to provide such an arrangement which does not affect normal braking operation in response to the vehicle's brake pedal. Another object of this invention is to provide such an arrangement which may be installed readily between the master cylinder and the power booster of a conventional braking sys¬ tem on an automotive vehicle. Further objects and advantages of this invention will appear from the following description and appended claims, re- ference being had to the accompanying drawings forming a part of this specification wherein like reference characters desig¬ nate corresponding parts in the several views. DESCRIPTION OF THE DRAWINGS Figure 1 is a side elevation showing the present actuat- or between a conventional brake master cylinder and a conven¬ tional power booster operated by a brake pedal; Figure 2 is a longitudinal section taken along the line 2—2 in Figure 1 with the brakes released; Figure 3 is a view similar to Figure 2 with the brakes applied; Figure 4 is a cross-section through the present actuator taken along the line 4—4 in Figure 1; and Figure 5 is a schematic diagram showing an automotive brake system which includes the present actuator and a seat switch for operating it. DETAILED DESCRIPTION Before explaining the disclosed embodiment of the pre¬ sent invention in detail, it is to be understood that the in¬ vention is not limited in its application to the details of the particular arrangement shown, since the invention is capable of other embodiments. Also, the terminology used herein is for the purpose of description and not of limitation. Referring first to Figure 5, the brake system for a passenger car or other automotive vehicle includes a brake master cylinder 10 connected through a hydraulic brake line 11 to disc brakes 12 and 13 on the front wheels and through a hydraulic brake line 14 to drum brakes 15 and 16 on the rear wheels. A piston in the master cylinder 10 is operated by a brake pedal 17 acting through a power booster 18 of known design, so that when the brake pedal is depressed the brakes on the front and rear wheels will be applied. In accordance with the present invention, a brake actua¬ tor 20 (described in detail hereinafter) is mounted between the power booster 18 and the brake master cylinder 10. As shown, the present actuator is arranged to apply the brakes when the driver of the vehicle leaves the driver's seat. A normally-open multi-contact switch 21 in the driver's seat is closed by the weight of the driver on the seat but when the driver gets out of the seat, switch 21 assumes its normally-open condition. As shown in Figure 5, one side of the seat switch 21 is connected through a manually operated switch 22 to the ungrounded terminal of the vehicle battery 23. The opposite side of switch 21 is connected through a relay coil 24 to ground. Relay coil 24 operates a mobile relay contact 25, which is connected to the manual switch 22. When seat switch 21 is open and relay coil' 24 is de-energized, the mobile relay contact 25 engages a fixed contact 26. When seat switch 21 is closed, completing the energization circuit for relay coil 24, the mobile relay contact 25 engages an open-circuited fixed contact 27. The fixed relay contact 26 is connected through a sole- noid coil 28 to ground. Solenoid coil 28 operates the plunger 29 of a vacuum valve 30. Valve 30 has a vacuum port 31 connected to a vacuum source 32, such as the vehicle engine intake manifold, a vent port 33 which is open to the atmos¬ phere, and an actuator port 34 which is connected through an air line 35 to one side of the actuator 20, as explained hereinafter. The plunger 29 carries a valve member 36 slid- ably mounted inside the housing of valve 30. When solenoid coil 28 is de-energized, valve member 36 is in the position shown in Figure 5, in which it blocks the vacuum port 31 and permits port 34 to communicate with the vent port 33. When solenoid coil 28 is energized, it pulls plunger 29 up to a position in which valve member 36 blocks the vent port 33 and permits port 34 to communicate with the vacuum port 31. As shown in Figure 1, the air line 35 may be a short pipe which mounts the solenoid valve 30 on the back wall 37 of actuator 20. The vacuum port 31 is connected through an elbow 38 and a hose 39 to the engine intake manifold (not shown) , which provides the vacuum source shown schematically at 32 in Figure 1. Referring to Figure 2, the generally flat back wall 37 " is bolted in airtight fashion to the flanged end of a general¬ ly cylindrical side wall 40 of the actuator housing. The op¬ posite end of this side wall is joined to a generally flat front wall 41 of the actuator housing which extends parallel to its back wall 37. The front wall 41 of the actuator hous- ing presents a cylindrical central collar 42 which is snugly received in a complementary opening 43 formed in the back wall 44 of the casing of power booster 18. Bolts 45 attach the front wall 41 of the actuator housing to the back wall 44 of the booster housing, and a gasket 46 is clamped be- tween them to provide an airtight seal. The collar 42 de¬ fines a circular opening 47 which slidably receives a shaft 48 extending from the interior of the booster 18 behind the latter's flexible diaphragm 49 into the interior of the actu¬ ator housing. Shaft 48 is formed with a cylindrical recess 50 which snugly receives the reduced end of a shaft 51 inside the booster. The opposite end of shaft 51 is pivotally coupled at 52 (Figure 5) to the brake pedal 17. The booster diaphragm 49 is engaged between the end of shaft 48 and an annular transverse flange 51a on shaft 51. Inside the actuator housing a flat piston 53 on shaft 48 carries an O-ring 54 of rubber-like material in a peripher¬ al groove 55. This O-ring slidably engages the inside of the cylindrical side wall 40 of the actuator housing in airtight fashion. A coil spring 56 is engaged under compression be- tween the back wall 37 of the actuator housing and the pis¬ ton 53 to bias the piston away from the back wall 37, as shown in Figure 2. The back wall 37 of the actuator housing is formed with a central circular opening 57 which is the same size as, and coaxial with, the opening 43 in the back wall 44 of the booster housing. The housing of the brake master cylinder 10 has a cylindrical neck 58 which is snugly received in the actuator's back wall opening 57. The master cylinder hous¬ ing has a transverse annular flange 59 which is attached to the outside of the back wall 37 of the actuator housing by bolts 60, with a gasket 61 clamped between them to provide an airtight seal. The bolts 60 are the same size and are at the same locations as the bolts 45 attaching the actuator housing to the booster housing. If the present actuator 20 were not in place, the flange 59 on the master cylinder hous¬ ing would be bolted directly to the rear wall 44 of the booster housing, with the neck 58 on the master cylinder housing received in the opening 43 in the rear wall of the booster housing. This is how the master cylinder is attached to the booster in the usual brake installations which lack the present actuator 20. The master cylinder piston has a piston, rod 62 with a cylindrical recess 63 in its outer end which snugly receives a reduced end 64 of shaft 48 in the present actuator 20. Recess 63 is the same size as recess 50 in the opposite end of shaft 48. If actuator 20 were not present, the recess 63 in the end of the master cylinder piston rod 62 would re¬ ceive the reduced end of shaft 51 in the booster 18. As already mentioned, the air line 35 is connected through the back wall 37 of the actuator housing to the in¬ terior of actuator 20 between its back wall 37 and its piston 53. When the solenoid coil 28 is de-energized, this space will be vented to the atmosphere via air line 35, port 34 of solenoid valve 30 (Figure 5) and vent port 33 of this valve. Under these circumstances, spring 56 will bias piston 53 away from the actuator back wall 37, to the position shown in Figure 2. Whenever the brake pedal 17 is depressed, its movement will be transmitted through shafts 51 and 48 to the master cylinder piston rod 62 to move the piston in the master cylinder to apply the brakes. The bias spring 56 does not exert a significant opposing force against this operation. When the solenoid coil 28 is energized, plunger 29 is pulled up in Figure 5 to a position in which valve member 36 blocks the vent port 33 and connects port 34 to the vacuum source 32 via port 31. Consequently, vacuum will be applied via air line 35 to the space inside actuator 20 between its back wall 37, and piston 58, causing piston 53 to move to the position shown in Figure 3. This piston movement is applied via shaft 48 and piston rod 62 to the master cylinder piston, applying the brakes. In the system shown in Figure 5, this would happen whenever the seat switch 21 seen in Figure 1 opens, i.e., when the vehicle driver leaves the driver's seat. The same operation could be achieved in response to a switch other than a seat switch. For example , on a bus the seat switch 21 in Figure 5 might be replaced by a door switch which is closed when the door is closed and opens when the door is opened. On a fuel truck the seat switch 21 in Figure 5 might be replaced by a switch which opens when the nozzle of the fuel hose is removed from its cradle on the truck . On passenger automobiles , the switch could be connected to the existing warning system on the dash panel , such as engine overheating, low oil pressure , door open, low tire pressure , brake wear, brake failure , antitheft device , or electronically after the vehicle has stopped, etc . or attached to the inte¬ grated warning (systems) which will be present on most auto¬ mobiles by the mid 1980 ' s . Also , the seat switch in the Fig- ure 5 control system might be replaced by a radar operated switch which opens to apply the vehicle brakes whenever the vehicle is too close to another vehicle ahead of it . From the foregoing detailed description and the drawings, it will be evident that the switch-operated actuator 20 may be installed in a conventional braking system on a vehicle with very little modification. No structural change in the booster or the master cylinder is required because the actuator 20 fits them the same way they fit each other when the actuator is not present.

Claims: I CLAIM: 1. In a vehicle braking system having a brake pedal, a master cylinder having a housing and a slidable piston therein, and a power booster having a housing and operatively connected between the brake pedal and the piston in the master cylinder to operate " said master cylinder piston in response to the brake pedal, the improvement which comprises: an actuator operatively engaged between said booster and said piston in the master cylinder to couple said brake pedal to said piston, said actuator having a housing engaged between the booster housing and the master cylinder housing, and said actuator having a movable pressure-respon¬ sive member in its housing operatively coupled to said piston in the master cylinder for moving the latter; a valve operatively connected to the interior of said actuator to control the movement of said pressure- responsive member therein; and switch means for selectively controlling the operation of said valve. 2. The apparatus of claim 1, wherein: said valve has an actuator port connected to the interior of said actuator housing at one side of said movable pressure-responsive member therein, a vent port connected to the atmos¬ phere, a vacuum port connected to a vacuum source, a valve member movable between a first position blocking said vacuum port and connect¬ ing said actuator port to said vent port and a second position blocking said vent port and connecting said actuator port to said vacuum port, and a solenoid coil controlling the position of said valve member and operatively connected to said switch to move said valve member from said first position to said second position in response to a pre-determined operation of said switch, whereby to apply vacuum to the interior of said actuator housing at one side of said movable pressure-responsive member therein to move said pressure-responsive member. in a direction for applying the brakes. 3. The apparatus of claim 2, wherein said valve is mounted on said actuator housing. 4. The apparatus of claim 1, wherein: said booster has a reciprocable shaft operatively coupled to the brake pedal to move in response to movement of the brake pedal; said piston in the master cylinder has a piston rod reciprocable in the master cylinder; said actuator has a shaft extending end-to-end between said shaft in the booster and said piston rod to impart the brake pedal movement directly to the master cylinder piston; and said shaft in the actuator is coupled to said pressure-responsive member in the actuator to impart the latter • s movement to the master cylinder piston. 5. The apparatus of claim 4, wherein: said actuator housing is a cylinder; and said pressure-responsive member in the actuator is a piston slidable in said last-mentioned cylinder and attached to said shaft in the actuator. 6. The apparatus of claim 5, wherein: said master cylinder,housing at its end toward said actuator has a transverse flange presenting bolt holes and terminates in an annular end neck beyond said flange which slidably re¬ ceives said shaft in the actuator; said booster housing at its end toward said actu¬ ator has a central opening shaped and dimen¬ sioned complementary to said end neck on the master cylinder housing and has bolt holes, at at the same locations as said bolt holes in said transverse flange on the master cylinder housing; the actuator housing at its end toward said master cylinder has: (a) a central opening the same size as said central opening in the " booster housing and snugly receiving said end neck on the master cylinder housing, and (b) bolt holes at the same locations as said bolt holes in said transverse flange on the master cylinder housing; the actuator housing at its end toward said booster has: (a) an annular neck snugly received in said central opening in the adjacent end of the booster housing, and (b) bolt holes at the same locations as said bolt holes in the adjacent end of the booster housing; and said shaft in the actuator extends slidably through said neck on the actuator housing into « the booster housing. 7. The apparatus of claim 6, wherein said shaft in the actuator has: a recess in its end inside the booster housing re¬ ceiving a reduced end on said shaft in the booster housing; and a reduced opposite end received in a recess in the adjacent end of the piston rod in the master cylinder. 8. The apparatus of claim 5, wherein: said valve has an actuator port connected to the interior of said actuator housing at one side of said piston therein, a vent port connected to a vacuum sou.ce, a valve member movable between a first position blocking said vacuum port and connecting said actuator port to said vent port and connecting said actuator port to said vacuum port, and a solenoid coil control- ling the position of said valve member and operatively connected to said switch to move said valve member from said first position to said second position in response to a pre¬ determined operation of said switch, whereby to apply vacuum to the interior of said actu¬ ator housing at one side of said piston therein to move said last-mentioned piston in a direction for applying the brakes. 9. The apparatus of claim 8, wherein said valve is mounted on the actuator housing. 10. The apparatus of claim 8, wherein: said master cylinder housing at its end toward said actuator has a transverse flange presenting bolt holes and terminates in an annular end neck beyond said flange which slidably re¬ ceives said shaft in the actuator; said booster housing at its end toward said actua¬ tor has a central opening shaped and dimen¬ sioned complementary to said end neck on the master cylinder housing and has bolt holes at the same locations as said bolt holes in said transverse flange on the master cylinder hous¬ ing; the actuator housing at its end toward said master cylinder has: (a) a central opening the same size as said central opening in the booster housing and snugly receiving said end neck on the master cylinder housing, and (b) bolt holes at the same locations as said bolt holes in said transverse flange on the master cylinder housing; the actuator housing at its end toward said booster has: (a) an annular neck snugly received in said central opening in the adjacent end of the booster housing, and (b) bolt holes at the same locations as said bolt holes in the adjacent end of the booster housing; and said shaft in the actuator extends slidably through said neck on the actuator housing into the booster housing. 11. The apparatus of claim 10, wherein said shaft in the actuator has: a recess in its end inside the booster housing receiving a reduced end on said shaft in the booster housing; and a reduced opposite end received in a recess in the adjacent end of the piston rod in the master cylinder. 12. A vehicle brake actuator arrangement for use in a vehicle braking system having a brake pedal, a power booster in¬ cluding a reciprocable shaft operatively coupled to said brake pedal to be moved thereby, and a master cylinder having a pis- ton slidable therein for applying the brakes and a piston rod extending from said piston toward said shaft of the power booster, said booster and said master cylinder each having a housing, said brake actuator arrangement comprising: an actuator housing adapted to be mounted between said booster housing and said master cylinder housing; an actuator piston slidable in said actuator housing; an actuator shaft attached to said actuator piston and adapted to be engaged end-to-end between said shaft of the power booster and said piston rod of the master cylinder to transmit the brake pedal movement to the master cylin¬ der piston; and a valve operatively connected to the interior of said actuator housing on one side of said actuator piston for controlling the air for moving the actuator piston and shaft in a brake-applying direction independent of the brake pedal. 13. A brake actuator arrangement according to claim 12 wherein said valve is mounted on said actuator housing. 14. The brake actuator arrangement of claim 12, wherein: said valve has an actuator port connected to the interior of said actuator housing at one side of said piston therein, "a vent port con¬ nected to the atmosphere, a vacuum port for connection to a vacuum source, a valve member movable between a first position blocking said vacuum port and connecting said actuator port to said vacuum port, and a solenoid coil controlling the position of said valve member to move said valve member from said first position to said second position in response to a pre-determined condition, whereby to a Pply vacuum to the interior of said actuator housing at one side of said actuator piston to move said actuator piston in a direction for applying the brakes. 15. The brake actuator arrangement of claim 14, wherein said valve is mounted on said actuator housing. 16. A brake actuator arrangement according to claim 12, wherein: said actuator housing at one end has a central opening for receiving an end neck on the master cylinder housing and bolt holes for registration with corresponding bolt holes in the master cylinder housing; said actuator housing at its opposite end has an annular neck for insertion in a central open- ing in the adjacent end of the booster hous¬ ing and bolt holes for registration with corresponding bolt holes in the adjacent end of the booster housing; and said actuator shaft extends through said cen- tral opening in said one end of the actuator housing and extends slidably through said neck on the opposite end of the actuator housing. 17. A brake actuator arrangement according to claim , wherein: said actuator shaft has a reduced extension in one end for reception in an end recess in the master cylinder piston rod and a recess in its opposite end for receiving a reduced extension on said booster shaft. 18. A brake actuator arrangement according to claim , wherein: said valve has an actuator port connected to the interior of said actuator housing at one side of said actuator, a vent port connected to the atmosphere, a vacuum port for connection to a vacuum source, a valve member movable between a first poε tion blocking said vacuum port and connecting said actuator port to said vent port and a second position block¬ ing said vent port and connecting said actua¬ tor port to said vacuum port, and a solenoid coil controlling the position of said valve member to move said valve member from said first position to said second position in response to a pre-determined condition, where¬ by to apply vacuum to the interior of said actuator housing at one side of said actua¬ tor piston to move said actuator piston in a direction for applying the brakes.

Inventors: FONTAINE WILLIAM G, FONTAINE, WILLIAM, G.
Applicants: FAIL SAFE BRAKE CORP, FAIL SAFE BRAKE CORPORATION
Application year: 1985
Main classification: B60T7
IPC codes: B60T7, B60T8, B60T13