GB1593079A - Booster for vehicle braking system - Google Patents

Description

(54) BOOSTER FOR VEHICLE BRAKING SYSTEM (71) We, TOKICO LTD, a Japanese body corporate of 6-3 Fujimi 1-Chome, Kawasaki-ku, Kawasaki-shi, Kanagawa-ken, Japan, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to a vehiclebrake booster of the type utilizing compressed air to generate a differential pressure across a diaphragm dividing the interior of a main body of the booster into two chambers.

A typical brake booster of thistype comprises a main body, a flexible diaphragm dividing the interior of the main body into two chambers, a valve body disposed in a housing and incorporating valve means therein for selectively connecting or not one of the cambers with the other of chambers or with a source of compressed air. The compressed air from the source of compressed air is introduced through a compressed air guiding member which projects to the outside of the booster through one end thereof, and the valve body is supported slidably in the compressed air guiding member. A complicated mounting and sealing device has been provided between the main body and the guiding member and between the guiding member and the valve body, thereby increasing manufacturing costs.

An object of the present invention is to avoid such problem.

There is provided by the present invention a brake booster device comprising: a main body, a diaphragm dividing the interior of said main body into first and second chambers; a cylindrical valve body having a bore therethrough and first and second end portions, said first end portion being connected to said diaphragm, and said second end portion extending outwardly of said main body through said first chamber; an outer first annular valve seat formed on an inner surface of said valve body adjacent said first end portion thereof; a plunger separate from said valve body and slidably fitted within said first end portion of said valve body, said plunger having an end facing toward said second end portion of said valve body, said end of said plunger having thereon an inner second annular valve seat; a compressed air guiding member of generally cylindrical form open at both ends and having a first portion extending into and resiliently urged against said valve body through said second end portion thereof, and a second portion positioned outwardly of said main body and said valve body; the guiding member being sealed to form a chamber to contain compressed air by a first seal at the end thereof within the valve body sealing that end against the interior of the valve body, and by a second seal at the other end of the guiding member sealing that end against the actuating rod; the second portion of the guiding member being formed with an integral pipe giving access to the interior of the member and directed radially of the actuating rod, for connection to a source of compressed air; a poppet valve having a seat portion urged axially toward said annular valve seats, a mounting flange portion constituting said first seal of generally "X" shaped cross-section and sealingly positioned between and fixedly retained by said valve body and said compressed air guiding member, and a flexible generally cylindrical portion integral with and joining said seat portion and said flange portion; a valve chamber between said first and second annular valve seats; first passage means extending through said valve body for connecting said first chamber with said valve chamber; second passage means extending through said valve body for connecting said second chamber with said valve chamber; and actuating rod means, axially movably extending through said compressed air guiding member and connected to said plunger, for moving said plunger axially of said valve body between a first position whereat said seat portion contacts and seats against only said second annular valve seat, said first annular valve seat is open, and said first and second chambers are in communication through said first passage means, said valve chamber, said first annular valve seat and said second passage means, and a second position whereat said seat portion contacts and seats against only said first annular valve seat, said second annular valve seat is open, and said first chamber is in communication with said means for guiding compressed air through said first passage means, said valve chamber and said second annular valve seat.

Further objects and effects of the present invention will be apparent from the following description in conjunction with the accompanying drawings showing one embodiment of the present invention, in which: Figure 1 is a longitudinal cross-sectional view of a brake booster of the embodiment of the present invention, and Figure 2 is an enlarged view of a portion of Figure 1.

The brake booster shown in Figure 1 comprises a main body 1, a flexible diaphragm 2 dividing the interior of the main body 1 into two chambers A and B, a generally cylindrical valve body 5 slidably mounted in the main body 1 and incorporating valve means 4 for selectively connecting or not one of the chambers (chamber B in the embodiment) with the other chamber or with a source 3 of compressed air, and a compressed air guiding member 6 for guiding compressed air from the source 3 to valve means 4 in the valve body 5.

A pipe la connectable to an intake manifold (not shown) of the engine of a vehicle is provided on the main body 1 to open into the chamber A. Alternatively, the pipe la may simply be open to the atmosphere but, it is advisable to connect the pipe la with the intake manifold of the engine to supply clean air into the chamber A and to increase pressure difference across the diaphragm 2 in actuating the device.

The valve body 5 extends and is slidable in through an opening 1 b in the housing 1, and a seal 7 having a generally X-shaped cross-section seals the outer periphery of the valve body from the opening lb in the housing 1.

In the valve body 5, there are provided a bore Sa, a cylinder portion 8 formed co-axially with the bore Sa, a plunger 9 fitted slidably in the cylinder portion 8, and an actuating rod 10 extending generally co-axially through the bore 5a with one end (lefthand end in the drawing) being connected pivotally to the plunger 9 and the other end thereof being connected to an actuator such as a brake lever. An outer valve seat 8a is formed on the righthand end of the cylinder portion 8 as viewed in the drawing, and an inner valve seat 9a is formed on the righthand end of the plunger 9. A poppet valve 11 having seat portion 1 la to co-operate with the valve seats 8a and 9a is mounted on the valve body 5. The poppet valve 11 and valve seats 8a and 9a constitute valve means 4 mentioned heretofore.

The poppet valve 11 includes, further to the seat portion 1 la, an annular flexible diaphragm portion 1 lib with one end being connected integrally with the seat portion 1 la, and a mounting flange 1 lc connected integrally to the other end of the diaphragm portion 1 lb.

The mounting flange 11 c engages tightly with the inner periphery of the bore 5a and the compressed air guiding member 6 as described hereinafter.

An annular space C defined between the outer and inner valve seats 8a and 9a is connected permanently with the chamber B through a radial passage 13 formed in the valve body 5.

When the poppet valve 11 is separated from the outer valve seat 8a the space C is connected with the chamber A through an axial passage 14 formed in the valve body 5, and when the poppet valve 11 is separated from the inner valve seat 9a the space C is connected with a compressed air guiding passage D in the compressed air guiding member 6 through the central opening 11 d of the poppet valve 11.

The compressed air guiding member 6 has a generally cylindrical shape with two open ends, and is received in the bore 5a of the valve body 5. A stepped portion Sb is formed on the inner periphery of the bore Sa, and a flanged portion 6a is formed on the member 6. A coil spring 15 extending between one side of the flagged portion 6a and the actuating rod 10 acts on the member 6 to urge a shoulder portion 6b formed on the member 6 against the stepped portion 5 Sb in the bore 5a, whereby the member 6 is supported fixedly in the bore 5a of the valve body 5. The movement of the actuating rod 10 in the righthand direction in the drawing is restricted by a stop 9b mounted on the plunger 9.

Annular grooves 6d and 10a are formed respectively in the outer periphery of the compressed air guiding member 6 at a position adjacent to the outer open end portion 6c and in the outer periphery of the actuating rod 10, so as to receive the opposite ends of a flexible seal or a boot 16 therein respectively. The seal 16 closes sealingly the open end portion 6c from the outside. Clamping rings 17 and 18 act to hold respective ends of the seal 16 in the grooves 6d and 10a sealingly and reliably.

An annular groove 6f is formed in the outer periphery of the compressed air guiding member 6 adjacent to the inner open end 6d thereof, and the mounting flange 1 1c of the poppet valve 11 is retained sealingly between the groove 6f and the inner periphery of the bore 5a of the valve body 5. Since the mounting flange tic engages tightly with the inner periphery of the bore 5a, a space E defined inside of the bore 5a is isolated from a space F defined between the valve body 5 and the compressed air guiding member 6. Since the mounting flange 1 lc closely contacts with the groove 6f the space D defined inside of the inner open end 6e of the member 6 is isolated from the space F which is in permanently communication with atmospheric pressure.

A compression spring 19 extends between the other side surface (lefthand surface) of the flanged portion 6a of the member 6 and the poppet valve 11 so as to urge the seating portion 1 lea toward the valve seats 8a and 9b.

A pipe 20 connected to the source 3 of compressed air is formed integrally on the compressed air guiding member 6 at a portion thereof projecting out of the valve body 5. A dust cover 21 is mounted between the main body 1 and the compressed air guiding member 6 to prevent ingress of dust or water through the opening ib or through the space F. Shown at 22 in the drawing are air filters.

In the aforesaid construction, the poppet valve 11 contacts with the inner valve seat 9a and is separated from the outer valve seat 8a in the normal or the non-actuated condition. The chamber A then communicates with the chamber B, and the chambers A and B are maintained at a vacuum pressure.

When the brake pedal is actuated by the driver of the vehicle, the actuating rod 10 move moves leftwards as seen in the drawing with the plunger 9 being accompanied thereby. The seat portion 1 a of the poppet valve 11 also moves leftward maintaining seating engagement with the inner valve seat 9a under the action of the spring 19. When the seat portion 1 la of the poppet valve 11 engages with the outer valve seat 8a, the communication between the chambers A and B is closed.Thereafter, the seat portion 11 a of the poppet valve 11 is maintained stationary with respect to the valve body 5, and only the inner valve seat 9a displaces leftward thus separating from the seat portion 11 a of the poppet valve 11, whereby the compressed air guiding passage D is opened to the chamber B through the space C, so that the compressed air from the source 3 is introduced into the chamber B. A differential pressure is generated across the diaphragm 2 to displace it leftward as seen in the drawing. Output force is transmitted to a master cylinder or the like (not shown) through an output shaft 23.

The space E is connected to the chamber A through the passage 14 permanently and is maintained at a vacuum pressure, the compressed air guiding passage D is maintained at a hyperatmospheric pressure, and the space F is maintained at atmospheric pressure. To improve sealing characteristics of the valve under those pressure conditions, the mounting flange 1 1c according to the present invention has a generally X-shaped cross-section as shown in Figure 2.

Radially inner projections, particularly the projection shown as 1 l'c in Figure 2, are tightly pressed against the peripheral surface of the member 6 according to pressure difference between the passage D and the space F, and radially outer projections of the mounting flange 1 1c, particularly the projection 11 c in Figure 2 tend to deform toward the inner peripheral surface of the bore 5a according to pressure difference between the space F and the space E, thus, the mounting flange 1 lc of the poppet valve 11 is urged tightly against the inner peripheral surface of the bore 5a and also against the outer peripheral surface or the inner surface of the groove 6f of the member 6 and satisfactory sealing characteristics are obtained.

The seal ring 7 disposed between the outer periphery of the valve body 5 and the main body 1 has also a generally X-shaped crosssection. When the chamber B is at a vacuum pressure the righthand projections 7',7' are urged tightly against the outer peripheral surface of the valve body 5 and the inner peripheral surface of the opening ib of the main body 1, respectively, due to pressure difference between opposite sides of the seal ring 7.

Similarly, when the chamber 8 is at the super-atmospheric pressure, the axially inner or the lefthand projections 7",7" are urged tightly against the outer peripheral surface of the valve body 5 and the inner peripheral surface of the opening ib of the main body 1 respectively. Therefore, it is possible to attain good sealing characteristics between the valve body 5 and the main body 1 by utilizing seal ring having X-shaped cross-section.

As described heretofore, the compressed air guiding member 6 is, according to the present invention, received in the bore 5a of the valve body 5, thus, it is possible to reduce the overall dimensions of the booster thereby saving installation space for the booster device in engine compartment of the vehicle. Further, since the mounting flange 11 c of the poppet valve 11 is sealingly retained between the compressed air guiding member 6 and the bore 5a of the valve body 5, any additional sealing member is not necessary between the valve body 5 and the member 6, and any additional members for mounting and fixing the poppet valve are not necessary since the compressed air guiding member 6 serves also to support the poppet valve.Therefore, it is possible to omit several parts as compared with conventional boosters thereby simplifying internal construction, minimizing manufacturing costs, and assuring reliable operational characteristics.

WHAT WE CLAIM IS: 1. A brake booster device comprising: a main body; a diaphragm dividing the interior of said main body into first and second chambers; a cylindrical valve body having a bore therethrough and first and second end portions, said first end portion being connected to said diaphragm, and said second end portion extending outwardly of said main body through said first chamber; an outer first annular valve seat formed on an inner surface of said valve body adjacent said first end portion thereof; a plunger separate from said valve body and slidably fitted within said first end portion of said valve body, said plunger having an end facing toward said second end pdrtion of said valve body, said end of said plunger having thereon an inner second annular valve seat; a compressed air guiding member of generally cylindrical form open at both ends and having a first portion extending into and resiliently urged against said valve body through said second end portion thereof, and a second portion positioned outwardly of said main body and said valve body; the guiding member being sealed to form a

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. dust cover 21 is mounted between the main body 1 and the compressed air guiding member 6 to prevent ingress of dust or water through the opening ib or through the space F. Shown at 22 in the drawing are air filters. In the aforesaid construction, the poppet valve 11 contacts with the inner valve seat 9a and is separated from the outer valve seat 8a in the normal or the non-actuated condition. The chamber A then communicates with the chamber B, and the chambers A and B are maintained at a vacuum pressure. When the brake pedal is actuated by the driver of the vehicle, the actuating rod 10 move moves leftwards as seen in the drawing with the plunger 9 being accompanied thereby. The seat portion 1 a of the poppet valve 11 also moves leftward maintaining seating engagement with the inner valve seat 9a under the action of the spring 19. When the seat portion 1 la of the poppet valve 11 engages with the outer valve seat 8a, the communication between the chambers A and B is closed.Thereafter, the seat portion 11 a of the poppet valve 11 is maintained stationary with respect to the valve body 5, and only the inner valve seat 9a displaces leftward thus separating from the seat portion 11 a of the poppet valve 11, whereby the compressed air guiding passage D is opened to the chamber B through the space C, so that the compressed air from the source 3 is introduced into the chamber B. A differential pressure is generated across the diaphragm 2 to displace it leftward as seen in the drawing. Output force is transmitted to a master cylinder or the like (not shown) through an output shaft 23. The space E is connected to the chamber A through the passage 14 permanently and is maintained at a vacuum pressure, the compressed air guiding passage D is maintained at a hyperatmospheric pressure, and the space F is maintained at atmospheric pressure. To improve sealing characteristics of the valve under those pressure conditions, the mounting flange 1 1c according to the present invention has a generally X-shaped cross-section as shown in Figure 2. Radially inner projections, particularly the projection shown as 1 l'c in Figure 2, are tightly pressed against the peripheral surface of the member 6 according to pressure difference between the passage D and the space F, and radially outer projections of the mounting flange 1 1c, particularly the projection 11 c in Figure 2 tend to deform toward the inner peripheral surface of the bore 5a according to pressure difference between the space F and the space E, thus, the mounting flange 1 lc of the poppet valve 11 is urged tightly against the inner peripheral surface of the bore 5a and also against the outer peripheral surface or the inner surface of the groove 6f of the member 6 and satisfactory sealing characteristics are obtained. The seal ring 7 disposed between the outer periphery of the valve body 5 and the main body 1 has also a generally X-shaped crosssection. When the chamber B is at a vacuum pressure the righthand projections 7',7' are urged tightly against the outer peripheral surface of the valve body 5 and the inner peripheral surface of the opening ib of the main body 1, respectively, due to pressure difference between opposite sides of the seal ring 7. Similarly, when the chamber 8 is at the super-atmospheric pressure, the axially inner or the lefthand projections 7",7" are urged tightly against the outer peripheral surface of the valve body 5 and the inner peripheral surface of the opening ib of the main body 1 respectively. Therefore, it is possible to attain good sealing characteristics between the valve body 5 and the main body 1 by utilizing seal ring having X-shaped cross-section. As described heretofore, the compressed air guiding member 6 is, according to the present invention, received in the bore 5a of the valve body 5, thus, it is possible to reduce the overall dimensions of the booster thereby saving installation space for the booster device in engine compartment of the vehicle. Further, since the mounting flange 11 c of the poppet valve 11 is sealingly retained between the compressed air guiding member 6 and the bore 5a of the valve body 5, any additional sealing member is not necessary between the valve body 5 and the member 6, and any additional members for mounting and fixing the poppet valve are not necessary since the compressed air guiding member 6 serves also to support the poppet valve.Therefore, it is possible to omit several parts as compared with conventional boosters thereby simplifying internal construction, minimizing manufacturing costs, and assuring reliable operational characteristics. WHAT WE CLAIM IS:

1. A brake booster device comprising: a main body; a diaphragm dividing the interior of said main body into first and second chambers; a cylindrical valve body having a bore therethrough and first and second end portions, said first end portion being connected to said diaphragm, and said second end portion extending outwardly of said main body through said first chamber; an outer first annular valve seat formed on an inner surface of said valve body adjacent said first end portion thereof; a plunger separate from said valve body and slidably fitted within said first end portion of said valve body, said plunger having an end facing toward said second end pdrtion of said valve body, said end of said plunger having thereon an inner second annular valve seat; a compressed air guiding member of generally cylindrical form open at both ends and having a first portion extending into and resiliently urged against said valve body through said second end portion thereof, and a second portion positioned outwardly of said main body and said valve body; the guiding member being sealed to form a

chamber to contain compressed air by a first seal at the end thereof within the valve body sealing that end against the interior of the valve body, and by a second seal at the other end of the guiding member sealing that end against the actuating rod; the second portion of the guiding member being formed with an integral pipe giving access to the interior of the member and directed radially of the actuating rod, for connection to a source of compressed air; a poppet valve having a seat portion urged axially toward said annular valve seats, a mounting flange portion constituting said first seal, of generally "x" shaped cross section and sealingly positioned between and fixedly retained by said valve body and said compressed air guiding member, and a flexible generally cylindrical portion integral with and joining said seat portion and said flange portion; a valve chamber between said first and second annular valve seats; first passage means extending through said valve body for connecting said first chamber with said valve chamber; second passage means extending through said valve body for connecting said second chamber with said valve chamber; and actuating rod means, axially movably extending through said compressed air guiding member and connected to said plunger, for moving said plunger axially of said valve body between a first position whereat said seat portion contacts and seats against only said second annular valve seat, said first annular valve seat is open, and said first and second chambers are in communication through said first passage means, said valve chamber, said first annular valve seat and said second passage means, and a second position whereat said seat portion contacts and seats against only said first annular valve seat, said second annular valve seat is open, and said first chamber is in communication with said means for guiding compressed air through said first passage means, said valve chamber and said second annular valve seat.

2. A brake booster as set forth in claim 1, wherein said second chamber is connected permanently to a source of vacuum pressure.

3. A brake booster as set forth in claim 1 or 2, wherein said valve body slidably projects through an opening formed in one side of the main body, with a generally X-shaped seal ring being interposed therebetween.

4. A vehicle brake booster substantially as hereinbefore described with reference to the accompanying drawing.