US20010025565A1 - Brake booster - Google Patents
Brake booster Download PDFInfo
- Publication number
- US20010025565A1 US20010025565A1 US09/814,375 US81437501A US2001025565A1 US 20010025565 A1 US20010025565 A1 US 20010025565A1 US 81437501 A US81437501 A US 81437501A US 2001025565 A1 US2001025565 A1 US 2001025565A1
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- United States
- Prior art keywords
- pressure chamber
- valve
- movable member
- variable pressure
- plunger
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- 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.)
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Classifications
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- 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
- B60T13/66—Electrical control in fluid-pressure brake systems
- B60T13/72—Electrical control in fluid-pressure brake systems in vacuum systems or vacuum booster units
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- 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
- B60T13/24—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 gaseous
- B60T13/46—Vacuum systems
- B60T13/52—Vacuum systems indirect, i.e. vacuum booster units
- B60T13/573—Vacuum systems indirect, i.e. vacuum booster units characterised by reaction devices
- B60T13/575—Vacuum systems indirect, i.e. vacuum booster units characterised by reaction devices using resilient discs or pads
Definitions
- the present invention relates to a control-type brake booster capable of automatically increasing and decreasing braking power by electromagnetically operating an atmospheric valve or vacuum valve.
- a brake booster is disclosed in Japanese Patent Laid-open No. 7-503214 (1995), in which a valve body contains a solenoid mechanism with a member movable by applying electricity to the solenoid of the solenoid mechanism, and a movement of the movable member opens a to valve mechanism, which may be an atmospheric valve or vacuum valve, independently of the valve operation by movements of the input rod connected to the brake pedal.
- a valve body contains a solenoid mechanism with a member movable by applying electricity to the solenoid of the solenoid mechanism, and a movement of the movable member opens a to valve mechanism, which may be an atmospheric valve or vacuum valve, independently of the valve operation by movements of the input rod connected to the brake pedal.
- the braking power output from a brake booster when its valve mechanism is operated by movements of the input rod connected to the brake pedal can also be adjusted across a wide range when operated by the activation of the solenoid mechanism.
- the solenoid mechanism merely functions to open the valve mechanism to the degree determined by the magnitude of electric current supplied to the solenoid, and no correlation (or proportional relationship) exists between the magnitude of the electric current supplied to the solenoid mechanism and the magnitude of the braking power output from the brake booster.
- a makeshift measure to obtain a desired magnitude of braking power from a brake booster when its solenoid mechanism is operated is to control the operation of the solenoid mechanism based on a feed-back signal indicating the braking power being output from the brake booster, for instance, on an output signal from a master cylinder pressure sensor provided for detecting pressure of braking liquid output from the master cylinder.
- the present invention aims to eliminate the drawbacks in the above-mentioned conventional brake booster.
- An object of the present invention is to provide a brake booster that, while being simple in construction, can fully adjust the braking power across a wide range when its solenoid mechanism is operated.
- a brake booster wherein an interior of a shell is divided into a constant pressure chamber and a variable pressure chamber by a power piston, and a valve mechanism for controlling supply of operating fluid to the variable pressure chamber by a shifting movement of a plunger connected to an input rod cooperating with a brake pedal is provided within a valve body supported by the power piston, so that a thrust force generated on the power piston by pressure difference between the variable pressure chamber and the constant pressure chamber based on an operation of the valve mechanism is output as a booster output force (thrust output force).
- the brake booster further comprises an electromagnetic biasing means having a movable member for operating the valve mechanism independently from an operation of the input rod, and a reaction force mechanism for applying reaction force corresponding to the pressure difference between the variable pressure chamber and the constant pressure chamber to the movable member, whereby the reaction force mechanism applies the reaction force to the movable member so that an increasing rate of the booster output force is in accord with an increasing rate of the reaction force applied to the movable member.
- the reaction force mechanism applies the reaction force to the movable member at the same time or with a delay after the booster outputs force.
- the booster output force becomes proportional to the magnitude of the electric current supplied to the electromagnetic biasing mechanism. Further, since the reaction force is exerted on the movable member so that the booster output force increasing rate is in accord with the reaction force increasing rate acting on the movable member, or, so that the reaction force is created at the same time or after the booster output force is generated, the booster output force generated is not prevented by the reaction force.
- the reaction force mechanism is provided with at least one passage providing communication between a pressure chamber formed at one end of the movable member and the variable pressure chamber.
- the at least one passage has a limited flow area for limiting air flowing into the pressure chamber.
- the total flow area of the passage is designed 0.5-10 square millimeters.
- FIG. 1 is a partially enlarged sectional view showing a brake booster of one embodiment according to the present invention (a partial enlarged view of FIG. 2);
- FIG. 2 is a partial sectional view showing the brake booster of the same embodiment according to the present invention (a partially enlarged view of FIG. 3);
- FIG. 3 is a sectional view showing the brake booster of the same embodiment of the present invention.
- FIG. 4 is an enlarged cross-sectional view of X-X line in FIG. 1.
- a brake booster shown on FIGS. 1 through 4 is a tandem type and has a shell 1 which is divided into a front chamber and a rear chamber by a center shell 2 . These two respective chambers are further divided into constant pressure chambers 7 , 8 and variable pressure chambers 9 , 10 by power pistons 5 , 6 having diaphragms 3 , 4 .
- the power pistons 5 , 6 support a valve body 11 that comprises a large diameter cup portion 11 a and a small diameter cylindrical portion 11 b connected thereto.
- the valve body 11 is disposed such that the cup portion 11 a thereof sealingly and slidably passes through the center shell 2 , and that the cylindrical portion 11 b thereof sealingly and slidably passes through a cylindrical support portion 1 a arranged on the rear side of the shell 1 and extends rearwardly of the support portion.
- the valve body 11 is formed with a constant pressure passage (negative pressure passage) 12 that provides communication between the two constant pressure chambers 7 and 8 and between the constant pressure chambers 7 , 8 and the inside of the cylindrical portion 11 b of the valve body 11 .
- the valve body 11 is also formed with an atmosphere passage 13 that provides communication between the two variable pressure chambers 9 and 10 and between the two variable pressure chambers 9 , 10 and the inside of the cylindrical portion 11 b of the valve body 11 .
- Negative pressure e.g. negative pressure from the engine, is introduced into the constant pressure chamber 7 shown on the left side (front side) of the Figures.
- the negative pressure is also introduced into the constant pressure chamber 8 shown on the right side (rear side) of the Figures via the negative pressure passage 12 .
- the atmosphere is introduced into the cylindrical portion 11 b of the valve body 11 through a filter unit 14 having a silencing function.
- the atmosphere is supplied into the two variable pressure chambers 9 and 10 through the atmosphere passage 13 by operation of valve mechanism 15 (as described later).
- the valve mechanism 15 is connected to an input rod 16 cooperating with a brake pedal (not shown), which comprises: a plunger 18 slidable along a hollow guide 17 (as described later) disposed in the valve body 11 ; an annular atmospheric valve seat 19 formed at rear end of the plunger 18 ; a cylindrical valve seat member 21 slidably inserted into the valve body 11 via a seal member 20 ; an annular negative pressure valve seat 22 formed at rear end of the valve seat member 21 , a poppet valve 26 whose proximal end portion is fixed to the cylindrical portion 11 b of the valve body 11 by means of a ring member 23 and a pressing member 24 and which is usually biased to sit on the atmospheric valve seat 19 and the negative pressure valve seat 22 by means of a valve spring 25 held at one end thereof onto the input rod 16 .
- the atmospheric valve seat 19 and the annular inner portion formed at the distal end of the poppet valve 26 resting thereon constitute an atmospheric valve 27 .
- the negative pressure valve seat 22 and the annular outer portion formed at the distal end of the poppet valve 26 resting thereon constitute a vacuum valve 28 .
- the atmosphere or the negative pressure is selectably supplied into the two variable pressure chambers 9 , 10 when the atmospheric valve 27 or the vacuum valve 28 is opened, respectively.
- a return spring 29 is placed between the pressing member 24 and the input rod 16 (see FIG. 2).
- the plunger 18 is forced so as to abut the atmospheric valve seat 19 onto the poppet valve 26 by a biasing force of the return spring 29 and the valve spring 25 during a rest state of the brake booster.
- a solenoid mechanism (electromagnetic biasing means) 30 is disposed in the cup portion 11 a of the valve body 11 .
- the solenoid mechanism 30 substantially comprises: a solenoid 31 ; a housing 32 containing the solenoid 31 therein; and an annular movable member (an armature) 34 having a seal member 33 in the housing 32 (see FIG. 1) and being slidably disposed in the housing 32 .
- the housing 32 comprises: a double cylindrical shaped main body portion 35 containing the solenoid 31 therein; an extension cylindrical portion 36 extending rearward from the rear end of the main body portion 36 ; and a separating portion 37 separating the main body portion 35 thereof from the extension cylindrical portion 36 .
- the hollow guide 17 is disposed inside of the main body 35 of the housing 32 .
- the hollow guide 17 comprises a large end portion 42 engaged with a step portion 35 a of the main body 35 and a small diameter axis portion 43 extending from the large end portion 42 rearwardly through the separating portion 37 of the housing 32 (see FIG. 2).
- the plunger 18 is slidably inserted into the small diameter axis portion 43 .
- a stop key 44 extending the radial direction is inserted into the valve body 11 through the atmosphere passage 13 , and the distal end portion of the stop key 44 is connected to the plunger 18 .
- the proximal end portion of the stop key 44 is arranged to abut against a stopper plate 45 (see FIG.
- the maximum setback position of the plunger 18 is the position where the stop key 44 abuts against the stopper plate 45 .
- the stop key 44 is also inserted through a opening (long face hole) 21 a.
- the valve seat member 21 is allowed to move relatively to the plunger 18 within the range where the stop key 44 is movable within the opening 21 a.
- a reaction disk 46 and a large diameter proximal end portion 47 a of an output rod 47 are disposed on the forward side of the step portion 35 a of the main body 35 of the housing 32 .
- the distal end portion of the output rod 47 is extended forwardly through the front side of the shell 1 air-tightly.
- the distal end portion of the output rod 47 is connected to and is simultaneously moved with a piston of a master cylinder (not shown). Further, the proximal end large diameter portion 47 a of the output rod 47 and the reaction disk 46 are restrained from coming out of the housing 32 by means of a retainer 48 press-fixed on the front end of the valve body 11 by means of the return spring 41 .
- a recess 42 a is formed in the front face of the large end portion 42 of the hollow guide 17 .
- a pressure receiving plate 49 is disposed in the recess 42 a.
- a depth of the recess 42 a is designed slightly more than the thickness of the pressure receiving plate 49 .
- the front end of the plunger 18 is located slightly forwardly from the bottom of the recess 42 a when the brake booster is in its rest state. A little gap “S” (see FIG. 1) is formed between the pressure receiving plate 49 and the reaction disk 46 in such a state.
- pins 50 one ends of which are inserted and fixed into the movable member 34 of the solenoid mechanism 30 and the other ends of which are inserted into through-holes 51 formed in the separating portion 37 in the housing 32 .
- the valve seat member 21 having the negative pressure valve seat 22 at its rear end is urged forwardly by means of a spring 52 fixed to the plunger 18 at its one end.
- the front end of the valve seat member 21 is normally placed in abutment against the separating portion 37 in the housing 32 .
- the through-holes 51 of the separating portion 37 of the housing 32 are formed in alignment with the front end of the valve seat member 21 .
- the other ends of the pins 50 inserted into the through-holes 51 face the valve seat member 21 with a small gap therebetween.
- the movable member 34 of the solenoid mechanism 30 is moved rearwardly by energizing the solenoid 31 , whereby the pins 50 fixed to the movable member 34 move the valve seat member 21 rearwardly against the urging force from the spring 52 and the valve spring 25 . Consequently, the poppet valve 26 is separated from the atmospheric valve seat 19 formed at the rear end of the plunger 18 .
- the atmospheric valve 27 opens independently of the movement of the plunger 18 , that is, the movement of the input rod 16 .
- a seal member 53 held on the inner circumference of the movable member 34 provides sealing between the movable member 34 and the hollow guide 17 .
- the outer circumference of the movable member 34 is sealed by the seal member 33 against the housing 32 .
- two pressure chambers 54 and 55 are formed at both ends of the movable member 34 respectively.
- the pressure chamber 54 formed on the front side of the movable member 34 communicates with the constant pressure chamber 7 provided on the front side through a passage 56 formed in the housing 32 .
- the pressure chamber 55 formed on the rear side of the movable member 34 communicates with the variable pressure chambers 10 , 9 through a passage 57 formed in the separating portion 37 of the housing 32 .
- the brake booster is installed in a vehicle (not shown) by means of plural stud bolts 58 provided on the backside face of the shell 1 (see FIG. 3), and a brake pedal (not shown) is connected to the input rod 16 in this state. Further, a master cylinder (not shown) is attached to the brake booster by means of a stud bolt 59 provided on the front side face of the shell 1 . The output rod 47 is connected to a piston in the master cylinder in this state.
- the electromagnetic force acting on the movable member 34 exceeds the total spring force of the spring 52 and the valve spring 25 , and the movable member 34 is shifted toward the rear side, whereby the pin 50 fixed thereto moves the valve seat member 21 towards the rear side.
- the poppet valve 26 is separated from the atmospheric valve seat 19 formed at the rear end of the plunger 18 to open the atmospheric valve 27 , thereby introducing air into the variable pressure chambers 10 , 9 and creating a pressure difference between the variable pressure chambers 10 , 9 and the constant pressure chambers 7 , 8 . Consequently, the power pistons 5 , 6 advance and generate thrust force which is transmitted to the output rod 47 through the valve body 11 , thereby starting the braking action.
- the booster output force becomes proportional to the electric current supplied to the solenoid 31 , by changing the electric current supplied to the solenoid 31 across a wide range, the booster output force can be adjusted across a wide range as well.
- the construction of the brake booster can be simplified and the brake booster can be made cheaper.
- the total passage area of the passages 57 formed in the separating portion 37 of the housing 32 and the gaps around the pins 50 in the through-holes 51 is made small so that the booster output force will increase at the same rate as the reaction force acting on the movable member 34 increases, or so that an adequate reaction force will be created at the same time or after the booster output force is generated. Thereby, until a sufficient booster output force is generated in response to the electric current supplied to the solenoid 31 , the atmospheric valve 27 is kept open widely, improving the braking response. It is preferable that the total flow area of the passages 57 and the gaps around the pins 50 in the through-holes 51 is about 0.5-10 square millimeters.
- the brake booster of this invention is constructed so that the booster output force increases at the same rate as the reaction force acting on the movable member 34 increases, or so that an adequate reaction force is created at the same time or after the booster output force is generated, thereby improving the braking response in the automatic braking mode and increasing the reliability of the brake booster.
- the passages 57 formed in the separating portion 37 of the housing 32 and the gaps around the pins 50 in the through-holes 51 function to introduce air into the pressure chamber 55 . It should however be appreciated that only one of the passages 57 formed in the separating portion 37 of the housing 32 or the gaps around the pins 50 in the through-holes 51 may function to introduce air into the pressure chamber 55 .
Abstract
Description
- The present invention relates to a control-type brake booster capable of automatically increasing and decreasing braking power by electromagnetically operating an atmospheric valve or vacuum valve.
- An example of such a brake booster is disclosed in Japanese Patent Laid-open No. 7-503214 (1995), in which a valve body contains a solenoid mechanism with a member movable by applying electricity to the solenoid of the solenoid mechanism, and a movement of the movable member opens a to valve mechanism, which may be an atmospheric valve or vacuum valve, independently of the valve operation by movements of the input rod connected to the brake pedal.
- It has been desired that as is the braking power output from a brake booster when its valve mechanism is operated by movements of the input rod connected to the brake pedal, the braking power output from a brake booster having the above-mentioned solenoid mechanism can also be adjusted across a wide range when operated by the activation of the solenoid mechanism.
- However, in the above-mentioned conventional brake booster, the solenoid mechanism merely functions to open the valve mechanism to the degree determined by the magnitude of electric current supplied to the solenoid, and no correlation (or proportional relationship) exists between the magnitude of the electric current supplied to the solenoid mechanism and the magnitude of the braking power output from the brake booster.
- As a makeshift measure to obtain a desired magnitude of braking power from a brake booster when its solenoid mechanism is operated is to control the operation of the solenoid mechanism based on a feed-back signal indicating the braking power being output from the brake booster, for instance, on an output signal from a master cylinder pressure sensor provided for detecting pressure of braking liquid output from the master cylinder.
- However, since an additional sensor is required that functions like the master cylinder pressure sensor to output a signal indicating the braking power being output from the brake booster, the entire system becomes more expensive.
- The present invention aims to eliminate the drawbacks in the above-mentioned conventional brake booster. An object of the present invention is to provide a brake booster that, while being simple in construction, can fully adjust the braking power across a wide range when its solenoid mechanism is operated.
- According to one aspect of the present invention, there is provided a brake booster wherein an interior of a shell is divided into a constant pressure chamber and a variable pressure chamber by a power piston, and a valve mechanism for controlling supply of operating fluid to the variable pressure chamber by a shifting movement of a plunger connected to an input rod cooperating with a brake pedal is provided within a valve body supported by the power piston, so that a thrust force generated on the power piston by pressure difference between the variable pressure chamber and the constant pressure chamber based on an operation of the valve mechanism is output as a booster output force (thrust output force).
- The brake booster further comprises an electromagnetic biasing means having a movable member for operating the valve mechanism independently from an operation of the input rod, and a reaction force mechanism for applying reaction force corresponding to the pressure difference between the variable pressure chamber and the constant pressure chamber to the movable member, whereby the reaction force mechanism applies the reaction force to the movable member so that an increasing rate of the booster output force is in accord with an increasing rate of the reaction force applied to the movable member.
- According to another aspect of the present invention, in a brake booster having the electromagnetic biasing means mentioned above and the reaction force mechanism mentioned above, the reaction force mechanism applies the reaction force to the movable member at the same time or with a delay after the booster outputs force.
- In the above two aspects of the present invention in which the reaction force corresponding to the pressure difference between the variable pressure chamber and the constant pressure chamber is exerted on the movable member, the booster output force becomes proportional to the magnitude of the electric current supplied to the electromagnetic biasing mechanism. Further, since the reaction force is exerted on the movable member so that the booster output force increasing rate is in accord with the reaction force increasing rate acting on the movable member, or, so that the reaction force is created at the same time or after the booster output force is generated, the booster output force generated is not prevented by the reaction force.
- In the present invention, the reaction force mechanism is provided with at least one passage providing communication between a pressure chamber formed at one end of the movable member and the variable pressure chamber. The at least one passage has a limited flow area for limiting air flowing into the pressure chamber. Preferably, the total flow area of the passage is designed 0.5-10 square millimeters.
- Limiting the flow area of the passage as above, the timing of the reaction force exerted on the movable member is adjusted properly, and thus a better response of automatic braking can be established.
- FIG. 1 is a partially enlarged sectional view showing a brake booster of one embodiment according to the present invention (a partial enlarged view of FIG. 2);
- FIG. 2 is a partial sectional view showing the brake booster of the same embodiment according to the present invention (a partially enlarged view of FIG. 3);
- FIG. 3 is a sectional view showing the brake booster of the same embodiment of the present invention; and
- FIG. 4 is an enlarged cross-sectional view of X-X line in FIG. 1.
- Now, a brake booster according to an embodiment of the present invention will be explained with reference to FIGS. 1 through 4.
- A brake booster shown on FIGS. 1 through 4 is a tandem type and has a shell1 which is divided into a front chamber and a rear chamber by a
center shell 2. These two respective chambers are further divided intoconstant pressure chambers variable pressure chambers power pistons diaphragms 3,4. Thepower pistons valve body 11 that comprises a largediameter cup portion 11 a and a small diametercylindrical portion 11 b connected thereto. Thevalve body 11 is disposed such that thecup portion 11 a thereof sealingly and slidably passes through thecenter shell 2, and that thecylindrical portion 11 b thereof sealingly and slidably passes through acylindrical support portion 1 a arranged on the rear side of the shell 1 and extends rearwardly of the support portion. - The
valve body 11 is formed with a constant pressure passage (negative pressure passage) 12 that provides communication between the twoconstant pressure chambers constant pressure chambers cylindrical portion 11 b of thevalve body 11. Thevalve body 11 is also formed with anatmosphere passage 13 that provides communication between the twovariable pressure chambers variable pressure chambers cylindrical portion 11 b of thevalve body 11. Negative pressure, e.g. negative pressure from the engine, is introduced into theconstant pressure chamber 7 shown on the left side (front side) of the Figures. The negative pressure is also introduced into theconstant pressure chamber 8 shown on the right side (rear side) of the Figures via thenegative pressure passage 12. On the other hand, the atmosphere is introduced into thecylindrical portion 11 b of thevalve body 11 through afilter unit 14 having a silencing function. The atmosphere is supplied into the twovariable pressure chambers atmosphere passage 13 by operation of valve mechanism 15 (as described later). - The
valve mechanism 15 is connected to aninput rod 16 cooperating with a brake pedal (not shown), which comprises: aplunger 18 slidable along a hollow guide 17 (as described later) disposed in thevalve body 11; an annularatmospheric valve seat 19 formed at rear end of theplunger 18; a cylindricalvalve seat member 21 slidably inserted into thevalve body 11 via aseal member 20; an annular negativepressure valve seat 22 formed at rear end of thevalve seat member 21, apoppet valve 26 whose proximal end portion is fixed to thecylindrical portion 11 b of thevalve body 11 by means of aring member 23 and apressing member 24 and which is usually biased to sit on theatmospheric valve seat 19 and the negativepressure valve seat 22 by means of avalve spring 25 held at one end thereof onto theinput rod 16. Theatmospheric valve seat 19 and the annular inner portion formed at the distal end of thepoppet valve 26 resting thereon constitute anatmospheric valve 27. The negativepressure valve seat 22 and the annular outer portion formed at the distal end of thepoppet valve 26 resting thereon constitute avacuum valve 28. The atmosphere or the negative pressure is selectably supplied into the twovariable pressure chambers atmospheric valve 27 or thevacuum valve 28 is opened, respectively. Meanwhile, areturn spring 29 is placed between thepressing member 24 and the input rod 16 (see FIG. 2). Theplunger 18 is forced so as to abut theatmospheric valve seat 19 onto thepoppet valve 26 by a biasing force of thereturn spring 29 and thevalve spring 25 during a rest state of the brake booster. - A solenoid mechanism (electromagnetic biasing means)30 is disposed in the
cup portion 11 a of thevalve body 11. Thesolenoid mechanism 30 substantially comprises: asolenoid 31; ahousing 32 containing thesolenoid 31 therein; and an annular movable member (an armature) 34 having a seal member 33 in the housing 32 (see FIG. 1) and being slidably disposed in thehousing 32. Thehousing 32 comprises: a double cylindrical shapedmain body portion 35 containing thesolenoid 31 therein; an extensioncylindrical portion 36 extending rearward from the rear end of themain body portion 36; and a separatingportion 37 separating themain body portion 35 thereof from the extensioncylindrical portion 36. While the extensioncylindrical portion 36 of thehousing 32 is inserted into the inner surface of thevalve body 11 via aseal member 38, and aflange portion 39 formed on the outer circumference surface of themain body portion 35 rests on astep portion 40 formed on the inner surface of thecup portion 11 a of thevalve body 11, thehousing 32 is restrained in its movement against thevalve body 11 by biasing force of areturn spring 41 disposed in theconstant pressure chamber 7 provided on the front side. Aninner flange 5 b is provided on acylindrical portion 5 a of thepower piston 5 provided on the front side (see FIG. 1) and is interposed between theflange portion 39 and thestep portion 40. Thus, thevalve body 11 and thehousing 32 move together in the axial direction. In FIG. 3, reference mark “W” is a wire for supplying electricity to thesolenoid 31. The wire “W” usually extends outside of the brake booster via a connector (not shown) disposed in the front face of the shell 1. - The
hollow guide 17 is disposed inside of themain body 35 of thehousing 32. Thehollow guide 17 comprises alarge end portion 42 engaged with astep portion 35 a of themain body 35 and a smalldiameter axis portion 43 extending from thelarge end portion 42 rearwardly through the separatingportion 37 of the housing 32 (see FIG. 2). Theplunger 18 is slidably inserted into the smalldiameter axis portion 43. Astop key 44 extending the radial direction is inserted into thevalve body 11 through theatmosphere passage 13, and the distal end portion of thestop key 44 is connected to theplunger 18. The proximal end portion of thestop key 44 is arranged to abut against a stopper plate 45 (see FIG. 1) fixed on acylindrical support portion 1 a of the shell 1. The maximum setback position of theplunger 18 is the position where thestop key 44 abuts against thestopper plate 45. Thestop key 44 is also inserted through a opening (long face hole) 21 a. Thevalve seat member 21 is allowed to move relatively to theplunger 18 within the range where thestop key 44 is movable within the opening 21 a. - A
reaction disk 46 and a large diameterproximal end portion 47 a of anoutput rod 47 are disposed on the forward side of thestep portion 35 a of themain body 35 of thehousing 32. The distal end portion of theoutput rod 47 is extended forwardly through the front side of the shell 1 air-tightly. The distal end portion of theoutput rod 47 is connected to and is simultaneously moved with a piston of a master cylinder (not shown). Further, the proximal endlarge diameter portion 47 a of theoutput rod 47 and thereaction disk 46 are restrained from coming out of thehousing 32 by means of aretainer 48 press-fixed on the front end of thevalve body 11 by means of thereturn spring 41. Arecess 42 a is formed in the front face of thelarge end portion 42 of thehollow guide 17. Apressure receiving plate 49 is disposed in therecess 42 a. A depth of therecess 42 a is designed slightly more than the thickness of thepressure receiving plate 49. The front end of theplunger 18 is located slightly forwardly from the bottom of therecess 42 a when the brake booster is in its rest state. A little gap “S” (see FIG. 1) is formed between thepressure receiving plate 49 and thereaction disk 46 in such a state. - There are
pins 50 one ends of which are inserted and fixed into themovable member 34 of thesolenoid mechanism 30 and the other ends of which are inserted into through-holes 51 formed in the separatingportion 37 in thehousing 32. Thevalve seat member 21 having the negativepressure valve seat 22 at its rear end is urged forwardly by means of aspring 52 fixed to theplunger 18 at its one end. The front end of thevalve seat member 21 is normally placed in abutment against the separatingportion 37 in thehousing 32. The through-holes 51 of the separatingportion 37 of thehousing 32 are formed in alignment with the front end of thevalve seat member 21. The other ends of thepins 50 inserted into the through-holes 51 face thevalve seat member 21 with a small gap therebetween. Further, themovable member 34 of thesolenoid mechanism 30 is moved rearwardly by energizing thesolenoid 31, whereby thepins 50 fixed to themovable member 34 move thevalve seat member 21 rearwardly against the urging force from thespring 52 and thevalve spring 25. Consequently, thepoppet valve 26 is separated from theatmospheric valve seat 19 formed at the rear end of theplunger 18. Thus, theatmospheric valve 27 opens independently of the movement of theplunger 18, that is, the movement of theinput rod 16. - A
seal member 53 held on the inner circumference of themovable member 34 provides sealing between themovable member 34 and thehollow guide 17. The outer circumference of themovable member 34 is sealed by the seal member 33 against thehousing 32. Thus, twopressure chambers movable member 34 respectively. Thepressure chamber 54 formed on the front side of themovable member 34 communicates with theconstant pressure chamber 7 provided on the front side through apassage 56 formed in thehousing 32. Thepressure chamber 55 formed on the rear side of themovable member 34 communicates with thevariable pressure chambers passage 57 formed in the separatingportion 37 of thehousing 32. - Now, operation of the brake booster having the above-mentioned construction will be explained.
- The brake booster is installed in a vehicle (not shown) by means of
plural stud bolts 58 provided on the backside face of the shell 1 (see FIG. 3), and a brake pedal (not shown) is connected to theinput rod 16 in this state. Further, a master cylinder (not shown) is attached to the brake booster by means of astud bolt 59 provided on the front side face of the shell 1. Theoutput rod 47 is connected to a piston in the master cylinder in this state. - In the brake booster placed in the initial condition as shown in the Figures (FIGS. 1 through 3), the
constant pressure chambers variable pressure chambers atmospheric valve 27 and thevacuum valve 28 are closed. In this condition, when the brake pedal is depressed to urge theinput rod 16, theplunger 18 moves forward and separates theatmospheric valve seat 19 formed at the rear end thereof from thepoppet valve 26, thereby opening theatmospheric valve 27. As a result, air flows into thevariable pressure chambers atmosphere passage 13, thereby creating a pressure difference between thevariable pressure chambers constant pressure chambers power pistons output rod 47 through thevalve body 11 and starts the braking action. In this initial braking condition, while the gap “S” between thepressure receiving plate 49 and thereaction disk 46 is being closed, so-called “jump-in” occurs, and the booster output force increases irrespective of the input force, thereby generating an adequate initial braking force. - After the jump-in ends, part of the output reaction force from the
output rod 47 is transmitted back to theinput rod 16 through thereaction disk 46, thepressure receiving plate 49 and theplunger 18. When the output reaction force (from the output rod 47) generated by the advancement of thevalve body 11, becomes equal to the brake pedal pressing force, theatmospheric valve 27 is closed, thereby maintaining the booster output force. Further from this condition, when the brake pedal pressing force is increased or decreased to cause imbalance between the reaction force based on the pressure difference and the brake pedal pressing force, either theatmospheric valve 27 or thevacuum valve 28 is opened again, so that the reaction force based on the pressure difference becomes equal to the brake pedal pressing force, thereby adjusting the pressure difference caused between thevariable pressure chambers constant pressure chambers solenoid 31 is not energized, the brake pedal pressing force is multiplied by a predetermined boost ratio, resulting in that the brake booster is operated as a normal brake booster. - In the automatic braking mode in which the
solenoid 31 is energized by the electric current supplied to thesolenoid 31, the electromagnetic force acts on themovable member 34 and shifts themovable member 34 towards the rear side. At that time, thepressure chamber 54 formed at the one end of themovable member 34 becomes equal in pressure to theconstant pressure chamber 7 through thepassage 56, and thepressure chamber 55 formed at the other end of themovable member 34 becomes equal in pressure to thevariable pressure chamber 10 through thepassage 57, gaps formed around thepins 50 in the through-holes 51 and theatmosphere passage 13. If the electric current supplied to thesolenoid 31 increases, the electromagnetic force acting on themovable member 34 exceeds the total spring force of thespring 52 and thevalve spring 25, and themovable member 34 is shifted toward the rear side, whereby thepin 50 fixed thereto moves thevalve seat member 21 towards the rear side. As a result of this, thepoppet valve 26 is separated from theatmospheric valve seat 19 formed at the rear end of theplunger 18 to open theatmospheric valve 27, thereby introducing air into thevariable pressure chambers variable pressure chambers constant pressure chambers power pistons output rod 47 through thevalve body 11, thereby starting the braking action. - When the air is introduced into the
variable pressure chambers pressure chamber 55 provided at the other end of themovable member 34 through thepassage 57 and the gaps around thepins 50 in the through-holes 51. Thereby, a pressure difference force caused by a pressure difference between thepressure chamber 55 and thepressure chamber 54 which is maintained at a negative pressure is created and acts on themovable member 34. This pressure difference force acts as the reaction force in the direction in which themovable member 34 is returned to the front side (i.e., the direction opposite to the direction of the electromagnetic force acting on the movable member 34). As a result, when constant electric current is supplied to thesolenoid 31, that is, when constant electromagnetic force acts on themovable member 34, themovable member 34 is returned to the front side by means of the pressure difference force. At the moment when the electromagnetic force acting on themovable member 34 becomes equal to (i.e., balanced with) the pressure difference force, the shifting movement of themovable member 34 towards the front side stops, thereby closing theatmospheric valve 27, and the booster output force is maintained thereafter. Thus, twopressure chambers movable member 34 constitute a reaction force mechanism that exerts a reaction force on themovable member 34 in proportion to the pressure difference between thevariable pressure chambers constant pressure chambers - Further from this condition, if the electric current supplied to the
solenoid 31 is increased or decreased to cause imbalance again between the electromagnetic force and the pressure difference force, both forces acting on themovable member 34, themovable member 34 is shifted again to balance the pressure difference force and the electromagnetic force, resulting in that either theatmospheric valve 27 or thevacuum valve 28 is opened, thereby adjusting the pressure in thevariable pressure chambers solenoid 31. - In this way, since the booster output force becomes proportional to the electric current supplied to the
solenoid 31, by changing the electric current supplied to thesolenoid 31 across a wide range, the booster output force can be adjusted across a wide range as well. Thus, it is not required to provide a sensor like the master cylinder pressure sensor which was required in the conventional techniques for controlling the booster output force at desired levels. Therefore, the construction of the brake booster can be simplified and the brake booster can be made cheaper. - In the control type brake booster that functions as described above, if air is introduced into the
pressure chamber 55 formed at the other end of themovable member 34 before air is introduced into thevariable pressure chambers movable member 34 i.e. the reaction force acting on themovable member 34, increases before an adequate booster output force is generated. As a result, theatmospheric valve 27 will be prevented from fully opening, causing a delay in introducing an adequate amount of air into thevariable pressure chambers passages 57 formed in the separatingportion 37 of thehousing 32 and the gaps around thepins 50 in the through-holes 51 (see FIG. 4) is made small so that the booster output force will increase at the same rate as the reaction force acting on themovable member 34 increases, or so that an adequate reaction force will be created at the same time or after the booster output force is generated. Thereby, until a sufficient booster output force is generated in response to the electric current supplied to thesolenoid 31, theatmospheric valve 27 is kept open widely, improving the braking response. It is preferable that the total flow area of thepassages 57 and the gaps around thepins 50 in the through-holes 51 is about 0.5-10 square millimeters. - In this way, since the brake booster of this invention is constructed so that the booster output force increases at the same rate as the reaction force acting on the
movable member 34 increases, or so that an adequate reaction force is created at the same time or after the booster output force is generated, thereby improving the braking response in the automatic braking mode and increasing the reliability of the brake booster. - The above embodiment has been described, using a tandem type brake booster. It should however be appreciated that the present invention can also be embodied in a so-called single type brake booster having a single set of variable pressure chamber and constant pressure chamber.
- Further, in the above embodiment, the
passages 57 formed in the separatingportion 37 of thehousing 32 and the gaps around thepins 50 in the through-holes 51 function to introduce air into thepressure chamber 55. It should however be appreciated that only one of thepassages 57 formed in the separatingportion 37 of thehousing 32 or the gaps around thepins 50 in the through-holes 51 may function to introduce air into thepressure chamber 55.
Claims (12)
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2000099478A JP4529105B2 (en) | 2000-03-31 | 2000-03-31 | Brake booster |
JP2000-099478 | 2000-03-31 |
Publications (2)
Publication Number | Publication Date |
---|---|
US20010025565A1 true US20010025565A1 (en) | 2001-10-04 |
US6425312B2 US6425312B2 (en) | 2002-07-30 |
Family
ID=18613825
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US09/814,375 Expired - Lifetime US6425312B2 (en) | 2000-03-31 | 2001-03-21 | Brake booster |
Country Status (3)
Country | Link |
---|---|
US (1) | US6425312B2 (en) |
JP (1) | JP4529105B2 (en) |
DE (1) | DE10113498B4 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE10010385B4 (en) * | 2000-03-03 | 2005-06-16 | Lucas Varity Gmbh | Vacuum brake booster with improved magnetless emergency brake assistance |
JP2001341631A (en) * | 2000-05-31 | 2001-12-11 | Aisin Seiki Co Ltd | Negative pressure type booster |
KR100774131B1 (en) * | 2002-03-20 | 2007-11-08 | 주식회사 만도 | Brake booster for automobile |
JP6426009B2 (en) * | 2015-01-13 | 2018-11-21 | ヴィオニア日信ブレーキシステムジャパン株式会社 | Method of assembling negative pressure booster and output rod |
Family Cites Families (22)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0620789B1 (en) * | 1992-11-13 | 1996-06-26 | ITT Automotive Europe GmbH | Vacuum power brake |
DE4238333C2 (en) * | 1992-11-13 | 2001-10-11 | Continental Teves Ag & Co Ohg | Vacuum brake booster |
DE4422027C2 (en) * | 1994-06-23 | 1998-01-29 | Lucas Ind Plc | Pneumatic brake booster and method for its production |
JPH0853061A (en) * | 1994-08-12 | 1996-02-27 | Jidosha Kiki Co Ltd | Automatic brake device |
US5711202A (en) * | 1995-07-27 | 1998-01-27 | Aisin Seiki Kabushiki Kaisha | Vacuum servo unit for a vehicle braking system |
JPH09164939A (en) * | 1995-12-18 | 1997-06-24 | Aisin Seiki Co Ltd | Negative pressure type assistor |
DE19617277A1 (en) * | 1996-04-30 | 1997-11-06 | Teves Gmbh Alfred | Pneumatic brake force amplifying arrangement for motor vehicle |
DE19735035A1 (en) * | 1997-08-13 | 1999-02-18 | Itt Mfg Enterprises Inc | Pneumatic braking servo for automobiles |
DE19748657A1 (en) * | 1997-11-04 | 1999-05-12 | Lucas Ind Plc | Pneumatic brake booster with mechanical and electromagnetic actuation |
JPH11208453A (en) * | 1997-11-21 | 1999-08-03 | Jidosha Kiki Co Ltd | Brake booster |
JPH11217074A (en) * | 1997-11-28 | 1999-08-10 | Jidosha Kiki Co Ltd | Brake boosting device |
US6155156A (en) * | 1997-11-21 | 2000-12-05 | Jidosha Kiki Co., Ltd. | Brake booster |
JPH11263216A (en) * | 1998-01-16 | 1999-09-28 | Jidosha Kiki Co Ltd | Brake booster |
JPH11217072A (en) * | 1997-11-28 | 1999-08-10 | Jidosha Kiki Co Ltd | Brake boosting device |
JP2000079877A (en) * | 1998-06-29 | 2000-03-21 | Aisin Seiki Co Ltd | Negative pressure-type booster |
JP2000103330A (en) * | 1998-07-31 | 2000-04-11 | Aisin Seiki Co Ltd | Negative pressure booster |
US6332391B1 (en) * | 1998-08-07 | 2001-12-25 | Jidosha Kiki Co., Ltd. | Automatic brake booster |
JP2000108880A (en) * | 1998-09-30 | 2000-04-18 | Aisin Seiki Co Ltd | Negative pressure type booster |
JP3777833B2 (en) * | 1998-11-04 | 2006-05-24 | ボッシュ株式会社 | Brake booster |
JP4478847B2 (en) * | 1999-04-30 | 2010-06-09 | 日立オートモティブシステムズ株式会社 | Booster |
DE10020805A1 (en) * | 1999-04-30 | 2000-11-16 | Tokico Ltd | Brake booster has electromagnetic biasing device arranged so variable pressure and constant pressure in divided housing chambers act on opposite ends of movable element |
JP2001071889A (en) * | 1999-09-03 | 2001-03-21 | Bosch Braking Systems Co Ltd | Automatic servo brake device |
-
2000
- 2000-03-31 JP JP2000099478A patent/JP4529105B2/en not_active Expired - Lifetime
-
2001
- 2001-03-20 DE DE10113498A patent/DE10113498B4/en not_active Expired - Lifetime
- 2001-03-21 US US09/814,375 patent/US6425312B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JP4529105B2 (en) | 2010-08-25 |
DE10113498A1 (en) | 2001-10-11 |
JP2001278035A (en) | 2001-10-10 |
DE10113498B4 (en) | 2007-11-15 |
US6425312B2 (en) | 2002-07-30 |
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